Review ArticleFood Waste to Energy An Overview of Sustainable Approachesfor Food Waste Management and Nutrient Recycling

Kunwar Paritosh1 Sandeep K Kushwaha2 Monika Yadav1 Nidhi Pareek3

Aakash Chawade2 and Vivekanand Vivekanand1

1Centre for Energy and Environment Malaviya National Institute of Technology Jaipur Rajasthan 302017 India2Department of Plant Breeding Swedish University of Agricultural Sciences PO Box 101 230 53 Alnarp Sweden3Department of Microbiology School of Life Sciences Central University of Rajasthan Bandarsindri KishangarhAjmer Rajasthan 305801 India

Correspondence should be addressed to Vivekanand Vivekanand vivekanandceemnitacin

Received 14 November 2016 Revised 29 December 2016 Accepted 12 January 2017 Published 14 February 2017

Academic Editor Jose L Campos

Copyright copy 2017 Kunwar Paritosh et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Food wastage and its accumulation are becoming a critical problem around the globe due to continuous increase of the worldpopulation The exponential growth in food waste is imposing serious threats to our society like environmental pollution healthrisk and scarcity of dumping land There is an urgent need to take appropriate measures to reduce food waste burden by adoptingstandardmanagement practices Currently various kinds of approaches are investigated in waste food processing andmanagementfor societal benefits and applications Anaerobic digestion approach has appeared as one of the most ecofriendly and promisingsolutions for food wastes management energy and nutrient production which can contribute to worldrsquos ever-increasing energyrequirements Here we have briefly described and explored the different aspects of anaerobic biodegrading approaches for foodwaste effects of cosubstrates effect of environmental factors contribution of microbial population and available computationalresources for food waste management researches

1 Introduction

Food Waste Food waste (FW) (both precooked and leftover)is a biodegradable waste discharged from various sourcesincluding food processing industries households and hos-pitality sector According to FAO nearly 13 billion tonnesof food including fresh vegetables fruits meat bakery anddairy products are lost along the food supply chain [1] Theamount of FW has been projected to increase in the next 25years due to economic and population growth mainly in theAsian countries It has been reported that the annual amountof urban FW in Asian countries could rise from 278 to 416million tonnes from 2005 to 2025 [2] Approximately 14billion hectares of fertile land (28 of the worldrsquos agriculturalarea) is used annually to produce food that is lost or wastedApart from food and land resource wastage the carbonfootprint of foodwaste is estimated to contribute to the green-house gas (GHG) emissions by accumulating approximately

33 billion tonnes of CO2 into the atmosphere per yearConventionally this food waste which is a component ofmunicipal solid waste is incinerated [3ndash7] or dumped inopen area which may cause severe health and environmentalissues Incineration of food waste consisting high moisturecontent results in the release of dioxins [8] whichmay furtherlead to several environmental problems Also incinerationreduces the economic value of the substrate as it hinders therecovery of nutrients and valuable chemical compounds fromthe incinerated substrateTherefore appropriate methods arerequired for the management of food waste [9] Anaerobicdigestion can be an alluring option to strengthen worldrsquosenergy security by employing food waste to generate biogaswhile addressing waste management and nutrient recyclingThe quantity of wasted food around the globe and itsbioenergy potential via anaerobic digestion were reportedearlier [10 11] and are summarized in this work (Figures 1 and2)

HindawiBioMed Research InternationalVolume 2017 Article ID 2370927 19 pageshttpsdoiorg10115520172370927

2 BioMed Research International

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Figure 1 (a) Worldwide generation of food waste in developed and developing countries (b) Worldwide bioenergy potential from FW indeveloped and developing countries (c) Per capita food waste generation in developed and developing countries

BioMed Research International 3

Cer

eals

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uits

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ilkBa

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Total food waste (world)

020000400006000080000

100000120000

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es

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eals

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ts

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crop

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Milk

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onut

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Total food waste (Asia)

010000200003000040000500006000070000

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Ton

nes

(b)

Figure 2 Typical wasted foods in world and in Asia

Food waste mainly consists of carbohydrates proteinslipids and traces of inorganic compounds The compositionvaries in accordance with the type of food waste and itsconstituents Food waste consisting of rice and vegetablesis abundant in carbohydrates while food waste consistingof meat and eggs has high quantity of proteins and lipidsTable 1 summarizes the composition of food waste studied indifferent parts of the globe

2 Anaerobic Digestion

Generation of methane via anaerobic process is an appro-priate solution for food waste management The process haslesser cost and low residual waste production and utilizationof food waste as renewable source of energy [12 13] Table 2summarizes the studies pertaining to anaerobic digestion ofvarious kinds of FWs

Anaerobic digestion consists broadly of three phasesnamely enzymatic hydrolysis acid formation and gas pro-duction Figure 3 depicts the digestion process

21 Enzymatic Hydrolysis In the first phase large polymermolecules that cannot be transported to cell membranes bymicroorganisms are broken down by hydrolases secreted byfacultative or obligate anaerobic hydrolytic bacteria Hydrol-ysis breaks down the polymers into oligomer or monomericunits Polysaccharides are broken down into oligosaccharidesandmonosaccharides for example (1) represents productionof glucosemolecules by starch hydrolysis Proteins are brokendown into peptides and amino acids and lipids are convertedinto glycerol and fatty acid

119899C6H10O5 + 119899H2O 997888rarr 119899C6H12O6 (1)Mittal [42] reported that in the anaerobic conditions thehydrolysis rate is relatively slower than the rate of acidformation and depends on the nature of substrate bacterialconcentration pH and the temperature of the bioreactorOther parameters such as size of the substrate particles pHproduction of enzymes and adsorption of enzymes on thesubstrate particles also affect the hydrolysis rate Bryant [43]reported that Streptococcus and Enterobacter are genera ofanaerobes that are responsible for hydrolysis

22 Acidogenesis Phase In the second phase acidogenesistakes place in which hydrolytic products are fermented tovolatile fatty acids such as acetate propionate butyrate valer-ate and isobutyrate alongwith carbon dioxide hydrogen andammoniaDuring acidification facultative anaerobic bacteriautilize oxygen and carbon creating an anaerobic conditionfor methanogenesis The monomers obtained in phase onebecome substrates for the microbes in phase two where thesubstrates are converted into organic acids by a group ofbacteria

Acetate hydrogen and carbon dioxide can be uti-lized directly for methane production However propionatebutyrate valerate and isobutyrate are introduced for furtherdegradation by syntrophic acetogenic bacteria to form acetateand hydrogen [42ndash44]

23 Acetogenesis Acetogenic bacteria belonging to generaSyntrophomonas and Syntrophobacter [44] convert the acidphase products into acetates (2) and hydrogen Few acetatemolecules are also generated by reduction of carbon diox-ide using hydrogen as an electron source Acetates willfurther be utilized by methanogens in subsequent stepsHowever hydrogen released in the process exerts inhibitoryeffect on microorganisms Therefore in anaerobic digestersacetogenic bacteria live in syntrophic relationship withhydrogenotrophic methanogens that remove the hydrogenby utilizing it for methane formation Also acetogenesisis the phase which depicts the efficiency of the biogasproduction because 70 of methane arises when acetatereduces Simultaneously 11 hydrogen is also formed duringthe process [44]

119899C6H12O6 997888rarr 3119899CH3COOH (2)

24 Methanogenesis In the last phase methanogenesis takesplace which is carried out by methanogens belonging toArchaea Methane can be produced either by fermentationof acetic acid or by reducing carbon dioxide Therefore theproducts of previous phase that is acetic acid hydrogen andcarbon dioxide act as a precursor for methane formationOnly 30 of methane produced in this process comes from

4 BioMed Research International

Table 1 Composition of FW reported in various literatures

Moisture Total solid Volatile solid Total sugar Starch Cellulose Lipids Protein Ash References759 241 NR 423 293 NR NR 39 13 [14]803 197 954 598 NR 16 157 218 19 [15]828 172 891 627 461 23 181 156 NR [16]752 248 NR 502 461 NR 181 156 23 [16]857 143 982 423 283 NR NR 178 NR [17]828 172 850 627 461 23 181 156 NR [18]613 387 NR 690 NR NR 64 44 12 [19]817 183 875 355 NR NR 241 144 NR [20]815 185 941 550 240 169 140 169 59 [21]819 143 982 483 423 NR NR 178 NR [22]

Table 2 Anaerobic digestion processes of food waste for methane production

Waste Inoculum Vessel type Duration (d) HRT (d) CH4 yield(mlgVS) CH4 References

FW Cow manure Bioreactor with 5 L workingvolume 29 1 530 70 [23]

FW Anaerobic SS Pilot scale 5 tonsd 90 NR 440 70 [24]

FW Anaerobic SS Bioreactor with 12 L workingvolume 60 20 NR 688 [25]

FW SS Bioreactor with 45 L workingvolume 200 1ndash27 520 90 [26]

FW NR 900m3 tank volume 426 80 399 62 [27]FW Anaerobic SS CSTR with 3 L working volume 225 16 455 NR [28]

FW NR Digester with 800ml workingvolume 30 Batch 410 66 [29]

FW Anaerobic SS Batch 28 10ndash28 440 73 [30]FW SS CSTR with 10 L working volume 150 5 464 80 [31]

FW Landfill soil and cowmanure Batch 5 L 60 20ndash60 220 NR [32]

Substrate(i) Carbohydrates(ii) Protein(iii) Fats

Soluble organic

compounds

(i) Sugar(ii) Amino acids(iii) Fatty acids

Acidformation

(i) Alcohols(ii) Carbonic Acid(iii) Volatile fatty acids

Acetic acid formation

Biogas

Hydrolysis

Acetogenesis

Acidogenesis

Methanogenesis

(i) CH4(ii) CO2

(i) CH3COOH(ii) NH3 H2 CO2 NH4 H2S

Figure 3 Anaerobic digestion phases

BioMed Research International 5

Table 3 Microorganism cooperation in organic matter degradation [33 34]

Reaction Type Microorganism Active Genera Product

Fermentation Hydrolytic bacteriaBacteroides Lactobacillus

Propionibacterium SphingomonasSporobacterium Megasphaera

Bifidobacterium

Simple sugars peptidesfatty acids

Acidogenesis Syntropic bacteria Ruminococcus Paenibacillus Clostridium Volatile fatty acids

Acetogenesis Acetogenic bacteria Desulfovibrio AminobacteriumAcidaminococcus CH3COOH

Methanogenesis Methanogens (Archaea)

Methanosaeta MethanolobusMethanococcoides MethanohalophilusMethanosalsus MethanohalobiumHalomethanococcus MethanolaciniaMethanogenium Methanoculleus

CH4

carbon dioxide reduction carried out by methanogens [4546]

CH3COOH 997888rarr CH4 + CO2 (3)

Methane can be generated in two ways by two typesof methanogens (a) acetoclastic methanogens that pro-duce methane from acetic acid and (b) hydrogenotrophicmethanogens that utilize hydrogen to reduce carbon dioxide

CO2 + 4H2 997888rarr CH4 + 3H2O (4)

Table 3 summarizes genera active in anaerobic digestion andthe microorganism cooperation in organic matter degrada-tion

3 Food Waste as a Substrate

Degradability of foodwaste used as substratemainly dependsupon its chemical composition It is quite challenging toknow the exact percentage of different components of thecomplex substrate because of its heterogeneous nature Var-ious researchers have investigated the potential of foodwaste as a substrate for biomethanation Viturtia et al [47]inspected two stages of anaerobic digestion of fruit andvegetable wastes and achieved 951 volatile solids (VS)conversion with a methane yield of 530mLgVS In a studyperformed by Lee et al [23] FWwas converted into methaneusing a 5-L continuous digester resulting in 70 VS conver-sion with a methane yield of 440mLgVS Gunaseelan [24]used around 54 different types of food and reported methaneyield ranged from 180 to 732mLgVS depending on the ori-gin of wastes Cho et al [48] reported 472mlgVS methaneyield with 86 anaerobic biodegradability of the Korean foodwaste Yong et al [49] have reported 0392m3 CH4kg-VSwhen canteen food wastemixed with straw in the ratio of 5 1Food waste as a substrate has potential to provide high biogasyield in comparison to cow manure whey pig manure cornsilage and so forth [50]

4 Key Parameters Affecting Biomethanation

For anaerobes to work with high metabolic activity it isimperative to have controlled environmental conditions Themethanogenic bacteria are very sensitive towards unfavorablesurvival conditions Therefore it is vital to maintain optimalcondition to flourish the process of methanation Biometha-nation process primarily depends upon seeding temperaturepH carbon-nitrogen (CN) ratio volatile fatty acids (VFAs)organic loading rate (OLR) alkalinity total volatile solids(VS) and hydraulic retention time (HRT) and nutrientsconcentration It was also reported that the concentrationsof water soluble material such as sugar amino acids proteinandminerals decrease andwater nonsolublematerials such aslignin cellulose and hemicellulose increase in content [51]

41 Seeding Seeding may speed up the stabilization of thedigestion process The most commonly used materials forinoculation are digested sludge from sewage plant landfillsoil and cow dung slurry

It was reported that the use of goat rumen fluid [52] asinoculum at the rate of 8 (vv) is very efficient for biogasproduction

42 Temperature Methanogenesis has been reported from2∘C in marine sediments to over 100∘C in geothermal areas[53] Methanogens thrive best at around 35∘C (mesophilic)and 55∘C (thermophilic) respectively Environmental tem-perature is also a huge concern for anaerobic microbialculture as change of acetic acid to methane depends mostlyupon temperature It has been reported that the optimumrange of temperature is 35ndash40∘C for mesophilic activity and50ndash65∘C for thermophilic activity [54 55] Bouallagui et al[56] have reported that at 4 total solid methane contentwas found to be 58 65 and 62 at temperatures 20∘C35∘C and 55∘C respectively At 8 total solid methanecontent was found to be 57 and 59 at 35∘C and 55∘Crespectively In a study reported by Kim et al [57] methanecontent was found to be 656 662 674 and 589at temperatures 40∘C 45∘C 50∘C and 55∘C respectively Inanother experiment performed by Gou et al [58] codigestion

6 BioMed Research International

Table 4 CN ratio for some materials

Material N C NAnimal urine 15ndash20 1Cotton stalks 17 30Cow buffalo manure 14ndash3 15ndash40Oat straw flax straw 1ndash12 50ndash60Wheat and rice straw 03ndash05 120ndash150Sawdust 01ndash025 200ndash500

of waste activated sludge with food waste was reported tohave highest gas production rate at 55∘C which was 16 and13 times higher than the gas production at 35∘C and 45∘C

43 pH The pH of bioreactor affects the microbial activityin anaerobic digestion and its efficiency Wang et al [59]reported that optimum pH range is 63ndash78 Initially due toexcess of carbon dioxide pH drops to 62 and after 10 daysit starts rising and stabilizes between 7 and 8 Also Lee etal [60] indicated that optimum range of methanogenesisusing food waste leachate was 65ndash82 The main reasonsfor pH variation are VFAs bicarbonate concentration andalkalinity of the system Goel et al [61] used NaOH andNaHCO3 for controlling pH in anaerobic digestion used forbiomethanation from food waste

44 CarbonNitrogen Ratio Mittal [62] has reported thatdigestion of substrate will proceed more rapidly if the CNratio would be 25ndash30 1 This leads to a conclusion thatbacterial community use up carbon 25ndash30 times faster thannitrogen If the ratio is not adequate the nitrogen wouldget exhausted while there would be some carbon left whichwill cause bacteria to die Excess of nitrogen would lead toammonia formation which will inhibit the digestion processCodigesting dairy manure chicken manure and wheat strawyielded maximum methane when CN ratio was 272 withstable pH [59] In another study performed by Zeshan et al[63] anaerobic digestion performed well at CN ratio of 27An optimum amount of carbon content was having positiveeffect on avoiding excessive ammonia inhibition [64ndash66]Table 4 [67] summarizes the CN ratio of a few selected feedstock

45 Volatile Fatty Acids (VFAs) It has been reported that theproduction and accumulation of volatile fatty acid (VFAs)could show inhibitory and detrimental effects on anaerobicdigestion process which could lead to slow production of bio-gas [68ndash70] VFAs inhibition on the activity of methanogensis caused by a pH drop which may lead to the activity loss ofacid-sensitive enzymes [71] Also high levels of undissociatedacids which can penetrate cell membranes may damagemacromolecules [72]The concentration of VFA in anaerobicdigestion for the solid state of food wastes could rise up to20 gL which is much higher than that in a wastewater anaer-obic process [73] In the optimum conditions required formetabolic activity VFAs range in between 2000ndash3000mgL[74]

46 Organic Loading Rate (OLR) Organic loading rate sim-ply refers to quantity of feed processed per unit volume ofreactor per day Taiganides [75] had reported that controlleddigestion is attained when the loading rate is between 05 kgand 2 kg of total VSm3d In an experiment conducted byNagao et al [76] the volumetric biogas production rateincreased to approximately 27 42 58 and 66 LLd as OLRincreased to 37 55 74 and 92 kg-VS m3d respectively andwas maintained at the same At the highest OLR (129 kg-VSm3d) the volumetric gas production rate decreased belowthe gas production rate at OLR of 74 kg-VS m3d In a studyperformed for comparing autoclaved and untreated foodwaste [77] highest methane yield was obtained at organicloading rate of 3 kgVSm3d for untreated food waste andat 4 kgVSm3d for autoclaved food waste The study wasconducted at 2 3 4 and 6 kgVSm3d Agyeman and Tao[78] digested food waste with dairy manure anaerobicallyat different organic loading rates and reported that bio-gas production rate increased by 101ndash116 when OLR wasincreased from 1 to 2 gVSLd and only by 25ndash38 whenOLR was further increased from 2 to 3 gVSLd Specificmethane yield peaked at the OLR of 2 gVSLd in thedigesters with fine andmedium food waste Also codigestionof food waste with activated sludge was performed in bothmesophilic and thermophilic anaerobic systems at differentOLR The thermophilic system exhibited the best load bear-ing capacity at extremely high OLR of 7 gVSLd while themesophilic system showed the best process stability at lowOLRs (lt5 gVSLd) [79]

For a given size of biogas plant there would be anoptimum loading rate beyond which further loading will notbe fruitful as it may lead to accumulation of excess VFAs andresults in a collapsed reactor [80]

47 Ammonia Biodegradation of protein or other nitrogen-rich substrate produces ammonia and exists in the formof ammonium ion (NH4

+) and NH3 [81 82] It could bebeneficial for the growth of microbes or sometime havedetrimental effect on them [82 83] Ammonia plays a vitalrole in CN ratio and could affect the performance ofdigestion process [59] The reaction between ammonia andVFAs have been reported by Zhang et al [84] and are asfollows

C119909H119910COOH 999445999468 C119909H119910COOminus +H+ (5)

NH3 sdotH2O 999445999468 NH4++OHminus (6)

C119909H119910COOH +NH3 timesH2O

997888rarr C119909H119910COOminus + NH4++H2O

(7)

where C119909H119910COOH represents VFAs

48 Nutrient Microbes use carbon to fulfil energy require-ment and nitrogen for building cell wall structure In addi-tion microbes also need small quantity of micro nutrient[85] such as calcium sodium potassium magnesium andchlorine Also for enzyme synthesis and for maintaining

BioMed Research International 7

enzyme activity heavy metal ions such as Cr Co CuZn and Ni are required in biomethanation [86ndash88] Effectof concentration of sodium potassium and calcium wasobserved during anaerobic digestion activity No inhibitionwas observed when concentration of calcium was increasedup to 7000mgL [89] however optimum concentration wasreported 150ndash300mgL [90] Concentration of heavy metalscould have inhibitory effects on methanogenic activity andinhibition degrees depend upon many factors such as thetotal metal concentration chemical forms of the metals pHand redox potential [91 92]

5 Biochemical Methane Potential (BMP)

Biochemical methane potential is an important assay forelucidation of anaerobic digestion There is an increasedadaptation of BMP assay in recent studies

In an experiment performed for mixed food waste likeboiled rice cabbage and cooked meat which were digestedwith cellulase as control has manifested greater rate ofproduction of methane which is about 472mlgVS with totalreduction in VS up to 86 [48]

In another study performed on canteen waste mixed withstraw in different ratios BMP for food waste and straw was026 and 016m3 CH4kg-VS respectively which shows thatfood waste is easily biodegradable waste while the strawwas difficult to degrade anaerobically which may be due topresence of lignin [49]

Digesting food and vegetables anaerobically yieldedmethanewith aminimumamount of 03 LgVS in every sam-ple which also incorporate as commercial value for anaerobicdigestion [93] In an experiment conducted by Elbeshbishyet al [94] preincubated seed sludge has been used alongwith running seed sludge for BMP test of food waste alongwith primary sludge The maximum methane productionrates using nonincubated inoculum were higher (114mLCH4minusg TCODsub) than those using preincubated inoculum

at all substrate-to-inoculum ratios Lisboa and Lansing [95]codigested four food waste substrates (meatball chickencranberry and ice cream processing wastes) for 69 dayswith flushed dairy manure and have reported an increase inmethane production Their findings suggested that additionof even small quantity of food waste to dairy manure hassignificantly enhanced the BMP levels It was observed thatthe extent of increase in BMP following the addition of foodwaste had wide range starting from 67 to 2940 for ice creamand chicken processing waste respectively

Biogas potential of the dry fraction from pretreatment offood waste from households has been evaluated by Murtoet al [96] A higher methane yield (152 plusmn 22m3ton) wasobtained from digestion of the dry fraction alone Dryfractionmixedwith structuralmaterial produced lower levelsof biogas (112 plusmn 21m3ton) compared to digestion of dryfraction alone

Autoclaved and untreated food waste BMP assay wasperformed byTampio et al [77] Foodwastewas autoclaved at1600∘C 62 bar It has been reported that methane yield at allthe loading rates (2 3 4 and 6 kg-VSm3d) was 5ndash10higherfor untreated food waste which was 0483m3 CH4kgVS as

compared to 0439m3 CH4kgVS obtained from autoclavedfood waste

6 Pretreatment Methods for Food Waste

Anaerobic digestion is now widely embraced to managesolid waste and energy recovery However the recalcitranceimposed by the compositional and structural features offood waste that is degree of polymerisation crystallinitylignin and pectin content accessible surface area and soforth results in limiting the hydrolysis step of anaerobicdigestion such as foodwaste containing uncooked vegetablesthat consist of raw starch that has high degree of crys-tallinity which hinders its hydrolytic degradation Thereforea pretreatment step prior to anaerobic digestion is requiredto increase the degradability of food waste by increasingthe surface area and reducing the degree of polymerisationand crystallinity Pretreatment technologies like mechanicalthermal chemical and biological ones may be applied priorto anaerobic digestion to reduce the crystallinity and enhancethe production of methane using wasted food Researchis earlier carried out to investigate the effect of differentpretreatment methods on anaerobic digestion of food wasteMicrowave pretreatment of food waste with intensity of78∘Cmin resulted in enhanced biogas production and about6 and 24higher COD solubilisation [97] In another studydone by Izumi et al [98] 28 higher biogas production wasobtained using food waste when it is treated with beads millMa et al [99] has used different pretreatment techniques tokitchen waste By addingHCL until the pH reduced to 2 48highermethane productionwas reportedMeanwhile heatingthe same food waste at 120∘C at 1 bar for 30 minutes gave 24higher gas production Again freezing the same food wasteat minus80∘C for 6 h and thawing for 30min result in 56 highergas production Applying pressure of 10 bar followed then bydepressurization produces 48 more biogas

Sometimes intensity of temperature plays a vital role inthermal pretreatment Wang et al [100] have reported thatpretreating food waste at 70∘C for 2 hours results in only269 higher methane production while treating it for 1 hourat 150∘C results in 119 higher gas production Numberof days of pretreatment could result in different rate of gasproduction In an experiment conducted by Stabnikova et al[101] total production of biogas increased up to 237 whenfreozen and thawed for 7 days On the contrary only mereincrease was recorded when it was frozen and thawed for 12days that is 85 In a study when food waste and fruit andvegetable waste heated at 175∘C for 60min this showed 79and 119 decrease in biogas production respectively [102]Food waste (sorted frommunicipal solid waste) when treatedwith electroporation (400 pulses) [79] yielded 20ndash40higherbiogas production due to substrate cell breakage Semiaerobicand anaerobic prehydrolysis of food waste resulted in 95COD destruction with 500mlgVS methane yield [103]Microaeration pretreatment [104] to the codigestion of brownwater and food waste for 4 days with 375ml O2Ld hasshown 21 higher methane yield for inoculated substratewhereas only 10 higher methane yield was observed forsubstrate without the inoculum

8 BioMed Research International

7 Codigestion of Food Waste

Due to high potential for biomethanation food waste isa reliable and promising substrate for anaerobic digestionactivity However longer duration of digestion may some-times lead to inhibition because of improper nutrient balance[105] On the other hand concentration of lipid in foodwaste is always higher than the limited concentration [84106] To restrain this inhibition many strategies have beenadopted by researchers to codigest the food waste with cattlemanure green waste or waste water sludge or with dairywaste Table 5 summarizes the codigestion of FW with otherorganic substrates for improving performance of anaerobicprocess

8 Anaerobic Reactors

To carry out biomethanation in practical manner differenttypes of reactors are required The researchers have useddifferent types of anaerobic reactors such as single stage andtwo-stage reactors semidry reactors solid state anaerobicreactors upflow anaerobic solid state reactors and hybridreactors for the execution of biomethanation process

Configuration of process is quite important for efficiencyofmethane production process For this single stage and two-stage process have been employed for biodegradable wastetreatment Forster-Carneiro et al [30] have reported thatwhen all phases of anaerobic digestion namely hydrolysisacidogenesis acetogenesis and methanogenesis take placesimultaneously in single reactor system encounters fewertechnical failures When all polymeric compounds such ascarbohydrates protein and fat are converted into CH4 H2SNH3 and CO2 in a single vessel then that is termed as singlestage reactor Also stability of single stage anaerobic digesterfor easily degradable FW is a matter of deep concern [23]

Chu et al [107] reported that two-stage anaerobic digesterhas been used to produce both hydrogen and methanein two separate reactors from food waste In this type ofsystem in the first stage acidogens and hydrogen producingmicroorganisms which are having faster growth rate areenriched for hydrogen production and volatile fatty acid Inthe second stage acetogens and methanogens are built upwhere volatile fatty acids are converted into methane andcarbon dioxide

It has been reported that two-stage anaerobic digestionis providing more efficient operation as compared to singlestage Park and Li [65] have reported that highest methanerecovery from kitchen waste when operated in both singlestage and two-stage system was obtained as 90 (based onCOD) which was determined at the OLR of 15 g CODLdIt was also reported by Massanet-Nicolau et al [108] thatmethane yield from food waste increased by 37 in two-stage methane fermentation process The highest methaneyields from FWs were reported by Koike et al [109] Biogasproduction of 850 LgVS during the two-stage hydrogen andmethane production processing of FWwas obtained by them

On the other hand solid state anaerobic digestion hasseveral advantages over liquid anaerobic digestion in terms ofsmaller volume required for reactors low material handling

lowwater requirement and so forth It has been reported thatfood waste is generally treated by liquid anaerobic digestionand organic fraction of municipal solid waste as well aslignocellulosic biomass can be treated by solid state anaerobicdigestion [76]

Hybrid reactors also have been proposed by someresearchers In a study performed by Hai-Lou et al [110]food waste was digested at 35∘C for 16 days in a hybridreactorThe result showed treatment efficiencies of 77ndash80 oftotal organic content removal 59-60 volatile solid removaland 79-80 total COD reduction were achieved Also highmethane content (68ndash70) from the methanogenic phasefavors the application of hybrid anaerobic solid liquid biore-actor to practical solid waste management

9 Mathematical Modelling ofAnaerobic Digestion

Based on the total operating solid content anaerobic diges-tion can be categorized as liquid state anaerobic digestion (L-AD) (TS le 15) or solid state anaerobic digestion (SS-AD)(TSge 15) [111] L-AD is adopted to treat liquid organic wastesuch as sewage sludge animal manure and waste water fromfood processing unit while SS-AD is adopted to treat solidorganic material such as yard trimmings crop residues andorganic fraction of municipal solid waste and food waste [112113] As compared to L-AD SS-AD is having advantages ofsolid loading capacity more volumetric biogas productivityand less need of energy [114]

Besides having economic and environmental benefits andbeing a promising technology a major disadvantage of solidstate anaerobic digestion is the low rate of reaction [115 116]Slow release of soluble substrate for microbial metabolismcould be the possible reason for this Till date SS-AD systemsare operated empirically and still lacking inmechanistic toolsfor controlling the process [117] Application of mathematicalmodel can be applied to anaerobic digestion for mechanismexplanation and its engineering process and parametersaffecting biomethanation and their interaction with eachother [34 118] Many researchers have adopted mathemat-ical modelling for optimizing anaerobic digestion activitybased on theoretical empirical and statistical approach Ina theoretical approach six models were adopted namelytwo-particle model [119] reaction front [120 121] distributedmodel [122ndash126] spatial temporalmodel [127 128] modifiedADM 1 [129ndash131] and diffusion limitation [132] Empiricalapproach leads to logistic modelling [133] and general kineticmodelling [134 135] Also statistical approaches such aslinear regression and artificial neural network have beenadopted [136ndash140]

Statistically derived models may emphasize prediction ofsystem behaviour and are especially useful when there are alimited number of targeting outputs while the models areblack boxmodels andmight not provide enough informationto unveil system mechanisms

On the other hand theoretical models provide moreinsight into the complex system mechanisms while simpli-fication is required to find general applications [34 141]

BioMed Research International 9

Table 5 Codigestion of food waste with other organic substrates

Feedstock Action of codigestion Influencing factor Ref

FW + CM Improve methane yield and systemstability

High buffering capacity and traceelements supplement [29]

FW + livestock waste Improve methane yield and VS reduction Higher buffering capacity [35]FW + yard waste Improve methane yield Less VFA accumulation [36]FW + dewatered sludge Enhance system stability Less inhibition from Na+ [28]FW + sewage sludge Afford high organic loading rate High buffering capacity from ammonia [37]FW + green waste Improve VS reduction CN ratio [38]FW + brown water Improve methane yield High buffering capacity [39]

FW + press water Improved system stability and methaneyield High buffering capacity [40]

FW + distillerrsquos grain Improved biogas production High buffering capacity from ammonia [41]

10 Microbial Community Analysis

Anaerobic digestion is the outcome of complex microbiomeworking in solidarity A guild of microorganisms work ondifferent phases of anaerobic digestion (Figure 4) maintain-ing a synergistic balance to ensure the stability of anaerobicdigestion However anaerobic digesters often suffer withvarious instabilities pertaining to inhibition foaming andacidification especially at high organic load rates (OLRs)[142] These instabilities are generally associated with thecharacteristics and dynamics of the microbial communitiesinvolved in anaerobic digestion process Therefore micro-bial community analysis investigating the composition andbehaviour of microbial communities can be helpful tooptimize stable and efficient process operation The high-throughput sequencing technologies have further opened upnew avenues for investigations of microbial communitiesduring anaerobic digestion Methods for revealing microbialcommunity compositions are based on the generation of16S rRNA gene clone libraries and 16S rRNA ampliconsArchaeal community are identified by targeting mcrA geneThe sequence reads are then analyzed by sophisticated bioin-formatics tools for taxonomic distribution and functionalannotations

Lim and Wang [104] studied microbial community forsingle phase and two-phase anaerobic digestion of food wasteand found predominance of Firmicutes and greater bacterialdiversity in two-phase continuous stirred tank reactor that ledto 23 higher methane yield in comparison to single phaseanaerobic digestion Methanosaeta dominated the archaealcommunity of both single phase and two-phase reactors[143] Cho et al [144] investigated methanogenic communityduring dry anaerobic digestion of food waste and observeda significant reduction in methanogen diversity after accli-mation to dry AD Almost all sequences obtained from dryanaerobic digester sludge belonged toMethanosarcina genusreported to be more tolerant to sudden change in pH anduse both acetoclastic and hydrogenotrophic pathways whichmake them more suitable for surviving in comparison toMethanosaeta Gou et al [58] investigated effect of temper-ature and organic loading rate on microbial community offood waste anaerobic digestion and found significant effect of

temperature on the richness of microbial community whichwas more diverse at 35∘C in comparison to 45∘ and 55∘CAt 55∘C only 5 species remain abundant that explains thatthermophilic bacteria aremore sensitive towards temperaturevariation

Wan et al [145] classified the nucleotide sequences byusing the ribosomal database project classifier software andshowed that Proteobacteria Firmicutes and Bacteroideteswere the most abundant microorganisms during the entireprocess of anaerobic digestion The diversity of microorgan-isms significantly increased during active methanogenesis incomparison to day 0 with addition of Synergistetes Tener-icutes Spirochaetes and Actinobacteria Li et al [142 146]introduced disturbance in OLR into mesophilic anaerobicdigester and carried out microbial community analysis dur-ing stable and deteriorative phases by employing pyrose-quencing Microbial communities were investigated using454 pyrosequencing Raw sequences were quality checked bymothur software and aligned with SILVA alignment In hisstudy the acidogenic bacteria and syntrophic VFA oxidizerswere found abundantly in deteriorative phase suggesting thatduring high OLR hydrolysis and acidogenesis surpassedthe rate of methanogenesis which led to the irreversibleacidification of accumulated VFAs

Zamanzadeh et al [147] investigated the effect of diges-tate recirculation on microbial community by using Illu-mina sequencing Taxonomic assignment of sequences wasdone by using QIIMErsquos uclust-based taxonomy assignerProteobacteria Firmicutes Chloroflexi and Bacteroideteswere found to be the dominant bacterial phyla in bothdigester configuration types (with and without recircula-tion) Methanosaeta and Methanobacterium were dominantgenera among archaeal population accounting for 65 and32 of Euryarchaeotarsquos reads in mesophilic digester withoutrecirculation while in digester with digestate recirculationMethanosaeta accounted for 91 of all EuryarchaeotarsquosTheseresults show the prevalence of acetoclastic methanogens overhydrogenotrophic methanogens which acknowledge acetatereduction as the main pathway of methane formation Simi-larly Gulhane et al [148] studied the microbial communityunder effect of no digestate recirculation 25 digestaterecirculation and 100 digestate recirculation Illumina

10 BioMed Research International

Hydro producing

Homo acetogenic

Hydrolytic bacteria (I)

Methanogenic bacteria (IV)

Acetic acid

Complex organic compound

Organic acidneutral compound

bacteria (III)

CH4CO2

one-carbon compound

H2CO2

acetogenic bacteria (II)

Figure 4 Significance of the microbial population in anaerobic digester

sequenced reads were pair assembled using PANDAseq andmothur software was used to align and filter and trim andremove chimeras and classify and assign taxonomyThe resultrevealed the domination of hydrolytic and fermentative phylain digester with no digestate recirculation while syntrophicacetogenic bacteria dominated the digester with recircula-tion

Guo et al [149] carried out comparative analysis ofthe microbial community response to increasing OLR inmesophilic and thermophilic reactor and reported thatmesophilic reactor had greater richness of microorganismsin comparison to thermophilic reactor They also reportedthe dominance of Methanosaeta in archaeal community inmesophilic reactor while presence of MethanothermobacterandMethanoculleus were favored in thermophilic reactor

11 Metagenomic Tool and Techniques forAdvance Practices

In a fast-growing world food wastage and its managementare one of the major challenges faced by our society due toinherited high risk for human health and increasing environ-mental burdens Strategic use of biodegradation processingon food waste can turn out into multiple societal benefitsProduction of energy that is biogas through biomass offood waste could be of major interest for easy storage andtransport Secondly it reduces the hazardous effects on envi-ronment through themultiple layered foodwastes processingand management Production of soil additives and liquidfertilizers from organic food waste will be direct incentivefrom food waste management Various 16S and 18S rRNA-based fragmented studieswere performed through researcherfor wastemanagement treatment andmicrobial communitieswere identified from all the three taxonomic units of themicrobial world that is Archaea Bacteria and Eukarya Intotal 4133methanogenic bacteriawere classified intoArchaeadomain and Crenarchaeota and Euryarchaeota are most

visible group [33] Methanogens have huge morphologicaldiversity cocci (Methanococcus) Spirillaceae (Methanospir-illum) Sarcina (Methanosarcina) rods (Methanobacterium)short rods (Methanobrevibacter) and filiforms (Methanoth-rix) [150] Acetotrophic methanogens are the main oblig-atory anaerobes belonging to genus Methanosarcina whichare involved in the processing of acetate to methane andcarbondioxideMethanobacteriaceae family have been foundassociated with hydrogen binding methanogenic bacteriaMethanosphaera stadtmaniae andMethanobrevibacter woliniiare the two main groups of hydrogenotrophic microor-ganisms participating in anaerobic processing of fruit andvegetable [151]

The knowledge of the link between taxonomical andfunctional diversity and species richness can be a key forbetter understanding of ecosystem functioning in waste foodtreatment Molecular methods like PCR RFLP microarraysand sequencing have been utilized in the field of wastemanagement But these methods have own limitations forlarge scale functional characterization of ecological systemsRecently capturedmetagenomics demonstrated the potentialof functional characterization of microbial communities ofagricultural soil on a large scale through NGS Applicationof these approaches for food waste management can improveour understanding about treatment and enhance qualityof treatment and management products [152] Microbialcommunities can be used in more efficient manner infood waste management through exploration of availablemicrobial resources and strategic use of available advancemetagenomics practices

111 Microarrays Microarray is a one of the easiest andpowerful tools to characterize differences in gene con-tent between organisms and gene expression Microar-ray technique has become popular due to large scalesequencing of microbial genomes year after year Hun-dreds of microbial microarray based studies have been

BioMed Research International 11

Table6Bioinformaticstoo

lsanddatabasesu

sedform

icrobialcommun

ityanalysis

Database

Featured

escriptio

nWebopensource

Availability

Microbialgenom

eand

metagenom

icdata

resource

IMG

Integrated

MicrobialGenom

esandMicrobiom

eRe

positoryof

33116geno

med

atasetsa

nd4615

microbiom

edataset

Yesyes

httpsim

gjgid

oegov

MGD

BMicrobialgeno

med

atabasew

ith4742

geno

mes

Yesyes

httpmbgdgeno

mea

djp

ENSE

MBL

Accessto

over

40000

BacterialG

enom

esYesyes

httpbacteriaen

semblorgin

dexhtml

RefSeq

(microbial)

Archaealand

bacterialreposito

ryatNCB

IRe

ferenceS

equence

Yesyes

httpsw

wwncbinlm

nihgovrefseq

Microarraysa

ndgene

expressio

ndatabase

(M3D

)ManyMicrobe

Microarrays

Database

Yesyes

httpm3dm

ssmed

uB120583

GSbase

Microarraydatasetsform

icrobialgene

expressio

nYesyes

httpbu

gssg

ulac

ukbu

gsbaseta

bsexp

erim

entp

hp

COLO

MBO

SCollectionof

bacterialgenee

xpression

compend

ium

Yesyes

httpwwwcolombo

snet

Microbeon

line

Repo

sitoryof

3707

geno

mesgenee

xpressiondata

for113

organism

sYesyes

httpwwwmicrobesonlineo

rg

Taxonomic

Functio

nalA

nnotationandCo

mparativeG

enom

ics

POGO

Databaseo

fPairw

ise-C

omparis

onsO

fGenom

esandOrtho

logous

genes

Yesyes

httppo

goec

edrexeledu

abo

utphp

MicroScope

MicrobialGenom

eAnn

otationampAnalysis

Platform

Yesyes

httpsw

wwgeno

scop

ecnsfragcm

icroscop

eho

me

AGeS

ASoftw

areS

ystem

forM

icrobialGenom

eSequ

ence

Ann

otation

Yesyes

httpwwwbh

saiorgagesh

tml

NMPD

RNationalM

icrobialPathogen

DataR

esou

rcefor

anno

tatio

ncomparativ

egenom

icsw

ithan

emph

asison

thefoo

d-bo

rnep

atho

gens

Yesyes

httpwwwnm

pdro

rgFIG

wikiv

iewcgi

MetaP

athw

ays

Apipelin

efor

taxono

micandfunctio

nal

anno

tatio

nfro

menvironm

entalsequence

inform

ation

Yesyes

httphallamm

icrobiolog

yubcca

MetaPathw

ays

ShotgunF

unctiona

lizeR

anR-packagefor

functio

nalcom

paris

onof

metagenom

es

Yesyes

httpshotgunmathchalmersse

MG-

RAST

automated

analysisplatform

form

etagenom

esbasedon

sequ

ence

data

Yesyes

httpmetagenom

icsa

nlgov

MEG

ANAcomprehensiv

etoo

lbox

forinteractiv

elyanalyzingmicrobiom

edata

Noyes

httpabin

funi-tu

ebingendesoft

waremegan6welc

ome

Metabolicanalysisandmodellingtooland

databases

CellD

esigner

Metabolicpathway

reconstructio

nandsim

ulation

Yesyes

httpwwwcelld

esignero

rg

E-zyme

Predictio

nof

ECnu

mbersfro

mchem

ical

transfo

rmationpatte

rnYesyes

httpwwwgeno

mejptoolse-zyme

Trito

nTo

olforE

nzym

eEng

ineerin

gYesyes

wwwncbrm

unicztrito

nEC

MDB

EcoliMetabolmed

atabase

Yesyes

httpecmdb

ca

MicrobesFlux

Aweb

platform

forg

enom

erecon

structio

nand

constraint-based

mod

ellin

gYesyes

httpwwwmicrobesflux

org

BioMed Research International 3

Cer

eals

Vege

tabl

esPo

tato

esFr

uits

Rice

Oil

crop

sM

ilkBa

nana

Tom

atoe

sO

nion

sAp

ples

Coc

onut

Pulse

sPi

neap

ple

Mea

t

Total food waste (world)

020000400006000080000

100000120000

Mill

ion

tonn

es

(a)

Vege

tabl

es

Cer

eals

Frui

ts

Rice

Oil

crop

s

Pota

toes

Milk

Bana

na

Tom

atoe

s

Appl

es

Oni

ons

Coc

onut

Pulse

s

Total food waste (Asia)

010000200003000040000500006000070000

Kilo

Ton

nes

(b)

Figure 2 Typical wasted foods in world and in Asia

Food waste mainly consists of carbohydrates proteinslipids and traces of inorganic compounds The compositionvaries in accordance with the type of food waste and itsconstituents Food waste consisting of rice and vegetablesis abundant in carbohydrates while food waste consistingof meat and eggs has high quantity of proteins and lipidsTable 1 summarizes the composition of food waste studied indifferent parts of the globe

2 Anaerobic Digestion

Generation of methane via anaerobic process is an appro-priate solution for food waste management The process haslesser cost and low residual waste production and utilizationof food waste as renewable source of energy [12 13] Table 2summarizes the studies pertaining to anaerobic digestion ofvarious kinds of FWs

Anaerobic digestion consists broadly of three phasesnamely enzymatic hydrolysis acid formation and gas pro-duction Figure 3 depicts the digestion process

21 Enzymatic Hydrolysis In the first phase large polymermolecules that cannot be transported to cell membranes bymicroorganisms are broken down by hydrolases secreted byfacultative or obligate anaerobic hydrolytic bacteria Hydrol-ysis breaks down the polymers into oligomer or monomericunits Polysaccharides are broken down into oligosaccharidesandmonosaccharides for example (1) represents productionof glucosemolecules by starch hydrolysis Proteins are brokendown into peptides and amino acids and lipids are convertedinto glycerol and fatty acid

119899C6H10O5 + 119899H2O 997888rarr 119899C6H12O6 (1)Mittal [42] reported that in the anaerobic conditions thehydrolysis rate is relatively slower than the rate of acidformation and depends on the nature of substrate bacterialconcentration pH and the temperature of the bioreactorOther parameters such as size of the substrate particles pHproduction of enzymes and adsorption of enzymes on thesubstrate particles also affect the hydrolysis rate Bryant [43]reported that Streptococcus and Enterobacter are genera ofanaerobes that are responsible for hydrolysis

22 Acidogenesis Phase In the second phase acidogenesistakes place in which hydrolytic products are fermented tovolatile fatty acids such as acetate propionate butyrate valer-ate and isobutyrate alongwith carbon dioxide hydrogen andammoniaDuring acidification facultative anaerobic bacteriautilize oxygen and carbon creating an anaerobic conditionfor methanogenesis The monomers obtained in phase onebecome substrates for the microbes in phase two where thesubstrates are converted into organic acids by a group ofbacteria

Acetate hydrogen and carbon dioxide can be uti-lized directly for methane production However propionatebutyrate valerate and isobutyrate are introduced for furtherdegradation by syntrophic acetogenic bacteria to form acetateand hydrogen [42ndash44]

23 Acetogenesis Acetogenic bacteria belonging to generaSyntrophomonas and Syntrophobacter [44] convert the acidphase products into acetates (2) and hydrogen Few acetatemolecules are also generated by reduction of carbon diox-ide using hydrogen as an electron source Acetates willfurther be utilized by methanogens in subsequent stepsHowever hydrogen released in the process exerts inhibitoryeffect on microorganisms Therefore in anaerobic digestersacetogenic bacteria live in syntrophic relationship withhydrogenotrophic methanogens that remove the hydrogenby utilizing it for methane formation Also acetogenesisis the phase which depicts the efficiency of the biogasproduction because 70 of methane arises when acetatereduces Simultaneously 11 hydrogen is also formed duringthe process [44]

119899C6H12O6 997888rarr 3119899CH3COOH (2)

24 Methanogenesis In the last phase methanogenesis takesplace which is carried out by methanogens belonging toArchaea Methane can be produced either by fermentationof acetic acid or by reducing carbon dioxide Therefore theproducts of previous phase that is acetic acid hydrogen andcarbon dioxide act as a precursor for methane formationOnly 30 of methane produced in this process comes from

4 BioMed Research International

Table 1 Composition of FW reported in various literatures

Moisture Total solid Volatile solid Total sugar Starch Cellulose Lipids Protein Ash References759 241 NR 423 293 NR NR 39 13 [14]803 197 954 598 NR 16 157 218 19 [15]828 172 891 627 461 23 181 156 NR [16]752 248 NR 502 461 NR 181 156 23 [16]857 143 982 423 283 NR NR 178 NR [17]828 172 850 627 461 23 181 156 NR [18]613 387 NR 690 NR NR 64 44 12 [19]817 183 875 355 NR NR 241 144 NR [20]815 185 941 550 240 169 140 169 59 [21]819 143 982 483 423 NR NR 178 NR [22]

Table 2 Anaerobic digestion processes of food waste for methane production

Waste Inoculum Vessel type Duration (d) HRT (d) CH4 yield(mlgVS) CH4 References

FW Cow manure Bioreactor with 5 L workingvolume 29 1 530 70 [23]

FW Anaerobic SS Pilot scale 5 tonsd 90 NR 440 70 [24]

FW Anaerobic SS Bioreactor with 12 L workingvolume 60 20 NR 688 [25]

FW SS Bioreactor with 45 L workingvolume 200 1ndash27 520 90 [26]

FW NR 900m3 tank volume 426 80 399 62 [27]FW Anaerobic SS CSTR with 3 L working volume 225 16 455 NR [28]

FW NR Digester with 800ml workingvolume 30 Batch 410 66 [29]

FW Anaerobic SS Batch 28 10ndash28 440 73 [30]FW SS CSTR with 10 L working volume 150 5 464 80 [31]

FW Landfill soil and cowmanure Batch 5 L 60 20ndash60 220 NR [32]

Substrate(i) Carbohydrates(ii) Protein(iii) Fats

Soluble organic

compounds

(i) Sugar(ii) Amino acids(iii) Fatty acids

Acidformation

(i) Alcohols(ii) Carbonic Acid(iii) Volatile fatty acids

Acetic acid formation

Biogas

Hydrolysis

Acetogenesis

Acidogenesis

Methanogenesis

(i) CH4(ii) CO2

(i) CH3COOH(ii) NH3 H2 CO2 NH4 H2S

Figure 3 Anaerobic digestion phases

BioMed Research International 5

Table 3 Microorganism cooperation in organic matter degradation [33 34]

Reaction Type Microorganism Active Genera Product

Fermentation Hydrolytic bacteriaBacteroides Lactobacillus

Propionibacterium SphingomonasSporobacterium Megasphaera

Bifidobacterium

Simple sugars peptidesfatty acids

Acidogenesis Syntropic bacteria Ruminococcus Paenibacillus Clostridium Volatile fatty acids

Acetogenesis Acetogenic bacteria Desulfovibrio AminobacteriumAcidaminococcus CH3COOH

Methanogenesis Methanogens (Archaea)

Methanosaeta MethanolobusMethanococcoides MethanohalophilusMethanosalsus MethanohalobiumHalomethanococcus MethanolaciniaMethanogenium Methanoculleus

CH4

carbon dioxide reduction carried out by methanogens [4546]

CH3COOH 997888rarr CH4 + CO2 (3)

Methane can be generated in two ways by two typesof methanogens (a) acetoclastic methanogens that pro-duce methane from acetic acid and (b) hydrogenotrophicmethanogens that utilize hydrogen to reduce carbon dioxide

CO2 + 4H2 997888rarr CH4 + 3H2O (4)

Table 3 summarizes genera active in anaerobic digestion andthe microorganism cooperation in organic matter degrada-tion

3 Food Waste as a Substrate

Degradability of foodwaste used as substratemainly dependsupon its chemical composition It is quite challenging toknow the exact percentage of different components of thecomplex substrate because of its heterogeneous nature Var-ious researchers have investigated the potential of foodwaste as a substrate for biomethanation Viturtia et al [47]inspected two stages of anaerobic digestion of fruit andvegetable wastes and achieved 951 volatile solids (VS)conversion with a methane yield of 530mLgVS In a studyperformed by Lee et al [23] FWwas converted into methaneusing a 5-L continuous digester resulting in 70 VS conver-sion with a methane yield of 440mLgVS Gunaseelan [24]used around 54 different types of food and reported methaneyield ranged from 180 to 732mLgVS depending on the ori-gin of wastes Cho et al [48] reported 472mlgVS methaneyield with 86 anaerobic biodegradability of the Korean foodwaste Yong et al [49] have reported 0392m3 CH4kg-VSwhen canteen food wastemixed with straw in the ratio of 5 1Food waste as a substrate has potential to provide high biogasyield in comparison to cow manure whey pig manure cornsilage and so forth [50]

4 Key Parameters Affecting Biomethanation

For anaerobes to work with high metabolic activity it isimperative to have controlled environmental conditions Themethanogenic bacteria are very sensitive towards unfavorablesurvival conditions Therefore it is vital to maintain optimalcondition to flourish the process of methanation Biometha-nation process primarily depends upon seeding temperaturepH carbon-nitrogen (CN) ratio volatile fatty acids (VFAs)organic loading rate (OLR) alkalinity total volatile solids(VS) and hydraulic retention time (HRT) and nutrientsconcentration It was also reported that the concentrationsof water soluble material such as sugar amino acids proteinandminerals decrease andwater nonsolublematerials such aslignin cellulose and hemicellulose increase in content [51]

41 Seeding Seeding may speed up the stabilization of thedigestion process The most commonly used materials forinoculation are digested sludge from sewage plant landfillsoil and cow dung slurry

It was reported that the use of goat rumen fluid [52] asinoculum at the rate of 8 (vv) is very efficient for biogasproduction

42 Temperature Methanogenesis has been reported from2∘C in marine sediments to over 100∘C in geothermal areas[53] Methanogens thrive best at around 35∘C (mesophilic)and 55∘C (thermophilic) respectively Environmental tem-perature is also a huge concern for anaerobic microbialculture as change of acetic acid to methane depends mostlyupon temperature It has been reported that the optimumrange of temperature is 35ndash40∘C for mesophilic activity and50ndash65∘C for thermophilic activity [54 55] Bouallagui et al[56] have reported that at 4 total solid methane contentwas found to be 58 65 and 62 at temperatures 20∘C35∘C and 55∘C respectively At 8 total solid methanecontent was found to be 57 and 59 at 35∘C and 55∘Crespectively In a study reported by Kim et al [57] methanecontent was found to be 656 662 674 and 589at temperatures 40∘C 45∘C 50∘C and 55∘C respectively Inanother experiment performed by Gou et al [58] codigestion

6 BioMed Research International

Table 4 CN ratio for some materials

Material N C NAnimal urine 15ndash20 1Cotton stalks 17 30Cow buffalo manure 14ndash3 15ndash40Oat straw flax straw 1ndash12 50ndash60Wheat and rice straw 03ndash05 120ndash150Sawdust 01ndash025 200ndash500

of waste activated sludge with food waste was reported tohave highest gas production rate at 55∘C which was 16 and13 times higher than the gas production at 35∘C and 45∘C

43 pH The pH of bioreactor affects the microbial activityin anaerobic digestion and its efficiency Wang et al [59]reported that optimum pH range is 63ndash78 Initially due toexcess of carbon dioxide pH drops to 62 and after 10 daysit starts rising and stabilizes between 7 and 8 Also Lee etal [60] indicated that optimum range of methanogenesisusing food waste leachate was 65ndash82 The main reasonsfor pH variation are VFAs bicarbonate concentration andalkalinity of the system Goel et al [61] used NaOH andNaHCO3 for controlling pH in anaerobic digestion used forbiomethanation from food waste

44 CarbonNitrogen Ratio Mittal [62] has reported thatdigestion of substrate will proceed more rapidly if the CNratio would be 25ndash30 1 This leads to a conclusion thatbacterial community use up carbon 25ndash30 times faster thannitrogen If the ratio is not adequate the nitrogen wouldget exhausted while there would be some carbon left whichwill cause bacteria to die Excess of nitrogen would lead toammonia formation which will inhibit the digestion processCodigesting dairy manure chicken manure and wheat strawyielded maximum methane when CN ratio was 272 withstable pH [59] In another study performed by Zeshan et al[63] anaerobic digestion performed well at CN ratio of 27An optimum amount of carbon content was having positiveeffect on avoiding excessive ammonia inhibition [64ndash66]Table 4 [67] summarizes the CN ratio of a few selected feedstock

45 Volatile Fatty Acids (VFAs) It has been reported that theproduction and accumulation of volatile fatty acid (VFAs)could show inhibitory and detrimental effects on anaerobicdigestion process which could lead to slow production of bio-gas [68ndash70] VFAs inhibition on the activity of methanogensis caused by a pH drop which may lead to the activity loss ofacid-sensitive enzymes [71] Also high levels of undissociatedacids which can penetrate cell membranes may damagemacromolecules [72]The concentration of VFA in anaerobicdigestion for the solid state of food wastes could rise up to20 gL which is much higher than that in a wastewater anaer-obic process [73] In the optimum conditions required formetabolic activity VFAs range in between 2000ndash3000mgL[74]

46 Organic Loading Rate (OLR) Organic loading rate sim-ply refers to quantity of feed processed per unit volume ofreactor per day Taiganides [75] had reported that controlleddigestion is attained when the loading rate is between 05 kgand 2 kg of total VSm3d In an experiment conducted byNagao et al [76] the volumetric biogas production rateincreased to approximately 27 42 58 and 66 LLd as OLRincreased to 37 55 74 and 92 kg-VS m3d respectively andwas maintained at the same At the highest OLR (129 kg-VSm3d) the volumetric gas production rate decreased belowthe gas production rate at OLR of 74 kg-VS m3d In a studyperformed for comparing autoclaved and untreated foodwaste [77] highest methane yield was obtained at organicloading rate of 3 kgVSm3d for untreated food waste andat 4 kgVSm3d for autoclaved food waste The study wasconducted at 2 3 4 and 6 kgVSm3d Agyeman and Tao[78] digested food waste with dairy manure anaerobicallyat different organic loading rates and reported that bio-gas production rate increased by 101ndash116 when OLR wasincreased from 1 to 2 gVSLd and only by 25ndash38 whenOLR was further increased from 2 to 3 gVSLd Specificmethane yield peaked at the OLR of 2 gVSLd in thedigesters with fine andmedium food waste Also codigestionof food waste with activated sludge was performed in bothmesophilic and thermophilic anaerobic systems at differentOLR The thermophilic system exhibited the best load bear-ing capacity at extremely high OLR of 7 gVSLd while themesophilic system showed the best process stability at lowOLRs (lt5 gVSLd) [79]

For a given size of biogas plant there would be anoptimum loading rate beyond which further loading will notbe fruitful as it may lead to accumulation of excess VFAs andresults in a collapsed reactor [80]

47 Ammonia Biodegradation of protein or other nitrogen-rich substrate produces ammonia and exists in the formof ammonium ion (NH4

+) and NH3 [81 82] It could bebeneficial for the growth of microbes or sometime havedetrimental effect on them [82 83] Ammonia plays a vitalrole in CN ratio and could affect the performance ofdigestion process [59] The reaction between ammonia andVFAs have been reported by Zhang et al [84] and are asfollows

C119909H119910COOH 999445999468 C119909H119910COOminus +H+ (5)

NH3 sdotH2O 999445999468 NH4++OHminus (6)

C119909H119910COOH +NH3 timesH2O

997888rarr C119909H119910COOminus + NH4++H2O

(7)

where C119909H119910COOH represents VFAs

48 Nutrient Microbes use carbon to fulfil energy require-ment and nitrogen for building cell wall structure In addi-tion microbes also need small quantity of micro nutrient[85] such as calcium sodium potassium magnesium andchlorine Also for enzyme synthesis and for maintaining

BioMed Research International 7

enzyme activity heavy metal ions such as Cr Co CuZn and Ni are required in biomethanation [86ndash88] Effectof concentration of sodium potassium and calcium wasobserved during anaerobic digestion activity No inhibitionwas observed when concentration of calcium was increasedup to 7000mgL [89] however optimum concentration wasreported 150ndash300mgL [90] Concentration of heavy metalscould have inhibitory effects on methanogenic activity andinhibition degrees depend upon many factors such as thetotal metal concentration chemical forms of the metals pHand redox potential [91 92]

5 Biochemical Methane Potential (BMP)

Biochemical methane potential is an important assay forelucidation of anaerobic digestion There is an increasedadaptation of BMP assay in recent studies

In an experiment performed for mixed food waste likeboiled rice cabbage and cooked meat which were digestedwith cellulase as control has manifested greater rate ofproduction of methane which is about 472mlgVS with totalreduction in VS up to 86 [48]

In another study performed on canteen waste mixed withstraw in different ratios BMP for food waste and straw was026 and 016m3 CH4kg-VS respectively which shows thatfood waste is easily biodegradable waste while the strawwas difficult to degrade anaerobically which may be due topresence of lignin [49]

Digesting food and vegetables anaerobically yieldedmethanewith aminimumamount of 03 LgVS in every sam-ple which also incorporate as commercial value for anaerobicdigestion [93] In an experiment conducted by Elbeshbishyet al [94] preincubated seed sludge has been used alongwith running seed sludge for BMP test of food waste alongwith primary sludge The maximum methane productionrates using nonincubated inoculum were higher (114mLCH4minusg TCODsub) than those using preincubated inoculum

at all substrate-to-inoculum ratios Lisboa and Lansing [95]codigested four food waste substrates (meatball chickencranberry and ice cream processing wastes) for 69 dayswith flushed dairy manure and have reported an increase inmethane production Their findings suggested that additionof even small quantity of food waste to dairy manure hassignificantly enhanced the BMP levels It was observed thatthe extent of increase in BMP following the addition of foodwaste had wide range starting from 67 to 2940 for ice creamand chicken processing waste respectively

Biogas potential of the dry fraction from pretreatment offood waste from households has been evaluated by Murtoet al [96] A higher methane yield (152 plusmn 22m3ton) wasobtained from digestion of the dry fraction alone Dryfractionmixedwith structuralmaterial produced lower levelsof biogas (112 plusmn 21m3ton) compared to digestion of dryfraction alone

Autoclaved and untreated food waste BMP assay wasperformed byTampio et al [77] Foodwastewas autoclaved at1600∘C 62 bar It has been reported that methane yield at allthe loading rates (2 3 4 and 6 kg-VSm3d) was 5ndash10higherfor untreated food waste which was 0483m3 CH4kgVS as

compared to 0439m3 CH4kgVS obtained from autoclavedfood waste

6 Pretreatment Methods for Food Waste

Anaerobic digestion is now widely embraced to managesolid waste and energy recovery However the recalcitranceimposed by the compositional and structural features offood waste that is degree of polymerisation crystallinitylignin and pectin content accessible surface area and soforth results in limiting the hydrolysis step of anaerobicdigestion such as foodwaste containing uncooked vegetablesthat consist of raw starch that has high degree of crys-tallinity which hinders its hydrolytic degradation Thereforea pretreatment step prior to anaerobic digestion is requiredto increase the degradability of food waste by increasingthe surface area and reducing the degree of polymerisationand crystallinity Pretreatment technologies like mechanicalthermal chemical and biological ones may be applied priorto anaerobic digestion to reduce the crystallinity and enhancethe production of methane using wasted food Researchis earlier carried out to investigate the effect of differentpretreatment methods on anaerobic digestion of food wasteMicrowave pretreatment of food waste with intensity of78∘Cmin resulted in enhanced biogas production and about6 and 24higher COD solubilisation [97] In another studydone by Izumi et al [98] 28 higher biogas production wasobtained using food waste when it is treated with beads millMa et al [99] has used different pretreatment techniques tokitchen waste By addingHCL until the pH reduced to 2 48highermethane productionwas reportedMeanwhile heatingthe same food waste at 120∘C at 1 bar for 30 minutes gave 24higher gas production Again freezing the same food wasteat minus80∘C for 6 h and thawing for 30min result in 56 highergas production Applying pressure of 10 bar followed then bydepressurization produces 48 more biogas

Sometimes intensity of temperature plays a vital role inthermal pretreatment Wang et al [100] have reported thatpretreating food waste at 70∘C for 2 hours results in only269 higher methane production while treating it for 1 hourat 150∘C results in 119 higher gas production Numberof days of pretreatment could result in different rate of gasproduction In an experiment conducted by Stabnikova et al[101] total production of biogas increased up to 237 whenfreozen and thawed for 7 days On the contrary only mereincrease was recorded when it was frozen and thawed for 12days that is 85 In a study when food waste and fruit andvegetable waste heated at 175∘C for 60min this showed 79and 119 decrease in biogas production respectively [102]Food waste (sorted frommunicipal solid waste) when treatedwith electroporation (400 pulses) [79] yielded 20ndash40higherbiogas production due to substrate cell breakage Semiaerobicand anaerobic prehydrolysis of food waste resulted in 95COD destruction with 500mlgVS methane yield [103]Microaeration pretreatment [104] to the codigestion of brownwater and food waste for 4 days with 375ml O2Ld hasshown 21 higher methane yield for inoculated substratewhereas only 10 higher methane yield was observed forsubstrate without the inoculum

8 BioMed Research International

7 Codigestion of Food Waste

Due to high potential for biomethanation food waste isa reliable and promising substrate for anaerobic digestionactivity However longer duration of digestion may some-times lead to inhibition because of improper nutrient balance[105] On the other hand concentration of lipid in foodwaste is always higher than the limited concentration [84106] To restrain this inhibition many strategies have beenadopted by researchers to codigest the food waste with cattlemanure green waste or waste water sludge or with dairywaste Table 5 summarizes the codigestion of FW with otherorganic substrates for improving performance of anaerobicprocess

8 Anaerobic Reactors

To carry out biomethanation in practical manner differenttypes of reactors are required The researchers have useddifferent types of anaerobic reactors such as single stage andtwo-stage reactors semidry reactors solid state anaerobicreactors upflow anaerobic solid state reactors and hybridreactors for the execution of biomethanation process

Configuration of process is quite important for efficiencyofmethane production process For this single stage and two-stage process have been employed for biodegradable wastetreatment Forster-Carneiro et al [30] have reported thatwhen all phases of anaerobic digestion namely hydrolysisacidogenesis acetogenesis and methanogenesis take placesimultaneously in single reactor system encounters fewertechnical failures When all polymeric compounds such ascarbohydrates protein and fat are converted into CH4 H2SNH3 and CO2 in a single vessel then that is termed as singlestage reactor Also stability of single stage anaerobic digesterfor easily degradable FW is a matter of deep concern [23]

Chu et al [107] reported that two-stage anaerobic digesterhas been used to produce both hydrogen and methanein two separate reactors from food waste In this type ofsystem in the first stage acidogens and hydrogen producingmicroorganisms which are having faster growth rate areenriched for hydrogen production and volatile fatty acid Inthe second stage acetogens and methanogens are built upwhere volatile fatty acids are converted into methane andcarbon dioxide

It has been reported that two-stage anaerobic digestionis providing more efficient operation as compared to singlestage Park and Li [65] have reported that highest methanerecovery from kitchen waste when operated in both singlestage and two-stage system was obtained as 90 (based onCOD) which was determined at the OLR of 15 g CODLdIt was also reported by Massanet-Nicolau et al [108] thatmethane yield from food waste increased by 37 in two-stage methane fermentation process The highest methaneyields from FWs were reported by Koike et al [109] Biogasproduction of 850 LgVS during the two-stage hydrogen andmethane production processing of FWwas obtained by them

On the other hand solid state anaerobic digestion hasseveral advantages over liquid anaerobic digestion in terms ofsmaller volume required for reactors low material handling

lowwater requirement and so forth It has been reported thatfood waste is generally treated by liquid anaerobic digestionand organic fraction of municipal solid waste as well aslignocellulosic biomass can be treated by solid state anaerobicdigestion [76]

Hybrid reactors also have been proposed by someresearchers In a study performed by Hai-Lou et al [110]food waste was digested at 35∘C for 16 days in a hybridreactorThe result showed treatment efficiencies of 77ndash80 oftotal organic content removal 59-60 volatile solid removaland 79-80 total COD reduction were achieved Also highmethane content (68ndash70) from the methanogenic phasefavors the application of hybrid anaerobic solid liquid biore-actor to practical solid waste management

9 Mathematical Modelling ofAnaerobic Digestion

Based on the total operating solid content anaerobic diges-tion can be categorized as liquid state anaerobic digestion (L-AD) (TS le 15) or solid state anaerobic digestion (SS-AD)(TSge 15) [111] L-AD is adopted to treat liquid organic wastesuch as sewage sludge animal manure and waste water fromfood processing unit while SS-AD is adopted to treat solidorganic material such as yard trimmings crop residues andorganic fraction of municipal solid waste and food waste [112113] As compared to L-AD SS-AD is having advantages ofsolid loading capacity more volumetric biogas productivityand less need of energy [114]

Besides having economic and environmental benefits andbeing a promising technology a major disadvantage of solidstate anaerobic digestion is the low rate of reaction [115 116]Slow release of soluble substrate for microbial metabolismcould be the possible reason for this Till date SS-AD systemsare operated empirically and still lacking inmechanistic toolsfor controlling the process [117] Application of mathematicalmodel can be applied to anaerobic digestion for mechanismexplanation and its engineering process and parametersaffecting biomethanation and their interaction with eachother [34 118] Many researchers have adopted mathemat-ical modelling for optimizing anaerobic digestion activitybased on theoretical empirical and statistical approach Ina theoretical approach six models were adopted namelytwo-particle model [119] reaction front [120 121] distributedmodel [122ndash126] spatial temporalmodel [127 128] modifiedADM 1 [129ndash131] and diffusion limitation [132] Empiricalapproach leads to logistic modelling [133] and general kineticmodelling [134 135] Also statistical approaches such aslinear regression and artificial neural network have beenadopted [136ndash140]

Statistically derived models may emphasize prediction ofsystem behaviour and are especially useful when there are alimited number of targeting outputs while the models areblack boxmodels andmight not provide enough informationto unveil system mechanisms

On the other hand theoretical models provide moreinsight into the complex system mechanisms while simpli-fication is required to find general applications [34 141]

BioMed Research International 9

Table 5 Codigestion of food waste with other organic substrates

Feedstock Action of codigestion Influencing factor Ref

FW + CM Improve methane yield and systemstability

High buffering capacity and traceelements supplement [29]

FW + livestock waste Improve methane yield and VS reduction Higher buffering capacity [35]FW + yard waste Improve methane yield Less VFA accumulation [36]FW + dewatered sludge Enhance system stability Less inhibition from Na+ [28]FW + sewage sludge Afford high organic loading rate High buffering capacity from ammonia [37]FW + green waste Improve VS reduction CN ratio [38]FW + brown water Improve methane yield High buffering capacity [39]

FW + press water Improved system stability and methaneyield High buffering capacity [40]

FW + distillerrsquos grain Improved biogas production High buffering capacity from ammonia [41]

10 Microbial Community Analysis

Anaerobic digestion is the outcome of complex microbiomeworking in solidarity A guild of microorganisms work ondifferent phases of anaerobic digestion (Figure 4) maintain-ing a synergistic balance to ensure the stability of anaerobicdigestion However anaerobic digesters often suffer withvarious instabilities pertaining to inhibition foaming andacidification especially at high organic load rates (OLRs)[142] These instabilities are generally associated with thecharacteristics and dynamics of the microbial communitiesinvolved in anaerobic digestion process Therefore micro-bial community analysis investigating the composition andbehaviour of microbial communities can be helpful tooptimize stable and efficient process operation The high-throughput sequencing technologies have further opened upnew avenues for investigations of microbial communitiesduring anaerobic digestion Methods for revealing microbialcommunity compositions are based on the generation of16S rRNA gene clone libraries and 16S rRNA ampliconsArchaeal community are identified by targeting mcrA geneThe sequence reads are then analyzed by sophisticated bioin-formatics tools for taxonomic distribution and functionalannotations

Lim and Wang [104] studied microbial community forsingle phase and two-phase anaerobic digestion of food wasteand found predominance of Firmicutes and greater bacterialdiversity in two-phase continuous stirred tank reactor that ledto 23 higher methane yield in comparison to single phaseanaerobic digestion Methanosaeta dominated the archaealcommunity of both single phase and two-phase reactors[143] Cho et al [144] investigated methanogenic communityduring dry anaerobic digestion of food waste and observeda significant reduction in methanogen diversity after accli-mation to dry AD Almost all sequences obtained from dryanaerobic digester sludge belonged toMethanosarcina genusreported to be more tolerant to sudden change in pH anduse both acetoclastic and hydrogenotrophic pathways whichmake them more suitable for surviving in comparison toMethanosaeta Gou et al [58] investigated effect of temper-ature and organic loading rate on microbial community offood waste anaerobic digestion and found significant effect of

temperature on the richness of microbial community whichwas more diverse at 35∘C in comparison to 45∘ and 55∘CAt 55∘C only 5 species remain abundant that explains thatthermophilic bacteria aremore sensitive towards temperaturevariation

Wan et al [145] classified the nucleotide sequences byusing the ribosomal database project classifier software andshowed that Proteobacteria Firmicutes and Bacteroideteswere the most abundant microorganisms during the entireprocess of anaerobic digestion The diversity of microorgan-isms significantly increased during active methanogenesis incomparison to day 0 with addition of Synergistetes Tener-icutes Spirochaetes and Actinobacteria Li et al [142 146]introduced disturbance in OLR into mesophilic anaerobicdigester and carried out microbial community analysis dur-ing stable and deteriorative phases by employing pyrose-quencing Microbial communities were investigated using454 pyrosequencing Raw sequences were quality checked bymothur software and aligned with SILVA alignment In hisstudy the acidogenic bacteria and syntrophic VFA oxidizerswere found abundantly in deteriorative phase suggesting thatduring high OLR hydrolysis and acidogenesis surpassedthe rate of methanogenesis which led to the irreversibleacidification of accumulated VFAs

Zamanzadeh et al [147] investigated the effect of diges-tate recirculation on microbial community by using Illu-mina sequencing Taxonomic assignment of sequences wasdone by using QIIMErsquos uclust-based taxonomy assignerProteobacteria Firmicutes Chloroflexi and Bacteroideteswere found to be the dominant bacterial phyla in bothdigester configuration types (with and without recircula-tion) Methanosaeta and Methanobacterium were dominantgenera among archaeal population accounting for 65 and32 of Euryarchaeotarsquos reads in mesophilic digester withoutrecirculation while in digester with digestate recirculationMethanosaeta accounted for 91 of all EuryarchaeotarsquosTheseresults show the prevalence of acetoclastic methanogens overhydrogenotrophic methanogens which acknowledge acetatereduction as the main pathway of methane formation Simi-larly Gulhane et al [148] studied the microbial communityunder effect of no digestate recirculation 25 digestaterecirculation and 100 digestate recirculation Illumina

10 BioMed Research International

Hydro producing

Homo acetogenic

Hydrolytic bacteria (I)

Methanogenic bacteria (IV)

Acetic acid

Complex organic compound

Organic acidneutral compound

bacteria (III)

CH4CO2

one-carbon compound

H2CO2

acetogenic bacteria (II)

Figure 4 Significance of the microbial population in anaerobic digester

sequenced reads were pair assembled using PANDAseq andmothur software was used to align and filter and trim andremove chimeras and classify and assign taxonomyThe resultrevealed the domination of hydrolytic and fermentative phylain digester with no digestate recirculation while syntrophicacetogenic bacteria dominated the digester with recircula-tion

Guo et al [149] carried out comparative analysis ofthe microbial community response to increasing OLR inmesophilic and thermophilic reactor and reported thatmesophilic reactor had greater richness of microorganismsin comparison to thermophilic reactor They also reportedthe dominance of Methanosaeta in archaeal community inmesophilic reactor while presence of MethanothermobacterandMethanoculleus were favored in thermophilic reactor

11 Metagenomic Tool and Techniques forAdvance Practices

In a fast-growing world food wastage and its managementare one of the major challenges faced by our society due toinherited high risk for human health and increasing environ-mental burdens Strategic use of biodegradation processingon food waste can turn out into multiple societal benefitsProduction of energy that is biogas through biomass offood waste could be of major interest for easy storage andtransport Secondly it reduces the hazardous effects on envi-ronment through themultiple layered foodwastes processingand management Production of soil additives and liquidfertilizers from organic food waste will be direct incentivefrom food waste management Various 16S and 18S rRNA-based fragmented studieswere performed through researcherfor wastemanagement treatment andmicrobial communitieswere identified from all the three taxonomic units of themicrobial world that is Archaea Bacteria and Eukarya Intotal 4133methanogenic bacteriawere classified intoArchaeadomain and Crenarchaeota and Euryarchaeota are most

visible group [33] Methanogens have huge morphologicaldiversity cocci (Methanococcus) Spirillaceae (Methanospir-illum) Sarcina (Methanosarcina) rods (Methanobacterium)short rods (Methanobrevibacter) and filiforms (Methanoth-rix) [150] Acetotrophic methanogens are the main oblig-atory anaerobes belonging to genus Methanosarcina whichare involved in the processing of acetate to methane andcarbondioxideMethanobacteriaceae family have been foundassociated with hydrogen binding methanogenic bacteriaMethanosphaera stadtmaniae andMethanobrevibacter woliniiare the two main groups of hydrogenotrophic microor-ganisms participating in anaerobic processing of fruit andvegetable [151]

The knowledge of the link between taxonomical andfunctional diversity and species richness can be a key forbetter understanding of ecosystem functioning in waste foodtreatment Molecular methods like PCR RFLP microarraysand sequencing have been utilized in the field of wastemanagement But these methods have own limitations forlarge scale functional characterization of ecological systemsRecently capturedmetagenomics demonstrated the potentialof functional characterization of microbial communities ofagricultural soil on a large scale through NGS Applicationof these approaches for food waste management can improveour understanding about treatment and enhance qualityof treatment and management products [152] Microbialcommunities can be used in more efficient manner infood waste management through exploration of availablemicrobial resources and strategic use of available advancemetagenomics practices

111 Microarrays Microarray is a one of the easiest andpowerful tools to characterize differences in gene con-tent between organisms and gene expression Microar-ray technique has become popular due to large scalesequencing of microbial genomes year after year Hun-dreds of microbial microarray based studies have been

BioMed Research International 11

Table6Bioinformaticstoo

lsanddatabasesu

sedform

icrobialcommun

ityanalysis

Database

Featured

escriptio

nWebopensource

Availability

Microbialgenom

eand

metagenom

icdata

resource

IMG

Integrated

MicrobialGenom

esandMicrobiom

eRe

positoryof

33116geno

med

atasetsa

nd4615

microbiom

edataset

Yesyes

httpsim

gjgid

oegov

MGD

BMicrobialgeno

med

atabasew

ith4742

geno

mes

Yesyes

httpmbgdgeno

mea

djp

ENSE

MBL

Accessto

over

40000

BacterialG

enom

esYesyes

httpbacteriaen

semblorgin

dexhtml

RefSeq

(microbial)

Archaealand

bacterialreposito

ryatNCB

IRe

ferenceS

equence

Yesyes

httpsw

wwncbinlm

nihgovrefseq

Microarraysa

ndgene

expressio

ndatabase

(M3D

)ManyMicrobe

Microarrays

Database

Yesyes

httpm3dm

ssmed

uB120583

GSbase

Microarraydatasetsform

icrobialgene

expressio

nYesyes

httpbu

gssg

ulac

ukbu

gsbaseta

bsexp

erim

entp

hp

COLO

MBO

SCollectionof

bacterialgenee

xpression

compend

ium

Yesyes

httpwwwcolombo

snet

Microbeon

line

Repo

sitoryof

3707

geno

mesgenee

xpressiondata

for113

organism

sYesyes

httpwwwmicrobesonlineo

rg

Taxonomic

Functio

nalA

nnotationandCo

mparativeG

enom

ics

POGO

Databaseo

fPairw

ise-C

omparis

onsO

fGenom

esandOrtho

logous

genes

Yesyes

httppo

goec

edrexeledu

abo

utphp

MicroScope

MicrobialGenom

eAnn

otationampAnalysis

Platform

Yesyes

httpsw

wwgeno

scop

ecnsfragcm

icroscop

eho

me

AGeS

ASoftw

areS

ystem

forM

icrobialGenom

eSequ

ence

Ann

otation

Yesyes

httpwwwbh

saiorgagesh

tml

NMPD

RNationalM

icrobialPathogen

DataR

esou

rcefor

anno

tatio

ncomparativ

egenom

icsw

ithan

emph

asison

thefoo

d-bo

rnep

atho

gens

Yesyes

httpwwwnm

pdro

rgFIG

wikiv

iewcgi

MetaP

athw

ays

Apipelin

efor

taxono

micandfunctio

nal

anno

tatio

nfro

menvironm

entalsequence

inform

ation

Yesyes

httphallamm

icrobiolog

yubcca

MetaPathw

ays

ShotgunF

unctiona

lizeR

anR-packagefor

functio

nalcom

paris

onof

metagenom

es

Yesyes

httpshotgunmathchalmersse

MG-

RAST

automated

analysisplatform

form

etagenom

esbasedon

sequ

ence

data

Yesyes

httpmetagenom

icsa

nlgov

MEG

ANAcomprehensiv

etoo

lbox

forinteractiv

elyanalyzingmicrobiom

edata

Noyes

httpabin

funi-tu

ebingendesoft

waremegan6welc

ome

Metabolicanalysisandmodellingtooland

databases

CellD

esigner

Metabolicpathway

reconstructio

nandsim

ulation

Yesyes

httpwwwcelld

esignero

rg

E-zyme

Predictio

nof

ECnu

mbersfro

mchem

ical

transfo

rmationpatte

rnYesyes

httpwwwgeno

mejptoolse-zyme

Trito

nTo

olforE

nzym

eEng

ineerin

gYesyes

wwwncbrm

unicztrito

nEC

MDB

EcoliMetabolmed

atabase

Yesyes

httpecmdb

ca

MicrobesFlux

Aweb

platform

forg

enom

erecon

structio

nand

constraint-based

mod

ellin

gYesyes

httpwwwmicrobesflux

org

4 BioMed Research International

Table 1 Composition of FW reported in various literatures

Moisture Total solid Volatile solid Total sugar Starch Cellulose Lipids Protein Ash References759 241 NR 423 293 NR NR 39 13 [14]803 197 954 598 NR 16 157 218 19 [15]828 172 891 627 461 23 181 156 NR [16]752 248 NR 502 461 NR 181 156 23 [16]857 143 982 423 283 NR NR 178 NR [17]828 172 850 627 461 23 181 156 NR [18]613 387 NR 690 NR NR 64 44 12 [19]817 183 875 355 NR NR 241 144 NR [20]815 185 941 550 240 169 140 169 59 [21]819 143 982 483 423 NR NR 178 NR [22]

Table 2 Anaerobic digestion processes of food waste for methane production

Waste Inoculum Vessel type Duration (d) HRT (d) CH4 yield(mlgVS) CH4 References

FW Cow manure Bioreactor with 5 L workingvolume 29 1 530 70 [23]

FW Anaerobic SS Pilot scale 5 tonsd 90 NR 440 70 [24]

FW Anaerobic SS Bioreactor with 12 L workingvolume 60 20 NR 688 [25]

FW SS Bioreactor with 45 L workingvolume 200 1ndash27 520 90 [26]

FW NR 900m3 tank volume 426 80 399 62 [27]FW Anaerobic SS CSTR with 3 L working volume 225 16 455 NR [28]

FW NR Digester with 800ml workingvolume 30 Batch 410 66 [29]

FW Anaerobic SS Batch 28 10ndash28 440 73 [30]FW SS CSTR with 10 L working volume 150 5 464 80 [31]

FW Landfill soil and cowmanure Batch 5 L 60 20ndash60 220 NR [32]

Substrate(i) Carbohydrates(ii) Protein(iii) Fats

Soluble organic

compounds

(i) Sugar(ii) Amino acids(iii) Fatty acids

Acidformation

(i) Alcohols(ii) Carbonic Acid(iii) Volatile fatty acids

Acetic acid formation

Biogas

Hydrolysis

Acetogenesis

Acidogenesis

Methanogenesis

(i) CH4(ii) CO2

(i) CH3COOH(ii) NH3 H2 CO2 NH4 H2S

Figure 3 Anaerobic digestion phases

BioMed Research International 5

Table 3 Microorganism cooperation in organic matter degradation [33 34]

Reaction Type Microorganism Active Genera Product

Fermentation Hydrolytic bacteriaBacteroides Lactobacillus

Propionibacterium SphingomonasSporobacterium Megasphaera

Bifidobacterium

Simple sugars peptidesfatty acids

Acidogenesis Syntropic bacteria Ruminococcus Paenibacillus Clostridium Volatile fatty acids

Acetogenesis Acetogenic bacteria Desulfovibrio AminobacteriumAcidaminococcus CH3COOH

Methanogenesis Methanogens (Archaea)

Methanosaeta MethanolobusMethanococcoides MethanohalophilusMethanosalsus MethanohalobiumHalomethanococcus MethanolaciniaMethanogenium Methanoculleus

CH4

carbon dioxide reduction carried out by methanogens [4546]

CH3COOH 997888rarr CH4 + CO2 (3)

Methane can be generated in two ways by two typesof methanogens (a) acetoclastic methanogens that pro-duce methane from acetic acid and (b) hydrogenotrophicmethanogens that utilize hydrogen to reduce carbon dioxide

CO2 + 4H2 997888rarr CH4 + 3H2O (4)

Table 3 summarizes genera active in anaerobic digestion andthe microorganism cooperation in organic matter degrada-tion

3 Food Waste as a Substrate

Degradability of foodwaste used as substratemainly dependsupon its chemical composition It is quite challenging toknow the exact percentage of different components of thecomplex substrate because of its heterogeneous nature Var-ious researchers have investigated the potential of foodwaste as a substrate for biomethanation Viturtia et al [47]inspected two stages of anaerobic digestion of fruit andvegetable wastes and achieved 951 volatile solids (VS)conversion with a methane yield of 530mLgVS In a studyperformed by Lee et al [23] FWwas converted into methaneusing a 5-L continuous digester resulting in 70 VS conver-sion with a methane yield of 440mLgVS Gunaseelan [24]used around 54 different types of food and reported methaneyield ranged from 180 to 732mLgVS depending on the ori-gin of wastes Cho et al [48] reported 472mlgVS methaneyield with 86 anaerobic biodegradability of the Korean foodwaste Yong et al [49] have reported 0392m3 CH4kg-VSwhen canteen food wastemixed with straw in the ratio of 5 1Food waste as a substrate has potential to provide high biogasyield in comparison to cow manure whey pig manure cornsilage and so forth [50]

4 Key Parameters Affecting Biomethanation

For anaerobes to work with high metabolic activity it isimperative to have controlled environmental conditions Themethanogenic bacteria are very sensitive towards unfavorablesurvival conditions Therefore it is vital to maintain optimalcondition to flourish the process of methanation Biometha-nation process primarily depends upon seeding temperaturepH carbon-nitrogen (CN) ratio volatile fatty acids (VFAs)organic loading rate (OLR) alkalinity total volatile solids(VS) and hydraulic retention time (HRT) and nutrientsconcentration It was also reported that the concentrationsof water soluble material such as sugar amino acids proteinandminerals decrease andwater nonsolublematerials such aslignin cellulose and hemicellulose increase in content [51]

41 Seeding Seeding may speed up the stabilization of thedigestion process The most commonly used materials forinoculation are digested sludge from sewage plant landfillsoil and cow dung slurry

It was reported that the use of goat rumen fluid [52] asinoculum at the rate of 8 (vv) is very efficient for biogasproduction

42 Temperature Methanogenesis has been reported from2∘C in marine sediments to over 100∘C in geothermal areas[53] Methanogens thrive best at around 35∘C (mesophilic)and 55∘C (thermophilic) respectively Environmental tem-perature is also a huge concern for anaerobic microbialculture as change of acetic acid to methane depends mostlyupon temperature It has been reported that the optimumrange of temperature is 35ndash40∘C for mesophilic activity and50ndash65∘C for thermophilic activity [54 55] Bouallagui et al[56] have reported that at 4 total solid methane contentwas found to be 58 65 and 62 at temperatures 20∘C35∘C and 55∘C respectively At 8 total solid methanecontent was found to be 57 and 59 at 35∘C and 55∘Crespectively In a study reported by Kim et al [57] methanecontent was found to be 656 662 674 and 589at temperatures 40∘C 45∘C 50∘C and 55∘C respectively Inanother experiment performed by Gou et al [58] codigestion

6 BioMed Research International

Table 4 CN ratio for some materials

Material N C NAnimal urine 15ndash20 1Cotton stalks 17 30Cow buffalo manure 14ndash3 15ndash40Oat straw flax straw 1ndash12 50ndash60Wheat and rice straw 03ndash05 120ndash150Sawdust 01ndash025 200ndash500

of waste activated sludge with food waste was reported tohave highest gas production rate at 55∘C which was 16 and13 times higher than the gas production at 35∘C and 45∘C

43 pH The pH of bioreactor affects the microbial activityin anaerobic digestion and its efficiency Wang et al [59]reported that optimum pH range is 63ndash78 Initially due toexcess of carbon dioxide pH drops to 62 and after 10 daysit starts rising and stabilizes between 7 and 8 Also Lee etal [60] indicated that optimum range of methanogenesisusing food waste leachate was 65ndash82 The main reasonsfor pH variation are VFAs bicarbonate concentration andalkalinity of the system Goel et al [61] used NaOH andNaHCO3 for controlling pH in anaerobic digestion used forbiomethanation from food waste

44 CarbonNitrogen Ratio Mittal [62] has reported thatdigestion of substrate will proceed more rapidly if the CNratio would be 25ndash30 1 This leads to a conclusion thatbacterial community use up carbon 25ndash30 times faster thannitrogen If the ratio is not adequate the nitrogen wouldget exhausted while there would be some carbon left whichwill cause bacteria to die Excess of nitrogen would lead toammonia formation which will inhibit the digestion processCodigesting dairy manure chicken manure and wheat strawyielded maximum methane when CN ratio was 272 withstable pH [59] In another study performed by Zeshan et al[63] anaerobic digestion performed well at CN ratio of 27An optimum amount of carbon content was having positiveeffect on avoiding excessive ammonia inhibition [64ndash66]Table 4 [67] summarizes the CN ratio of a few selected feedstock

45 Volatile Fatty Acids (VFAs) It has been reported that theproduction and accumulation of volatile fatty acid (VFAs)could show inhibitory and detrimental effects on anaerobicdigestion process which could lead to slow production of bio-gas [68ndash70] VFAs inhibition on the activity of methanogensis caused by a pH drop which may lead to the activity loss ofacid-sensitive enzymes [71] Also high levels of undissociatedacids which can penetrate cell membranes may damagemacromolecules [72]The concentration of VFA in anaerobicdigestion for the solid state of food wastes could rise up to20 gL which is much higher than that in a wastewater anaer-obic process [73] In the optimum conditions required formetabolic activity VFAs range in between 2000ndash3000mgL[74]

46 Organic Loading Rate (OLR) Organic loading rate sim-ply refers to quantity of feed processed per unit volume ofreactor per day Taiganides [75] had reported that controlleddigestion is attained when the loading rate is between 05 kgand 2 kg of total VSm3d In an experiment conducted byNagao et al [76] the volumetric biogas production rateincreased to approximately 27 42 58 and 66 LLd as OLRincreased to 37 55 74 and 92 kg-VS m3d respectively andwas maintained at the same At the highest OLR (129 kg-VSm3d) the volumetric gas production rate decreased belowthe gas production rate at OLR of 74 kg-VS m3d In a studyperformed for comparing autoclaved and untreated foodwaste [77] highest methane yield was obtained at organicloading rate of 3 kgVSm3d for untreated food waste andat 4 kgVSm3d for autoclaved food waste The study wasconducted at 2 3 4 and 6 kgVSm3d Agyeman and Tao[78] digested food waste with dairy manure anaerobicallyat different organic loading rates and reported that bio-gas production rate increased by 101ndash116 when OLR wasincreased from 1 to 2 gVSLd and only by 25ndash38 whenOLR was further increased from 2 to 3 gVSLd Specificmethane yield peaked at the OLR of 2 gVSLd in thedigesters with fine andmedium food waste Also codigestionof food waste with activated sludge was performed in bothmesophilic and thermophilic anaerobic systems at differentOLR The thermophilic system exhibited the best load bear-ing capacity at extremely high OLR of 7 gVSLd while themesophilic system showed the best process stability at lowOLRs (lt5 gVSLd) [79]

For a given size of biogas plant there would be anoptimum loading rate beyond which further loading will notbe fruitful as it may lead to accumulation of excess VFAs andresults in a collapsed reactor [80]

47 Ammonia Biodegradation of protein or other nitrogen-rich substrate produces ammonia and exists in the formof ammonium ion (NH4

+) and NH3 [81 82] It could bebeneficial for the growth of microbes or sometime havedetrimental effect on them [82 83] Ammonia plays a vitalrole in CN ratio and could affect the performance ofdigestion process [59] The reaction between ammonia andVFAs have been reported by Zhang et al [84] and are asfollows

C119909H119910COOH 999445999468 C119909H119910COOminus +H+ (5)

NH3 sdotH2O 999445999468 NH4++OHminus (6)

C119909H119910COOH +NH3 timesH2O

997888rarr C119909H119910COOminus + NH4++H2O

(7)

where C119909H119910COOH represents VFAs

48 Nutrient Microbes use carbon to fulfil energy require-ment and nitrogen for building cell wall structure In addi-tion microbes also need small quantity of micro nutrient[85] such as calcium sodium potassium magnesium andchlorine Also for enzyme synthesis and for maintaining

BioMed Research International 7

enzyme activity heavy metal ions such as Cr Co CuZn and Ni are required in biomethanation [86ndash88] Effectof concentration of sodium potassium and calcium wasobserved during anaerobic digestion activity No inhibitionwas observed when concentration of calcium was increasedup to 7000mgL [89] however optimum concentration wasreported 150ndash300mgL [90] Concentration of heavy metalscould have inhibitory effects on methanogenic activity andinhibition degrees depend upon many factors such as thetotal metal concentration chemical forms of the metals pHand redox potential [91 92]

5 Biochemical Methane Potential (BMP)

Biochemical methane potential is an important assay forelucidation of anaerobic digestion There is an increasedadaptation of BMP assay in recent studies

In an experiment performed for mixed food waste likeboiled rice cabbage and cooked meat which were digestedwith cellulase as control has manifested greater rate ofproduction of methane which is about 472mlgVS with totalreduction in VS up to 86 [48]

In another study performed on canteen waste mixed withstraw in different ratios BMP for food waste and straw was026 and 016m3 CH4kg-VS respectively which shows thatfood waste is easily biodegradable waste while the strawwas difficult to degrade anaerobically which may be due topresence of lignin [49]

Digesting food and vegetables anaerobically yieldedmethanewith aminimumamount of 03 LgVS in every sam-ple which also incorporate as commercial value for anaerobicdigestion [93] In an experiment conducted by Elbeshbishyet al [94] preincubated seed sludge has been used alongwith running seed sludge for BMP test of food waste alongwith primary sludge The maximum methane productionrates using nonincubated inoculum were higher (114mLCH4minusg TCODsub) than those using preincubated inoculum

at all substrate-to-inoculum ratios Lisboa and Lansing [95]codigested four food waste substrates (meatball chickencranberry and ice cream processing wastes) for 69 dayswith flushed dairy manure and have reported an increase inmethane production Their findings suggested that additionof even small quantity of food waste to dairy manure hassignificantly enhanced the BMP levels It was observed thatthe extent of increase in BMP following the addition of foodwaste had wide range starting from 67 to 2940 for ice creamand chicken processing waste respectively

Biogas potential of the dry fraction from pretreatment offood waste from households has been evaluated by Murtoet al [96] A higher methane yield (152 plusmn 22m3ton) wasobtained from digestion of the dry fraction alone Dryfractionmixedwith structuralmaterial produced lower levelsof biogas (112 plusmn 21m3ton) compared to digestion of dryfraction alone

Autoclaved and untreated food waste BMP assay wasperformed byTampio et al [77] Foodwastewas autoclaved at1600∘C 62 bar It has been reported that methane yield at allthe loading rates (2 3 4 and 6 kg-VSm3d) was 5ndash10higherfor untreated food waste which was 0483m3 CH4kgVS as

compared to 0439m3 CH4kgVS obtained from autoclavedfood waste

6 Pretreatment Methods for Food Waste

Anaerobic digestion is now widely embraced to managesolid waste and energy recovery However the recalcitranceimposed by the compositional and structural features offood waste that is degree of polymerisation crystallinitylignin and pectin content accessible surface area and soforth results in limiting the hydrolysis step of anaerobicdigestion such as foodwaste containing uncooked vegetablesthat consist of raw starch that has high degree of crys-tallinity which hinders its hydrolytic degradation Thereforea pretreatment step prior to anaerobic digestion is requiredto increase the degradability of food waste by increasingthe surface area and reducing the degree of polymerisationand crystallinity Pretreatment technologies like mechanicalthermal chemical and biological ones may be applied priorto anaerobic digestion to reduce the crystallinity and enhancethe production of methane using wasted food Researchis earlier carried out to investigate the effect of differentpretreatment methods on anaerobic digestion of food wasteMicrowave pretreatment of food waste with intensity of78∘Cmin resulted in enhanced biogas production and about6 and 24higher COD solubilisation [97] In another studydone by Izumi et al [98] 28 higher biogas production wasobtained using food waste when it is treated with beads millMa et al [99] has used different pretreatment techniques tokitchen waste By addingHCL until the pH reduced to 2 48highermethane productionwas reportedMeanwhile heatingthe same food waste at 120∘C at 1 bar for 30 minutes gave 24higher gas production Again freezing the same food wasteat minus80∘C for 6 h and thawing for 30min result in 56 highergas production Applying pressure of 10 bar followed then bydepressurization produces 48 more biogas

Sometimes intensity of temperature plays a vital role inthermal pretreatment Wang et al [100] have reported thatpretreating food waste at 70∘C for 2 hours results in only269 higher methane production while treating it for 1 hourat 150∘C results in 119 higher gas production Numberof days of pretreatment could result in different rate of gasproduction In an experiment conducted by Stabnikova et al[101] total production of biogas increased up to 237 whenfreozen and thawed for 7 days On the contrary only mereincrease was recorded when it was frozen and thawed for 12days that is 85 In a study when food waste and fruit andvegetable waste heated at 175∘C for 60min this showed 79and 119 decrease in biogas production respectively [102]Food waste (sorted frommunicipal solid waste) when treatedwith electroporation (400 pulses) [79] yielded 20ndash40higherbiogas production due to substrate cell breakage Semiaerobicand anaerobic prehydrolysis of food waste resulted in 95COD destruction with 500mlgVS methane yield [103]Microaeration pretreatment [104] to the codigestion of brownwater and food waste for 4 days with 375ml O2Ld hasshown 21 higher methane yield for inoculated substratewhereas only 10 higher methane yield was observed forsubstrate without the inoculum

8 BioMed Research International

7 Codigestion of Food Waste

Due to high potential for biomethanation food waste isa reliable and promising substrate for anaerobic digestionactivity However longer duration of digestion may some-times lead to inhibition because of improper nutrient balance[105] On the other hand concentration of lipid in foodwaste is always higher than the limited concentration [84106] To restrain this inhibition many strategies have beenadopted by researchers to codigest the food waste with cattlemanure green waste or waste water sludge or with dairywaste Table 5 summarizes the codigestion of FW with otherorganic substrates for improving performance of anaerobicprocess

8 Anaerobic Reactors

To carry out biomethanation in practical manner differenttypes of reactors are required The researchers have useddifferent types of anaerobic reactors such as single stage andtwo-stage reactors semidry reactors solid state anaerobicreactors upflow anaerobic solid state reactors and hybridreactors for the execution of biomethanation process

Configuration of process is quite important for efficiencyofmethane production process For this single stage and two-stage process have been employed for biodegradable wastetreatment Forster-Carneiro et al [30] have reported thatwhen all phases of anaerobic digestion namely hydrolysisacidogenesis acetogenesis and methanogenesis take placesimultaneously in single reactor system encounters fewertechnical failures When all polymeric compounds such ascarbohydrates protein and fat are converted into CH4 H2SNH3 and CO2 in a single vessel then that is termed as singlestage reactor Also stability of single stage anaerobic digesterfor easily degradable FW is a matter of deep concern [23]

Chu et al [107] reported that two-stage anaerobic digesterhas been used to produce both hydrogen and methanein two separate reactors from food waste In this type ofsystem in the first stage acidogens and hydrogen producingmicroorganisms which are having faster growth rate areenriched for hydrogen production and volatile fatty acid Inthe second stage acetogens and methanogens are built upwhere volatile fatty acids are converted into methane andcarbon dioxide

It has been reported that two-stage anaerobic digestionis providing more efficient operation as compared to singlestage Park and Li [65] have reported that highest methanerecovery from kitchen waste when operated in both singlestage and two-stage system was obtained as 90 (based onCOD) which was determined at the OLR of 15 g CODLdIt was also reported by Massanet-Nicolau et al [108] thatmethane yield from food waste increased by 37 in two-stage methane fermentation process The highest methaneyields from FWs were reported by Koike et al [109] Biogasproduction of 850 LgVS during the two-stage hydrogen andmethane production processing of FWwas obtained by them

On the other hand solid state anaerobic digestion hasseveral advantages over liquid anaerobic digestion in terms ofsmaller volume required for reactors low material handling

lowwater requirement and so forth It has been reported thatfood waste is generally treated by liquid anaerobic digestionand organic fraction of municipal solid waste as well aslignocellulosic biomass can be treated by solid state anaerobicdigestion [76]

Hybrid reactors also have been proposed by someresearchers In a study performed by Hai-Lou et al [110]food waste was digested at 35∘C for 16 days in a hybridreactorThe result showed treatment efficiencies of 77ndash80 oftotal organic content removal 59-60 volatile solid removaland 79-80 total COD reduction were achieved Also highmethane content (68ndash70) from the methanogenic phasefavors the application of hybrid anaerobic solid liquid biore-actor to practical solid waste management

9 Mathematical Modelling ofAnaerobic Digestion

Based on the total operating solid content anaerobic diges-tion can be categorized as liquid state anaerobic digestion (L-AD) (TS le 15) or solid state anaerobic digestion (SS-AD)(TSge 15) [111] L-AD is adopted to treat liquid organic wastesuch as sewage sludge animal manure and waste water fromfood processing unit while SS-AD is adopted to treat solidorganic material such as yard trimmings crop residues andorganic fraction of municipal solid waste and food waste [112113] As compared to L-AD SS-AD is having advantages ofsolid loading capacity more volumetric biogas productivityand less need of energy [114]

Besides having economic and environmental benefits andbeing a promising technology a major disadvantage of solidstate anaerobic digestion is the low rate of reaction [115 116]Slow release of soluble substrate for microbial metabolismcould be the possible reason for this Till date SS-AD systemsare operated empirically and still lacking inmechanistic toolsfor controlling the process [117] Application of mathematicalmodel can be applied to anaerobic digestion for mechanismexplanation and its engineering process and parametersaffecting biomethanation and their interaction with eachother [34 118] Many researchers have adopted mathemat-ical modelling for optimizing anaerobic digestion activitybased on theoretical empirical and statistical approach Ina theoretical approach six models were adopted namelytwo-particle model [119] reaction front [120 121] distributedmodel [122ndash126] spatial temporalmodel [127 128] modifiedADM 1 [129ndash131] and diffusion limitation [132] Empiricalapproach leads to logistic modelling [133] and general kineticmodelling [134 135] Also statistical approaches such aslinear regression and artificial neural network have beenadopted [136ndash140]

Statistically derived models may emphasize prediction ofsystem behaviour and are especially useful when there are alimited number of targeting outputs while the models areblack boxmodels andmight not provide enough informationto unveil system mechanisms

On the other hand theoretical models provide moreinsight into the complex system mechanisms while simpli-fication is required to find general applications [34 141]

BioMed Research International 9

Table 5 Codigestion of food waste with other organic substrates

Feedstock Action of codigestion Influencing factor Ref

FW + CM Improve methane yield and systemstability

High buffering capacity and traceelements supplement [29]

FW + livestock waste Improve methane yield and VS reduction Higher buffering capacity [35]FW + yard waste Improve methane yield Less VFA accumulation [36]FW + dewatered sludge Enhance system stability Less inhibition from Na+ [28]FW + sewage sludge Afford high organic loading rate High buffering capacity from ammonia [37]FW + green waste Improve VS reduction CN ratio [38]FW + brown water Improve methane yield High buffering capacity [39]

FW + press water Improved system stability and methaneyield High buffering capacity [40]

FW + distillerrsquos grain Improved biogas production High buffering capacity from ammonia [41]

10 Microbial Community Analysis

Anaerobic digestion is the outcome of complex microbiomeworking in solidarity A guild of microorganisms work ondifferent phases of anaerobic digestion (Figure 4) maintain-ing a synergistic balance to ensure the stability of anaerobicdigestion However anaerobic digesters often suffer withvarious instabilities pertaining to inhibition foaming andacidification especially at high organic load rates (OLRs)[142] These instabilities are generally associated with thecharacteristics and dynamics of the microbial communitiesinvolved in anaerobic digestion process Therefore micro-bial community analysis investigating the composition andbehaviour of microbial communities can be helpful tooptimize stable and efficient process operation The high-throughput sequencing technologies have further opened upnew avenues for investigations of microbial communitiesduring anaerobic digestion Methods for revealing microbialcommunity compositions are based on the generation of16S rRNA gene clone libraries and 16S rRNA ampliconsArchaeal community are identified by targeting mcrA geneThe sequence reads are then analyzed by sophisticated bioin-formatics tools for taxonomic distribution and functionalannotations

Lim and Wang [104] studied microbial community forsingle phase and two-phase anaerobic digestion of food wasteand found predominance of Firmicutes and greater bacterialdiversity in two-phase continuous stirred tank reactor that ledto 23 higher methane yield in comparison to single phaseanaerobic digestion Methanosaeta dominated the archaealcommunity of both single phase and two-phase reactors[143] Cho et al [144] investigated methanogenic communityduring dry anaerobic digestion of food waste and observeda significant reduction in methanogen diversity after accli-mation to dry AD Almost all sequences obtained from dryanaerobic digester sludge belonged toMethanosarcina genusreported to be more tolerant to sudden change in pH anduse both acetoclastic and hydrogenotrophic pathways whichmake them more suitable for surviving in comparison toMethanosaeta Gou et al [58] investigated effect of temper-ature and organic loading rate on microbial community offood waste anaerobic digestion and found significant effect of

temperature on the richness of microbial community whichwas more diverse at 35∘C in comparison to 45∘ and 55∘CAt 55∘C only 5 species remain abundant that explains thatthermophilic bacteria aremore sensitive towards temperaturevariation

Wan et al [145] classified the nucleotide sequences byusing the ribosomal database project classifier software andshowed that Proteobacteria Firmicutes and Bacteroideteswere the most abundant microorganisms during the entireprocess of anaerobic digestion The diversity of microorgan-isms significantly increased during active methanogenesis incomparison to day 0 with addition of Synergistetes Tener-icutes Spirochaetes and Actinobacteria Li et al [142 146]introduced disturbance in OLR into mesophilic anaerobicdigester and carried out microbial community analysis dur-ing stable and deteriorative phases by employing pyrose-quencing Microbial communities were investigated using454 pyrosequencing Raw sequences were quality checked bymothur software and aligned with SILVA alignment In hisstudy the acidogenic bacteria and syntrophic VFA oxidizerswere found abundantly in deteriorative phase suggesting thatduring high OLR hydrolysis and acidogenesis surpassedthe rate of methanogenesis which led to the irreversibleacidification of accumulated VFAs

Zamanzadeh et al [147] investigated the effect of diges-tate recirculation on microbial community by using Illu-mina sequencing Taxonomic assignment of sequences wasdone by using QIIMErsquos uclust-based taxonomy assignerProteobacteria Firmicutes Chloroflexi and Bacteroideteswere found to be the dominant bacterial phyla in bothdigester configuration types (with and without recircula-tion) Methanosaeta and Methanobacterium were dominantgenera among archaeal population accounting for 65 and32 of Euryarchaeotarsquos reads in mesophilic digester withoutrecirculation while in digester with digestate recirculationMethanosaeta accounted for 91 of all EuryarchaeotarsquosTheseresults show the prevalence of acetoclastic methanogens overhydrogenotrophic methanogens which acknowledge acetatereduction as the main pathway of methane formation Simi-larly Gulhane et al [148] studied the microbial communityunder effect of no digestate recirculation 25 digestaterecirculation and 100 digestate recirculation Illumina

10 BioMed Research International

Hydro producing

Homo acetogenic

Hydrolytic bacteria (I)

Methanogenic bacteria (IV)

Acetic acid

Complex organic compound

Organic acidneutral compound

bacteria (III)

CH4CO2

one-carbon compound

H2CO2

acetogenic bacteria (II)

Figure 4 Significance of the microbial population in anaerobic digester

sequenced reads were pair assembled using PANDAseq andmothur software was used to align and filter and trim andremove chimeras and classify and assign taxonomyThe resultrevealed the domination of hydrolytic and fermentative phylain digester with no digestate recirculation while syntrophicacetogenic bacteria dominated the digester with recircula-tion

Guo et al [149] carried out comparative analysis ofthe microbial community response to increasing OLR inmesophilic and thermophilic reactor and reported thatmesophilic reactor had greater richness of microorganismsin comparison to thermophilic reactor They also reportedthe dominance of Methanosaeta in archaeal community inmesophilic reactor while presence of MethanothermobacterandMethanoculleus were favored in thermophilic reactor

11 Metagenomic Tool and Techniques forAdvance Practices

In a fast-growing world food wastage and its managementare one of the major challenges faced by our society due toinherited high risk for human health and increasing environ-mental burdens Strategic use of biodegradation processingon food waste can turn out into multiple societal benefitsProduction of energy that is biogas through biomass offood waste could be of major interest for easy storage andtransport Secondly it reduces the hazardous effects on envi-ronment through themultiple layered foodwastes processingand management Production of soil additives and liquidfertilizers from organic food waste will be direct incentivefrom food waste management Various 16S and 18S rRNA-based fragmented studieswere performed through researcherfor wastemanagement treatment andmicrobial communitieswere identified from all the three taxonomic units of themicrobial world that is Archaea Bacteria and Eukarya Intotal 4133methanogenic bacteriawere classified intoArchaeadomain and Crenarchaeota and Euryarchaeota are most

visible group [33] Methanogens have huge morphologicaldiversity cocci (Methanococcus) Spirillaceae (Methanospir-illum) Sarcina (Methanosarcina) rods (Methanobacterium)short rods (Methanobrevibacter) and filiforms (Methanoth-rix) [150] Acetotrophic methanogens are the main oblig-atory anaerobes belonging to genus Methanosarcina whichare involved in the processing of acetate to methane andcarbondioxideMethanobacteriaceae family have been foundassociated with hydrogen binding methanogenic bacteriaMethanosphaera stadtmaniae andMethanobrevibacter woliniiare the two main groups of hydrogenotrophic microor-ganisms participating in anaerobic processing of fruit andvegetable [151]

The knowledge of the link between taxonomical andfunctional diversity and species richness can be a key forbetter understanding of ecosystem functioning in waste foodtreatment Molecular methods like PCR RFLP microarraysand sequencing have been utilized in the field of wastemanagement But these methods have own limitations forlarge scale functional characterization of ecological systemsRecently capturedmetagenomics demonstrated the potentialof functional characterization of microbial communities ofagricultural soil on a large scale through NGS Applicationof these approaches for food waste management can improveour understanding about treatment and enhance qualityof treatment and management products [152] Microbialcommunities can be used in more efficient manner infood waste management through exploration of availablemicrobial resources and strategic use of available advancemetagenomics practices

111 Microarrays Microarray is a one of the easiest andpowerful tools to characterize differences in gene con-tent between organisms and gene expression Microar-ray technique has become popular due to large scalesequencing of microbial genomes year after year Hun-dreds of microbial microarray based studies have been

BioMed Research International 11

Table6Bioinformaticstoo

lsanddatabasesu

sedform

icrobialcommun

ityanalysis

Database

Featured

escriptio

nWebopensource

Availability

Microbialgenom

eand

metagenom

icdata

resource

IMG

Integrated

MicrobialGenom

esandMicrobiom

eRe

positoryof

33116geno

med

atasetsa

nd4615

microbiom

edataset

Yesyes

httpsim

gjgid

oegov

MGD

BMicrobialgeno

med

atabasew

ith4742

geno

mes

Yesyes

httpmbgdgeno

mea

djp

ENSE

MBL

Accessto

over

40000

BacterialG

enom

esYesyes

httpbacteriaen

semblorgin

dexhtml

RefSeq

(microbial)

Archaealand

bacterialreposito

ryatNCB

IRe

ferenceS

equence

Yesyes

httpsw

wwncbinlm

nihgovrefseq

Microarraysa

ndgene

expressio

ndatabase

(M3D

)ManyMicrobe

Microarrays

Database

Yesyes

httpm3dm

ssmed

uB120583

GSbase

Microarraydatasetsform

icrobialgene

expressio

nYesyes

httpbu

gssg

ulac

ukbu

gsbaseta

bsexp

erim

entp

hp

COLO

MBO

SCollectionof

bacterialgenee

xpression

compend

ium

Yesyes

httpwwwcolombo

snet

Microbeon

line

Repo

sitoryof

3707

geno

mesgenee

xpressiondata

for113

organism

sYesyes

httpwwwmicrobesonlineo

rg

Taxonomic

Functio

nalA

nnotationandCo

mparativeG

enom

ics

POGO

Databaseo

fPairw

ise-C

omparis

onsO

fGenom

esandOrtho

logous

genes

Yesyes

httppo

goec

edrexeledu

abo

utphp

MicroScope

MicrobialGenom

eAnn

otationampAnalysis

Platform

Yesyes

httpsw

wwgeno

scop

ecnsfragcm

icroscop

eho

me

AGeS

ASoftw

areS

ystem

forM

icrobialGenom

eSequ

ence

Ann

otation

Yesyes

httpwwwbh

saiorgagesh

tml

NMPD

RNationalM

icrobialPathogen

DataR

esou

rcefor

anno

tatio

ncomparativ

egenom

icsw

ithan

emph

asison

thefoo

d-bo

rnep

atho

gens

Yesyes

httpwwwnm

pdro

rgFIG

wikiv

iewcgi

MetaP

athw

ays

Apipelin

efor

taxono

micandfunctio

nal

anno

tatio

nfro

menvironm

entalsequence

inform

ation

Yesyes

httphallamm

icrobiolog

yubcca

MetaPathw

ays

ShotgunF

unctiona

lizeR

anR-packagefor

functio

nalcom

paris

onof

metagenom

es

Yesyes

httpshotgunmathchalmersse

MG-

RAST

automated

analysisplatform

form

etagenom

esbasedon

sequ

ence

data

Yesyes

httpmetagenom

icsa

nlgov

MEG

ANAcomprehensiv

etoo

lbox

forinteractiv

elyanalyzingmicrobiom

edata

Noyes

httpabin

funi-tu

ebingendesoft

waremegan6welc

ome

Metabolicanalysisandmodellingtooland

databases

CellD

esigner

Metabolicpathway

reconstructio

nandsim

ulation

Yesyes

httpwwwcelld

esignero

rg

E-zyme

Predictio

nof

ECnu

mbersfro

mchem

ical

transfo

rmationpatte

rnYesyes

httpwwwgeno

mejptoolse-zyme

Trito

nTo

olforE

nzym

eEng

ineerin

gYesyes

wwwncbrm

unicztrito

nEC

MDB

EcoliMetabolmed

atabase

Yesyes

httpecmdb

ca

MicrobesFlux

Aweb

platform

forg

enom

erecon

structio

nand

constraint-based

mod

ellin

gYesyes

httpwwwmicrobesflux

org

BioMed Research International 5

Table 3 Microorganism cooperation in organic matter degradation [33 34]

Reaction Type Microorganism Active Genera Product

Fermentation Hydrolytic bacteriaBacteroides Lactobacillus

Propionibacterium SphingomonasSporobacterium Megasphaera

Bifidobacterium

Simple sugars peptidesfatty acids

Acidogenesis Syntropic bacteria Ruminococcus Paenibacillus Clostridium Volatile fatty acids

Acetogenesis Acetogenic bacteria Desulfovibrio AminobacteriumAcidaminococcus CH3COOH

Methanogenesis Methanogens (Archaea)

Methanosaeta MethanolobusMethanococcoides MethanohalophilusMethanosalsus MethanohalobiumHalomethanococcus MethanolaciniaMethanogenium Methanoculleus

CH4

carbon dioxide reduction carried out by methanogens [4546]

CH3COOH 997888rarr CH4 + CO2 (3)

Methane can be generated in two ways by two typesof methanogens (a) acetoclastic methanogens that pro-duce methane from acetic acid and (b) hydrogenotrophicmethanogens that utilize hydrogen to reduce carbon dioxide

CO2 + 4H2 997888rarr CH4 + 3H2O (4)

Table 3 summarizes genera active in anaerobic digestion andthe microorganism cooperation in organic matter degrada-tion

3 Food Waste as a Substrate

Degradability of foodwaste used as substratemainly dependsupon its chemical composition It is quite challenging toknow the exact percentage of different components of thecomplex substrate because of its heterogeneous nature Var-ious researchers have investigated the potential of foodwaste as a substrate for biomethanation Viturtia et al [47]inspected two stages of anaerobic digestion of fruit andvegetable wastes and achieved 951 volatile solids (VS)conversion with a methane yield of 530mLgVS In a studyperformed by Lee et al [23] FWwas converted into methaneusing a 5-L continuous digester resulting in 70 VS conver-sion with a methane yield of 440mLgVS Gunaseelan [24]used around 54 different types of food and reported methaneyield ranged from 180 to 732mLgVS depending on the ori-gin of wastes Cho et al [48] reported 472mlgVS methaneyield with 86 anaerobic biodegradability of the Korean foodwaste Yong et al [49] have reported 0392m3 CH4kg-VSwhen canteen food wastemixed with straw in the ratio of 5 1Food waste as a substrate has potential to provide high biogasyield in comparison to cow manure whey pig manure cornsilage and so forth [50]

4 Key Parameters Affecting Biomethanation

For anaerobes to work with high metabolic activity it isimperative to have controlled environmental conditions Themethanogenic bacteria are very sensitive towards unfavorablesurvival conditions Therefore it is vital to maintain optimalcondition to flourish the process of methanation Biometha-nation process primarily depends upon seeding temperaturepH carbon-nitrogen (CN) ratio volatile fatty acids (VFAs)organic loading rate (OLR) alkalinity total volatile solids(VS) and hydraulic retention time (HRT) and nutrientsconcentration It was also reported that the concentrationsof water soluble material such as sugar amino acids proteinandminerals decrease andwater nonsolublematerials such aslignin cellulose and hemicellulose increase in content [51]

41 Seeding Seeding may speed up the stabilization of thedigestion process The most commonly used materials forinoculation are digested sludge from sewage plant landfillsoil and cow dung slurry

It was reported that the use of goat rumen fluid [52] asinoculum at the rate of 8 (vv) is very efficient for biogasproduction

42 Temperature Methanogenesis has been reported from2∘C in marine sediments to over 100∘C in geothermal areas[53] Methanogens thrive best at around 35∘C (mesophilic)and 55∘C (thermophilic) respectively Environmental tem-perature is also a huge concern for anaerobic microbialculture as change of acetic acid to methane depends mostlyupon temperature It has been reported that the optimumrange of temperature is 35ndash40∘C for mesophilic activity and50ndash65∘C for thermophilic activity [54 55] Bouallagui et al[56] have reported that at 4 total solid methane contentwas found to be 58 65 and 62 at temperatures 20∘C35∘C and 55∘C respectively At 8 total solid methanecontent was found to be 57 and 59 at 35∘C and 55∘Crespectively In a study reported by Kim et al [57] methanecontent was found to be 656 662 674 and 589at temperatures 40∘C 45∘C 50∘C and 55∘C respectively Inanother experiment performed by Gou et al [58] codigestion

6 BioMed Research International

Table 4 CN ratio for some materials

Material N C NAnimal urine 15ndash20 1Cotton stalks 17 30Cow buffalo manure 14ndash3 15ndash40Oat straw flax straw 1ndash12 50ndash60Wheat and rice straw 03ndash05 120ndash150Sawdust 01ndash025 200ndash500

of waste activated sludge with food waste was reported tohave highest gas production rate at 55∘C which was 16 and13 times higher than the gas production at 35∘C and 45∘C

43 pH The pH of bioreactor affects the microbial activityin anaerobic digestion and its efficiency Wang et al [59]reported that optimum pH range is 63ndash78 Initially due toexcess of carbon dioxide pH drops to 62 and after 10 daysit starts rising and stabilizes between 7 and 8 Also Lee etal [60] indicated that optimum range of methanogenesisusing food waste leachate was 65ndash82 The main reasonsfor pH variation are VFAs bicarbonate concentration andalkalinity of the system Goel et al [61] used NaOH andNaHCO3 for controlling pH in anaerobic digestion used forbiomethanation from food waste

44 CarbonNitrogen Ratio Mittal [62] has reported thatdigestion of substrate will proceed more rapidly if the CNratio would be 25ndash30 1 This leads to a conclusion thatbacterial community use up carbon 25ndash30 times faster thannitrogen If the ratio is not adequate the nitrogen wouldget exhausted while there would be some carbon left whichwill cause bacteria to die Excess of nitrogen would lead toammonia formation which will inhibit the digestion processCodigesting dairy manure chicken manure and wheat strawyielded maximum methane when CN ratio was 272 withstable pH [59] In another study performed by Zeshan et al[63] anaerobic digestion performed well at CN ratio of 27An optimum amount of carbon content was having positiveeffect on avoiding excessive ammonia inhibition [64ndash66]Table 4 [67] summarizes the CN ratio of a few selected feedstock

45 Volatile Fatty Acids (VFAs) It has been reported that theproduction and accumulation of volatile fatty acid (VFAs)could show inhibitory and detrimental effects on anaerobicdigestion process which could lead to slow production of bio-gas [68ndash70] VFAs inhibition on the activity of methanogensis caused by a pH drop which may lead to the activity loss ofacid-sensitive enzymes [71] Also high levels of undissociatedacids which can penetrate cell membranes may damagemacromolecules [72]The concentration of VFA in anaerobicdigestion for the solid state of food wastes could rise up to20 gL which is much higher than that in a wastewater anaer-obic process [73] In the optimum conditions required formetabolic activity VFAs range in between 2000ndash3000mgL[74]

46 Organic Loading Rate (OLR) Organic loading rate sim-ply refers to quantity of feed processed per unit volume ofreactor per day Taiganides [75] had reported that controlleddigestion is attained when the loading rate is between 05 kgand 2 kg of total VSm3d In an experiment conducted byNagao et al [76] the volumetric biogas production rateincreased to approximately 27 42 58 and 66 LLd as OLRincreased to 37 55 74 and 92 kg-VS m3d respectively andwas maintained at the same At the highest OLR (129 kg-VSm3d) the volumetric gas production rate decreased belowthe gas production rate at OLR of 74 kg-VS m3d In a studyperformed for comparing autoclaved and untreated foodwaste [77] highest methane yield was obtained at organicloading rate of 3 kgVSm3d for untreated food waste andat 4 kgVSm3d for autoclaved food waste The study wasconducted at 2 3 4 and 6 kgVSm3d Agyeman and Tao[78] digested food waste with dairy manure anaerobicallyat different organic loading rates and reported that bio-gas production rate increased by 101ndash116 when OLR wasincreased from 1 to 2 gVSLd and only by 25ndash38 whenOLR was further increased from 2 to 3 gVSLd Specificmethane yield peaked at the OLR of 2 gVSLd in thedigesters with fine andmedium food waste Also codigestionof food waste with activated sludge was performed in bothmesophilic and thermophilic anaerobic systems at differentOLR The thermophilic system exhibited the best load bear-ing capacity at extremely high OLR of 7 gVSLd while themesophilic system showed the best process stability at lowOLRs (lt5 gVSLd) [79]

For a given size of biogas plant there would be anoptimum loading rate beyond which further loading will notbe fruitful as it may lead to accumulation of excess VFAs andresults in a collapsed reactor [80]

47 Ammonia Biodegradation of protein or other nitrogen-rich substrate produces ammonia and exists in the formof ammonium ion (NH4

+) and NH3 [81 82] It could bebeneficial for the growth of microbes or sometime havedetrimental effect on them [82 83] Ammonia plays a vitalrole in CN ratio and could affect the performance ofdigestion process [59] The reaction between ammonia andVFAs have been reported by Zhang et al [84] and are asfollows

C119909H119910COOH 999445999468 C119909H119910COOminus +H+ (5)

NH3 sdotH2O 999445999468 NH4++OHminus (6)

C119909H119910COOH +NH3 timesH2O

997888rarr C119909H119910COOminus + NH4++H2O

(7)

where C119909H119910COOH represents VFAs

48 Nutrient Microbes use carbon to fulfil energy require-ment and nitrogen for building cell wall structure In addi-tion microbes also need small quantity of micro nutrient[85] such as calcium sodium potassium magnesium andchlorine Also for enzyme synthesis and for maintaining

BioMed Research International 7

enzyme activity heavy metal ions such as Cr Co CuZn and Ni are required in biomethanation [86ndash88] Effectof concentration of sodium potassium and calcium wasobserved during anaerobic digestion activity No inhibitionwas observed when concentration of calcium was increasedup to 7000mgL [89] however optimum concentration wasreported 150ndash300mgL [90] Concentration of heavy metalscould have inhibitory effects on methanogenic activity andinhibition degrees depend upon many factors such as thetotal metal concentration chemical forms of the metals pHand redox potential [91 92]

5 Biochemical Methane Potential (BMP)

Biochemical methane potential is an important assay forelucidation of anaerobic digestion There is an increasedadaptation of BMP assay in recent studies

In an experiment performed for mixed food waste likeboiled rice cabbage and cooked meat which were digestedwith cellulase as control has manifested greater rate ofproduction of methane which is about 472mlgVS with totalreduction in VS up to 86 [48]

In another study performed on canteen waste mixed withstraw in different ratios BMP for food waste and straw was026 and 016m3 CH4kg-VS respectively which shows thatfood waste is easily biodegradable waste while the strawwas difficult to degrade anaerobically which may be due topresence of lignin [49]

Digesting food and vegetables anaerobically yieldedmethanewith aminimumamount of 03 LgVS in every sam-ple which also incorporate as commercial value for anaerobicdigestion [93] In an experiment conducted by Elbeshbishyet al [94] preincubated seed sludge has been used alongwith running seed sludge for BMP test of food waste alongwith primary sludge The maximum methane productionrates using nonincubated inoculum were higher (114mLCH4minusg TCODsub) than those using preincubated inoculum

at all substrate-to-inoculum ratios Lisboa and Lansing [95]codigested four food waste substrates (meatball chickencranberry and ice cream processing wastes) for 69 dayswith flushed dairy manure and have reported an increase inmethane production Their findings suggested that additionof even small quantity of food waste to dairy manure hassignificantly enhanced the BMP levels It was observed thatthe extent of increase in BMP following the addition of foodwaste had wide range starting from 67 to 2940 for ice creamand chicken processing waste respectively

Biogas potential of the dry fraction from pretreatment offood waste from households has been evaluated by Murtoet al [96] A higher methane yield (152 plusmn 22m3ton) wasobtained from digestion of the dry fraction alone Dryfractionmixedwith structuralmaterial produced lower levelsof biogas (112 plusmn 21m3ton) compared to digestion of dryfraction alone

Autoclaved and untreated food waste BMP assay wasperformed byTampio et al [77] Foodwastewas autoclaved at1600∘C 62 bar It has been reported that methane yield at allthe loading rates (2 3 4 and 6 kg-VSm3d) was 5ndash10higherfor untreated food waste which was 0483m3 CH4kgVS as

compared to 0439m3 CH4kgVS obtained from autoclavedfood waste

6 Pretreatment Methods for Food Waste

Anaerobic digestion is now widely embraced to managesolid waste and energy recovery However the recalcitranceimposed by the compositional and structural features offood waste that is degree of polymerisation crystallinitylignin and pectin content accessible surface area and soforth results in limiting the hydrolysis step of anaerobicdigestion such as foodwaste containing uncooked vegetablesthat consist of raw starch that has high degree of crys-tallinity which hinders its hydrolytic degradation Thereforea pretreatment step prior to anaerobic digestion is requiredto increase the degradability of food waste by increasingthe surface area and reducing the degree of polymerisationand crystallinity Pretreatment technologies like mechanicalthermal chemical and biological ones may be applied priorto anaerobic digestion to reduce the crystallinity and enhancethe production of methane using wasted food Researchis earlier carried out to investigate the effect of differentpretreatment methods on anaerobic digestion of food wasteMicrowave pretreatment of food waste with intensity of78∘Cmin resulted in enhanced biogas production and about6 and 24higher COD solubilisation [97] In another studydone by Izumi et al [98] 28 higher biogas production wasobtained using food waste when it is treated with beads millMa et al [99] has used different pretreatment techniques tokitchen waste By addingHCL until the pH reduced to 2 48highermethane productionwas reportedMeanwhile heatingthe same food waste at 120∘C at 1 bar for 30 minutes gave 24higher gas production Again freezing the same food wasteat minus80∘C for 6 h and thawing for 30min result in 56 highergas production Applying pressure of 10 bar followed then bydepressurization produces 48 more biogas

Sometimes intensity of temperature plays a vital role inthermal pretreatment Wang et al [100] have reported thatpretreating food waste at 70∘C for 2 hours results in only269 higher methane production while treating it for 1 hourat 150∘C results in 119 higher gas production Numberof days of pretreatment could result in different rate of gasproduction In an experiment conducted by Stabnikova et al[101] total production of biogas increased up to 237 whenfreozen and thawed for 7 days On the contrary only mereincrease was recorded when it was frozen and thawed for 12days that is 85 In a study when food waste and fruit andvegetable waste heated at 175∘C for 60min this showed 79and 119 decrease in biogas production respectively [102]Food waste (sorted frommunicipal solid waste) when treatedwith electroporation (400 pulses) [79] yielded 20ndash40higherbiogas production due to substrate cell breakage Semiaerobicand anaerobic prehydrolysis of food waste resulted in 95COD destruction with 500mlgVS methane yield [103]Microaeration pretreatment [104] to the codigestion of brownwater and food waste for 4 days with 375ml O2Ld hasshown 21 higher methane yield for inoculated substratewhereas only 10 higher methane yield was observed forsubstrate without the inoculum

8 BioMed Research International

7 Codigestion of Food Waste

Due to high potential for biomethanation food waste isa reliable and promising substrate for anaerobic digestionactivity However longer duration of digestion may some-times lead to inhibition because of improper nutrient balance[105] On the other hand concentration of lipid in foodwaste is always higher than the limited concentration [84106] To restrain this inhibition many strategies have beenadopted by researchers to codigest the food waste with cattlemanure green waste or waste water sludge or with dairywaste Table 5 summarizes the codigestion of FW with otherorganic substrates for improving performance of anaerobicprocess

8 Anaerobic Reactors

To carry out biomethanation in practical manner differenttypes of reactors are required The researchers have useddifferent types of anaerobic reactors such as single stage andtwo-stage reactors semidry reactors solid state anaerobicreactors upflow anaerobic solid state reactors and hybridreactors for the execution of biomethanation process

Configuration of process is quite important for efficiencyofmethane production process For this single stage and two-stage process have been employed for biodegradable wastetreatment Forster-Carneiro et al [30] have reported thatwhen all phases of anaerobic digestion namely hydrolysisacidogenesis acetogenesis and methanogenesis take placesimultaneously in single reactor system encounters fewertechnical failures When all polymeric compounds such ascarbohydrates protein and fat are converted into CH4 H2SNH3 and CO2 in a single vessel then that is termed as singlestage reactor Also stability of single stage anaerobic digesterfor easily degradable FW is a matter of deep concern [23]

Chu et al [107] reported that two-stage anaerobic digesterhas been used to produce both hydrogen and methanein two separate reactors from food waste In this type ofsystem in the first stage acidogens and hydrogen producingmicroorganisms which are having faster growth rate areenriched for hydrogen production and volatile fatty acid Inthe second stage acetogens and methanogens are built upwhere volatile fatty acids are converted into methane andcarbon dioxide

It has been reported that two-stage anaerobic digestionis providing more efficient operation as compared to singlestage Park and Li [65] have reported that highest methanerecovery from kitchen waste when operated in both singlestage and two-stage system was obtained as 90 (based onCOD) which was determined at the OLR of 15 g CODLdIt was also reported by Massanet-Nicolau et al [108] thatmethane yield from food waste increased by 37 in two-stage methane fermentation process The highest methaneyields from FWs were reported by Koike et al [109] Biogasproduction of 850 LgVS during the two-stage hydrogen andmethane production processing of FWwas obtained by them

On the other hand solid state anaerobic digestion hasseveral advantages over liquid anaerobic digestion in terms ofsmaller volume required for reactors low material handling

lowwater requirement and so forth It has been reported thatfood waste is generally treated by liquid anaerobic digestionand organic fraction of municipal solid waste as well aslignocellulosic biomass can be treated by solid state anaerobicdigestion [76]

Hybrid reactors also have been proposed by someresearchers In a study performed by Hai-Lou et al [110]food waste was digested at 35∘C for 16 days in a hybridreactorThe result showed treatment efficiencies of 77ndash80 oftotal organic content removal 59-60 volatile solid removaland 79-80 total COD reduction were achieved Also highmethane content (68ndash70) from the methanogenic phasefavors the application of hybrid anaerobic solid liquid biore-actor to practical solid waste management

9 Mathematical Modelling ofAnaerobic Digestion

Based on the total operating solid content anaerobic diges-tion can be categorized as liquid state anaerobic digestion (L-AD) (TS le 15) or solid state anaerobic digestion (SS-AD)(TSge 15) [111] L-AD is adopted to treat liquid organic wastesuch as sewage sludge animal manure and waste water fromfood processing unit while SS-AD is adopted to treat solidorganic material such as yard trimmings crop residues andorganic fraction of municipal solid waste and food waste [112113] As compared to L-AD SS-AD is having advantages ofsolid loading capacity more volumetric biogas productivityand less need of energy [114]

Besides having economic and environmental benefits andbeing a promising technology a major disadvantage of solidstate anaerobic digestion is the low rate of reaction [115 116]Slow release of soluble substrate for microbial metabolismcould be the possible reason for this Till date SS-AD systemsare operated empirically and still lacking inmechanistic toolsfor controlling the process [117] Application of mathematicalmodel can be applied to anaerobic digestion for mechanismexplanation and its engineering process and parametersaffecting biomethanation and their interaction with eachother [34 118] Many researchers have adopted mathemat-ical modelling for optimizing anaerobic digestion activitybased on theoretical empirical and statistical approach Ina theoretical approach six models were adopted namelytwo-particle model [119] reaction front [120 121] distributedmodel [122ndash126] spatial temporalmodel [127 128] modifiedADM 1 [129ndash131] and diffusion limitation [132] Empiricalapproach leads to logistic modelling [133] and general kineticmodelling [134 135] Also statistical approaches such aslinear regression and artificial neural network have beenadopted [136ndash140]

Statistically derived models may emphasize prediction ofsystem behaviour and are especially useful when there are alimited number of targeting outputs while the models areblack boxmodels andmight not provide enough informationto unveil system mechanisms

On the other hand theoretical models provide moreinsight into the complex system mechanisms while simpli-fication is required to find general applications [34 141]

BioMed Research International 9

Table 5 Codigestion of food waste with other organic substrates

Feedstock Action of codigestion Influencing factor Ref

FW + CM Improve methane yield and systemstability

High buffering capacity and traceelements supplement [29]

FW + livestock waste Improve methane yield and VS reduction Higher buffering capacity [35]FW + yard waste Improve methane yield Less VFA accumulation [36]FW + dewatered sludge Enhance system stability Less inhibition from Na+ [28]FW + sewage sludge Afford high organic loading rate High buffering capacity from ammonia [37]FW + green waste Improve VS reduction CN ratio [38]FW + brown water Improve methane yield High buffering capacity [39]

FW + press water Improved system stability and methaneyield High buffering capacity [40]

FW + distillerrsquos grain Improved biogas production High buffering capacity from ammonia [41]

10 Microbial Community Analysis

Anaerobic digestion is the outcome of complex microbiomeworking in solidarity A guild of microorganisms work ondifferent phases of anaerobic digestion (Figure 4) maintain-ing a synergistic balance to ensure the stability of anaerobicdigestion However anaerobic digesters often suffer withvarious instabilities pertaining to inhibition foaming andacidification especially at high organic load rates (OLRs)[142] These instabilities are generally associated with thecharacteristics and dynamics of the microbial communitiesinvolved in anaerobic digestion process Therefore micro-bial community analysis investigating the composition andbehaviour of microbial communities can be helpful tooptimize stable and efficient process operation The high-throughput sequencing technologies have further opened upnew avenues for investigations of microbial communitiesduring anaerobic digestion Methods for revealing microbialcommunity compositions are based on the generation of16S rRNA gene clone libraries and 16S rRNA ampliconsArchaeal community are identified by targeting mcrA geneThe sequence reads are then analyzed by sophisticated bioin-formatics tools for taxonomic distribution and functionalannotations

Lim and Wang [104] studied microbial community forsingle phase and two-phase anaerobic digestion of food wasteand found predominance of Firmicutes and greater bacterialdiversity in two-phase continuous stirred tank reactor that ledto 23 higher methane yield in comparison to single phaseanaerobic digestion Methanosaeta dominated the archaealcommunity of both single phase and two-phase reactors[143] Cho et al [144] investigated methanogenic communityduring dry anaerobic digestion of food waste and observeda significant reduction in methanogen diversity after accli-mation to dry AD Almost all sequences obtained from dryanaerobic digester sludge belonged toMethanosarcina genusreported to be more tolerant to sudden change in pH anduse both acetoclastic and hydrogenotrophic pathways whichmake them more suitable for surviving in comparison toMethanosaeta Gou et al [58] investigated effect of temper-ature and organic loading rate on microbial community offood waste anaerobic digestion and found significant effect of

temperature on the richness of microbial community whichwas more diverse at 35∘C in comparison to 45∘ and 55∘CAt 55∘C only 5 species remain abundant that explains thatthermophilic bacteria aremore sensitive towards temperaturevariation

Wan et al [145] classified the nucleotide sequences byusing the ribosomal database project classifier software andshowed that Proteobacteria Firmicutes and Bacteroideteswere the most abundant microorganisms during the entireprocess of anaerobic digestion The diversity of microorgan-isms significantly increased during active methanogenesis incomparison to day 0 with addition of Synergistetes Tener-icutes Spirochaetes and Actinobacteria Li et al [142 146]introduced disturbance in OLR into mesophilic anaerobicdigester and carried out microbial community analysis dur-ing stable and deteriorative phases by employing pyrose-quencing Microbial communities were investigated using454 pyrosequencing Raw sequences were quality checked bymothur software and aligned with SILVA alignment In hisstudy the acidogenic bacteria and syntrophic VFA oxidizerswere found abundantly in deteriorative phase suggesting thatduring high OLR hydrolysis and acidogenesis surpassedthe rate of methanogenesis which led to the irreversibleacidification of accumulated VFAs

Zamanzadeh et al [147] investigated the effect of diges-tate recirculation on microbial community by using Illu-mina sequencing Taxonomic assignment of sequences wasdone by using QIIMErsquos uclust-based taxonomy assignerProteobacteria Firmicutes Chloroflexi and Bacteroideteswere found to be the dominant bacterial phyla in bothdigester configuration types (with and without recircula-tion) Methanosaeta and Methanobacterium were dominantgenera among archaeal population accounting for 65 and32 of Euryarchaeotarsquos reads in mesophilic digester withoutrecirculation while in digester with digestate recirculationMethanosaeta accounted for 91 of all EuryarchaeotarsquosTheseresults show the prevalence of acetoclastic methanogens overhydrogenotrophic methanogens which acknowledge acetatereduction as the main pathway of methane formation Simi-larly Gulhane et al [148] studied the microbial communityunder effect of no digestate recirculation 25 digestaterecirculation and 100 digestate recirculation Illumina

10 BioMed Research International

Hydro producing

Homo acetogenic

Hydrolytic bacteria (I)

Methanogenic bacteria (IV)

Acetic acid

Complex organic compound

Organic acidneutral compound

bacteria (III)

CH4CO2

one-carbon compound

H2CO2

acetogenic bacteria (II)

Figure 4 Significance of the microbial population in anaerobic digester

sequenced reads were pair assembled using PANDAseq andmothur software was used to align and filter and trim andremove chimeras and classify and assign taxonomyThe resultrevealed the domination of hydrolytic and fermentative phylain digester with no digestate recirculation while syntrophicacetogenic bacteria dominated the digester with recircula-tion

Guo et al [149] carried out comparative analysis ofthe microbial community response to increasing OLR inmesophilic and thermophilic reactor and reported thatmesophilic reactor had greater richness of microorganismsin comparison to thermophilic reactor They also reportedthe dominance of Methanosaeta in archaeal community inmesophilic reactor while presence of MethanothermobacterandMethanoculleus were favored in thermophilic reactor

11 Metagenomic Tool and Techniques forAdvance Practices

In a fast-growing world food wastage and its managementare one of the major challenges faced by our society due toinherited high risk for human health and increasing environ-mental burdens Strategic use of biodegradation processingon food waste can turn out into multiple societal benefitsProduction of energy that is biogas through biomass offood waste could be of major interest for easy storage andtransport Secondly it reduces the hazardous effects on envi-ronment through themultiple layered foodwastes processingand management Production of soil additives and liquidfertilizers from organic food waste will be direct incentivefrom food waste management Various 16S and 18S rRNA-based fragmented studieswere performed through researcherfor wastemanagement treatment andmicrobial communitieswere identified from all the three taxonomic units of themicrobial world that is Archaea Bacteria and Eukarya Intotal 4133methanogenic bacteriawere classified intoArchaeadomain and Crenarchaeota and Euryarchaeota are most

visible group [33] Methanogens have huge morphologicaldiversity cocci (Methanococcus) Spirillaceae (Methanospir-illum) Sarcina (Methanosarcina) rods (Methanobacterium)short rods (Methanobrevibacter) and filiforms (Methanoth-rix) [150] Acetotrophic methanogens are the main oblig-atory anaerobes belonging to genus Methanosarcina whichare involved in the processing of acetate to methane andcarbondioxideMethanobacteriaceae family have been foundassociated with hydrogen binding methanogenic bacteriaMethanosphaera stadtmaniae andMethanobrevibacter woliniiare the two main groups of hydrogenotrophic microor-ganisms participating in anaerobic processing of fruit andvegetable [151]

The knowledge of the link between taxonomical andfunctional diversity and species richness can be a key forbetter understanding of ecosystem functioning in waste foodtreatment Molecular methods like PCR RFLP microarraysand sequencing have been utilized in the field of wastemanagement But these methods have own limitations forlarge scale functional characterization of ecological systemsRecently capturedmetagenomics demonstrated the potentialof functional characterization of microbial communities ofagricultural soil on a large scale through NGS Applicationof these approaches for food waste management can improveour understanding about treatment and enhance qualityof treatment and management products [152] Microbialcommunities can be used in more efficient manner infood waste management through exploration of availablemicrobial resources and strategic use of available advancemetagenomics practices

111 Microarrays Microarray is a one of the easiest andpowerful tools to characterize differences in gene con-tent between organisms and gene expression Microar-ray technique has become popular due to large scalesequencing of microbial genomes year after year Hun-dreds of microbial microarray based studies have been

BioMed Research International 11

Table6Bioinformaticstoo

lsanddatabasesu

sedform

icrobialcommun

ityanalysis

Database

Featured

escriptio

nWebopensource

Availability

Microbialgenom

eand

metagenom

icdata

resource

IMG

Integrated

MicrobialGenom

esandMicrobiom

eRe

positoryof

33116geno

med

atasetsa

nd4615

microbiom

edataset

Yesyes

httpsim

gjgid

oegov

MGD

BMicrobialgeno

med

atabasew

ith4742

geno

mes

Yesyes

httpmbgdgeno

mea

djp

ENSE

MBL

Accessto

over

40000

BacterialG

enom

esYesyes

httpbacteriaen

semblorgin

dexhtml

RefSeq

(microbial)

Archaealand

bacterialreposito

ryatNCB

IRe

ferenceS

equence

Yesyes

httpsw

wwncbinlm

nihgovrefseq

Microarraysa

ndgene

expressio

ndatabase

(M3D

)ManyMicrobe

Microarrays

Database

Yesyes

httpm3dm

ssmed

uB120583

GSbase

Microarraydatasetsform

icrobialgene

expressio

nYesyes

httpbu

gssg

ulac

ukbu

gsbaseta

bsexp

erim

entp

hp

COLO

MBO

SCollectionof

bacterialgenee

xpression

compend

ium

Yesyes

httpwwwcolombo

snet

Microbeon

line

Repo

sitoryof

3707

geno

mesgenee

xpressiondata

for113

organism

sYesyes

httpwwwmicrobesonlineo

rg

Taxonomic

Functio

nalA

nnotationandCo

mparativeG

enom

ics

POGO

Databaseo

fPairw

ise-C

omparis

onsO

fGenom

esandOrtho

logous

genes

Yesyes

httppo

goec

edrexeledu

abo

utphp

MicroScope

MicrobialGenom

eAnn

otationampAnalysis

Platform

Yesyes

httpsw

wwgeno

scop

ecnsfragcm

icroscop

eho

me

AGeS

ASoftw

areS

ystem

forM

icrobialGenom

eSequ

ence

Ann

otation

Yesyes

httpwwwbh

saiorgagesh

tml

NMPD

RNationalM

icrobialPathogen

DataR

esou

rcefor

anno

tatio

ncomparativ

egenom

icsw

ithan

emph

asison

thefoo

d-bo

rnep

atho

gens

Yesyes

httpwwwnm

pdro

rgFIG

wikiv

iewcgi

MetaP

athw

ays

Apipelin

efor

taxono

micandfunctio

nal

anno

tatio

nfro

menvironm

entalsequence

inform

ation

Yesyes

httphallamm

icrobiolog

yubcca

MetaPathw

ays

ShotgunF

unctiona

lizeR

anR-packagefor

functio

nalcom

paris

onof

metagenom

es

Yesyes

httpshotgunmathchalmersse

MG-

RAST

automated

analysisplatform

form

etagenom

esbasedon

sequ

ence

data

Yesyes

httpmetagenom

icsa

nlgov

MEG

ANAcomprehensiv

etoo

lbox

forinteractiv

elyanalyzingmicrobiom

edata

Noyes

httpabin

funi-tu

ebingendesoft

waremegan6welc

ome

Metabolicanalysisandmodellingtooland

databases

CellD

esigner

Metabolicpathway

reconstructio

nandsim

ulation

Yesyes

httpwwwcelld

esignero

rg

E-zyme

Predictio

nof

ECnu

mbersfro

mchem

ical

transfo

rmationpatte

rnYesyes

httpwwwgeno

mejptoolse-zyme

Trito

nTo

olforE

nzym

eEng

ineerin

gYesyes

wwwncbrm

unicztrito

nEC

MDB

EcoliMetabolmed

atabase

Yesyes

httpecmdb

ca

MicrobesFlux

Aweb

platform

forg

enom

erecon

structio

nand

constraint-based

mod

ellin

gYesyes

httpwwwmicrobesflux

org

6 BioMed Research International

Table 4 CN ratio for some materials

Material N C NAnimal urine 15ndash20 1Cotton stalks 17 30Cow buffalo manure 14ndash3 15ndash40Oat straw flax straw 1ndash12 50ndash60Wheat and rice straw 03ndash05 120ndash150Sawdust 01ndash025 200ndash500

of waste activated sludge with food waste was reported tohave highest gas production rate at 55∘C which was 16 and13 times higher than the gas production at 35∘C and 45∘C

43 pH The pH of bioreactor affects the microbial activityin anaerobic digestion and its efficiency Wang et al [59]reported that optimum pH range is 63ndash78 Initially due toexcess of carbon dioxide pH drops to 62 and after 10 daysit starts rising and stabilizes between 7 and 8 Also Lee etal [60] indicated that optimum range of methanogenesisusing food waste leachate was 65ndash82 The main reasonsfor pH variation are VFAs bicarbonate concentration andalkalinity of the system Goel et al [61] used NaOH andNaHCO3 for controlling pH in anaerobic digestion used forbiomethanation from food waste

44 CarbonNitrogen Ratio Mittal [62] has reported thatdigestion of substrate will proceed more rapidly if the CNratio would be 25ndash30 1 This leads to a conclusion thatbacterial community use up carbon 25ndash30 times faster thannitrogen If the ratio is not adequate the nitrogen wouldget exhausted while there would be some carbon left whichwill cause bacteria to die Excess of nitrogen would lead toammonia formation which will inhibit the digestion processCodigesting dairy manure chicken manure and wheat strawyielded maximum methane when CN ratio was 272 withstable pH [59] In another study performed by Zeshan et al[63] anaerobic digestion performed well at CN ratio of 27An optimum amount of carbon content was having positiveeffect on avoiding excessive ammonia inhibition [64ndash66]Table 4 [67] summarizes the CN ratio of a few selected feedstock

45 Volatile Fatty Acids (VFAs) It has been reported that theproduction and accumulation of volatile fatty acid (VFAs)could show inhibitory and detrimental effects on anaerobicdigestion process which could lead to slow production of bio-gas [68ndash70] VFAs inhibition on the activity of methanogensis caused by a pH drop which may lead to the activity loss ofacid-sensitive enzymes [71] Also high levels of undissociatedacids which can penetrate cell membranes may damagemacromolecules [72]The concentration of VFA in anaerobicdigestion for the solid state of food wastes could rise up to20 gL which is much higher than that in a wastewater anaer-obic process [73] In the optimum conditions required formetabolic activity VFAs range in between 2000ndash3000mgL[74]

46 Organic Loading Rate (OLR) Organic loading rate sim-ply refers to quantity of feed processed per unit volume ofreactor per day Taiganides [75] had reported that controlleddigestion is attained when the loading rate is between 05 kgand 2 kg of total VSm3d In an experiment conducted byNagao et al [76] the volumetric biogas production rateincreased to approximately 27 42 58 and 66 LLd as OLRincreased to 37 55 74 and 92 kg-VS m3d respectively andwas maintained at the same At the highest OLR (129 kg-VSm3d) the volumetric gas production rate decreased belowthe gas production rate at OLR of 74 kg-VS m3d In a studyperformed for comparing autoclaved and untreated foodwaste [77] highest methane yield was obtained at organicloading rate of 3 kgVSm3d for untreated food waste andat 4 kgVSm3d for autoclaved food waste The study wasconducted at 2 3 4 and 6 kgVSm3d Agyeman and Tao[78] digested food waste with dairy manure anaerobicallyat different organic loading rates and reported that bio-gas production rate increased by 101ndash116 when OLR wasincreased from 1 to 2 gVSLd and only by 25ndash38 whenOLR was further increased from 2 to 3 gVSLd Specificmethane yield peaked at the OLR of 2 gVSLd in thedigesters with fine andmedium food waste Also codigestionof food waste with activated sludge was performed in bothmesophilic and thermophilic anaerobic systems at differentOLR The thermophilic system exhibited the best load bear-ing capacity at extremely high OLR of 7 gVSLd while themesophilic system showed the best process stability at lowOLRs (lt5 gVSLd) [79]

For a given size of biogas plant there would be anoptimum loading rate beyond which further loading will notbe fruitful as it may lead to accumulation of excess VFAs andresults in a collapsed reactor [80]

47 Ammonia Biodegradation of protein or other nitrogen-rich substrate produces ammonia and exists in the formof ammonium ion (NH4

+) and NH3 [81 82] It could bebeneficial for the growth of microbes or sometime havedetrimental effect on them [82 83] Ammonia plays a vitalrole in CN ratio and could affect the performance ofdigestion process [59] The reaction between ammonia andVFAs have been reported by Zhang et al [84] and are asfollows

C119909H119910COOH 999445999468 C119909H119910COOminus +H+ (5)

NH3 sdotH2O 999445999468 NH4++OHminus (6)

C119909H119910COOH +NH3 timesH2O

997888rarr C119909H119910COOminus + NH4++H2O

(7)

where C119909H119910COOH represents VFAs

48 Nutrient Microbes use carbon to fulfil energy require-ment and nitrogen for building cell wall structure In addi-tion microbes also need small quantity of micro nutrient[85] such as calcium sodium potassium magnesium andchlorine Also for enzyme synthesis and for maintaining

BioMed Research International 7

enzyme activity heavy metal ions such as Cr Co CuZn and Ni are required in biomethanation [86ndash88] Effectof concentration of sodium potassium and calcium wasobserved during anaerobic digestion activity No inhibitionwas observed when concentration of calcium was increasedup to 7000mgL [89] however optimum concentration wasreported 150ndash300mgL [90] Concentration of heavy metalscould have inhibitory effects on methanogenic activity andinhibition degrees depend upon many factors such as thetotal metal concentration chemical forms of the metals pHand redox potential [91 92]

5 Biochemical Methane Potential (BMP)

Biochemical methane potential is an important assay forelucidation of anaerobic digestion There is an increasedadaptation of BMP assay in recent studies

In an experiment performed for mixed food waste likeboiled rice cabbage and cooked meat which were digestedwith cellulase as control has manifested greater rate ofproduction of methane which is about 472mlgVS with totalreduction in VS up to 86 [48]

In another study performed on canteen waste mixed withstraw in different ratios BMP for food waste and straw was026 and 016m3 CH4kg-VS respectively which shows thatfood waste is easily biodegradable waste while the strawwas difficult to degrade anaerobically which may be due topresence of lignin [49]

Digesting food and vegetables anaerobically yieldedmethanewith aminimumamount of 03 LgVS in every sam-ple which also incorporate as commercial value for anaerobicdigestion [93] In an experiment conducted by Elbeshbishyet al [94] preincubated seed sludge has been used alongwith running seed sludge for BMP test of food waste alongwith primary sludge The maximum methane productionrates using nonincubated inoculum were higher (114mLCH4minusg TCODsub) than those using preincubated inoculum

at all substrate-to-inoculum ratios Lisboa and Lansing [95]codigested four food waste substrates (meatball chickencranberry and ice cream processing wastes) for 69 dayswith flushed dairy manure and have reported an increase inmethane production Their findings suggested that additionof even small quantity of food waste to dairy manure hassignificantly enhanced the BMP levels It was observed thatthe extent of increase in BMP following the addition of foodwaste had wide range starting from 67 to 2940 for ice creamand chicken processing waste respectively

Biogas potential of the dry fraction from pretreatment offood waste from households has been evaluated by Murtoet al [96] A higher methane yield (152 plusmn 22m3ton) wasobtained from digestion of the dry fraction alone Dryfractionmixedwith structuralmaterial produced lower levelsof biogas (112 plusmn 21m3ton) compared to digestion of dryfraction alone

Autoclaved and untreated food waste BMP assay wasperformed byTampio et al [77] Foodwastewas autoclaved at1600∘C 62 bar It has been reported that methane yield at allthe loading rates (2 3 4 and 6 kg-VSm3d) was 5ndash10higherfor untreated food waste which was 0483m3 CH4kgVS as

compared to 0439m3 CH4kgVS obtained from autoclavedfood waste

6 Pretreatment Methods for Food Waste

Anaerobic digestion is now widely embraced to managesolid waste and energy recovery However the recalcitranceimposed by the compositional and structural features offood waste that is degree of polymerisation crystallinitylignin and pectin content accessible surface area and soforth results in limiting the hydrolysis step of anaerobicdigestion such as foodwaste containing uncooked vegetablesthat consist of raw starch that has high degree of crys-tallinity which hinders its hydrolytic degradation Thereforea pretreatment step prior to anaerobic digestion is requiredto increase the degradability of food waste by increasingthe surface area and reducing the degree of polymerisationand crystallinity Pretreatment technologies like mechanicalthermal chemical and biological ones may be applied priorto anaerobic digestion to reduce the crystallinity and enhancethe production of methane using wasted food Researchis earlier carried out to investigate the effect of differentpretreatment methods on anaerobic digestion of food wasteMicrowave pretreatment of food waste with intensity of78∘Cmin resulted in enhanced biogas production and about6 and 24higher COD solubilisation [97] In another studydone by Izumi et al [98] 28 higher biogas production wasobtained using food waste when it is treated with beads millMa et al [99] has used different pretreatment techniques tokitchen waste By addingHCL until the pH reduced to 2 48highermethane productionwas reportedMeanwhile heatingthe same food waste at 120∘C at 1 bar for 30 minutes gave 24higher gas production Again freezing the same food wasteat minus80∘C for 6 h and thawing for 30min result in 56 highergas production Applying pressure of 10 bar followed then bydepressurization produces 48 more biogas

Sometimes intensity of temperature plays a vital role inthermal pretreatment Wang et al [100] have reported thatpretreating food waste at 70∘C for 2 hours results in only269 higher methane production while treating it for 1 hourat 150∘C results in 119 higher gas production Numberof days of pretreatment could result in different rate of gasproduction In an experiment conducted by Stabnikova et al[101] total production of biogas increased up to 237 whenfreozen and thawed for 7 days On the contrary only mereincrease was recorded when it was frozen and thawed for 12days that is 85 In a study when food waste and fruit andvegetable waste heated at 175∘C for 60min this showed 79and 119 decrease in biogas production respectively [102]Food waste (sorted frommunicipal solid waste) when treatedwith electroporation (400 pulses) [79] yielded 20ndash40higherbiogas production due to substrate cell breakage Semiaerobicand anaerobic prehydrolysis of food waste resulted in 95COD destruction with 500mlgVS methane yield [103]Microaeration pretreatment [104] to the codigestion of brownwater and food waste for 4 days with 375ml O2Ld hasshown 21 higher methane yield for inoculated substratewhereas only 10 higher methane yield was observed forsubstrate without the inoculum

8 BioMed Research International

7 Codigestion of Food Waste

Due to high potential for biomethanation food waste isa reliable and promising substrate for anaerobic digestionactivity However longer duration of digestion may some-times lead to inhibition because of improper nutrient balance[105] On the other hand concentration of lipid in foodwaste is always higher than the limited concentration [84106] To restrain this inhibition many strategies have beenadopted by researchers to codigest the food waste with cattlemanure green waste or waste water sludge or with dairywaste Table 5 summarizes the codigestion of FW with otherorganic substrates for improving performance of anaerobicprocess

8 Anaerobic Reactors

To carry out biomethanation in practical manner differenttypes of reactors are required The researchers have useddifferent types of anaerobic reactors such as single stage andtwo-stage reactors semidry reactors solid state anaerobicreactors upflow anaerobic solid state reactors and hybridreactors for the execution of biomethanation process

Configuration of process is quite important for efficiencyofmethane production process For this single stage and two-stage process have been employed for biodegradable wastetreatment Forster-Carneiro et al [30] have reported thatwhen all phases of anaerobic digestion namely hydrolysisacidogenesis acetogenesis and methanogenesis take placesimultaneously in single reactor system encounters fewertechnical failures When all polymeric compounds such ascarbohydrates protein and fat are converted into CH4 H2SNH3 and CO2 in a single vessel then that is termed as singlestage reactor Also stability of single stage anaerobic digesterfor easily degradable FW is a matter of deep concern [23]

Chu et al [107] reported that two-stage anaerobic digesterhas been used to produce both hydrogen and methanein two separate reactors from food waste In this type ofsystem in the first stage acidogens and hydrogen producingmicroorganisms which are having faster growth rate areenriched for hydrogen production and volatile fatty acid Inthe second stage acetogens and methanogens are built upwhere volatile fatty acids are converted into methane andcarbon dioxide

It has been reported that two-stage anaerobic digestionis providing more efficient operation as compared to singlestage Park and Li [65] have reported that highest methanerecovery from kitchen waste when operated in both singlestage and two-stage system was obtained as 90 (based onCOD) which was determined at the OLR of 15 g CODLdIt was also reported by Massanet-Nicolau et al [108] thatmethane yield from food waste increased by 37 in two-stage methane fermentation process The highest methaneyields from FWs were reported by Koike et al [109] Biogasproduction of 850 LgVS during the two-stage hydrogen andmethane production processing of FWwas obtained by them

On the other hand solid state anaerobic digestion hasseveral advantages over liquid anaerobic digestion in terms ofsmaller volume required for reactors low material handling

lowwater requirement and so forth It has been reported thatfood waste is generally treated by liquid anaerobic digestionand organic fraction of municipal solid waste as well aslignocellulosic biomass can be treated by solid state anaerobicdigestion [76]

Hybrid reactors also have been proposed by someresearchers In a study performed by Hai-Lou et al [110]food waste was digested at 35∘C for 16 days in a hybridreactorThe result showed treatment efficiencies of 77ndash80 oftotal organic content removal 59-60 volatile solid removaland 79-80 total COD reduction were achieved Also highmethane content (68ndash70) from the methanogenic phasefavors the application of hybrid anaerobic solid liquid biore-actor to practical solid waste management

9 Mathematical Modelling ofAnaerobic Digestion

Based on the total operating solid content anaerobic diges-tion can be categorized as liquid state anaerobic digestion (L-AD) (TS le 15) or solid state anaerobic digestion (SS-AD)(TSge 15) [111] L-AD is adopted to treat liquid organic wastesuch as sewage sludge animal manure and waste water fromfood processing unit while SS-AD is adopted to treat solidorganic material such as yard trimmings crop residues andorganic fraction of municipal solid waste and food waste [112113] As compared to L-AD SS-AD is having advantages ofsolid loading capacity more volumetric biogas productivityand less need of energy [114]

Besides having economic and environmental benefits andbeing a promising technology a major disadvantage of solidstate anaerobic digestion is the low rate of reaction [115 116]Slow release of soluble substrate for microbial metabolismcould be the possible reason for this Till date SS-AD systemsare operated empirically and still lacking inmechanistic toolsfor controlling the process [117] Application of mathematicalmodel can be applied to anaerobic digestion for mechanismexplanation and its engineering process and parametersaffecting biomethanation and their interaction with eachother [34 118] Many researchers have adopted mathemat-ical modelling for optimizing anaerobic digestion activitybased on theoretical empirical and statistical approach Ina theoretical approach six models were adopted namelytwo-particle model [119] reaction front [120 121] distributedmodel [122ndash126] spatial temporalmodel [127 128] modifiedADM 1 [129ndash131] and diffusion limitation [132] Empiricalapproach leads to logistic modelling [133] and general kineticmodelling [134 135] Also statistical approaches such aslinear regression and artificial neural network have beenadopted [136ndash140]

Statistically derived models may emphasize prediction ofsystem behaviour and are especially useful when there are alimited number of targeting outputs while the models areblack boxmodels andmight not provide enough informationto unveil system mechanisms

On the other hand theoretical models provide moreinsight into the complex system mechanisms while simpli-fication is required to find general applications [34 141]

BioMed Research International 9

Table 5 Codigestion of food waste with other organic substrates

Feedstock Action of codigestion Influencing factor Ref

FW + CM Improve methane yield and systemstability

High buffering capacity and traceelements supplement [29]

FW + livestock waste Improve methane yield and VS reduction Higher buffering capacity [35]FW + yard waste Improve methane yield Less VFA accumulation [36]FW + dewatered sludge Enhance system stability Less inhibition from Na+ [28]FW + sewage sludge Afford high organic loading rate High buffering capacity from ammonia [37]FW + green waste Improve VS reduction CN ratio [38]FW + brown water Improve methane yield High buffering capacity [39]

FW + press water Improved system stability and methaneyield High buffering capacity [40]

FW + distillerrsquos grain Improved biogas production High buffering capacity from ammonia [41]

10 Microbial Community Analysis

Anaerobic digestion is the outcome of complex microbiomeworking in solidarity A guild of microorganisms work ondifferent phases of anaerobic digestion (Figure 4) maintain-ing a synergistic balance to ensure the stability of anaerobicdigestion However anaerobic digesters often suffer withvarious instabilities pertaining to inhibition foaming andacidification especially at high organic load rates (OLRs)[142] These instabilities are generally associated with thecharacteristics and dynamics of the microbial communitiesinvolved in anaerobic digestion process Therefore micro-bial community analysis investigating the composition andbehaviour of microbial communities can be helpful tooptimize stable and efficient process operation The high-throughput sequencing technologies have further opened upnew avenues for investigations of microbial communitiesduring anaerobic digestion Methods for revealing microbialcommunity compositions are based on the generation of16S rRNA gene clone libraries and 16S rRNA ampliconsArchaeal community are identified by targeting mcrA geneThe sequence reads are then analyzed by sophisticated bioin-formatics tools for taxonomic distribution and functionalannotations

Lim and Wang [104] studied microbial community forsingle phase and two-phase anaerobic digestion of food wasteand found predominance of Firmicutes and greater bacterialdiversity in two-phase continuous stirred tank reactor that ledto 23 higher methane yield in comparison to single phaseanaerobic digestion Methanosaeta dominated the archaealcommunity of both single phase and two-phase reactors[143] Cho et al [144] investigated methanogenic communityduring dry anaerobic digestion of food waste and observeda significant reduction in methanogen diversity after accli-mation to dry AD Almost all sequences obtained from dryanaerobic digester sludge belonged toMethanosarcina genusreported to be more tolerant to sudden change in pH anduse both acetoclastic and hydrogenotrophic pathways whichmake them more suitable for surviving in comparison toMethanosaeta Gou et al [58] investigated effect of temper-ature and organic loading rate on microbial community offood waste anaerobic digestion and found significant effect of

temperature on the richness of microbial community whichwas more diverse at 35∘C in comparison to 45∘ and 55∘CAt 55∘C only 5 species remain abundant that explains thatthermophilic bacteria aremore sensitive towards temperaturevariation

Wan et al [145] classified the nucleotide sequences byusing the ribosomal database project classifier software andshowed that Proteobacteria Firmicutes and Bacteroideteswere the most abundant microorganisms during the entireprocess of anaerobic digestion The diversity of microorgan-isms significantly increased during active methanogenesis incomparison to day 0 with addition of Synergistetes Tener-icutes Spirochaetes and Actinobacteria Li et al [142 146]introduced disturbance in OLR into mesophilic anaerobicdigester and carried out microbial community analysis dur-ing stable and deteriorative phases by employing pyrose-quencing Microbial communities were investigated using454 pyrosequencing Raw sequences were quality checked bymothur software and aligned with SILVA alignment In hisstudy the acidogenic bacteria and syntrophic VFA oxidizerswere found abundantly in deteriorative phase suggesting thatduring high OLR hydrolysis and acidogenesis surpassedthe rate of methanogenesis which led to the irreversibleacidification of accumulated VFAs

Zamanzadeh et al [147] investigated the effect of diges-tate recirculation on microbial community by using Illu-mina sequencing Taxonomic assignment of sequences wasdone by using QIIMErsquos uclust-based taxonomy assignerProteobacteria Firmicutes Chloroflexi and Bacteroideteswere found to be the dominant bacterial phyla in bothdigester configuration types (with and without recircula-tion) Methanosaeta and Methanobacterium were dominantgenera among archaeal population accounting for 65 and32 of Euryarchaeotarsquos reads in mesophilic digester withoutrecirculation while in digester with digestate recirculationMethanosaeta accounted for 91 of all EuryarchaeotarsquosTheseresults show the prevalence of acetoclastic methanogens overhydrogenotrophic methanogens which acknowledge acetatereduction as the main pathway of methane formation Simi-larly Gulhane et al [148] studied the microbial communityunder effect of no digestate recirculation 25 digestaterecirculation and 100 digestate recirculation Illumina

10 BioMed Research International

Hydro producing

Homo acetogenic

Hydrolytic bacteria (I)

Methanogenic bacteria (IV)

Acetic acid

Complex organic compound

Organic acidneutral compound

bacteria (III)

CH4CO2

one-carbon compound

H2CO2

acetogenic bacteria (II)

Figure 4 Significance of the microbial population in anaerobic digester

sequenced reads were pair assembled using PANDAseq andmothur software was used to align and filter and trim andremove chimeras and classify and assign taxonomyThe resultrevealed the domination of hydrolytic and fermentative phylain digester with no digestate recirculation while syntrophicacetogenic bacteria dominated the digester with recircula-tion

Guo et al [149] carried out comparative analysis ofthe microbial community response to increasing OLR inmesophilic and thermophilic reactor and reported thatmesophilic reactor had greater richness of microorganismsin comparison to thermophilic reactor They also reportedthe dominance of Methanosaeta in archaeal community inmesophilic reactor while presence of MethanothermobacterandMethanoculleus were favored in thermophilic reactor

11 Metagenomic Tool and Techniques forAdvance Practices

In a fast-growing world food wastage and its managementare one of the major challenges faced by our society due toinherited high risk for human health and increasing environ-mental burdens Strategic use of biodegradation processingon food waste can turn out into multiple societal benefitsProduction of energy that is biogas through biomass offood waste could be of major interest for easy storage andtransport Secondly it reduces the hazardous effects on envi-ronment through themultiple layered foodwastes processingand management Production of soil additives and liquidfertilizers from organic food waste will be direct incentivefrom food waste management Various 16S and 18S rRNA-based fragmented studieswere performed through researcherfor wastemanagement treatment andmicrobial communitieswere identified from all the three taxonomic units of themicrobial world that is Archaea Bacteria and Eukarya Intotal 4133methanogenic bacteriawere classified intoArchaeadomain and Crenarchaeota and Euryarchaeota are most

visible group [33] Methanogens have huge morphologicaldiversity cocci (Methanococcus) Spirillaceae (Methanospir-illum) Sarcina (Methanosarcina) rods (Methanobacterium)short rods (Methanobrevibacter) and filiforms (Methanoth-rix) [150] Acetotrophic methanogens are the main oblig-atory anaerobes belonging to genus Methanosarcina whichare involved in the processing of acetate to methane andcarbondioxideMethanobacteriaceae family have been foundassociated with hydrogen binding methanogenic bacteriaMethanosphaera stadtmaniae andMethanobrevibacter woliniiare the two main groups of hydrogenotrophic microor-ganisms participating in anaerobic processing of fruit andvegetable [151]

The knowledge of the link between taxonomical andfunctional diversity and species richness can be a key forbetter understanding of ecosystem functioning in waste foodtreatment Molecular methods like PCR RFLP microarraysand sequencing have been utilized in the field of wastemanagement But these methods have own limitations forlarge scale functional characterization of ecological systemsRecently capturedmetagenomics demonstrated the potentialof functional characterization of microbial communities ofagricultural soil on a large scale through NGS Applicationof these approaches for food waste management can improveour understanding about treatment and enhance qualityof treatment and management products [152] Microbialcommunities can be used in more efficient manner infood waste management through exploration of availablemicrobial resources and strategic use of available advancemetagenomics practices

111 Microarrays Microarray is a one of the easiest andpowerful tools to characterize differences in gene con-tent between organisms and gene expression Microar-ray technique has become popular due to large scalesequencing of microbial genomes year after year Hun-dreds of microbial microarray based studies have been

BioMed Research International 11

Table6Bioinformaticstoo

lsanddatabasesu

sedform

icrobialcommun

ityanalysis

Database

Featured

escriptio

nWebopensource

Availability

Microbialgenom

eand

metagenom

icdata

resource

IMG

Integrated

MicrobialGenom

esandMicrobiom

eRe

positoryof

33116geno

med

atasetsa

nd4615

microbiom

edataset

Yesyes

httpsim

gjgid

oegov

MGD

BMicrobialgeno

med

atabasew

ith4742

geno

mes

Yesyes

httpmbgdgeno

mea

djp

ENSE

MBL

Accessto

over

40000

BacterialG

enom

esYesyes

httpbacteriaen

semblorgin

dexhtml

RefSeq

(microbial)

Archaealand

bacterialreposito

ryatNCB

IRe

ferenceS

equence

Yesyes

httpsw

wwncbinlm

nihgovrefseq

Microarraysa

ndgene

expressio

ndatabase

(M3D

)ManyMicrobe

Microarrays

Database

Yesyes

httpm3dm

ssmed

uB120583

GSbase

Microarraydatasetsform

icrobialgene

expressio

nYesyes

httpbu

gssg

ulac

ukbu

gsbaseta

bsexp

erim

entp

hp

COLO

MBO

SCollectionof

bacterialgenee

xpression

compend

ium

Yesyes

httpwwwcolombo

snet

Microbeon

line

Repo

sitoryof

3707

geno

mesgenee

xpressiondata

for113

organism

sYesyes

httpwwwmicrobesonlineo

rg

Taxonomic

Functio

nalA

nnotationandCo

mparativeG

enom

ics

POGO

Databaseo

fPairw

ise-C

omparis

onsO

fGenom

esandOrtho

logous

genes

Yesyes

httppo

goec

edrexeledu

abo

utphp

MicroScope

MicrobialGenom

eAnn

otationampAnalysis

Platform

Yesyes

httpsw

wwgeno

scop

ecnsfragcm

icroscop

eho

me

AGeS

ASoftw

areS

ystem

forM

icrobialGenom

eSequ

ence

Ann

otation

Yesyes

httpwwwbh

saiorgagesh

tml

NMPD

RNationalM

icrobialPathogen

DataR

esou

rcefor

anno

tatio

ncomparativ

egenom

icsw

ithan

emph

asison

thefoo

d-bo

rnep

atho

gens

Yesyes

httpwwwnm

pdro

rgFIG

wikiv

iewcgi

MetaP

athw

ays

Apipelin

efor

taxono

micandfunctio

nal

anno

tatio

nfro

menvironm

entalsequence

inform

ation

Yesyes

httphallamm

icrobiolog

yubcca

MetaPathw

ays

ShotgunF

unctiona

lizeR

anR-packagefor

functio

nalcom

paris

onof

metagenom

es

Yesyes

httpshotgunmathchalmersse

MG-

RAST

automated

analysisplatform

form

etagenom

esbasedon

sequ

ence

data

Yesyes

httpmetagenom

icsa

nlgov

MEG

ANAcomprehensiv

etoo

lbox

forinteractiv

elyanalyzingmicrobiom

edata

Noyes

httpabin

funi-tu

ebingendesoft

waremegan6welc

ome

Metabolicanalysisandmodellingtooland

databases

CellD

esigner

Metabolicpathway

reconstructio

nandsim

ulation

Yesyes

httpwwwcelld

esignero

rg

E-zyme

Predictio

nof

ECnu

mbersfro

mchem

ical

transfo

rmationpatte

rnYesyes

httpwwwgeno

mejptoolse-zyme

Trito

nTo

olforE

nzym

eEng

ineerin

gYesyes

wwwncbrm

unicztrito

nEC

MDB

EcoliMetabolmed

atabase

Yesyes

httpecmdb

ca

MicrobesFlux

Aweb

platform

forg

enom

erecon

structio

nand

constraint-based

mod

ellin

gYesyes

httpwwwmicrobesflux

org

BioMed Research International 7

enzyme activity heavy metal ions such as Cr Co CuZn and Ni are required in biomethanation [86ndash88] Effectof concentration of sodium potassium and calcium wasobserved during anaerobic digestion activity No inhibitionwas observed when concentration of calcium was increasedup to 7000mgL [89] however optimum concentration wasreported 150ndash300mgL [90] Concentration of heavy metalscould have inhibitory effects on methanogenic activity andinhibition degrees depend upon many factors such as thetotal metal concentration chemical forms of the metals pHand redox potential [91 92]

5 Biochemical Methane Potential (BMP)

Biochemical methane potential is an important assay forelucidation of anaerobic digestion There is an increasedadaptation of BMP assay in recent studies

In an experiment performed for mixed food waste likeboiled rice cabbage and cooked meat which were digestedwith cellulase as control has manifested greater rate ofproduction of methane which is about 472mlgVS with totalreduction in VS up to 86 [48]

In another study performed on canteen waste mixed withstraw in different ratios BMP for food waste and straw was026 and 016m3 CH4kg-VS respectively which shows thatfood waste is easily biodegradable waste while the strawwas difficult to degrade anaerobically which may be due topresence of lignin [49]

Digesting food and vegetables anaerobically yieldedmethanewith aminimumamount of 03 LgVS in every sam-ple which also incorporate as commercial value for anaerobicdigestion [93] In an experiment conducted by Elbeshbishyet al [94] preincubated seed sludge has been used alongwith running seed sludge for BMP test of food waste alongwith primary sludge The maximum methane productionrates using nonincubated inoculum were higher (114mLCH4minusg TCODsub) than those using preincubated inoculum

at all substrate-to-inoculum ratios Lisboa and Lansing [95]codigested four food waste substrates (meatball chickencranberry and ice cream processing wastes) for 69 dayswith flushed dairy manure and have reported an increase inmethane production Their findings suggested that additionof even small quantity of food waste to dairy manure hassignificantly enhanced the BMP levels It was observed thatthe extent of increase in BMP following the addition of foodwaste had wide range starting from 67 to 2940 for ice creamand chicken processing waste respectively

Biogas potential of the dry fraction from pretreatment offood waste from households has been evaluated by Murtoet al [96] A higher methane yield (152 plusmn 22m3ton) wasobtained from digestion of the dry fraction alone Dryfractionmixedwith structuralmaterial produced lower levelsof biogas (112 plusmn 21m3ton) compared to digestion of dryfraction alone

Autoclaved and untreated food waste BMP assay wasperformed byTampio et al [77] Foodwastewas autoclaved at1600∘C 62 bar It has been reported that methane yield at allthe loading rates (2 3 4 and 6 kg-VSm3d) was 5ndash10higherfor untreated food waste which was 0483m3 CH4kgVS as

compared to 0439m3 CH4kgVS obtained from autoclavedfood waste

6 Pretreatment Methods for Food Waste

Anaerobic digestion is now widely embraced to managesolid waste and energy recovery However the recalcitranceimposed by the compositional and structural features offood waste that is degree of polymerisation crystallinitylignin and pectin content accessible surface area and soforth results in limiting the hydrolysis step of anaerobicdigestion such as foodwaste containing uncooked vegetablesthat consist of raw starch that has high degree of crys-tallinity which hinders its hydrolytic degradation Thereforea pretreatment step prior to anaerobic digestion is requiredto increase the degradability of food waste by increasingthe surface area and reducing the degree of polymerisationand crystallinity Pretreatment technologies like mechanicalthermal chemical and biological ones may be applied priorto anaerobic digestion to reduce the crystallinity and enhancethe production of methane using wasted food Researchis earlier carried out to investigate the effect of differentpretreatment methods on anaerobic digestion of food wasteMicrowave pretreatment of food waste with intensity of78∘Cmin resulted in enhanced biogas production and about6 and 24higher COD solubilisation [97] In another studydone by Izumi et al [98] 28 higher biogas production wasobtained using food waste when it is treated with beads millMa et al [99] has used different pretreatment techniques tokitchen waste By addingHCL until the pH reduced to 2 48highermethane productionwas reportedMeanwhile heatingthe same food waste at 120∘C at 1 bar for 30 minutes gave 24higher gas production Again freezing the same food wasteat minus80∘C for 6 h and thawing for 30min result in 56 highergas production Applying pressure of 10 bar followed then bydepressurization produces 48 more biogas

Sometimes intensity of temperature plays a vital role inthermal pretreatment Wang et al [100] have reported thatpretreating food waste at 70∘C for 2 hours results in only269 higher methane production while treating it for 1 hourat 150∘C results in 119 higher gas production Numberof days of pretreatment could result in different rate of gasproduction In an experiment conducted by Stabnikova et al[101] total production of biogas increased up to 237 whenfreozen and thawed for 7 days On the contrary only mereincrease was recorded when it was frozen and thawed for 12days that is 85 In a study when food waste and fruit andvegetable waste heated at 175∘C for 60min this showed 79and 119 decrease in biogas production respectively [102]Food waste (sorted frommunicipal solid waste) when treatedwith electroporation (400 pulses) [79] yielded 20ndash40higherbiogas production due to substrate cell breakage Semiaerobicand anaerobic prehydrolysis of food waste resulted in 95COD destruction with 500mlgVS methane yield [103]Microaeration pretreatment [104] to the codigestion of brownwater and food waste for 4 days with 375ml O2Ld hasshown 21 higher methane yield for inoculated substratewhereas only 10 higher methane yield was observed forsubstrate without the inoculum

8 BioMed Research International

7 Codigestion of Food Waste

Due to high potential for biomethanation food waste isa reliable and promising substrate for anaerobic digestionactivity However longer duration of digestion may some-times lead to inhibition because of improper nutrient balance[105] On the other hand concentration of lipid in foodwaste is always higher than the limited concentration [84106] To restrain this inhibition many strategies have beenadopted by researchers to codigest the food waste with cattlemanure green waste or waste water sludge or with dairywaste Table 5 summarizes the codigestion of FW with otherorganic substrates for improving performance of anaerobicprocess

8 Anaerobic Reactors

To carry out biomethanation in practical manner differenttypes of reactors are required The researchers have useddifferent types of anaerobic reactors such as single stage andtwo-stage reactors semidry reactors solid state anaerobicreactors upflow anaerobic solid state reactors and hybridreactors for the execution of biomethanation process

Configuration of process is quite important for efficiencyofmethane production process For this single stage and two-stage process have been employed for biodegradable wastetreatment Forster-Carneiro et al [30] have reported thatwhen all phases of anaerobic digestion namely hydrolysisacidogenesis acetogenesis and methanogenesis take placesimultaneously in single reactor system encounters fewertechnical failures When all polymeric compounds such ascarbohydrates protein and fat are converted into CH4 H2SNH3 and CO2 in a single vessel then that is termed as singlestage reactor Also stability of single stage anaerobic digesterfor easily degradable FW is a matter of deep concern [23]

Chu et al [107] reported that two-stage anaerobic digesterhas been used to produce both hydrogen and methanein two separate reactors from food waste In this type ofsystem in the first stage acidogens and hydrogen producingmicroorganisms which are having faster growth rate areenriched for hydrogen production and volatile fatty acid Inthe second stage acetogens and methanogens are built upwhere volatile fatty acids are converted into methane andcarbon dioxide

It has been reported that two-stage anaerobic digestionis providing more efficient operation as compared to singlestage Park and Li [65] have reported that highest methanerecovery from kitchen waste when operated in both singlestage and two-stage system was obtained as 90 (based onCOD) which was determined at the OLR of 15 g CODLdIt was also reported by Massanet-Nicolau et al [108] thatmethane yield from food waste increased by 37 in two-stage methane fermentation process The highest methaneyields from FWs were reported by Koike et al [109] Biogasproduction of 850 LgVS during the two-stage hydrogen andmethane production processing of FWwas obtained by them

On the other hand solid state anaerobic digestion hasseveral advantages over liquid anaerobic digestion in terms ofsmaller volume required for reactors low material handling

lowwater requirement and so forth It has been reported thatfood waste is generally treated by liquid anaerobic digestionand organic fraction of municipal solid waste as well aslignocellulosic biomass can be treated by solid state anaerobicdigestion [76]

Hybrid reactors also have been proposed by someresearchers In a study performed by Hai-Lou et al [110]food waste was digested at 35∘C for 16 days in a hybridreactorThe result showed treatment efficiencies of 77ndash80 oftotal organic content removal 59-60 volatile solid removaland 79-80 total COD reduction were achieved Also highmethane content (68ndash70) from the methanogenic phasefavors the application of hybrid anaerobic solid liquid biore-actor to practical solid waste management

9 Mathematical Modelling ofAnaerobic Digestion

Based on the total operating solid content anaerobic diges-tion can be categorized as liquid state anaerobic digestion (L-AD) (TS le 15) or solid state anaerobic digestion (SS-AD)(TSge 15) [111] L-AD is adopted to treat liquid organic wastesuch as sewage sludge animal manure and waste water fromfood processing unit while SS-AD is adopted to treat solidorganic material such as yard trimmings crop residues andorganic fraction of municipal solid waste and food waste [112113] As compared to L-AD SS-AD is having advantages ofsolid loading capacity more volumetric biogas productivityand less need of energy [114]

Besides having economic and environmental benefits andbeing a promising technology a major disadvantage of solidstate anaerobic digestion is the low rate of reaction [115 116]Slow release of soluble substrate for microbial metabolismcould be the possible reason for this Till date SS-AD systemsare operated empirically and still lacking inmechanistic toolsfor controlling the process [117] Application of mathematicalmodel can be applied to anaerobic digestion for mechanismexplanation and its engineering process and parametersaffecting biomethanation and their interaction with eachother [34 118] Many researchers have adopted mathemat-ical modelling for optimizing anaerobic digestion activitybased on theoretical empirical and statistical approach Ina theoretical approach six models were adopted namelytwo-particle model [119] reaction front [120 121] distributedmodel [122ndash126] spatial temporalmodel [127 128] modifiedADM 1 [129ndash131] and diffusion limitation [132] Empiricalapproach leads to logistic modelling [133] and general kineticmodelling [134 135] Also statistical approaches such aslinear regression and artificial neural network have beenadopted [136ndash140]

Statistically derived models may emphasize prediction ofsystem behaviour and are especially useful when there are alimited number of targeting outputs while the models areblack boxmodels andmight not provide enough informationto unveil system mechanisms

On the other hand theoretical models provide moreinsight into the complex system mechanisms while simpli-fication is required to find general applications [34 141]

BioMed Research International 9

Table 5 Codigestion of food waste with other organic substrates

Feedstock Action of codigestion Influencing factor Ref

FW + CM Improve methane yield and systemstability

High buffering capacity and traceelements supplement [29]

FW + livestock waste Improve methane yield and VS reduction Higher buffering capacity [35]FW + yard waste Improve methane yield Less VFA accumulation [36]FW + dewatered sludge Enhance system stability Less inhibition from Na+ [28]FW + sewage sludge Afford high organic loading rate High buffering capacity from ammonia [37]FW + green waste Improve VS reduction CN ratio [38]FW + brown water Improve methane yield High buffering capacity [39]

FW + press water Improved system stability and methaneyield High buffering capacity [40]

FW + distillerrsquos grain Improved biogas production High buffering capacity from ammonia [41]

10 Microbial Community Analysis

Anaerobic digestion is the outcome of complex microbiomeworking in solidarity A guild of microorganisms work ondifferent phases of anaerobic digestion (Figure 4) maintain-ing a synergistic balance to ensure the stability of anaerobicdigestion However anaerobic digesters often suffer withvarious instabilities pertaining to inhibition foaming andacidification especially at high organic load rates (OLRs)[142] These instabilities are generally associated with thecharacteristics and dynamics of the microbial communitiesinvolved in anaerobic digestion process Therefore micro-bial community analysis investigating the composition andbehaviour of microbial communities can be helpful tooptimize stable and efficient process operation The high-throughput sequencing technologies have further opened upnew avenues for investigations of microbial communitiesduring anaerobic digestion Methods for revealing microbialcommunity compositions are based on the generation of16S rRNA gene clone libraries and 16S rRNA ampliconsArchaeal community are identified by targeting mcrA geneThe sequence reads are then analyzed by sophisticated bioin-formatics tools for taxonomic distribution and functionalannotations

Lim and Wang [104] studied microbial community forsingle phase and two-phase anaerobic digestion of food wasteand found predominance of Firmicutes and greater bacterialdiversity in two-phase continuous stirred tank reactor that ledto 23 higher methane yield in comparison to single phaseanaerobic digestion Methanosaeta dominated the archaealcommunity of both single phase and two-phase reactors[143] Cho et al [144] investigated methanogenic communityduring dry anaerobic digestion of food waste and observeda significant reduction in methanogen diversity after accli-mation to dry AD Almost all sequences obtained from dryanaerobic digester sludge belonged toMethanosarcina genusreported to be more tolerant to sudden change in pH anduse both acetoclastic and hydrogenotrophic pathways whichmake them more suitable for surviving in comparison toMethanosaeta Gou et al [58] investigated effect of temper-ature and organic loading rate on microbial community offood waste anaerobic digestion and found significant effect of

temperature on the richness of microbial community whichwas more diverse at 35∘C in comparison to 45∘ and 55∘CAt 55∘C only 5 species remain abundant that explains thatthermophilic bacteria aremore sensitive towards temperaturevariation

Wan et al [145] classified the nucleotide sequences byusing the ribosomal database project classifier software andshowed that Proteobacteria Firmicutes and Bacteroideteswere the most abundant microorganisms during the entireprocess of anaerobic digestion The diversity of microorgan-isms significantly increased during active methanogenesis incomparison to day 0 with addition of Synergistetes Tener-icutes Spirochaetes and Actinobacteria Li et al [142 146]introduced disturbance in OLR into mesophilic anaerobicdigester and carried out microbial community analysis dur-ing stable and deteriorative phases by employing pyrose-quencing Microbial communities were investigated using454 pyrosequencing Raw sequences were quality checked bymothur software and aligned with SILVA alignment In hisstudy the acidogenic bacteria and syntrophic VFA oxidizerswere found abundantly in deteriorative phase suggesting thatduring high OLR hydrolysis and acidogenesis surpassedthe rate of methanogenesis which led to the irreversibleacidification of accumulated VFAs

Zamanzadeh et al [147] investigated the effect of diges-tate recirculation on microbial community by using Illu-mina sequencing Taxonomic assignment of sequences wasdone by using QIIMErsquos uclust-based taxonomy assignerProteobacteria Firmicutes Chloroflexi and Bacteroideteswere found to be the dominant bacterial phyla in bothdigester configuration types (with and without recircula-tion) Methanosaeta and Methanobacterium were dominantgenera among archaeal population accounting for 65 and32 of Euryarchaeotarsquos reads in mesophilic digester withoutrecirculation while in digester with digestate recirculationMethanosaeta accounted for 91 of all EuryarchaeotarsquosTheseresults show the prevalence of acetoclastic methanogens overhydrogenotrophic methanogens which acknowledge acetatereduction as the main pathway of methane formation Simi-larly Gulhane et al [148] studied the microbial communityunder effect of no digestate recirculation 25 digestaterecirculation and 100 digestate recirculation Illumina

10 BioMed Research International

Hydro producing

Homo acetogenic

Hydrolytic bacteria (I)

Methanogenic bacteria (IV)

Acetic acid

Complex organic compound

Organic acidneutral compound

bacteria (III)

CH4CO2

one-carbon compound

H2CO2

acetogenic bacteria (II)

Figure 4 Significance of the microbial population in anaerobic digester

sequenced reads were pair assembled using PANDAseq andmothur software was used to align and filter and trim andremove chimeras and classify and assign taxonomyThe resultrevealed the domination of hydrolytic and fermentative phylain digester with no digestate recirculation while syntrophicacetogenic bacteria dominated the digester with recircula-tion

Guo et al [149] carried out comparative analysis ofthe microbial community response to increasing OLR inmesophilic and thermophilic reactor and reported thatmesophilic reactor had greater richness of microorganismsin comparison to thermophilic reactor They also reportedthe dominance of Methanosaeta in archaeal community inmesophilic reactor while presence of MethanothermobacterandMethanoculleus were favored in thermophilic reactor

11 Metagenomic Tool and Techniques forAdvance Practices

In a fast-growing world food wastage and its managementare one of the major challenges faced by our society due toinherited high risk for human health and increasing environ-mental burdens Strategic use of biodegradation processingon food waste can turn out into multiple societal benefitsProduction of energy that is biogas through biomass offood waste could be of major interest for easy storage andtransport Secondly it reduces the hazardous effects on envi-ronment through themultiple layered foodwastes processingand management Production of soil additives and liquidfertilizers from organic food waste will be direct incentivefrom food waste management Various 16S and 18S rRNA-based fragmented studieswere performed through researcherfor wastemanagement treatment andmicrobial communitieswere identified from all the three taxonomic units of themicrobial world that is Archaea Bacteria and Eukarya Intotal 4133methanogenic bacteriawere classified intoArchaeadomain and Crenarchaeota and Euryarchaeota are most

visible group [33] Methanogens have huge morphologicaldiversity cocci (Methanococcus) Spirillaceae (Methanospir-illum) Sarcina (Methanosarcina) rods (Methanobacterium)short rods (Methanobrevibacter) and filiforms (Methanoth-rix) [150] Acetotrophic methanogens are the main oblig-atory anaerobes belonging to genus Methanosarcina whichare involved in the processing of acetate to methane andcarbondioxideMethanobacteriaceae family have been foundassociated with hydrogen binding methanogenic bacteriaMethanosphaera stadtmaniae andMethanobrevibacter woliniiare the two main groups of hydrogenotrophic microor-ganisms participating in anaerobic processing of fruit andvegetable [151]

The knowledge of the link between taxonomical andfunctional diversity and species richness can be a key forbetter understanding of ecosystem functioning in waste foodtreatment Molecular methods like PCR RFLP microarraysand sequencing have been utilized in the field of wastemanagement But these methods have own limitations forlarge scale functional characterization of ecological systemsRecently capturedmetagenomics demonstrated the potentialof functional characterization of microbial communities ofagricultural soil on a large scale through NGS Applicationof these approaches for food waste management can improveour understanding about treatment and enhance qualityof treatment and management products [152] Microbialcommunities can be used in more efficient manner infood waste management through exploration of availablemicrobial resources and strategic use of available advancemetagenomics practices

111 Microarrays Microarray is a one of the easiest andpowerful tools to characterize differences in gene con-tent between organisms and gene expression Microar-ray technique has become popular due to large scalesequencing of microbial genomes year after year Hun-dreds of microbial microarray based studies have been

BioMed Research International 11

Table6Bioinformaticstoo

lsanddatabasesu

sedform

icrobialcommun

ityanalysis

Database

Featured

escriptio

nWebopensource

Availability

Microbialgenom

eand

metagenom

icdata

resource

IMG

Integrated

MicrobialGenom

esandMicrobiom

eRe

positoryof

33116geno

med

atasetsa

nd4615

microbiom

edataset

Yesyes

httpsim

gjgid

oegov

MGD

BMicrobialgeno

med

atabasew

ith4742

geno

mes

Yesyes

httpmbgdgeno

mea

djp

ENSE

MBL

Accessto

over

40000

BacterialG

enom

esYesyes

httpbacteriaen

semblorgin

dexhtml

RefSeq

(microbial)

Archaealand

bacterialreposito

ryatNCB

IRe

ferenceS

equence

Yesyes

httpsw

wwncbinlm

nihgovrefseq

Microarraysa

ndgene

expressio

ndatabase

(M3D

)ManyMicrobe

Microarrays

Database

Yesyes

httpm3dm

ssmed

uB120583

GSbase

Microarraydatasetsform

icrobialgene

expressio

nYesyes

httpbu

gssg

ulac

ukbu

gsbaseta

bsexp

erim

entp

hp

COLO

MBO

SCollectionof

bacterialgenee

xpression

compend

ium

Yesyes

httpwwwcolombo

snet

Microbeon

line

Repo

sitoryof

3707

geno

mesgenee

xpressiondata

for113

organism

sYesyes

httpwwwmicrobesonlineo

rg

Taxonomic

Functio

nalA

nnotationandCo

mparativeG

enom

ics

POGO

Databaseo

fPairw

ise-C

omparis

onsO

fGenom

esandOrtho

logous

genes

Yesyes

httppo

goec

edrexeledu

abo

utphp

MicroScope

MicrobialGenom

eAnn

otationampAnalysis

Platform

Yesyes

httpsw

wwgeno

scop

ecnsfragcm

icroscop

eho

me

AGeS

ASoftw

areS

ystem

forM

icrobialGenom

eSequ

ence

Ann

otation

Yesyes

httpwwwbh

saiorgagesh

tml

NMPD

RNationalM

icrobialPathogen

DataR

esou

rcefor

anno

tatio

ncomparativ

egenom

icsw

ithan

emph

asison

thefoo

d-bo

rnep

atho

gens

Yesyes

httpwwwnm

pdro

rgFIG

wikiv

iewcgi

MetaP

athw

ays

Apipelin

efor

taxono

micandfunctio

nal

anno

tatio

nfro

menvironm

entalsequence

inform

ation

Yesyes

httphallamm

icrobiolog

yubcca

MetaPathw

ays

ShotgunF

unctiona

lizeR

anR-packagefor

functio

nalcom

paris

onof

metagenom

es

Yesyes

httpshotgunmathchalmersse

MG-

RAST

automated

analysisplatform

form

etagenom

esbasedon

sequ

ence

data

Yesyes

httpmetagenom

icsa

nlgov

MEG

ANAcomprehensiv

etoo

lbox

forinteractiv

elyanalyzingmicrobiom

edata

Noyes

httpabin

funi-tu

ebingendesoft

waremegan6welc

ome

Metabolicanalysisandmodellingtooland

databases

CellD

esigner

Metabolicpathway

reconstructio

nandsim

ulation

Yesyes

httpwwwcelld

esignero

rg

E-zyme

Predictio

nof

ECnu

mbersfro

mchem

ical

transfo

rmationpatte

rnYesyes

httpwwwgeno

mejptoolse-zyme

Trito

nTo

olforE

nzym

eEng

ineerin

gYesyes

wwwncbrm

unicztrito

nEC

MDB

EcoliMetabolmed

atabase

Yesyes

httpecmdb

ca

MicrobesFlux

Aweb

platform

forg

enom

erecon

structio

nand

constraint-based

mod

ellin

gYesyes

httpwwwmicrobesflux

org

8 BioMed Research International

7 Codigestion of Food Waste

Due to high potential for biomethanation food waste isa reliable and promising substrate for anaerobic digestionactivity However longer duration of digestion may some-times lead to inhibition because of improper nutrient balance[105] On the other hand concentration of lipid in foodwaste is always higher than the limited concentration [84106] To restrain this inhibition many strategies have beenadopted by researchers to codigest the food waste with cattlemanure green waste or waste water sludge or with dairywaste Table 5 summarizes the codigestion of FW with otherorganic substrates for improving performance of anaerobicprocess

8 Anaerobic Reactors

To carry out biomethanation in practical manner differenttypes of reactors are required The researchers have useddifferent types of anaerobic reactors such as single stage andtwo-stage reactors semidry reactors solid state anaerobicreactors upflow anaerobic solid state reactors and hybridreactors for the execution of biomethanation process

Configuration of process is quite important for efficiencyofmethane production process For this single stage and two-stage process have been employed for biodegradable wastetreatment Forster-Carneiro et al [30] have reported thatwhen all phases of anaerobic digestion namely hydrolysisacidogenesis acetogenesis and methanogenesis take placesimultaneously in single reactor system encounters fewertechnical failures When all polymeric compounds such ascarbohydrates protein and fat are converted into CH4 H2SNH3 and CO2 in a single vessel then that is termed as singlestage reactor Also stability of single stage anaerobic digesterfor easily degradable FW is a matter of deep concern [23]

Chu et al [107] reported that two-stage anaerobic digesterhas been used to produce both hydrogen and methanein two separate reactors from food waste In this type ofsystem in the first stage acidogens and hydrogen producingmicroorganisms which are having faster growth rate areenriched for hydrogen production and volatile fatty acid Inthe second stage acetogens and methanogens are built upwhere volatile fatty acids are converted into methane andcarbon dioxide

It has been reported that two-stage anaerobic digestionis providing more efficient operation as compared to singlestage Park and Li [65] have reported that highest methanerecovery from kitchen waste when operated in both singlestage and two-stage system was obtained as 90 (based onCOD) which was determined at the OLR of 15 g CODLdIt was also reported by Massanet-Nicolau et al [108] thatmethane yield from food waste increased by 37 in two-stage methane fermentation process The highest methaneyields from FWs were reported by Koike et al [109] Biogasproduction of 850 LgVS during the two-stage hydrogen andmethane production processing of FWwas obtained by them

On the other hand solid state anaerobic digestion hasseveral advantages over liquid anaerobic digestion in terms ofsmaller volume required for reactors low material handling

lowwater requirement and so forth It has been reported thatfood waste is generally treated by liquid anaerobic digestionand organic fraction of municipal solid waste as well aslignocellulosic biomass can be treated by solid state anaerobicdigestion [76]

Hybrid reactors also have been proposed by someresearchers In a study performed by Hai-Lou et al [110]food waste was digested at 35∘C for 16 days in a hybridreactorThe result showed treatment efficiencies of 77ndash80 oftotal organic content removal 59-60 volatile solid removaland 79-80 total COD reduction were achieved Also highmethane content (68ndash70) from the methanogenic phasefavors the application of hybrid anaerobic solid liquid biore-actor to practical solid waste management

9 Mathematical Modelling ofAnaerobic Digestion

Based on the total operating solid content anaerobic diges-tion can be categorized as liquid state anaerobic digestion (L-AD) (TS le 15) or solid state anaerobic digestion (SS-AD)(TSge 15) [111] L-AD is adopted to treat liquid organic wastesuch as sewage sludge animal manure and waste water fromfood processing unit while SS-AD is adopted to treat solidorganic material such as yard trimmings crop residues andorganic fraction of municipal solid waste and food waste [112113] As compared to L-AD SS-AD is having advantages ofsolid loading capacity more volumetric biogas productivityand less need of energy [114]

Besides having economic and environmental benefits andbeing a promising technology a major disadvantage of solidstate anaerobic digestion is the low rate of reaction [115 116]Slow release of soluble substrate for microbial metabolismcould be the possible reason for this Till date SS-AD systemsare operated empirically and still lacking inmechanistic toolsfor controlling the process [117] Application of mathematicalmodel can be applied to anaerobic digestion for mechanismexplanation and its engineering process and parametersaffecting biomethanation and their interaction with eachother [34 118] Many researchers have adopted mathemat-ical modelling for optimizing anaerobic digestion activitybased on theoretical empirical and statistical approach Ina theoretical approach six models were adopted namelytwo-particle model [119] reaction front [120 121] distributedmodel [122ndash126] spatial temporalmodel [127 128] modifiedADM 1 [129ndash131] and diffusion limitation [132] Empiricalapproach leads to logistic modelling [133] and general kineticmodelling [134 135] Also statistical approaches such aslinear regression and artificial neural network have beenadopted [136ndash140]

Statistically derived models may emphasize prediction ofsystem behaviour and are especially useful when there are alimited number of targeting outputs while the models areblack boxmodels andmight not provide enough informationto unveil system mechanisms

On the other hand theoretical models provide moreinsight into the complex system mechanisms while simpli-fication is required to find general applications [34 141]

BioMed Research International 9

Table 5 Codigestion of food waste with other organic substrates

Feedstock Action of codigestion Influencing factor Ref

FW + CM Improve methane yield and systemstability

High buffering capacity and traceelements supplement [29]

FW + livestock waste Improve methane yield and VS reduction Higher buffering capacity [35]FW + yard waste Improve methane yield Less VFA accumulation [36]FW + dewatered sludge Enhance system stability Less inhibition from Na+ [28]FW + sewage sludge Afford high organic loading rate High buffering capacity from ammonia [37]FW + green waste Improve VS reduction CN ratio [38]FW + brown water Improve methane yield High buffering capacity [39]

FW + press water Improved system stability and methaneyield High buffering capacity [40]

FW + distillerrsquos grain Improved biogas production High buffering capacity from ammonia [41]

10 Microbial Community Analysis

Anaerobic digestion is the outcome of complex microbiomeworking in solidarity A guild of microorganisms work ondifferent phases of anaerobic digestion (Figure 4) maintain-ing a synergistic balance to ensure the stability of anaerobicdigestion However anaerobic digesters often suffer withvarious instabilities pertaining to inhibition foaming andacidification especially at high organic load rates (OLRs)[142] These instabilities are generally associated with thecharacteristics and dynamics of the microbial communitiesinvolved in anaerobic digestion process Therefore micro-bial community analysis investigating the composition andbehaviour of microbial communities can be helpful tooptimize stable and efficient process operation The high-throughput sequencing technologies have further opened upnew avenues for investigations of microbial communitiesduring anaerobic digestion Methods for revealing microbialcommunity compositions are based on the generation of16S rRNA gene clone libraries and 16S rRNA ampliconsArchaeal community are identified by targeting mcrA geneThe sequence reads are then analyzed by sophisticated bioin-formatics tools for taxonomic distribution and functionalannotations

Lim and Wang [104] studied microbial community forsingle phase and two-phase anaerobic digestion of food wasteand found predominance of Firmicutes and greater bacterialdiversity in two-phase continuous stirred tank reactor that ledto 23 higher methane yield in comparison to single phaseanaerobic digestion Methanosaeta dominated the archaealcommunity of both single phase and two-phase reactors[143] Cho et al [144] investigated methanogenic communityduring dry anaerobic digestion of food waste and observeda significant reduction in methanogen diversity after accli-mation to dry AD Almost all sequences obtained from dryanaerobic digester sludge belonged toMethanosarcina genusreported to be more tolerant to sudden change in pH anduse both acetoclastic and hydrogenotrophic pathways whichmake them more suitable for surviving in comparison toMethanosaeta Gou et al [58] investigated effect of temper-ature and organic loading rate on microbial community offood waste anaerobic digestion and found significant effect of

temperature on the richness of microbial community whichwas more diverse at 35∘C in comparison to 45∘ and 55∘CAt 55∘C only 5 species remain abundant that explains thatthermophilic bacteria aremore sensitive towards temperaturevariation

Wan et al [145] classified the nucleotide sequences byusing the ribosomal database project classifier software andshowed that Proteobacteria Firmicutes and Bacteroideteswere the most abundant microorganisms during the entireprocess of anaerobic digestion The diversity of microorgan-isms significantly increased during active methanogenesis incomparison to day 0 with addition of Synergistetes Tener-icutes Spirochaetes and Actinobacteria Li et al [142 146]introduced disturbance in OLR into mesophilic anaerobicdigester and carried out microbial community analysis dur-ing stable and deteriorative phases by employing pyrose-quencing Microbial communities were investigated using454 pyrosequencing Raw sequences were quality checked bymothur software and aligned with SILVA alignment In hisstudy the acidogenic bacteria and syntrophic VFA oxidizerswere found abundantly in deteriorative phase suggesting thatduring high OLR hydrolysis and acidogenesis surpassedthe rate of methanogenesis which led to the irreversibleacidification of accumulated VFAs

Zamanzadeh et al [147] investigated the effect of diges-tate recirculation on microbial community by using Illu-mina sequencing Taxonomic assignment of sequences wasdone by using QIIMErsquos uclust-based taxonomy assignerProteobacteria Firmicutes Chloroflexi and Bacteroideteswere found to be the dominant bacterial phyla in bothdigester configuration types (with and without recircula-tion) Methanosaeta and Methanobacterium were dominantgenera among archaeal population accounting for 65 and32 of Euryarchaeotarsquos reads in mesophilic digester withoutrecirculation while in digester with digestate recirculationMethanosaeta accounted for 91 of all EuryarchaeotarsquosTheseresults show the prevalence of acetoclastic methanogens overhydrogenotrophic methanogens which acknowledge acetatereduction as the main pathway of methane formation Simi-larly Gulhane et al [148] studied the microbial communityunder effect of no digestate recirculation 25 digestaterecirculation and 100 digestate recirculation Illumina

10 BioMed Research International

Hydro producing

Homo acetogenic

Hydrolytic bacteria (I)

Methanogenic bacteria (IV)

Acetic acid

Complex organic compound

Organic acidneutral compound

bacteria (III)

CH4CO2

one-carbon compound

H2CO2

acetogenic bacteria (II)

Figure 4 Significance of the microbial population in anaerobic digester

sequenced reads were pair assembled using PANDAseq andmothur software was used to align and filter and trim andremove chimeras and classify and assign taxonomyThe resultrevealed the domination of hydrolytic and fermentative phylain digester with no digestate recirculation while syntrophicacetogenic bacteria dominated the digester with recircula-tion

Guo et al [149] carried out comparative analysis ofthe microbial community response to increasing OLR inmesophilic and thermophilic reactor and reported thatmesophilic reactor had greater richness of microorganismsin comparison to thermophilic reactor They also reportedthe dominance of Methanosaeta in archaeal community inmesophilic reactor while presence of MethanothermobacterandMethanoculleus were favored in thermophilic reactor

11 Metagenomic Tool and Techniques forAdvance Practices

In a fast-growing world food wastage and its managementare one of the major challenges faced by our society due toinherited high risk for human health and increasing environ-mental burdens Strategic use of biodegradation processingon food waste can turn out into multiple societal benefitsProduction of energy that is biogas through biomass offood waste could be of major interest for easy storage andtransport Secondly it reduces the hazardous effects on envi-ronment through themultiple layered foodwastes processingand management Production of soil additives and liquidfertilizers from organic food waste will be direct incentivefrom food waste management Various 16S and 18S rRNA-based fragmented studieswere performed through researcherfor wastemanagement treatment andmicrobial communitieswere identified from all the three taxonomic units of themicrobial world that is Archaea Bacteria and Eukarya Intotal 4133methanogenic bacteriawere classified intoArchaeadomain and Crenarchaeota and Euryarchaeota are most

visible group [33] Methanogens have huge morphologicaldiversity cocci (Methanococcus) Spirillaceae (Methanospir-illum) Sarcina (Methanosarcina) rods (Methanobacterium)short rods (Methanobrevibacter) and filiforms (Methanoth-rix) [150] Acetotrophic methanogens are the main oblig-atory anaerobes belonging to genus Methanosarcina whichare involved in the processing of acetate to methane andcarbondioxideMethanobacteriaceae family have been foundassociated with hydrogen binding methanogenic bacteriaMethanosphaera stadtmaniae andMethanobrevibacter woliniiare the two main groups of hydrogenotrophic microor-ganisms participating in anaerobic processing of fruit andvegetable [151]

The knowledge of the link between taxonomical andfunctional diversity and species richness can be a key forbetter understanding of ecosystem functioning in waste foodtreatment Molecular methods like PCR RFLP microarraysand sequencing have been utilized in the field of wastemanagement But these methods have own limitations forlarge scale functional characterization of ecological systemsRecently capturedmetagenomics demonstrated the potentialof functional characterization of microbial communities ofagricultural soil on a large scale through NGS Applicationof these approaches for food waste management can improveour understanding about treatment and enhance qualityof treatment and management products [152] Microbialcommunities can be used in more efficient manner infood waste management through exploration of availablemicrobial resources and strategic use of available advancemetagenomics practices

111 Microarrays Microarray is a one of the easiest andpowerful tools to characterize differences in gene con-tent between organisms and gene expression Microar-ray technique has become popular due to large scalesequencing of microbial genomes year after year Hun-dreds of microbial microarray based studies have been

BioMed Research International 11

Table6Bioinformaticstoo

lsanddatabasesu

sedform

icrobialcommun

ityanalysis

Database

Featured

escriptio

nWebopensource

Availability

Microbialgenom

eand

metagenom

icdata

resource

IMG

Integrated

MicrobialGenom

esandMicrobiom

eRe

positoryof

33116geno

med

atasetsa

nd4615

microbiom

edataset

Yesyes

httpsim

gjgid

oegov

MGD

BMicrobialgeno

med

atabasew

ith4742

geno

mes

Yesyes

httpmbgdgeno

mea

djp

ENSE

MBL

Accessto

over

40000

BacterialG

enom

esYesyes

httpbacteriaen

semblorgin

dexhtml

RefSeq

(microbial)

Archaealand

bacterialreposito

ryatNCB

IRe

ferenceS

equence

Yesyes

httpsw

wwncbinlm

nihgovrefseq

Microarraysa

ndgene

expressio

ndatabase

(M3D

)ManyMicrobe

Microarrays

Database

Yesyes

httpm3dm

ssmed

uB120583

GSbase

Microarraydatasetsform

icrobialgene

expressio

nYesyes

httpbu

gssg

ulac

ukbu

gsbaseta

bsexp

erim

entp

hp

COLO

MBO

SCollectionof

bacterialgenee

xpression

compend

ium

Yesyes

httpwwwcolombo

snet

Microbeon

line

Repo

sitoryof

3707

geno

mesgenee

xpressiondata

for113

organism

sYesyes

httpwwwmicrobesonlineo

rg

Taxonomic

Functio

nalA

nnotationandCo

mparativeG

enom

ics

POGO

Databaseo

fPairw

ise-C

omparis

onsO

fGenom

esandOrtho

logous

genes

Yesyes

httppo

goec

edrexeledu

abo

utphp

MicroScope

MicrobialGenom

eAnn

otationampAnalysis

Platform

Yesyes

httpsw

wwgeno

scop

ecnsfragcm

icroscop

eho

me

AGeS

ASoftw

areS

ystem

forM

icrobialGenom

eSequ

ence

Ann

otation

Yesyes

httpwwwbh

saiorgagesh

tml

NMPD

RNationalM

icrobialPathogen

DataR

esou

rcefor

anno

tatio

ncomparativ

egenom

icsw

ithan

emph

asison

thefoo

d-bo

rnep

atho

gens

Yesyes

httpwwwnm

pdro

rgFIG

wikiv

iewcgi

MetaP

athw

ays

Apipelin

efor

taxono

micandfunctio

nal

anno

tatio

nfro

menvironm

entalsequence

inform

ation

Yesyes

httphallamm

icrobiolog

yubcca

MetaPathw

ays

ShotgunF

unctiona

lizeR

anR-packagefor

functio

nalcom

paris

onof

metagenom

es

Yesyes

httpshotgunmathchalmersse

MG-

RAST

automated

analysisplatform

form

etagenom

esbasedon

sequ

ence

data

Yesyes

httpmetagenom

icsa

nlgov

MEG

ANAcomprehensiv

etoo

lbox

forinteractiv

elyanalyzingmicrobiom

edata

Noyes

httpabin

funi-tu

ebingendesoft

waremegan6welc

ome

Metabolicanalysisandmodellingtooland

databases

CellD

esigner

Metabolicpathway

reconstructio

nandsim

ulation

Yesyes

httpwwwcelld

esignero

rg

E-zyme

Predictio

nof

ECnu

mbersfro

mchem

ical

transfo

rmationpatte

rnYesyes

httpwwwgeno

mejptoolse-zyme

Trito

nTo

olforE

nzym

eEng

ineerin

gYesyes

wwwncbrm

unicztrito

nEC

MDB

EcoliMetabolmed

atabase

Yesyes

httpecmdb

ca

MicrobesFlux

Aweb

platform

forg

enom

erecon

structio

nand

constraint-based

mod

ellin

gYesyes

httpwwwmicrobesflux

org

BioMed Research International 9

Table 5 Codigestion of food waste with other organic substrates

Feedstock Action of codigestion Influencing factor Ref

FW + CM Improve methane yield and systemstability

High buffering capacity and traceelements supplement [29]

FW + livestock waste Improve methane yield and VS reduction Higher buffering capacity [35]FW + yard waste Improve methane yield Less VFA accumulation [36]FW + dewatered sludge Enhance system stability Less inhibition from Na+ [28]FW + sewage sludge Afford high organic loading rate High buffering capacity from ammonia [37]FW + green waste Improve VS reduction CN ratio [38]FW + brown water Improve methane yield High buffering capacity [39]

FW + press water Improved system stability and methaneyield High buffering capacity [40]

FW + distillerrsquos grain Improved biogas production High buffering capacity from ammonia [41]

10 Microbial Community Analysis

Anaerobic digestion is the outcome of complex microbiomeworking in solidarity A guild of microorganisms work ondifferent phases of anaerobic digestion (Figure 4) maintain-ing a synergistic balance to ensure the stability of anaerobicdigestion However anaerobic digesters often suffer withvarious instabilities pertaining to inhibition foaming andacidification especially at high organic load rates (OLRs)[142] These instabilities are generally associated with thecharacteristics and dynamics of the microbial communitiesinvolved in anaerobic digestion process Therefore micro-bial community analysis investigating the composition andbehaviour of microbial communities can be helpful tooptimize stable and efficient process operation The high-throughput sequencing technologies have further opened upnew avenues for investigations of microbial communitiesduring anaerobic digestion Methods for revealing microbialcommunity compositions are based on the generation of16S rRNA gene clone libraries and 16S rRNA ampliconsArchaeal community are identified by targeting mcrA geneThe sequence reads are then analyzed by sophisticated bioin-formatics tools for taxonomic distribution and functionalannotations

Lim and Wang [104] studied microbial community forsingle phase and two-phase anaerobic digestion of food wasteand found predominance of Firmicutes and greater bacterialdiversity in two-phase continuous stirred tank reactor that ledto 23 higher methane yield in comparison to single phaseanaerobic digestion Methanosaeta dominated the archaealcommunity of both single phase and two-phase reactors[143] Cho et al [144] investigated methanogenic communityduring dry anaerobic digestion of food waste and observeda significant reduction in methanogen diversity after accli-mation to dry AD Almost all sequences obtained from dryanaerobic digester sludge belonged toMethanosarcina genusreported to be more tolerant to sudden change in pH anduse both acetoclastic and hydrogenotrophic pathways whichmake them more suitable for surviving in comparison toMethanosaeta Gou et al [58] investigated effect of temper-ature and organic loading rate on microbial community offood waste anaerobic digestion and found significant effect of

temperature on the richness of microbial community whichwas more diverse at 35∘C in comparison to 45∘ and 55∘CAt 55∘C only 5 species remain abundant that explains thatthermophilic bacteria aremore sensitive towards temperaturevariation

Wan et al [145] classified the nucleotide sequences byusing the ribosomal database project classifier software andshowed that Proteobacteria Firmicutes and Bacteroideteswere the most abundant microorganisms during the entireprocess of anaerobic digestion The diversity of microorgan-isms significantly increased during active methanogenesis incomparison to day 0 with addition of Synergistetes Tener-icutes Spirochaetes and Actinobacteria Li et al [142 146]introduced disturbance in OLR into mesophilic anaerobicdigester and carried out microbial community analysis dur-ing stable and deteriorative phases by employing pyrose-quencing Microbial communities were investigated using454 pyrosequencing Raw sequences were quality checked bymothur software and aligned with SILVA alignment In hisstudy the acidogenic bacteria and syntrophic VFA oxidizerswere found abundantly in deteriorative phase suggesting thatduring high OLR hydrolysis and acidogenesis surpassedthe rate of methanogenesis which led to the irreversibleacidification of accumulated VFAs

Zamanzadeh et al [147] investigated the effect of diges-tate recirculation on microbial community by using Illu-mina sequencing Taxonomic assignment of sequences wasdone by using QIIMErsquos uclust-based taxonomy assignerProteobacteria Firmicutes Chloroflexi and Bacteroideteswere found to be the dominant bacterial phyla in bothdigester configuration types (with and without recircula-tion) Methanosaeta and Methanobacterium were dominantgenera among archaeal population accounting for 65 and32 of Euryarchaeotarsquos reads in mesophilic digester withoutrecirculation while in digester with digestate recirculationMethanosaeta accounted for 91 of all EuryarchaeotarsquosTheseresults show the prevalence of acetoclastic methanogens overhydrogenotrophic methanogens which acknowledge acetatereduction as the main pathway of methane formation Simi-larly Gulhane et al [148] studied the microbial communityunder effect of no digestate recirculation 25 digestaterecirculation and 100 digestate recirculation Illumina

10 BioMed Research International

Hydro producing

Homo acetogenic

Hydrolytic bacteria (I)

Methanogenic bacteria (IV)

Acetic acid

Complex organic compound

Organic acidneutral compound

bacteria (III)

CH4CO2

one-carbon compound

H2CO2

acetogenic bacteria (II)

Figure 4 Significance of the microbial population in anaerobic digester

sequenced reads were pair assembled using PANDAseq andmothur software was used to align and filter and trim andremove chimeras and classify and assign taxonomyThe resultrevealed the domination of hydrolytic and fermentative phylain digester with no digestate recirculation while syntrophicacetogenic bacteria dominated the digester with recircula-tion

Guo et al [149] carried out comparative analysis ofthe microbial community response to increasing OLR inmesophilic and thermophilic reactor and reported thatmesophilic reactor had greater richness of microorganismsin comparison to thermophilic reactor They also reportedthe dominance of Methanosaeta in archaeal community inmesophilic reactor while presence of MethanothermobacterandMethanoculleus were favored in thermophilic reactor

11 Metagenomic Tool and Techniques forAdvance Practices

In a fast-growing world food wastage and its managementare one of the major challenges faced by our society due toinherited high risk for human health and increasing environ-mental burdens Strategic use of biodegradation processingon food waste can turn out into multiple societal benefitsProduction of energy that is biogas through biomass offood waste could be of major interest for easy storage andtransport Secondly it reduces the hazardous effects on envi-ronment through themultiple layered foodwastes processingand management Production of soil additives and liquidfertilizers from organic food waste will be direct incentivefrom food waste management Various 16S and 18S rRNA-based fragmented studieswere performed through researcherfor wastemanagement treatment andmicrobial communitieswere identified from all the three taxonomic units of themicrobial world that is Archaea Bacteria and Eukarya Intotal 4133methanogenic bacteriawere classified intoArchaeadomain and Crenarchaeota and Euryarchaeota are most

visible group [33] Methanogens have huge morphologicaldiversity cocci (Methanococcus) Spirillaceae (Methanospir-illum) Sarcina (Methanosarcina) rods (Methanobacterium)short rods (Methanobrevibacter) and filiforms (Methanoth-rix) [150] Acetotrophic methanogens are the main oblig-atory anaerobes belonging to genus Methanosarcina whichare involved in the processing of acetate to methane andcarbondioxideMethanobacteriaceae family have been foundassociated with hydrogen binding methanogenic bacteriaMethanosphaera stadtmaniae andMethanobrevibacter woliniiare the two main groups of hydrogenotrophic microor-ganisms participating in anaerobic processing of fruit andvegetable [151]

The knowledge of the link between taxonomical andfunctional diversity and species richness can be a key forbetter understanding of ecosystem functioning in waste foodtreatment Molecular methods like PCR RFLP microarraysand sequencing have been utilized in the field of wastemanagement But these methods have own limitations forlarge scale functional characterization of ecological systemsRecently capturedmetagenomics demonstrated the potentialof functional characterization of microbial communities ofagricultural soil on a large scale through NGS Applicationof these approaches for food waste management can improveour understanding about treatment and enhance qualityof treatment and management products [152] Microbialcommunities can be used in more efficient manner infood waste management through exploration of availablemicrobial resources and strategic use of available advancemetagenomics practices

111 Microarrays Microarray is a one of the easiest andpowerful tools to characterize differences in gene con-tent between organisms and gene expression Microar-ray technique has become popular due to large scalesequencing of microbial genomes year after year Hun-dreds of microbial microarray based studies have been

BioMed Research International 11

Table6Bioinformaticstoo

lsanddatabasesu

sedform

icrobialcommun

ityanalysis

Database

Featured

escriptio

nWebopensource

Availability

Microbialgenom

eand

metagenom

icdata

resource

IMG

Integrated

MicrobialGenom

esandMicrobiom

eRe

positoryof

33116geno

med

atasetsa

nd4615

microbiom

edataset

Yesyes

httpsim

gjgid

oegov

MGD

BMicrobialgeno

med

atabasew

ith4742

geno

mes

Yesyes

httpmbgdgeno

mea

djp

ENSE

MBL

Accessto

over

40000

BacterialG

enom

esYesyes

httpbacteriaen

semblorgin

dexhtml

RefSeq

(microbial)

Archaealand

bacterialreposito

ryatNCB

IRe

ferenceS

equence

Yesyes

httpsw

wwncbinlm

nihgovrefseq

Microarraysa

ndgene

expressio

ndatabase

(M3D

)ManyMicrobe

Microarrays

Database

Yesyes

httpm3dm

ssmed

uB120583

GSbase

Microarraydatasetsform

icrobialgene

expressio

nYesyes

httpbu

gssg

ulac

ukbu

gsbaseta

bsexp

erim

entp

hp

COLO

MBO

SCollectionof

bacterialgenee

xpression

compend

ium

Yesyes

httpwwwcolombo

snet

Microbeon

line

Repo

sitoryof

3707

geno

mesgenee

xpressiondata

for113

organism

sYesyes

httpwwwmicrobesonlineo

rg

Taxonomic

Functio

nalA

nnotationandCo

mparativeG

enom

ics

POGO

Databaseo

fPairw

ise-C

omparis

onsO

fGenom

esandOrtho

logous

genes

Yesyes

httppo

goec

edrexeledu

abo

utphp

MicroScope

MicrobialGenom

eAnn

otationampAnalysis

Platform

Yesyes

httpsw

wwgeno

scop

ecnsfragcm

icroscop

eho

me

AGeS

ASoftw

areS

ystem

forM

icrobialGenom

eSequ

ence

Ann

otation

Yesyes

httpwwwbh

saiorgagesh

tml

NMPD

RNationalM

icrobialPathogen

DataR

esou

rcefor

anno

tatio

ncomparativ

egenom

icsw

ithan

emph

asison

thefoo

d-bo

rnep

atho

gens

Yesyes

httpwwwnm

pdro

rgFIG

wikiv

iewcgi

MetaP

athw

ays

Apipelin

efor

taxono

micandfunctio

nal

anno

tatio

nfro

menvironm

entalsequence

inform

ation

Yesyes

httphallamm

icrobiolog

yubcca

MetaPathw

ays

ShotgunF

unctiona

lizeR

anR-packagefor

functio

nalcom

paris

onof

metagenom

es

Yesyes

httpshotgunmathchalmersse

MG-

RAST

automated

analysisplatform

form

etagenom

esbasedon

sequ

ence

data

Yesyes

httpmetagenom

icsa

nlgov

MEG

ANAcomprehensiv

etoo

lbox

forinteractiv

elyanalyzingmicrobiom

edata

Noyes

httpabin

funi-tu

ebingendesoft

waremegan6welc

ome

Metabolicanalysisandmodellingtooland

databases

CellD

esigner

Metabolicpathway

reconstructio

nandsim

ulation

Yesyes

httpwwwcelld

esignero

rg

E-zyme

Predictio

nof

ECnu

mbersfro

mchem

ical

transfo

rmationpatte

rnYesyes

httpwwwgeno

mejptoolse-zyme

Trito

nTo

olforE

nzym

eEng

ineerin

gYesyes

wwwncbrm

unicztrito

nEC

MDB

EcoliMetabolmed

atabase

Yesyes

httpecmdb

ca

MicrobesFlux

Aweb

platform

forg

enom

erecon

structio

nand

constraint-based

mod

ellin

gYesyes

httpwwwmicrobesflux

org

10 BioMed Research International

Hydro producing

Homo acetogenic

Hydrolytic bacteria (I)

Methanogenic bacteria (IV)

Acetic acid

Complex organic compound

Organic acidneutral compound

bacteria (III)

CH4CO2

one-carbon compound

H2CO2

acetogenic bacteria (II)

Figure 4 Significance of the microbial population in anaerobic digester

sequenced reads were pair assembled using PANDAseq andmothur software was used to align and filter and trim andremove chimeras and classify and assign taxonomyThe resultrevealed the domination of hydrolytic and fermentative phylain digester with no digestate recirculation while syntrophicacetogenic bacteria dominated the digester with recircula-tion

Guo et al [149] carried out comparative analysis ofthe microbial community response to increasing OLR inmesophilic and thermophilic reactor and reported thatmesophilic reactor had greater richness of microorganismsin comparison to thermophilic reactor They also reportedthe dominance of Methanosaeta in archaeal community inmesophilic reactor while presence of MethanothermobacterandMethanoculleus were favored in thermophilic reactor

11 Metagenomic Tool and Techniques forAdvance Practices

In a fast-growing world food wastage and its managementare one of the major challenges faced by our society due toinherited high risk for human health and increasing environ-mental burdens Strategic use of biodegradation processingon food waste can turn out into multiple societal benefitsProduction of energy that is biogas through biomass offood waste could be of major interest for easy storage andtransport Secondly it reduces the hazardous effects on envi-ronment through themultiple layered foodwastes processingand management Production of soil additives and liquidfertilizers from organic food waste will be direct incentivefrom food waste management Various 16S and 18S rRNA-based fragmented studieswere performed through researcherfor wastemanagement treatment andmicrobial communitieswere identified from all the three taxonomic units of themicrobial world that is Archaea Bacteria and Eukarya Intotal 4133methanogenic bacteriawere classified intoArchaeadomain and Crenarchaeota and Euryarchaeota are most

visible group [33] Methanogens have huge morphologicaldiversity cocci (Methanococcus) Spirillaceae (Methanospir-illum) Sarcina (Methanosarcina) rods (Methanobacterium)short rods (Methanobrevibacter) and filiforms (Methanoth-rix) [150] Acetotrophic methanogens are the main oblig-atory anaerobes belonging to genus Methanosarcina whichare involved in the processing of acetate to methane andcarbondioxideMethanobacteriaceae family have been foundassociated with hydrogen binding methanogenic bacteriaMethanosphaera stadtmaniae andMethanobrevibacter woliniiare the two main groups of hydrogenotrophic microor-ganisms participating in anaerobic processing of fruit andvegetable [151]

The knowledge of the link between taxonomical andfunctional diversity and species richness can be a key forbetter understanding of ecosystem functioning in waste foodtreatment Molecular methods like PCR RFLP microarraysand sequencing have been utilized in the field of wastemanagement But these methods have own limitations forlarge scale functional characterization of ecological systemsRecently capturedmetagenomics demonstrated the potentialof functional characterization of microbial communities ofagricultural soil on a large scale through NGS Applicationof these approaches for food waste management can improveour understanding about treatment and enhance qualityof treatment and management products [152] Microbialcommunities can be used in more efficient manner infood waste management through exploration of availablemicrobial resources and strategic use of available advancemetagenomics practices

111 Microarrays Microarray is a one of the easiest andpowerful tools to characterize differences in gene con-tent between organisms and gene expression Microar-ray technique has become popular due to large scalesequencing of microbial genomes year after year Hun-dreds of microbial microarray based studies have been

BioMed Research International 11

Table6Bioinformaticstoo

lsanddatabasesu

sedform

icrobialcommun

ityanalysis

Database

Featured

escriptio

nWebopensource

Availability

Microbialgenom

eand

metagenom

icdata

resource

IMG

Integrated

MicrobialGenom

esandMicrobiom

eRe

positoryof

33116geno

med

atasetsa

nd4615

microbiom

edataset

Yesyes

httpsim

gjgid

oegov

MGD

BMicrobialgeno

med

atabasew

ith4742

geno

mes

Yesyes

httpmbgdgeno

mea

djp

ENSE

MBL

Accessto

over

40000

BacterialG

enom

esYesyes

httpbacteriaen

semblorgin

dexhtml

RefSeq

(microbial)

Archaealand

bacterialreposito

ryatNCB

IRe

ferenceS

equence

Yesyes

httpsw

wwncbinlm

nihgovrefseq

Microarraysa

ndgene

expressio

ndatabase

(M3D

)ManyMicrobe

Microarrays

Database

Yesyes

httpm3dm

ssmed

uB120583

GSbase

Microarraydatasetsform

icrobialgene

expressio

nYesyes

httpbu

gssg

ulac

ukbu

gsbaseta

bsexp

erim

entp

hp

COLO

MBO

SCollectionof

bacterialgenee

xpression

compend

ium

Yesyes

httpwwwcolombo

snet

Microbeon

line

Repo

sitoryof

3707

geno

mesgenee

xpressiondata

for113

organism

sYesyes

httpwwwmicrobesonlineo

rg

Taxonomic

Functio

nalA

nnotationandCo

mparativeG

enom

ics

POGO

Databaseo

fPairw

ise-C

omparis

onsO

fGenom

esandOrtho

logous

genes

Yesyes

httppo

goec

edrexeledu

abo

utphp

MicroScope

MicrobialGenom

eAnn

otationampAnalysis

Platform

Yesyes

httpsw

wwgeno

scop

ecnsfragcm

icroscop

eho

me

AGeS

ASoftw

areS

ystem

forM

icrobialGenom

eSequ

ence

Ann

otation

Yesyes

httpwwwbh

saiorgagesh

tml

NMPD

RNationalM

icrobialPathogen

DataR

esou

rcefor

anno

tatio

ncomparativ

egenom

icsw

ithan

emph

asison

thefoo

d-bo

rnep

atho

gens

Yesyes

httpwwwnm

pdro

rgFIG

wikiv

iewcgi

MetaP

athw

ays

Apipelin

efor

taxono

micandfunctio

nal

anno

tatio

nfro

menvironm

entalsequence

inform

ation

Yesyes

httphallamm

icrobiolog

yubcca

MetaPathw

ays

ShotgunF

unctiona

lizeR

anR-packagefor

functio

nalcom

paris

onof

metagenom

es

Yesyes

httpshotgunmathchalmersse

MG-

RAST

automated

analysisplatform

form

etagenom

esbasedon

sequ

ence

data

Yesyes

httpmetagenom

icsa

nlgov

MEG

ANAcomprehensiv

etoo

lbox

forinteractiv

elyanalyzingmicrobiom

edata

Noyes

httpabin

funi-tu

ebingendesoft

waremegan6welc

ome

Metabolicanalysisandmodellingtooland

databases

CellD

esigner

Metabolicpathway

reconstructio

nandsim

ulation

Yesyes

httpwwwcelld

esignero

rg

E-zyme

Predictio

nof

ECnu

mbersfro

mchem

ical

transfo

rmationpatte

rnYesyes

httpwwwgeno

mejptoolse-zyme

Trito

nTo

olforE

nzym

eEng

ineerin

gYesyes

wwwncbrm

unicztrito

nEC

MDB

EcoliMetabolmed

atabase

Yesyes

httpecmdb

ca

MicrobesFlux

Aweb

platform

forg

enom

erecon

structio

nand

constraint-based

mod

ellin

gYesyes

httpwwwmicrobesflux

org

BioMed Research International 11

Table6Bioinformaticstoo

lsanddatabasesu

sedform

icrobialcommun

ityanalysis

Database

Featured

escriptio

nWebopensource

Availability

Microbialgenom

eand

metagenom

icdata

resource

IMG

Integrated

MicrobialGenom

esandMicrobiom

eRe

positoryof

33116geno

med

atasetsa

nd4615

microbiom

edataset

Yesyes

httpsim

gjgid

oegov

MGD

BMicrobialgeno

med

atabasew

ith4742

geno

mes

Yesyes

httpmbgdgeno

mea

djp

ENSE

MBL

Accessto

over

40000

BacterialG

enom

esYesyes

httpbacteriaen

semblorgin

dexhtml

RefSeq

(microbial)

Archaealand

bacterialreposito

ryatNCB

IRe

ferenceS

equence

Yesyes

httpsw

wwncbinlm

nihgovrefseq

Microarraysa

ndgene

expressio

ndatabase

(M3D

)ManyMicrobe

Microarrays

Database

Yesyes

httpm3dm

ssmed

uB120583

GSbase

Microarraydatasetsform

icrobialgene

expressio

nYesyes

httpbu

gssg

ulac

ukbu

gsbaseta

bsexp

erim

entp

hp

COLO

MBO

SCollectionof

bacterialgenee

xpression

compend

ium

Yesyes

httpwwwcolombo

snet

Microbeon

line

Repo

sitoryof

3707

geno

mesgenee

xpressiondata

for113

organism

sYesyes

httpwwwmicrobesonlineo

rg

Taxonomic

Functio

nalA

nnotationandCo

mparativeG

enom

ics

POGO

Databaseo

fPairw

ise-C

omparis

onsO

fGenom

esandOrtho

logous

genes

Yesyes

httppo

goec

edrexeledu

abo

utphp

MicroScope

MicrobialGenom

eAnn

otationampAnalysis

Platform

Yesyes

httpsw

wwgeno

scop

ecnsfragcm

icroscop

eho

me

AGeS

ASoftw

areS

ystem

forM

icrobialGenom

eSequ

ence

Ann

otation

Yesyes

httpwwwbh

saiorgagesh

tml

NMPD

RNationalM

icrobialPathogen

DataR

esou

rcefor

anno

tatio

ncomparativ

egenom

icsw

ithan

emph

asison

thefoo

d-bo

rnep

atho

gens

Yesyes

httpwwwnm

pdro

rgFIG

wikiv

iewcgi

MetaP

athw

ays

Apipelin

efor

taxono

micandfunctio

nal

anno

tatio

nfro

menvironm

entalsequence

inform

ation

Yesyes

httphallamm

icrobiolog

yubcca

MetaPathw

ays

ShotgunF

unctiona

lizeR

anR-packagefor

functio

nalcom

paris

onof

metagenom

es

Yesyes

httpshotgunmathchalmersse

MG-

RAST

automated

analysisplatform

form

etagenom

esbasedon

sequ

ence

data

Yesyes

httpmetagenom

icsa

nlgov

MEG

ANAcomprehensiv

etoo

lbox

forinteractiv

elyanalyzingmicrobiom

edata

Noyes

httpabin

funi-tu

ebingendesoft

waremegan6welc

ome

Metabolicanalysisandmodellingtooland

databases

CellD

esigner

Metabolicpathway

reconstructio

nandsim

ulation

Yesyes

httpwwwcelld

esignero

rg

E-zyme

Predictio

nof

ECnu

mbersfro

mchem

ical

transfo

rmationpatte

rnYesyes

httpwwwgeno

mejptoolse-zyme

Trito

nTo

olforE

nzym

eEng

ineerin

gYesyes

wwwncbrm

unicztrito

nEC

MDB

EcoliMetabolmed

atabase

Yesyes

httpecmdb

ca

MicrobesFlux

Aweb

platform

forg

enom

erecon

structio

nand

constraint-based

mod

ellin

gYesyes

httpwwwmicrobesflux

org

12 BioMed Research International

Table6Con

tinued

Database

Featured

escriptio

nWebopensource

Availability

MetaC

ycMetaC

ycMetabolicPathway

Database

Yesyes

httpmetacycorg

MetaB

ioMe

Datam

iningengine

fork

nownCom

mercially

UsefulE

nzym

es(C

UEs)inmetagenom

icdatasets

andgeno

mes

Yesyes

httpmetasystemsrikenjpm

etabiome

Metabolom

eSearcher

HTS

toolform

etabolite

identifi

catio

nand

metabolicpathway

mapping

directlyfro

mmass

spectro

metry

andmetabolites

httpprocycwestcentu

sued

ucgi-b

inM

etaboSearchercgi

ProC

yc

Anop

enresource

forthe

study

ofmetabolic

capabilitiesinmicroorganism

sfrom

food

environm

entandspecificp

atho

gens

from

these

sources

Yesyes

httpprocycwestcentu

sued

u1555

MEM

OSys

Bioinformaticsp

latfo

rmforg

enom

e-scale

metabolicmod

elsYesyes

httpicbiatsoft

waremem

osysm

emosyssh

tml

EAWAG

-BBD

Microbialbiocatalyticreactio

nsand

biod

egradatio

npathways

Yesyes

httpeawag-bbd

ethzch

Desharky

Microbialbiod

egradatio

nto

hostmetabolites

httpsoftsynth-bioorgdesharkyhtm

lPathPred

Microbialbiod

egradatio

nYesyes

httpwwwgeno

mejptools-binpathpredpathp

redcgi

CRAFT

Chem

icalRe

activ

ityandFatetool

Biod

egradatio

nof

aerobicb

acteria

httpsw

wwmn-am

comprodu

ctscraft

EAWAG

-BBD

PPS

BPT

Biod

egradatio

ninform

ationof

aerobicanaerobic

bacteria

Yesyes

httpeawag-bbd

ethzch

MetaboleExp

ert

Biod

egradatio

nby

plantsandanim

als

httpwwwcompu

drugco

mm

etabolexpert

Mod

elSE

EDMicrobialandplantm

etabolicmod

ellin

gYesyes

httpmod

elseedorg

COBR

AToo

lBox

Con

straint-based

mod

ellin

gMAT

LABand

Python

Yesyes

httpop

encobrag

ithub

iocob

ratoolbo

x

OptFlux

Toolform

etabolicengineering

Yesyes

httpwwwop

tflux

org

BioMed Research International 13

published such as 16S rRNA-based taxonomic microar-ray for Proteobacteria [153] and Alphaproteobacteria [154]Actinomycetes microarray [155] Bacillus-PhyloChip [156]Burkholderia-PhyloChip [157] ECC-PhyloChip [158] Com-post Community-Microarray [159] Freshwater Sediment-Microarray [160] Soilmicrobial community PhyloChip [161]SRP-PhyloChip [162] and Nitrifier-Microarray [163] Recentadvancement in sequencing and molecular technologieshas opened the doors for metagenomic studies Capturedmetagenomics is one example for high resolution study forsoil metagenomes [152 164]

112 Next-Generation Sequencing The high-throughputnext-generation sequencing (HT-NGS) technologies producea lot more data compared to capillary sequencing basedmethod Sequencing technology revolution started withRoche 454 GS FLX+ and currently it can produce relativelylong read length (approx 700 bp) and low number of reads(approx 1 million readsrun) and is used for different appli-cations such as examining 16S variable regions targetedamplicon sequences microbial genomes BACs and plastidsIllumina is one of the biggest players in the sequencingmarket with their versatile range of instruments and is idealfor genome sequencing and resequencing transcriptomesequencing SNP detection and metagenomic studies Illu-mina read length (50ndash300 bp) and readnumber (25Millionndash6billion per run) vary fromplatform to platform [165] IonTor-rent technology (Ion PGM and Ion proton) is relatively newand semiconductor based sequencing platform Potential ofthe platform varies with respect to the semiconductor chipthat is used that is Ion 314 Chip v2 Ion 316 Chip v2 andIon 318Chip v2 (read length 200ndash400 bp readsrun 500Kndash5 million) It is used for various sequencing applicationssuch as amplicons small genomes and targeted genomicsequencing Automated workflow from sample preparationto analysis makes it ideal for smaller sized studies and routinepractices [166] PacBio RS have been developed for longread lengths through single molecule real-time sequencingtechnology which can generate reads from 1 kb up to 60KbEach SMRT cell can generate approx 50000 reads Longerread length feature makes it ideal for sequencing smallgenomes such as bacteria or viruses regions of high GCcontent and DNAwith modified bases (methylation hydrox-ymethylation) resequencing projects and so forth [167]

113 Bioinformatics Resources In 1970 Paulien Hogeweg andBen Hesper coined the term ldquobioinformaticsrdquo for the studyof information processes in biological systems as techniqueCurrently bioinformatics is enormously integrated in almostall biological fields The success of bioinformatics is mainlydue to the recent advancements in computational resourcesand infrastructure across the globe which has facilitatedbioinformatics research on complex biological systems [168]

Molecular insight in the diversity of the microbialcommunities is a relatively young field as not much wasknown about it prior to 1975 due to the unavailability ofadvance methods tool and techniques [169] The advance-ment of sequencing and computational technology promoted

metagenomics researches which increased the bioinformat-ics outreach in microbial informatics and experimentationFurther development of the bioinformatics methods resultedin a large number of databases tools and data formatsfor the analysis of microorganism and microbiome relatedstudies which enhanced our knowledge and understandingof microbial populations [170] In recent years the advance-ment of high-throughput next-generation sequencing (NGS)platforms has enabled large scale sequencing efforts forthe exploration of microbial ecosystems Consequently themicrobial ecological analysis in the near future will need aparadigm shift fromdata generation to datamanagement andsharing and hypothesis driven and targeted data generation[171] in silico generated knowledge coding mining and net-working to improve our encoded models for new knowledgediscovery [172 173] Here (Table 6) we have reviewed majormicrobial databases and tools that can be useful for microbialresearch application in emerging applied fields like foodwastemanagement and applications

12 Conclusions

Proper disposal of foodwaste has posed a stern pecuniary andenvironmental concern It appears that conversion of foodwaste into energy via anaerobic processes in terms ofmethaneis economically viable However difficulties accompanyingthe collection as well as transportation of food waste shouldalso be considered Nevertheless the stumpy or no cost offoodwaste alongwith the environmental aids considering thewaste discarding would balance the initial high investmentcosts of the biorefineries Moreover the efficacy and costbase of the generation could be upgraded by intensifyingresearch and optimization studies on assimilating differentvalue-added product manufacturing processes

Competing Interests

The authors declare that they have no conflict of interests

Acknowledgments

The authors would like to thank Department of Biotechnol-ogy and Department of Sciences and Technology Govern-ment of India

References

[1] FAO Towards the Future we Want End Hunger and Make theTransition to Sustainable Agricultural and Food Systems Foodand Agriculture Organization of the United Nations Rome2012

[2] MMelikoglu C S K Lin and CWebb ldquoAnalysing global foodwaste problem pinpointing the facts and estimating the energycontentrdquo Central European Journal of Engineering vol 3 no 2pp 157ndash164 2013

[3] A Agarwal A Singhmar M Kulshrestha and A K MittalldquoMunicipal solid waste recycling and associated markets inDelhi Indiardquo Resources Conservation and Recycling vol 44 no1 pp 73ndash90 2005

14 BioMed Research International

[4] K N Kumar and S Goel ldquoCharacterization of Municipal SolidWaste (MSW) and a proposedmanagement plan for KharagpurWest Bengal Indiardquo Resources Conservation and Recycling vol53 no 3 pp 166ndash174 2009

[5] S Kumar J K Bhattacharyya A N Vaidya T ChakrabartiS Devotta and A B Akolkar ldquoAssessment of the statusof municipal solid waste management in metro cities statecapitals class I cities and class II towns in India an insightrdquoWaste Management vol 29 no 2 pp 883ndash895 2009

[6] S Pattnaik and M V Reddy ldquoAssessment of municipalsolid waste management in Puducherry (Pondicherry) IndiardquoResources Conservation and Recycling vol 54 no 8 pp 512ndash520 2010

[7] V Talyan R P Dahiya and T R Sreekrishnan ldquoState ofmunicipal solid waste management in Delhi the capital ofIndiardquoWaste Management vol 28 no 7 pp 1276ndash1287 2008

[8] T Katami A Yasuhara and T Shibamoto ldquoFormation ofdioxins from incineration of foods found in domestic garbagerdquoEnvironmental Science and Technology vol 38 no 4 pp 1062ndash1065 2004

[9] H Ma Q Wang D Qian L Gong and W Zhang ldquoTheutilization of acid-tolerant bacteria on ethanol production fromkitchen garbagerdquo Renewable Energy vol 34 no 6 pp 1466ndash1470 2009

[10] T N B Dung B Sen C C Chen G Kumar and C YLin ldquoFood waste to bioenergy via anaerobic processesrdquo EnergyProcedia vol 61 pp 307ndash312 2014

[11] FAO FAOSTAT World Food and Agriculture Statistical Year-book FAO-Food amp Agriculture Organization of the UnitedNation Rome Italy 2013

[12] I M Nasir T I M Ghazi and R Omar ldquoProduction ofbiogas from solid organic wastes through anaerobic digestion areviewrdquo Applied Microbiology and Biotechnology vol 95 no 2pp 321ndash329 2012

[13] M Morita and K Sasaki ldquoFactors influencing the degradationof garbage in methanogenic bioreactors and impacts on biogasformationrdquoAppliedMicrobiology and Biotechnology vol 94 no3 pp 575ndash582 2012

[14] Y Ohkouchi and Y Inoue ldquoDirect production of l(+)-lacticacid from starch and food wastes using Lactobacillus maniho-tivorans LMG18011rdquo Bioresource Technology vol 97 no 13 pp1554ndash1562 2006

[15] Y-Q Tang Y Koike K Liu et al ldquoEthanol production fromkitchen waste using the flocculating yeast Saccharomyces cere-visiae strain KF-7rdquo Biomass and Bioenergy vol 32 no 11 pp1037ndash1045 2008

[16] Q Wang H Ma W Xu L Gong W Zhang and D ZouldquoEthanol production from kitchen garbage using responsesurface methodologyrdquo Biochemical Engineering Journal vol 39no 3 pp 604ndash610 2008

[17] B Zhang Z-G He L-L Zhang J-B Xu H-Z Shi andW-MCai ldquoAnaerobic digestion of kitchen wastes in a single-phasedanaerobic sequencing batch reactor (ASBR) with gas-phasedabsorb of CO2rdquo Journal of Environmental Sciences vol 17 no2 pp 249ndash255 2005

[18] H Ma Q Wang W Zhang W Xu and D Zou ldquoOptimizationof the medium and process parameters for ethanol productionfrom kitchen garbage by Zymomonas mobilisrdquo InternationalJournal of Green Energy vol 5 no 6 pp 480ndash490 2008

[19] O N Uncu and D Cekmecelioglu ldquoCost-effective approachto ethanol production and optimization by response surface

methodologyrdquo Waste Management vol 31 no 4 pp 636ndash6432011

[20] M He Y Sun D Zou et al ldquoInfluence of temperature onhydrolysis acidification of food wasterdquo Procedia EnvironmentalSciences vol 16 pp 85ndash94 2012

[21] A I Vavouraki E M Angelis andM Kornaros ldquoOptimizationof thermo-chemical hydrolysis of kitchen wastesrdquo Waste Man-agement vol 33 no 3 pp 740ndash745 2013

[22] L Zhang and D Jahng ldquoLong-term anaerobic digestion of foodwaste stabilized by trace elementsrdquoWaste Management vol 32no 8 pp 1509ndash1515 2012

[23] J P Lee J S Lee and S C Park ldquoTwo-phase methanization offood wastes in pilot scalerdquoApplied Biochemistry and Biotechnol-ogy vol 77ndash79 pp 585ndash593 1999

[24] V N Gunaseelan ldquoBiochemical methane potential of fruits andvegetable solid waste feedstocksrdquo Biomass and Bioenergy vol26 no 4 pp 389ndash399 2004

[25] J-H Youn and H-S Shin ldquoComparative performance betweentemperature-phased and conventional mesophilic two-phasedprocesses in terms of anaerobically produced bioenergy fromfood wasterdquoWaste Management and Research vol 23 no 1 pp32ndash38 2005

[26] C J BanksM Chesshire S Heaven and R Arnold ldquoAnaerobicdigestion of source-segregated domestic food waste perfor-mance assessment by mass and energy balancerdquo BioresourceTechnology vol 102 no 2 pp 612ndash620 2011

[27] H C Moon and I S Song ldquoEnzymatic hydrolysis of foodwasteand methane production using UASB bioreactorrdquo InternationalJournal of Green Energy vol 8 no 3 pp 361ndash371 2011

[28] X Dai N Duan B Dong and L Dai ldquoHigh-solids anaerobicco-digestion of sewage sludge and food waste in comparisonwith mono digestions stability and performancerdquo Waste Man-agement vol 33 no 2 pp 308ndash316 2013

[29] C Zhang G Xiao L Peng H Su and T Tan ldquoThe anaerobicco-digestion of food waste and cattle manurerdquo BioresourceTechnology vol 129 pp 170ndash176 2013

[30] T Forster-Carneiro M Perez and L I Romero ldquoInfluence oftotal solid and inoculum contents on performance of anaerobicreactors treating foodwasterdquoBioresource Technology vol 99 no15 pp 6994ndash7002 2008

[31] D-H Kim S-H Kim K-Y Kim and H-S Shin ldquoExperi-ence of a pilot-scale hydrogen-producing anaerobic sequencingbatch reactor (ASBR) treating foodwasterdquo International Journalof Hydrogen Energy vol 35 no 4 pp 1590ndash1594 2010

[32] J K Kim G H Han B R Oh Y N Chun C-Y Eom and SWKim ldquoVolumetric scale-up of a three stage fermentation systemfor food waste treatmentrdquo Bioresource Technology vol 99 no10 pp 4394ndash4399 2008

[33] K Zieminski and M Frąc ldquoMethane fermentation process asanaerobic digestion of biomass transformations stages andmicroorganismsrdquo African Journal of Biotechnology vol 11 no18 pp 4127ndash4139 2012

[34] J Lauwers L Appels I PThompson J Degreve J F Van Impeand R Dewil ldquoMathematical modelling of anaerobic digestionof biomass andwaste power and limitationsrdquo Progress in Energyand Combustion Science vol 39 no 4 pp 383ndash402 2013

[35] D-H Kim and S-E Oh ldquoContinuous high-solids anaerobic co-digestion of organic solid wastes under mesophilic conditionsrdquoWaste Management vol 31 no 9-10 pp 1943ndash1948 2011

[36] D Brown and Y Li ldquoSolid state anaerobic co-digestion ofyard waste and food waste for biogas productionrdquo BioresourceTechnology vol 127 pp 275ndash280 2013

BioMed Research International 15

[37] H-W Kim J-Y Nam and H-S Shin ldquoA comparison studyon the high-rate co-digestion of sewage sludge and food wasteusing a temperature-phased anaerobic sequencing batch reactorsystemrdquo Bioresource Technology vol 102 no 15 pp 7272ndash72792011

[38] M Kumar Y-L Ou and J-G Lin ldquoCo-composting of greenwaste and food waste at low CN ratiordquoWasteManagement vol30 no 4 pp 602ndash609 2010

[39] R Rajagopal J W Lim Y Mao C-L Chen and J-Y WangldquoAnaerobic co-digestion of source segregated brown water(feces-without-urine) and food waste for Singapore contextrdquoScience of the Total Environment vol 443 pp 877ndash886 2013

[40] S E Nayono C Gallert and J Winter ldquoCo-digestion of presswater and food waste in a biowaste digester for improvement ofbiogas productionrdquo Bioresource Technology vol 101 no 18 pp6987ndash6993 2010

[41] L-H Wang Q Wang W Cai and X Sun ldquoInfluence ofmixing proportion on the solid-state anaerobic co-digestion ofdistillerrsquos grains and food wasterdquo Biosystems Engineering vol112 no 2 pp 130ndash137 2012

[42] K M Mittal Biogas Systems Policies Progress and ProspectsNew Age International New Delhi India 1997

[43] M P Bryant ldquoMicrobial methane production theoreticalaspectsrdquo Journal of Animal Science vol 48 no 1 pp 193ndash2011979

[44] B Schink ldquoEnergetics of syntrophic cooperation in metha-nogenic degradationrdquo Microbiology and Molecular BiologyReviews vol 61 no 2 pp 262ndash280 1997

[45] M E Griffin K D McMahon R I Mackie and L RaskinldquoMethanogenic population dynamics during start-up of anaer-obic digesters treating municipal solid waste and biosolidsrdquoBiotechnology and Bioengineering vol 57 no 3 pp 342ndash3551998

[46] D Karakashev D J Batstone and I Angelidaki ldquoInfluence ofenvironmental conditions on methanogenic compositions inanaerobic biogas reactorsrdquo Applied and Environmental Micro-biology vol 71 no 1 pp 331ndash338 2005

[47] AM Viturtia J Mata-Alvarez F Cecchi andG Fazzini ldquoTwo-phase anaerobic digestion of a mixture of fruit and vegetablewastesrdquo Biological Wastes vol 29 no 3 pp 189ndash199 1989

[48] J K Cho S C Park and H N Chang ldquoBiochemical methanepotential and solid state anaerobic digestion of Korean foodwastesrdquo Bioresource Technology vol 52 no 3 pp 245ndash253 1995

[49] Z Yong YDong X Zhang andT Tan ldquoAnaerobic co-digestionof food waste and straw for biogas productionrdquo RenewableEnergy vol 78 pp 527ndash530 2015

[50] N Curry and P Pillay ldquoBiogas prediction and design of a foodwaste to energy system for the urban environmentrdquo RenewableEnergy vol 41 pp 200ndash209 2012

[51] R E Anderson Biological Path to Self-Reliance Van NostrandReinhold Company New York NY USA 1979

[52] P Dhevagi K Ramasamy and G Oblisami Biological NitrogenFixation and Biogas Technology Tamilnadu Agricultural Uni-versity 1992

[53] S H Zinder ldquoPhysiological ecology of methanogensrdquo inMethanogenesis Ecology Physiology Biochemistry andGeneticsJ G Ferry Ed pp 128ndash206 Chapman and Hall New York NYUSA 1993

[54] L Arsova Anaerobic digestion of food waste current statusproblems and an alternative product [MS thesis] ColumbiaUniversity Berlin Germany 2010

[55] A C Van Haandel and G Lettinga Anaerobic SewageTreatmentmdashA Practical Guide for Regions with a Hot ClimateJohn Wiley amp Sons New York NY USA 1994

[56] H Bouallagui O Haouari Y Touhami R Ben Cheikh LMarouani and M Hamdi ldquoEffect of temperature on theperformance of an anaerobic tubular reactor treating fruit andvegetable wasterdquo Process Biochemistry vol 39 no 12 pp 2143ndash2148 2004

[57] J K Kim B R Oh Y N Chun and S W Kim ldquoEffects of tem-perature and hydraulic retention time on anaerobic digestion offood wasterdquo Journal of Bioscience and Bioengineering vol 102no 4 pp 328ndash332 2006

[58] C Gou Z Yang J Huang H Wang H Xu and L WangldquoEffects of temperature and organic loading rate on the perfor-mance and microbial community of anaerobic co-digestion ofwaste activated sludge and food wasterdquo Chemosphere vol 105pp 146ndash151 2014

[59] X Wang G Yang Y Feng G Ren and X Han ldquoOptimizingfeeding composition and carbon-nitrogen ratios for improvedmethane yield during anaerobic co-digestion of dairy chickenmanure and wheat strawrdquo Bioresource Technology vol 120 pp78ndash83 2012

[60] D H Lee S K Behera J W Kim and H-S Park ldquoMethaneproduction potential of leachate generated from Korean foodwaste recycling facilities a lab-scale studyrdquoWaste Managementvol 29 no 2 pp 876ndash882 2009

[61] R Goel T Tokutomi and H Yasui ldquoAnaerobic digestion ofexcess activated sludge with ozone pretreatmentrdquoWater Scienceand Technology vol 47 no 12 pp 207ndash214 2003

[62] K M Mittal Biogas Systems Principles and Application NewAge International New Delhi India 1996

[63] Zeshan O P Karthikeyan and C Visvanathan ldquoEffect ofCN ratio and ammonia-N accumulation in a pilot-scale ther-mophilic dry anaerobic digesterrdquo Bioresource Technology vol113 pp 294ndash302 2012

[64] W Zhong L Chi Y Luo Z Zhang Z Zhang and W-M WuldquoEnhanced methane production from Taihu Lake blue algaeby anaerobic co-digestion with corn straw in continuous feeddigestersrdquo Bioresource Technology vol 134 pp 264ndash270 2013

[65] S Park and Y Li ldquoEvaluation of methane production andmacronutrient degradation in the anaerobic co-digestion ofalgae biomass residue and lipid wasterdquo Bioresource Technologyvol 111 pp 42ndash48 2012

[66] H-W Yen and D E Brune ldquoAnaerobic co-digestion of algalsludge and waste paper to produce methanerdquo BioresourceTechnology vol 98 no 1 pp 130ndash134 2007

[67] J Van Brakel The Ignis Fatuus of Biogas Small-Scale AnaerobicDigesters (lsquoBiogas Plantsrsquo) A Critical Review of the Premdash1970Literature Delft University Press 1980

[68] I Siegert andC Banks ldquoThe effect of volatile fatty acid additionson the anaerobic digestion of cellulose and glucose in batchreactorsrdquo Process Biochemistry vol 40 no 11 pp 3412ndash34182005

[69] K Vijayaraghavan V S Varma and S P Kamala NalinildquoHydrogen generation from biological solid waste of milkprocessing effluent treatment planrdquo International Journal ofCurrent Trends and Resources vol 1 pp 17ndash23 2012

[70] R A Labatut L T Angenent and N R Scott ldquoBiochemicalmethane potential and biodegradability of complex organicsubstratesrdquo Bioresource Technology vol 102 no 3 pp 2255ndash2264 2011

16 BioMed Research International

[71] H Bouallagui Y Touhami R Ben Cheikh and M HamdildquoBioreactor performance in anaerobic digestion of fruit andvegetable wastesrdquo Process Biochemistry vol 40 no 3-4 pp 989ndash995 2005

[72] P D Cotter and C Hill ldquoSurviving the acid test responses ofgram-positive bacteria to low pHrdquoMicrobiology and MolecularBiology Reviews vol 67 no 3 pp 429ndash453 2003

[73] B Zhang L-L Zhang S-C Zhang H-Z Shi and W-M CaildquoThe influence of pH on hydrolysis and acidogenesis of kitchenwastes in two-phase anaerobic digestionrdquo Environmental Tech-nology vol 26 no 3 pp 329ndash339 2005

[74] J A Eastman and J F Ferguson ldquoSolubilisation of particulateorganic carbon during theacid phase of ADrdquo Journal of theWater Pollution Control Federation vol 53 pp 352ndash366 1981

[75] E P Taiganides ldquoBiomass-energy recovery from animal wastePart IrdquoWorld Animal Review vol 35 p 2 1980

[76] N Nagao N Tajima M Kawai et al ldquoMaximum organicloading rate for the single-stage wet anaerobic digestion of foodwasterdquo Bioresource Technology vol 118 pp 210ndash218 2012

[77] E Tampio S Ervasti T Paavola S Heaven C Banks and JRintala ldquoAnaerobic digestion of autoclaved and untreated foodwasterdquoWaste Management vol 34 no 2 pp 370ndash377 2014

[78] F O Agyeman and W Tao ldquoAnaerobic co-digestion of foodwaste and dairy manure effects of food waste particle size andorganic loading raterdquo Journal of Environmental Managementvol 133 pp 268ndash274 2014

[79] M Carlsson A Lagerkvist and H Ecke ldquoElectroporationfor enhanced Methane yield from municipal solid wasterdquo inProceedings of the Moving Organic Waste Recycling TowardsResource Management and Biobased Economy (ORBIT rsquo08) vol6 pp 1ndash8 Wageningen the Netherlands October 2008

[80] L H Hagen V Vivekanand R Linjordet P B Pope V GH Eijsink and S J Horn ldquoMicrobial community structureand dynamics during co-digestion of whey permeate and cowmanure in continuous stirred tank reactor systemsrdquo BioresourceTechnology vol 171 pp 350ndash359 2014

[81] O Yenigun and B Demirel ldquoAmmonia inhibition in anaerobicdigestion a reviewrdquo Process Biochemistry vol 48 no 5-6 pp901ndash911 2013

[82] M J Whelan T Everitt and R Villa ldquoA mass transfer modelof ammonia volatilisation from anaerobic digestaterdquo WasteManagement vol 30 no 10 pp 1808ndash1812 2010

[83] M Walker K Iyer S Heaven and C J Banks ldquoAmmoniaremoval in anaerobic digestion by biogas stripping an evalu-ation of process alternatives using a first order rate model basedon experimental findingsrdquo Chemical Engineering Journal vol178 pp 138ndash145 2011

[84] C Zhang H Su and T Tan ldquoBatch and semi-continuousanaerobic digestion of foodwaste in a dual solidndashliquid systemrdquoBioresource Technology vol 145 pp 10ndash16 2013

[85] F Raposo V Fernandez-Cegrı M A de la Rubia et al ldquoBio-chemical methane potential (BMP) of solid organic substratesevaluation of anaerobic biodegradability using data from aninternational interlaboratory studyrdquo Journal of Chemical Tech-nology and Biotechnology vol 86 no 8 pp 1088ndash1098 2011

[86] P Jin S K Bhattacharya C J Williams and H Zhang ldquoEffectsof sulfide addition on copper inhibition in methanogenicsystemsrdquoWater Research vol 32 no 4 pp 977ndash988 1998

[87] A Schattauer E Abdoun P Weiland M Plochl and MHeiermann ldquoAbundance of trace elements in demonstrationbiogas plantsrdquo Biosystems Engineering vol 108 no 1 pp 57ndash652011

[88] V Facchin C Cavinato F Fatone P Pavan F Cecchi andD Bolzonella ldquoEffect of trace element supplementation on themesophilic anaerobic digestion of foodwaste in batch trials theinfluence of inoculum originrdquo Biochemical Engineering Journalvol 70 pp 71ndash77 2013

[89] C A Jackson-Moss J R Duncan and D R Cooper ldquoThe effectof calciumon anaerobic digestionrdquoBiotechnology Letters vol 11no 3 pp 219ndash224 1989

[90] H Q Yu J H Tay and H H P Fang ldquoThe roles of calciumin sludge granulation during UASB reactor start-uprdquo WaterResearch vol 35 no 4 pp 1052ndash1060 2001

[91] C-Y Lin and C-C Chen ldquoEffect of heavy metals on themethanogenic UASB granulerdquoWater Research vol 33 no 2 pp409ndash416 1999

[92] G Zayed and JWinter ldquoInhibition ofmethane production fromwhey by heavy metalsmdashprotective effect of sulfiderdquo AppliedMicrobiology andBiotechnology vol 53 no 6 pp 726ndash731 2000

[93] S Ghosh M P Henry and R W Christopher ldquoHemicelluloseconversion by anaerobic digestionrdquo Biomass vol 6 no 4 pp257ndash269 1985

[94] E Elbeshbishy G Nakhla andHHafez ldquoBiochemicalmethanepotential (BMP) of food waste and primary sludge influenceof inoculum pre-incubation and inoculum sourcerdquo BioresourceTechnology vol 110 pp 18ndash25 2012

[95] M S Lisboa and S Lansing ldquoCharacterizing food waste sub-strates for co-digestion through biochemical methane potential(BMP) experimentsrdquo Waste Management vol 33 no 12 pp2664ndash2669 2013

[96] M Murto L Bjornsson H Rosqvist and I Bohn ldquoEvaluatingthe biogas potential of the dry fraction from pretreatment offood waste from householdsrdquoWaste Management vol 33 no 5pp 1282ndash1289 2013

[97] J Marin K J Kennedy and C Eskicioglu ldquoEffect of microwaveirradiation on anaerobic degradability of model kitchen wasterdquoWaste Management vol 30 no 10 pp 1772ndash1779 2010

[98] K Izumi Y K Okishio C Niwa S Yamamoto and T TodaldquoEffects of particle size on anaerobic digestion of food wasterdquoInternational Journal of Bio-Deterioration Biodegradation vol64 no 7 pp 601ndash608 2010

[99] J Ma T H Duong M Smits W Verstraete and M CarballaldquoEnhanced biomethanation of kitchen waste by different pre-treatmentsrdquo Bioresource Technology vol 102 no 2 pp 592ndash5992011

[100] J-Y Wang X-Y Liu J C M Kao and O Stabnikova ldquoDiges-tion of pre-treated food waste in a hybrid anaerobic solid-liquid (HASL) systemrdquo Journal of Chemical Technology andBiotechnology vol 81 no 3 pp 345ndash351 2006

[101] O Stabnikova X Y Liu and J Y Wang ldquoDigestion offrozenthawed food waste in the hybrid anaerobic solid-liquidsystemrdquoWaste Management vol 28 no 9 pp 1654ndash1659 2008

[102] X Liu W Wang X Gao Y Zhou and R Shen ldquoEffect ofthermal pretreatment on the physical and chemical propertiesof municipal biomass wasterdquoWaste Management vol 32 no 2pp 249ndash255 2012

[103] SWKim J Y Park J K Kim et al ldquoDevelopment of amodifiedthree-stage methane production process using food wastesrdquoApplied Biochemistry and Biotechnology vol 84ndash86 pp 731ndash7412000

[104] J W Lim and J-Y Wang ldquoEnhanced hydrolysis and methaneyield by applying microaeration pretreatment to the anaerobicco-digestion of brown water and food wasterdquo Waste Manage-ment vol 33 no 4 pp 813ndash819 2013

BioMed Research International 17

[105] L Neves R Oliveira and M M Alves ldquoCo-digestion of cowmanure food waste and intermittent input of fatrdquo BioresourceTechnology vol 100 no 6 pp 1957ndash1962 2009

[106] S G Kim ldquoSystem for separation of oil and sludge from foodwaste leachaterdquo Korea Patent 10-2010-0053719

[107] C-F Chu Y-Y Li K-Q Xu Y Ebie Y Inamori and H-NKong ldquoA pH- and temperature-phased two-stage process forhydrogen and methane production from food wasterdquo Interna-tional Journal of Hydrogen Energy vol 33 no 18 pp 4739ndash47462008

[108] JMassanet-Nicolau R Dinsdale A Guwy andG Shipley ldquoUseof real time gas production data for more accurate comparisonof continuous single-stage and two-stage fermentationrdquo Biore-source Technology vol 129 pp 561ndash567 2013

[109] Y Koike M-Z An Y-Q Tang et al ldquoProduction of fuelethanol andmethane from garbage by high-efficiency two-stagefermentation processrdquo Journal of Bioscience and Bioengineeringvol 108 no 6 pp 508ndash512 2009

[110] X Hai-LouW Jing-Yuan and T Joo-Hwa ldquoA hybrid anaerobicsolid-liquid bioreactor for food waste digestionrdquo BiotechnologyLetters vol 24 no 10 pp 757ndash761 2002

[111] Y Li S Y Park and J Zhu ldquoSolid-state anaerobic digestionfor methane production from organic wasterdquo Renewable andSustainable Energy Reviews vol 15 no 1 pp 821ndash826 2011

[112] L Appels J Baeyens J Degreve and R Dewil ldquoPrinciples andpotential of the anaerobic digestion of waste-activated sludgerdquoProgress in Energy and Combustion Science vol 34 no 6 pp755ndash781 2008

[113] O P Karthikeyan and C Visvanathan ldquoBio-energy recoveryfrom high-solid organic substrates by dry anaerobic bio-conversion processes a reviewrdquo Reviews in EnvironmentalScience and BioTechnology vol 12 no 3 pp 257ndash284 2013

[114] J Guendouz P Buffiere J CachoMCarrere and J-PDelgenesldquoDry anaerobic digestion in batch mode design and operationof a laboratory-scale completelymixed reactorrdquoWasteManage-ment vol 30 no 10 pp 1768ndash1771 2010

[115] L Yang F Xu X Ge and Y Li ldquoChallenges and strategiesfor solid-state anaerobic digestion of lignocellulosic biomassrdquoRenewable and Sustainable Energy Reviews vol 44 pp 824ndash8342015

[116] A Abbassi-Guendouz E Trably J Hamelin et al ldquoMicro-bial community signature of high-solid content methanogenicecosystemsrdquo Bioresource Technology vol 133 pp 256ndash262 2013

[117] J Lindmark E Thorin R Bel Fdhila and E Dahlquis ldquoProb-lems and possibilities with the implementation of simulationand modeling at a biogas plantrdquo in Proceedings of the Interna-tional Conference on Applied Energy (ICAE rsquo12) Suzhou ChinaJuly 2012

[118] I Angelidaki L Ellegaard and B K Ahring ldquoA mathematicalmodel for dynamic simulation of anaerobic digestion of com-plex substrates focusing on ammonia inhibitionrdquoBiotechnologyand Bioengineering vol 42 no 2 pp 159ndash166 1993

[119] S Kalyuzhnyi A Veeken and B Hamelers ldquoTwo-particlemodel of anaerobic solid state fermentationrdquoWater Science andTechnology vol 41 no 3 pp 43ndash50 2000

[120] D J Martin L G A Potts and V A Heslop ldquoReactionmechanisms in solid-state anaerobic digestion I The reactionfront hypothesisrdquo Process Safety and Environmental Protectionvol 81 no 3 pp 171ndash179 2003

[121] D J Martin ldquoA novel mathematical model of solid-statedigestionrdquo Biotechnology Letters vol 22 no 1 pp 91ndash94 2000

[122] V A Vavilin M Y Shchelkanov and S V Rytov ldquoEffect of masstransfer on concentration wave propagation during anaerobicdigestion of solidwasterdquoWater Research vol 36 no 9 pp 2405ndash2409 2002

[123] V A Vavilin L Y Lokshina J P Y Jokela and J A RintalaldquoModeling solid waste decompositionrdquo Bioresource Technologyvol 94 no 1 pp 69ndash81 2004

[124] V A Vavilin S V Rytov L Y Lokshina S G Pavlostathisand M A Barlaz ldquoDistributed model of solid waste anaerobicdigestion effects of leachate recirculation and pH adjustmentrdquoBiotechnology and Bioengineering vol 81 no 1 pp 66ndash73 2003

[125] V A Vavilin and I Angelidaki ldquoAnaerobic degradation of solidmaterial importance of initiation centers for methanogenesismixing intensity and 2D distributed modelrdquo Biotechnology andBioengineering vol 89 no 1 pp 113ndash122 2005

[126] V A Vavilin L Y Lokshina X Flotats and I AngelidakildquoAnaerobic digestion of solid material multidimensional mod-eling of continuous-flow reactor with non-uniform influentconcentration distributionsrdquo Biotechnology and Bioengineeringvol 97 no 2 pp 354ndash366 2007

[127] H J Eber ldquoSimulation of chemical reaction fronts in anaerobicdigestion of solid wasterdquo in Proceedings of the ComputationalScience and Its Applications (ICCSA rsquo03) pp 503ndash512 MontrealCanada May 2003

[128] H J Eberl ldquoThe role of spatio-temporal effects in anaerobicdigestion of solid wasterdquo Nonlinear Analysis Theory Methodsamp Applications vol 63 no 5ndash7 pp e1497ndashe1505 2005

[129] A Abbassi-Guendouz D Brockmann E Trably et al ldquoTotalsolids content drives high solid anaerobic digestion via masstransfer limitationrdquo Bioresource Technology vol 111 pp 55ndash612012

[130] J Bollon R Le-Hyaric H Benbelkacem and P BuffiereldquoDevelopment of a kinetic model for anaerobic dry digestionprocesses focus on acetate degradation and moisture contentrdquoBiochemical Engineering Journal vol 56 no 3 pp 212ndash218 2011

[131] F Liotta P Chatellier G Esposito et al ldquoModified AnaerobicDigestionModel No1 for dry and semi-dry anaerobic digestionof solid organic wasterdquo Environmental Technology vol 36 no5ndash8 pp 870ndash880 2015

[132] F Xu Z-W Wang L Tang and Y Li ldquoA mass diffusion-basedinterpretation of the effect of total solids content on solid-state anaerobic digestion of cellulosic biomassrdquo BioresourceTechnology vol 167 pp 178ndash185 2014

[133] S Pommier D Chenu M Quintard and X Lefebvre ldquoAlogistic model for the prediction of the influence of water onthe solid waste methanization in landfillsrdquo Biotechnology andBioengineering vol 97 no 3 pp 473ndash482 2007

[134] L A Fdez-Guelfo C Alvarez-Gallego D Sales and L IRomero Garcıa ldquoDry-thermophilic anaerobic digestion oforganic fraction of municipal solid waste methane productionmodelingrdquoWasteManagement vol 32 no 3 pp 382ndash388 2012

[135] J Fernandez M Perez and L I Romero ldquoKinetics ofmesophilic anaerobic digestion of the organic fraction ofmunicipal solid waste influence of initial total solid concen-trationrdquo Bioresource Technology vol 101 no 16 pp 6322ndash63282010

[136] L N Liew J Shi and Y Li ldquoMethane production from solid-state anaerobic digestion of lignocellulosic biomassrdquo Biomassand Bioenergy vol 46 pp 125ndash132 2012

[137] D Brown J Shi and Y Li ldquoComparison of solid-state to liquidanaerobic digestion of lignocellulosic feedstocks for biogasproductionrdquo Bioresource Technology vol 124 pp 379ndash386 2012

18 BioMed Research International

[138] X Tong L H Smith and P LMcCarty ldquoMethane fermentationof selected lignocellulosic materialsrdquo Biomass vol 21 no 4 pp239ndash255 1990

[139] J-C Motte R Escudie N Bernet J-P Delgenes J-P Steyerand C Dumas ldquoDynamic effect of total solid content low sub-strateinoculum ratio and particle size on solid-state anaerobicdigestionrdquo Bioresource Technology vol 144 pp 141ndash148 2013

[140] F Xu Z-W Wang and Y Li ldquoPredicting the methane yieldof lignocellulosic biomass in mesophilic solid-state anaerobicdigestion based on feedstock characteristics and process param-etersrdquo Bioresource Technology vol 173 pp 168ndash176 2014

[141] F Xu Y Li and Z-W Wang ldquoMathematical modeling of solid-state anaerobic digestionrdquo Progress in Energy and CombustionScience vol 51 pp 49ndash66 2015

[142] L Li Q He Y Ma X Wang and X Peng ldquoDynamicsof microbial community in a mesophilic anaerobic digestertreating food waste relationship between community structureand process stabilityrdquo Bioresource Technology vol 189 pp 113ndash120 2015

[143] J W Lim C-L Chen I J R Ho and J-Y Wang ldquoStudy ofmicrobial community and biodegradation efficiency for single-and two-phase anaerobic co-digestion of brown water and foodwasterdquo Bioresource Technology vol 147 pp 193ndash201 2013

[144] S-K Cho W-T Im D-H Kim M-H Kim H-S Shin and S-E Oh ldquoDry anaerobic digestion of foodwaste undermesophilicconditions performance and methanogenic community analy-sisrdquo Bioresource Technology vol 131 pp 210ndash217 2013

[145] S Wan L Sun J Sun and W Luo ldquoBiogas production andmicrobial community change during the Co-digestion of foodwaste with chinese silver grass in a single-stage anaerobicreactorrdquo Biotechnology and Bioprocess Engineering vol 18 no5 pp 1022ndash1030 2013

[146] L Li Q He Y Ma X Wang and X Peng ldquoA mesophilicanaerobic digester for treating food waste process stability andmicrobial community analysis using pyrosequencingrdquo Micro-bial Cell Factories vol 15 no 1 article no 65 2016

[147] M Zamanzadeh L H Hagen K Svensson R Linjordet and SJ Horn ldquoAnaerobic digestion of food wastemdasheffect of recircula-tion and temperature on performance andmicrobiologyrdquoWaterResearch vol 96 pp 246ndash254 2016

[148] M Gulhane P Pandit A Khardenavis and D Singh ldquoStudyof microbial community plasticity for anaerobic digestionof vegetable waste in Anaerobic Baffled Reactorrdquo RenewableEnergy vol 96 pp 246ndash254 2016

[149] X Guo C Wang F Sun W Zhu and W Wu ldquoA comparisonof microbial characteristics between the thermophilic andmesophilic anaerobic digesters exposed to elevated food wasteloadingsrdquo Bioresource Technology vol 152 pp 420ndash428 2014

[150] F Ali Shah Q Mahmood M Maroof Shah A Pervez and SAhmadAsad ldquoMicrobial ecology of anaerobic digesters the keyplayers of anaerobiosisrdquo The Scientific World Journal vol 2014Article ID 183752 21 pages 2014

[151] H Bouallagui M Torrijos J J Godon et al ldquoMicrobial mon-itoring by molecular tools of a two-phase anaerobic bioreactortreating fruit and vegetable wastesrdquo Biotechnology Letters vol26 no 10 pp 857ndash862 2004

[152] L Manoharan S K Kushwaha K Hedlund and D AhrenldquoCaptured metagenomics large-scale targeting of genes basedon rsquosequence capturersquo reveals functional diversity in soilsrdquoDNAResearch vol 22 no 6 pp 451ndash460 2015

[153] H Sanguin B Remenant A Dechesne et al ldquoPotential ofa 16S rRNA-based taxonomic microarray for analyzing the

rhizosphere effects ofmaize onAgrobacteriumspp and bacterialcommunitiesrdquoApplied and EnvironmentalMicrobiology vol 72no 6 pp 4302ndash4312 2006

[154] H Sanguin A Herrera C Oger-Desfeux et al ldquoDevelopmentand validation of a prototype 16S rRNA-based taxonomicmicroarray for Alphaproteobacteriardquo Environmental Microbiol-ogy vol 8 no 2 pp 289ndash307 2006

[155] M Kyselkova J Kopecky T Felfoldi et al ldquoDevelopment of a16S rRNA gene-based prototype microarray for the detection ofselected actinomycetes generardquo International Journal of Generaland Molecular Microbiology vol 94 no 3 pp 439ndash453 2008

[156] W-T Liu A D Mirzabekov and D A Stahl ldquoOptimization ofan oligonucleotide microchip for microbial identification stud-ies a non-equilibrium dissociation approachrdquo EnvironmentalMicrobiology vol 3 no 10 pp 619ndash629 2001

[157] S Schonmann A Loy C Wimmersberger et al ldquo16S rRNAgene-based phylogenetic microarray for simultaneous identifi-cation of members of the genus Burkholderiardquo EnvironmentalMicrobiology vol 11 no 4 pp 779ndash800 2009

[158] A E Warsen M J Krug S LaFrentz D R Stanek F JLoge and D R Call ldquoSimultaneous discrimination between15 fish pathogens by using 16S ribosomal DNA PCR and DNAmicroarraysrdquo Applied and Environmental Microbiology vol 70no 7 pp 4216ndash4221 2004

[159] I H Franke-Whittle S H Klammer and H Insam ldquoDesignand application of an oligonucleotide microarray for theinvestigation of compost microbial communitiesrdquo Journal ofMicrobiological Methods vol 62 no 1 pp 37ndash56 2005

[160] J Peplies C Lachmund F O Glockner and W Manz ldquoADNA microarray platform based on direct detection of rRNAfor characterization of freshwater sediment-related prokaryoticcommunitiesrdquoApplied and EnvironmentalMicrobiology vol 72no 7 pp 4829ndash4838 2006

[161] S Demaneche H Sanguin J Pote et al ldquoAntibiotic-resistantsoil bacteria in transgenic plant fieldsrdquo Proceedings of theNational Academy of Sciences of the United States of Americavol 105 no 10 pp 3957ndash3962 2008

[162] A Loy A Lehner N Lee et al ldquoOligonucleotide microarrayfor 16S rRNA gene-based detection of all recognized lineagesof sulfate-reducing prokaryotes in the environmentrdquo Appliedand Environmental Microbiology vol 68 no 10 pp 5064ndash50812002

[163] S Siripong J J Kelly D A Stahl and B E Rittmann ldquoImpactof prehybridization PCR amplification onmicroarray detectionof nitrifying bacteria in wastewater treatment plant samplesrdquoEnvironmental Microbiology vol 8 no 9 pp 1564ndash1574 2006

[164] S K Kushwaha L Manoharan T Meerupati K Hedlundand D Ahren ldquoErratum to MetCap a bioinformatics probedesign pipeline for large-scale targeted metagenomicsrdquo BMCBioinformatics vol 17 article 39 2016

[165] httpswwwilluminacomtechnologynext-generation-sequen-cingsequencing-technologyhtml

[166] httpswwwthermofishercominenhomelife-sciencesequen-cingnext-generation-sequencingion-torrent-next-generation-sequencing-workflowion-torrent-next-generation-sequencing-run-sequenceion-proton-system-for-next-generation-sequen-cinghtml

[167] httpwwwpacbcomproducts-and-servicespacbio-systemsrsii

[168] F J Azuaje M Heymann A-M Ternes et al ldquoBioinformaticsas a driver not a passenger of translational biomedical research

14 BioMed Research International

[4] K N Kumar and S Goel ldquoCharacterization of Municipal SolidWaste (MSW) and a proposedmanagement plan for KharagpurWest Bengal Indiardquo Resources Conservation and Recycling vol53 no 3 pp 166ndash174 2009

[5] S Kumar J K Bhattacharyya A N Vaidya T ChakrabartiS Devotta and A B Akolkar ldquoAssessment of the statusof municipal solid waste management in metro cities statecapitals class I cities and class II towns in India an insightrdquoWaste Management vol 29 no 2 pp 883ndash895 2009

[6] S Pattnaik and M V Reddy ldquoAssessment of municipalsolid waste management in Puducherry (Pondicherry) IndiardquoResources Conservation and Recycling vol 54 no 8 pp 512ndash520 2010

[7] V Talyan R P Dahiya and T R Sreekrishnan ldquoState ofmunicipal solid waste management in Delhi the capital ofIndiardquoWaste Management vol 28 no 7 pp 1276ndash1287 2008

[8] T Katami A Yasuhara and T Shibamoto ldquoFormation ofdioxins from incineration of foods found in domestic garbagerdquoEnvironmental Science and Technology vol 38 no 4 pp 1062ndash1065 2004

[9] H Ma Q Wang D Qian L Gong and W Zhang ldquoTheutilization of acid-tolerant bacteria on ethanol production fromkitchen garbagerdquo Renewable Energy vol 34 no 6 pp 1466ndash1470 2009

[10] T N B Dung B Sen C C Chen G Kumar and C YLin ldquoFood waste to bioenergy via anaerobic processesrdquo EnergyProcedia vol 61 pp 307ndash312 2014

[11] FAO FAOSTAT World Food and Agriculture Statistical Year-book FAO-Food amp Agriculture Organization of the UnitedNation Rome Italy 2013

[12] I M Nasir T I M Ghazi and R Omar ldquoProduction ofbiogas from solid organic wastes through anaerobic digestion areviewrdquo Applied Microbiology and Biotechnology vol 95 no 2pp 321ndash329 2012

[13] M Morita and K Sasaki ldquoFactors influencing the degradationof garbage in methanogenic bioreactors and impacts on biogasformationrdquoAppliedMicrobiology and Biotechnology vol 94 no3 pp 575ndash582 2012

[14] Y Ohkouchi and Y Inoue ldquoDirect production of l(+)-lacticacid from starch and food wastes using Lactobacillus maniho-tivorans LMG18011rdquo Bioresource Technology vol 97 no 13 pp1554ndash1562 2006

[15] Y-Q Tang Y Koike K Liu et al ldquoEthanol production fromkitchen waste using the flocculating yeast Saccharomyces cere-visiae strain KF-7rdquo Biomass and Bioenergy vol 32 no 11 pp1037ndash1045 2008

[16] Q Wang H Ma W Xu L Gong W Zhang and D ZouldquoEthanol production from kitchen garbage using responsesurface methodologyrdquo Biochemical Engineering Journal vol 39no 3 pp 604ndash610 2008

[17] B Zhang Z-G He L-L Zhang J-B Xu H-Z Shi andW-MCai ldquoAnaerobic digestion of kitchen wastes in a single-phasedanaerobic sequencing batch reactor (ASBR) with gas-phasedabsorb of CO2rdquo Journal of Environmental Sciences vol 17 no2 pp 249ndash255 2005

[18] H Ma Q Wang W Zhang W Xu and D Zou ldquoOptimizationof the medium and process parameters for ethanol productionfrom kitchen garbage by Zymomonas mobilisrdquo InternationalJournal of Green Energy vol 5 no 6 pp 480ndash490 2008

[19] O N Uncu and D Cekmecelioglu ldquoCost-effective approachto ethanol production and optimization by response surface

methodologyrdquo Waste Management vol 31 no 4 pp 636ndash6432011

[20] M He Y Sun D Zou et al ldquoInfluence of temperature onhydrolysis acidification of food wasterdquo Procedia EnvironmentalSciences vol 16 pp 85ndash94 2012

[21] A I Vavouraki E M Angelis andM Kornaros ldquoOptimizationof thermo-chemical hydrolysis of kitchen wastesrdquo Waste Man-agement vol 33 no 3 pp 740ndash745 2013

[22] L Zhang and D Jahng ldquoLong-term anaerobic digestion of foodwaste stabilized by trace elementsrdquoWaste Management vol 32no 8 pp 1509ndash1515 2012

[23] J P Lee J S Lee and S C Park ldquoTwo-phase methanization offood wastes in pilot scalerdquoApplied Biochemistry and Biotechnol-ogy vol 77ndash79 pp 585ndash593 1999

[24] V N Gunaseelan ldquoBiochemical methane potential of fruits andvegetable solid waste feedstocksrdquo Biomass and Bioenergy vol26 no 4 pp 389ndash399 2004

[25] J-H Youn and H-S Shin ldquoComparative performance betweentemperature-phased and conventional mesophilic two-phasedprocesses in terms of anaerobically produced bioenergy fromfood wasterdquoWaste Management and Research vol 23 no 1 pp32ndash38 2005

[26] C J BanksM Chesshire S Heaven and R Arnold ldquoAnaerobicdigestion of source-segregated domestic food waste perfor-mance assessment by mass and energy balancerdquo BioresourceTechnology vol 102 no 2 pp 612ndash620 2011

[27] H C Moon and I S Song ldquoEnzymatic hydrolysis of foodwasteand methane production using UASB bioreactorrdquo InternationalJournal of Green Energy vol 8 no 3 pp 361ndash371 2011

[28] X Dai N Duan B Dong and L Dai ldquoHigh-solids anaerobicco-digestion of sewage sludge and food waste in comparisonwith mono digestions stability and performancerdquo Waste Man-agement vol 33 no 2 pp 308ndash316 2013

[29] C Zhang G Xiao L Peng H Su and T Tan ldquoThe anaerobicco-digestion of food waste and cattle manurerdquo BioresourceTechnology vol 129 pp 170ndash176 2013

[30] T Forster-Carneiro M Perez and L I Romero ldquoInfluence oftotal solid and inoculum contents on performance of anaerobicreactors treating foodwasterdquoBioresource Technology vol 99 no15 pp 6994ndash7002 2008

[31] D-H Kim S-H Kim K-Y Kim and H-S Shin ldquoExperi-ence of a pilot-scale hydrogen-producing anaerobic sequencingbatch reactor (ASBR) treating foodwasterdquo International Journalof Hydrogen Energy vol 35 no 4 pp 1590ndash1594 2010

[32] J K Kim G H Han B R Oh Y N Chun C-Y Eom and SWKim ldquoVolumetric scale-up of a three stage fermentation systemfor food waste treatmentrdquo Bioresource Technology vol 99 no10 pp 4394ndash4399 2008

[33] K Zieminski and M Frąc ldquoMethane fermentation process asanaerobic digestion of biomass transformations stages andmicroorganismsrdquo African Journal of Biotechnology vol 11 no18 pp 4127ndash4139 2012

[34] J Lauwers L Appels I PThompson J Degreve J F Van Impeand R Dewil ldquoMathematical modelling of anaerobic digestionof biomass andwaste power and limitationsrdquo Progress in Energyand Combustion Science vol 39 no 4 pp 383ndash402 2013

[35] D-H Kim and S-E Oh ldquoContinuous high-solids anaerobic co-digestion of organic solid wastes under mesophilic conditionsrdquoWaste Management vol 31 no 9-10 pp 1943ndash1948 2011

[36] D Brown and Y Li ldquoSolid state anaerobic co-digestion ofyard waste and food waste for biogas productionrdquo BioresourceTechnology vol 127 pp 275ndash280 2013

BioMed Research International 15

[37] H-W Kim J-Y Nam and H-S Shin ldquoA comparison studyon the high-rate co-digestion of sewage sludge and food wasteusing a temperature-phased anaerobic sequencing batch reactorsystemrdquo Bioresource Technology vol 102 no 15 pp 7272ndash72792011

[38] M Kumar Y-L Ou and J-G Lin ldquoCo-composting of greenwaste and food waste at low CN ratiordquoWasteManagement vol30 no 4 pp 602ndash609 2010

[39] R Rajagopal J W Lim Y Mao C-L Chen and J-Y WangldquoAnaerobic co-digestion of source segregated brown water(feces-without-urine) and food waste for Singapore contextrdquoScience of the Total Environment vol 443 pp 877ndash886 2013

[40] S E Nayono C Gallert and J Winter ldquoCo-digestion of presswater and food waste in a biowaste digester for improvement ofbiogas productionrdquo Bioresource Technology vol 101 no 18 pp6987ndash6993 2010

[41] L-H Wang Q Wang W Cai and X Sun ldquoInfluence ofmixing proportion on the solid-state anaerobic co-digestion ofdistillerrsquos grains and food wasterdquo Biosystems Engineering vol112 no 2 pp 130ndash137 2012

[42] K M Mittal Biogas Systems Policies Progress and ProspectsNew Age International New Delhi India 1997

[43] M P Bryant ldquoMicrobial methane production theoreticalaspectsrdquo Journal of Animal Science vol 48 no 1 pp 193ndash2011979

[44] B Schink ldquoEnergetics of syntrophic cooperation in metha-nogenic degradationrdquo Microbiology and Molecular BiologyReviews vol 61 no 2 pp 262ndash280 1997

[45] M E Griffin K D McMahon R I Mackie and L RaskinldquoMethanogenic population dynamics during start-up of anaer-obic digesters treating municipal solid waste and biosolidsrdquoBiotechnology and Bioengineering vol 57 no 3 pp 342ndash3551998

[46] D Karakashev D J Batstone and I Angelidaki ldquoInfluence ofenvironmental conditions on methanogenic compositions inanaerobic biogas reactorsrdquo Applied and Environmental Micro-biology vol 71 no 1 pp 331ndash338 2005

[47] AM Viturtia J Mata-Alvarez F Cecchi andG Fazzini ldquoTwo-phase anaerobic digestion of a mixture of fruit and vegetablewastesrdquo Biological Wastes vol 29 no 3 pp 189ndash199 1989

[48] J K Cho S C Park and H N Chang ldquoBiochemical methanepotential and solid state anaerobic digestion of Korean foodwastesrdquo Bioresource Technology vol 52 no 3 pp 245ndash253 1995

[49] Z Yong YDong X Zhang andT Tan ldquoAnaerobic co-digestionof food waste and straw for biogas productionrdquo RenewableEnergy vol 78 pp 527ndash530 2015

[50] N Curry and P Pillay ldquoBiogas prediction and design of a foodwaste to energy system for the urban environmentrdquo RenewableEnergy vol 41 pp 200ndash209 2012

[51] R E Anderson Biological Path to Self-Reliance Van NostrandReinhold Company New York NY USA 1979

[52] P Dhevagi K Ramasamy and G Oblisami Biological NitrogenFixation and Biogas Technology Tamilnadu Agricultural Uni-versity 1992

[53] S H Zinder ldquoPhysiological ecology of methanogensrdquo inMethanogenesis Ecology Physiology Biochemistry andGeneticsJ G Ferry Ed pp 128ndash206 Chapman and Hall New York NYUSA 1993

[54] L Arsova Anaerobic digestion of food waste current statusproblems and an alternative product [MS thesis] ColumbiaUniversity Berlin Germany 2010

[55] A C Van Haandel and G Lettinga Anaerobic SewageTreatmentmdashA Practical Guide for Regions with a Hot ClimateJohn Wiley amp Sons New York NY USA 1994

[56] H Bouallagui O Haouari Y Touhami R Ben Cheikh LMarouani and M Hamdi ldquoEffect of temperature on theperformance of an anaerobic tubular reactor treating fruit andvegetable wasterdquo Process Biochemistry vol 39 no 12 pp 2143ndash2148 2004

[57] J K Kim B R Oh Y N Chun and S W Kim ldquoEffects of tem-perature and hydraulic retention time on anaerobic digestion offood wasterdquo Journal of Bioscience and Bioengineering vol 102no 4 pp 328ndash332 2006

[58] C Gou Z Yang J Huang H Wang H Xu and L WangldquoEffects of temperature and organic loading rate on the perfor-mance and microbial community of anaerobic co-digestion ofwaste activated sludge and food wasterdquo Chemosphere vol 105pp 146ndash151 2014

[59] X Wang G Yang Y Feng G Ren and X Han ldquoOptimizingfeeding composition and carbon-nitrogen ratios for improvedmethane yield during anaerobic co-digestion of dairy chickenmanure and wheat strawrdquo Bioresource Technology vol 120 pp78ndash83 2012

[60] D H Lee S K Behera J W Kim and H-S Park ldquoMethaneproduction potential of leachate generated from Korean foodwaste recycling facilities a lab-scale studyrdquoWaste Managementvol 29 no 2 pp 876ndash882 2009

[61] R Goel T Tokutomi and H Yasui ldquoAnaerobic digestion ofexcess activated sludge with ozone pretreatmentrdquoWater Scienceand Technology vol 47 no 12 pp 207ndash214 2003

[62] K M Mittal Biogas Systems Principles and Application NewAge International New Delhi India 1996

[63] Zeshan O P Karthikeyan and C Visvanathan ldquoEffect ofCN ratio and ammonia-N accumulation in a pilot-scale ther-mophilic dry anaerobic digesterrdquo Bioresource Technology vol113 pp 294ndash302 2012

[64] W Zhong L Chi Y Luo Z Zhang Z Zhang and W-M WuldquoEnhanced methane production from Taihu Lake blue algaeby anaerobic co-digestion with corn straw in continuous feeddigestersrdquo Bioresource Technology vol 134 pp 264ndash270 2013

[65] S Park and Y Li ldquoEvaluation of methane production andmacronutrient degradation in the anaerobic co-digestion ofalgae biomass residue and lipid wasterdquo Bioresource Technologyvol 111 pp 42ndash48 2012

[66] H-W Yen and D E Brune ldquoAnaerobic co-digestion of algalsludge and waste paper to produce methanerdquo BioresourceTechnology vol 98 no 1 pp 130ndash134 2007

[67] J Van Brakel The Ignis Fatuus of Biogas Small-Scale AnaerobicDigesters (lsquoBiogas Plantsrsquo) A Critical Review of the Premdash1970Literature Delft University Press 1980

[68] I Siegert andC Banks ldquoThe effect of volatile fatty acid additionson the anaerobic digestion of cellulose and glucose in batchreactorsrdquo Process Biochemistry vol 40 no 11 pp 3412ndash34182005

[69] K Vijayaraghavan V S Varma and S P Kamala NalinildquoHydrogen generation from biological solid waste of milkprocessing effluent treatment planrdquo International Journal ofCurrent Trends and Resources vol 1 pp 17ndash23 2012

[70] R A Labatut L T Angenent and N R Scott ldquoBiochemicalmethane potential and biodegradability of complex organicsubstratesrdquo Bioresource Technology vol 102 no 3 pp 2255ndash2264 2011

16 BioMed Research International

[71] H Bouallagui Y Touhami R Ben Cheikh and M HamdildquoBioreactor performance in anaerobic digestion of fruit andvegetable wastesrdquo Process Biochemistry vol 40 no 3-4 pp 989ndash995 2005

[72] P D Cotter and C Hill ldquoSurviving the acid test responses ofgram-positive bacteria to low pHrdquoMicrobiology and MolecularBiology Reviews vol 67 no 3 pp 429ndash453 2003

[73] B Zhang L-L Zhang S-C Zhang H-Z Shi and W-M CaildquoThe influence of pH on hydrolysis and acidogenesis of kitchenwastes in two-phase anaerobic digestionrdquo Environmental Tech-nology vol 26 no 3 pp 329ndash339 2005

[74] J A Eastman and J F Ferguson ldquoSolubilisation of particulateorganic carbon during theacid phase of ADrdquo Journal of theWater Pollution Control Federation vol 53 pp 352ndash366 1981

[75] E P Taiganides ldquoBiomass-energy recovery from animal wastePart IrdquoWorld Animal Review vol 35 p 2 1980

[76] N Nagao N Tajima M Kawai et al ldquoMaximum organicloading rate for the single-stage wet anaerobic digestion of foodwasterdquo Bioresource Technology vol 118 pp 210ndash218 2012

[77] E Tampio S Ervasti T Paavola S Heaven C Banks and JRintala ldquoAnaerobic digestion of autoclaved and untreated foodwasterdquoWaste Management vol 34 no 2 pp 370ndash377 2014

[78] F O Agyeman and W Tao ldquoAnaerobic co-digestion of foodwaste and dairy manure effects of food waste particle size andorganic loading raterdquo Journal of Environmental Managementvol 133 pp 268ndash274 2014

[79] M Carlsson A Lagerkvist and H Ecke ldquoElectroporationfor enhanced Methane yield from municipal solid wasterdquo inProceedings of the Moving Organic Waste Recycling TowardsResource Management and Biobased Economy (ORBIT rsquo08) vol6 pp 1ndash8 Wageningen the Netherlands October 2008

[80] L H Hagen V Vivekanand R Linjordet P B Pope V GH Eijsink and S J Horn ldquoMicrobial community structureand dynamics during co-digestion of whey permeate and cowmanure in continuous stirred tank reactor systemsrdquo BioresourceTechnology vol 171 pp 350ndash359 2014

[81] O Yenigun and B Demirel ldquoAmmonia inhibition in anaerobicdigestion a reviewrdquo Process Biochemistry vol 48 no 5-6 pp901ndash911 2013

[82] M J Whelan T Everitt and R Villa ldquoA mass transfer modelof ammonia volatilisation from anaerobic digestaterdquo WasteManagement vol 30 no 10 pp 1808ndash1812 2010

[83] M Walker K Iyer S Heaven and C J Banks ldquoAmmoniaremoval in anaerobic digestion by biogas stripping an evalu-ation of process alternatives using a first order rate model basedon experimental findingsrdquo Chemical Engineering Journal vol178 pp 138ndash145 2011

[84] C Zhang H Su and T Tan ldquoBatch and semi-continuousanaerobic digestion of foodwaste in a dual solidndashliquid systemrdquoBioresource Technology vol 145 pp 10ndash16 2013

[85] F Raposo V Fernandez-Cegrı M A de la Rubia et al ldquoBio-chemical methane potential (BMP) of solid organic substratesevaluation of anaerobic biodegradability using data from aninternational interlaboratory studyrdquo Journal of Chemical Tech-nology and Biotechnology vol 86 no 8 pp 1088ndash1098 2011

[86] P Jin S K Bhattacharya C J Williams and H Zhang ldquoEffectsof sulfide addition on copper inhibition in methanogenicsystemsrdquoWater Research vol 32 no 4 pp 977ndash988 1998

[87] A Schattauer E Abdoun P Weiland M Plochl and MHeiermann ldquoAbundance of trace elements in demonstrationbiogas plantsrdquo Biosystems Engineering vol 108 no 1 pp 57ndash652011

[88] V Facchin C Cavinato F Fatone P Pavan F Cecchi andD Bolzonella ldquoEffect of trace element supplementation on themesophilic anaerobic digestion of foodwaste in batch trials theinfluence of inoculum originrdquo Biochemical Engineering Journalvol 70 pp 71ndash77 2013

[89] C A Jackson-Moss J R Duncan and D R Cooper ldquoThe effectof calciumon anaerobic digestionrdquoBiotechnology Letters vol 11no 3 pp 219ndash224 1989

[90] H Q Yu J H Tay and H H P Fang ldquoThe roles of calciumin sludge granulation during UASB reactor start-uprdquo WaterResearch vol 35 no 4 pp 1052ndash1060 2001

[91] C-Y Lin and C-C Chen ldquoEffect of heavy metals on themethanogenic UASB granulerdquoWater Research vol 33 no 2 pp409ndash416 1999

[92] G Zayed and JWinter ldquoInhibition ofmethane production fromwhey by heavy metalsmdashprotective effect of sulfiderdquo AppliedMicrobiology andBiotechnology vol 53 no 6 pp 726ndash731 2000

[93] S Ghosh M P Henry and R W Christopher ldquoHemicelluloseconversion by anaerobic digestionrdquo Biomass vol 6 no 4 pp257ndash269 1985

[94] E Elbeshbishy G Nakhla andHHafez ldquoBiochemicalmethanepotential (BMP) of food waste and primary sludge influenceof inoculum pre-incubation and inoculum sourcerdquo BioresourceTechnology vol 110 pp 18ndash25 2012

[95] M S Lisboa and S Lansing ldquoCharacterizing food waste sub-strates for co-digestion through biochemical methane potential(BMP) experimentsrdquo Waste Management vol 33 no 12 pp2664ndash2669 2013

[96] M Murto L Bjornsson H Rosqvist and I Bohn ldquoEvaluatingthe biogas potential of the dry fraction from pretreatment offood waste from householdsrdquoWaste Management vol 33 no 5pp 1282ndash1289 2013

[97] J Marin K J Kennedy and C Eskicioglu ldquoEffect of microwaveirradiation on anaerobic degradability of model kitchen wasterdquoWaste Management vol 30 no 10 pp 1772ndash1779 2010

[98] K Izumi Y K Okishio C Niwa S Yamamoto and T TodaldquoEffects of particle size on anaerobic digestion of food wasterdquoInternational Journal of Bio-Deterioration Biodegradation vol64 no 7 pp 601ndash608 2010

[99] J Ma T H Duong M Smits W Verstraete and M CarballaldquoEnhanced biomethanation of kitchen waste by different pre-treatmentsrdquo Bioresource Technology vol 102 no 2 pp 592ndash5992011

[100] J-Y Wang X-Y Liu J C M Kao and O Stabnikova ldquoDiges-tion of pre-treated food waste in a hybrid anaerobic solid-liquid (HASL) systemrdquo Journal of Chemical Technology andBiotechnology vol 81 no 3 pp 345ndash351 2006

[101] O Stabnikova X Y Liu and J Y Wang ldquoDigestion offrozenthawed food waste in the hybrid anaerobic solid-liquidsystemrdquoWaste Management vol 28 no 9 pp 1654ndash1659 2008

[102] X Liu W Wang X Gao Y Zhou and R Shen ldquoEffect ofthermal pretreatment on the physical and chemical propertiesof municipal biomass wasterdquoWaste Management vol 32 no 2pp 249ndash255 2012

[103] SWKim J Y Park J K Kim et al ldquoDevelopment of amodifiedthree-stage methane production process using food wastesrdquoApplied Biochemistry and Biotechnology vol 84ndash86 pp 731ndash7412000

[104] J W Lim and J-Y Wang ldquoEnhanced hydrolysis and methaneyield by applying microaeration pretreatment to the anaerobicco-digestion of brown water and food wasterdquo Waste Manage-ment vol 33 no 4 pp 813ndash819 2013

BioMed Research International 17

[105] L Neves R Oliveira and M M Alves ldquoCo-digestion of cowmanure food waste and intermittent input of fatrdquo BioresourceTechnology vol 100 no 6 pp 1957ndash1962 2009

[106] S G Kim ldquoSystem for separation of oil and sludge from foodwaste leachaterdquo Korea Patent 10-2010-0053719

[107] C-F Chu Y-Y Li K-Q Xu Y Ebie Y Inamori and H-NKong ldquoA pH- and temperature-phased two-stage process forhydrogen and methane production from food wasterdquo Interna-tional Journal of Hydrogen Energy vol 33 no 18 pp 4739ndash47462008

[108] JMassanet-Nicolau R Dinsdale A Guwy andG Shipley ldquoUseof real time gas production data for more accurate comparisonof continuous single-stage and two-stage fermentationrdquo Biore-source Technology vol 129 pp 561ndash567 2013

[109] Y Koike M-Z An Y-Q Tang et al ldquoProduction of fuelethanol andmethane from garbage by high-efficiency two-stagefermentation processrdquo Journal of Bioscience and Bioengineeringvol 108 no 6 pp 508ndash512 2009

[110] X Hai-LouW Jing-Yuan and T Joo-Hwa ldquoA hybrid anaerobicsolid-liquid bioreactor for food waste digestionrdquo BiotechnologyLetters vol 24 no 10 pp 757ndash761 2002

[111] Y Li S Y Park and J Zhu ldquoSolid-state anaerobic digestionfor methane production from organic wasterdquo Renewable andSustainable Energy Reviews vol 15 no 1 pp 821ndash826 2011

[112] L Appels J Baeyens J Degreve and R Dewil ldquoPrinciples andpotential of the anaerobic digestion of waste-activated sludgerdquoProgress in Energy and Combustion Science vol 34 no 6 pp755ndash781 2008

[113] O P Karthikeyan and C Visvanathan ldquoBio-energy recoveryfrom high-solid organic substrates by dry anaerobic bio-conversion processes a reviewrdquo Reviews in EnvironmentalScience and BioTechnology vol 12 no 3 pp 257ndash284 2013

[114] J Guendouz P Buffiere J CachoMCarrere and J-PDelgenesldquoDry anaerobic digestion in batch mode design and operationof a laboratory-scale completelymixed reactorrdquoWasteManage-ment vol 30 no 10 pp 1768ndash1771 2010

[115] L Yang F Xu X Ge and Y Li ldquoChallenges and strategiesfor solid-state anaerobic digestion of lignocellulosic biomassrdquoRenewable and Sustainable Energy Reviews vol 44 pp 824ndash8342015

[116] A Abbassi-Guendouz E Trably J Hamelin et al ldquoMicro-bial community signature of high-solid content methanogenicecosystemsrdquo Bioresource Technology vol 133 pp 256ndash262 2013

[117] J Lindmark E Thorin R Bel Fdhila and E Dahlquis ldquoProb-lems and possibilities with the implementation of simulationand modeling at a biogas plantrdquo in Proceedings of the Interna-tional Conference on Applied Energy (ICAE rsquo12) Suzhou ChinaJuly 2012

[118] I Angelidaki L Ellegaard and B K Ahring ldquoA mathematicalmodel for dynamic simulation of anaerobic digestion of com-plex substrates focusing on ammonia inhibitionrdquoBiotechnologyand Bioengineering vol 42 no 2 pp 159ndash166 1993

[119] S Kalyuzhnyi A Veeken and B Hamelers ldquoTwo-particlemodel of anaerobic solid state fermentationrdquoWater Science andTechnology vol 41 no 3 pp 43ndash50 2000

[120] D J Martin L G A Potts and V A Heslop ldquoReactionmechanisms in solid-state anaerobic digestion I The reactionfront hypothesisrdquo Process Safety and Environmental Protectionvol 81 no 3 pp 171ndash179 2003

[121] D J Martin ldquoA novel mathematical model of solid-statedigestionrdquo Biotechnology Letters vol 22 no 1 pp 91ndash94 2000

[122] V A Vavilin M Y Shchelkanov and S V Rytov ldquoEffect of masstransfer on concentration wave propagation during anaerobicdigestion of solidwasterdquoWater Research vol 36 no 9 pp 2405ndash2409 2002

[123] V A Vavilin L Y Lokshina J P Y Jokela and J A RintalaldquoModeling solid waste decompositionrdquo Bioresource Technologyvol 94 no 1 pp 69ndash81 2004

[124] V A Vavilin S V Rytov L Y Lokshina S G Pavlostathisand M A Barlaz ldquoDistributed model of solid waste anaerobicdigestion effects of leachate recirculation and pH adjustmentrdquoBiotechnology and Bioengineering vol 81 no 1 pp 66ndash73 2003

[125] V A Vavilin and I Angelidaki ldquoAnaerobic degradation of solidmaterial importance of initiation centers for methanogenesismixing intensity and 2D distributed modelrdquo Biotechnology andBioengineering vol 89 no 1 pp 113ndash122 2005

[126] V A Vavilin L Y Lokshina X Flotats and I AngelidakildquoAnaerobic digestion of solid material multidimensional mod-eling of continuous-flow reactor with non-uniform influentconcentration distributionsrdquo Biotechnology and Bioengineeringvol 97 no 2 pp 354ndash366 2007

[127] H J Eber ldquoSimulation of chemical reaction fronts in anaerobicdigestion of solid wasterdquo in Proceedings of the ComputationalScience and Its Applications (ICCSA rsquo03) pp 503ndash512 MontrealCanada May 2003

[128] H J Eberl ldquoThe role of spatio-temporal effects in anaerobicdigestion of solid wasterdquo Nonlinear Analysis Theory Methodsamp Applications vol 63 no 5ndash7 pp e1497ndashe1505 2005

[129] A Abbassi-Guendouz D Brockmann E Trably et al ldquoTotalsolids content drives high solid anaerobic digestion via masstransfer limitationrdquo Bioresource Technology vol 111 pp 55ndash612012

[130] J Bollon R Le-Hyaric H Benbelkacem and P BuffiereldquoDevelopment of a kinetic model for anaerobic dry digestionprocesses focus on acetate degradation and moisture contentrdquoBiochemical Engineering Journal vol 56 no 3 pp 212ndash218 2011

[131] F Liotta P Chatellier G Esposito et al ldquoModified AnaerobicDigestionModel No1 for dry and semi-dry anaerobic digestionof solid organic wasterdquo Environmental Technology vol 36 no5ndash8 pp 870ndash880 2015

[132] F Xu Z-W Wang L Tang and Y Li ldquoA mass diffusion-basedinterpretation of the effect of total solids content on solid-state anaerobic digestion of cellulosic biomassrdquo BioresourceTechnology vol 167 pp 178ndash185 2014

[133] S Pommier D Chenu M Quintard and X Lefebvre ldquoAlogistic model for the prediction of the influence of water onthe solid waste methanization in landfillsrdquo Biotechnology andBioengineering vol 97 no 3 pp 473ndash482 2007

[134] L A Fdez-Guelfo C Alvarez-Gallego D Sales and L IRomero Garcıa ldquoDry-thermophilic anaerobic digestion oforganic fraction of municipal solid waste methane productionmodelingrdquoWasteManagement vol 32 no 3 pp 382ndash388 2012

[135] J Fernandez M Perez and L I Romero ldquoKinetics ofmesophilic anaerobic digestion of the organic fraction ofmunicipal solid waste influence of initial total solid concen-trationrdquo Bioresource Technology vol 101 no 16 pp 6322ndash63282010

[136] L N Liew J Shi and Y Li ldquoMethane production from solid-state anaerobic digestion of lignocellulosic biomassrdquo Biomassand Bioenergy vol 46 pp 125ndash132 2012

[137] D Brown J Shi and Y Li ldquoComparison of solid-state to liquidanaerobic digestion of lignocellulosic feedstocks for biogasproductionrdquo Bioresource Technology vol 124 pp 379ndash386 2012

18 BioMed Research International

[138] X Tong L H Smith and P LMcCarty ldquoMethane fermentationof selected lignocellulosic materialsrdquo Biomass vol 21 no 4 pp239ndash255 1990

[139] J-C Motte R Escudie N Bernet J-P Delgenes J-P Steyerand C Dumas ldquoDynamic effect of total solid content low sub-strateinoculum ratio and particle size on solid-state anaerobicdigestionrdquo Bioresource Technology vol 144 pp 141ndash148 2013

[140] F Xu Z-W Wang and Y Li ldquoPredicting the methane yieldof lignocellulosic biomass in mesophilic solid-state anaerobicdigestion based on feedstock characteristics and process param-etersrdquo Bioresource Technology vol 173 pp 168ndash176 2014

[141] F Xu Y Li and Z-W Wang ldquoMathematical modeling of solid-state anaerobic digestionrdquo Progress in Energy and CombustionScience vol 51 pp 49ndash66 2015

[142] L Li Q He Y Ma X Wang and X Peng ldquoDynamicsof microbial community in a mesophilic anaerobic digestertreating food waste relationship between community structureand process stabilityrdquo Bioresource Technology vol 189 pp 113ndash120 2015

[143] J W Lim C-L Chen I J R Ho and J-Y Wang ldquoStudy ofmicrobial community and biodegradation efficiency for single-and two-phase anaerobic co-digestion of brown water and foodwasterdquo Bioresource Technology vol 147 pp 193ndash201 2013

[144] S-K Cho W-T Im D-H Kim M-H Kim H-S Shin and S-E Oh ldquoDry anaerobic digestion of foodwaste undermesophilicconditions performance and methanogenic community analy-sisrdquo Bioresource Technology vol 131 pp 210ndash217 2013

[145] S Wan L Sun J Sun and W Luo ldquoBiogas production andmicrobial community change during the Co-digestion of foodwaste with chinese silver grass in a single-stage anaerobicreactorrdquo Biotechnology and Bioprocess Engineering vol 18 no5 pp 1022ndash1030 2013

[146] L Li Q He Y Ma X Wang and X Peng ldquoA mesophilicanaerobic digester for treating food waste process stability andmicrobial community analysis using pyrosequencingrdquo Micro-bial Cell Factories vol 15 no 1 article no 65 2016

[147] M Zamanzadeh L H Hagen K Svensson R Linjordet and SJ Horn ldquoAnaerobic digestion of food wastemdasheffect of recircula-tion and temperature on performance andmicrobiologyrdquoWaterResearch vol 96 pp 246ndash254 2016

[148] M Gulhane P Pandit A Khardenavis and D Singh ldquoStudyof microbial community plasticity for anaerobic digestionof vegetable waste in Anaerobic Baffled Reactorrdquo RenewableEnergy vol 96 pp 246ndash254 2016

[149] X Guo C Wang F Sun W Zhu and W Wu ldquoA comparisonof microbial characteristics between the thermophilic andmesophilic anaerobic digesters exposed to elevated food wasteloadingsrdquo Bioresource Technology vol 152 pp 420ndash428 2014

[150] F Ali Shah Q Mahmood M Maroof Shah A Pervez and SAhmadAsad ldquoMicrobial ecology of anaerobic digesters the keyplayers of anaerobiosisrdquo The Scientific World Journal vol 2014Article ID 183752 21 pages 2014

[151] H Bouallagui M Torrijos J J Godon et al ldquoMicrobial mon-itoring by molecular tools of a two-phase anaerobic bioreactortreating fruit and vegetable wastesrdquo Biotechnology Letters vol26 no 10 pp 857ndash862 2004

[152] L Manoharan S K Kushwaha K Hedlund and D AhrenldquoCaptured metagenomics large-scale targeting of genes basedon rsquosequence capturersquo reveals functional diversity in soilsrdquoDNAResearch vol 22 no 6 pp 451ndash460 2015

[153] H Sanguin B Remenant A Dechesne et al ldquoPotential ofa 16S rRNA-based taxonomic microarray for analyzing the

rhizosphere effects ofmaize onAgrobacteriumspp and bacterialcommunitiesrdquoApplied and EnvironmentalMicrobiology vol 72no 6 pp 4302ndash4312 2006

[154] H Sanguin A Herrera C Oger-Desfeux et al ldquoDevelopmentand validation of a prototype 16S rRNA-based taxonomicmicroarray for Alphaproteobacteriardquo Environmental Microbiol-ogy vol 8 no 2 pp 289ndash307 2006

[155] M Kyselkova J Kopecky T Felfoldi et al ldquoDevelopment of a16S rRNA gene-based prototype microarray for the detection ofselected actinomycetes generardquo International Journal of Generaland Molecular Microbiology vol 94 no 3 pp 439ndash453 2008

[156] W-T Liu A D Mirzabekov and D A Stahl ldquoOptimization ofan oligonucleotide microchip for microbial identification stud-ies a non-equilibrium dissociation approachrdquo EnvironmentalMicrobiology vol 3 no 10 pp 619ndash629 2001

[157] S Schonmann A Loy C Wimmersberger et al ldquo16S rRNAgene-based phylogenetic microarray for simultaneous identifi-cation of members of the genus Burkholderiardquo EnvironmentalMicrobiology vol 11 no 4 pp 779ndash800 2009

[158] A E Warsen M J Krug S LaFrentz D R Stanek F JLoge and D R Call ldquoSimultaneous discrimination between15 fish pathogens by using 16S ribosomal DNA PCR and DNAmicroarraysrdquo Applied and Environmental Microbiology vol 70no 7 pp 4216ndash4221 2004

[159] I H Franke-Whittle S H Klammer and H Insam ldquoDesignand application of an oligonucleotide microarray for theinvestigation of compost microbial communitiesrdquo Journal ofMicrobiological Methods vol 62 no 1 pp 37ndash56 2005

[160] J Peplies C Lachmund F O Glockner and W Manz ldquoADNA microarray platform based on direct detection of rRNAfor characterization of freshwater sediment-related prokaryoticcommunitiesrdquoApplied and EnvironmentalMicrobiology vol 72no 7 pp 4829ndash4838 2006

[161] S Demaneche H Sanguin J Pote et al ldquoAntibiotic-resistantsoil bacteria in transgenic plant fieldsrdquo Proceedings of theNational Academy of Sciences of the United States of Americavol 105 no 10 pp 3957ndash3962 2008

[162] A Loy A Lehner N Lee et al ldquoOligonucleotide microarrayfor 16S rRNA gene-based detection of all recognized lineagesof sulfate-reducing prokaryotes in the environmentrdquo Appliedand Environmental Microbiology vol 68 no 10 pp 5064ndash50812002

[163] S Siripong J J Kelly D A Stahl and B E Rittmann ldquoImpactof prehybridization PCR amplification onmicroarray detectionof nitrifying bacteria in wastewater treatment plant samplesrdquoEnvironmental Microbiology vol 8 no 9 pp 1564ndash1574 2006

[164] S K Kushwaha L Manoharan T Meerupati K Hedlundand D Ahren ldquoErratum to MetCap a bioinformatics probedesign pipeline for large-scale targeted metagenomicsrdquo BMCBioinformatics vol 17 article 39 2016

[165] httpswwwilluminacomtechnologynext-generation-sequen-cingsequencing-technologyhtml

[166] httpswwwthermofishercominenhomelife-sciencesequen-cingnext-generation-sequencingion-torrent-next-generation-sequencing-workflowion-torrent-next-generation-sequencing-run-sequenceion-proton-system-for-next-generation-sequen-cinghtml

[167] httpwwwpacbcomproducts-and-servicespacbio-systemsrsii

[168] F J Azuaje M Heymann A-M Ternes et al ldquoBioinformaticsas a driver not a passenger of translational biomedical research

BioMed Research International 15

[37] H-W Kim J-Y Nam and H-S Shin ldquoA comparison studyon the high-rate co-digestion of sewage sludge and food wasteusing a temperature-phased anaerobic sequencing batch reactorsystemrdquo Bioresource Technology vol 102 no 15 pp 7272ndash72792011

[38] M Kumar Y-L Ou and J-G Lin ldquoCo-composting of greenwaste and food waste at low CN ratiordquoWasteManagement vol30 no 4 pp 602ndash609 2010

[39] R Rajagopal J W Lim Y Mao C-L Chen and J-Y WangldquoAnaerobic co-digestion of source segregated brown water(feces-without-urine) and food waste for Singapore contextrdquoScience of the Total Environment vol 443 pp 877ndash886 2013

[40] S E Nayono C Gallert and J Winter ldquoCo-digestion of presswater and food waste in a biowaste digester for improvement ofbiogas productionrdquo Bioresource Technology vol 101 no 18 pp6987ndash6993 2010

[41] L-H Wang Q Wang W Cai and X Sun ldquoInfluence ofmixing proportion on the solid-state anaerobic co-digestion ofdistillerrsquos grains and food wasterdquo Biosystems Engineering vol112 no 2 pp 130ndash137 2012

[42] K M Mittal Biogas Systems Policies Progress and ProspectsNew Age International New Delhi India 1997

[43] M P Bryant ldquoMicrobial methane production theoreticalaspectsrdquo Journal of Animal Science vol 48 no 1 pp 193ndash2011979

[44] B Schink ldquoEnergetics of syntrophic cooperation in metha-nogenic degradationrdquo Microbiology and Molecular BiologyReviews vol 61 no 2 pp 262ndash280 1997

[45] M E Griffin K D McMahon R I Mackie and L RaskinldquoMethanogenic population dynamics during start-up of anaer-obic digesters treating municipal solid waste and biosolidsrdquoBiotechnology and Bioengineering vol 57 no 3 pp 342ndash3551998

[46] D Karakashev D J Batstone and I Angelidaki ldquoInfluence ofenvironmental conditions on methanogenic compositions inanaerobic biogas reactorsrdquo Applied and Environmental Micro-biology vol 71 no 1 pp 331ndash338 2005

[47] AM Viturtia J Mata-Alvarez F Cecchi andG Fazzini ldquoTwo-phase anaerobic digestion of a mixture of fruit and vegetablewastesrdquo Biological Wastes vol 29 no 3 pp 189ndash199 1989

[48] J K Cho S C Park and H N Chang ldquoBiochemical methanepotential and solid state anaerobic digestion of Korean foodwastesrdquo Bioresource Technology vol 52 no 3 pp 245ndash253 1995

[49] Z Yong YDong X Zhang andT Tan ldquoAnaerobic co-digestionof food waste and straw for biogas productionrdquo RenewableEnergy vol 78 pp 527ndash530 2015

[50] N Curry and P Pillay ldquoBiogas prediction and design of a foodwaste to energy system for the urban environmentrdquo RenewableEnergy vol 41 pp 200ndash209 2012

[51] R E Anderson Biological Path to Self-Reliance Van NostrandReinhold Company New York NY USA 1979

[52] P Dhevagi K Ramasamy and G Oblisami Biological NitrogenFixation and Biogas Technology Tamilnadu Agricultural Uni-versity 1992

[53] S H Zinder ldquoPhysiological ecology of methanogensrdquo inMethanogenesis Ecology Physiology Biochemistry andGeneticsJ G Ferry Ed pp 128ndash206 Chapman and Hall New York NYUSA 1993

[54] L Arsova Anaerobic digestion of food waste current statusproblems and an alternative product [MS thesis] ColumbiaUniversity Berlin Germany 2010

[55] A C Van Haandel and G Lettinga Anaerobic SewageTreatmentmdashA Practical Guide for Regions with a Hot ClimateJohn Wiley amp Sons New York NY USA 1994

[56] H Bouallagui O Haouari Y Touhami R Ben Cheikh LMarouani and M Hamdi ldquoEffect of temperature on theperformance of an anaerobic tubular reactor treating fruit andvegetable wasterdquo Process Biochemistry vol 39 no 12 pp 2143ndash2148 2004

[57] J K Kim B R Oh Y N Chun and S W Kim ldquoEffects of tem-perature and hydraulic retention time on anaerobic digestion offood wasterdquo Journal of Bioscience and Bioengineering vol 102no 4 pp 328ndash332 2006

[58] C Gou Z Yang J Huang H Wang H Xu and L WangldquoEffects of temperature and organic loading rate on the perfor-mance and microbial community of anaerobic co-digestion ofwaste activated sludge and food wasterdquo Chemosphere vol 105pp 146ndash151 2014

[59] X Wang G Yang Y Feng G Ren and X Han ldquoOptimizingfeeding composition and carbon-nitrogen ratios for improvedmethane yield during anaerobic co-digestion of dairy chickenmanure and wheat strawrdquo Bioresource Technology vol 120 pp78ndash83 2012

[60] D H Lee S K Behera J W Kim and H-S Park ldquoMethaneproduction potential of leachate generated from Korean foodwaste recycling facilities a lab-scale studyrdquoWaste Managementvol 29 no 2 pp 876ndash882 2009

[61] R Goel T Tokutomi and H Yasui ldquoAnaerobic digestion ofexcess activated sludge with ozone pretreatmentrdquoWater Scienceand Technology vol 47 no 12 pp 207ndash214 2003

[62] K M Mittal Biogas Systems Principles and Application NewAge International New Delhi India 1996

[63] Zeshan O P Karthikeyan and C Visvanathan ldquoEffect ofCN ratio and ammonia-N accumulation in a pilot-scale ther-mophilic dry anaerobic digesterrdquo Bioresource Technology vol113 pp 294ndash302 2012

[64] W Zhong L Chi Y Luo Z Zhang Z Zhang and W-M WuldquoEnhanced methane production from Taihu Lake blue algaeby anaerobic co-digestion with corn straw in continuous feeddigestersrdquo Bioresource Technology vol 134 pp 264ndash270 2013

[65] S Park and Y Li ldquoEvaluation of methane production andmacronutrient degradation in the anaerobic co-digestion ofalgae biomass residue and lipid wasterdquo Bioresource Technologyvol 111 pp 42ndash48 2012

[66] H-W Yen and D E Brune ldquoAnaerobic co-digestion of algalsludge and waste paper to produce methanerdquo BioresourceTechnology vol 98 no 1 pp 130ndash134 2007

[67] J Van Brakel The Ignis Fatuus of Biogas Small-Scale AnaerobicDigesters (lsquoBiogas Plantsrsquo) A Critical Review of the Premdash1970Literature Delft University Press 1980

[68] I Siegert andC Banks ldquoThe effect of volatile fatty acid additionson the anaerobic digestion of cellulose and glucose in batchreactorsrdquo Process Biochemistry vol 40 no 11 pp 3412ndash34182005

[69] K Vijayaraghavan V S Varma and S P Kamala NalinildquoHydrogen generation from biological solid waste of milkprocessing effluent treatment planrdquo International Journal ofCurrent Trends and Resources vol 1 pp 17ndash23 2012

[70] R A Labatut L T Angenent and N R Scott ldquoBiochemicalmethane potential and biodegradability of complex organicsubstratesrdquo Bioresource Technology vol 102 no 3 pp 2255ndash2264 2011

16 BioMed Research International

[71] H Bouallagui Y Touhami R Ben Cheikh and M HamdildquoBioreactor performance in anaerobic digestion of fruit andvegetable wastesrdquo Process Biochemistry vol 40 no 3-4 pp 989ndash995 2005

[72] P D Cotter and C Hill ldquoSurviving the acid test responses ofgram-positive bacteria to low pHrdquoMicrobiology and MolecularBiology Reviews vol 67 no 3 pp 429ndash453 2003

[73] B Zhang L-L Zhang S-C Zhang H-Z Shi and W-M CaildquoThe influence of pH on hydrolysis and acidogenesis of kitchenwastes in two-phase anaerobic digestionrdquo Environmental Tech-nology vol 26 no 3 pp 329ndash339 2005

[74] J A Eastman and J F Ferguson ldquoSolubilisation of particulateorganic carbon during theacid phase of ADrdquo Journal of theWater Pollution Control Federation vol 53 pp 352ndash366 1981

[75] E P Taiganides ldquoBiomass-energy recovery from animal wastePart IrdquoWorld Animal Review vol 35 p 2 1980

[76] N Nagao N Tajima M Kawai et al ldquoMaximum organicloading rate for the single-stage wet anaerobic digestion of foodwasterdquo Bioresource Technology vol 118 pp 210ndash218 2012

[77] E Tampio S Ervasti T Paavola S Heaven C Banks and JRintala ldquoAnaerobic digestion of autoclaved and untreated foodwasterdquoWaste Management vol 34 no 2 pp 370ndash377 2014

[78] F O Agyeman and W Tao ldquoAnaerobic co-digestion of foodwaste and dairy manure effects of food waste particle size andorganic loading raterdquo Journal of Environmental Managementvol 133 pp 268ndash274 2014

[79] M Carlsson A Lagerkvist and H Ecke ldquoElectroporationfor enhanced Methane yield from municipal solid wasterdquo inProceedings of the Moving Organic Waste Recycling TowardsResource Management and Biobased Economy (ORBIT rsquo08) vol6 pp 1ndash8 Wageningen the Netherlands October 2008

[80] L H Hagen V Vivekanand R Linjordet P B Pope V GH Eijsink and S J Horn ldquoMicrobial community structureand dynamics during co-digestion of whey permeate and cowmanure in continuous stirred tank reactor systemsrdquo BioresourceTechnology vol 171 pp 350ndash359 2014

[81] O Yenigun and B Demirel ldquoAmmonia inhibition in anaerobicdigestion a reviewrdquo Process Biochemistry vol 48 no 5-6 pp901ndash911 2013

[82] M J Whelan T Everitt and R Villa ldquoA mass transfer modelof ammonia volatilisation from anaerobic digestaterdquo WasteManagement vol 30 no 10 pp 1808ndash1812 2010

[83] M Walker K Iyer S Heaven and C J Banks ldquoAmmoniaremoval in anaerobic digestion by biogas stripping an evalu-ation of process alternatives using a first order rate model basedon experimental findingsrdquo Chemical Engineering Journal vol178 pp 138ndash145 2011

[84] C Zhang H Su and T Tan ldquoBatch and semi-continuousanaerobic digestion of foodwaste in a dual solidndashliquid systemrdquoBioresource Technology vol 145 pp 10ndash16 2013

[85] F Raposo V Fernandez-Cegrı M A de la Rubia et al ldquoBio-chemical methane potential (BMP) of solid organic substratesevaluation of anaerobic biodegradability using data from aninternational interlaboratory studyrdquo Journal of Chemical Tech-nology and Biotechnology vol 86 no 8 pp 1088ndash1098 2011

[86] P Jin S K Bhattacharya C J Williams and H Zhang ldquoEffectsof sulfide addition on copper inhibition in methanogenicsystemsrdquoWater Research vol 32 no 4 pp 977ndash988 1998

[87] A Schattauer E Abdoun P Weiland M Plochl and MHeiermann ldquoAbundance of trace elements in demonstrationbiogas plantsrdquo Biosystems Engineering vol 108 no 1 pp 57ndash652011

[88] V Facchin C Cavinato F Fatone P Pavan F Cecchi andD Bolzonella ldquoEffect of trace element supplementation on themesophilic anaerobic digestion of foodwaste in batch trials theinfluence of inoculum originrdquo Biochemical Engineering Journalvol 70 pp 71ndash77 2013

[89] C A Jackson-Moss J R Duncan and D R Cooper ldquoThe effectof calciumon anaerobic digestionrdquoBiotechnology Letters vol 11no 3 pp 219ndash224 1989

[90] H Q Yu J H Tay and H H P Fang ldquoThe roles of calciumin sludge granulation during UASB reactor start-uprdquo WaterResearch vol 35 no 4 pp 1052ndash1060 2001

[91] C-Y Lin and C-C Chen ldquoEffect of heavy metals on themethanogenic UASB granulerdquoWater Research vol 33 no 2 pp409ndash416 1999

[92] G Zayed and JWinter ldquoInhibition ofmethane production fromwhey by heavy metalsmdashprotective effect of sulfiderdquo AppliedMicrobiology andBiotechnology vol 53 no 6 pp 726ndash731 2000

[93] S Ghosh M P Henry and R W Christopher ldquoHemicelluloseconversion by anaerobic digestionrdquo Biomass vol 6 no 4 pp257ndash269 1985

[94] E Elbeshbishy G Nakhla andHHafez ldquoBiochemicalmethanepotential (BMP) of food waste and primary sludge influenceof inoculum pre-incubation and inoculum sourcerdquo BioresourceTechnology vol 110 pp 18ndash25 2012

[95] M S Lisboa and S Lansing ldquoCharacterizing food waste sub-strates for co-digestion through biochemical methane potential(BMP) experimentsrdquo Waste Management vol 33 no 12 pp2664ndash2669 2013

[96] M Murto L Bjornsson H Rosqvist and I Bohn ldquoEvaluatingthe biogas potential of the dry fraction from pretreatment offood waste from householdsrdquoWaste Management vol 33 no 5pp 1282ndash1289 2013

[97] J Marin K J Kennedy and C Eskicioglu ldquoEffect of microwaveirradiation on anaerobic degradability of model kitchen wasterdquoWaste Management vol 30 no 10 pp 1772ndash1779 2010

[98] K Izumi Y K Okishio C Niwa S Yamamoto and T TodaldquoEffects of particle size on anaerobic digestion of food wasterdquoInternational Journal of Bio-Deterioration Biodegradation vol64 no 7 pp 601ndash608 2010

[99] J Ma T H Duong M Smits W Verstraete and M CarballaldquoEnhanced biomethanation of kitchen waste by different pre-treatmentsrdquo Bioresource Technology vol 102 no 2 pp 592ndash5992011

[100] J-Y Wang X-Y Liu J C M Kao and O Stabnikova ldquoDiges-tion of pre-treated food waste in a hybrid anaerobic solid-liquid (HASL) systemrdquo Journal of Chemical Technology andBiotechnology vol 81 no 3 pp 345ndash351 2006

[101] O Stabnikova X Y Liu and J Y Wang ldquoDigestion offrozenthawed food waste in the hybrid anaerobic solid-liquidsystemrdquoWaste Management vol 28 no 9 pp 1654ndash1659 2008

[102] X Liu W Wang X Gao Y Zhou and R Shen ldquoEffect ofthermal pretreatment on the physical and chemical propertiesof municipal biomass wasterdquoWaste Management vol 32 no 2pp 249ndash255 2012

[103] SWKim J Y Park J K Kim et al ldquoDevelopment of amodifiedthree-stage methane production process using food wastesrdquoApplied Biochemistry and Biotechnology vol 84ndash86 pp 731ndash7412000

[104] J W Lim and J-Y Wang ldquoEnhanced hydrolysis and methaneyield by applying microaeration pretreatment to the anaerobicco-digestion of brown water and food wasterdquo Waste Manage-ment vol 33 no 4 pp 813ndash819 2013

BioMed Research International 17

[105] L Neves R Oliveira and M M Alves ldquoCo-digestion of cowmanure food waste and intermittent input of fatrdquo BioresourceTechnology vol 100 no 6 pp 1957ndash1962 2009

[106] S G Kim ldquoSystem for separation of oil and sludge from foodwaste leachaterdquo Korea Patent 10-2010-0053719

[107] C-F Chu Y-Y Li K-Q Xu Y Ebie Y Inamori and H-NKong ldquoA pH- and temperature-phased two-stage process forhydrogen and methane production from food wasterdquo Interna-tional Journal of Hydrogen Energy vol 33 no 18 pp 4739ndash47462008

[108] JMassanet-Nicolau R Dinsdale A Guwy andG Shipley ldquoUseof real time gas production data for more accurate comparisonof continuous single-stage and two-stage fermentationrdquo Biore-source Technology vol 129 pp 561ndash567 2013

[109] Y Koike M-Z An Y-Q Tang et al ldquoProduction of fuelethanol andmethane from garbage by high-efficiency two-stagefermentation processrdquo Journal of Bioscience and Bioengineeringvol 108 no 6 pp 508ndash512 2009

[110] X Hai-LouW Jing-Yuan and T Joo-Hwa ldquoA hybrid anaerobicsolid-liquid bioreactor for food waste digestionrdquo BiotechnologyLetters vol 24 no 10 pp 757ndash761 2002

[111] Y Li S Y Park and J Zhu ldquoSolid-state anaerobic digestionfor methane production from organic wasterdquo Renewable andSustainable Energy Reviews vol 15 no 1 pp 821ndash826 2011

[112] L Appels J Baeyens J Degreve and R Dewil ldquoPrinciples andpotential of the anaerobic digestion of waste-activated sludgerdquoProgress in Energy and Combustion Science vol 34 no 6 pp755ndash781 2008

[113] O P Karthikeyan and C Visvanathan ldquoBio-energy recoveryfrom high-solid organic substrates by dry anaerobic bio-conversion processes a reviewrdquo Reviews in EnvironmentalScience and BioTechnology vol 12 no 3 pp 257ndash284 2013

[114] J Guendouz P Buffiere J CachoMCarrere and J-PDelgenesldquoDry anaerobic digestion in batch mode design and operationof a laboratory-scale completelymixed reactorrdquoWasteManage-ment vol 30 no 10 pp 1768ndash1771 2010

[115] L Yang F Xu X Ge and Y Li ldquoChallenges and strategiesfor solid-state anaerobic digestion of lignocellulosic biomassrdquoRenewable and Sustainable Energy Reviews vol 44 pp 824ndash8342015

[116] A Abbassi-Guendouz E Trably J Hamelin et al ldquoMicro-bial community signature of high-solid content methanogenicecosystemsrdquo Bioresource Technology vol 133 pp 256ndash262 2013

[117] J Lindmark E Thorin R Bel Fdhila and E Dahlquis ldquoProb-lems and possibilities with the implementation of simulationand modeling at a biogas plantrdquo in Proceedings of the Interna-tional Conference on Applied Energy (ICAE rsquo12) Suzhou ChinaJuly 2012

[118] I Angelidaki L Ellegaard and B K Ahring ldquoA mathematicalmodel for dynamic simulation of anaerobic digestion of com-plex substrates focusing on ammonia inhibitionrdquoBiotechnologyand Bioengineering vol 42 no 2 pp 159ndash166 1993

[119] S Kalyuzhnyi A Veeken and B Hamelers ldquoTwo-particlemodel of anaerobic solid state fermentationrdquoWater Science andTechnology vol 41 no 3 pp 43ndash50 2000

[120] D J Martin L G A Potts and V A Heslop ldquoReactionmechanisms in solid-state anaerobic digestion I The reactionfront hypothesisrdquo Process Safety and Environmental Protectionvol 81 no 3 pp 171ndash179 2003

[121] D J Martin ldquoA novel mathematical model of solid-statedigestionrdquo Biotechnology Letters vol 22 no 1 pp 91ndash94 2000

[122] V A Vavilin M Y Shchelkanov and S V Rytov ldquoEffect of masstransfer on concentration wave propagation during anaerobicdigestion of solidwasterdquoWater Research vol 36 no 9 pp 2405ndash2409 2002

[123] V A Vavilin L Y Lokshina J P Y Jokela and J A RintalaldquoModeling solid waste decompositionrdquo Bioresource Technologyvol 94 no 1 pp 69ndash81 2004

[124] V A Vavilin S V Rytov L Y Lokshina S G Pavlostathisand M A Barlaz ldquoDistributed model of solid waste anaerobicdigestion effects of leachate recirculation and pH adjustmentrdquoBiotechnology and Bioengineering vol 81 no 1 pp 66ndash73 2003

[125] V A Vavilin and I Angelidaki ldquoAnaerobic degradation of solidmaterial importance of initiation centers for methanogenesismixing intensity and 2D distributed modelrdquo Biotechnology andBioengineering vol 89 no 1 pp 113ndash122 2005

[126] V A Vavilin L Y Lokshina X Flotats and I AngelidakildquoAnaerobic digestion of solid material multidimensional mod-eling of continuous-flow reactor with non-uniform influentconcentration distributionsrdquo Biotechnology and Bioengineeringvol 97 no 2 pp 354ndash366 2007

[127] H J Eber ldquoSimulation of chemical reaction fronts in anaerobicdigestion of solid wasterdquo in Proceedings of the ComputationalScience and Its Applications (ICCSA rsquo03) pp 503ndash512 MontrealCanada May 2003

[128] H J Eberl ldquoThe role of spatio-temporal effects in anaerobicdigestion of solid wasterdquo Nonlinear Analysis Theory Methodsamp Applications vol 63 no 5ndash7 pp e1497ndashe1505 2005

[129] A Abbassi-Guendouz D Brockmann E Trably et al ldquoTotalsolids content drives high solid anaerobic digestion via masstransfer limitationrdquo Bioresource Technology vol 111 pp 55ndash612012

[130] J Bollon R Le-Hyaric H Benbelkacem and P BuffiereldquoDevelopment of a kinetic model for anaerobic dry digestionprocesses focus on acetate degradation and moisture contentrdquoBiochemical Engineering Journal vol 56 no 3 pp 212ndash218 2011

[131] F Liotta P Chatellier G Esposito et al ldquoModified AnaerobicDigestionModel No1 for dry and semi-dry anaerobic digestionof solid organic wasterdquo Environmental Technology vol 36 no5ndash8 pp 870ndash880 2015

[132] F Xu Z-W Wang L Tang and Y Li ldquoA mass diffusion-basedinterpretation of the effect of total solids content on solid-state anaerobic digestion of cellulosic biomassrdquo BioresourceTechnology vol 167 pp 178ndash185 2014

[133] S Pommier D Chenu M Quintard and X Lefebvre ldquoAlogistic model for the prediction of the influence of water onthe solid waste methanization in landfillsrdquo Biotechnology andBioengineering vol 97 no 3 pp 473ndash482 2007

[134] L A Fdez-Guelfo C Alvarez-Gallego D Sales and L IRomero Garcıa ldquoDry-thermophilic anaerobic digestion oforganic fraction of municipal solid waste methane productionmodelingrdquoWasteManagement vol 32 no 3 pp 382ndash388 2012

[135] J Fernandez M Perez and L I Romero ldquoKinetics ofmesophilic anaerobic digestion of the organic fraction ofmunicipal solid waste influence of initial total solid concen-trationrdquo Bioresource Technology vol 101 no 16 pp 6322ndash63282010

[136] L N Liew J Shi and Y Li ldquoMethane production from solid-state anaerobic digestion of lignocellulosic biomassrdquo Biomassand Bioenergy vol 46 pp 125ndash132 2012

[137] D Brown J Shi and Y Li ldquoComparison of solid-state to liquidanaerobic digestion of lignocellulosic feedstocks for biogasproductionrdquo Bioresource Technology vol 124 pp 379ndash386 2012

18 BioMed Research International

[138] X Tong L H Smith and P LMcCarty ldquoMethane fermentationof selected lignocellulosic materialsrdquo Biomass vol 21 no 4 pp239ndash255 1990

[139] J-C Motte R Escudie N Bernet J-P Delgenes J-P Steyerand C Dumas ldquoDynamic effect of total solid content low sub-strateinoculum ratio and particle size on solid-state anaerobicdigestionrdquo Bioresource Technology vol 144 pp 141ndash148 2013

[140] F Xu Z-W Wang and Y Li ldquoPredicting the methane yieldof lignocellulosic biomass in mesophilic solid-state anaerobicdigestion based on feedstock characteristics and process param-etersrdquo Bioresource Technology vol 173 pp 168ndash176 2014

[141] F Xu Y Li and Z-W Wang ldquoMathematical modeling of solid-state anaerobic digestionrdquo Progress in Energy and CombustionScience vol 51 pp 49ndash66 2015

[142] L Li Q He Y Ma X Wang and X Peng ldquoDynamicsof microbial community in a mesophilic anaerobic digestertreating food waste relationship between community structureand process stabilityrdquo Bioresource Technology vol 189 pp 113ndash120 2015

[143] J W Lim C-L Chen I J R Ho and J-Y Wang ldquoStudy ofmicrobial community and biodegradation efficiency for single-and two-phase anaerobic co-digestion of brown water and foodwasterdquo Bioresource Technology vol 147 pp 193ndash201 2013

[144] S-K Cho W-T Im D-H Kim M-H Kim H-S Shin and S-E Oh ldquoDry anaerobic digestion of foodwaste undermesophilicconditions performance and methanogenic community analy-sisrdquo Bioresource Technology vol 131 pp 210ndash217 2013

[145] S Wan L Sun J Sun and W Luo ldquoBiogas production andmicrobial community change during the Co-digestion of foodwaste with chinese silver grass in a single-stage anaerobicreactorrdquo Biotechnology and Bioprocess Engineering vol 18 no5 pp 1022ndash1030 2013

[146] L Li Q He Y Ma X Wang and X Peng ldquoA mesophilicanaerobic digester for treating food waste process stability andmicrobial community analysis using pyrosequencingrdquo Micro-bial Cell Factories vol 15 no 1 article no 65 2016

[147] M Zamanzadeh L H Hagen K Svensson R Linjordet and SJ Horn ldquoAnaerobic digestion of food wastemdasheffect of recircula-tion and temperature on performance andmicrobiologyrdquoWaterResearch vol 96 pp 246ndash254 2016

[148] M Gulhane P Pandit A Khardenavis and D Singh ldquoStudyof microbial community plasticity for anaerobic digestionof vegetable waste in Anaerobic Baffled Reactorrdquo RenewableEnergy vol 96 pp 246ndash254 2016

[149] X Guo C Wang F Sun W Zhu and W Wu ldquoA comparisonof microbial characteristics between the thermophilic andmesophilic anaerobic digesters exposed to elevated food wasteloadingsrdquo Bioresource Technology vol 152 pp 420ndash428 2014

[150] F Ali Shah Q Mahmood M Maroof Shah A Pervez and SAhmadAsad ldquoMicrobial ecology of anaerobic digesters the keyplayers of anaerobiosisrdquo The Scientific World Journal vol 2014Article ID 183752 21 pages 2014

[151] H Bouallagui M Torrijos J J Godon et al ldquoMicrobial mon-itoring by molecular tools of a two-phase anaerobic bioreactortreating fruit and vegetable wastesrdquo Biotechnology Letters vol26 no 10 pp 857ndash862 2004

[152] L Manoharan S K Kushwaha K Hedlund and D AhrenldquoCaptured metagenomics large-scale targeting of genes basedon rsquosequence capturersquo reveals functional diversity in soilsrdquoDNAResearch vol 22 no 6 pp 451ndash460 2015

[153] H Sanguin B Remenant A Dechesne et al ldquoPotential ofa 16S rRNA-based taxonomic microarray for analyzing the

rhizosphere effects ofmaize onAgrobacteriumspp and bacterialcommunitiesrdquoApplied and EnvironmentalMicrobiology vol 72no 6 pp 4302ndash4312 2006

[154] H Sanguin A Herrera C Oger-Desfeux et al ldquoDevelopmentand validation of a prototype 16S rRNA-based taxonomicmicroarray for Alphaproteobacteriardquo Environmental Microbiol-ogy vol 8 no 2 pp 289ndash307 2006

[155] M Kyselkova J Kopecky T Felfoldi et al ldquoDevelopment of a16S rRNA gene-based prototype microarray for the detection ofselected actinomycetes generardquo International Journal of Generaland Molecular Microbiology vol 94 no 3 pp 439ndash453 2008

[156] W-T Liu A D Mirzabekov and D A Stahl ldquoOptimization ofan oligonucleotide microchip for microbial identification stud-ies a non-equilibrium dissociation approachrdquo EnvironmentalMicrobiology vol 3 no 10 pp 619ndash629 2001

[157] S Schonmann A Loy C Wimmersberger et al ldquo16S rRNAgene-based phylogenetic microarray for simultaneous identifi-cation of members of the genus Burkholderiardquo EnvironmentalMicrobiology vol 11 no 4 pp 779ndash800 2009

[158] A E Warsen M J Krug S LaFrentz D R Stanek F JLoge and D R Call ldquoSimultaneous discrimination between15 fish pathogens by using 16S ribosomal DNA PCR and DNAmicroarraysrdquo Applied and Environmental Microbiology vol 70no 7 pp 4216ndash4221 2004

[159] I H Franke-Whittle S H Klammer and H Insam ldquoDesignand application of an oligonucleotide microarray for theinvestigation of compost microbial communitiesrdquo Journal ofMicrobiological Methods vol 62 no 1 pp 37ndash56 2005

[160] J Peplies C Lachmund F O Glockner and W Manz ldquoADNA microarray platform based on direct detection of rRNAfor characterization of freshwater sediment-related prokaryoticcommunitiesrdquoApplied and EnvironmentalMicrobiology vol 72no 7 pp 4829ndash4838 2006

[161] S Demaneche H Sanguin J Pote et al ldquoAntibiotic-resistantsoil bacteria in transgenic plant fieldsrdquo Proceedings of theNational Academy of Sciences of the United States of Americavol 105 no 10 pp 3957ndash3962 2008

[162] A Loy A Lehner N Lee et al ldquoOligonucleotide microarrayfor 16S rRNA gene-based detection of all recognized lineagesof sulfate-reducing prokaryotes in the environmentrdquo Appliedand Environmental Microbiology vol 68 no 10 pp 5064ndash50812002

[163] S Siripong J J Kelly D A Stahl and B E Rittmann ldquoImpactof prehybridization PCR amplification onmicroarray detectionof nitrifying bacteria in wastewater treatment plant samplesrdquoEnvironmental Microbiology vol 8 no 9 pp 1564ndash1574 2006

[164] S K Kushwaha L Manoharan T Meerupati K Hedlundand D Ahren ldquoErratum to MetCap a bioinformatics probedesign pipeline for large-scale targeted metagenomicsrdquo BMCBioinformatics vol 17 article 39 2016

[165] httpswwwilluminacomtechnologynext-generation-sequen-cingsequencing-technologyhtml

[166] httpswwwthermofishercominenhomelife-sciencesequen-cingnext-generation-sequencingion-torrent-next-generation-sequencing-workflowion-torrent-next-generation-sequencing-run-sequenceion-proton-system-for-next-generation-sequen-cinghtml

[167] httpwwwpacbcomproducts-and-servicespacbio-systemsrsii

[168] F J Azuaje M Heymann A-M Ternes et al ldquoBioinformaticsas a driver not a passenger of translational biomedical research

16 BioMed Research International

[71] H Bouallagui Y Touhami R Ben Cheikh and M HamdildquoBioreactor performance in anaerobic digestion of fruit andvegetable wastesrdquo Process Biochemistry vol 40 no 3-4 pp 989ndash995 2005

[72] P D Cotter and C Hill ldquoSurviving the acid test responses ofgram-positive bacteria to low pHrdquoMicrobiology and MolecularBiology Reviews vol 67 no 3 pp 429ndash453 2003

[73] B Zhang L-L Zhang S-C Zhang H-Z Shi and W-M CaildquoThe influence of pH on hydrolysis and acidogenesis of kitchenwastes in two-phase anaerobic digestionrdquo Environmental Tech-nology vol 26 no 3 pp 329ndash339 2005

[74] J A Eastman and J F Ferguson ldquoSolubilisation of particulateorganic carbon during theacid phase of ADrdquo Journal of theWater Pollution Control Federation vol 53 pp 352ndash366 1981

[75] E P Taiganides ldquoBiomass-energy recovery from animal wastePart IrdquoWorld Animal Review vol 35 p 2 1980

[76] N Nagao N Tajima M Kawai et al ldquoMaximum organicloading rate for the single-stage wet anaerobic digestion of foodwasterdquo Bioresource Technology vol 118 pp 210ndash218 2012

[77] E Tampio S Ervasti T Paavola S Heaven C Banks and JRintala ldquoAnaerobic digestion of autoclaved and untreated foodwasterdquoWaste Management vol 34 no 2 pp 370ndash377 2014

[78] F O Agyeman and W Tao ldquoAnaerobic co-digestion of foodwaste and dairy manure effects of food waste particle size andorganic loading raterdquo Journal of Environmental Managementvol 133 pp 268ndash274 2014

[79] M Carlsson A Lagerkvist and H Ecke ldquoElectroporationfor enhanced Methane yield from municipal solid wasterdquo inProceedings of the Moving Organic Waste Recycling TowardsResource Management and Biobased Economy (ORBIT rsquo08) vol6 pp 1ndash8 Wageningen the Netherlands October 2008

[80] L H Hagen V Vivekanand R Linjordet P B Pope V GH Eijsink and S J Horn ldquoMicrobial community structureand dynamics during co-digestion of whey permeate and cowmanure in continuous stirred tank reactor systemsrdquo BioresourceTechnology vol 171 pp 350ndash359 2014

[81] O Yenigun and B Demirel ldquoAmmonia inhibition in anaerobicdigestion a reviewrdquo Process Biochemistry vol 48 no 5-6 pp901ndash911 2013

[82] M J Whelan T Everitt and R Villa ldquoA mass transfer modelof ammonia volatilisation from anaerobic digestaterdquo WasteManagement vol 30 no 10 pp 1808ndash1812 2010

[83] M Walker K Iyer S Heaven and C J Banks ldquoAmmoniaremoval in anaerobic digestion by biogas stripping an evalu-ation of process alternatives using a first order rate model basedon experimental findingsrdquo Chemical Engineering Journal vol178 pp 138ndash145 2011

[84] C Zhang H Su and T Tan ldquoBatch and semi-continuousanaerobic digestion of foodwaste in a dual solidndashliquid systemrdquoBioresource Technology vol 145 pp 10ndash16 2013

[85] F Raposo V Fernandez-Cegrı M A de la Rubia et al ldquoBio-chemical methane potential (BMP) of solid organic substratesevaluation of anaerobic biodegradability using data from aninternational interlaboratory studyrdquo Journal of Chemical Tech-nology and Biotechnology vol 86 no 8 pp 1088ndash1098 2011

[86] P Jin S K Bhattacharya C J Williams and H Zhang ldquoEffectsof sulfide addition on copper inhibition in methanogenicsystemsrdquoWater Research vol 32 no 4 pp 977ndash988 1998

[87] A Schattauer E Abdoun P Weiland M Plochl and MHeiermann ldquoAbundance of trace elements in demonstrationbiogas plantsrdquo Biosystems Engineering vol 108 no 1 pp 57ndash652011

[88] V Facchin C Cavinato F Fatone P Pavan F Cecchi andD Bolzonella ldquoEffect of trace element supplementation on themesophilic anaerobic digestion of foodwaste in batch trials theinfluence of inoculum originrdquo Biochemical Engineering Journalvol 70 pp 71ndash77 2013

[89] C A Jackson-Moss J R Duncan and D R Cooper ldquoThe effectof calciumon anaerobic digestionrdquoBiotechnology Letters vol 11no 3 pp 219ndash224 1989

[90] H Q Yu J H Tay and H H P Fang ldquoThe roles of calciumin sludge granulation during UASB reactor start-uprdquo WaterResearch vol 35 no 4 pp 1052ndash1060 2001

[91] C-Y Lin and C-C Chen ldquoEffect of heavy metals on themethanogenic UASB granulerdquoWater Research vol 33 no 2 pp409ndash416 1999

[92] G Zayed and JWinter ldquoInhibition ofmethane production fromwhey by heavy metalsmdashprotective effect of sulfiderdquo AppliedMicrobiology andBiotechnology vol 53 no 6 pp 726ndash731 2000

[93] S Ghosh M P Henry and R W Christopher ldquoHemicelluloseconversion by anaerobic digestionrdquo Biomass vol 6 no 4 pp257ndash269 1985

[94] E Elbeshbishy G Nakhla andHHafez ldquoBiochemicalmethanepotential (BMP) of food waste and primary sludge influenceof inoculum pre-incubation and inoculum sourcerdquo BioresourceTechnology vol 110 pp 18ndash25 2012

[95] M S Lisboa and S Lansing ldquoCharacterizing food waste sub-strates for co-digestion through biochemical methane potential(BMP) experimentsrdquo Waste Management vol 33 no 12 pp2664ndash2669 2013

[96] M Murto L Bjornsson H Rosqvist and I Bohn ldquoEvaluatingthe biogas potential of the dry fraction from pretreatment offood waste from householdsrdquoWaste Management vol 33 no 5pp 1282ndash1289 2013

[97] J Marin K J Kennedy and C Eskicioglu ldquoEffect of microwaveirradiation on anaerobic degradability of model kitchen wasterdquoWaste Management vol 30 no 10 pp 1772ndash1779 2010

[98] K Izumi Y K Okishio C Niwa S Yamamoto and T TodaldquoEffects of particle size on anaerobic digestion of food wasterdquoInternational Journal of Bio-Deterioration Biodegradation vol64 no 7 pp 601ndash608 2010

[99] J Ma T H Duong M Smits W Verstraete and M CarballaldquoEnhanced biomethanation of kitchen waste by different pre-treatmentsrdquo Bioresource Technology vol 102 no 2 pp 592ndash5992011

[100] J-Y Wang X-Y Liu J C M Kao and O Stabnikova ldquoDiges-tion of pre-treated food waste in a hybrid anaerobic solid-liquid (HASL) systemrdquo Journal of Chemical Technology andBiotechnology vol 81 no 3 pp 345ndash351 2006

[101] O Stabnikova X Y Liu and J Y Wang ldquoDigestion offrozenthawed food waste in the hybrid anaerobic solid-liquidsystemrdquoWaste Management vol 28 no 9 pp 1654ndash1659 2008

[102] X Liu W Wang X Gao Y Zhou and R Shen ldquoEffect ofthermal pretreatment on the physical and chemical propertiesof municipal biomass wasterdquoWaste Management vol 32 no 2pp 249ndash255 2012

[103] SWKim J Y Park J K Kim et al ldquoDevelopment of amodifiedthree-stage methane production process using food wastesrdquoApplied Biochemistry and Biotechnology vol 84ndash86 pp 731ndash7412000

[104] J W Lim and J-Y Wang ldquoEnhanced hydrolysis and methaneyield by applying microaeration pretreatment to the anaerobicco-digestion of brown water and food wasterdquo Waste Manage-ment vol 33 no 4 pp 813ndash819 2013

BioMed Research International 17

[105] L Neves R Oliveira and M M Alves ldquoCo-digestion of cowmanure food waste and intermittent input of fatrdquo BioresourceTechnology vol 100 no 6 pp 1957ndash1962 2009

[106] S G Kim ldquoSystem for separation of oil and sludge from foodwaste leachaterdquo Korea Patent 10-2010-0053719

[107] C-F Chu Y-Y Li K-Q Xu Y Ebie Y Inamori and H-NKong ldquoA pH- and temperature-phased two-stage process forhydrogen and methane production from food wasterdquo Interna-tional Journal of Hydrogen Energy vol 33 no 18 pp 4739ndash47462008

[108] JMassanet-Nicolau R Dinsdale A Guwy andG Shipley ldquoUseof real time gas production data for more accurate comparisonof continuous single-stage and two-stage fermentationrdquo Biore-source Technology vol 129 pp 561ndash567 2013

[109] Y Koike M-Z An Y-Q Tang et al ldquoProduction of fuelethanol andmethane from garbage by high-efficiency two-stagefermentation processrdquo Journal of Bioscience and Bioengineeringvol 108 no 6 pp 508ndash512 2009

[110] X Hai-LouW Jing-Yuan and T Joo-Hwa ldquoA hybrid anaerobicsolid-liquid bioreactor for food waste digestionrdquo BiotechnologyLetters vol 24 no 10 pp 757ndash761 2002

[111] Y Li S Y Park and J Zhu ldquoSolid-state anaerobic digestionfor methane production from organic wasterdquo Renewable andSustainable Energy Reviews vol 15 no 1 pp 821ndash826 2011

[112] L Appels J Baeyens J Degreve and R Dewil ldquoPrinciples andpotential of the anaerobic digestion of waste-activated sludgerdquoProgress in Energy and Combustion Science vol 34 no 6 pp755ndash781 2008

[113] O P Karthikeyan and C Visvanathan ldquoBio-energy recoveryfrom high-solid organic substrates by dry anaerobic bio-conversion processes a reviewrdquo Reviews in EnvironmentalScience and BioTechnology vol 12 no 3 pp 257ndash284 2013

[114] J Guendouz P Buffiere J CachoMCarrere and J-PDelgenesldquoDry anaerobic digestion in batch mode design and operationof a laboratory-scale completelymixed reactorrdquoWasteManage-ment vol 30 no 10 pp 1768ndash1771 2010

[115] L Yang F Xu X Ge and Y Li ldquoChallenges and strategiesfor solid-state anaerobic digestion of lignocellulosic biomassrdquoRenewable and Sustainable Energy Reviews vol 44 pp 824ndash8342015

[116] A Abbassi-Guendouz E Trably J Hamelin et al ldquoMicro-bial community signature of high-solid content methanogenicecosystemsrdquo Bioresource Technology vol 133 pp 256ndash262 2013

[117] J Lindmark E Thorin R Bel Fdhila and E Dahlquis ldquoProb-lems and possibilities with the implementation of simulationand modeling at a biogas plantrdquo in Proceedings of the Interna-tional Conference on Applied Energy (ICAE rsquo12) Suzhou ChinaJuly 2012

[118] I Angelidaki L Ellegaard and B K Ahring ldquoA mathematicalmodel for dynamic simulation of anaerobic digestion of com-plex substrates focusing on ammonia inhibitionrdquoBiotechnologyand Bioengineering vol 42 no 2 pp 159ndash166 1993

[119] S Kalyuzhnyi A Veeken and B Hamelers ldquoTwo-particlemodel of anaerobic solid state fermentationrdquoWater Science andTechnology vol 41 no 3 pp 43ndash50 2000

[120] D J Martin L G A Potts and V A Heslop ldquoReactionmechanisms in solid-state anaerobic digestion I The reactionfront hypothesisrdquo Process Safety and Environmental Protectionvol 81 no 3 pp 171ndash179 2003

[121] D J Martin ldquoA novel mathematical model of solid-statedigestionrdquo Biotechnology Letters vol 22 no 1 pp 91ndash94 2000

[122] V A Vavilin M Y Shchelkanov and S V Rytov ldquoEffect of masstransfer on concentration wave propagation during anaerobicdigestion of solidwasterdquoWater Research vol 36 no 9 pp 2405ndash2409 2002

[123] V A Vavilin L Y Lokshina J P Y Jokela and J A RintalaldquoModeling solid waste decompositionrdquo Bioresource Technologyvol 94 no 1 pp 69ndash81 2004

[124] V A Vavilin S V Rytov L Y Lokshina S G Pavlostathisand M A Barlaz ldquoDistributed model of solid waste anaerobicdigestion effects of leachate recirculation and pH adjustmentrdquoBiotechnology and Bioengineering vol 81 no 1 pp 66ndash73 2003

[125] V A Vavilin and I Angelidaki ldquoAnaerobic degradation of solidmaterial importance of initiation centers for methanogenesismixing intensity and 2D distributed modelrdquo Biotechnology andBioengineering vol 89 no 1 pp 113ndash122 2005

[126] V A Vavilin L Y Lokshina X Flotats and I AngelidakildquoAnaerobic digestion of solid material multidimensional mod-eling of continuous-flow reactor with non-uniform influentconcentration distributionsrdquo Biotechnology and Bioengineeringvol 97 no 2 pp 354ndash366 2007

[127] H J Eber ldquoSimulation of chemical reaction fronts in anaerobicdigestion of solid wasterdquo in Proceedings of the ComputationalScience and Its Applications (ICCSA rsquo03) pp 503ndash512 MontrealCanada May 2003

[128] H J Eberl ldquoThe role of spatio-temporal effects in anaerobicdigestion of solid wasterdquo Nonlinear Analysis Theory Methodsamp Applications vol 63 no 5ndash7 pp e1497ndashe1505 2005

[129] A Abbassi-Guendouz D Brockmann E Trably et al ldquoTotalsolids content drives high solid anaerobic digestion via masstransfer limitationrdquo Bioresource Technology vol 111 pp 55ndash612012

[130] J Bollon R Le-Hyaric H Benbelkacem and P BuffiereldquoDevelopment of a kinetic model for anaerobic dry digestionprocesses focus on acetate degradation and moisture contentrdquoBiochemical Engineering Journal vol 56 no 3 pp 212ndash218 2011

[131] F Liotta P Chatellier G Esposito et al ldquoModified AnaerobicDigestionModel No1 for dry and semi-dry anaerobic digestionof solid organic wasterdquo Environmental Technology vol 36 no5ndash8 pp 870ndash880 2015

[132] F Xu Z-W Wang L Tang and Y Li ldquoA mass diffusion-basedinterpretation of the effect of total solids content on solid-state anaerobic digestion of cellulosic biomassrdquo BioresourceTechnology vol 167 pp 178ndash185 2014

[133] S Pommier D Chenu M Quintard and X Lefebvre ldquoAlogistic model for the prediction of the influence of water onthe solid waste methanization in landfillsrdquo Biotechnology andBioengineering vol 97 no 3 pp 473ndash482 2007

[134] L A Fdez-Guelfo C Alvarez-Gallego D Sales and L IRomero Garcıa ldquoDry-thermophilic anaerobic digestion oforganic fraction of municipal solid waste methane productionmodelingrdquoWasteManagement vol 32 no 3 pp 382ndash388 2012

[135] J Fernandez M Perez and L I Romero ldquoKinetics ofmesophilic anaerobic digestion of the organic fraction ofmunicipal solid waste influence of initial total solid concen-trationrdquo Bioresource Technology vol 101 no 16 pp 6322ndash63282010

[136] L N Liew J Shi and Y Li ldquoMethane production from solid-state anaerobic digestion of lignocellulosic biomassrdquo Biomassand Bioenergy vol 46 pp 125ndash132 2012

[137] D Brown J Shi and Y Li ldquoComparison of solid-state to liquidanaerobic digestion of lignocellulosic feedstocks for biogasproductionrdquo Bioresource Technology vol 124 pp 379ndash386 2012

18 BioMed Research International

[138] X Tong L H Smith and P LMcCarty ldquoMethane fermentationof selected lignocellulosic materialsrdquo Biomass vol 21 no 4 pp239ndash255 1990

[139] J-C Motte R Escudie N Bernet J-P Delgenes J-P Steyerand C Dumas ldquoDynamic effect of total solid content low sub-strateinoculum ratio and particle size on solid-state anaerobicdigestionrdquo Bioresource Technology vol 144 pp 141ndash148 2013

[140] F Xu Z-W Wang and Y Li ldquoPredicting the methane yieldof lignocellulosic biomass in mesophilic solid-state anaerobicdigestion based on feedstock characteristics and process param-etersrdquo Bioresource Technology vol 173 pp 168ndash176 2014

[141] F Xu Y Li and Z-W Wang ldquoMathematical modeling of solid-state anaerobic digestionrdquo Progress in Energy and CombustionScience vol 51 pp 49ndash66 2015

[142] L Li Q He Y Ma X Wang and X Peng ldquoDynamicsof microbial community in a mesophilic anaerobic digestertreating food waste relationship between community structureand process stabilityrdquo Bioresource Technology vol 189 pp 113ndash120 2015

[143] J W Lim C-L Chen I J R Ho and J-Y Wang ldquoStudy ofmicrobial community and biodegradation efficiency for single-and two-phase anaerobic co-digestion of brown water and foodwasterdquo Bioresource Technology vol 147 pp 193ndash201 2013

[144] S-K Cho W-T Im D-H Kim M-H Kim H-S Shin and S-E Oh ldquoDry anaerobic digestion of foodwaste undermesophilicconditions performance and methanogenic community analy-sisrdquo Bioresource Technology vol 131 pp 210ndash217 2013

[145] S Wan L Sun J Sun and W Luo ldquoBiogas production andmicrobial community change during the Co-digestion of foodwaste with chinese silver grass in a single-stage anaerobicreactorrdquo Biotechnology and Bioprocess Engineering vol 18 no5 pp 1022ndash1030 2013

[146] L Li Q He Y Ma X Wang and X Peng ldquoA mesophilicanaerobic digester for treating food waste process stability andmicrobial community analysis using pyrosequencingrdquo Micro-bial Cell Factories vol 15 no 1 article no 65 2016

[147] M Zamanzadeh L H Hagen K Svensson R Linjordet and SJ Horn ldquoAnaerobic digestion of food wastemdasheffect of recircula-tion and temperature on performance andmicrobiologyrdquoWaterResearch vol 96 pp 246ndash254 2016

[148] M Gulhane P Pandit A Khardenavis and D Singh ldquoStudyof microbial community plasticity for anaerobic digestionof vegetable waste in Anaerobic Baffled Reactorrdquo RenewableEnergy vol 96 pp 246ndash254 2016

[149] X Guo C Wang F Sun W Zhu and W Wu ldquoA comparisonof microbial characteristics between the thermophilic andmesophilic anaerobic digesters exposed to elevated food wasteloadingsrdquo Bioresource Technology vol 152 pp 420ndash428 2014

[150] F Ali Shah Q Mahmood M Maroof Shah A Pervez and SAhmadAsad ldquoMicrobial ecology of anaerobic digesters the keyplayers of anaerobiosisrdquo The Scientific World Journal vol 2014Article ID 183752 21 pages 2014

[151] H Bouallagui M Torrijos J J Godon et al ldquoMicrobial mon-itoring by molecular tools of a two-phase anaerobic bioreactortreating fruit and vegetable wastesrdquo Biotechnology Letters vol26 no 10 pp 857ndash862 2004

[152] L Manoharan S K Kushwaha K Hedlund and D AhrenldquoCaptured metagenomics large-scale targeting of genes basedon rsquosequence capturersquo reveals functional diversity in soilsrdquoDNAResearch vol 22 no 6 pp 451ndash460 2015

[153] H Sanguin B Remenant A Dechesne et al ldquoPotential ofa 16S rRNA-based taxonomic microarray for analyzing the

rhizosphere effects ofmaize onAgrobacteriumspp and bacterialcommunitiesrdquoApplied and EnvironmentalMicrobiology vol 72no 6 pp 4302ndash4312 2006

[154] H Sanguin A Herrera C Oger-Desfeux et al ldquoDevelopmentand validation of a prototype 16S rRNA-based taxonomicmicroarray for Alphaproteobacteriardquo Environmental Microbiol-ogy vol 8 no 2 pp 289ndash307 2006

[155] M Kyselkova J Kopecky T Felfoldi et al ldquoDevelopment of a16S rRNA gene-based prototype microarray for the detection ofselected actinomycetes generardquo International Journal of Generaland Molecular Microbiology vol 94 no 3 pp 439ndash453 2008

[156] W-T Liu A D Mirzabekov and D A Stahl ldquoOptimization ofan oligonucleotide microchip for microbial identification stud-ies a non-equilibrium dissociation approachrdquo EnvironmentalMicrobiology vol 3 no 10 pp 619ndash629 2001

[157] S Schonmann A Loy C Wimmersberger et al ldquo16S rRNAgene-based phylogenetic microarray for simultaneous identifi-cation of members of the genus Burkholderiardquo EnvironmentalMicrobiology vol 11 no 4 pp 779ndash800 2009

[158] A E Warsen M J Krug S LaFrentz D R Stanek F JLoge and D R Call ldquoSimultaneous discrimination between15 fish pathogens by using 16S ribosomal DNA PCR and DNAmicroarraysrdquo Applied and Environmental Microbiology vol 70no 7 pp 4216ndash4221 2004

[159] I H Franke-Whittle S H Klammer and H Insam ldquoDesignand application of an oligonucleotide microarray for theinvestigation of compost microbial communitiesrdquo Journal ofMicrobiological Methods vol 62 no 1 pp 37ndash56 2005

[160] J Peplies C Lachmund F O Glockner and W Manz ldquoADNA microarray platform based on direct detection of rRNAfor characterization of freshwater sediment-related prokaryoticcommunitiesrdquoApplied and EnvironmentalMicrobiology vol 72no 7 pp 4829ndash4838 2006

[161] S Demaneche H Sanguin J Pote et al ldquoAntibiotic-resistantsoil bacteria in transgenic plant fieldsrdquo Proceedings of theNational Academy of Sciences of the United States of Americavol 105 no 10 pp 3957ndash3962 2008

[162] A Loy A Lehner N Lee et al ldquoOligonucleotide microarrayfor 16S rRNA gene-based detection of all recognized lineagesof sulfate-reducing prokaryotes in the environmentrdquo Appliedand Environmental Microbiology vol 68 no 10 pp 5064ndash50812002

[163] S Siripong J J Kelly D A Stahl and B E Rittmann ldquoImpactof prehybridization PCR amplification onmicroarray detectionof nitrifying bacteria in wastewater treatment plant samplesrdquoEnvironmental Microbiology vol 8 no 9 pp 1564ndash1574 2006

[164] S K Kushwaha L Manoharan T Meerupati K Hedlundand D Ahren ldquoErratum to MetCap a bioinformatics probedesign pipeline for large-scale targeted metagenomicsrdquo BMCBioinformatics vol 17 article 39 2016

[165] httpswwwilluminacomtechnologynext-generation-sequen-cingsequencing-technologyhtml

[166] httpswwwthermofishercominenhomelife-sciencesequen-cingnext-generation-sequencingion-torrent-next-generation-sequencing-workflowion-torrent-next-generation-sequencing-run-sequenceion-proton-system-for-next-generation-sequen-cinghtml

[167] httpwwwpacbcomproducts-and-servicespacbio-systemsrsii

[168] F J Azuaje M Heymann A-M Ternes et al ldquoBioinformaticsas a driver not a passenger of translational biomedical research

BioMed Research International 17

[105] L Neves R Oliveira and M M Alves ldquoCo-digestion of cowmanure food waste and intermittent input of fatrdquo BioresourceTechnology vol 100 no 6 pp 1957ndash1962 2009

[106] S G Kim ldquoSystem for separation of oil and sludge from foodwaste leachaterdquo Korea Patent 10-2010-0053719

[107] C-F Chu Y-Y Li K-Q Xu Y Ebie Y Inamori and H-NKong ldquoA pH- and temperature-phased two-stage process forhydrogen and methane production from food wasterdquo Interna-tional Journal of Hydrogen Energy vol 33 no 18 pp 4739ndash47462008

[108] JMassanet-Nicolau R Dinsdale A Guwy andG Shipley ldquoUseof real time gas production data for more accurate comparisonof continuous single-stage and two-stage fermentationrdquo Biore-source Technology vol 129 pp 561ndash567 2013

[109] Y Koike M-Z An Y-Q Tang et al ldquoProduction of fuelethanol andmethane from garbage by high-efficiency two-stagefermentation processrdquo Journal of Bioscience and Bioengineeringvol 108 no 6 pp 508ndash512 2009

[110] X Hai-LouW Jing-Yuan and T Joo-Hwa ldquoA hybrid anaerobicsolid-liquid bioreactor for food waste digestionrdquo BiotechnologyLetters vol 24 no 10 pp 757ndash761 2002

[111] Y Li S Y Park and J Zhu ldquoSolid-state anaerobic digestionfor methane production from organic wasterdquo Renewable andSustainable Energy Reviews vol 15 no 1 pp 821ndash826 2011

[112] L Appels J Baeyens J Degreve and R Dewil ldquoPrinciples andpotential of the anaerobic digestion of waste-activated sludgerdquoProgress in Energy and Combustion Science vol 34 no 6 pp755ndash781 2008

[113] O P Karthikeyan and C Visvanathan ldquoBio-energy recoveryfrom high-solid organic substrates by dry anaerobic bio-conversion processes a reviewrdquo Reviews in EnvironmentalScience and BioTechnology vol 12 no 3 pp 257ndash284 2013

[114] J Guendouz P Buffiere J CachoMCarrere and J-PDelgenesldquoDry anaerobic digestion in batch mode design and operationof a laboratory-scale completelymixed reactorrdquoWasteManage-ment vol 30 no 10 pp 1768ndash1771 2010

[115] L Yang F Xu X Ge and Y Li ldquoChallenges and strategiesfor solid-state anaerobic digestion of lignocellulosic biomassrdquoRenewable and Sustainable Energy Reviews vol 44 pp 824ndash8342015

[116] A Abbassi-Guendouz E Trably J Hamelin et al ldquoMicro-bial community signature of high-solid content methanogenicecosystemsrdquo Bioresource Technology vol 133 pp 256ndash262 2013

[117] J Lindmark E Thorin R Bel Fdhila and E Dahlquis ldquoProb-lems and possibilities with the implementation of simulationand modeling at a biogas plantrdquo in Proceedings of the Interna-tional Conference on Applied Energy (ICAE rsquo12) Suzhou ChinaJuly 2012

[118] I Angelidaki L Ellegaard and B K Ahring ldquoA mathematicalmodel for dynamic simulation of anaerobic digestion of com-plex substrates focusing on ammonia inhibitionrdquoBiotechnologyand Bioengineering vol 42 no 2 pp 159ndash166 1993

[119] S Kalyuzhnyi A Veeken and B Hamelers ldquoTwo-particlemodel of anaerobic solid state fermentationrdquoWater Science andTechnology vol 41 no 3 pp 43ndash50 2000

[120] D J Martin L G A Potts and V A Heslop ldquoReactionmechanisms in solid-state anaerobic digestion I The reactionfront hypothesisrdquo Process Safety and Environmental Protectionvol 81 no 3 pp 171ndash179 2003

[121] D J Martin ldquoA novel mathematical model of solid-statedigestionrdquo Biotechnology Letters vol 22 no 1 pp 91ndash94 2000

[122] V A Vavilin M Y Shchelkanov and S V Rytov ldquoEffect of masstransfer on concentration wave propagation during anaerobicdigestion of solidwasterdquoWater Research vol 36 no 9 pp 2405ndash2409 2002

[123] V A Vavilin L Y Lokshina J P Y Jokela and J A RintalaldquoModeling solid waste decompositionrdquo Bioresource Technologyvol 94 no 1 pp 69ndash81 2004

[124] V A Vavilin S V Rytov L Y Lokshina S G Pavlostathisand M A Barlaz ldquoDistributed model of solid waste anaerobicdigestion effects of leachate recirculation and pH adjustmentrdquoBiotechnology and Bioengineering vol 81 no 1 pp 66ndash73 2003

[125] V A Vavilin and I Angelidaki ldquoAnaerobic degradation of solidmaterial importance of initiation centers for methanogenesismixing intensity and 2D distributed modelrdquo Biotechnology andBioengineering vol 89 no 1 pp 113ndash122 2005

[126] V A Vavilin L Y Lokshina X Flotats and I AngelidakildquoAnaerobic digestion of solid material multidimensional mod-eling of continuous-flow reactor with non-uniform influentconcentration distributionsrdquo Biotechnology and Bioengineeringvol 97 no 2 pp 354ndash366 2007

[127] H J Eber ldquoSimulation of chemical reaction fronts in anaerobicdigestion of solid wasterdquo in Proceedings of the ComputationalScience and Its Applications (ICCSA rsquo03) pp 503ndash512 MontrealCanada May 2003

[128] H J Eberl ldquoThe role of spatio-temporal effects in anaerobicdigestion of solid wasterdquo Nonlinear Analysis Theory Methodsamp Applications vol 63 no 5ndash7 pp e1497ndashe1505 2005

[129] A Abbassi-Guendouz D Brockmann E Trably et al ldquoTotalsolids content drives high solid anaerobic digestion via masstransfer limitationrdquo Bioresource Technology vol 111 pp 55ndash612012

[130] J Bollon R Le-Hyaric H Benbelkacem and P BuffiereldquoDevelopment of a kinetic model for anaerobic dry digestionprocesses focus on acetate degradation and moisture contentrdquoBiochemical Engineering Journal vol 56 no 3 pp 212ndash218 2011

[131] F Liotta P Chatellier G Esposito et al ldquoModified AnaerobicDigestionModel No1 for dry and semi-dry anaerobic digestionof solid organic wasterdquo Environmental Technology vol 36 no5ndash8 pp 870ndash880 2015

[132] F Xu Z-W Wang L Tang and Y Li ldquoA mass diffusion-basedinterpretation of the effect of total solids content on solid-state anaerobic digestion of cellulosic biomassrdquo BioresourceTechnology vol 167 pp 178ndash185 2014

[133] S Pommier D Chenu M Quintard and X Lefebvre ldquoAlogistic model for the prediction of the influence of water onthe solid waste methanization in landfillsrdquo Biotechnology andBioengineering vol 97 no 3 pp 473ndash482 2007

[134] L A Fdez-Guelfo C Alvarez-Gallego D Sales and L IRomero Garcıa ldquoDry-thermophilic anaerobic digestion oforganic fraction of municipal solid waste methane productionmodelingrdquoWasteManagement vol 32 no 3 pp 382ndash388 2012

[135] J Fernandez M Perez and L I Romero ldquoKinetics ofmesophilic anaerobic digestion of the organic fraction ofmunicipal solid waste influence of initial total solid concen-trationrdquo Bioresource Technology vol 101 no 16 pp 6322ndash63282010

[136] L N Liew J Shi and Y Li ldquoMethane production from solid-state anaerobic digestion of lignocellulosic biomassrdquo Biomassand Bioenergy vol 46 pp 125ndash132 2012

[137] D Brown J Shi and Y Li ldquoComparison of solid-state to liquidanaerobic digestion of lignocellulosic feedstocks for biogasproductionrdquo Bioresource Technology vol 124 pp 379ndash386 2012

18 BioMed Research International

[138] X Tong L H Smith and P LMcCarty ldquoMethane fermentationof selected lignocellulosic materialsrdquo Biomass vol 21 no 4 pp239ndash255 1990

[139] J-C Motte R Escudie N Bernet J-P Delgenes J-P Steyerand C Dumas ldquoDynamic effect of total solid content low sub-strateinoculum ratio and particle size on solid-state anaerobicdigestionrdquo Bioresource Technology vol 144 pp 141ndash148 2013

[140] F Xu Z-W Wang and Y Li ldquoPredicting the methane yieldof lignocellulosic biomass in mesophilic solid-state anaerobicdigestion based on feedstock characteristics and process param-etersrdquo Bioresource Technology vol 173 pp 168ndash176 2014

[141] F Xu Y Li and Z-W Wang ldquoMathematical modeling of solid-state anaerobic digestionrdquo Progress in Energy and CombustionScience vol 51 pp 49ndash66 2015

[142] L Li Q He Y Ma X Wang and X Peng ldquoDynamicsof microbial community in a mesophilic anaerobic digestertreating food waste relationship between community structureand process stabilityrdquo Bioresource Technology vol 189 pp 113ndash120 2015

[143] J W Lim C-L Chen I J R Ho and J-Y Wang ldquoStudy ofmicrobial community and biodegradation efficiency for single-and two-phase anaerobic co-digestion of brown water and foodwasterdquo Bioresource Technology vol 147 pp 193ndash201 2013

[144] S-K Cho W-T Im D-H Kim M-H Kim H-S Shin and S-E Oh ldquoDry anaerobic digestion of foodwaste undermesophilicconditions performance and methanogenic community analy-sisrdquo Bioresource Technology vol 131 pp 210ndash217 2013

[145] S Wan L Sun J Sun and W Luo ldquoBiogas production andmicrobial community change during the Co-digestion of foodwaste with chinese silver grass in a single-stage anaerobicreactorrdquo Biotechnology and Bioprocess Engineering vol 18 no5 pp 1022ndash1030 2013

[146] L Li Q He Y Ma X Wang and X Peng ldquoA mesophilicanaerobic digester for treating food waste process stability andmicrobial community analysis using pyrosequencingrdquo Micro-bial Cell Factories vol 15 no 1 article no 65 2016

[147] M Zamanzadeh L H Hagen K Svensson R Linjordet and SJ Horn ldquoAnaerobic digestion of food wastemdasheffect of recircula-tion and temperature on performance andmicrobiologyrdquoWaterResearch vol 96 pp 246ndash254 2016

[148] M Gulhane P Pandit A Khardenavis and D Singh ldquoStudyof microbial community plasticity for anaerobic digestionof vegetable waste in Anaerobic Baffled Reactorrdquo RenewableEnergy vol 96 pp 246ndash254 2016

[149] X Guo C Wang F Sun W Zhu and W Wu ldquoA comparisonof microbial characteristics between the thermophilic andmesophilic anaerobic digesters exposed to elevated food wasteloadingsrdquo Bioresource Technology vol 152 pp 420ndash428 2014

[150] F Ali Shah Q Mahmood M Maroof Shah A Pervez and SAhmadAsad ldquoMicrobial ecology of anaerobic digesters the keyplayers of anaerobiosisrdquo The Scientific World Journal vol 2014Article ID 183752 21 pages 2014

[151] H Bouallagui M Torrijos J J Godon et al ldquoMicrobial mon-itoring by molecular tools of a two-phase anaerobic bioreactortreating fruit and vegetable wastesrdquo Biotechnology Letters vol26 no 10 pp 857ndash862 2004

[152] L Manoharan S K Kushwaha K Hedlund and D AhrenldquoCaptured metagenomics large-scale targeting of genes basedon rsquosequence capturersquo reveals functional diversity in soilsrdquoDNAResearch vol 22 no 6 pp 451ndash460 2015

[153] H Sanguin B Remenant A Dechesne et al ldquoPotential ofa 16S rRNA-based taxonomic microarray for analyzing the

rhizosphere effects ofmaize onAgrobacteriumspp and bacterialcommunitiesrdquoApplied and EnvironmentalMicrobiology vol 72no 6 pp 4302ndash4312 2006

[154] H Sanguin A Herrera C Oger-Desfeux et al ldquoDevelopmentand validation of a prototype 16S rRNA-based taxonomicmicroarray for Alphaproteobacteriardquo Environmental Microbiol-ogy vol 8 no 2 pp 289ndash307 2006

[155] M Kyselkova J Kopecky T Felfoldi et al ldquoDevelopment of a16S rRNA gene-based prototype microarray for the detection ofselected actinomycetes generardquo International Journal of Generaland Molecular Microbiology vol 94 no 3 pp 439ndash453 2008

[156] W-T Liu A D Mirzabekov and D A Stahl ldquoOptimization ofan oligonucleotide microchip for microbial identification stud-ies a non-equilibrium dissociation approachrdquo EnvironmentalMicrobiology vol 3 no 10 pp 619ndash629 2001

[157] S Schonmann A Loy C Wimmersberger et al ldquo16S rRNAgene-based phylogenetic microarray for simultaneous identifi-cation of members of the genus Burkholderiardquo EnvironmentalMicrobiology vol 11 no 4 pp 779ndash800 2009

[158] A E Warsen M J Krug S LaFrentz D R Stanek F JLoge and D R Call ldquoSimultaneous discrimination between15 fish pathogens by using 16S ribosomal DNA PCR and DNAmicroarraysrdquo Applied and Environmental Microbiology vol 70no 7 pp 4216ndash4221 2004

[159] I H Franke-Whittle S H Klammer and H Insam ldquoDesignand application of an oligonucleotide microarray for theinvestigation of compost microbial communitiesrdquo Journal ofMicrobiological Methods vol 62 no 1 pp 37ndash56 2005

[160] J Peplies C Lachmund F O Glockner and W Manz ldquoADNA microarray platform based on direct detection of rRNAfor characterization of freshwater sediment-related prokaryoticcommunitiesrdquoApplied and EnvironmentalMicrobiology vol 72no 7 pp 4829ndash4838 2006

[161] S Demaneche H Sanguin J Pote et al ldquoAntibiotic-resistantsoil bacteria in transgenic plant fieldsrdquo Proceedings of theNational Academy of Sciences of the United States of Americavol 105 no 10 pp 3957ndash3962 2008

[162] A Loy A Lehner N Lee et al ldquoOligonucleotide microarrayfor 16S rRNA gene-based detection of all recognized lineagesof sulfate-reducing prokaryotes in the environmentrdquo Appliedand Environmental Microbiology vol 68 no 10 pp 5064ndash50812002

[163] S Siripong J J Kelly D A Stahl and B E Rittmann ldquoImpactof prehybridization PCR amplification onmicroarray detectionof nitrifying bacteria in wastewater treatment plant samplesrdquoEnvironmental Microbiology vol 8 no 9 pp 1564ndash1574 2006

[164] S K Kushwaha L Manoharan T Meerupati K Hedlundand D Ahren ldquoErratum to MetCap a bioinformatics probedesign pipeline for large-scale targeted metagenomicsrdquo BMCBioinformatics vol 17 article 39 2016

[165] httpswwwilluminacomtechnologynext-generation-sequen-cingsequencing-technologyhtml

[166] httpswwwthermofishercominenhomelife-sciencesequen-cingnext-generation-sequencingion-torrent-next-generation-sequencing-workflowion-torrent-next-generation-sequencing-run-sequenceion-proton-system-for-next-generation-sequen-cinghtml

[167] httpwwwpacbcomproducts-and-servicespacbio-systemsrsii

[168] F J Azuaje M Heymann A-M Ternes et al ldquoBioinformaticsas a driver not a passenger of translational biomedical research

18 BioMed Research International

[138] X Tong L H Smith and P LMcCarty ldquoMethane fermentationof selected lignocellulosic materialsrdquo Biomass vol 21 no 4 pp239ndash255 1990

[139] J-C Motte R Escudie N Bernet J-P Delgenes J-P Steyerand C Dumas ldquoDynamic effect of total solid content low sub-strateinoculum ratio and particle size on solid-state anaerobicdigestionrdquo Bioresource Technology vol 144 pp 141ndash148 2013

[140] F Xu Z-W Wang and Y Li ldquoPredicting the methane yieldof lignocellulosic biomass in mesophilic solid-state anaerobicdigestion based on feedstock characteristics and process param-etersrdquo Bioresource Technology vol 173 pp 168ndash176 2014

[141] F Xu Y Li and Z-W Wang ldquoMathematical modeling of solid-state anaerobic digestionrdquo Progress in Energy and CombustionScience vol 51 pp 49ndash66 2015

[142] L Li Q He Y Ma X Wang and X Peng ldquoDynamicsof microbial community in a mesophilic anaerobic digestertreating food waste relationship between community structureand process stabilityrdquo Bioresource Technology vol 189 pp 113ndash120 2015

[143] J W Lim C-L Chen I J R Ho and J-Y Wang ldquoStudy ofmicrobial community and biodegradation efficiency for single-and two-phase anaerobic co-digestion of brown water and foodwasterdquo Bioresource Technology vol 147 pp 193ndash201 2013

[144] S-K Cho W-T Im D-H Kim M-H Kim H-S Shin and S-E Oh ldquoDry anaerobic digestion of foodwaste undermesophilicconditions performance and methanogenic community analy-sisrdquo Bioresource Technology vol 131 pp 210ndash217 2013

[145] S Wan L Sun J Sun and W Luo ldquoBiogas production andmicrobial community change during the Co-digestion of foodwaste with chinese silver grass in a single-stage anaerobicreactorrdquo Biotechnology and Bioprocess Engineering vol 18 no5 pp 1022ndash1030 2013

[146] L Li Q He Y Ma X Wang and X Peng ldquoA mesophilicanaerobic digester for treating food waste process stability andmicrobial community analysis using pyrosequencingrdquo Micro-bial Cell Factories vol 15 no 1 article no 65 2016

[147] M Zamanzadeh L H Hagen K Svensson R Linjordet and SJ Horn ldquoAnaerobic digestion of food wastemdasheffect of recircula-tion and temperature on performance andmicrobiologyrdquoWaterResearch vol 96 pp 246ndash254 2016

[148] M Gulhane P Pandit A Khardenavis and D Singh ldquoStudyof microbial community plasticity for anaerobic digestionof vegetable waste in Anaerobic Baffled Reactorrdquo RenewableEnergy vol 96 pp 246ndash254 2016

[149] X Guo C Wang F Sun W Zhu and W Wu ldquoA comparisonof microbial characteristics between the thermophilic andmesophilic anaerobic digesters exposed to elevated food wasteloadingsrdquo Bioresource Technology vol 152 pp 420ndash428 2014

[150] F Ali Shah Q Mahmood M Maroof Shah A Pervez and SAhmadAsad ldquoMicrobial ecology of anaerobic digesters the keyplayers of anaerobiosisrdquo The Scientific World Journal vol 2014Article ID 183752 21 pages 2014

[151] H Bouallagui M Torrijos J J Godon et al ldquoMicrobial mon-itoring by molecular tools of a two-phase anaerobic bioreactortreating fruit and vegetable wastesrdquo Biotechnology Letters vol26 no 10 pp 857ndash862 2004

[152] L Manoharan S K Kushwaha K Hedlund and D AhrenldquoCaptured metagenomics large-scale targeting of genes basedon rsquosequence capturersquo reveals functional diversity in soilsrdquoDNAResearch vol 22 no 6 pp 451ndash460 2015

[153] H Sanguin B Remenant A Dechesne et al ldquoPotential ofa 16S rRNA-based taxonomic microarray for analyzing the

rhizosphere effects ofmaize onAgrobacteriumspp and bacterialcommunitiesrdquoApplied and EnvironmentalMicrobiology vol 72no 6 pp 4302ndash4312 2006

[154] H Sanguin A Herrera C Oger-Desfeux et al ldquoDevelopmentand validation of a prototype 16S rRNA-based taxonomicmicroarray for Alphaproteobacteriardquo Environmental Microbiol-ogy vol 8 no 2 pp 289ndash307 2006

[155] M Kyselkova J Kopecky T Felfoldi et al ldquoDevelopment of a16S rRNA gene-based prototype microarray for the detection ofselected actinomycetes generardquo International Journal of Generaland Molecular Microbiology vol 94 no 3 pp 439ndash453 2008

[156] W-T Liu A D Mirzabekov and D A Stahl ldquoOptimization ofan oligonucleotide microchip for microbial identification stud-ies a non-equilibrium dissociation approachrdquo EnvironmentalMicrobiology vol 3 no 10 pp 619ndash629 2001

[157] S Schonmann A Loy C Wimmersberger et al ldquo16S rRNAgene-based phylogenetic microarray for simultaneous identifi-cation of members of the genus Burkholderiardquo EnvironmentalMicrobiology vol 11 no 4 pp 779ndash800 2009

[158] A E Warsen M J Krug S LaFrentz D R Stanek F JLoge and D R Call ldquoSimultaneous discrimination between15 fish pathogens by using 16S ribosomal DNA PCR and DNAmicroarraysrdquo Applied and Environmental Microbiology vol 70no 7 pp 4216ndash4221 2004

[159] I H Franke-Whittle S H Klammer and H Insam ldquoDesignand application of an oligonucleotide microarray for theinvestigation of compost microbial communitiesrdquo Journal ofMicrobiological Methods vol 62 no 1 pp 37ndash56 2005

[160] J Peplies C Lachmund F O Glockner and W Manz ldquoADNA microarray platform based on direct detection of rRNAfor characterization of freshwater sediment-related prokaryoticcommunitiesrdquoApplied and EnvironmentalMicrobiology vol 72no 7 pp 4829ndash4838 2006

[161] S Demaneche H Sanguin J Pote et al ldquoAntibiotic-resistantsoil bacteria in transgenic plant fieldsrdquo Proceedings of theNational Academy of Sciences of the United States of Americavol 105 no 10 pp 3957ndash3962 2008

[162] A Loy A Lehner N Lee et al ldquoOligonucleotide microarrayfor 16S rRNA gene-based detection of all recognized lineagesof sulfate-reducing prokaryotes in the environmentrdquo Appliedand Environmental Microbiology vol 68 no 10 pp 5064ndash50812002

[163] S Siripong J J Kelly D A Stahl and B E Rittmann ldquoImpactof prehybridization PCR amplification onmicroarray detectionof nitrifying bacteria in wastewater treatment plant samplesrdquoEnvironmental Microbiology vol 8 no 9 pp 1564ndash1574 2006

[164] S K Kushwaha L Manoharan T Meerupati K Hedlundand D Ahren ldquoErratum to MetCap a bioinformatics probedesign pipeline for large-scale targeted metagenomicsrdquo BMCBioinformatics vol 17 article 39 2016

[165] httpswwwilluminacomtechnologynext-generation-sequen-cingsequencing-technologyhtml

[166] httpswwwthermofishercominenhomelife-sciencesequen-cingnext-generation-sequencingion-torrent-next-generation-sequencing-workflowion-torrent-next-generation-sequencing-run-sequenceion-proton-system-for-next-generation-sequen-cinghtml

[167] httpwwwpacbcomproducts-and-servicespacbio-systemsrsii

[168] F J Azuaje M Heymann A-M Ternes et al ldquoBioinformaticsas a driver not a passenger of translational biomedical research

BioMed Research International 19

perspectives from the 6th Benelux bioinformatics conferencerdquoJournal of Clinical Bioinformatics vol 2 no 1 article no 7 2012

[169] P Hugenholtz ldquoExploring prokaryotic diversity in the genomicerardquo Genome Biology vol 3 no 2 pp 00031ndash00038 2002

[170] T Thomas J Gilbert and F Meyer ldquoMetagenomicsmdasha guidefrom sampling to data analysisrdquo Microbial Informatics andExperimentation vol 2 no 1 2012

[171] J A Gilbert F Meyer D Antonopoulos et al ldquoMeeting reportthe terabase metagenomics workshop and the vision of an earthmicrobiome projectrdquo Standards in Genomic Sciences vol 3 no3 pp 243ndash248 2010

[172] T O Delmont C Malandain E Prestat et al ldquoMetagenomicmining for microbiologistsrdquo ISME Journal vol 5 no 12 pp1837ndash1843 2011

[173] J A Gilbert F Meyer andM J Bailey ldquoThe Future of microbialmetagenomics (or is ignorance bliss)rdquoThe ISME Journal vol 5no 5 pp 777ndash779 2011

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anatomy Research International

PeptidesInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

International Journal of

Volume 2014

Zoology

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Molecular Biology International

GenomicsInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioinformaticsAdvances in

Marine BiologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Signal TransductionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

Evolutionary BiologyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Biochemistry Research International

ArchaeaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Genetics Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Virolog y

Hindawi Publishing Corporationhttpwwwhindawicom

Nucleic AcidsJournal of

Volume 2014

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Enzyme Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Microbiology

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anatomy Research International

PeptidesInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

International Journal of

Volume 2014

Zoology

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Molecular Biology International

GenomicsInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioinformaticsAdvances in

Marine BiologyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Signal TransductionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

BioMed Research International

Evolutionary BiologyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Biochemistry Research International

ArchaeaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Genetics Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Virolog y

Hindawi Publishing Corporationhttpwwwhindawicom

Nucleic AcidsJournal of

Volume 2014

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Enzyme Research

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

Microbiology