Energy Production and Compost Generation From a Segregated Municipal Waste Stream Using Bi-Phasic Anaerobic Digestion_My Paper

8/14/2019 Energy Production and Compost Generation From a Segregated Municipal Waste Stream Using Bi-Phasic Anaerobic

1/23

Energy Production and Compost Generation from a Segregated

Municipal Waste Stream Using Bi-phasic Anaerobic Digestion

H.W. Yu, Z. Samani, A. Hanson, G. Smith

New M exico State University

Las Cruces NM, 88001

United States of America

ABSTRACT

Municipal solid wastes are major sources of air, water and soil contamination. There is a

need for alternative waste management techniques to better utilize the waste andminimize its adverse environmental impact. A two-phase bio-fermentation system was

used to evaluate the feasibility of producing methane from high carbon segregated waste

from a major Citys municipal solid waste stream. The bi-phasic system consists of a

solid phase and a methane phase. Leachate is re-circulated through the solid phase until a

desired level of volatile fatty acid (VFA) is accumulated in the leachate. The leachate istransferred to the methane reactor where the VFA is converted to methane. The average

methane concentration in the produced gas was in excess of 71 percent. The material

remaining after the anaerobic stabilization was composted. The compost was sufficient

quality for use in agricultural app lication, and thus the research represented a full

beneficial reuse of the solid waste stream.

Innovative Uses of Biosolids

Copyright 2001 Water Environment Federation. All Rights Reserved. page


2/23

INTRODUCTION

The solid-state bi-phasic anaerobic fermentation process is a patented technology (Ghosh,

1982a, 1983,1987) that has advanced through bench- and small, pilot-scale research over

the last 20 years with support from the City and County of Milwaukee, Wisconsin Gas

Company , Rexnord, Inc., and Americology, Inc. (Ghosh, 1984, 1985a, 1985b, 1985c;

Ghosh and Lall, 1988); and the Department of Energy (Sun and Ghosh, 1992). However,

it is only recently that the design information needed for design of a large pilot

(prototype) plant has become available through work supported by the New Energy &

Industrial Organization (NEDO), Ministry of International Trade and Industry (MITI),

Government of Japan (Ghosh et al., 1997). This paper presents performance data for this

system developed operated at ambient temperature with a feedstock of

commercial/industrial waste simulating the waste stream available to the City of

Albuquerque NM .

Conventional anaerobic fermentation of chemically heterogeneous feeds is conducted in a

single-stage fermenter (called a "digester") to recover 50-60% of the feed organic carbon

as methane, a renewable biofuel. Several interdependent biochemical pathways mediated

by microbial groups of different p hysiology and genotypic characteristics are involved in

the overall conversion of organic solids to volatile fatty acids (VFAs), and finally to

methane. It is important to note that dilute feed recycle streams, with total solids (TS)

concentrations of about 5-wt %, is used to balance the processes of acids production from

solids (acidogenesis) and acid conversion to methane (methanogenesis). With

concentrated soluble or high-solids feeds streams often used in other processes, VFAs




3/23

production proceeds at a much faster rate than the rate of conversion of VFAs to methane

thereby causing acids accumulation, a pH drop, and the consequent inhibition of

methanogenesis (Ghosh et al., 1975; Ghosh, 1987, Longworth et. al., 1999). The

imbalance between the processes of acidogenesis and methanogenesis is averted by

physically isolating the two major microbial phases in two separate fermenters (Pohland

and Ghosh, 1971; Ghosh, S. and Klass, D. L., 1977; Ghosh, S., 1982; Ghosh, et al., 1987;

Alexiou et aL, 1994a,1994b; Ghosh et al., 1994). As described below and shown in

Figure 1, the two-phase process consists of an acid phase fermenter (solid phase reactor)

operated in tandem with a methanation or biogasification fermenter (gas production

phase). In the solid phase, water is applied from the top of the waste using a drip or

sprinkler irrigation system. The leachate is collected at the bottom of the solid phase

using an underdrain sump. The leachate is then re-circulated through the solid waste bed

until a desired level of VFAs is achieved in the leachate. At this point the leachate is

transferred to the methane production reactor where the VFAs are converted to methane

in a very short time (2-3 days). The leachate is then returned to the solid phase for re-

circulation through the solid waste bed to replenish the VFAs concentration. The system

works with a relatively small volume of water (about 25% by volume greater than the

solid waste field capacity) which is constantly re-circulated between solid phase and

methane phase.

The two-phase system has several advantages over the traditional single phase system

(landfills). The total detention time in the two-phase system is considerably shorter than

the detention time in the single phase system. The average duration of two phase system




4/23

is 6-12 months compared to single phase system which could last 30-50 years

(Brummeler et al 1992, Chynoweth et al 1993, Ghosh, 1995, Longworth 1999). The gas

conversion efficiency in two-phase system is also significantly higher than single phase

system. The gas conversion rate for MSW in two-phase system is 0.66-0.85 m3of

methane per kg of volatile solids (VS) consumed. This is compared to 0.22-0.48 m3of

methane/kg of VS consumed for the single phase system (Bae et al 1998, Brummeler et al

1992, Matw-Alvarez et al, 1992, Owens and Chynoweth, 1993,Ghosh, 1995, Beccari et

al, 1998, Pohland, 1975, Strydom et al, 1997). In addition, the methane concentration in

the produced gas is higher in two-phase system than the single phase system. The

methane concentration in two-phase system is 70-85 percent by volume compared to 40-

60 percent for single phase system (Bae et al, 1998, Brummeler et al 1992, Chynoweth et

al 1993, Pohland, 1975, Beccari et al, 1993,Ghosh, 1995, Longworth, 1999, Strydom et

al, 1997).

Phase I Fermentation involves hy drolysis (or liquefaction) of feed solids to monomeric

species and conversion of these to VFAs, hydrogen, C02, and other minor by-products.

Liquefaction-acidification reactions mediated by fermentative acidogens proceed at a fast

rate, and are optimized at an acidic pH (Ghosh, et al., 1987; Speece, 1996). Minor

products of liquefaction include alcohols, ketones, organic and inorganic sulfides,

nitrogen, hydrogen, and other compounds.

Phase 1I Fermentation involves the conversion of the end-products of Phase I

fermentation by acetogenic bacteria to acetate, and hydrogen and C02that are precursors

of the biomethanation process. Acetate is split to methane and C02in equimolar




5/23

quantities by acetoclastic methane bacteria, while hydrogen and C02are converted to

methane by syntrop hic methanogens. The residue is rich in inorganic salts of ammonium

and phosphorus, vitamins, and other nutrients. The acetogenic-methanogenic

fermentation phase proceeds at about one-tenth the rate of acidogenesis, and is optimized

at an alkaline pH and lower redox potential (Ghosh, et al., 1987; Speece 1996). In a

bench scale study, more than 95 vol% of the two-phase system methane was generated by

Phase II or the methane-phase fermenter (Ghosh, 1991).

Research on the development of the two phase fermentation was initiated by Professors

Borchardt (1967) followed by the work of Professors Pohland and Ghosh (1971). The

feasibility of engineering application of phased fermentation by kinetic control involving

adjustment of hydraulic and organic loading rates was demonstrated in the 1970s (Ghosh

and Pohland, 1974; Ghosh, et al., 1975). The two-phase fermentation process has been

applied in commercial-scale for biogasification of municipal biosolids and high strength

industrial effluents in the United States, Germany, Malaysia, India, Egypt, Italy, South

Africa and other countries (Ghosh, et al., 1985; Beccari, 1998; Strydom, 1997). Several

American communities including Louisville, KY, Baltimore, MD, and Blue Plains,

Washington, D.C., and Seatt le, WA are considering installation of two-phase systems to

replace existing single-stage anaerobic digestion. Demonstrated advantages of phased

fermentation are: doubling or tripling of methane production rate relative to conventional

anaerobic digestion (AD), high pathogen kill rates (disinfection), biodegradation of

hazardous substances, elimination of fermenter foaming, and increased process stability

(Ghosh, 1987; Ghosh et al., 87; Ghosh and Buoy, 1993).




6/23

Solid waste bi-phasic fermentation is an extension of the two-phase fermentation p rocess.

In this bi-phasic process, hydrolysis and acidogenesis of a solid bed are induced and

thereafter accelerated by gradual enrichment and intermittent recirculation of a culture of

fermentative organisms (Ghosh, 1985a, 1985b, 1985c).

The solid-state bi-phasic fermentation process is applicable to any high solids-content,

biodegradable, organic feedstock. However, most of the research has been performed

with real and simulated municipal solid waste (MSW). The feedstock used in this work

was a simulated segregated organic solid waste stream from the City of Albuquerque

NM. This waste st ream is largely from the industrial and commercial sector. The City of

Albuquerque NM is interested in attempting to implement this technology at a large pilot

scale, with expansion to full-scale if the pilot scale is successful. Albuquerque has

identified 83 tons/day of segregated high organic waste in their municipal waste stream.

The waste stream characteristics are shown in Table 1 (Glass, 1999).

Table 1. Organic Fraction Separated from commercial/industrial waste stream;

Albuquerque, NM

=========== Tons/Year ============

Category Total Paper Food etc. Yard Tr.

--------- ------ ------ -------- -------Large Retail 12,787 10,381 2,249 157

Educational 10,276 5,388 3,100 1,788

Govt. Office 2,531 2,282 228 21

--------- ------ ------ -------- -------

Totals 25,594 18,051 5,577 1,966




7/23

Results of current bench-scale research have shown that the end products of Phase I, solid

bed fermentation of M SW include: VFAs up to a concentration of 18 g/l, and a gas

mixture of hy drogen (up to 30 mol%), nitrogen (up to 30 mol%), C02(up to 90 mol%),

and methane (up to about 5 mol %) (Ghosh et al., 1997). The acidic products are

conveyed to a separate upflow, packed-bed methane fermenter where the acids are

converted to methane and carbon dioxide. Methane fermenter effluent is recycled back to

the solid-bed reactor to add alkalinity to the solid bed and to provide moisture for further

leachate production. Since the respiration by-products from the acidifiers do not leave the

first phase reactor, the methane concentration in the methane production reactor is 75-

85% instead of the 50-55 % normally observed in a single phase digester. This

performance is very close to the theoretical maximum efficiency for a microbial system

without gas scrubbing. The fermentation process is completed in months instead of the

years required in a conventional landfill. Bench-scale bi-phasic fermentation of

organic-rich MSW showed that about 60% of the organic solids (VS) were gasified.

Methane gas can be used to generate electrical power or liquid fuel, with off-the-shelf

thermal or thermochemical conversion technologies.

The organic release characteristics for typical waste streams is a p otential major issue.

Understanding of the dy namics associated with conversion of the carbon source to VFAs

impacts the size of the solid phase reactor (Phase I) which has a detention time of months

as opp osed to hours in the Phase II reactor. As shown p reviously, the majority of the

waste stream available in the City of Albuquerque, and probably in most citys, is

cellulose based materials. It appears that there are two choices with these materials.




8/23

Accept the energy lose associated with not capturing the full methane production capacity

of this material, and allow most of the energy potential to go into a post anaerobic

treatment composting process. It is noted that this is acceptable, since the compost ing is

a beneficial use of the carbon

From work by Eleazer et al. (1997), it appears that most none cellulose wastes release the

majority of consumable carbon in 60-90 days. The cellulose waste streams such as

office paper appear to y ield a fairly flat release of carbon over 500+ days(Eleazer, et al.

1997). The segregated waste stream from Albuquerque is 71% cellulose based waste

(office paper). Figure 2shows the COD production pattern for the simulated

Albuquerque waste. Clearly there is a quick release of carbon in a 60-90 day window.

The organics remaining after the 60-90 day period will act as food for the composting

process and the composted material will be sold as a beneficial product.

The digested material, although more biologically stable, still represents a demand for

landfill space. These solids go to beneficial use as compost , instead of taking up landfill

space. The composting will keep the material out of the landfill, prevent the eventual

generation of methane in the landfill, and provide a commercially saleable beneficial

product. It is noted that composting the end product of the anaerobic digestion will

further mitigate production of a green house gas. Combined digestion and composting or

co-composting were reported successfully in the Europe and Canada ( Pera, et. al, 1991;

Edelmann and Egeli 1993; Poggi-Varaldo and Oleszkiewicz 1992).

The nutrient-rich process residue from the solid phase reactor is expected to satisfy 503

regulations of U. S. EPA in terms of pathogen density, heavy metal contents, and




9/23

concentration of hazardous substances. The residue has potential, therefore, to be utilized

by urban communities for horticultural app lications, and by farmers for agricultural use.

Markets for these products are well established in many communities.

Since the paper has high lignin which is hard to decompose by anaerobic process, while

food waste, and grass are easily biodegradable through anaerobic digestion that can

recover biogas, there is a good opportunity to optimize the process: first recovering

biogas and breaking down the structure of the paper, then using compost ing process to

decompose the paper and convert the remaining waste stream to a marketable soil

amendment. Also during the composting process, the moisture adjustment can be

achieved by adding leachate from the anaerobic digestion process. This leachate will be

full of nutrients.

MATERIALS AND M ETHODS

The solid phase reactor consisted of a metal container with capacity of 8 m3. The reactor

was sealed with 40 mil (1mm) polyethylene. The container was fitted with an influent

port, an effluent port, and a sprinkler irrigation system for leachate recirculation. The

ratio of the feed stock was 70:20:10 for the paper, food waste and grass, which was

simulated by Albuquerque segregated waste stream. The load consisting of 193 lbs.(87.6

kg) of paper, 70 lbs.(31.8 kg) of food waste and 45 lbs.(20.4 kg) of grass was p laced in

the container. The paper was shred 0.25 in x 11 in( 0.64 cm x 28 cm) office paper. The

food waste was from the university cafeteria and the grass was from the university lawns.




10/23

The volume of water added to the solid phase container was sufficient to provide a

volume of water to recirculate in the solid phase container. This resulted in a total

volume of 100 gallons(380 liters) of water. Water consumption during re-circulation due

to absorption and evaporation, required the periodic addition of water to maintain the re-

circulation volume.

The methane phase reactors consisted of two 12 feet tall (3.66 m), 12 inch (30.5 cm) ID

PVC pipes which were fitted with influent and effluent ports. The columns were filled

with inert commercial packing media to facilitate the bacteria attachment and growth.

The packing had a total porosity of 90 percent resulting in net liquid volume of 50

gallons(190 liters) per column. The columns were designed to operate as upflow

anaerobic filters (UAF).

To start the experiment, water was re-circulated through the solid phase until the pH of

the solid phase leachate was reduced to a value of 5.4, which was within the range of the

optimum environment (pH of 4.0-6.5, (Speece, 1996)) for the acidogenic bacteria.

Leachate was transferred to the UAF once per day. The leachate transfer was increased

incrementally to determine the maximum organic loading rate for each UAF. The

maximum loading rate was determined to be 2.7 kg of Chemical Oxygen Demand (COD)

per cubic meter of UAF per day.

In order to evaluate the effect of temperature on the gasification efficiency, one of UAF

was heated using heat tape. This resulted in a column average temperature of

approximately 150F higher than the ambient average temperature. The second UAF was


Copyright 2001 Water Environment Federation. All Rights Reserved. page 1


11/23

operated at ambient temperature. Liquid samples were collected from the influent and

effluent of the solid phase and UAF and were analyzed for COD, pH.

The composting process was carried out in two 32 gallons(121-liters) reactors. The

compost ing was forced air with the air introduced at the bottom of the reactor and

diffused through a perforated Plexiglas plate. The Average air rate controlled by an in-

line flow meter was 2 liter/min. The feed stock of the compost ing process filled 80 % of

the reactor volume. The composting process lasted 90 days. In addition, gas samples were

collected from both phases and were analyzed for CH4. The starting and ending moisture

and C/N ratio were analyzed. The initial moisture was 62 % by weight and the initial C/N

ratio was 100 : 1.

RESULTS AND ANALYSIS

The experiment was performed from Oct. 7, 1999 to Jan. 28, 2000. The operation stopped

once the COD and VFA production approached low steady values. Figure 2, shows the

influent and effluent COD for both UAFs. The COD reached a peak value of 28,000 mg/l

during the first month of operation, and declined to a value of 5,000 mg/l after 112 days

of operation. The area under the influent COD curve represents 67% of the total volatile

solids originally p resent in the reactor. The remaining 33% of the VS was a pulp and

lignin like residual. The decision to continue the operation until all the VS is converted,

would depend on economic and operational constraints. Figure 2 also shows the effluent

COD from UAFs. The average COD produced by the heated UAF was 13 % lower than

that of ambient UAF.




12/23

Figure 3 shows the cumulative gas production from the UAFs. The comparison shows

that the heated UAF produced 30 percent more gas than the ambient UAF. The higher gas

production in the heated UAF was due to the higher temperature which resulted in higher

COD conversion. As expected, the results show that heating and insulation are major

factors in biogasification of VFAs.

Figure 4shows the gas constituents produced by UAFs. The average methane

concentration for both UAFs was 72 and 76 percent, with a peak value of 79 percent.

There was no significant difference in methane concentration between heated and

ambient UAF. The remaining components were carbon dioxide, oxygen, nitrogen, and

hydrogen sulfide. The methane yields for heated and unheated UAF were 0.33 and 0.3 m3

of methane per kg of COD removed respectively. The COD removal rates for heated and

ambient UAF were 72 and 66 percent respectively.

Table 1. compost characteristics

Before Composting After CompostingVolatile Solids

Reduction

VS Moisture C : N VS Moisture C : N

64 60 66 58 110 90 40 38 51 45 53 50 38 % 37 %

Figure 5shows the temperature profile of the compost. This figure demonstrates a

number of important things. The period of maximum temperature generation lasted for

only 90 days, and generated temperatures between 35 and 40 C. A temperature of 60 C is

required to destroy weed seeds and pathogens. At day 20 nitrogen was added to both




13/23

compost reactors. There was no increase in temperature, which indicates that the low

temperature was not due to a nitrogen limitation. Between days 63 and 78 the cover blew

off from compost reactor #2, which resulted in severe drying of that reactor. This caused

a dramatic temperature drop. When water was added to the reactor, the temperature

returned quickly to 30 C. The fact that compost reactor #1 and #2 were at the same

steady state temperature before and after the drying event, indicated that the system was

not moisture limited. These two factors indicate that the low temperature during the

compost ing was probably due to a lack of available carbon. Improvements in the

compost ing step of this process will probably require the addition of an available carbon

source, such as cow manure.

CONCLUSION

This work shows that paper, food waste and grass can be gasified in a relatively short

time (112 days) in comparison to a normal landfill setting. The results also showed that

the duration of the operation can be further reduced by heating and/or insulating the

system. The effluent gas had an average methane concentration of 74 percent. The

methane gas production rate was approximately (0.03 m3of methane per kg of waste). In

a field scale operation, this p roduction value would be a function of length of time the

feedstock was left in the reactor, which in turn is determined by economic and

operational constraints. After anaerobic digestion, the easily decomposable materials

were converted to biogas, while paper changed to pulp like stuff. The remaining paper

only took 60 days to decompose to a soil like substance during composting.




14/23

Acknowledgements: The authors would like to acknowledge financial assistance from

the Waste Education Research Consortium (WERC)/DOE, and the New Energy

Development Organization (NEDO) of Japan. We would also like to thank the City of

Albuquerque NM for assisting with sample analysis.




15/23

REFERENCE:

Alexiou, I.F., Anderson, G.K. and Ghosh, S., "The use of acidogenic reactors aspretreatment for agro-industrial wastewaters and sludges,"Proc.. Anaerobic Processes

for Bioenergy and Environment: The Nordic Energy Programme, Intl. Conf.', Kollekolle,

Denmark, Jan. (1994a).

Alexiou, I.F., Anderson, G. K. and Ghosh, S., "Pre-acidification Used as Pre-treatmentfor Agroindustrial Wastewaters and Sludges, " Proc., Treatment of Organic Wastes and

Sludges, "Aqua-Enviro " European Conf., Wakefield, UK, Ap ril (1994b).

Bae, J. H.; Cho, K. W.; Lee, S. J.; Bum, B. S.; and Yoon, B. H. Effects Of LeachateRecycle And Anaerobic Digestion Sludge Recycle On The Methane Production From

Solid Wastes Wat. Sci. Tech.1998, 38(2), 159-168

Beccari, M.; Mafone, M. and Torrisi, L Two-reactor System With Partial Phase

Separation For Anaerobic Treatment Of Olive Oil Mill Effluents, Wat. Sci. Tech.1998,38 (4-5), 53-60

Borchardt, J.A.,"Anaerobic Phase Separation by Dialysis Technique," Proc.. Third Intl.

Conf. On Wat. Pollut. Res., 1, 309 (1967).

Brummeler, E. T.; Aarnink, M. M. J.; and Koster, I. W. Dry Anaerobic Digestion Of

Solid Organic Waste In A Biocel Reactor At Pilot-Plant Scale, Wat. Sci. Tech.1992,

25(7), 301-310

Chynoweth, D. P.; Barkdoll, A.W.; Nordstedt, R.A.; Owens, J. M. and Sifontes, J.

Sequential Batch Anaerobic Composting of M unicipal Solid Waste(MSW) And Yard

Waste, Wat. Sci. Tech.1993, 27(2), 77-86

Edelmann, W. and Engeli, G. Combined Digestion And Composting Of Organic

Industrial And Municipal Wastes In Switzerland, Wat. Sci. Tech., 1993, 27 (2), 169-182.

Eleazer, W. E.; Odle, III, W. S.; Wang, Y. and Barlaz, M. A. Biodegradability ofMunicipal Solid Waste Components In Laboratory-Scale Landfills,Environ. Sci.

Technol.1997, 31, 911-917

Ghosh, S. and Pohland, F.G., "Kinetics of Substrate Assimilation and Product Formation

in Anaerobic Digestion,", Jour. Wat. Poll. Control Fed., 46, 4, 748-75 9, April (1974).

Ghosh, S., Conrad, J.R. and Klass, D.L., "Anaerobic Acidogenesis of Sewage Sludge",

Journ. Wat. Pollut. Control Fed., 47, 1, 30-45 (1975).




16/23

Ghosh, S. and Klass, D.L., "Two-Phase Anaerobic Digestion", U.S.Patent 4,022,665,

May 10 (1977).

Ghosh, S., "Two-Phase Anaerobic Digester System," U.S.Patent 4,318,993, March 9

(1982).

Ghosh, S., "Gas Production by Accelerated In-Situ Bioleaching of Landfills, " US.Patent

4,323,367, April 6 (1982a).

Ghosh, S., Henry, M.P. and Sajj ad, A., "Novel Two-Phase Anaerobic Gasification with

Solid-Bed Acid Digestion in Tandem with Fixed-Film Methane Fermentation, " Proc.

International Gas Research Conference, London, England, June 13-16, 1983, Gas

Research Inst., Chicago, IL (1983).

Ghosh, S., "Gas Production by Accelerated Bioleaching of Organic Materials, " U.S.

Patent 4,396,402, Aug. 2 (1983).

Ghosh, S., "Solid-Phase Methane Fermentation of Solid Wastes, " Proc.. Natl. WasteProcessing Conf' Engineering: The Solution, 683-689, ASME, New York (1984).

Ghosh, S., "Leach-Bed Two-Phase Digestion-The Landfill Gas Concept," Symp. Papers,

Energy from Biomass and Wastes IX, D. L. Klass, Ed., Lake Buena Vista, FL., Inst. Gas

Technol, Chicago, IL., 7430762, Jan. 29-Feb. 1 (1985a).

Ghosh, S., "Solid-Phase Digestion of Low-Moisture Feeds," S. Ghosh,In Biotechnol. &

Bioeng. Symp.No 14, 365-382, C. D. Scott , Ed. Johm Wiley & Sons, New York (1985b).

Ghosh, S., "Solid-Phase Methane Fermentation of Solid Wastes, " Jour. EnergyResources Technol., Trans. ASME, 107, 402-405, Sept. (1985c).

Ghosh, S., Ombregt, J. P. and Pypin, P., "Methane Production from Industrial Wastes by

Two-Phase Anaerobic Digestion, Wat. Res., 29, 1083-1088 (1985).

Ghosh, S., "Improved Sludge Gasification by Two-Phase Digestion ",Journal of

Environ. Eng., Amer. Soc. of Civil Engineers, 113, 6, 1265-1284 (1987).

Ghosh, S., Henry, M. P. and Sajj ad, A., Stabilization of Sewage Sludge by Two-Phase

Anaerobic Digestion", EPA 60012-871040, June '87, No. PB 87-1973981AS, Natl. Tech.Info. Service, Springfield, VA (1987).

Ghosh, S., Chynoweth, and D. P., Tarman, P. B., "Two Phase Anerobic Digestion", U.S.

Patent 4,696,746, September 29 (1987).

Ghosh, S. and Lall, U., "Kinetics of Anaerobic Digestion of Solid Substrates", in

Anaerobic Digestion 1988, E. R. Hall and P. N. Hobson, Editors, Advances in Wat. Poll.

Control, Int. Assoc. on Wat. Poll. Res, And Control, 365-376, Pergamon Press (1988).




17/23

Ghosh, S., "Pilot- Scale Demonstration of Two-Phase Anaerobic Fermentation of

Activated Sludge," in Water Science & Technology -Advances in Water PollutionControl, Vol. 23,Part 3, 1179-88, P. Grau and International Association of Water

Pollution Research and Control Program Committee, Editors, Pergamon Press, Oxford,

England (1991).

Ghosh, S. and Buoy, K., "The Acimet Process: An Innovative Approach toBiogasification of Municipal Sludge," Conf Proc.. First Biomass Conference of the

Americas (sponsored by the USDA, USDOE, USEP and Energy, Mines and Resources,

Canada), Burlington, VT, Aug. 30-Sept. 2 (1993).

Ghosh, S., "Commercialization of an Innovative Anaerobic Digestion Process ",Proc..Ann. Symp. International Session Assoc. of Environ. & Sanit. Eng.. Res., Kyoto, Japan, 8,

No. 3, 5-10 (1994).

Ghosh, S., Fukushi, K., Liu, T., Kalra, S., Marigar, C., Hansen, C., DeBirk, L., Bupp, S.,

Sargent, S., Christensen, J., and Millar, J., "Pilot Plant for Biomethanation of DairyIndustry Wastes," proc.. Bioenergy 94: Using Biofuels for a Better Environment, Sixth

National Bioenergy Conference, Reno, NV., Oct. 2-6., The Wester Regional Biomass

Energy Program, C/O WAPA, Golden, CO (1994).

Ghosh, S. Role Of Anaerobic Digestion In Alleviating Environmental Problems In TheUnited States,J. of Hydrau, Coast. And Environ. Eng., 1995,521(8), 239-248

Ghosh, S., Vietez, E. R., Liu, T. and Kato, Y., "Biogasification of Solid Wastes by Two

Phase Fermentation," Proc.., Third Biomass Conf of the Americas, Montreal, Canada,Aug. 23-29 (1997).

Glass, Steve, Personal Communication, November, 1999

Longworth, GMaster Thesis New Mexico State University, 1999

Matw-Alvarez, J.; Liabres, P.; Cecchi, F.; and Pavan, P. Anaerobic Digestion Of The

Barcelona Central Food Market Organic Wastes: Experimental Study,Bioresurce

Technology, 1992, 39, 39-48

Owens, J. M. and Chynoweth, D. P. Biochemical Methane Potential Of Municipal Solid

Waste (MSW) Components, Wat. Sci. Tech., 1993, 27 (2), 1-14

Pera, A.; Vallini, G.; Frassinett i, S. and Cecchi, F. Co-compost ing For ManagingEffluent From Thermophilic Anaerobic Digestion Of Municipal Solid Waste,

Environmental Technology, 1991, 12, 1137-1145




18/23

Poggi-Varaldo, H. and Oleszkiewicz, J. A. Anaerobic Co-composting Of M unicipal

Solid Waste and Waste Sludge At High Total Solids Levels,Environmental Technology,

1991, 13, 409-421

Pohland, F. G. and Ghosh, S. Developments In Anaerobic Treatment Process,

Biotechnol. and Bioeng. Symp.,1971, 2, 85-106

Pohland, F.G. Accelerated solid Waste Stabilization And Leachate Treatment ByLeachate Recycle Through Sanitary Landfills,Progress inWater Technology1975, 7,

753-765

Speece, R. E.Anaerobic Biotechnology for Industrial WastewatersArchae Press1996, p.94

Strydom, J. P.; Britz , T. J. and Mostert, J. F. Two-phase Anaerobic Digestion Of Three

Different Dairy Effluents Using A Hybrid Bioreactor, Water SA 1997, 23 (2), 151-156

Sun, M. L. and Ghosh, S., "Anaerobic Biodegradation of Benzene under Acidogenic

Fermentation Condition," Proc.. Seventh Annual Conf on Hazardous Waste Research, Ed.

L. E. Erickson, Boulder, Co June 1-2, 1992, Kansas State University, Manhattan, Kansas.




19/23

Figure 1. Schematic of two-phase anaerobic digestion system

FeedPump Pump

Solid

Phase

Solid Bed(Acid

Formers)

Anaerobic Filter(Methane

Formers)

Gas

Gas

Feed Return

SolidPhaseRecirculation

Methane

Phase

Gas Phase

Recirculation




20/23

Figure 2. Upflow Anaerobic Filter (UAF) influent and effluent COD in mg/L

0

5000

10000

15000

20000

25000

30000

7-Oct 27-Oct 16-Nov 6-Dec 26-Dec 15-Jan 4-Feb

Date

COD

(mg/L)

Column I Column II Solid phase




21/23

Figure 3. Gas accumulation from the upflow anaerobic filters (UAF)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

27-Oct 6-Nov 16-Nov 26-Nov 6-Dec 16-Dec 26-Dec 5-Jan 15-Jan 25-Jan 4-Feb

Date

Gasproduction(liters)

C I gas accumulation C II gas accumulation




22/23

Figure 4. Upflow anaerobic filters (UAF) gas content.

0

10

20

30

40

50

60

70

80

90

16-Nov 21-Nov 26-Nov 1-Dec 6-Dec 11-Dec 16-Dec

Date

MethaneCo

ntent(%

C I methane Content C II methane content




23/23

Figure 5. Composting Temperatures After Bi-phasic Treatment

0

5

10

15

20

25

30

35

40

45

0 20 40 60 80 100

Days of Composting

Temperature(de

grees

Reator I Reactor II

N added

water added


Documents

Energy Production and Compost Generation From a Segregated Municipal Waste Stream Using Bi-Phasic Anaerobic Digestion_My Paper