Review of literature - INFLIBNETshodhganga.inflibnet.ac.in/bitstream/10603/4093/9/09... · 2015-12-04 · Review of literature In advanced countries, the coagulation–flocculation

Review of literature

The Introduction chapter has been communicated for Invited review as

Saratale R G Saratale G D Parshetti G K Chang J S and Govindwar S P Outlook of bacterial

decolorization and degradation of azo dyes a review International Journal of Environmental

Research and Public Health (2009) (communicated)

11


21 Importance of biological treatment relative to physicochemical methods

Together with industrialization awareness towards the environmental

problems arising due to effluent discharge is of a critical importance A dye

house effluent typically contains 06ndash08 g l-1 dye (Gahr et al 1994) Pollution

caused by dye effluent is mainly due to durability of the dyes in the wastewater

(Jadhav et al 2007) Therefore both color creating and the color using industries

are compelled to search for novel physicochemical treatments and technologies

which are directed particularly towards the decolorization of the dyes from the

effluents There are many reports on the use of physicochemical methods for

color removal from dyes containing effluents (Churchley 1994 Vandevivere et

al 1998 Swaminathan et al 2003 Behnajady et al 2004 Golab et al 2005

Lopez-Grimau and Gutierrez 2005 Santos et al 2007 Wang et al 2007) The

various physicalchemical methods such as adsorption chemical precipitation

photolysis chemical oxidation and reduction electrochemical treatment were

used for the removal of dyes from wastewater effluent (Fig 21)

Fig 21 Treatment methods for the removal of dyes from wastewater effluent

211 Physical and chemical methods

Physical method Chemical method

Adsorption Filtration

Reverse osmosis Electrolysis

Ozonation

Microorganisms

Biological method

Enzymes

Coagulation Floculation

Oxidation

TTrreeaattmmeenntt mmeetthhooddss ffoorr tteexxttiillee eefffflluueennttss

12


In advanced countries the coagulationndashflocculation is most widely used

method in textile wastewater treatment plants It can be used either as a

pre-treatment post-treatment or even as a main treatment system (Gaumlhr et al

1994 Marmagne and Coste 1996) This method can efficiently remove mainly

sulphur and disperse dyes whereas acid direct reactive and vat dyes presented

very low coagulationndashflocculation capacity (Marmagne and Coste 1996

Vandevivere et al 1998) Filtration methods such as ultrafiltration

nanofiltration and reverse osmosis have been used for water reuse and chemical

recovery In the textile industry these filtration methods can be used for both

filtering and recycling It is not only pigment-rich streams but also mercerizing

and bleaching wastewaters The specific temperature and chemical composition

of the wastewater determine the type and porosity of the filter to be applied

(Porter 1997) The main drawbacks of membrane technology are the high

investment costs the potential membrane fouling produces secondary waste

streams which need further treatment (Robinson et al 2001) A very good

option would be to consider an anaerobic pre-treatment followed by aerobic and

membrane post-treatments in order to recycle the water

The adsorption methods for the color removal are based on the high

affinity of many dyes for the adsorbent materials found effective for the removal

of a wide range of dyes The main criteria for the selection of an adsorbent

should be based on the characteristics such as high affinity capacity for target

compounds and the possibility of adsorbent regeneration (Karcher et al 2001)

Activated carbon (AC) is the most common adsorbent and found very effective

to the various types of dyes but due to high cost it is not used conventionally

(Walker and Weatherley 1997 Robinson et al 2001) However its requirement

of various types of adsorbents and also their regeneration or disposal makes the

13


process economically unfeasible (Karcher et al 2001 Anjaneyulu et al 2005)

Some investigators have used alternative materials such as zeolites polymeric

resins ion exchangers and granulated ferric hydroxide In addition to a number

of low-cost adsorbent materials like peat bentonite clay and fly ash have been

investigated for color removal (Ramakrishna and Viraraghavan 1997) Ion

exchange and electro-kinetic coagulation was also found effective but due to

their high sludge producing properties and ineffective to diversity of dyes it

became economically unfeasible hence not accepted widely (Anjaneyulu et al

2005)

Moreover chemical oxidation methods enable destruction or

decomposition of dye molecules In which various types of an oxidizing agent

such as ozone (O3) hydrogen peroxide (H2O2) and permanganate (MnO4) were

used Modification in the chemical composition of a compound or a group of

compounds (for example dyes) takes place in the presence of these oxidizing

agents by which the dye molecule becomes susceptible for the degradation

(Metcalf and Eddy 2003) Ozonation found to be effective due to its high

reactivity with many azo dyes (by breaking azo -N=N- bond) application in

gaseous state no alteration of the reaction volume and providing good color

removal efficiencies (Alaton et al 2002) However it has limitation towards

disperse dyes and those insoluble in water short life time (20 min) low COD

removal as well as the high cost of ozone (Anjaneyulu et al 2005) In advanced

oxidation processes (AOP) (photochemical and photocatalytic) an oxidizing

agents such as O3 and H2O2 or with heterogeneous photocatalysts are used with

catalysts such as TiO2 ZnO2 Mn and Fe in the presence or absence of an

irradiation source are found to be effective by generating (OH-) radical for the

destruction of hazardous dye pollutants (Vandevivere et al 1998 Alaton et al

14


2002 Al-Kdasi et al 2004 Forgacs et al 2004 Anjaneyulu et al 2005) In

Fenton reaction hydrogen peroxide is added in an acid solution (pH 2ndash3)

containing Fe2+ ions for the generation of free hydroxyl radical (OH-) This

method found relatively cheap and also represents high COD removal and

decolorization efficiencies for both soluble as well as insoluble dyes However

high sludge generation due to the flocculation of reagents and dye molecules still

limit this process (Robinson et al 2001 Van der Zee 2002) The H2O2UV

process is the most effective AOP technology mainly because of high color

removal (up to 95 ) no sludge formation and high COD removal in a short

retention time is achieved (Safarzadeh et al 1997) It is found less effective for

disperse vat dyes and highly colored wastewater Formation of byproducts and

inefficient use of UV light increases the cost of the process (Yang et al 1998)

Electrochemical oxidation found to be very effective in which destruction of

organic compounds resulted into non-hazardous products but high cost of the

electricity limits the process (Robinson et al 2001 Morawski 2002) Thus

majority of color removal techniques work either by concentrating the color into

sludge or by the complete destruction of the colored molecule According to

Integrated Pollution Control (IPC) regulations decolorization systems involving

destruction technologies will persist as the transferal of pollution from one part

of the environment to another need to prevent (Pearce et al 2003) Thus

implementation of physicalchemical methods have inherent drawbacks of

being economically unfeasible (more energy and chemicals) unable to complete

removal of the recalcitrant azo dyes andor their organic metabolites because of

the color fastness stability and resistance of azo dyes to degradation

(Anjaneyulu et al 2005 Dhanve et al 2008) generating a significant amount

of sludge that may cause secondary pollution problems substantially increases

15


the cost of these treatment methods and involving complicated procedures

(Zhang et al 2004 Forgacs et al 2004 Eichlerovaacute et al 2005 Kalme et al

2007)

212 Biological methods

Bioremediation is the microbial clean up approach is on the front line and

priority research area in the environmental sciences This field has recent origin

and grown exponentially over the last two decades In this system microbes can

acclimatize themselves to toxic wastes and new resistant strains develop

naturally which can transform various toxic chemicals to less harmful forms

The mechanism behind the biodegradation of recalcitrant compounds in the

microbial system is because of the biotransformation enzymes (Saratale et al

2007a) Several reports suggest the degradation of complex organic substances

which can be brought about by an enzymatic mechanism like laccase (Hatvani

and Mecs 2001) lignin peroxidase (Shanmugam et al 1999) NADH-DCIP

reductase (Bhosale et al 2006) tyrosinase (Zhang and Flurkey 1997) hexane

oxidase (Saratale et al 2007b) and aminopyrine N-demethylase (Salokhe and

Govindwar 2003) etc A number of biotechnological approaches have been

suggested by recent research as of potential interest towards combating this

pollution source in an ecoefficient manner mainly the use of bacteria and often

in combination with physicochemical processes Azo dyes constitute the largest

class of dyes used in industries which are xenobiotic in nature and found to be

recalcitrant to biodegradation The isolation of new strains or the adaptation of

existing ones to the decomposition of dyes will probably increase the efficacy of

bioremediation of dyes in the near future The use of microbial or enzymatic

treatment method for the complete decolorization and degradation of an

industrial dyes from textile effluent possess has considerable advantages 1)

16


eco-friendly nature 2) cost-competitive 3) less sludge producing properties 4)

the end products with complete mineralization or non toxic products and 5)

could help to reduce the enormous water consumption compared to

physicochemical methods (Saratale et al 2009b Rai et al 2005) Moreover the

effectiveness of the microbial decolorization depends upon the adaptability and

the activity of selected microorganisms Large number of species has been tested

for the decolorization and mineralization of various dyes and steadily increasing

in recent years (Pandey et al 2007) The isolation of potent species and there by

degradation is one of the interest in biological aspect of effluents treatment

(Mohan et al 2002) A wide variety of microorganisms are capable of

decolorization of a wide range of dyes using wide range of microorganisms

including bacteria (Parshetti et al 2006 Kalyani et al 2008 Telke et al 2008

Dawkar et al 2008 Saratale et al 2009c Jadhav et al 2009) fungi (Fournier

et al 2004 Saratale et al2006 Machado et al 2006 Humnabadkar et al

2008) yeasts (Lucas et al 2006 Jadhav et al 2007 Saratale et al 2009a)

actinomycetes (Parshetti et al 2007) algae (Acuner and Dilek 2004 Yan and

Pan 2004 Parikh and Madamwar 2005 Gupta et al 2006 Daneshvar et al

2007) and plants (Phytoremediation) (Aubert and Schwitzguebel 2004

Ghodake et al 2009 Kagalkar et al 2009) capable of decolorize and even

completely mineralize many azo dyes under certain environmental conditions

213 Fungal decolorization and degradation of textile dyes

Filamentous fungi are found ubiquitous in the environment inhabiting

ecological niches such as soil living plants and organic waste material The

ability of fungi to rapidly adapt their metabolism to varying carbon and nitrogen

sources is an integrated aspect for their survival This metabolic activity

achieved through the production of a large set of intra and extracellular enzymes

17


able to degrade complex various kinds of organic pollutants (Saratale et al

2007a) In addition to the production and secretion of number of enzymes

filamentous fungi can secrete a great diversity of primary and secondary

metabolites (eg antibiotics) and perform many different complex conversions

such as hydroxylation of complex polyaromatic hydrocarbons organic waste

dye effluents and steroid compounds (McMullan et al 2001 Saratale et al

2007b) Fungal systems appear to be the most appropriate in the treatment of

colored and metallic effluents (Ezeronye and Okerentugba 1999) The ability of

these fungi to degrade such a range of organic compounds results from the

relatively non-specific nature of their ligninolytic enzymes such as lignin

peroxidase (LiP) manganese peroxidase (MnP) and laccase Fungal degradation

of aromatic structures is a secondary metabolic event that starts when nutrients

(C N and S) become limiting (Kirk and Farrell 1987) Therefore while the

enzymes are optimally expressed under starving conditions supplementation of

energy substrates and nutrients are necessary for the propagation of the cultures

(Christian et al 2005)

Most studies on an azo dye biodegradation have focused on the fungal

cultures mainly belonging to white rot fungi and used to develop bioprocesses

for mineralization of azo dyes (Parshetti et al 2007) The Phanerochaete

chrysosporium is the most widely studied of white-rot fungi as well as Trametes

(Coriolus) versicolor Bjerkandera adusta Pleurotus Aspergillus and Phlebia

species and variety of other isolates also studied for the degradation of various

textile dyes (Heinfling et al 1998 Conneely et al 1999 Swamy and Ramsay

1999 Pointing et al 2000 Saratale et al 2006 Humnabadkar et al 2008) A

detailed investigation was also carried out on isolated Geotrichum candidum

Dec1 capable of decolorization a number of anthraquinone dyes (Kim et al

18


1995) The broad substrate specificity exhibited by this isolate is due to

production of extracellular peroxidase-type enzymes and glycosylated

haem-based peroxidase (DyP) (Kim and Shoda 1999a)

However application of white-rot fungi for the removal of dyes from

textile wastewater have inherent drawbacks long growth cycle requiring

nitrogen limiting conditions naturally white rot fungi not found in wastewater

hence the enzyme production may be unreliable (Robinson et al 2001) long

hydraulic retention time for complete decolorization still limit the performance

of the fungal decolorization system (Banat et al 1996 Saratale et al 2009b) as

well as preservation in bioreactors will be a matter of concern (Stolz 2001)

214 Decolorization with yeast

Very little work was devoted to exploring the decolorization ability of

yeast mainly studied for the biosorption It was observed that few ascomycetes

yeast species such as Candida tropicalis Debaryomyces polymorphus (Yang et

al 2003) Candida zeylanoides (Martins et al 1999 Ramalho et al 2002) and

Issatchenkia occidentalis (Ramalho et al 2004) perform a putative enzymatic

biodegradation and consequent decolorization of different azo dyes Earlier

Saccharomyces cerevisiae MTCC-463 was reported to involve in the

decolorization of Malachite Green and Methyl Red (Jadhav et al 2006 Jadhav

et al 2007) S cerevisiae cells also showed bioaccumulation of reactive textile

dye (Remazol Blue Remazol Black B and Remazol Red RB) during growth in

molasses (Aksu 2003) Magnetically modified bakers yeast has been used for

the biosorption of Acridine Orange Aniline Blue Crystal Violet Malachite

Green and Safranine acts as a promising dye adsorbent (ˇSafaˇrikova et al

2005) Biological decolorization of triphenylmethane dyes are widely reported

using red yeasts Rhodotorulae sp and Rhodotorulae rubra (Kwasniewska 1995)

19


Galactomyces geotrichum MTCC 1360 can decolorize triphenylmethane azo

and reactive high exhaust textile dyes as reported earlier (Jadhav et al 2008)

Recently detailed study on the decolorization of Navy Blue HER by using

Trichosporon beigelii NCIM-3326 along with the enzymatic mechanism and

toxicity of degradation products has been reported (Saratale et al 2009a) In a

comparative study on biosorption capacities of different kinds of dried yeasts for

Remazol Blue Candida lipolytica showed the highest dye uptake capacity up to

250 mg g-1 cells (Donmez 2002 Aksu and Donmez 2003)

215 Decolorization with algae

The photosynthetic organisms such as cyanobacteria or algae have a

ubiquitous distribution and observed in all kind of habitats of the world The

literature survey suggests that algae are capable of degrading azo dyes through

an induced form of an azoreductase (Jinqi and Houtian 1992) Color removal by

algae was due to three intrinsically different mechanisms of assimilative

utilization of chromophores for production of algal biomass CO2 and H2O

transformation of colored molecules to non-colored molecules and adsorption of

chromophores on algal biomass Several species of Chlorella (Acuner and Dilek

2004) and Oscillatoria (Jinqi and Houtian 1992) were capable of degrading azo

dyes to their aromatic amines and to further metabolize the aromatic amines to

simpler organic compounds or CO2 Mohan et al (2002) attributes the

decolorization to biosorption followed by bioconversion and biocoagulation It

was reported that more than 30 azo compounds were biodegraded and

decolorized by Chlorella pyrenoidosa Chlorella vulgaris and Oscillateria

tenuis in which azo dyes were decomposed into simpler aromatic amines (Yan

and Pan 2004) Thus the foregoing results could mean that algae can play an

20


important role in the removal of azo dyes and aromatic amines in stabilization

ponds (Banat et al 1996)

216 Decolorization with plant (phytoremediation)

Phytoremediation is considered as a plausible approach for the

remediation of soils and groundwater contaminated with heavy metals and

organic pollutants Recently some studies describe the use of plants for the dye

removal from wastewaters The Rheum rabarbarum mentions a good removal

capacity of sulfonated anthraquinones (Aubert and Schwitzgueacutebel 2004)

Recently narrow-leaved cattails were studied in synthetic reactive dye

wastewater treatment under caustic conditions (Nilratnisakorn et al 2007) Also

Mbuligwe describes a reduction in color of 72-77 in wetlands vegetated with

coco yam plants (Mbuligwe 2005) It was reported that the plant possesses

enzymes that accept anthraquinones as substrates and in cell culture were able to

remove up to 700-800 mg l-1 of anthraquinones with sulphonate groups in

different positions The three plant species (Brassica juncea Sorghum vulgare

and Phaseolus mungo) of different agronomic consequence were evaluated for

the decolorization of the dyes from textile effluent These plants B juncea S

vulgare and P mungo showed textile effluent decolorization up to 79 57 and

53 respectively (Ghodake et al 2008) Similarly an herb Blumea malcommi

was found to degrade textile dye Reactive Red 5B (Kagalkar et al 2009)

However in large scale application of phytoremediation presently faces a

number of obstacles including the level of pollutants tolerated by the plant the

bioavailable fraction of the contaminants and evapotranspiration of volatile

organic pollutants as well as requiring big areas to implant the treatment

(Williams 2002)

217 Bacterial decolorization and degradation of azo dyes

21


Generally the decolorization of azo dyes occurs under conventional

anaerobic anoxic and aerobic conditions by different groups of the bacteria The

mechanism of microbial degradation of azo dyes involves the reductive cleavage

of azo bonds (-N=N-) with the help of azoreductase under anaerobic conditions

resulted into the formation of colorless solutions containing potentially

hazardous-aromatic amines (Chang et al 2000 van der Zee and Villaverde

2005) The resulting intermediate metabolites (eg aromatic amines) are further

degraded aerobically or anaerobically (Seshadri et al 1994) Many recent

researches focus on utilization of microbial biocatalyst to reduce the dye from

the effluent (Hu 1998 Chang et al 2000 Martina Mohorčič 2004) Moreover

the effectiveness of microbial decolorization depends on the adaptability and the

activity of selected microorganisms It has been reported that a wide range of

microorganisms including bacteria fungi yeasts actinomycetes and algae are

capable of degrading azo dyes Moreover most studies on azo dye

biodegradation have focused on the bacteria and fungi The fungal cultures

mainly belonging to white rot fungi have been used to develop bioprocesses for

the mineralization of azo dyes (Parshetti et al 2007) However a long growth

cycle requiring nitrogen limiting conditions and long hydraulic retention time

for complete decolorization still limit the performance of the fungal

decolorization system (Banat et al 1996 Chang et al 2004 Jadhav et al

2008) In contrast bacterial decolorization and degradation of azo dyes has been

of considerable interest since it possesses higher degree of biodegradation and

mineralization diversity towards variety of azo dyes inexpensive and

eco-friendly nature and less sludge producing properties (Verma and Madmawar

2003 Rai et al 2005 Saratale et al 2009c Kalyani et al 2008 Dhanve et al

2008 Saratale et al 2006) Extensive studies have been carried out to determine

22


the role of the diverse groups of bacteria in the decolorization of azo dyes

(Pandey et al 2007)

i) Using pure bacterial culture

The effluents from textile industries are complex containing a wide

variety of dyes and other products such as dispersants acids bases salts

detergents humectants oxidants etc Discharge of these colored effluents into

rivers and lakes results into reduced dissolved oxygen concentration thus

creating anoxic conditions that are lethal to resident organisms Biological

processes provide an alternative to existing technologies because they are more

cost-effective environmentally friendly and do not produce large quantities of

sludge Bacterial decolorization is normally faster compared to fungal system for

the decolorization and mineralization of azo dyes It was observed that the mixed

cultures are apparent as some microbial consortia can collectively carry out

biodegradation tasks that no individual pure strain can undertake successfully

(Nigam et al 1996) However mixed cultures only provide an average

macroscopic view of what is happening in the system and results are not easily

reproduced making thorough effective interpretation difficult For these

reasons a substantial amount of research on the subject of color removal has been

carried out using single bacterial cultures like P mirabilis P luteola

Pseudomonas sp Pseudomonas sp SUK1 and K rosea has shown very

promising results for the dye degradation under anoxic conditions (Chen et al

1999 Chang et al 2001 Yu et al 2001 Kalyani et al 2008 Parshetti et al

2006) In addition there are also several studies describing the decolorization of

reactive dyes mediated by pure bacterial culture such as Exiguobacterium sp

RD3 for Navy Blue HE2R (Reactive Blue 172) (Dhanve et al 2008) Rhizobium

radiobacter MTCC 8161 for Reactive Red 141 (Telke et al 2008) P vulgaris

23


for Scarlet RR Navy Blue HE2R M glutamicus for Scarlet RR Reactive Green

19A (Saratale et al 2009b and c) and isolated bacterium KMK48 for the

degradation of various sulfonated reactive azo dyes (Kodam et al 2005) The

use of a pure culture system ensures the reproducible data and that the

interpretation of experimental observations is easier The detailed mechanisms of

biodegradation can be determined using the tools of biochemistry and molecular

biology These tools may also be used to up regulate the enzyme system to give

modified strains with enhanced activities In our laboratory the metabolic

pathway of particular dyes using pure culture was determined using various

analytical techniques such as Uv-Visible spectroscopy FTIR GCMS AAS

NMR etc The quantitative analysis of the kinetics of azo-dye decolorization by a

particular bacterial culture can be undertaken meaningfully Also the effects of

various physicochemical parameters on the pure bacterial culture were studied in

detail and some of the studies summaries in Table 21

ii) Using co-culture and mixed bacterial cultures

Bacterial decolorization was found more efficient and faster but

individual bacterial strain usually cannot degrade azo dyes completely The

intermediate products are often carcinogenic aromatic amines which need to be

further decomposed (Joshi et al 2008) Thus the treatment systems composed

of mixed microbial populations possess higher degree of biodegradation and

mineralization due to synergistic metabolic activities of microbial community

and offers considerable advantages over the use of pure cultures in the

degradation of synthetic dyes (Khehra et al 2005a) In the microbial consortium

the individual strains may attack the dye molecule at different positions or may

utilize metabolites produced by the co-existing strains for further decomposition

(Chang et al 2004 Forgacs et al 2004 Saratale et al 2009b Patil et al 2008)

24


25

Sphingomonas strain BN6 is able to degrade naphthalene-2-sulphonate a

building block of azo dyes into salicylate ion equivalents The salicylate ion

cannot be further degraded and it is toxic to strain BN6 Therefore

naphthalene-2-sulphonate can only be degraded completely in the presence of a

complementary organism that is capable of degrading the salicylate ion (Moosvi

et al 2005) In addition it can be difficult to isolate a single bacterial strain from

dye-containing wastewater samples and in some instances long term adaptation

procedures are necessary before the isolate is capable of using the azo dye as a

respiratory substrate Several studies reported in the literature concerning the

biodegradation of colored wastewater using mixed bacterial cultures are given in

Table 21

22 Mechanism of color removal

Azo compounds are susceptible to biological degradation under both

aerobic and anaerobic conditions (Field et al 1995) Decolorization of azo dyes

under anaerobic conditions is thought to be a relatively simple and non-specific

process involving fission of the azo bond to yield degradation products such as

aromatic amines The efficacy of various anaerobic treatment applications for the

degradation of a wide variety of synthetic dyes has been many times

demonstrated (Delee et al 1998) Under anaerobic conditions a low redox

potential (lt50 mV) can be achieved which is necessary for the effective

decolorization of the dyes (Beydilli et al 1998 Bromley-Challenor et al 2000)

Color removal under anaerobic conditions is also referred as dye reduction in

which literature mostly covers the biochemistry of azo dye reduction


Table 21 Decolorization of various azo dyes by pure coculture consisting of pure bacterial culture and mixed bacterial culture

Name of strain Name of Dye and Concentration

Condition (pH temp (oC) agitation)

Time (h) Decolorization ()

Reaction Mechanism References

Pure bacterial culture Micrococcus glutamicus NCIM 2168

Reactive Green 19 A (50 mg1-1)

68 37 static

42 100 Oxidative and reductive Saratale et al 2009c

Rhizobium radiobacter MTCC 8161

Reactive red 141 (50 mg1-1)

70 30 static 48 90 Oxidative and reductive Telke et al 2008

Pseudomonas sp SUK1

Red BLI (50 mg1-1) 65 -70 30 static 1 99 AND and NADH-DCIP reduction

Kalyani et al 2007

Pseudomonas sp SUK1

Reactive Red2 (5 g1-1) 62-75 30 static 6 96 LiP and azoreductase Kalyani et al 2008

Pseudomonas desmolyticum NCIM 2112

Red HE7B (100 mg1-1) 68-80 30 static 72 95 LiP and azoreductase Kalme et al 2007

Comamonas sp UVS Direct red 5B (1100 mg1-1)

65 40 static 13 100 LiP and Laccase Jadhav et al 2008

Unidentified bacterium KMK 48

Reactive Red 2 Reactive Red 141 Reactive Orange 4

Neutral pH room temp aerobic

30 100 Reduction Kodam et al 2005

26


Reactive Orange 7 Reactive Violet 5 (200-1000 mg1-1 each)

Proteus mirabilis RED RBN (1g1-1)

65ndash75 30ndash35 static 20 95 Reductive followed by biosorption

Chen et al 1999

Exiguobacterium spRD3

Navy Blue HE2R (50 mg1-1)

70 30 static 48 91 LiP Laccase and azoreductase

Dhanve et al 2008

Aeromonas hydrophila

Red RBN (3000 mg1-1)

55-100 20-35 NA 8 90 NA Chen et al 2003

Pseudomonas aeruginosa NBAR12

Reactive Blue 172 (500 mg1-1)

70-80 40 static 42 83 Azoreductases flavin reductases or peroxidases

Bhatt et al 2005

Bacillus sp Congo Red (100ndash300 mg1-1)

70 37 NA 24ndash27a 12b

100a

100b

Effect of sonication Kannappan et al 2009

K1ebsi1e11a pneumoniae R5-13

Methy1 Red (100 mg1-1)

60-80 30 200 rpm 168 100 Reduction Wong and Yuen 1996

Rhodopseudomonas palustris AS12352

Reactive Brilliant Red X-3B (50 mg1-1)

8 30ndash35 anaerobic 24 90 Azoreduction Liu et al 2006

Citrobacter sp Azo and Triphenylmethane dyes (5 microM)

7ndash9 35ndash40 static 1 100 Adsorption An et al 2002

S chromofuscus A11 Various azo dyes (50 mg1-1 each)

NA 37 200 rpm 168 70-98 NA Pasti-Grisby et al 1996

27


Pseudomonas luteola RP2B (Reactive Red 22) (100 ppm)

NA 28 Shaking-static incubation (100 rpm for 48 h then at static for 4 days)

120 95 Azoreduction Hu 1998

Shewanella putrefaciens AS96

Acid Red 88 Direct Red81 Reactive Black 5 Dieperse Orange 3 (mixture of these 4 dyes) (100 mg1-1)

NA NA Static

4 6 8

100 100 100

NA Khalid et al 2008

Shewanella decolorationis S12

Acid Red GR NA 30 c and d 68c

10d

100c

100d

Azoreduction Xu et al 2007

Paenibacillus azoreducens sp nov

Remazol Black B NA 37 100 mg dm3

24 98 NA Meehan et al2001

Shewanella putrefaciens

Remazol Black B 8 reactive and anthraquinone dye

8 35 static NA 95 NA Bragger et al1997

Desulfovibrio desulfuricans

CI Reactive Orange 96 NA 28 Anaerobic 2 95 Reduction Yoo et al 2000

Pseudomonas luteola

Reactive azo dyes Direct azo dyes and leather

NA Static NA 24-144 59ndash99 NA Hu 2001

28


dyes (100 mg1-1)

Bacillus fusiformis KMK5

Disperse Blue 79 (DB79) and Acid Orange 10 (AO10) (15 g1-1)

NA anoxic NA 48 100 Azoreductase Kolekar et al 2008

Aeromonas hydrophila var 24 B

Various azo dyes (10-100 mg1-1)

NA 24 50-90

Azoreductase (cell free extract)

Idaka and Ogawa 1978

Bacillus subtilis IFO 13719

2-carboxy 4- dimethyleamino benzene (0045 mmol)

NA 20 min

100 Azoreductase (in growing cells)

Yatome et al 1991

Klebsiella pneumoniae RS-13

Methyl Red (100 mg1-1)

NA 24 100

Azoreduction Wong and Yuen 1996

Sphingomonas sp BN6

Acid azo dyes Direct azo dyes and Amaranth

NA NA Reduction Russ et al 2000

Pseudomonas luteola

CI Reactive Red 22 Agitation without aeration and with a constant dye loading rate of 200 mg h-1

NA 1137 mg dye g cell-1 h-1

NA Chang and Lin 2000

Sphingomonas sp BN6

Amaranth (sulfonated azo dye)

NA NA Azoreduction Keck and Kudlich et al 1997

Bacillus subtilis p-Aminoazobenzene (PAAB)

NA anoxic NA 25 100 NA Zissi and Lyberatos 1996

29


(102 to 75 mg1-1)

Pseudomonas luteola

4 reactive azo dyes NA static NA 42 37ndash93 NA Hu 1990

Pseudomonas cepacia 13NA

CI Acid Orange 12 CI Acid Orange 20 CI Acid Red 88

NA 68 90 NA Ogawa et al 1986

Pseudomonas sp Orange I Orange II

NA 35 90 Azoreduction Kulla et al 1983

Trichosporon beigelii NCIM-3326

Navy Blue HER (50 mg1-1)

70 37 static

24

100

Oxidative and reductive Saratale et al 2009b


Reactive Orange 96 Reactive Red 120 (03 mmol L-1)

113 37 NA Within 2 h from 360 to 362 h

95 Reduction Yoo et al 2000

Micrococcus glutamicus NCIM 2168

Scarlet RR and mixture of 12 dyes (50 mg1-1 each)

69 37 static 20 100 Oxidative and reductive This study

Proteus vulgaris NCIM 2027

Green HE4BD (50 mg1-1)

70 37 static

72

100

Reduction This study


Scarlet RR Navy Blue HE2R (50 mg1-1each)

70 37 static 70 37 static

14 9

100 100


Co culture consisting of pure bacterial culture

30


Consortium-GR (P vulgaris and M glutamicus)


70 37 static

3 100 Reduction

Saratale et al 2009a


Green HE4BD and mixture of 10 dyes (50 mg1-1)

68 37 static

24 100 Oxidative and reductive This study

Enterobacter sp Serratia sp Yersinia sp Erwinia sp

Reactive Red 195 (30 mg1-1)

70 37 150 rpm 48 90 NA Jirasripongpun et al 2007

Consortium two isolated strains (BF1 BF2) and a strain of Pseudomonas putida (MTCC-1194)

Direct Yellow 86 Basic Orange 2 Reactive Green 19 Direct Blue 54 Reactive Blue 171 Reactive Red 141 Acid Red 260

(50 mg1-1 each)

9ndash105 28 120 rpm 168 80 NA Resmi et al 2004

Microbial consortium(white-rot fungus 8-4 amp Pseudomonas 1-10)

Direct Fast Scarlet 4BS (50 mg1-1)

4-9 20-40 NA 24 991 NA Fang et al 2004

Four bacterial isolates consortium Bacillus cereus (BN-7)

Acid Red 88 Acid Red 119 Acid Red 97

70 35 100 rpm 24 24 24

78 99 94

Azoreduction Khehra et al 2005

31


Pseudomonas putida (BN-4) Pseudomonas fluorescence (BN-5) and Stenotrophomonas acidaminiphila (BN-3)

Acid Blue 113 Reactive Red 120 (60 mg1-1 each)

24 24

99 82

Mixed bacterial consortium JW-2

Reactive Violet 5R (100 ppm)

65 to 85 25 to 37 static 36 100 NA Moosvi et al 2007

Bacterial consortium (TJ-1) Aeromonas

caviae Proteus mirabilis and

Rhodococcus globerulus

Acid Orange 7 (AO7) (200 mg1-1)

NA 30 microaerophilic condition

16 90 NA Joshi et al 2008

Bacterial consortium SV5

Ranocid Fast Blue (100 ppm)

70 37 static 24 100 NA Mathew and Madamwar 2004

Bacterial consortium Direct Red 81 (DR 81) (200 mg1-1)

70 37 NA 35 90 NA Junnarkar et al 2006

Cyanobacterial cultures isolated (Gloeocapsa pleurocapsoides and Chroococcus minutus)

Acid Red 97 and FF Sky Blue Amido Black 10B (100 mg1-1)

NA 27 static 26 days 78-90 Oxidative enzymes Parikh and Madamwar 2005

Acclimatized Reactive Black 5 NA 37 static anaerobic 48 70ndash90 Enzyme secretion Dafale et al 2007

32


Microbial consortium

Pseudomonas aeruginosa and Bacillus circulans and (NAD1 amp NAD6) isolates

(100 mg1-1) batch

Five-member bacterial consortium

Alcaligenes faecalis Sphingomonas sp EBD Bacillus subtilis Bacillus thuringiensis and Enterobacter

cancerogenus

Direct Blue-15 (50 mg1-1)

NA 37 static 24 9214 NA Kumar et al 2007

Bacterial consortium RVM111

Reactive Violet 5 (200 mg1-1)

65 to 85 25 to 40 NA 37 94 NA Moosvi et al 2005

Consortium of

Alcaligenes faecalis Commomonas acidovorans

Remazol Black B NA 48 95 NA Oxspring et al 1996

Mixed bacterial cultureMixed culture Reactive Black 5 60-70 RT NA 48 90 Two stage anaerobic- Mohanty et al

33


(100-3000 mg1-1) aerobic treatment 2006 Dried activated sludge Reactive Black 5

(116 mg1-1) 20 20 NA 30 min 50 Adsorption Gulnaz 2005

Mixed bacterial cultures

Mixture of azo- and diazo-reactive dyes

NA 96 80 NA Nigam et al 1996


Diazo-linked chromophore

Use of triple mix gas H2-10 CO2-10 N2-80 at 30degC strictly anaerobic conditions

48 85 Flavin coenzymes

Knapp et al (1995)

Mixed cultures Reactive and disperse textile dyes (05 g1-1)

6 37 120 rpm 120-240 100 NA Asgher et al 2007

Methanogenic and Mixed bacteria cultures

CI Acid Orange 7 (60-300 mg1-1)

NA 37 NA 140 96 The anaerobic batch reactors

Braacutes et al 2001

Isolated halophilic and halotolerant bacteria

Textile azo dyes including Remazol Black B Maxilon Blue Sulphonyl Scarlet BNLE Sulphonyl Blue TLE Sulphonyl Green BLE Remazol Black N and Entrazol Blue IBC (5000 ppm)

5ndash11 25ndash40 static 96 100 Azoreductase Asad et al 2007

34


Mixed culture of bacteria

Remazol Brilliant Orange 3R Remazol Black B and Remazol Brilliant Violet 5R (05-10 g1-1)

NA 30 200 rpm sequential anaerobic-aerobic treatment process

24 24

789 90

NA

Supaka 2004

Mixed-culture Methyl Red 6 30 NA 16 82 Azoreduction Adedayo et al 2004

Mixed microbial culture

Direct Black-38 (100 mg1-1)


Activated sludge obtained from domestic and industrial

effluent treatment plants

Reactive Red 31 (20-30 mg 1-1)

Anaerobic packed bed reactor followed by an aerobic stirred tank reactor

51 90ndash93 NA Bromley-Challenor et al 2004

Original seed sludge collected from a municipal wastewater treatment plant

CI Acid Red 42 CI Acid Red 73 CI Direct Red 80 CI Disperse Blue 56

NA 80 90 NA Goncalves et al 2000

Mixed bacterial population with sulphate-reducing bacteria and a methanogenic

Wastewater containing

up to 15 different sulfonated azo dyes

An anaerobic baffled reactor

NA NA NA Plumb et al 2001

35


population Mixed and methanogenic cultures

CI Acid Orange 7 NA NA 94 Azoreduction Bras et al 2001

Sulphate-reducing bacteria methane producing bacteria and fermentative bacteria in an anaerobic mixed culture

Hydrolysed CI Reactive Orange 96

NA 40 30

95 90

NA Yoo et al 2001

An uncharacterized aerobic biofilm Strain 1CX (Sphinogomonas sp) and Strain SAD4I (Gram-negative bacterium)

Acid Orange 7 A rotating drum bioreactor containing the biofilm

1 90 NA Coughlin et al 2002

Bacillus cereus Sphaerotilus natans Arthrobacter sp activated sludge

Azo dyes NA NA Anoxic conditions NA NA Reduction Wuhrmann et al 1980

36


Field-collected and laboratory cultures

CI Acid Orange 6 CI Basic Violet 1 CI Basic Violet 3

NA NA Aerobic condition NA NA NA Michaels and Lewis 1986

Anaerobic digester sludge and aeration tank mixed liquor

CI Acid Orange 10 CI Acid Red 14 CI Acid Red 18

2-stage anaerobic-aerobic (fixed film fluidised bedsuspended growth activated sludge) reactor

NA 65ndash90 NA Fitzgerald and Bishop 1995


Reactive dyes diazo dyes azo dyes disperse dyes and phthalocyanine dyes

Anaerobic conditions 48 100 NA Nigam et al 1996

Aerobic mixed bacterial culture

Cationic chromium- containing azomethine dye

NA NA NA Adsorption Matanic et al 1996

Thermophilic anaerobic bacterial culture

Various azo and diazo reactive dyes

NA 48 68ndash84 NA Banat et al 1996

Sludge from textile wastewater treatment plant (Inclined Tubular Digester) granules

Simulated textile wastewater containing Procion Red HE7B

Upflow Anaerobic Sludge Blanket (UASB)

NA 78 NA OrsquoNeil et al 1999

37


38

from paper pulp processing plant (Upflow Anaerobic Sludge Blanket)

Four bacterial strains (Pseudomonas) isolated from dyeing

effluent-contaminated soils

Orange G Amido Black 10B Direct Red 4BS Congo Red

NA 1125 1349 mg l-1 d-1

609

NA Rajaguru et al 2000

Mixed culture from upward-flow anaerobic sludge bed (UASB) reactor

20 selected azo dyes (100-300 mglminus1)

NA 1 to 100 100 NA van der Zee et al 2001

a Without sonication pretreatment b With sonication pretreatment c Anaerobic condition d Microaerophilic DO range 02 to 05 mgl-1 150 rpm NA- Not available


The mechanism of microbial degradation of azo dyes involves the reductive

cleavage of azo bonds (ndashN=Nndash) with the help of azoreductase under anaerobic

conditions involves a transfer of four-electrons (reducing equivalents) which

proceeds through two stages at the azo linkage and in each stage two electrons

are transferred to the azo dye which acts as a final electron acceptor resulted

into dye decolorization and the formation of colorless solutions The resulting

intermediate metabolites (eg aromatic amines) are further degraded aerobically

or anaerobically (Chang et al 2000 2004) Thus in the presence of oxygen

usually inhibits the azo bond reduction activity since aerobic respiration may

dominate utilization of NADH thus impeding the electron transfer from NADH

to azo bonds (Chang et al 2004) The potential toxicity mutagenicity and

carcinogenicity of such compounds are well documented and have been

reviewed elsewhere (Chung et al 1992)

Reaction mechanism

(R1ndashN=NndashR2 ) + 2e_ +2H+ mdashgt R1ndashHNndashNHndashR2

(Hydrazo intermediate)

(R1ndashHNndashNHndashR2)+ 2e_ +2H+ mdashgt R1-NH2+ R2-NH2

(Reductive cleavage of the azo bond)

Much of the experimental work involving the anaerobic decolorization of dyes

(predominantly azo dyes) was conducted using mono cultures Species of

Bacillus Pseudomonas Aeromonas Proteus Micrococcus and purple

non-sulphur photosynthetic bacteria were found to be effective in the anaerobic

degradation of a number of dyes (Horitsu et al 1977 Chang et al 2001

Saratale et al 2009bc Kalme et al 2008) The anaerobic reduction of azo dyes

39


utilized in the textile industry by a strain of Bacillus cereus isolated from soil

(Wuhrmann et al 1980) However the permeation of the dyes through

biological membrane into the microbial cells was cited as the principal

rate-limiting factor for decolorization (Kodam et al 2006)

In contrast under aerobic conditions the enzymes mono- and

di-oxygenase catalyze the incorporation of oxygen from O2 into the aromatic

ring of organic compounds prior to ring fission (Madigan et al 2003) However

in the presence of specific oxygen-catalysed enzymes called azo reductases

some aerobic bacteria are able to reduce azo compounds and produce aromatic

amines (Stolz 2001) Examples of aerobic azo reductases were found in

Pseudomonas species strains K22 and KF46 (Zimmermann et al 1982 1984)

These enzymes after purification characterization and comparison were shown

to be flavin-free The aerobic azo reductases were able to use both NAD(P)H and

NADH as cofactors and reductively cleaved not only the carboxylated growth

substrates of the bacteria but also the sulfonated structural analogues Recently

Blumel and Stolz (2003) cloned and characterized the genetic code of the aerobic

azo reductase from Pagmentiphaga kullae K24 Only few bacteria with

specialized azo dye reducing enzymes were found to degrade azo dyes under

fully aerobic conditions (Zimmerman et al 1882 1984 Nachiyar et al 2003

Nachiyar et al 2005)

23 Factors affecting bacterial decolorization

Optimization of operating system is necessary to obtain maximum rate of

decolorization of azo dyes The efficiency of biological treatment systems is

greatly influenced by the various physicochemical parameters such as level of

aeration temperature pH the dye structure its initial concentration effect of

different media composition and supplementation of different carbon and

40


nitrogen sources to enhance the decolorization performance The concentrations

of the electron donor and the redox mediator must be optimized with the amount

of biomass in the system and the quantity of dye present in the wastewater to

improve the further treatment process The chemical composition of textile

wastewater is usually subject to daily and seasonal variations and includes

organics nutrients sulphur compounds salts and different toxic substances

(Pearce et al 2003) Presence of these compounds may have an inhibitory effect

on the dye decolorization process The ability of the bacterial cells for dye

decolorization must be determined at different conditions since the dyes are

intentionally designed to resist degradation and their concentration may have

low removal efficiency by various treatments systems (Philippe et al 1998)

Therefore the effect of each of the factors on the dye decolorization must be

determined prior to the treatment of the industrial wastewater by biological

means

231 Oxygen

The most important factor to consider is the effect of oxygen on the cell

growth and dye reduction It was observed that during the cell growth stage

oxygen will have a significant effect on the physiological characteristics of the

cells During the azo dye reduction cleavage stage with the help of azoreductase

if the extra cellular environment is aerobic the high-redox-potential electron

acceptor oxygen may inhibit the dye reduction mechanism (Chang et al 2004)

Similar results were observed in the studies on pure bacterial strains such as

Pseudomonas luteola Proteus mirabilis Pseudomonas sp SUK1 Proteus

vulgaris NCIM-2027 Micrococcus glutamicus NCIM-2168 (Chen et al 1999

Chang et al 2001 Kalyani et al 2008 Saratale et al 2009b Saratale et al

2009c) This is because of the electrons liberated from the oxidation of electron

41


donors by the cells are preferentially used to reduce oxygen rather than the azo

dye and the reduction product water is not a reductant (Yoo et al 2001) Also

the postulated intermediates of the dye reduction reaction which include the

hydrazine form of the dye and the azo anion free radical form of the dye tend to

reoxidize by molecular oxygen (Zimmerman et al 1982) From these

observations it was recommended that for efficient color removal aeration and

agitation which increases the concentration of oxygen in solution should be

avoided (Chang and Lin 2000) It was also noteworthy that inhibition of azo dye

reduction under aerobic conditions inclines only to be a temporary effect rather

than an irreversible effect If the air is replaced with oxygen free nitrogen the

reducing activity is restored and occurs at a similar rate to that which was

observed under continuous anaerobic conditions (Bragger et al 1997)

However aerobic conditions are required for the complete mineralization

of the reactive azo dye molecule as the simple aromatic compounds produced by

the initial reduction are degraded via hydroxylation and ring-opening in the

presence of oxygen (Chang et al 2001 Pandey et al 2007) Thus for the most

effective wastewater treatment a two-stage process is necessary in which oxygen

is introduced after the initial anaerobic reduction of the azo bond has taken place

The balance between the anaerobic and aerobic stages in this treatment system

must be carefully controlled because it is possible for the re-aeration of a reduced

dye solution to cause the color of the solutions to darken However when the

correct operating conditions have been established many strains of bacteria are

capable of achieving high levels of decolorization when used in a sequential

anaerobicaerobic treatment process (Khehra et al 2006)

42


232 Temperature

The literature survey suggests that the rate of color removal increases

with an increasing temperature up to certain limit afterwards there is marginal

reduction in the decolorization activity It was observed that the temperature

required to produce the maximum rate of color removal tends to correspond with

the optimum cell culture growth temperature of 35ndash45 degC The decline in color

removal activity at higher temperatures can be attributed to the loss of cell

viability or due to the denaturation of an azo reductase enzyme (Chang et al

2001 Telke et al 2008 Saratale et al 2009b) However it has been shown that

with certain whole bacterial cell preparations the azo reductase enzyme is

relatively thermo stable and can remain active up to temperatures of 60 degC over

short periods of time (Pearce et al 2003) Immobilization of the cell culture in a

support medium results in a shift in the optimum color removal temperature

towards high values because the microenvironment inside the support offers

protection for the cells (Chang et al 2001 Pearce et al 2003)

233 pH

The medium pH is also important factor for better decolorization activity

In many studies it was observed that the optimum pH for color removal is often

at a neutral pH or at slightly alkaline pH The rate of color removal was higher at

only optimum pH but tends to decrease rapidly at strongly acid or strongly

alkaline pH In our laboratories similar results were observed with many

microbial strains (Table 21) The interesting results were observed with the

consortium-GB consisting of Galactomyces geotrichum MTCC1360 and

Bacillus sp VUS where the decolorization was not pH dependent Complete

decolorization was observed in the pH range from 5 to 9 (Jadhav et al 2008)

Biological reduction of the azo bond can result in an increase in the pH due to the

43


formation of aromatic amine metabolites which are more basic then the original

azo compound (Willmott 1997) Altering the pH within a range of 70 to 95

has very little effect on the dye reduction process Chang et al (2001) found that

the dye reduction rate increased nearly 25-fold as the pH was raised from 50 to

70 while the rate became insensitive to pH in the range of 70ndash95

234 Dye concentration

The concentration of dye substrate can influence the efficiency of dye

removal through a combination of factors including the toxicity of the dye (and

co-contaminants) at higher concentrations and the ability of the enzyme to

recognize the substrate efficiently at very low concentrations that may be present

in some wastewaters Decrease in the decolorization rates may occur due to the

toxicity of the dye to bacterial cells andor inadequate biomass concentration (or

improper cell to dye ratio) for the uptake of higher concentrations of dye

(Saratale et al 2006 Jadhav et al 2008a) Similar results were observed by

isolated Exiguobacterium sp RD3 Pseudomonas sp SUK1 Proteus vulgaris

NCIM 2027 Micrococcus glutamicus NCIM-2168 for the decolorization of

various reactive group of azo dyes (Dhanve et al 2008 Kalyani et al 2008

Saratale et al 2009b Saratale et al 2009c) It was also observed that reactive

group azo dyes having sulfonic acid (SO3H) groups on aromatic rings greatly

inhibited the growth of microorganisms at higher dye concentration (Chen et al

2003 Kalyani et al 2008) Sani and Banerjee (1999) found that dyes with

concentrations of 1-10 μM were easily decolorized but when the dye

concentration was increased to 30 μM color removal was reduced Surprisingly

Dubin and Wright (1975) reported the absence of any effect of dye concentration

on the reduction rate This observation is compatible with a non-enzymatic

reduction mechanism that is controlled by processes that are independent of the

44


dye concentration Moreover the kinetic constants that govern process efficiency

in common with other enzyme catalysed processes can be described using

MichaelisndashMenten kinetics

where v is the observed velocity of the reaction at a given substrate concentration

[S] Vmax is the maximum velocity at a saturating concentration of substrate and

Km is the Michaelis constant The application of MichaelisndashMenten kinetics can

allow predictions to be made on process efficiency including the degree of

biomass loading or the operational temperature needed to maintain dye removal

at a given efficiency within the constraints set by the reactor volume available

the background solution composition and flow-rates

235 Dye structure

The chemical structure of textile dyes also affects the bacterial

decolorization performance It was reported that dyes with simple structures and

low molecular weights exhibit higher rates of color removal whereas color

removal rate is lower in the case of dye with substitution of electron withdrawing

groups viz (ndashSO3H ndashSO2NH2) in the para position of the phenyl ring relative to

the azo bond and high molecular weight dyes (Sani and Banerjee 1999) Nigam

et al (1996) established that azo compounds with a hydroxyl group or with an

amino group are more likely to be degraded than those with a methyl methoxy

sulpho or nitro groups Moreover color removal rate is also related to the number

of azo bonds in the dye molecule like for monoazo dyes the color removal rate is

faster than the diazo or triazo dyes (Hu 2001) Hitz et al (1978) depicts that

decolorization rate is dependent on dye class like (a) acid dyes exhibit low color

removal due to the number of sulphonate groups in the dye (b) direct dyes exhibit

45


high levels of color removal that is independent of the number of sulphonate

groups in the dye and (c) reactive dyes exhibit low levels of color removal

Sulfonated reactive group of azo dyes are normally considered to be more

recalcitrant than carboxylated azo dyes The rate limiting step during

decolorization of sulfonated azo dyes is the permeation through the bacterial cell

membrane required for reduction of azo dyes (Lourenco et al 2000 Kodam et

al 2006) It was also observed that the enzyme (azoreductase) production was

related with particular dye structures (Kulla 1981) Some azo dyes are more

resistant to removal by bacterial cells (Bras et al 2001) In the case of the

terminal non-enzymatic reduction mechanism reduction rates are influenced by

changes in an electron density in the region of the azo group causes an increase in

the reduction rate (Walker and Ryan 1971) Hydrogen bonding in addition to the

electron density in the region of the azo bond has a significant effect on the rate of

reduction (Beydilli et al 2000)

236 Electron donor

Literature survey suggests that the oxidation of organic electron donors

andor hydrogen is coupled to the color removal process Recently it was

observed that the addition of electron donors such as glucose or acetate ions

apparently induces the reductive cleavage of azo bonds (Bras et al 2001) The

thermodynamics study shows that the different electron-donating half-reactions

are different due to which the reaction rate is likely to be influenced by the type of

electron donor It was also important to determine the physiological electron

donor for each biological color removal process because it not only induces the

reduction mechanism but also stimulates the enzymatic system responsible for

the reduction process (Van der Zee et al 2001 Pearce et al 2003) It was

observed that the formate acts as a most effective electron donor for the

46


anaerobically induced electron transfer pathway to the dye molecule it may be

due to the pathway which shows involvement of formate dehydrogenase enzyme

(Lloyd et al 1997) Yoo et al (2001) found that the products of cell lysate

residue can function as electron donors for an anaerobic azo dye reduction with

the active cells metabolizing the lysis products Certain chemicals such as

thiomersal and p-chloromercuibenzoate inhibit the alcohol dehydrogenase of

NADH-generating systems required to generate reducing equivalents for dye

reduction Therefore the rate of formation of NADH would be rate-limiting

causing inhibition of azo dye reduction (Gingell and Walker 1971)

Coenzyme-reducing equivalents that are involved in normal electron transport by

the oxidation of organic substances may act as the electron donors for azo dye

reduction (Plumb et al 2001)

237 Redox mediator

Rate determining factors for the dye reduction reaction involving the

redox mediator include the redox potential of the mediator in relation to the azo

dye and the specificity of the reducing enzymes Sulfonated group of azo dyes

will pass through the cell membrane where the dye reduction reaction takes

place by using extracellular reducing activity (Keck et al 1997) It was found

that the reducing activity get induced in the presence of redox mediator

compounds such as flavins to shuttle reduction equivalents from the cells to

facilitate the non-enzymatic reduction of the extracellular azo dye (Plumb et al

2001) A very small concentration of the redox mediator is sufficient for this type

of electron transfer Redox mediators are characterized by a redox potential

ranging from minus200 to minus350 mV (Semde et al 1998) The addition of synthetic

electron carriers enhances the rate of reduction of azo dyes by bacterial cells

Quinonendashhydroquinone most widely used as redox mediators (Keck et al 1997)

47


The application of natural biodegradable quinones such as lawsone has

technical potential for color removal treatment systems because the reduction rate

is increased without adding any environmentally problematic substances (Rau et

al 2002) Lourenco et al (2001) observed some color removal in the presence

of autoclaved cells suggesting the existence of an active reducing factor that is

capable of dye reduction in the absence of microbial activity

238 Redox potential

It was observed that color removal depends on the redox potential of the

electron donors and acceptors because the rate-controlling step involves redox

equilibrium between the dye and the extracellular reducing agent The redox

potential can be measured with an ease with which a molecule will accept

electrons and can be reduced Therefore the more positive the redox potential

the more readily the molecule get reduced (Bragger et al 1997) The results

suggest that the rate of color removal will increase with increasing (more

positive) half-wave potential of the azo substrate It was reported that there is a

linear relationship between the logarithm of color removal rate and the half-wave

potential of the substrate (Bragger et al 1997) Thus under anaerobic conditions

establishment of low oxidationndashreduction potentials (ltminus400 mV) enhances the

high color removal rates and has an effect on the profile of metabolites that are

generated during the reduction process (Lourenco et al 2001) It was reported

that color removal rate is highest when the redox potential of the system is at its

most negative and the rate falls as the redox potential of the system rises

(Bromley-Challenor et al 2000)

24 Enzymes involved in the decolorization and degradation of dyes

The possible enzymes involved in the diverse biochemical reactions are

present in microorganisms those can efficiently used for the bioremediation to

48


treat environmental problems due to their catalytic properties Recently the

enzymatic approach has attracted much interest in the decolorizationdegradation

of the textile and other industrially important dyes from wastewater as an

alternative strategy to conventional physicochemical treatments having inherent

drawbacks The oxidoreductive enzymes are responsible for generating highly

reactive free radicals that undergo a complex series of spontaneous cleavage

reactions It was observed that due to the susceptibility of enzymes to

inactivation by the presence of the other chemicals it is likely that enzymatic

treatment will be the most effective in those streams that have the highest

concentrations of target contaminants and the lowest concentration of other

contaminants that may tend to interfere with the enzymatic treatment Mainly the

oxidoreductive enzymes such as lignin peroxidases manganese peroxidases

laccases azoreductases riboflavin reductase and NADH DCIP reductases has

been exploited in the decolorization and degradation of dyes and described in

this section (Das and Reddy 1990 Heinfling et al 1998 Campos et al 2001

Suzuki et al 2001 Nyanhongo et al 2002 Ryan et al 2003 Maier et al

2004)

241 Oxidative enzymes

i) Lignin peroxidase (EC 111114)

Lignin peroxidase (LiP) was first discovered based on the

H2O2-dependent Cα-Cβ cleavage of lignin model compounds and subsequently

shown to catalyze depolymerization of methylated lignin in vitro (Glenn et al

1983 Tien and Kirk 1983 Gold et al 1984) Mainly lignin peroxidases (LiP)

catalyze the oxidation of nonphenolic aromatic lignin moieties and similar

compounds LiP catalyzes several oxidations in the side chains of lignin and

related compounds (Tien and Kirk 1983) by one-electron abstraction to form L

49


form reactive radicals (Fig 22) (Kersten et al 1985) Also the cleavage of

aromatic ring structures has been reported (Umezawa and Higuchi 1987) LiP

are glycoproteins with molecular weights estimated at 38-46 kDa LiP has been

used to mineralize a variety of recalcitrant aromatic compounds such as three

Fig 22 Generic scheme of the catalytic cycle of peroxidases (adapted from

Wesenberg et al 2003)

and four-ring PAHs (Guumlnther et al 1998) polychlorinated biphenyls (Krcmaacuter

and Ulrich 1998) and dyes (Chivukula et al 1995) 2-Chloro-1

4-dimethoxybenzene a natural metabolite of white rot fungus is reported to act

as a redox mediator in the LiP-catalyzed oxidations (Teunissen et al 1998)

Recently third group of peroxidases versatile peroxidases (VP) has been

invented in species of Pleurotus and Bjerkandera which that can be considered

as a hybrid between MnP and LiP since they can oxidize not only Mn2+ but also

phenolic and nonphenolic aromatic compounds including dyes (Heinfling et al

1998a b) There are many reviews focused on the molecular biology of white rot

50


fungus peroxidases (Martıacutenez 2002 Conesa et al 2002)

ii) Laccase (EC11032)

Laccases are copper containing enzymes belonging to the small group

called as blue oxidase enzymes Laccase also called as the phenol oxidase that

catalyzes the oxidation of several aromatic and inorganic substances

(particularly phenols) with the concomitant reduction of oxygen to water (Duraacuten

et al 2002) (Fig 23) The molecular structure of laccases exhibits four

neighbor copper atoms which are distributed among different binding-sites and

they are classified into three types Copper I II and III which are differentiated

by specific characteristic properties that allow them to play an important role in

the catalytic mechanism of the enzyme (McGuirl and Dooley 1999) The

molecular weight of laccase was observed in the range 60ndash390 kDa

(Reinhammar 1984 Call and Muumlcke 1997) Laccases have been intensively

studied with a focus on their industrial applicability (Yaropolov et al 1994

Bajpai 1999 Gianfreda et al 1999 Rodrıacuteguez et al 1999) molecular genetics

(Cullen 1997 Ong et al 1997 Collins and Dobson 1997) cloning (Hatamoto

et al 1999) and in the degradation of various recalcitrant compounds such as

chlorophenols (Grey et al 1998 Fahr et al 1999) polyaromatic hydrocarbons

(PAHs) (Majcherczyk et al 1998) lignin-related structures (Bourbonnais et al

1996) organophosphorous compounds (Amitai et al 1998) phenols (Bollag et

al 1988 Xu 1996) and last but not least aromatic dyes (Chivukula and

Renganathan 1995 Rodrıacuteguez et al 1999 Kalyani et al 2008 Saratale et al

2009b) Moreover several process using laccases as well as immobilized

laccases have been developed for the treatment of phenolic effluents and

polycyclic aromatic hydrocarbons (Abadulla et al 2000)

51


Fig 23 The catalytic cycle of laccases (adapted from Wesenberg et al 2003)

242 Reductive enzymes

i) Azoreductase

Azoreductases are the enzymes which catalyzes the reductive cleavage of

azo bond (-N=N-) to produce colorless aromatic amine products (Chang et al

2001) The azoreductase were observed in many organisms including the rat

liver enzyme cytochrome P-450 rabbit liver aldehyde oxidase and

azoreductases from the intestinal microbiota (Zbaida and Levine 1990 Stoddart

and Levine 1992) Several studies have been reported bacterial cytoplasmic

azoreductases and suggested the application for the purpose of environmental

biotechnology (Zimmermann et al 1982 Rafii and Cerniglia 1993

Moutaouakkil et al 2003 Maier et al 2004 Ramalho et al 2004)

Azoreductases on the basis of their function are categorized as flavin-dependant

azoreductases (Nakanishi et al 2001 Chen et al 2004 Chen et al 2005) and

flavin-independent azoreductases (Blumel et al 2002 Blumel and Stolz 2003)

52


The flavin-dependent azoreductases are further organized on the basis of their

cofactor NADH only (Nakanishi et al 2001 Chen et al 2004) NADPH only

(Chen et al 2005) or both (Ghosh et al 1992 Wang et al 2007) as these

coenzymes serve as electron donors Based on the primary amino acid level the

classification of azoreductases is found to be difficult hence recently

classification based on the secondary and tertiary amino acid analysis has been

developed (Abraham 2007)

ii) NADPH-DCIP (Dichorophenol indophenol) reductase

NADH-DCIP reductases are marker enzymes of the bacterial and fungal

mixed function oxidase system and take part in the detoxification of xenobiotic

compounds (Bhosale et al 2006 Parshetti et al 2006 Saratale et al 2007a)

Several studies in our laboratory reported this as a marker enzyme for the

reduction of azo bond because in the presence of this enzyme the 2 6

dichlorophenolindophenol (DCIP) accept an electron from NADH to form its

leuco form Orginally DCIP is a blue in color its oxidized form and becomes

colorless when it is reduced (Fig 24)

O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+

Leuco-DCIP (colorless)

Fig 24 Reduction of DCIP to form its leuco form

iii) Riboflavin reductase

Riboflavin reductase has been reported in the degradation of azo dyes

(Russ et al 2000) In this the non-enzymatic reduction of free flavins by

NADPH and NADH is rather slow requires organism to possess a system to

53


catalyze the reaction As a result the enzyme NAD(P)Hflavin oxidoreductase or

flavin reductase are evolved (Ingelman et al 1999) The enzyme flavin

reductase catalyzes the reduction of various flavins that is riboflavin flavin

mononucleotide (FMN) and flavin adenine dinucleotide (FAD) at the expense of

reduced pyridine nucleotides (Spyrou et al 1991) The ability of riboflavin

reductase to act as an azo reductase had been demonstrated the degradation of

scarlet RR and Green HE4BD by the enzyme present in consortium-GR and

Micrococcus glutamicus NCIM-2168 (Saratale et al 2009b and c)

25 Toxicity studies

Variety of synthetic dyestuff released by the textile industries pose a

threat to the environmental safety It is estimated that 10-15 of the dyes is lost

in the effluent during the dyeing process (Robinson et al 2001 Pearce et al

2003) and in the case of reactive azo dyes due to higher solubility up to 50 of

the dye is lost through hydrolysis during the dyeing process which shows

negative aesthetic effect on the wastewater In fact as much as 90 of reactive

dyes could remain unaffected after activated sludge treatment (Patil et al 2008)

The release of textile and dye-house effluent may cause abnormal coloration of

surface waters that creates the problems for both the public and the environment

There are not just artistic problems the greatest environmental concern with the

dyes is their absorption water quality penetration of sunlight and which directly

affects the aquatic flora and fauna In addition the human health impact of dyes

has caused concern for number of years It has been reported that the

contamination of hot chili other spices and baked foods with azo dyes (Calbiani

et al 2004 Mazzetti et al 2004 Wang et al 2007) There is some evidence

that azo dyes have genotoxic effects (Stiborova et al 2002 Stiborova et al

2005 Stiborova et al 2006 An et al 2007) and that ingestion of food products

54


contaminated with dyestuffs could lead to exposure in the human gastrointestinal

tract

Toxicity of azo dyes and their metabolic intermediates has been

investigated by many researchers These toxicity studies include genotoxicity

mutagenicity mortality and carcinogenicity diverge from tests with aquatic

fauna (fish algae bacteria etc) to tests with mammals Recently some research

has been carried out to study the effects of dyestuffs and dye containing effluents

on the activity of both aerobic and anaerobic bacteria in wastewater treatment

systems (Pandey et al 2007) Furthermore the occupational exposure to

dyestuffs of human workers in dye manufacturing and dye utilizing industries

has received attention It was observed that purified form of azo dyes are directly

mutagenic and carcinogenic except for some azo dyes (Brown and DeVito

1993) In mammalian system metabolic activation (reduction) of azo dyes is

mainly carried out by bacteria present in the anaerobic parts of the lower

gastrointestinal tract In addition the liver and the kidneys can also reduce the azo

dyes After azo dye reduction in the intestinal tract and kidney the toxic

aromatic amines are absorbed by the intestine and excreted in the urine The

severe effect of aromatic amines is carcinogenesis especially causes bladder

cancer The mechanism of carcinogenicity includes the formation of acyloxy

amines through N-hydroxylation and N-acetylation of the aromatic amines

followed by O-acylation These acyloxy amines can be converted to nitremium

and carbonium ions that bind to DNA and RNA which induces various kinds of

mutations and resulted into tumor formation (Brown and DeVito 1993) In 1975

and in 1982 the International Agency for Research on Cancer (IARC)

summarized the literature on suspected azo dyes mainly amino-substituted azo

dyes fat-soluble azo dyes and benzidine azo dyes but also a few sulfonated azo

55


dyes (IARC 1975 1982) Most of the dyes on the IARC list were taken out of

production (Brown and DeVito 1993)

Moreover the aromatic amine with benzidine toluene aniline and

naphthalene moieties causes genotoxicity The toxic effect of these amines

generally depends on the structure or location of the dye molecule Some reports

gives strong evidence about the 2-naphthylamine is a carcinogen whereas

1-naphthylamine is much less toxic (Cartwright 1983) Human exposure to azo

dyes occurs through ingestion inhalation or skin contact Recently some studies

shows that Sudan dyes have genotoxic effects (Stiborova et al 2002 Stiborova

et al 2005 Stiborova et al 2006) From available literature it can be

concluded that almost all textile dyes have genotoxic and adverse environmental

effects

Despite the fact that untreated dyeing effluents might cause serious

environmental and health hazards they are being disposed off in water bodies

and this water is being used for an agriculture purpose (Kalyani et al 2008) Use

of untreated and treated dyeing effluents in the agriculture has direct impact on

the fertility of soil Thus it was of concern to assess the phytotoxicity of the dye

before and after degradation Some investigators studied the toxic effect of azo

dyes and their metabolites in terms of germination rate root and plumule length

as well as the enzymatic system responsible for decolorization present in the

plants (Ghodake et al 2008 Kagalkar et al 2009 Saratale et al 2009a) The

results suggest that after microbial mainly bacterial treatment the extract of

degraded metabolites was found to be less toxic than the parent compound The

foregoing results suggest the potential of utilizing bacterial system to decolorize

textile effluent containing a mixture of textile dyes via appropriate bioreactor

operations

56


26 Decolorization and degradation of azo dyes using immobilized cell

system

Several studies reported that immobilized-cell systems which not only

increase the biomass concentration but also enhance the stability mechanical

strength and reusability of the biocatalyst Cell immobilization by entrapment

within natural or synthetic matrices is particularly suitable for bacterial

decolorization of azo dyes since it creates a local anaerobic environment

favorable to oxygen-sensitive decolorization In contrast despite the fact that the

suspended-cell system allows better contact with the substrates it may be less

feasible in practical applications due to the requirement of downstream

solid-liquid separation and the difficulty of achieving a high cell density Due to

these reasons few researchers have reported utilization of immobilized-cell

systems for decolorization of wastewater and most cases have focused on

immobilization of fungal biomass (Chang et al 2001 Chen et al 2005) rather

than bacterial cells which also hold potential for decolorization (Yang et al

1996 Palleria et al 1997) In fact it has been demonstrated that immobilized

microbial systems greatly improve bioreactor efficiency for instance increasing

process stability and tolerance to shock loadings allowing higher treatment

capacity per unit biomass and generating relatively less biological sludge

(Marwaha et al 1998 Zhang et al 1999) In addition biocatalyst

immobilization could significantly increase the entrapped biomass concentration

and thereby reduces the bioreactor volume to satisfy a critical criterion in

practical uses Cell immobilization with gel entrapment holds an extra benefit of

creating a local anaerobic environment which is particularly suitable for

oxygen-sensitive bacterial decolorization (Palleria et al 1997) Therefore it

seems promising to use immobilized cell system to develop decolorization

57


bioprocesses

Considering the overview of the literature the present study was

undertaken to determine the potential of developed consortium-GR (consisting

of Proteus vulgaris NCIM-2027 and Micrococcus glutamicus NCIM-2168) and

individual strains for the degradation of various azo dyes The present work was

accomplished considering the following objectives

27 Objectives of the thesis

1 To design a microbial consortium of efficient microorganisms for the

degradation of Scarlet RR Green HE4BD and Navy Blue HE2R

2 To standardize the physicochemical conditions as well as different carbon

and nitrogen source for the efficient decolorization

3 To use this developed consortium for the decolorization and degradation of

mixture of different industrial dyes

4 To study the nature of enzyme system responsible for the decolorization and

degradation of azo dyes and possible use for co metabolism

5 To study of longetivity of decolorization activity of microorganisms

enzymes and immobilized cells in repeated batch decolorization tests

6 To study the mineralization change in the individual dye and mixture of dyes

during decolorization process by using COD and TOC also to perform the

toxicity studies using phytotoxicity and microbial toxicity study

7 To determine the structural configuration of metabolites formed using

decolorization process by using analytical techniques viz Uv-Vis ADMI

(for mixture of dyes) FTIR HPLC and GCMS

8 To study the metabolic pathway involved in dye degradation by using

enzymatic and analytical results

58


9 To develop the immobilization methods by using different gel matrices and

to study their potential using different azo dyes by optimizing

physicochemical conditions

10 To design a fixed bed reactor (FBR) using calcium alginate immobilized

beads and using agricultural raw material as a biofilm to treat individual and

mixture of various industrial dyes

59


21 Importance of biological treatment relative to physicochemical methods

Together with industrialization awareness towards the environmental

problems arising due to effluent discharge is of a critical importance A dye

house effluent typically contains 06ndash08 g l-1 dye (Gahr et al 1994) Pollution

caused by dye effluent is mainly due to durability of the dyes in the wastewater

(Jadhav et al 2007) Therefore both color creating and the color using industries

are compelled to search for novel physicochemical treatments and technologies

which are directed particularly towards the decolorization of the dyes from the

effluents There are many reports on the use of physicochemical methods for

color removal from dyes containing effluents (Churchley 1994 Vandevivere et

al 1998 Swaminathan et al 2003 Behnajady et al 2004 Golab et al 2005

Lopez-Grimau and Gutierrez 2005 Santos et al 2007 Wang et al 2007) The

various physicalchemical methods such as adsorption chemical precipitation

photolysis chemical oxidation and reduction electrochemical treatment were

used for the removal of dyes from wastewater effluent (Fig 21)

Fig 21 Treatment methods for the removal of dyes from wastewater effluent

211 Physical and chemical methods

Physical method Chemical method

Adsorption Filtration

Reverse osmosis Electrolysis

Ozonation

Microorganisms

Biological method

Enzymes

Coagulation Floculation

Oxidation

TTrreeaattmmeenntt mmeetthhooddss ffoorr tteexxttiillee eefffflluueennttss

12




























13










2005)


















14




























15




2007)
























16




























17




























18




























19



























20


























(Williams 2002)


21




























22



(Pandey et al 2007)

























23




























24


25











Table 21





















68 37 static





Pseudomonas sp SUK1


Kalyani et al 2007

Pseudomonas sp SUK1










26





Chen et al 1999




Dhanve et al 2008



55-100 20-35 NA 8 90 NA Chen et al 2003




Bhatt et al 2005


70 37 NA 24ndash27a 12b

100a

100b












27







NA NA Static

4 6 8

100 100 100




10d

100c

100d










Pseudomonas luteola



28


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59




























13










2005)


















14




























15




2007)
























16




























17




























18




























19



























20


























(Williams 2002)


21




























22



(Pandey et al 2007)

























23




























24


25











Table 21





















68 37 static





Pseudomonas sp SUK1


Kalyani et al 2007

Pseudomonas sp SUK1










26





Chen et al 1999




Dhanve et al 2008



55-100 20-35 NA 8 90 NA Chen et al 2003




Bhatt et al 2005


70 37 NA 24ndash27a 12b

100a

100b












27







NA NA Static

4 6 8

100 100 100




10d

100c

100d










Pseudomonas luteola



28


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59










2005)


















14




























15




2007)
























16




























17




























18




























19



























20


























(Williams 2002)


21




























22



(Pandey et al 2007)

























23




























24


25











Table 21





















68 37 static





Pseudomonas sp SUK1


Kalyani et al 2007

Pseudomonas sp SUK1










26





Chen et al 1999




Dhanve et al 2008



55-100 20-35 NA 8 90 NA Chen et al 2003




Bhatt et al 2005


70 37 NA 24ndash27a 12b

100a

100b












27







NA NA Static

4 6 8

100 100 100




10d

100c

100d










Pseudomonas luteola



28


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59




























15




2007)
























16




























17




























18




























19



























20


























(Williams 2002)


21




























22



(Pandey et al 2007)

























23




























24


25











Table 21





















68 37 static





Pseudomonas sp SUK1


Kalyani et al 2007

Pseudomonas sp SUK1










26





Chen et al 1999




Dhanve et al 2008



55-100 20-35 NA 8 90 NA Chen et al 2003




Bhatt et al 2005


70 37 NA 24ndash27a 12b

100a

100b












27







NA NA Static

4 6 8

100 100 100




10d

100c

100d










Pseudomonas luteola



28


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59




2007)
























16




























17




























18




























19



























20


























(Williams 2002)


21




























22



(Pandey et al 2007)

























23




























24


25











Table 21





















68 37 static





Pseudomonas sp SUK1


Kalyani et al 2007

Pseudomonas sp SUK1










26





Chen et al 1999




Dhanve et al 2008



55-100 20-35 NA 8 90 NA Chen et al 2003




Bhatt et al 2005


70 37 NA 24ndash27a 12b

100a

100b












27







NA NA Static

4 6 8

100 100 100




10d

100c

100d










Pseudomonas luteola



28


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59




























17




























18




























19



























20


























(Williams 2002)


21




























22



(Pandey et al 2007)

























23




























24


25











Table 21





















68 37 static





Pseudomonas sp SUK1


Kalyani et al 2007

Pseudomonas sp SUK1










26





Chen et al 1999




Dhanve et al 2008



55-100 20-35 NA 8 90 NA Chen et al 2003




Bhatt et al 2005


70 37 NA 24ndash27a 12b

100a

100b












27







NA NA Static

4 6 8

100 100 100




10d

100c

100d










Pseudomonas luteola



28


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59




























18




























19



























20


























(Williams 2002)


21




























22



(Pandey et al 2007)

























23




























24


25











Table 21





















68 37 static





Pseudomonas sp SUK1


Kalyani et al 2007

Pseudomonas sp SUK1










26





Chen et al 1999




Dhanve et al 2008



55-100 20-35 NA 8 90 NA Chen et al 2003




Bhatt et al 2005


70 37 NA 24ndash27a 12b

100a

100b












27







NA NA Static

4 6 8

100 100 100




10d

100c

100d










Pseudomonas luteola



28


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59




























19



























20


























(Williams 2002)


21




























22



(Pandey et al 2007)

























23




























24


25











Table 21





















68 37 static





Pseudomonas sp SUK1


Kalyani et al 2007

Pseudomonas sp SUK1










26





Chen et al 1999




Dhanve et al 2008



55-100 20-35 NA 8 90 NA Chen et al 2003




Bhatt et al 2005


70 37 NA 24ndash27a 12b

100a

100b












27







NA NA Static

4 6 8

100 100 100




10d

100c

100d










Pseudomonas luteola



28


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59



























20


























(Williams 2002)


21




























22



(Pandey et al 2007)

























23




























24


25











Table 21





















68 37 static





Pseudomonas sp SUK1


Kalyani et al 2007

Pseudomonas sp SUK1










26





Chen et al 1999




Dhanve et al 2008



55-100 20-35 NA 8 90 NA Chen et al 2003




Bhatt et al 2005


70 37 NA 24ndash27a 12b

100a

100b












27







NA NA Static

4 6 8

100 100 100




10d

100c

100d










Pseudomonas luteola



28


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59


























(Williams 2002)


21




























22



(Pandey et al 2007)

























23




























24


25











Table 21





















68 37 static





Pseudomonas sp SUK1


Kalyani et al 2007

Pseudomonas sp SUK1










26





Chen et al 1999




Dhanve et al 2008



55-100 20-35 NA 8 90 NA Chen et al 2003




Bhatt et al 2005


70 37 NA 24ndash27a 12b

100a

100b












27







NA NA Static

4 6 8

100 100 100




10d

100c

100d










Pseudomonas luteola



28


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59




























22



(Pandey et al 2007)

























23




























24


25











Table 21





















68 37 static





Pseudomonas sp SUK1


Kalyani et al 2007

Pseudomonas sp SUK1










26





Chen et al 1999




Dhanve et al 2008



55-100 20-35 NA 8 90 NA Chen et al 2003




Bhatt et al 2005


70 37 NA 24ndash27a 12b

100a

100b












27







NA NA Static

4 6 8

100 100 100




10d

100c

100d










Pseudomonas luteola



28


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59



(Pandey et al 2007)

























23




























24


25











Table 21





















68 37 static





Pseudomonas sp SUK1


Kalyani et al 2007

Pseudomonas sp SUK1










26





Chen et al 1999




Dhanve et al 2008



55-100 20-35 NA 8 90 NA Chen et al 2003




Bhatt et al 2005


70 37 NA 24ndash27a 12b

100a

100b












27







NA NA Static

4 6 8

100 100 100




10d

100c

100d










Pseudomonas luteola



28


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59




























24


25











Table 21





















68 37 static





Pseudomonas sp SUK1


Kalyani et al 2007

Pseudomonas sp SUK1










26





Chen et al 1999




Dhanve et al 2008



55-100 20-35 NA 8 90 NA Chen et al 2003




Bhatt et al 2005


70 37 NA 24ndash27a 12b

100a

100b












27







NA NA Static

4 6 8

100 100 100




10d

100c

100d










Pseudomonas luteola



28


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59


25











Table 21





















68 37 static





Pseudomonas sp SUK1


Kalyani et al 2007

Pseudomonas sp SUK1










26





Chen et al 1999




Dhanve et al 2008



55-100 20-35 NA 8 90 NA Chen et al 2003




Bhatt et al 2005


70 37 NA 24ndash27a 12b

100a

100b












27







NA NA Static

4 6 8

100 100 100




10d

100c

100d










Pseudomonas luteola



28


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59









68 37 static





Pseudomonas sp SUK1


Kalyani et al 2007

Pseudomonas sp SUK1










26





Chen et al 1999




Dhanve et al 2008



55-100 20-35 NA 8 90 NA Chen et al 2003




Bhatt et al 2005


70 37 NA 24ndash27a 12b

100a

100b












27







NA NA Static

4 6 8

100 100 100




10d

100c

100d










Pseudomonas luteola



28


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59





Chen et al 1999




Dhanve et al 2008



55-100 20-35 NA 8 90 NA Chen et al 2003




Bhatt et al 2005


70 37 NA 24ndash27a 12b

100a

100b












27







NA NA Static

4 6 8

100 100 100




10d

100c

100d










Pseudomonas luteola



28


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59







NA NA Static

4 6 8

100 100 100




10d

100c

100d










Pseudomonas luteola



28


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59


dyes (100 mg1-1)






NA 24 50-90





NA 20 min


Yatome et al 1991



NA 24 100


Sphingomonas sp BN6



Pseudomonas luteola




Sphingomonas sp BN6





29


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59


(102 to 75 mg1-1)

Pseudomonas luteola









70 37 static

24

100











70 37 static

72

100





14 9

100 100



30




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59




70 37 static

3 100 Reduction




68 37 static







(50 mg1-1 each)




4-9 20-40 NA 24 991 NA Fang et al 2004



70 35 100 rpm 24 24 24

78 99 94


31




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59




24 24

99 82



















32




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59




(100 mg1-1) batch



cancerogenus






Consortium of




33











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59











Knapp et al (1995)










34





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59





24 24

789 90

NA

Supaka 2004


















35






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59






NA 40 30

95 90

NA Yoo et al 2001






36






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59






















37


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59


38





NA 1125 1349 mg l-1 d-1

609




















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59















Reaction mechanism











39




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59




























40















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59















means

231 Oxygen












41


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59


























42


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59


232 Temperature















233 pH











43




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59




























44












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59












235 Dye structure














45
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59
















236 Electron donor












46














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59














237 Redox mediator














47








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59








238 Redox potential




















48


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59


















2004)










49

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59

















50



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59



























51




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59




i) Azoreductase













52


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59


















O N OCl

Cl

Na+

DCIP (blue)

[H]

[H]

+2 Red

-2 OxidNH OH

Cl

Cl

ONa+







53










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59










25 Toxicity studies


















54



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59



tract

























55













effects














operations

56



system

























57


bioprocesses

























58








59













effects














operations

56



system

























57


bioprocesses

























58








59



system

























57


bioprocesses

























58








59


bioprocesses

























58








59








59

Documents

Review of literature - INFLIBNETshodhganga.inflibnet.ac.in/bitstream/10603/4093/9/09... · 2015-12-04 · Review of literature In advanced countries, the coagulation–flocculation