Anaerobic treatment of distillery spent wash – A study on upflow anaerobic fixed film bioreactor

Available online at www.sciencedirect.com

Bioresource Technology 99 (2008) 4621–4626

Anaerobic treatment of distillery spent wash – A study on upflow anaerobic fixed film bioreactor Bhavik K. Acharya, Sarayu Mohana, Datta Madamwar

*

BRD School of Biosciences, Sardar Patel Maidan, Vadtal Road, Sattelite Campus, P. Box No. 39, Sardar Patel University, Vallabh Vidyanagar 388120, Gujarat, India Received 1 November 2006; received in revised form 27 April 2007; accepted 15 June 2007 Available online 31 August 2007

Abstract Anaerobic digestion of wastewater from a distillery industry having very high COD (1,10,000–1,90,000 mg/L) and BOD (50,000– 60,000 mg/L) was studied in a continuously fed, up flow fixed film column reactor using different support materials such as charcoal, coconut coir and nylon fibers under varying hydraulic retention time and organic loading rates. The seed consortium was prepared by enrichment with distillery spent wash in a conventional type reactor having working capacity of 3 L and was used for charging the anaerobic column reactor. Amongst the various support materials studied the reactor having coconut coir could treat distillery spent wash at 8 d hydraulic retention time with organic loading rate of 23.25 kg COD m3 d1 leading to 64% COD reduction with biogas production of 7.2 m3 m3 d1 having high methane yield without any pretreatment or neutralization of the distillery spent wash. This study indicates fixed film biomethanation of distillery spent wash using coconut coir as the support material appears to be a cost effective and promising technology for mitigating the problems caused by distillery effluent. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Distillery spent wash; Anaerobic fixed film bioreactor; Charcoal; Coconut coir; Nylon fibers

1. Introduction Distillery industries in India pose a very serious threat to the environment because of the large volume of wastewater they generate which contains significant amount of recalcitrant compounds. Distillery spent wash is considered as a very high strength wastewater having very high COD and BOD with low pH and dark brown color (Goel and Chandra, 2003). The pollution caused by the disposal of untreated or inadequately treated wastewater into fresh and marine water bodies is gradually becoming a major hazard to aquatic organisms. Bioremediation of distillery spent wash by anaerobic digestion is an attractive primary treatment due to its reputation as a low cost, environment * Corresponding author. Tel.: +91 2692 234402; fax: +91 2692 236475/ 237258. E-mail addresses: [email protected] (B.K. Acharya), datta_ [email protected] (D. Madamwar).

0960-8524/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2007.06.060

friendly and socio economically acceptable technology. The anaerobic digestion is particularly suitable for winery and distillery waste water because their COD/N/P ratio is unbalanced for aerobic treatments which need phosphorus and nitrogen addition (Moletta, 2005). Anaerobic digestion of biodegradable wastes involves a large spectrum of bacteria of which three main groups are distinguishable. The first group comprises fermenting bacteria which perform hydrolysis and acidogenesis. Acetogenic bacteria constitute the second group and are responsible for breaking down the products of the acidification step to form acetate. The third group involves methanogenic bacteria which convert acetate or carbon dioxide and hydrogen into methane (Kansal et al., 1998). All modern high rate biomethanation processes are based on the concept of retaining high volume of viable biomass by some mode of bacterial sludge immobilization. It can be very well done by entrapment of sludge aggregates between packing material supplied to the reactor,

4622

B.K. Acharya et al. / Bioresource Technology 99 (2008) 4621–4626

e.g. down flow anaerobic reactor and up flow anaerobic reactor (Rajeshwari et al., 2000). The fixed film reactors offer distinct advantages over other anaerobic systems such as simplicity of construction, elimination of mechanical mixing, better stability at higher loading rates and capability to withstand large toxic shock loads. The solid support filling within reactor is the most important component of an anaerobic fixed film reactor. Some ideal characteristics of the packing material are high porosity, large surface area, adequate surface properties for adherence light weight and economical (Agamuthu, 1999). The main objective of the present study was to investigate the role of an appropriate support material which would allow more bacterial biomass to sustain in the reactor and thus leading to efficient biodegradation of distillery spent wash.

B

G C

2. Methods

D

E

A

H1

H2

F

2.1. Substrate Distillery spent wash was collected from a distillery situated at Ankleshwar, GIDC, Gujarat, India. The characteristics of the wastewater are given in Table 1. 2.2. Experimental set-up

Fig. 1. Schematic diagram of up flow anaerobic fixed film bioreactor: (A) anaerobic fixed film reactor; (B) packing material; (C) untreated wastewater; (D) treated effluent; (E) peristaltic pump; (F) rubber bungs; (G) Teflon plate; (H1 and H2) water displacement units.

slurry were used as inoculum along with distillery spent wash.

Laboratory scale anaerobic upflow fixed film glass column reactors (Fig. 1) were used in the present study. Each reactor was constructed using a glass column having following specifications. Reactor height: 4800 , media height: 4000 , inner diameter: 4.5 cm, total volume: 2 L and working volume: 1 L. Reactors were packed with different packing materials namely charcoal, coconut coir and nylon fibers. 2.3. Enrichment of anaerobic consortia Anaerobic seed consortium was prepared by enrichment in conventional type reactors having 3 L working volume. Anaerobic sludge from an ongoing reactor and cattle dung Table 1 Characteristics of distillery spent wash Parameters

Values of distillery spent wash

pH BOD5 (mg L1) COD (mg L1) Total solid (TS) (mg L1) Total volatile solid (TVS) (mg L1) Total suspended solid (TSS) (mg L1) Total dissolved solids (TDS) (mg L1) Chlorides (mg L1) Phenols (mg L1) Sulfate (mg L1) Phosphate (mg L1) Total nitrogen (mg L1)

3.0–4.5 50,000–60,000 1,10,000–1,90,000 1,10,000–1,90,000 80,000–1,20,000 13,000–15,000 90,000–1,50,000 8000–8500 8000–10,000 7500–9000 2500–2700 5000–7000

2.4. Start up of fixed film reactors Upflow anaerobic fixed film reactors were charged with the enriched anaerobic culture from the conventional type of reactors as inoculum and biofilm was allowed to develop by incubating at 37 °C for 35–40 d. During incubation period facultative anaerobes utilized the organic matter present in the substrate and created anaerobic conditions for strict anaerobic bacteria. Biofilm development was assessed by gas production and visual observation in change of color. Initially biogas production was low because of acclimatization and adaptation of the bacteria on support materials. After the establishment of all the group of bacteria biogas production increased, and as the organic matter present in the substrate depleted biogas production decreased gradually. Then the effluent was slowly replaced with distillery spent wash of pH 4.5 without neutralization and any pretreatment. Initially all the reactors were operated at HRT of 30 d for at least three retention times after reaching steady state condition. Subsequently HRT was decreased and accordingly OLR was increased gradually and reactors operated at 20 d, 15 d, 10 d, 8 d and 6 d. All the reactors were allowed to reach to steady state condition. They were run at least for 3–4 RT after reaching steady state condition. Steady state condition was judged by stable gas production and constant COD and BOD of the effluent (Patel and Madamwar, 2002). All the reactors

B.K. Acharya et al. / Bioresource Technology 99 (2008) 4621–4626

were operated on a continuous basis at the desired retention time and spent wash was fed into the reactor in an upward direction at the required rate using peristaltic pump (Gilson Minipuls 3, France). 2.5. Analytical methods Biogas production was measured by the displacement of acidified water (pH 2–2.5). Gas composition was determined with gas liquid chromatograph (Sigma, Baroda (India) Model M505) equipped with 2 m stainless steel column packed with Porapak R (80–100 mesh) at 50 °C and a thermal conductivity detector, nitrogen was served as a carrier gas at a flow rate of 30 mL min1. The injector and detector temperatures were kept at 125 °C. Feed and reactor effluent samples were routinely analyzed for pH, O/R potential, COD, BOD, volatile fatty acids, alkalinity, total solids, total dissolved solids, total volatile solids, total nitrogen, sulphates and phosphates according to Standard Methods for Examination of Water and Wastewater (APHA, 1995). COD was measured using Hach DR 2010 spectrophotometer and Hach COD reactor following the instructions for the Hach higher range test. Dissolved oxygen for BOD was measured by YSI 5100 Dissolved Oxygen Meter. Volatile Fatty Acids were determined using the same gas liquid chromatograph equipped with flame ionization detector and 3 mm diameter, 3 m stainless still column packed with 10% FFAP (Sigma, Baroda, India.). Nitrogen served as the carrier gas at a flow rate of 30 mL min1, column temperature was kept at 180 °C. The injector and detector temperature were 200 °C and 250 °C, respectively. 3. Results and discussion 3.1. Effect of packing material Considerable work has been reported on biomethanation using up flow anaerobic reactors with a variety of support media having porous and non porous structures (Seth et al., 1995). A porous inert media enhances biofilm development considerably as compared to more smooth media (Patel and Madamwar, 2002). The support material has always had a large influence on the start up and on the effi-

4623

ciency of the process because the initial biomass of film may be of major importance for further biofilm growth and stability. Our results also differ significantly amongst the three reactors as the packing material varied. During initial incubation period the biofilm development was visually more detectable on, coconut coir and charcoal but on nylon fibers the thickness of the biofilm was very poor. This difference in biofilm development may be attributed to the hydrophobic nature and smoothness of the material (nylon fibers) that prevented the substrate from reaching the inner surfaces. Predominance of organisms in the biofilm is influence by porosity and surface area of support material. High porosity and higher surface area of coconut coir help methanogenic bacteria to predominate in the biofilm along with acidogenic bacteria and favour efficient biomethanation process. This was supported by best performance of coconut coir bedded bioreactor as indicated by efficient COD and BOD reduction, higher gas production with high methane yield even at lower retention time. However, reactor could not be operated below 20 d HRT when bedded with nylon fibers. 3.2. Effect of OLR and HRT on COD and BOD reduction The performance of the wastewater treatment system can be related directly to the COD removal efficiency achieved in the process (Wolmarans and de Villiers, 2002). There have been few investigations especially devoted to the stability of anaerobic fixed film process under hydraulic shock loadings (Chua et al., 1997). Tables 2–4 as well as Figs. 2–4 summarize the steady state performance of anaerobic up flow fixed film reactors with different packing materials namely charcoal, coconut coir and nylon fibers operated at 37 °C in a temperature controlled chamber under different organic loadings. All reactors were initially operated at an HRT of 30 d by continuous feeding of distillery spent wash without any dilution or neutralization. In order to study the effect of OLR and HRT, flow rates were increased in a stepwise manner i.e., HRT from 30 to 20 d then 15, 12, 10, 8 and 6 d. After each change in HRT the reactors were allowed to reach steady state conditions, and they were allowed to run at each HRT for at least 3–4 cycles. The higher

Table 2 Values of an up flow anaerobic fixed film reactor effluent operated at 37 °C with charcoal as packing material at varying hydraulic retention times under steady state conditions HRT (d) OLR (kg COD m3 d1) TS (g L1) TDS (g L1) TVS (g L1) O/R potential (mV) Sulfates (mg L1) Phosphates (mg L1) Nitrogen (mg L1) TVA (mg L1)

30 6.2 43.50 ± 1.50 14.0 ± 1.05 38.0 ± 1.50 065 ± 002 6500 ± 90.55 – – ND

20 9.3 52.55 ± 1.85 18.0 ± 2.28 47.0 ± 3.25 064 ± 002 5979.15 ± 94.12 2350 ± 80.80 3250.75 ± 50.80 ND

15 12.4 57.5 ± 2.25 22.5 ± 2.50 51.0 ± 4.25 060 ± 003 6000 ± 73.75 2585.66 ± 94.62 3200.25 ± 50.40 ND

12 15.5 70.5 ± 2.15 26.5 ± 3.55 55.5 ± 3.80 067 ± 003 4025.15 ± 100.10 2465.75 ± 35.50 2800.50 ± 30.80 850 ± 50.40

10 18.6 110.5 ± 2.20 48.0 ± 3.20 63.0 ± 4.25 069 ± 002 3700 ± 102.50 2450.85 ± 50.55 2650.80 ± 30.75 1150 ± 65.40

8 23.25 125.10 ± 3.50 60.5 ± 3.80 70.5 ± 4.20 055 ± 005 3750 ± 100.85 2460.75 ± 35.75 2600.50 ± 40.45 6350 ± 102.25

6 31 – – – – – – –

4624

B.K. Acharya et al. / Bioresource Technology 99 (2008) 4621–4626

Table 3 Values of an up flow anaerobic fixed film reactor effluent operated at 37 °C with coconut coir as packing material at varying hydraulic retention times under steady state conditions HRT (d) OLR (kg COD m3 d1) TS (g L1) TDS (g L1) TVS (g L1) O/R potential (mV) Sulfates (mg L1) Phosphates (mg L1) Nitrogen (mg L1) TVA (mg L1)

30 6.2 42.0 ± 3.50 13.8 ± 2.50 36.5 ± 2.50 065 ± 002 – – – –

20 9.3 50.8 ± 3.80 15.5 ± 2.85 43.8 ± 2.75 061 ± 002 6000 ± 40.80 2350 ± 50.55 2450 ± 40.40 ND

15 12.4 54.2 ± 4.05 18.7 ± 2.70 49.2 ± 3.25 062 ± 003 5050 ± 45.25 2380 ± 30.80 2480 ± 40.45 ND

12 15.5 65.5 ± 5.10 24.8 ± 3.05 54.5 ± 3.50 065 ± 003 6150 ± 50.90 2480 ± 60.50 2300 ± 40.85 ND

10 18.6 101.2 ± 10.10 49.8 ± 4.05 59.9 ± 4.55 067 ± 003 5000 ± 40.50 2450 ± 70.60 2350 ± 30.35 ND

8 23.25 106.5 ± 10.15 47.5 ± 5.50 62.5 ± 5.00 097 ± 002 4750 ± 25.90 2490 ± 50.70 1156 ± 35.85 750 ± 40.85

6 31 123 ± 11.50 55.8 ± 5.50 65.5 ± 6.15 076 ± 003 4500 ± 50.25 2380 ± 50.75 1140 ± 40.45 1200 ± 80.55

Table 4 Values of an up flow anaerobic fixed film reactor effluent operated at 37 °C with nylon fibers as packing material at varying hydraulic retention times under steady state conditions 30 6.2 70.0 ± 5.85 59.5 ± 6.75 60.05 ± 4.50 060 ± 010 4500.85 ± 120.25 2350.50 ± 95.75 – 1250 ± 50.55

20 9.3 123.6 ± 30.50 101.8 ± 32.75 110.8 ± 20.75 +110 ± 005 – – – –

100 80

60

60

40

40

20

20

0

0 0

5

10

OLR

15

20

25

30

35

-1 (kgCODm-3d )

Fig. 2. Effect of OLR on % COD reduction and % BOD reduction. %COD reduction: (j) charcoal; () coconut coir; (m) nylon fibers; % BOD reduction: (h) charcoal; (e) coconut coir; (4) nylon fibers.

the HRTs less the time required for reaching the steady state and the lower the HRTs the more the time required to reach the steady state. The steady state data revealed that charcoal and coconut coir provided good support for biomass compared to nylon fibers. Reactor having charcoal as packing material was able to reduce about 80% COD and 88% BOD of the spent wash at 30 d HRT and OLR of 6.2 kg COD m3 d1 with total gas production of 2.4 m3 m3 d1 with high methane yield. At each change in HRT and OLR, COD as well as BOD reduction decreased, due to the higher organic load applied at each stage, total gas production increased due to the faster metabolic rate of the organisms. It is shown that 60% COD reduction and 73% BOD reduction was observed with

Total gas production -1 (m3mm-3d )

80

12 15.5 – – – – – – – –

10 18.6 – – – – – – – –

8 23.25 – – – – – – – –

6 31 – – – – – – –

5

8

% BOD reduction

% COD reduction

100

15 12.4 – – – – – – – –

4

6

3 4 2 2

Methane yield -1 (m3m-3m )

HRT (d) OLR (kg COD m3 d1) TS (g L1) TDS (g L1) TVS (g L1) O/R potential (mV) Sulfates (mg L1) Phosphates (mg L1) Nitrogen (mg L1) TVA (mg L1)

1

0

0 0

5

10

15

20

25

30

35

-1

OLR (kgCODm-3d ) Fig. 3. Effect of OLR on total gas production and methane yield. Total gas production: (j) charcoal; () coconut coir; (m) nylon fibers; methane yield: (h) charcoal; (e) coconut coir; (4) nylon fibers.

gas production of 6.2 m3 m3 d1 at 12 d HRT in the reactor having charcoal as packing material. More disturbances were observed at 10 d HRT and 8 d HRT. COD reduction was 50% at 10 d HRT and at 8 d HRT it decreased and reached to only 16% with gas production of 0.5 m3 m3 d1. The performance of the reactor with coconut coir was much better than with charcoal, at 30 d HRT with OLR of 6.2 kg COD m3 d1 COD and BOD reduction were 80% and 89%, respectively, and gas production was 2.9 m3 m3 d1. In this case also COD and BOD reduction decreased with increase in OLR but more stability was observed, and no noticeable disturbance occurred in the system. More than 60% COD and 67% BOD reduction

B.K. Acharya et al. / Bioresource Technology 99 (2008) 4621–4626 10

9000 7500

6

pH

Alkalinity mgL

-1

8

6000 4500

4625

and coconut coir respectively. Solid removal efficiency was very poor in reactor having nylon fibers. About 3– 3.5% non volatile matter found in the reactors during the study which indicates very high amount of metals present in the effluent. At lower HRTs more solids were found in the effluent due to the washout of the biofilm.

4 3000 2

1500 0

0 0

5

10

15

20

25

30

35

-1

OLR kgCODm-3d

Fig. 4. Effect of OLR on alkalinity and pH. Alkalinity: (j) charcoal; (r) coconut coir; (m) nylon fibers; pH: (h) charcoal; (e) coconut coir; (4) nylon fibers.

were observed at 8 d HRT with gas production of 7.25 m3 m3 d1. At 6 d HRT OLR was increased to 31 kg COD m3 d1 but COD reduction decreased to 50% and gas production was also decreased to 3.5 m3 m3 d1 (Figs. 2 and 3). Kalyuzhnyi et al. (2005) studied biological treatment of baker’s yeast wastewater in UASB reactor and reported 50% COD reduction at OLR of 16 kg COD m3 d1. These result shows that our reactor showed same COD reduction at almost double organic load. On observing the performance of the reactor packed with nylon fibers, it can be concluded that the reactor was not stable even at high HRT. At 30 d HRT 62% COD and 68% BOD reduction was observed with gas production of 1 m3 m3 d1, and drastic disturbances were observed when HRT was decreased to 20 d as COD and BOD reduction decreased to 30% with gas production of 0.2 m3 m3 d1. Trnovec and Britz (1998), Gangagni Rao et al. (2004), Perez-Garcia et al. (2005) have reported optimum conditions for biomethanation of distillery spent wash to be between OLR of 8 and 10.5 kg COD m3 d1 and on further increasing the OLR, hydraulic shock loading conditions would result with sharp drop in methanogenic activity. In our study better performance was observed in terms of the, removal of COD, BOD and biogas production against OLR applied. The reactor with coconut coir could withstand much higher hydraulic and organic loadings. This may be due to its physical characteristics, which makes it a better support material for biomass development and attachment. 3.3. Effect of OLR on solid removal Distillery spent wash contains very high amount of solids and the major part of it as dissolved solids. In reactor with charcoal and coconut coir as packing material, at 30 d HRT, TS of the effluent were 43.50 g L1 and 42.0 g L1, respectively, but as the loading rate increased solid removal decreased and at 8 d HRT, TS were 125.10 g L1 and 106.5 g L1 in reactor with charcoal

3.4. pH, alkalinity and volatile acids The anaerobic digestion process is known to be extremely sensitive to pH and optimum operational pH range is 6.0–8.0. It is known that methanogenesis appears to be an alkalizing step, as it consumes hydrogen and H3O+ ions (Patel and Madamwar, 2000). During the course of study, in all the reactors pH remained between 8.0 and 8.5 except the critical HRT i.e., in reactor having charcoal pH decreased to 6.5 at 8 d HRT due to the accumulation of acids and in case of reactor with nylon fibers pH drop was observed during 20 d HRT (Fig. 4). Data show that the reactors with charcoal and coconut coir provided better buffering capacity (from the data of alkalinity) in comparison to the reactor having nylon fibers. In reactors with charcoal and coconut coir, alkalinity was in the range of 6000–8000 mg L1. Akalinity decreased to 1500 mg L1 at 8 d HRT due to the accumulation of volatile acids and washout of methanogenic population in reactor with charcoal (Fig. 3). The reactor with nylon fibers showed very poor buffering capacity and the reactor became acidic at 20 d HRT with OLR of 9.3 kg COD m3 d1. Accumulation of VFA was not observed at higher HRT in reactors except reactor with nylon fibers. Little amount of VFA was observed at 12 d HRT but it did not affect the reactor condition and pH was also stable in reactor packed with charcoal. At 8 d HRT, VFA accumulation was observed and VFA concentration was 6350 mg L1 with decrease in pH to 6.5. More buffering capacity was observed in reactor having coconut coir due to the high amount of retained biomass. No VFA accumulation was observed till 8 d HRT due to the high buffering capacity. With nylon fibers very little buffering capacity was observed as results shows that even at higher HRT of 30 d VFA concentration was 1000 mg L1 and at 20 d HRT VFA accumulation was so high that pH of the reactor dropped to 5.0, resulting in the failure of the reactor. 3.5. Sulfates, phosphorus and nitrogen Biological treatment of sulfate rich wastewater was rather unpopular because of the production of H2S under anaerobic conditions. Under anaerobic conditions, sulfate reducing bacteria (SRB) use sulfate as a terminal electron acceptor for the degradation of organic compounds and hydrogen. In the presence of sulfate, methanogenic bacteria compete with SRB for the available substrates. The outcome of this competition is important as it will determine to what extent sulphide and methane, the end products

4626

B.K. Acharya et al. / Bioresource Technology 99 (2008) 4621–4626

of the anaerobic mineralization processes, will be produced (Hulshoff Pol et al., 1998). In the present study sulfate reduction was not observed at higher HRTs and the reactors showed higher methanogenic activity from 30 d HRT (data of methane yield from Tables 2–4). In reactor having charcoal, sulfate concentration was 6500 mg L1 at 20 d HRT and at 8 d HRT more sulfate reduction was observed because of more acetate concentration in the reactor, same is the case with coconut coir also, and more sulfate reduction was observed at lower HRT (Table 3). Hulshoff Pol et al. (1998) reported that sulfate emission is not a direct threat for the environment as sulfate is a chemically inert, non volatile and non toxic compound. In reactor with nylon fibers more sulfate reduction was observed even at higher HRT mainly due the less methanogenic activity and more concentration of VFAs. Phosphorus concentration is a very important parameter in wastewater treatment as it is in excess; it could be responsible for eutrophication. Biological phosphorus removal can be possible when the biomass is subjected alternatively to aerobic and anaerobic conditions. Under anaerobic conditions the microorganisms will first liberate phosphate to the liquid phase (Callado and Foresti, 2001). In our study also phosphate tends to increase in compare to the phosphate concentration in the influent but there was no significant increase or decrease and no specific trend was observed. Total nitrogen in reactor having charcoal was 3250 mg L1 at 20 d HRT and it was reduced at each change and concentration was 1480 mg L1 at 8 d HRT. With coconut coir also nitrogen was decreased with each change in HRT and at 6 d HRT it was 1140 mg L1. This can be due to the denitrification process in anaerobic conditions, as both denitrification of oxidized nitrogen and methanogenic degradation occurs simultaneously in the anaerobic fixed film bioreactor (Pozo and Diez, 2003). It was observed that during reactor failure there was significant sloughing of biofilm from reactor having nylon fibers as support material, but comparably less with charcoal and coconut coir. 4. Conclusion Amongst the packing materials studied, coconut coir showed the best results in terms of biogas and methane yield with highest consistency of COD removal, and pH of the effluent. Reactor packed with coconut coir could retain methanogenic biomass and could be operated at short HRT of 6 d with OLR of 31 kg COD m3 d1 of distillery spent without any dilution or neutralization. This has provided a new concept of subjecting very high strength distillery spent wash for biomethanation using upflow fixed film anaerobic bioreactor employing coconut coir as packing material under high organic loading. The

post-methanation effluent still needs to be treated to meet the pollution control standards. References Agamuthu, A., 1999. Specific biogas production and role of packing medium in the treatment of rubber thread manufacturing industry wastewater. Bioprocess Engineering 21, 151–155. APHA, 1995. Standard Methods for the Examination of Water and Wastewater, 19th ed. American Public Health Association, New York. Callado, N.H., Foresti, E., 2001. Removal of organic carbon, nitrogen and phosphorus in sequential batch reactors integrating the aerobic/ anaerobic processes. Water Science and Technology 44, 363–370. Chua, H., Hu, F.W., Yu, F.H.P., Cheung, L.W.M., 1997. Responses of an anaerobic fixed film reactor to hydraulic shock loadings. Bioresource Technology 61, 79–83. Gangagni Rao, A., Venkata Naidu, G., Krishna Prasad, K., Chandrasekhar Rao, N., Venkata Mohan, S., Jetty, A., Sarma, P.N., 2004. Anaerobic treatment of wastewater with high suspended solids from a bulk drug industry using fixed film reactor (AFFR). Bioresource Technology 93, 241–247. Goel, P.K., Chandra, R., 2003. Distillery effluent treatment by methane production in India. In: Advances in Industrial Wastewater Treatment. ABD Publishers, Jaipur, India, pp. 164–179. Hulshoff Pol, W.L., Lens, L., Piet, N., Stams, M., Alfons, J., Lettinga, G., 1998. Anaerobic Treatment of sulphate rich wastewaters. Biodegradation 9, 213–224. Kalyuzhnyi, S., Gladchenko, M., Starostina, E., Shcherbakov, S., Versprille, B., 2005. Integrated biological and physico-chemical treatment of baker’s yeast wastewater. Water Science and Technology 52, 273–280. Kansal, A., Rajeshwari, K.V., Balakrishnan, M., Lata, K., Kishore, N.V.V., 1998. Anaerobic digestion technologies for energy recovery from industrial wastewater – a study in Indian context. TERI Information Monitor on Environmental Science 3, 67–75. Moletta, R., 2005. Winery and distillery wastewater treatment by anaerobic digestion. Water Science and Technology 51, 137–144. Patel, H., Madamwar, D., 2000. Biomethanation of low pH petrochemical wastewater using up-flow fixed film anaerobic bioreactors. World Journal of Microbiology and Biotechnology 16, 69–75. Patel, H., Madamwar, D., 2002. Effects of temperatures and organic loading rates on biomethanation of acidic petrochemical wastewater using an anaerobic upflow fixed-film reactor. Bioresource Technology 82, 65–71. Perez-Garcia, M., Romero-Garcia, I.L., Rodriguez-Cano, R., SalesMarquez, D., 2005. Effect of the pH influent condition in fixed-film reactors for anaerobic thermopillic treatment of wine-distillery wastewater. Water Sciences and Technology 51, 183–189. Pozo, D.R., Diez, V., 2003. Organic matter removal in combined anaerobic – aerobic fixed film bioreactor. Water Research 37, 3561– 3568. Rajeshwari, V.K., Balakrishnan, M., Kansal, A., Lata, K., Kishore, N.V.V., 2000. State of the art of anaerobic digestion technology for industrial wastewater treatment. Renewable and Sustainable Energy Reviews 4, 135–156. Seth, R., Goyal, S.K., Handa, B.K., 1995. Fixed film biomethanation of distillery spent wash using low cost porous media. Resources, Conservation and Recycling 14, 79–89. Trnovec, W., Britz, J.T., 1998. Influence of organic loading rate and hydraulic retention time on efficiency of a UASB bioreactor treating a canning factory effluent. Water SA 24, 1147–1152. Wolmarans, B., de Villiers, H.G., 2002. Start-up of a UASB effluent treatment plant on distillery wastewater. Water SA 28, 63–68.