5.0 Experimental methodology for the treatment of dye. The sludge which is used for the treatment of dye manufacturing

Transcription

1 5.0 Experimental methodology for the treatment of dye intermediate wastewater by using UASB reactors 5.1 Inoculum The sludge which is used for the treatment of dye manufacturing wastewater was procured from Slaughter house, Rudraram, medak, Hyderabad. The characteristics of physico-chemical analysis of dye manufacturing wastewater was done by using Standard methods (APHA, 2000). The characteristics of wastewater was given in Table 5.2.

2 5.2 The characteristics of sewage which is used for the startup of the reactor: S.NO parameter Concentration (mg/l) 1 ph Electrical conductivity 190μ seimens 3 Alkalinity Chemical oxygen demand (COD) Biochemical oxygen demand (BOD) Sulphates 55 7 Nitrates 15 8 phosphates Total solids Total dissolved solids Volatile fatty acids Total suspended solids 274 *All the values are expressed as mg/l except ph and EC

3 5.3 The characteristics of dye wastewater: The wastewater which was procured from JETL, Hyderabad. The characteristics of wastewater is as follows S.No Parameter Concentration (mg/l) 1. ph Electrical conductivity 6550μ seimens 3. Alkalinity Chlorides Chemical oxygen demand Biochemical oxygen demand Colour (O.D at 610nm) Ammonical nitrogen Total solids Total dissolved solids Total suspended solids Volatile suspended solids *All the values are expressed as mg/l except ph and EC

4 5.0 Biodegradation of phenolic compounds by using UASB reactor 5.1 Acclimation of UASB reactors with 4C-2-NP, 2C-4-NP, 2C-5-MP The stabilization of reactors for treating phenolic compounds containing waste waters took almost two hundread days with 30mg/l of influent phenolic compounds respectively. During this period, the compound reduction and COD reduction and gas production was monitored and given in the figures (Figure 2-10). From these results we had observed that at each increment of the phenolic compound concentration, the compound reduction was decreased from 90% to 60% and at the end of the acclimatization period gradually it was increased to 90%. The above experiments showed that after 90 days of the operational period, the increase in concentration to 15 mg/l of the 4c-2np inhibited the reactor performance. When the concentration was increased to 20 mg/l, the reactor was stabilized and showed the best treatment performance. The effluent of the UASB reactor contains 1.6 mg/l and 2.9 mg/l with two different inlet 4C2NP concentration. When the reactors reached to end of the acclimatization period, the removal efficiency of 4C2NP was 91%. 94% 2C-5-MP removal has been observed up to 140 days in 2C-5-MP fed reactor and also the 2C-5-MP percentage removal in the last stage of acclimatization in reactors was 91%. Figure 8,9 and 10 shows that total biogas production during the acclimatization with 4C-2-NP, 2C-4-NP and

5 2C-5-MP in UASB reactor by comparing with control reactor. that at each increment of the phenolic compound concentration, the 90% of the reactor was stabilized and showed gradually it was increased to 90%. The treatment experiments showed that concentration. When the reactors days of the operational decreased from period, the increase in the reactor performance. When the removal efficiency % and at the to 60% acclimatization performance. The effluent of above reached after 90 period l with two different inlet 4C2NP to, the of the acclimatization period concentration to 15 mg/l end concentration was increased to 20 mg/l, the the best compound reduction was the UASB reactor contains 1.6 mg/l and 2.9 mg/ end of the 4c-2np inhibited of 4C2NP was 91%. 94% 2C-5-MP removal. The biogas production has been increased from 0.7 l/d to 4.5 l/d. This indicates that the compound is converted in to biogas. The methane percentages in biogas was varied between 65-72% in all the UASB reactors. These values are similar to that of Partha Sarathy Majumder and Gupta [26].

6 Figure 2 : Removal of 2C-4-NP profile in R3 reactor during the acclimation period

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8 Figure 3: Removal of 4C-2-NP profile in R2 reactor during the acclimation period Figure 4: % of 2C-5-MP removal efficiency at startup of the reactor in 2C- 4-NP fed reactor

9 Figure 5: % of COD removal efficiency at startup of the reactor in 2C-4- NP fed reactor

10 Figure 6: % of COD remocal efficiency at startup of the reactor in 2C-4- NP fed reactor

11 Figure 7: % of COD removal efficiency at startup of the reactor in 2C-5- MP fed reactor

12 Figure 8 : Biogas production in UASB reactor during the startup of the reactor in R1 and R3

13 Figure 9 : Biogas production in UASB reactor during the startup of the reactor in R1 and R4

14 Figure 10 : Biogas production in UASB reactor during the startup of the reactor in R1 and R2

15 3.2 Hydraulic retention time (HRT) study After the sludge was stabilized to degrade the 30 mg/l of phenolic compounds, the HRT studies has been performed to evaluate the biodegradation performance of UASB rector at different HRTs has shown in Tables 1-4. The reactors were operated for days in each HRT. when the reactor was reached to steady state conditions. In the control reactor the COD reduction has been increased from 92 to 99% by increasing the HRT from 8 to 30h. Where as in the case of 4C-2-NP, the COD removal was decreased from 96.7% to 91% with decreasing the HRT from 30 to 8h and the compound removal efficiency also decreased from 94.6 % to 89% and also found that 24h HRT was the optimum HRT for the degradation of 4C-2-NP. In case of 2C-4-NP, the COD removal was decreased from 95 % to 81% with decreasing the HRT from 30 to 8h and the compound removal efficiency also decreased from 94.6 % to 85% and also found that 24h HRT was the optimum HRT for the degradation of 2C-4-NP.But in case of 2C-5-MP, the COD removal efficiency was decreased from 96 % to 65 % with decreasing the HRT from 30 to 8h and the compound removal efficiency also decreased from 94.6 % to 85% and also found that 24h HRT was the optimum HRT for the degradation of 2C-5-MP.The intial height). In the Control reactor VFA was varied from mg/l where as in the case of 4C-2-NP, the VFA was ranging from 99 to 456 mg/l and also in the case of 2C-4-NP, the VFA was ranging from 84 to 533 mg/l. But in the case of 2C-5-MP, the VFA concentration

16 was ranging from 98 to 698 mg/l. This indicates the toxicity of methyl phenols comparing with nitro phenols. The same trend has been followed in case of Methane percentage also. The ORP values were ranging from - 240mv to -285 mv which indicates the active metabolism in side the reactor. The PH was ranging of the values anaerobic operating conditions (<0.5) through out the experiment indicating the stability of the UASB reactor.

17 Table1: Performance of Reactor R1 (control) at different HRTs HRT OLR kg COD/m 3 /d COD Removal % Effluent ph Effluent VFA(mg/l) Biogas L/day Methane % ± ± ± ± ±

18 Table 2: The effect of HRT on the biodegradation of 4C-2-NP in R2 reactor HRT OLR kg COD/m 3 /d COD Removal % 4C-2-NP (mg/l). Influent Effluent Effluent ph Effluent VFA(mg/l) Biogas L/day Meth % ± ± ± ± ±

19 Table 3: Performance of Reactor R3 for the Treatment of 2C-4-NP at different HRTs HRT OLR kg COD/m 3 /d COD Removal % 2C-4-NP (mg/l) Influent Effluent Effluent ph Effluent VFA(mg/l) Biogas L/day Meth % ± ± ± ± ±

20 Table4: Performance of Reactor R4 for the Treatment of 2C-5-MP at different HRTs HRT OLR kg COD/m 3 /d COD Removal % 2C-5-MP (mg/l) Influent Effluent Effluent ph Effluent VFA(mg/l) Biogas L/day Meth % ± ± ± ± ±

21 3.3 Substrate: co-substrate ratio study In the present study an attempt has been made to evaluate the effect of substrate like glucose concentration on the performance of the reactor was carried. Tables 5,6,7 and 8 shows the performance of UASB reactor at different substrate: co-substrate ratios from 1:100 to 1:166.6 for the degradation of phenolic compounds. In the control reactor, when the glucose concentration was increased from 1000 mg/l to 5000mg/l, the COD removal efficiency has been decreased from 95 % to 91% and the biogas production has been increased to 3.7 l to 8.4 l/day. Where as in the case of 4C-2-NP fed reactor, when the glucose concentration was increased from 1000 mg/l to 5000mg/l, the COD removal efficiency has been decreased from 91 % to 90% and the biogas production has been increased to 2.9 l to 7.5 l/day. In case of 2C-4-NP fed reactor, when the glucose concentration was increased from 1000 mg/l to 5000mg/l, the COD removal efficiency has been decreased from 92 % to 89 % and the biogas production has been increased to 3.0 l to 6.9 l/day.

22 Table 5: Performance of Reactor R1 (Control) at different substrate: co-substrate ratio study: OLR COD Effluent Effluent Biogas Methane glucose(mg/l) kg Removal VFA(mg/l) % COD/m 3 /d % ph L/day 1020± ± ±

23 3995± ± Table 6: Performance of Reactor R2 for the Treatment of 4C-2-NP at different substrate: co- substrate ratio study: glucose(mg/l) OLR kg COD/m 3 /d COD Removal % 4C-2-NP(mg/l) Influent Effluent Effluent ph Effluent VFA(mg/l) Biogas L/day Me 1020± ± ± ± ±

24 Table7: Performance of Reactor R3 for the Treatment of 2C-4-NP at substrate: co-substrate ratio study: glucose(mg/l) OLR kg COD/m 3 /d COD Removal % 2C-4-NP(mg/l) Influent Effluent Effluent ph Effluent VFA(mg/l) Biogas L/day M 1020± ± ± ± ±

25 Table 8: Performance Of Reactor R4 For the Treatment of 2C-5-MP at substrate: co-substrate ratio study: glucose(m g/l) OLR kg COD/m 3 /d COD Remov al % 2C-5-MP(mg/l) Influe Efflue nt nt Efflu ent ph Effluent VFA(mg/l) Biog as L/da y Metha ne % 1020± ± ± ± ±

26 3.4 Characteristics of Granular sludge The Scanning electron microscope results showed that the surface of the granule was rough and uneven. The granule was a black colour with a spherical shape. On the surface of the granules large cavities were present. The bacteria will adhere to the other bacteria and that bacterial group will adhere to the other bacteria and make a group of bacteria called granulation. The bacteria which is present in the granule will degrade the organic matter present in the wastewater and converted in to carbon di oxide and methane. The biogas was produced from the granule. These results are similar to that of kursheed karim et al., 2004 when they are degrading the nitrophenols degradation by using UASB. Figure 11 shows the Scanning electron microscope of methanothrilix like bacteria are present inside the granules. These are generally present in acetate degrading biomass and easily degradable substrates like glucose, sucrose, fructose etc. The inorganic crystals are also present inside of the granules. Inorganic nutrients and bridging effect has been taken in side the granule of the reactor. The inorganic elements like iron and calcium could be observed on the layer of the anaerobic granule. These values are similar to that of Delia teresa sponza et al., 2006 for the degradation of 4- Chlrophenol by using molasses as a co-substrate.the contents of the phenolic compound degrading sludge shows that higher percentage of calcium and iron and minute cncentration of inorganic elements like

27 nickel, zinc, copper, molybdenum, potassium and sodium have been observed in the present study. These elements play a major role and used as a support materials for the formation of granules in the anaerobic granulation process. Before treatment the size of the granule was observed as 0.22mm and after the treatment the size of the granule was increased to 1.6mm. The sludge volume index in the all rectors are ranging from to ml/g, because the pellitization of the sludge was occurred then the decrease in the sludge volume index, the settlability of the sludge also increases. When the OLR was increased from 1kg COD/ m 3 /d to 5kg COD/ m 3 /d, the sludge bed height also increased. At 1kg COD/ m 3 /d the sludge bed height was varied from 14% to 18%. But at 5kg COD/ m 3 /d the sludge bed height was increased and varied from 32-33% in all the reactors. Inside the reactor 60% of the granulation has been occurred at the end of the operational condition. These values are similar to that of Ghangrekar et al., The ash content of the sludge was varied from 14-18% at 1kg COD/ m 3 /d and it was decreased to 11-13% at 1kg COD/ m 3 /d has been observed. The VSS/SS ratio of sludge increased marginally from 0.4 to 0.55 with increase in the organic loading. This shows that the ratio was less than as given in the literature for the good quality granular sludge.

28 Figure 5: SEM photograph of a granule showing filamentous bacteria and cavities

29 Figure 6: SEM photograph of of granules showing Methanothrix like bacteria

30 Figure 7: SEM photograph shows group of Methanobrevibacter like bacteria

31 Figure 8: SEM photograph shows inorganic crystals inside the granular biomass

32 3.5 Cost estimation: Cost estimation was done for a UASB reactor on the basis of waste water generation. The overall costs are represented by the sum of the capital costs, the operating and maintenance costs. Cost estimation is used for the evaluation of feasibility to the pilot plant mode so that further this information will help to industry in scale up of the reactors. In the large scale systems these costs all are depend on the type of pollutant and how much concentration was present in that wastewater, and also depend on the quantity of wastewater, flow rate of the wastewater and size of the designed system. Table 9 shows the overall operational cost including substrate, electricity and nutrients for the degradation of phenolic compounds. The total estimated operational cost was 2.6 US $ for degrading 60 m 3 /day wastewater contain phenolic compounds. But for reuse of wastewaters this cost is competitive by comparing with treated wastewater. These values are similar to that of daneil et al., 1999 for the treatment of wastewater and potential reuse applications.

33 Table 9: operational cost for the UASB reactor S.No Requirement Cost (US $/day) 1. Glucose Electricity Nutrients Total 2.6

34 Fig 9: HPLC analysis of influent 4C-2NP at 20 ppm

35 Fig 9: HPLC analysis of outlet 4C-2NP at 20 ppm

36 Fig 11: HPLC analysis of influent 2C-4NP at 20 ppm

37 Fig 12: HPLC analysis ofoutlet 4C-2NP at 20 ppm

38 5.1 Treatment of Bulk Drug Pharmaceutical Industrial Wastewaters By Using Up Flow Anaerobic Sludge Blanket Reactor Performance of the UASB reactor at different OLRs The reactor operated with higher organic loading rates after attaining a consistent stable carbon removal condition at OLR of 1 Kg COD/ m 3 /day to assess the optimum loading rate during process optimization. The COD was slowly increased to 2 Kg COD/m 3.d where the inlet of UASB reactor was modified with pharma effluent. Experimental investigations has been carried out up to 12 Kg COD/m 3.d for the evaluation of performance of the reactor. At each OLR, continuous operation of the reactor where the COD reduction and BOD reduction has been decreased to 80-85% after that slowly increasing to the other organic loading rate. The performance of the reactor in terms of COD and BOD reduction for the treatment of pharmaceutical wastewater was given in Figure During the startup of the COD reduction was 55% and the BOD reduction was 70%, after the 15 th day of the startup of the reactor the COD reduction was gradually increased to 70-75% and the BOD reduction was gradually increased to 90%. At each increment of the influent COD concentration, the COD reduction has been dropped slowly and recovered with in 5-6 days indicates the adaptation of microorganisms to the wastewater as a substrate. Figure shows the reactor performance at various organic loading rates. When the inlet concentration was increased from 1 to 10 Kg COD/m 3 /day, the gas

39 production rate also increases from 0.40ml/mg to 0.46 ml/mg and also indicates that when the COD concentration increased from 50 to 75%. These values are similar to that of vally et al., 2008 when they are treating with coke wastewater containg some aliphatic compounds. The optimization of organic loading rates for the treatment of pharma effluent in UASB reactor is shown in Figure This figure shows that for every organic loading rate maintained for days and when the reactor was reached to steady state conditions, the OLR was increased to higher concentrations that indicates microorganisms present in the reactor was slowly adapting and stabilized to 90-95% with in 20days. Optimization of OLR was the important step for the scale up studies and also in industrial application for the treatment of these type of effluents. These values are nearly similar to that of Chettiappan et al., 1996 for the biodegradation of penta chloro phenol by using anaerobic-aerobic sequential reactors. The biogas production was carrying from 0.89 l/day to 9.5l/day. When we had increased the OLR from 1Kg to 12 kg COD/m3/day, the biogas production was gradually increased to 890 ml/day to 10,000 ml/day. These results showed that gradual increase in the COD concentration was converted in to biogas. At an OLR of 1Kg, the biogas production was 890ml/day, at an OLR of 2 kg, the biogas production observed was 1750 ml/day, During the shock loads when the OLR was gradually increased to 2Kg to 5 Kg drastically, the biogas production was dropped from 1750ml/day to 250ml/day, this indicates

40 that sudden toxicity of microorganisms to the pharmaceutical wastewater and again we had decreased the OLR to 2 Kg, the biogas production was slowly recovered to 250ml to 650 ml with in three days and gradually increased to 1600ml/day, indicates that stabilization of the microorganisms has been happened with in 20 days. at an OLR of 3Kg, the biogas production observed was 2700ml/day, at an OLR of 4 Kg, the biogas production observed was 3800 ml/day, where as in the case of an OLR of 5, the biogas production seen was 4650ml/day on 80 th day because of the anaerobic granulation was observed. At an COD concentration of 6Kg, the gas production observed in reactor on 95 th day was 5850 ml/day, at a COD concentration of 7 Kg, the methane gas production was observed on 100 th day was 6500 ml/day, at an organic loading rate of 8 Kg, the methane gas production was observed on 120 th day was 7550 ml/day, at an COD concentration of 9Kg, the gas production seen was 8800 ml/day. After the 9Kg of COD the COD was suddenly increased to 13Kg COD, the methane gas production suddenly droped from 8800 ml/day to 500ml/day. This indicates the toxicity of pharmaceutical wastewater towards anaerobic sludge present in the reactor. At this COD concentration the COD and BOD reduction was also dropped suddenly and with in 5-6 days the gas production was slowly increased from 500 to 4500 ml/day and then slowly increased to 8000 ml/day with in 5-10 days. It indicates that when we had increased suddenly to higher loading rates, the enzyme activity of microorganisms

41 suddenly got toxic shock to the pharmaceutical wastewater. The sulfate concentration present in the bulk drug pharmaceutical wastewater contains 450 mg/l. The sulfate concentration was gradually decreased to 400 mg/l at 20 th day it indicates the sulfate utilization was started by the anaerobic bacteria which was present in the sludge. The sulfate concentration was then gradually decreased from 400 to 350 mg/l on the 45 th day in the anaerobic treatment of pharmaceutical wastewater. When the sulfate concentration was high in wastewater and that will utilize the microorganisms that will give toxic nature of the wastewater. Sulfates are degraded by the bacterium called Desulfobacterium which will degrade the sulfates and converted in to hydrogen sulfide.

42 Figure 1: Performance of the UASB reactor for the removal of COD and BOD during the period of operation.

43 Figure 2: Performance of UASB reactor at various organic loading rates.

44 Figure 3: Optimization of organic loading rate in UASB reactor.

45 Figure 4: Variation of VFA concentration and variation of SMA during the period of operation.

46 Figure 5: GC-MS analysis of pharmaceutical wastewater before treatment

47 Figure 6: GC-MS analysis of pharmaceutical wastewater after treatment

48 3.2. Performance of the reactor under shock loading In industrial scenario, frequently bioreactors would be under shock loads and therefore it is important that the reactor should be restored to normalcy withstanding the shock loads for better performance (Gangagni Rao et al. 2005). Therefore, organic shock load tests are carried out in the present studies to assess the reactor stability at two stable OLR. The data obtained is presented in Table 1. The reactor is stabilized at 1.0 COD/m 3 /day and the OLR is increased to 5 Kg COD/m 3 /day to observe the reactor performance for organic shock loading. It can be observed from the table that due to organic shock loading, the reactor performance significantly dropped with respect to carbon removal and specific methanogenic activity. Therefore, again the OLR is brought back to 1.0 Kg COD/m 3 /day where in the reactor performance is restored to normal stage. Organi Inlet OLR Outlet OLR No. of COD Gas Specific c (kg (kg days of reductio productio methanogen shock COD/m3/da COD/m3/da operatio n n per ic loads y) y) n (%) unit activity(ml- at each COD CH4/g-VSS OLR reduced d) (ml/mg)

49 Shock load at OLR Shock load at OLR Table 1: Performance of UASB at different organic shock loading

50 Figure 5: SEM micrograph showing methanosaetae like bacteria

51 Section-3 Treatment of Dye manufacturing Wastewater by Using up Flow Anaerobic Sludge Blanket Reactor 3.1. Start-up of reactor with domestic sewage for the treatment of dye manufacturing wastewater: Normally reactors are started by acclimatizing the native biomass with sewage [Nandy & Kaul 2001]. The characteristics of sewage before and after treatment are given in table2. Table 2: Characterization of domestic sewage before and after treatment during the start up of the anaerobic UASB reactor: S.NO parameter Before treatment After treatment (mg/l) 1 ph Electrical conductivity 190μ siemens 101μ siemens 3 Alkalinity Chemical oxygen demand (COD) Biochemical oxygen demand (BOD) 6 Sulphates Nitrates 15 8

52 8 phosphates 4.56 Nil 9 Total solids Total dissolved solids Volatile fatty acids Total suspended solids *All the values are expressed as mg/l except ph and EC

53 COD Concentration (mg/l) % COD Reduction 400 COD COncentration (mg/l) % COD Reduction Time (Days) Figure2: % of COD reduction during the treatment of UASB reactor with sewage.

54 BOD Concentration (mg/l) % COD Reduction 200 BOD cocentration (mg/l) % BOD reduction Time (Days) Figure 3: % of BOD reduction during the treatment of UASB reactor with sewage.

55 Biogas production (ml) Methane percentage 500 Biogas production (ml) Methane percentage(%) Time (Days) Figure 4: Biogas production and methane percentages during the treatment of UASB reactor with sewage.

56 3.2 The performance of the UASB reactor at different COD concentrations: After attaining a consistent stable carbon removal condition at COD concentration of 400 mg/l, the reactor is operated with higher organic loading rates to assess the optimum loading rate for process optimization. The COD was gradually increased to 800 mg/l at which point the feed to the CSABR reactor was progressively modified by introducing the pharmaceutical waste water. The performance of the reactor is evaluated up to 4000 mg/l. The results obtained from the study were presented in a graphical form and subsequently discussed (Table-2). Operations of batch reactor at different organic loading rates relating COD removal with respect to time are depicted in Fig.2. It can be visualized from the figure that a considerable COD reduction was observed at different organic loading rates. In case of 800 mg/l of COD concentration, COD reduction of 35% of total concentration was observed at the end of 24 hours and reduction increased to 60% at the end of 48 th hour. COD removal of 90% was observed at the end of 72h at this OLR. No further degradation was observed after attaining a maximum reduction of 90% at the end of 72 hours, till the 96 th hour. In case of 2000 mg/l of COD concentration, 50% reduction was observed after 48 hours which continued to 85% after 72h and remained stable up to 110h

57 indicating the maximum possible COD reduction at this OLR. While at 2800mg/l of COD concentration, where 30% COD reduction was observed after 50 hours and continued progressively to a maximum removal of 80% at the end of 120 hours and remained constant up to 8 days (170h). Finally at 4000 mg/l of COD concentration, 25% of COD reduction was achieved after 50h which increased subsequently to 46% after 96h and further reached steady state condition at the end of 140h with a maximum reduction of 48%. This indicates that methanogenic inhibition towards toxicity of dye manufacturing industrial effluents. From the above discussion, we can state that the COD reduction is dependent on the organic loading rate and the steady state conditions of the reactor. The optimal loading rate was understood as 2800 mg/l of COD concentration of COD where 80% reduction was observed. The reactor was further operated at this OLR for four consecutive batches and found the result to be concurrent with COD removal ranging between 65-70% confirming the 2800 mg/l of COD concentration as optimum loading rate. During the operation of the reactor, the ph and alkalinity of the effluent were analyzed at regular intervals. The ph was measured every day and maintained in the range of , which is optimum range for methanogenesis. The best operation of anaerobic reactors can be expected when the ph is maintained near neutrality [Rajeswari et al.2005]. ph values are represented in Fig. 3. Alkalinity is very essential parameter as it provides the required buffering capacity to

58 anaerobic system. Hence bicarbonate alkalinity was monitored everyday for all organic loading studied. Bicarbonate alkalinity ranged between mg/l through out the study, indicating the required buffering for the anaerobic consortia. 3.3 Variation of Oxidation Reduction Potential (ORP) in UASB reactor ORP is useful in the evaluation of magnitude, characteristic, and process change of an anaerobic system. In most complex biological systems, the main chemical and biological oxidation and reduction-taking place are not in equilibrium and the observed ORP cannot be interpreted thermodynamically. The observed ORP represents the net electron activity of all the redox reactions taking place and thus indicate the general oxidation and reduction status of the system [Charpentier et al.1998]. ORP can be used for diagnosis of problems in malfunction of treatment process. The ORP values varied between 35 to 49 at COD concentration of 800 mg/l; -40 to 54 at COD concentration of 2000 mg/l; -27 to 45 at COD concentration of 2800 mg/l; -35 to 61 at COD concentration of 4000 mg/l; 31 to 54 at 8.0 Kg/m 3.day OLR confirming the favorable conditions prevailing in the anaerobic reactor Variation of Volatile Fatty Acids (VFA) in the reactor Inhibition of methanogenic population by volatile acids is considered as the prime reason for digester failure [Arceivala et al.1998]. This is the main reason for which VFA s were analyzed for every organic loading

59 studied. Volatile fatty acids above 250 mg/l is considered to decrease the activity of the anaerobic process but studies indicate that even at concentration of 1200 mg/l of VFA the anaerobic process is not hampered [Das 1998]. Moreover the VFA: Alkalinity must be in the ratio of 0.1 in the efficient functioning of the anaerobic system [Arceivala et al.1998]. In the present study VFA was in range of mg/l which is in good agreement with the above statement Variation of Sulphates through operation period High sulfate concentration in wastewater is found to be inhibitory to the anaerobic process. The reduced products of sulfate reduction, particularly H2S are also inhibitory to methanogenesis [Hilten et al.1998]. Studies indicate that by dilution of the waste, at elevated levels of ph in the reactor, presence of metal ions particularly iron promote methanogenesis [Omil et al.1996]. In the present study slight sulfate reduction was observed through out the study.the initial sulphate concentration is 250mg/l present in the effluent, after treatment the sulphate concentration was reduced to 110mg/l Variation of Methane gas productions and CH4 percentages in UASB reactor Anaerobic treatment owes much to the renewable energy resources. The augment of gas collection through the displacement of water was made to

60 notice indication of gas production. The biogas produced was monitored daily for each organic loading rate and the gas production trend with COD utilization is presented in Fig.5. After a satisfactory startup, the reactor was operated until steady state performance was reached indicated by a constant gas production rate (±5%). Gas production of 700ml was measured at COD concentration of 800 mg/l while 1600ml of gas production was observed at COD concentration of 2000 mg/l. Further gas production volume increased to 2200ml at COD concentration of 2800 mg/l. At a COD concentration of 4000 mg/l, the gas production was further increased to 2600 ml from 2200ml. This indicated that as COD concentration increases the gas production also increased. This means The COD is concerted in to biogas. The Optimization of HRT for the treatment of dye manufacturing wastewater is given in Table 3. 3 days HRT is the optimum HRT for the degradation of dye manufacturing wastewater. The Optimization of ph for the treatment of dye manufacturing wastewater is given in Table 4. The ph 7 is the optimum HRT for the treatment of dye manufacturing wastewater 3.8. Colour removal during the treatment of dye manufacturing wastewater

61 The colour removal during the treatment of dye manufacturing wastewater is shown in figure Figure: Colour removal during the treatment of dye manufacturing wastewater

62 Table 2: Characterization of dye manufacturing wastewater before and after treatment: S.NO parameter Before treatment After treatment (mg/l) 1 ph Electrical conductivity 6550μ seimens 3500 μ seimens 3 Alkalinity Chemical oxygen demand (COD) Biochemical oxygen demand (BOD) 6 Sulphates Nitrates phosphates 0.4 Nil 9 Total solids Total dissolved solids Volatile fatty acids

63 Gas production % COD Reductuion 12 Total suspended solids *All the values are expressed as mg/l except ph and EC Gas production (ml/day) % of COD reduction COD Concentration (mg/l) Figure 5: The biogas production and percentage removal of COD during the treatment of dye manufacturing wastewater

64 ORP (mv) mg/l of COD 2000 mg/l of COD 2800 mg/l of COD 4000 mg/l of COD Time(hours) Figure 6: Variation of ORP during the treatment of dye manufacturing wastewater

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66 COD Concentration(mg/l) mg/l COD 2000 mg/l COD 2800 mg/l COD 4000 mg/l COD Time (Hours) Figure 7: COD concentration reduction during the treatment of pharmaceutical wastewater Table 2: COD and VFA removal efficiency at different COD concentrations during reactor performance.

67 Table3: Optimization of HRT for the treatment of dye manufacturing wastewater (Temp C, ph-7.0) S.No Time for complete COD(mg/L)%COD removal Volatile fatty acids as acetic Treatment (Hours) acid (mg/l) Inlet Outlet

68 HRT(d) Influent COD Total solids Biogas COD removal % Reduction% production (mg/l) Optimization of ph for the treatment of dye manufacturing wastewater ph Influent COD Biogas Colour Methane COD removal % production removal percentages (mg/l) References