Thesis - faculty.ait.ac.th - Asian Institute of Technology

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NH3 + H + NH4 + At low pH, when H + is high, the equilibrium shifts towards the right direction. This results in low ammonia concentration. The low percentage inhibition in the yeast system could be attributed to this, as the operation pH of the yeast system is around 3.5 to 3.8 compared to 6.8 to 7.0 in the bacterial sludge. Though, the ammonia concentration did not affect the yeast sludge much, it was found to inhibit the microbial growth in the bacterial system. As the ammonium is present in high concentration in the leachate, leaching becomes necessary prior to further biological treatment. Thus, ammonia stripping was done to ensure better efficiency of the biological system and prevent the inhibition of the toxic compounds to the organisms. (2) Lead Toxicity Many researches have shown the presence of toxic compounds in many landfill leachate (Brown and Donnelly, 1988; Baun, et al., 1999). Other studies have shown that leachate from a municipal solid waste landfill can be more toxic than the leachate from the hazardous waste landfill (Brown and Donnelly, 1988; Schrab, et al., 1993; Clement, et al., 1996). Even though large scale disposal of hazardous toxic metals is no longer practiced, but small generators such as small businesses and households do continue to dispose hazardous chemicals in the municipal landfills (Brown and Donnelly, 1988). One of such compounds is the lead, which is present in the landfill leachate. The source of lead is probably from plumbing fixtures in the individual homes and other lead-containing products (such as leaded solder, battery, glass, PVC, and small lead items) which are disposed of as waste. Though, lead is found at a concentration lower than 1 mg/L (Chian and DeWalle, 1976; Ehrig, 1983; Keenan, et al., 1984; Robinson and Maris, 1985; Robinson, 1992), an increased concentration of the lead can pose failure of the biological systems. To find out the effect of the increasing lead concentration on the activated sludge, toxicity studies was done with it using lead nitrate as a lead source. The lead nitrate in the bacterial system was varied from 20-100 mg/L compared to 2-25 mg/L in the yeast system. The lead nitrate used in the yeast system was lower than that of the bacterial system due to the reason that at lower pH, lead would easily dissociate as a free ion (Cui, et al., 2000). The lead toxicity was done as described in section 3.4.2. The biokinetic parameters for the lead toxicity studies in bacteria and yeast leachate is given in Table C-5 and C-6 of Appendices C. The substrate concentration in the study was similar to that of the ammonia toxicity study. The substrate utilization by the yeast and bacterial sludge is presented in Table 4.5. It is found that the substrate utilization of the bacterial system is higher than that of yeast sludge. As the soluble lead concentration increased from 0 to 10.98 mg/L, the oxygen utilization rate decreased from 0.519 mg O2/mg VSS.h to 0.075 mg O2/mg VSS.h. The percentage inhibition at high concentration was found to be 85%. The inhibition effects of the lead on the bacterial and yeast system is expressed in Figure 4.10 and 4.11, respectively. 78
Table 4.5 Substrate Utilization by the Yeast and Bacterial Sludge Bacteria Yeast Soluble Pb in Oxygen Utilization Soluble Pb in Oxygen Utilization Sample (mg/L) (mg O2/mg VSS.h) Sample (mg/L) (mg O2/mg VSS.h) 0.00 0.519 0.00 0.071 2.38 0.233 1.15 0.042 4.11 0.233 1.41 0.042 5.23 0.158 1.98 0.032 10.98 0.075 2.10 0.017 % Inhibition . 100 80 60 40 20 0 0 2 4 6 8 10 12 Concentration of Soluble Lead (mg/L) Figure 4.10 Inhibitory Effect of Lead in Bacterial Sludge The soluble lead concentration in the yeast culture was from 0 to 2.10 mg/L concentration. The oxygen utilization rate of the yeast sludge decreased from 0.071 to 0.017 mg O2/mg VSS.h. The inhibition of the yeast system was 76% at a soluble lead concentration of 2.10 mg/L. The percentage of inhibition of yeast sludge was comparable to that of the bacterial sludge. The soluble lead concentration of 2.38 mg/L in the bacterial system showed 55% inhibition. In the yeast system, 50% inhibition occurred at a soluble lead concentration of 1.50 mg/L. The toxicity effect is close to that reported by Cui, et al. (2000), where it is said that toxicity effect on yeast occurs at concentration of 1 mg/L. 79
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APPLICATION OF MEMBRANE BIOREACTOR
Page 3 and 4:
Abstract Landfill leachate is a com
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Table of Contents Chapter Title Pag
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4.5.6 Cost Analysis for Operation 1
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4.4 Effect of Free Ammonia Concentr
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4.16 COD Concentration in the Influ
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MWCO Molecular Weight Cut-off MWW M
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1.1 Background Chapter 1 Introducti
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generally unsuccessful in removal o
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2.1 Introduction Chapter 2 Literatu
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In the municipal solid waste landfi
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COD/TOC, VS/FS and VFA/TOC ratios o
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Table 2.3 presents the general leac
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Ground water 2.7.1 Seasonal Variati
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Table 2.5 Variation of COD, BOD & B
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entails the re-circulation of leach
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Table 2.8 Summary of Biokinetic Coe
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that extensive loss of nitrogen (up
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ammonia could only be achieved when
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Table 2.10 Treatment Efficiencies o
Page 41 and 42: Activated Carbon Adsorption Granula
Page 43 and 44: Colloidal material as well as metal
Page 45 and 46: iologically, physical-chemical proc
Page 47 and 48: Ammonia Stripping Air stripping of
Page 49 and 50: These systems are land intensive wh
Page 51 and 52: the biological treatment can be rep
Page 53 and 54: Table 2.16 Typical Leachate Composi
Page 55 and 56: influent reached 200 mg/L. For the
Page 57 and 58: Table 2.18 Advantages and Disadvant
Page 59 and 60: through the effluent. Different ope
Page 61 and 62: Mixed Liquor Suspended Solids and D
Page 63 and 64: 2.12 Yeasts 2.12.1 Introduction The
Page 65 and 66: Nishihara ESRC Ltd. (2001) studied
Page 67 and 68: nitrification-denitrification proce
Page 69 and 70: Table 3.1 Composition of Simulated
Page 71 and 72: 3.4.1 Ammonia Toxicity The experime
Page 73 and 74: Figure 3.4 Experiments Conducted to
Page 75 and 76: Leachate Option Ammonia Stripping R
Page 77 and 78: MW larger than 50 kDa, (2) MW betwe
Page 79 and 80: Figure 3.7 Flowchart Showing Ammoni
Page 81 and 82: Chapter 4 Results and Discussion 4.
Page 83 and 84: COD Removal Effeciency (%) COD Remo
Page 85 and 86: MLSS (mg/L) 14000 12000 10000 8000
Page 87 and 88: Specific Growth Rate ( d -1 ) 0.50
Page 89 and 90: change in the predominant species w
Page 91: Table 4.4 Effect of Free Ammonia Co
Page 95 and 96: 4.3.1 Initial Membrane Resistance P
Page 97 and 98: when compared with the present stud
Page 99 and 100: COD Removal Efficiency (%) 90 80 70
Page 101 and 102: (2) TKN Removal Efficiency Prior to
Page 103 and 104: As there was no significant improve
Page 105 and 106: The probable reason for frequent fo
Page 107 and 108: Ammonia Concentration (mg/L) Ammoni
Page 109 and 110: concentration after treatment. Othe
Page 111 and 112: After the chemical cleaning of the
Page 113 and 114: emoval of 38%. A higher removal in
Page 115 and 116: Influent BOD (mg/L) Influent BOD (m
Page 117 and 118: (3) TKN Removal Efficiency The TKN
Page 119 and 120: Figure 4.34 gives the overall TKN r
Page 121 and 122: fraction and slowly biodegradable C
Page 123 and 124: BOD (mg/L) BOD (mg/L) 6000 5000 400
Page 125 and 126: Figure 4.39 Molecular Weight Cut-of
Page 127 and 128: COD (mg/L) 8000 6000 4000 2000 COD
Page 129 and 130: Though, the obtained COD removal ef
Page 131 and 132: cake used on the top of the membran
Page 133 and 134: Chapter 5 Conclusions and Recommend
Page 135 and 136: 0.02, respectively. This can be con
Page 137 and 138: References Abeling, U., and Seyfrie
Page 139 and 140: Brown, M.J., and Lester, J.N., 1980
Page 141 and 142: Diamadopoulos, E., 1994. Characteri
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Grady, C.P.L., Daigger, G.T., and L
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Keenan, J.D., Steiner, R.L., and Fu
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Martin, G.M.A., Auzmenti, A.I., and
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Pohland, F.G., and Harper, S.R., 19
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Shin, H.S., An, H., Kang, S.T., Cho
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Visvanathan, C., Ben Aim, R., and P
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Appendix A Pictures of Experiments
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Raw Leachate YMBR Effluent BMBR Eff
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Appendix B Leachate Characteristics
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Table B-2 Acclimation of Mixed Yeas
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Appendix C Experimental Data of Bio
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y: Where: OUR at line g: This is th
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Table C-3 Experimental Results for
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Appendix D Membrane Resistance Stud
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Table D-3 Experimental Data for Det
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Table D-4 Experimental Data for Det
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Pressure (kPa) Pressure (kPa) 25 20
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Appendix E MBR without Ammonia Stri
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Day HRT (h) pH COD (mg/L) Feed Reac
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Day HRT (h) pH COD (mg/L) Feed Reac
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Table E-3 Variation in TMP with Tim
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Appendix F Ammonia Stripping Studie
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Table F-5 Pilot Scale Study on Ammo
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Table G-1 Feed, Reactor and Effluen
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Table G-3 Feed, Reactor and Effluen
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Appendix H Other Studies 179
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Table H-2 Membrane Resistance of th
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Table H-6 Chemical Cost for the Yea
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