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

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BOD (mg/L) 4000 3000 2000 1000 0 Raw Leachate Stripped Leachate Figure 4.42 Molecular Weight Cut-off of Leachate (a) BOD (mg/L) (b) BOD (%) While analyzing the BOD content of the fractions, it was found that 88% (BOD) of 91% (COD) of the > 50 k fraction was biodegradable. As this could be confirmed by the 3% remaining > 50 k COD content in the bacterial effluent after membrane bioreactor treatment. Looking at the BOD content in the effluent, it was found that in the yeast as well as the bacterial effluent < 5 k molecular weight components contributed to the maximum BOD when compared to the other fractions. The COD content also showed a similar trend. 114 Yeast Effleunt Bacterial Effluent MW>50k MW 10k-50k MW 5k-10k MW50k MW 10k-50k MW 5k-10k MW
Though, the obtained COD removal efficiency of both systems was slightly different, the majority of organic concentrations in both effluents were in the lower molecular weight range indicating that yeast and bacteria were effective in degrading high molecular weight organics. The high molecular weight organics may be highly refractory organics (Hosomi, et al., 1989). However, the effluent from both systems still consists of the medium molecular weight organics such as fulvic acid which are unaffected by biological treatment. It could be further treated with post treatment such as ozonation, increasing the biodegradable organics or even elevating the water quality of the final effluent. 4.5.3 Sludge Properties In the membrane coupled biological treatment systems, complete separation of microorganisms is possible; thus, high microbial concentration as well as excellent effluent quality (Kim, et al., 1998) can be achieved. The membrane biofouling could be largely affected by physico-chemical characteristics and the physiology of the activated sludge as well as the membrane materials (Sato and Ishii, 1991; Pouet and Grasmick, 1995; Chang, et al., 1996) Therefore, the sludge properties of the membrane bioreactors are important in terms of membrane fouling and sludge dewaterability. Dewaterability is usually measured in terms of Capillary Suction Time (CST) for evaluating the performance of sludge dewatering. Sludge Volume Index (SVI) is another indicator used to measure the settleability of the sludge. The bacterial sludge showed a better dewatering quality compared to that of the yeast system as shown in Table 4.15. As suspended solids also affect the sludge properties, the MLSS was also measured. Higher viscosity and dewaterability could be attributed to the difference between MLSS of mixed bacteria sludge and mixed yeast sludge. But, the difference in the MLSS was not found to be large. Table 4.15 Sludge Properties in the YMBR and BMBR Systems Sample Reactor DSVI (ml/gSS) Viscosity (cP) CST (s/g SS) SS (mg/L) 1 YMBR BMBR not settle not settle 6.24 13.00 - - - - 2 YMBR BMBR not settle 79 6.30 9.78 128 12 13,267 14,133 3 YMBR BMBR not settle 60 - - 126 10 13,367 13,233 Though the bacterial sludge showed a better dewaterability, the viscosity of the bacterial system was found to be more than that of the yeast system. The content of microfloc components, such as EPS might have an influence on the permeability (Kim, et al., 1998). This could be one of the reasons for a frequent membrane fouling in the bacterial system compared to that of the yeast system. Along with the MLSS, MLVSS of the sludge was also measured as given in Table 4.16. When MLVSS/MLSS was measured, it was found that the bacterial sludge had a lower degradability (0.6) compared to that of the yeast sludge (0.7). However, the difference between the degradability of the bacterial sludge and yeast sludge was not much. 115
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APPLICATION OF MEMBRANE BIOREACTOR
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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
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Activated Carbon Adsorption Granula
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Colloidal material as well as metal
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iologically, physical-chemical proc
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Ammonia Stripping Air stripping of
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These systems are land intensive wh
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the biological treatment can be rep
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Table 2.16 Typical Leachate Composi
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influent reached 200 mg/L. For the
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Table 2.18 Advantages and Disadvant
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through the effluent. Different ope
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Mixed Liquor Suspended Solids and D
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2.12 Yeasts 2.12.1 Introduction The
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Nishihara ESRC Ltd. (2001) studied
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nitrification-denitrification proce
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Table 3.1 Composition of Simulated
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3.4.1 Ammonia Toxicity The experime
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Figure 3.4 Experiments Conducted to
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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 and 92: Table 4.4 Effect of Free Ammonia Co
Page 93 and 94: Table 4.5 Substrate Utilization by
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: COD (mg/L) 8000 6000 4000 2000 COD
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
Page 143 and 144: Grady, C.P.L., Daigger, G.T., and L
Page 145 and 146: Keenan, J.D., Steiner, R.L., and Fu
Page 147 and 148: Martin, G.M.A., Auzmenti, A.I., and
Page 149 and 150: Pohland, F.G., and Harper, S.R., 19
Page 151 and 152: Shin, H.S., An, H., Kang, S.T., Cho
Page 153 and 154: Visvanathan, C., Ben Aim, R., and P
Page 155 and 156: Appendix A Pictures of Experiments
Page 157 and 158: Raw Leachate YMBR Effluent BMBR Eff
Page 159 and 160: Appendix B Leachate Characteristics
Page 161 and 162: Table B-2 Acclimation of Mixed Yeas
Page 163 and 164: Appendix C Experimental Data of Bio
Page 165 and 166: y: Where: OUR at line g: This is th
Page 167 and 168: Table C-3 Experimental Results for
Page 169 and 170: Appendix D Membrane Resistance Stud
Page 171 and 172: Table D-3 Experimental Data for Det
Page 173 and 174: Table D-4 Experimental Data for Det
Page 175 and 176: Pressure (kPa) Pressure (kPa) 25 20
Page 177 and 178: 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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