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

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The reactors were continuously aerated with the help of stone diffusers placed at the bottom of the reactors. The polyethylene hollow fibre membrane was kept in the upper end of the reactors. Peristaltic pumps were used to withdraw permeate from these membrane modules. The reactors were also equipped with the pH meter to monitor pH continuously. The pH of the yeast and bacterial reactor was maintained within the range of 3.5 to 3.8 and 6.8 to 7, respectively with the help of an external dosing pump. The DO in the reactors was maintained around 2-4 mg/L. Both the bioreactors were operated with periodic air backwashing. The filtration cycle of the reactor consists of 25 minutes of filtration, 3 minutes of air backwashing at a pressure of 300 kPa, and 1 minute of air release. The operation of filtration, backwash and release air was alternatively controlled with an intermittent controller and solenoid valves. The trans-membrane pressure (TMP) was measured using a mercury manometer. Sampling from the reactors was done from the sampling port. The sludge from the reactor could be withdrawn from a sampling port present in the bottom of the reactor. The treated leachate was collected in a container kept at the side of the reactor. The treated effluent corresponds to permeate from the membrane bioreactor. 3.6.3 Parametric Studies The experiments were done by varying the volumetric loading. The different organic loading rates (OLR) used in this experiment are summarized in Table 3.6. Each volumetric loading was maintained at least for 25 days. Furthermore, the excess sludge was periodically withdrawn to maintain a mean biomass concentration of 10,000 to 12,000 mg/L of MLSS. The pH in the YMBR system and BMBR system was maintained around 3.5 to 3.8 and 6.8 to 7.0, respectively. The varied mean hydraulic retention time in which the experiment was conducted are 12, 16, 20 and 24 hours. The hydraulic loading varied from 6.75 to 17.88 kg COD/m 3 .d . Table 3.6 Experimental Operating Conditions of YMBR and BMBR Systems Stage Time (days) 1 1-25 2 26-60 3 61-149 4 150-181 3.6.4 Molecular Weight Distribution Mean HRT (h) 24 20 16 12 62 OLR (kg COD/m 3 .d) 6.75-8.33 7.60-11.14 9.54-14.40 13.92-17.88 To investigate the composition of organic content in the leachate on the basis of their molecular weight, ultrafiltration membrane (UF) was used. Ultrafiltration was performed in a 300 ml cell, using flat circular membrane of 76 cm diameter with molecular weight cut-off (MWCO) of 5,000, 10,000, and 50,000 Daltons (Da). Nitrogen gas was used to apply pressure in the UF cell at about 2 bars (Gourdon, et al., 1989; Huang, at el., 2000). The three types of UF with molecular weight cutoff ranges are presented in Table 3.7. The fractionated organics in the treated leachate were also measured to find out the organic removal efficiency of the membrane bioreactor in terms of their molecular weight. The organics were fractionated into four groups based on their molecular weight (MW): (1)
MW larger than 50 kDa, (2) MW between 10 kDa and 50 kDa, (3) MW between 5 kDa and 10 kDa, and (4) MW less than 5 kDa. The procedure for molecular weight distribution study is described in Figure 3.6.The procedure for molecular weight distribution is as follows: 1. 100 mL of sample was filtered in a 0.45 µm membrane before fractionating it with UF at 50 kDa MWCO at a pressure of 2 bars for 30 minutes. 2. The permeate of the UF membrane used for 50 kDa MW was collected and further fractionated with serial processing method using the corresponding UF at 10 kDa, and 5 kDa MW, using the same mode of operation. 3. The volume of retentate of each fraction and permeate obtained after 5 kDa MW UF were measured and analyzed for COD concentration. Leachate 50 kDa MW Permeate 10 kDa MW Permeate 5 kDa MW Permeate Figure 3.6 Methodology for Performing Molecular Weight Cut-off Distribution 63 Retentate Retentate Retentate
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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
Page 7 and 8:
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
Page 25 and 26: Table 2.3 presents the general leac
Page 27 and 28: Ground water 2.7.1 Seasonal Variati
Page 29 and 30: Table 2.5 Variation of COD, BOD & B
Page 31 and 32: entails the re-circulation of leach
Page 33 and 34: Table 2.8 Summary of Biokinetic Coe
Page 35 and 36: that extensive loss of nitrogen (up
Page 37 and 38: ammonia could only be achieved when
Page 39 and 40: 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: Leachate Option Ammonia Stripping R
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
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COD (mg/L) 8000 6000 4000 2000 COD
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Though, the obtained COD removal ef
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cake used on the top of the membran
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Chapter 5 Conclusions and Recommend
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0.02, respectively. This can be con
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References Abeling, U., and Seyfrie
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Brown, M.J., and Lester, J.N., 1980
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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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Thesis - faculty.ait.ac.th - Asian Institute of Technology

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