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

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Table 4.13 Determination of Membrane Resistance of Membrane Module after Clogging in BMBR system (A = 0.42 m 2 ; Pore Size = 0.1 µm) Membrane Resistance (m -1 Item ) 1 st Cleaning 2 nd Cleaning New membrane 7.07 x 10 11 7.07 x 10 11 After long run (BMBR) 9.19 x 10 13 1.41 x 10 14 After cleaning with tap water 1.97 x 10 13 2.43 x 10 13 After chemical cleaning 8.71 x 10 11 9.79 x 10 11 Total resistance (Rt) 9.19 x 10 13 1.41 x 10 14 Initial membrane resistance for next run (Rm) 8.71 x 10 11 9.79 x 10 11 Fouling resistance (Rn) 1.88 x 10 13 2.33 x 10 13 Cake layer resistance (Rc) 7.22 x 10 13 1.17 x 10 14 The total membrane resistance is a sum of cake layer resistance, intrinsic resistance and irreversible resistance due to fouling. The variation in transmembrane pressure with time in the MBR systems used for ammonia stripped leachate treatment is given in Figure 4.23. The membrane resistance after the long run was found to be 9.19 x 10 13 m -1 before the first cleaning. Which further increased to 1.41 x 10 14 m -1 before the second cleaning was done. The cake layer contributed to 79% of the total resistance during the first cleaning which further increased to 83% during the second cleaning. From the greatest contribution of cake resistance to the total resistance, one could conclude that the formation of cake layer played a major role in flux decline during filtration (Kim, et al., 1998). This could be due to some loss due to the irreversible resistance in the membrane. Trans-membrane Pressure (kPa) 70 60 50 40 30 20 10 0 BMBR YMBR HRT 0 50 100 150 Time (day) 200 250 300 Figure 4.23 Trans-membrane Pressure Variation in MBR Process for Ammonia Stripped Leachate Treatment 96 30 25 20 15 10 5 0 HRT (h)
After the chemical cleaning of the membrane during both the times, 99% of the initial membrane resistance could be obtained. The fouling resistance in the membrane bioreactor was 20% and 17% during the first and second cleaning, respectively of that of the total resistance. This indicated that the cake layer resistance was much higher than the fouling resistance in the membranes. The reduction in flux due to membrane biofouling is largely affected by physico-chemical characteristics and physiology of activated sludge as well as membrane materials (Kim, et al., 1998). The factors affecting the membrane fouling will be discussed in later part of this chapter. 4.4.3 Performance of Ammonia Stripping Coupled Membrane Bioreactor Process As the performance in terms of COD removal efficiency without ammonia stripping was not significant with 16 and 24 h HRT, the performance of MBR was evaluated in terms of both COD and BOD at HRT of 16 h followed by 24 h. Stable biomass retention in the MBR is effective in BOD removal. The MBR system though effective in BOD removal, is not easy to remove nitrogen (Ahn, et al., 2002). The optimum conditions derived from ammonia stripping studies as described in section 4.4.1 were used for ammonia removal. Ammonia removal was used for nitrogen removal instead of nitrification-denitrification process because old leachate does not have sufficient degradable organics to supply the bacteria with carbon needed for growth. The ammonia stripping was done once every three days to feed the membrane bioreactors. The performance could be evaluated as described below. (1) COD Removal Efficiency The COD of the influent leachate ranged from 7,600 to 8,200 mg/L with 16 and 24 h HRT. After the ammonia stripping, the leachate was fed into the feed tanks to feed membrane bioreactors. In both the operational conditions, with 16 and 24 h HRT, the average MLSS concentration ranged from 11,000 to 12,000 mg/L. The MLSS concentration was similar to the membrane bioreactors without ammonia stripping. The variation in the MLSS concentration and the influent COD influent with 16 and 24 h HRT is given in Figure 4.24 and 4.25, respectively. The advantages of biomass retention in membrane bioreactor are that, even the slow growing organisms, normally washed off in conventional process are retained in membrane bioreactor (Ben Aim and Semmens, 2002). The entire range of data is given in Table G-1 to G-4 of Appendix G. The fluctuations in the membrane bioreactor treatment in terms of COD removal with ammonia stripping were found to be lower than that without ammonia stripping. Both YMBR and BMBR reactor without ammonia stripping, did not show improvement in COD removal when the HRT was increased, while in both the systems there was slight improvement in COD removal when the HRT was increased. The nitrogen removal in the membrane bioreactor was satisfactory. The probable reason for nitrogen removal would have been denitrification rather than nitrification as there was not any sufficient increase in oxidized nitrogen compounds (Muller, et al., 1995). The COD removal in the YMBR and BMBR with the ammonia stripping was the same. Both the membrane reactors showed a COD removal of 72% at 16 h HRT and 76% at 24 h HRT. When Ahn, et al. (2002) treated leachate with 1,017 mg/L COD, they found that the MBR system could achieve a COD 97
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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
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 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: concentration after treatment. Othe
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
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
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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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