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

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Trans-membrane Pressure (kPa) 70 60 50 40 30 20 10 0 YMBR BMBR HRT 0 20 40 60 80 100 120 140 160 180 Time (day) Figure 4.20 Cleaning of membranes in the YMBR and BMBR system in relation to TMP Table 4.10 Membrane Cleaning Frequency in the MBR Systems Membrane Cleaning Days after Membrane Operation BMBR YMBR 1 63 80 2 85 101 3 126 154 4 143 - 5 167 - Table 4.11 Membrane Resistance in the MBR Systems Membrane Resistance (m -1 Cleaning Frequency ) after Cleaning BMBR YMBR Initial 6.29×10 11 6.66×10 11 1 1.79×10 12 5.64×10 11 2 1.02×10 12 3.31×10 12 3 1.13×10 12 1.31×10 12 4 2.81×10 12 - 90 26 22 18 14 10 HRT (h)
The probable reason for frequent fouling in bacterial system than yeast system could be EPS formation. The EPS formation in reactor was greater in bacterial system than in the yeast system. The mechanism of biofilm development in the YMBR is different from that of the BMBR. In the YMBR, the yeasts attach itself physically to the membrane surface during filtration instead of getting trapped in a matrix as the bacterial cell. The yeast cells usually attach together by means of physical interwinding of mycelia or pseudomycelia (Nishihara ESRC Ltd., 2001). Another probable reason for frequent fouling in the bacterial based membrane bioreactor could be the size and nature of bacterial cells in comparison with the yeast cells. The bacterial cells have a size of 0.5 to 1.0 µm diameter for the spherical shaped, and 0.5 to 1.0 µm wide and 1.5 to 3.0 µm long for the cylindrical (rods) shaped bacteria whereas the size of yeast is around 5 to 30 µm length and 1 to 5µm width. The large yeast cells are said to form a dynamic membrane on the top of the original membrane that is capable of entrapping some of the protein aggregates. This may enhance the recovery of the viscous aggregates and thus slowing down the fouling layer on the surface of the primary membrane. Thus, the yeast interactions slow down the pore blocking by capturing a significant fraction of protein aggregates (Guell, et al., 1999). In addition to this low operating pH, poor adhesion capacity and low viscosity could be other reasons for low fouling frequency in the yeast based MBR systems (Dan, 2002). Thus, yeast sludge can reduce membrane fouling rate more significantly than the bacterial sludge. Therefore, it could be suggested that the use of yeast system in the membrane bioreactor could be beneficial as it has the potential to reduce the operating and maintenance costs of the treatment system. 4.4 Application of Yeast and Bacteria Based Membrane Bioreactors in Ammonia Stripped Leachate Treatment Leachate with high load of refractory compounds, low value of BOD/COD ratio, heavy metals and high concentration of nitrogen compounds, especially ammoniacal exhibit difficulty in treatment (Dichtl, et al., 1997). Biological treatment becomes difficult when the regarded leachate is inhibitive, toxic and older-less biodegradable (Geenens, et al., 1999). Due to the presence of high ammonium content in the leachate, it could be suggested that removal of ammonium is required prior to biological membrane treatment. 4.4.1 Ammonia Stripping Studies The toxicity of ammonia-bearing waste to bacteria, algae, zooplankton and fish is a universal phenomenon. Ammonia has been shown to be toxic in oxidation ponds where high free ammonia and pH inhibit photosynthesis (Abeliovich and Azov, 1976). The activated sludge process has also been shown to fail due to the ammonia toxicity and phosphorous limitation (Keenan, et al., 1984). In addition, Cheung, et al. (1993) through algal toxicity suggested that ammonia concentration as ammoniacal nitrogen is a major factor governing the toxicity of landfill leachate. Along with this, it was difficult to overcome the ammonia toxicity and to treat the leachate containing a low COD/N ratio with biological process (Keenan, et al., 1984; Robinson and Maris, 1985; Cheung, et al., 1997). Therefore, there is a need to reduce the concentration of ammonia in the leachate below inhibitory level for the success of biological systems in proper leachate treatment. As ammonia stripping is simple and less expensive than other physico-chemical methods 91
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APPLICATION OF MEMBRANE BIOREACTOR
Page 3 and 4:
Abstract Landfill leachate is a com
Page 5 and 6:
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
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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
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 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: As there was no significant improve
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
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
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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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