Experimental Study of Biodegradation of Ethanol and Toluene Vapors

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Equation (5-65) indicates that the biomass concentration always depends on the substrate feed concentration (y in ), and the higher the feed concentration the higher will be the biomass concentration. If ethanol gas inlet concentration were kept constant with all dilution rates, biomass levels would be too high at low dilution rates and they will be too low for the higher dilution rates. Therefore, we can increase ethanol gas inlet concentrations as the dilution rate increases. y in e , = f ( D * V / Q) (5-66) The prediction of continuous removal of ethanol was based on varying gas inlet concentrations (Equation (5-66)), i.e. y e , in proportionally increases with increasing dilution rates. Using the values of parameters obtained for ethanol bioremediation listed in Table 5.1, and operating under steady state continuous conditions −1 ( = 0.010C − mol / C − mol. h ) using the typical levels employed in this study m , c e 24L / h, V 1.5 ) ( Q = R L , the ethanol removal in a CSTR at steady state can be predicted = Figure 5-14a shows the results of biomass (X), substrate (ethanol, C e ), ammonia by Equations (5-63) and (5-65) as a function of dilution rate and inlet ethanol concentration. (C n ), and dissolved oxygen (DO) concentrations for different values of ethanol addition rates. In Figure 5-14a, the term m e,c is significant at low dilution rates, and the biomass concentration (X) becomes smaller than if maintenance is neglected; i.e. at low dilution rates, the substrate is consumed for maintenance of the biomass. At very high dilution rates (close to μ m ), the cells are washed out (X=0), and the ethanol concentration (C e ) 132
corresponds with the value associated with 100% of the ethanol from gas stream being dissolved in the liquid phase, i.e. maximum addition of ethanol through the gas phase. The ammonia concentration in the liquid phase is calculated by: C C − 0.2C (132 / 2) (g/L) (5-67) N = N 0 x ⋅ This is derived from D(C N0 -C N ) = 0.2 μ C x at steady state. At steady state, oxygen consumption equals oxygen mass transfer rates, then the DO level is determined by coupling Equations (5-59a) and (5-59b): * DO = C = C − Q k a (5-68) o O O / 2 2 2 L The ammonia concentration remains higher than 1.7 g/L for all dilution rates up to 0.32 h -1 due to the continual addition of the fresh medium at a level (C n0 = 2.0 g/L) which is sufficient for the cells’ growth. The DO values are higher than 4 mg/L for steady state operations ( μ < 0.32h −1 ). When the dilution rate is higher than 0.32 h -1 , the cells are washed out and the DO is the same as the maximum dissolved oxygen in the medium solution (7.0 mg/L). The results in Figure 5-14a predict that both the ammonia and oxygen are sufficient to support the steady state operations at all dilution rates up to 0.32 h -1 . When the dilution rate is greater than 0.32 h -1 , the cells are washed out so there is no demand for oxygen and ammonia. We can conclude that the dilution rate should not be set too low or too high for steady state operation in the continuous removal of ethanol from polluted air. Figure 5-14b shows the predicted results of biomass (X) and substrate (ethanol, C e ) concentrations, and dissolved oxygen level (DO) at higher ethanol addition rates, i.e. y e in = , 0.14D( V / Q) . The DO level decreases as dilution rates increase. When the dilution rate is higher than 0.1 h -1 , DO declines to a level that is below the 133
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BIOREMEDIATION OF VOLATILE ORGANIC
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ABSTRACT The mass transfer of ethan
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effect on the growth of P. putida.
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ACKNOWLEDGMENT Of the countless peo
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TABLE OF CONTENTS PERMISSION TO USE
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4.3 Batch Growth on Ethanol and Ben
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LIST OF FIGURES Figure 3-1. Schemat
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Figure 5.3 (b) Simulation of ethano
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Figure 5-16. Continuous removal of
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NOMENCLATURE a - Interfacial area,
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CHAPTER ONE - INTRODUCTION 1.1 Air
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esults (van Groenestijn and Hesseli
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experimental results are presented
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Table 2.2 VOC Emissions in the U.S.
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(paint shop effluents, for instance
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combustion provides 70 to 90% air p
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used to degrade ethanol vapours and
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g m -3 . This would suggest that th
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treatment, This excessive biomass f
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The simultaneous degradation of tol
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emoves only water-soluble gases. Wa
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2.2.6 Pseudomonas It is well known
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2.3.2 Growth Models with Inhibition
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where µ is the total specific grow
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2.4.1 Batch Reactor In a batch reac
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discharged from the other end. The
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element solution consisted of (gram
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growth on ethanol, 20-48 hours for
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Gas phase samples of toluene were c
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Inlet sampler Exit sampler To fume
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Once the oxygen meter indicated a s
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centrifuged and the supernatant was
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where k L a is the volumetric mass
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Figure 4-2a shows ethanol liquid co
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coefficient (k L a) in the well-mix
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calculated by dividing the gas volu
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Average bubble diameter, mm 8 7 6 5
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Bioflow III bioreactor. Equation (4
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3.5 y=Ln(S0/S) 3 2.5 2 1.5 1 y = 12
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Ethanol and biomass concentration,
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4.3.2 Batch Growth on Benzyl Alcoho
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Biomass and benzyl alcohol concentr
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ethanol loading was beyond the maxi
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Table 4-2. Comparison of bioremedia
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Biomass, benzyl alcohol and toluene
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4.4.3 Toluene-ethanol Bioremediatio
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Substrate and biomass concentration
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Biomass and benzyl alcohol concentr
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Biomass and benzoic acid concentrat
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ethanol. These results clearly indi
Page 101 and 102: CHAPTER FIVE - MATHEMATICAL MODELIN
Page 103 and 104: The stoichiometry of the biomass sy
Page 105 and 106: synthesis and in the ethanol catabo
Page 107 and 108: 1 max Y ex = − 0.635 + 2δ + K 3
Page 109 and 110: Biomass Eq.5-18 Benzyl Alcohol Eq.5
Page 111 and 112: r x r N -1.27 -1 0 1 0 0 -0.2 0 0 2
Page 113 and 114: φ = −θ b ⋅ν (5-31) φ b = 1.
Page 115 and 116: The data sets used to evaluate the
Page 117 and 118: Figures 5.4a and 5.4b present 95% c
Page 119 and 120: Ethanol and biomass concentration (
Page 121 and 122: Ethanol measured (C-mol/L) 0.3 0.25
Page 123 and 124: Figures 5.5 (a-d) demonstrate the s
Page 125 and 126: Benzyl alcohol and biomass concentr
Page 127 and 128: Benzyl alcohol measured (C-mol/L) 0
Page 129 and 130: x = 5 ∑ i= 1 x N i (5-40) where x
Page 131 and 132: ethanol in a steady state mode is l
Page 133 and 134: where ν 1 , ν 2 , ν 3, ν 4 are
Page 135 and 136: Biomass concentration, g/L 1.5 1 0.
Page 137 and 138: φ T =ν 4 (5-53b) φx = −ν 1 (5
Page 139 and 140: In this study, a metabolic model ha
Page 141 and 142: Equations (5-34) and (5-35) and the
Page 143 and 144: ATP 1 = Y max ATP r x + m ATP ⋅ C
Page 145 and 146: Ethanol, biomass and ammonium conce
Page 147 and 148: Figure 5-13a shows that the lower t
Page 149 and 150: Biomass, substrate concentrations,
Page 151: C e DKe = (5-63) μ − D m Equatio
Page 155 and 156: Biomass and ethanol concentrations
Page 157 and 158: than 4.0 mg/L at all dilution rates
Page 159 and 160: Biomass, benzyl alcohol and ammonia
Page 161 and 162: negligible ( y out , e = 0) , and e
Page 163 and 164: Figure 5-17 shows the results at a
Page 165 and 166: Biomass Concentrations, g/L 3.5 3 2
Page 167 and 168: C x ( 1 max Q max = ⋅{ D( Cb0 −
Page 169 and 170: 1.2 g/L, the system could not be op
Page 171 and 172: The continuous models can capture a
Page 173 and 174: • Air stripping coefficients obta
Page 175 and 176: Toluene acts as an inhibitor on the
Page 177 and 178: Bruining, W. J., G. E. H. Joosten,
Page 179 and 180: Falatko, D. M., and J. T. Novak, 19
Page 181 and 182: Keuning, S., and D. Jager, 1994.
Page 183 and 184: Orshansky, F., and N. Narkis, 1997.
Page 185 and 186: Togna, A. P, M. Singh, 1994. “Bio
Page 187 and 188: APPENDIX A. Important Metabolic Pat
Page 189 and 190: III. Toluene Pathway (Adapted from
Page 191 and 192: Appendix B. Calibration Procedure a
Page 193 and 194: Figure B-2. Pseudomonas putida (ATC
Page 195 and 196: Appendix B-3. Calibration of Chemic
Page 197 and 198: Appendix B-4. Calibration of Toluen
Page 199 and 200: Appendix C. Experimental Results: A
Page 201 and 202: Probe response time, s 12 10 8 6 4
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Appendix C-2. Fed-batch Operation B
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Appendix D: Mathematical Solutions
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The microscopic model allows the fo
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13δ Y o , = 0.585 2 x = (D-24) (8K
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2 σ = −1.3E − 06 (E-11) Y xe Y
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Biomass, ethanol, and acetic acid c
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Experimental Study of Biodegradation of Ethanol and Toluene Vapors

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