Experimental Study of Biodegradation of Ethanol and Toluene Vapors

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5.6.4 Theoretical Predictions of Continuous Steady State Removal of Benzyl Alcohol and Toluene Mixtures For growth with the benzyl alcohol/toluene mixture, toluene acts as a growth inhibitor only (Bailey and Ollis, 1986; Chang et al, 1993; Bielefeldt and Stensel, 1999). The growth on the mixture of benzyl alcohol and toluene follows the two-compound inhibition equation (Bailey and Ollis, 1986) which agrees with the metabolic model that applied with the data for benzyl alcohol/toluene bioremediation: μ C C max b b n μ = (1 − ) (5-72) Cb + K b ( 1+ I / K i ) Cb, max where μ max = μ e,max , I = liquid concentration of a competing compound (mg/L) and K i is an inhibition constant (mg/L). In this case, I = C t , K i = 1.71mg / L for toluene was used (Chang et al., 1993). For benzyl alcohol (see Table 5.2): μ = 0. 42 h -1 , and K b = 0.289g / L . The biomass concentration can be predicted by: m C x 1 max tx bt = max ⋅ ( φb ⋅Ybx + T ⋅Y ( μ + m ) φ ) (5-55) φ b and φ T represent the net amount of benzyl alcohol and toluene that flows into the system (In-Out), and they are calculated using the following equations: F( Cb0 Cb ) φ − b = (5-55a) V Q( yin, T − yout, T ) F( CT 0 − CT ) Q φ T = + = ( yin, t − yout, t ) − DCT (5-49b) V V V Therefore, the expression of biomass concentration becomes: 146
C x ( 1 max Q max = ⋅{ D( Cb0 − Cb ) ⋅Ybx + [ ( yin, t − yout, e ) − DCt ] ⋅Ytx } μ + met ) V (5-73) Equations (5-72), and (5-73) are applied to predict benzyl alcohol, and biomass concentrations for the steady state continuous removal of benzyl alcohol and toluene mixtures. Figures 5-19 and 5-20 show the predicted results of biomass (X), benzyl alcohol (C b ) concentrations, and the DO level (calculated from Equation 5-68) as a function of dilution rate and feed concentration. Figure 5-19 demonstrates that at a benzyl alcohol inlet concentration of 0.6 g/L, the system can be operated at steady state conditions for toluene gas inlet concentrations up to 12.0 mg/L. The results show that with increasing dilution rates, the biomass concentration (X) decreases and that the system can be operated at dilution rates up to 0.21 h -1 with the DO levels above 0.87 mg/L. Therefore, oxygen mass transfer is not the rate-limiting factor at these conditions. When the dilution rate is higher than 0.21 h -1 , cells are washed out, and no consumption occurs. At these dilution rates, the benzyl alcohol concentration equals the feed concentration (C b = C b0 ), toluene in the liquid phase reaches equilibrium with the gas phase, and the gas outlet toluene concentration reaches the same level as the gas inlet concentration (y t = y t,in ). The predicted results also indicate that at benzyl alcohol feed concentration of 0.6 g/L, the system could not be operated at steady state when the toluene gas inlet is higher than 12.0 mg/L unless an oxygen-enriched air is used as the oxygen supply. 147
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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
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CHAPTER FIVE - MATHEMATICAL MODELIN
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The stoichiometry of the biomass sy
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synthesis and in the ethanol catabo
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1 max Y ex = − 0.635 + 2δ + K 3
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Biomass Eq.5-18 Benzyl Alcohol Eq.5
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r x r N -1.27 -1 0 1 0 0 -0.2 0 0 2
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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 and 152: C e DKe = (5-63) μ − D m Equatio
Page 153 and 154: corresponds with the value associat
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: Biomass Concentrations, g/L 3.5 3 2
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
Page 203 and 204: Appendix C-2. Fed-batch Operation B
Page 205 and 206: Appendix D: Mathematical Solutions
Page 207 and 208: The microscopic model allows the fo
Page 209 and 210: 13δ Y o , = 0.585 2 x = (D-24) (8K
Page 211 and 212: 2 σ = −1.3E − 06 (E-11) Y xe Y
Page 213: Biomass, ethanol, and acetic acid c
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Experimental Study of Biodegradation of Ethanol and Toluene Vapors

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