Experimental Study of Biodegradation of Ethanol and Toluene Vapors

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k L a=-0.00285+0.00214[E]-0.0118[E] 0.5 +3.595x10 -5 N-1.587x10 -5 [E]N +8.741x10 -5 [E] 0.5 N for 135 ≤ N ≤ 600 rpm, 0≤ [E] ≤ 8 g/L (4-7) where [E] is ethanol liquid concentration (g/L), N is agitation speed (rpm). It is apparent from Equation (4-7) that both individual and interacting effects are significant for stirring speed and ethanol concentration. The smaller bubble diameters generated at high impeller speeds and with the addition of a small quantity of ethanol increase both the gas holdup and the gas-liquid interfacial area. Both features improve the mass transfer rate of oxygen into the liquid phase. Thus it is clear that the addition of a small amount of ethanol to an actual fermentation process has the potential to enhance the rate of biomass build-up and even the total amount of biomass produced inside the bioreactor. The volumetric mass transfer coefficient, average bubble diameter and gas holdup in a well-mixed fermentor were found to be dependent on impeller speed and ethanol concentration. Both k L a and gas holdup increased with increasing impeller speed and ethanol concentration in pure water. The average bubble diameter decreased with increasing impeller speed and ethanol concentration in the distilled water. The oxygen mass transfer coefficients have been successfully modeled using empirical correlations. 4.2 Air Stripping The air stripping parameters (β values as per Singh and Hill, 1987) were determined by performing a brief experiment with no microbial inoculation using the 54
Bioflow III bioreactor. Equation (4-8) describes the relation between substrate concentration in the liquid phase and time (Singh and Hill, 1987): S0 ln( ) = β ⋅ S t (4-8) where S o and S represent the substrate concentrations at time zero and time t. By plotting ln(S 0 /S) versus t, the slope of the straight line will give the air stripping parameter (β). The ethanol air stripping studies were conducted at an initial liquid ethanol concentration of 8.6 g/L, impeller speed of 450 RPM, and temperature of 25.0 º C, while varying air flow rates through the well–mixed bioreactor. The ethanol air stripping parameters (β values) were determined (See Figures 4-5) to be 0.002 and 0.007 h -1 for air flow rates of 0.4 L/min (0.3 vvm) and 1.4 L/min (1 vvm), respectively. The toluene air stripping rates (See Figure 4-6), at initial liquid toluene concentration of 440 mg/L, were found to be 2.2, 5.3, 10.4, and 12.6 h -1 for air flow rates of 0.4, 0.9, 1.4, 2.1 L/min, respectively. The results show that the air stripping parameter increases with the increase of air flow rates as predicted by Singh and Hill (1987), and stripping rates obtained in this study for ethanol were much lower than those for toluene. It was also observed that benzyl alcohol was not stripped to any detectable level at any of the operating conditions used in this study. In order to minimize the air stripping effects during batch and continuous bioremediation studies, the air flow rate was maintained at a low value of 0.4 L/min (0.3 vvm) during all bioremediation studies. 55
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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
Page 23 and 24: esults (van Groenestijn and Hesseli
Page 25 and 26: experimental results are presented
Page 27 and 28: Table 2.2 VOC Emissions in the U.S.
Page 29 and 30: (paint shop effluents, for instance
Page 31 and 32: combustion provides 70 to 90% air p
Page 33 and 34: used to degrade ethanol vapours and
Page 35 and 36: g m -3 . This would suggest that th
Page 37 and 38: treatment, This excessive biomass f
Page 39 and 40: The simultaneous degradation of tol
Page 41 and 42: emoves only water-soluble gases. Wa
Page 43 and 44: 2.2.6 Pseudomonas It is well known
Page 45 and 46: 2.3.2 Growth Models with Inhibition
Page 47 and 48: where µ is the total specific grow
Page 49 and 50: 2.4.1 Batch Reactor In a batch reac
Page 51 and 52: discharged from the other end. The
Page 53 and 54: element solution consisted of (gram
Page 55 and 56: growth on ethanol, 20-48 hours for
Page 57 and 58: Gas phase samples of toluene were c
Page 59 and 60: Inlet sampler Exit sampler To fume
Page 61 and 62: Once the oxygen meter indicated a s
Page 63 and 64: centrifuged and the supernatant was
Page 65 and 66: where k L a is the volumetric mass
Page 67 and 68: Figure 4-2a shows ethanol liquid co
Page 69 and 70: coefficient (k L a) in the well-mix
Page 71 and 72: calculated by dividing the gas volu
Page 73: Average bubble diameter, mm 8 7 6 5
Page 77 and 78: 3.5 y=Ln(S0/S) 3 2.5 2 1.5 1 y = 12
Page 79 and 80: Ethanol and biomass concentration,
Page 81 and 82: 4.3.2 Batch Growth on Benzyl Alcoho
Page 83 and 84: Biomass and benzyl alcohol concentr
Page 85 and 86: ethanol loading was beyond the maxi
Page 87 and 88: Table 4-2. Comparison of bioremedia
Page 89 and 90: Biomass, benzyl alcohol and toluene
Page 91 and 92: 4.4.3 Toluene-ethanol Bioremediatio
Page 93 and 94: Substrate and biomass concentration
Page 95 and 96: Biomass and benzyl alcohol concentr
Page 97 and 98: Biomass and benzoic acid concentrat
Page 99 and 100: 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
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Benzyl alcohol and biomass concentr
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Benzyl alcohol measured (C-mol/L) 0
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x = 5 ∑ i= 1 x N i (5-40) where x
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ethanol in a steady state mode is l
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where ν 1 , ν 2 , ν 3, ν 4 are
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Biomass concentration, g/L 1.5 1 0.
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φ T =ν 4 (5-53b) φx = −ν 1 (5
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In this study, a metabolic model ha
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Equations (5-34) and (5-35) and the
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ATP 1 = Y max ATP r x + m ATP ⋅ C
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Ethanol, biomass and ammonium conce
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Figure 5-13a shows that the lower t
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Biomass, substrate concentrations,
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C e DKe = (5-63) μ − D m Equatio
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corresponds with the value associat
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Biomass and ethanol concentrations
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than 4.0 mg/L at all dilution rates
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Biomass, benzyl alcohol and ammonia
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negligible ( y out , e = 0) , and e
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Figure 5-17 shows the results at a
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Biomass Concentrations, g/L 3.5 3 2
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C x ( 1 max Q max = ⋅{ D( Cb0 −
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1.2 g/L, the system could not be op
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The continuous models can capture a
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• Air stripping coefficients obta
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Toluene acts as an inhibitor on the
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Bruining, W. J., G. E. H. Joosten,
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Falatko, D. M., and J. T. Novak, 19
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Keuning, S., and D. Jager, 1994.
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Orshansky, F., and N. Narkis, 1997.
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Togna, A. P, M. Singh, 1994. “Bio
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APPENDIX A. Important Metabolic Pat
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III. Toluene Pathway (Adapted from
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Appendix B. Calibration Procedure a
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Figure B-2. Pseudomonas putida (ATC
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Appendix B-3. Calibration of Chemic
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Appendix B-4. Calibration of Toluen
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Appendix C. Experimental Results: A
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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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