Experimental Study of Biodegradation of Ethanol and Toluene Vapors

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4.4 Continuous Bioremediation 4.4.1 Ethanol Bioremediation Pseudomonas putida was initially grown in a batch culture which contained an initial dissolved ethanol concentration of 2.6 g/L. After 11 hours, when the ethanol was completely consumed and the biomass concentration reached a certain level, the medium pump was started at a flow rate of 150 mL/h (dilution rate of 0.1 h -1 ) and ethanol was continuously added at an air inlet concentration of 15.9 mg/L and flow rate of 0.37 L/min (ethanol loading of 235 mg/L-h). Figure 4-11 demonstrates that the ethanol transferred from the polluted air stream was continuously utilized by Pseudomonas putida. After operating for 25 hours, the inlet ethanol concentration was increased to 19.5 mg/L (air flow rate to 0.39 L/min accordingly; ethanol loading of 304 mg/L-h). The bioreactor was again operated at steady state for another 25 hours before shutting down the bioreactor in order to study other operating conditions. During the steady state operations, there was no ethanol detected from the outlet gas stream. Figure 4-12 shows the results for another independent continuous run. After operating for 38 hours at an inlet ethanol concentration of 15.9 mg/L and air flow rate of 0.37 L/min (ethanol loading of 235 mg/L-h), the ethanol inlet concentration was increased to 25.0 mg/L and the air flow rate was increased to 0.42 L/min (ethanol loading of 420 mg/L-h). The biomass concentration and the media pH started to decrease while acetic acid was detected in the liquid phase (identified by GC-MS, Model VG70VSE, VG Analytical). Dissolved oxygen indicated a value of 0 mg/L at this condition. Instead of being completely converted to biomass, ethanol was only partially converted to acetic acid and then excreted into the media when the inlet 64
ethanol loading was beyond the maximum uptake rate of the cells due to oxygen limitation. There was no detectable ethanol bypassing the reactor in gas phase under all the above operating conditions. Ethanol and biomass concentration, g/L 3 2.5 2 1.5 1 0.5 0 Cgin =15.9 mg/L Cgin =19.5 mg/L 0 20 40 60 Time, h X(batch start) X at Cgin = 19.5 mg/L X at Cgin = 15.9 mg/L ethanol in liquid Figure 4-11. Continuous removal of ethanol from a polluted gas stream by Pseudomonas putida at a dilution rate of 0.1h -1 and 25.0°C, and at inlet ethanol concentrations of 15.9 and 19.5 mg/L (no detectable ethanol or acetic acid in the liquid) 65
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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
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 and 74: Average bubble diameter, mm 8 7 6 5
Page 75 and 76: Bioflow III bioreactor. Equation (4
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: Biomass and benzyl alcohol concentr
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
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
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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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