Experimental Study of Biodegradation of Ethanol and Toluene Vapors

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Release Inventory (NPRI) are those that contribute to the formation of ground-level ozone and secondary particulate matter. Volatile chemicals produce vapors readily at room temperature and atmospheric pressure. VOCs include gasoline, industrial chemicals such as benzene, and solvents such as toluene and xylene. Many volatile organic chemicals such as benzene and toluene are recognized by the US Environmental Protection Agency (EPA) as hazardous air pollutants. In North America, both Canada and the United States have signed protocols /agreements and have established specific target reductions of VOC emissions and appropriate schedules for implementation. The regulatory incentives are therefore in place for the development and application of cost effective control measures. Toluene ranks high on lists of toxic compounds emitted to the air. In 1993, toluene ranked highest on the Toxics Release Inventory (TRI) “top ten” list of chemicals with large emission rates to the air, with 8.1x10 7 kg/yr of toluene emitted (Reece et al., 1998). Toluene thus accounted for 10.6% of the total TRI released to the air. Sources of these emissions are numerous. Toluene occurs naturally in crude oil, and it is also produced in the process of making gasoline and other fuels from crude oil and making coke from coal. Toluene is used in making paints, paint thinners, fingernail polish, cleaning agents, and in chemical extractions. The major emissions of toluene are released from the plastic manufacturing, car assembly, and printing industries. Ethanol is released to the atmosphere by many different industries such as bakeries, candy, confectionary, food, beverage manufacturing including breweries, and vinegar fermentation (Leson and Winer, 1991). Chemical inventories are generated to determine the quantity and nature of atmospheric emissions, sometime with unexpected 2
esults (van Groenestijn and Hesselink, 1993). For instance, the inventory results indicated that ethanol and hexane account for 90% of the emissions of VOCs from the food and beverage industries (Passant et al., 1992). It was reported that nearly twothirds of the total release of toxic chemicals was emitted to the air (Doerr, 1993). Toluene was chosen in this investigation as the first model air pollutant of VOCs, since it is one of the compounds categorized by the US EPA as a hazardous air pollutant, due to its toxicity and volatility. Ethanol is the second model air pollutant selected for this study, since contrary to toluene it is highly water soluble and easy to bioremediate. As for any pollution control technology, the major driving force for development of biological VOC treatment technologies is the continued extension and implementation of air pollution control regulations. In addition, biological VOC treatment technologies are viewed as pollution prevention or green technologies. The stirred tank reactor has been selected in this study due to its being a popular biochemical experimental setup with the following positive characteristics: 1) efficient biomass retention; 2) a homogeneous distribution of substrates, products and biomass aggregates over the reactor; 3) reliable, continuous operation for more than 1 year; and 4) stable conditions under substrate-limiting conditions (Strous et al., 1998). Since ethanol is miscible with water, the stirred tank reactor (acting as a bioscrubber) may represent the best choice for treatment of ethanol contamination in the air. Once ethanol is available in the aqueous phase, the bacteria will be able to degrade it. Existing gas phase bioreactors such as biofilters can not treat high concentrations of toluene vapor in the air due to its high toxicity. In addition, a major disadvantage of biofilters, limiting 3
Page 1 and 2: BIOREMEDIATION OF VOLATILE ORGANIC
Page 3 and 4: ABSTRACT The mass transfer of ethan
Page 5 and 6: effect on the growth of P. putida.
Page 7 and 8: ACKNOWLEDGMENT Of the countless peo
Page 9 and 10: TABLE OF CONTENTS PERMISSION TO USE
Page 11 and 12: 4.3 Batch Growth on Ethanol and Ben
Page 13 and 14: LIST OF FIGURES Figure 3-1. Schemat
Page 15 and 16: Figure 5.3 (b) Simulation of ethano
Page 17 and 18: Figure 5-16. Continuous removal of
Page 19 and 20: NOMENCLATURE a - Interfacial area,
Page 21: CHAPTER ONE - INTRODUCTION 1.1 Air
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
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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.
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The data sets used to evaluate the
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Figures 5.4a and 5.4b present 95% c
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Ethanol and biomass concentration (
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Ethanol measured (C-mol/L) 0.3 0.25
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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
Page 177 and 178:
Bruining, W. J., G. E. H. Joosten,
Page 179 and 180:
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
Page 191 and 192:
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
Page 197 and 198:
Appendix B-4. Calibration of Toluen
Page 199 and 200:
Appendix C. Experimental Results: A
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Probe response time, s 12 10 8 6 4
Page 203 and 204:
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
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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