Performance of tapered-column packed-bed bioreactor used for ethanol production by immobilized yeast cells
The tapered-column packed-bed bioreactor was tested as a solution to the problems of pressure drop and nonuniform flow in immobilized-yeast fermentations. The column operation was simulated using a mathematical model considering the effects of the heterogeneous kinetics, interfacial mass transfer, convective and dispersive flows of the liquid phase. The kinetics of ethanol production by the immobilized Saccharomyces cerevisiae was determined using shake-flask batch cultures. It was found that there is a shift in the metabolism of the yeast used at glucose concentrations of about 2 to 5 g/l, and due to this effect two sets of V/sub m/ and K/sub m/ values are determined. Maximum rate of fermentation was found to be 0.80 and 0.39 g ethanol/g cell/hr, and the affinity constant was found to be 97 and 11 mM in the medium and low glucose concentration regions respectively. The rate of fermentation went through a maximum at about 70 g glucose/l and the substrate inhibition constant was found to be 0.76 M. The product inhibition constant was also tested and was found to be 113 g ethanol/l. The column performance was simulated effectively at low residence times and low ethanol concentrations, however at the larger residence times and product concentrations better agreement was obtained by changing the ethanol inhibition constant to 85 g/l. In another set of experiments the effect of inert gas flow and oxygen gas feed into the tapered-column was tested. Inert gas feed helps increase the conversion only at very small flow rates. The effect of oxygen was positive at all the flow rates tested.
- Research Organization:
- California Univ., Davis (USA)
- OSTI ID:
- 6887910
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BIOREACTORS
PERFORMANCE TESTING
ETHANOL
BIOSYNTHESIS
SACCHAROMYCES CEREVISIAE
BATCH CULTURE
BIOCHEMICAL REACTION KINETICS
FLUID FLOW
GLUCOSE
IMMOBILIZED CELLS
INHIBITION
MASS TRANSFER
MATHEMATICAL MODELS
OXYGEN
PRESSURE DROP
SIMULATION
YIELDS
ALCOHOLS
ALDEHYDES
CARBOHYDRATES
ELEMENTS
FUNGI
HEXOSES
HYDROXY COMPOUNDS
KINETICS
MICROORGANISMS
MONOSACCHARIDES
NONMETALS
ORGANIC COMPOUNDS
PLANTS
REACTION KINETICS
SACCHARIDES
SACCHAROMYCES
SYNTHESIS
TESTING
YEASTS
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