(546e) Cell Growth Model in a Pervaporation Membrane Bioreactor for Continuous Ethanol Fermentation By Saccharomyces Cerevisiae

Coupling pervaporation with ethanol fermentation, ethanol is in situ removed from the broth by the pervaporation membranes and the inhibition of ethanol can be released or even eliminated. High cell density and high ethanol production can be achieved in the continuous closed-circulating fermentation (CCCF) system with a pervaporation membrane bioreactor for ethanol fermentation. A dynamic model was proposed to describe the cell growth in CCCF system. In the model, the secondary metabolites accumulated in the broth not permeating though the membranes was considered as the main inhibitors and the inhibition of these compounds could be described as a function of ethanol production with the fermentation process proceeded. The cell death rate related to the deterioration of the culture environment in the pervaporation membrane bioreactor was described as a function of the integration of all values of the population density. High ethanol fermentation production could be explained by the model, since long fermentation time was last for these secondary metabolites accumulated to the point where they could completely inhibit the cell growth and the phase of decline after the stationary population could be also predicted well. The model was validated by the simulation results of the dynamic model agreeing well with the experimental data.