ANALYSIS OF A TWO-STAGE FERMENTOR WITH RECYCLE FOR CONTINUOUS ETHANOL PRODUCTION

The performance of a recycle two-stage fermentor with cell separators after each stage is analyzed numerically for the continuous production of ethanol. In this system, the bleed withdrawn from the first stage is introduced to the second tank in order to reuse the cells in the bleed. Kinetic expressions and parametric values are taken from the literature. The effects of operating parameters on the concentrations in the stages are examined. Also investigated are the critical dilution rate for washout, the ethanol productivity and the substrate conversion. In addition, the influences of the saturation constant and the equilibrium partition coefficient of ethanol are examined. With respect to the overall productivity and conversion, it is found that the present two-stage system is more efficient than either a recycle chemostat or a recycle two-stage fermentor with a single separator after the final stage.