ANALYTICAL EFFECTIVENESS FACTOR CALCULATIONS CONCERNING PRODUCT-INHIBITED FERMENTATIONS ASSOCIATED WITH BIOFILM GROWTH AND MAINTENANCE

An analytical reaction engineering model, recently presented by van Ed e et al. (1992), which describes formation of inhibiting products asso ciated with the growth of immobilized biofilms, is extended to describ e simultaneous production associated with biofilm maintenance. The mod el accounts for both the metabolic rate controlling behaviour of an in hibitory product in the biofilm, and the effect of diffusion limitatio n in the transport of this product or a substrate, on the biofilm thic kness. Simple criteria are presented to check the applicability of the model in the case of true Monod kinetics. As a potentially industrial ly important example, ethanol production by Zymomonas mobilis is treat ed.