Mathematical model of microporous hollow-fiber membrane extractive fermentor

A mathematical model is presented for a microporous hollow-fiber membrane extractive fermentor (HFEF). The model is based on the continuous flow of the aqueous nutrient phase and cells through the shell space of the fermentor where the fermentation reaction occurs. The product diffuses from the shell space through the hollow-fiber membrane where it is continuously removed by solvent flowing concurrently through the fiber lumen. Results for ethanol production show that the HFEF has a volumetric productivity significantly higher than that possible using conventional methods. The model predicts the existence of an optimum volume fraction of hollow fibers in the fermentor that maximizes the total volumetric productivity. This optimum is the result of a classic trade-off between the volume fraction of the fermentor required for fermentation and that required for efficient removal of the ethanol product to minimize product inhibition.