Modeling and Optimization of a Fermentation Process Integrated with Cell Recycling and Pervaporation for Multiple Objectives

Biofuels have potential to replace fossil fuels as a clean energy source. Bioethanol and biodiesel are the most commonly produced biofuels. Bioethanol is produced by fermenting sugar components of biomass (e.g., sugarcane, corn, cellulosic materials). Although ethanol production using sugar and starch as feedstocks is well established, it can still be improved. Ethanol concentration in the fermentor inhibits conversion of fermentable sugars to ethanol, which results in low yield and productivity; these can be improved by better fermentation kinetics and/or process design. Ethanol can be removed from the fermentor by using extraction or a membrane process. Recently, bioethanol production process with interstage extraction has been optimized. The present work models and optimizes a three-stage bioethanol process integrated with cell recycling and pervaporation for multiple objectives using multiobjective differential evolution. The integrated process, with glucose and xylose as feedstocks, has been optimized for both ethanol productivity and xylose conversion simultaneously. The performance of the three-stage fermentation process integrated with pervaporation is compared with the three-stage fermentation process integrated with extraction, and the former is found to be better. The net flow method is used to rank the obtained nondominated solutions for the three-stage fermentation process integrated with cell recycling and pervaporation.