Optimal design and operation of an extractive fermentation process for continuous biobutanol production

Biobutanol is considered to be a promising choice for renewable fuel due to its high energy content, low volatility, and low water solubility. However, the production of biobutanol through fermentation is complicated by the fact that butanol inhibits the microorganism's cell growth and therefore the butanol production when its concentration in the fermentation broth reaches a certain critical level. In order to raise the volumetric productivity to a commercially acceptable level, produced biobutanol needs to be separated out as the fermentation is on-going. In this study, a continuous extractive fermentation process integrated with an ex-situ adsorption recovery process is studied to overcome this limitation. Switching of the adsorption column upon the saturation yields a continuous process with a cyclic steady state behavior. A dynamic model for the integrated process is developed and an optimization is performed based on the cyclic steady state analysis in order to design an optimal operation strategy that satisfies given requirements.