Optimization of the Cyclic Operation of a Continuous Biobutanol Fermentation Process Integrated with Ex-Situ Adsorption Recovery

Biobutanol has received significant attention as a renewable gasoline substitute and as a chemical feedstock owing to its high energy content, low volatility, and low water solubility. Low volumetric productivity caused by the toxicity of butanol in batch fermentation stands as one of the major obstacles to the commercialization. In this paper, continuous biobutanol fermentation with ex-situ adsorption recovery of butanol is investigated as a way to overcome this limitation. In this integrated system, the spatial segregation of the adsorption system and the fermentation process enables continuous biobutanol production without the need to stop the fermentation. Since the adsorption column needs to be switched periodically owing to the limited capacity of the adsorbent, the overall operation follows a cyclic pattern and the fermentation process converges to a cyclic steady state (CSS). In this study, a dynamic model of the integrated process is constructed and used for dynamic simulation to determine the system. Major operating variables are optimized through grid search for given feed concentrations based on the predicted CSS behavior in order to design an operation strategy that satisfies given requirements.