Optimization of Solvent Recovery in the Production of Butanol by Fermentation

The current energetic scenario has revived the interest for Acetone-Butanol-Ethanol (ABE) fermentations. An open issue is represented by the recovery process of ABE from the fermentation broth, which van be extremely expensive due to the low concentration of products that establish during the fermentation. Since the ABE production kinetics is characterized by product inhibition, the ABE concentration in the bioreactor is typically smaller than 20g/L. The present work reports on the assessment of a cost-effective flow-sheet for the recovery of butanol produced by fermentation. The study is based on approximated cost-estimation methods integrated with the simulation software Aspen Plus®. The recovery line investigated includes gas-stripping, absorption of butanol in a selected liquid phase, distillation to separate the butanol from the selected liquid. The design variables are selected so as to correspond to the degrees of freedom of the process. A preliminary determination of plausible values of the venture profit of the process has been attempted as a function of operating conditions.