Comparison of in-situ recovery methods of gas stripping, pervaporation, and vacuum separation by multi-objective optimization for producing biobutanol via fermentation process

Acetone, butanol, and ethanol (ABE) continuous fermentation for biobutanol production was simulated and optimized for three case studies where the ABE fermentation process was integrated in turn with gas stripping, pervaporation, and vacuum separation methods in an attempt to partly mitigate the product inhibition effect. Following the multi-objective optimization of the three integrated processes, the Pareto-optimal solutions were ranked using the net flow method to determine the best operating conditions. Results were compared to a standard continuous fermentation process without an integrated recovery method. The integrated butanol recovery methods improved butanol productivity by a factor of 6-10, and sugar conversion by a factor of 3, while butanol yield remained essentially unchanged. In addition, the butanol average concentration based on all exit streams for the fermentation process integrating one of the separation methods is approximately 2.25 times higher when compared to the non-integrated fermentation process, with values in the vicinity of 30g/L. Results of the gas stripping and vacuum fermentation processes were very similar to each other but superior to pervaporation in terms of butanol productivity and average concentration.