Improving n-butanol production in batch and semi-continuous processes through integrated product recovery

Although it represents a promising biofuel, n-butanol production by conventional batch fermentation is limited as a result of its cytotoxic effects. To address this limitation and facilitate semi-continuous fermentation, in situ n-butanol removal has proven to be an effective approach. Exploiting the phenomena of solvent extraction, adsorption, or vaporization, numerous integrated bioprocess configurations have been developed to facilitate selective n-butanol recovery. The objective of this review is to provide a broad overview of different technology options and process configurations to this end, highlighting notable achievements and recent developments. In each case, relevant design considerations critical for improving key production metrics will be discussed, with particular emphasis given to studies that, as a result of relieved product toxicity, have successfully demonstrated further enhanced n-butanol production through semi-continuous operation.