Assessment of options for selective 1-butanol recovery from aqueous solution

The microbial production of 1-butanol occurs in aqueous fermentation broth, with up to ∼20 g/L of product. Efficient recovery of butanol from this dilute aqueous phase determines, to a large extent, the efficiency of the production process. Starting from the thermodynamic (phase) properties of butanol and water systems, this paper presents a structured approach to determine the key characteristics of various butanol recovery methods. Analysis of reported separations, combined with fundamental phase properties, has resulted in both the characterization of the selectivity of recovery and estimations of the energy requirement during product recovery for a variety of recovery methods. Energy-efficient systems for the recovery of butanol from aqueous solution are pervaporation-and adsorption-based techniques. The applied method predicts the recovery energy requirement for both techniques to be <4 MJ/kg of butanol, which, on an energy basis, is similar to ∼10% of the internal combustion energy of butanol.