A novel integrated fermentation/recovery system for butanol production by Clostridium acetobutylicum

Intensive butanol production was carried out by immobilized cells of Clostridium acetobutylicum in a novel continuous fermentation system. The fermentation system consisted of four packed bed biofilm reactors (PBBR) connected in series. The novelty of the proposed system is: i) the use of a novel stagewise simulated moving bed (SMB) design/operational mode; ii) the integration of the reaction and the product recovery sections. The SMB operational mode was accomplished by equipping the PBBR with manifolds and time-actuated switching valves. PBBR integration with the product recovery section was also tested. An adsorption column was operated between the 3rd and 4th reactor of the series. The tuning of the PBBR system overall dilution rate (DOV) allowed to maximize: i) sugar conversion (DOV <0.150 h−1); ii) butanol concentration (0.650 h−1< 0.900 h−1); iii) butanol productivity (13.0 g/Lh at DOV = 0.900 h−1). The PBBR system was upgraded by integrating it with an in-line adsorption column and it guaranteed a twofold increase in butanol productivity (up to 22 g/Lh) and an average butanol concentration close to 24.0 g/L.