Butanol production by Clostridium acetobutylicum in a continuouspacked bed reactor

The study reports on a butanol production process by immobilized Clostridium acetobutylicum in a continuous packed bed reactor (PBR) using Tygon® rings as a carrier. The medium was a solution of lactose (15–30 g/L) and yeast extract (3 g/L) to emulate the cheese whey, an abundant lactose-rich wastewater. The reactor was operated under controlled conditions with respect to the pH and to the dilution rate. The pH and the dilution rate ranged between 4 and 5, the dilution rate between 0.54 and 2.4 1/h (2.5 times the maximum specific growth rate assessed for suspended cells). The optimal performance of the reactor was recorded at a dilution rate of 0.97 1/h: the butanol productivity was 4.4 g/Lh and the selectivity of solvent in butanol was 88%w.