Enhancement of batch butanol production from sugarcane molasses using nitrogen supplementation integrated with gas stripping for product recovery

Initial pH, sugar and nitrogen are important parameters for bio-hutanol production. To improve butanol production efficiency, an L-9 (3(4)) orthogonal array design was used to obtain high levels of butanol production from sugarcane molasses by Clostridium beijerinckii TISTR 1461. The three parameters optimized were initial pH (5.5-7.5), sugar concentration (40-80gl(-1)) and urea level (0.27-1.35gl(-1)). The results showed that the optimal conditions were an initial pH of 6.5, a sugar concentration of 40 gl(-1) and a urea level of 0.81 gl(-1). The magnitude of these parameters' influence on butanol and ABE concentrations was initial pH> sugar > urea. The fermentation under the optimal conditions in a 2-L fermenter with agitation rate of 100 rpm revealed that the butanol and ABE concentrations were 12.55 and 17.96 gl(-1), respectively. Without nutrient supplementation, they were 7.45 and 11.21 gl(-1), respectively, using molasses as a substrate. When a gas stripping system was connected to the fermenter, the butanol and ABE values increased to 14.13 and 18.90 gl(-1), respectively, with butanol productivity and sugar utilization of 0.29 gl(-1) h(-1) and 90.50%, respectively. (C) 2016 Elsevier B.V. All rights reserved.