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

• Sugarcane molasses was a suitable substrate for butanol production.
• Urea could be used instead of yeast extract for butanol production.
• Initial pH, sugar and urea markedly affected butanol production from molasses.
• Gas stripping was successfully used to improve butanol production efficiency.

Initial pH, sugar and nitrogen are important parameters for bio-butanol production. To improve butanol production efficiency, an L9 (34) 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 (40–80 g l−1) and urea level (0.27–1.35 g l−1). The results showed that the optimal conditions were an initial pH of 6.5, a sugar concentration of 40 g l−1 and a urea level of 0.81 g l−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 g l−1, respectively. Without nutrient supplementation, they were 7.45 and 11.21 g l‐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 g l−1, respectively, with butanol productivity and sugar utilization of 0.29 g l−1 h−1 and 90.50%, respectively.