Butanol production from the effluent of hydrogen fermentation.

The purpose of the study was to recover butanol from the effluent of the hydrogen-producing bioreactor containing acetate, butyrate, and carbohydrate. The butanol production by Clostridium beijerinckii NRRL B592 was evaluated under both unsterilized and sterilized conditions for examining the potential of butanol production for the practical application. Sucrose of 10 g/L and butyrate of 2 g/L coupled with acetate buffer were used to mimic the effluent. Sucrose was completely consumed in the both unsterilized and sterilized conditions during acetone-butanol-ethanol (ABE) fermentation. However, the results illustrate that the carbohydrate consumption rate in the unsterilized condition was higher than that in the sterilized condition. The maximum butanol concentrations of 3,500 and 3,750 mg/L were achieved in the sterilized and unsterilized conditions, respectively. Meanwhile, it was found that the acetate and the butyrate concentrations of 600 and 1,500 mg/L, and 300 and 1,000 mg/L were ingested to yield butanol in the sterilized condition and in the unsterilized condition, respectively. The results concluded that high levels of acetate and butyrate could eliminate the interference of other microbial populations, resulting in the enrichment of C. beijerinckii NRRL B592 in the fermentor. The butanol production by C. beijerinckii NRRL B592 could be, therefore, produced from the effluent of the hydrogen-producing bioreactor. It promised that the microbial butanol production is one of attractive bioprocesses to recover energy from wastes.