Direct Production of Butanol and Ethanol from Cane Sugar Factory Wastewater and Cellulosic Ethanol Pilot Plant Wastewater by Clostridium Beijerinckii CG1

Abstract

The ability of Clostridium beijerinckii CG1 to utilize sugar from cane sugar factory wastewater (CSFW) and cellulosic ethanol pilot plant wastewater (CEPW) as a renewable carbon source and complete fermentation medium to produce acetone-butanol-ethanol (ABE) was investigated. CSFW and CEPW were used as the unsupplemented culture media (50mL) for ABE production by C. beijerenckii CG1 fermentation in 100-mL serum bottles. No acetone was produced from fermentation of either CEPW or CSFW, in contrast to the small amount (20g L-1) produced from glucose in the last 24h of a 120h fermentation. The average ethanol, butanol and butyric acid production from CEPW (butanol 0.6g L-1, ethanol 0.4g L-1 and butyric acid 2.5g L-1) was higher than that from CSFW (butanol 0.3g L-1, ethanol 0.3g L-1 and butyric acid 0.9g L-1), but still less than that from glucose (butanol 1.87g L-1, ethanol 0.86g L-1 and butyric acid 6.47g L-1). However, the productivity rate in this 50-mL fermentation was three-fold higher with CSFW (0.06g L-1 h-1) than with CEPW (0.02g L-1 h-1). These results suggest that CSFW and CEPW can be applied as appropriate substrates to produce solvents by C. beijerinckii CG1 at a reasonable concentration without the need for additional exogenous nutrient supplements or pretreatment. The idea then being to consolidate the bioprocess for low-cost biofuel production.