Monday, August 13, 2012
Columbia Hall, Terrace Level (Washington Hilton)
The production of bio-ethanol has been increased in many countries to use as an alternative fuel. Ethanol stillage is a by-product generated after the distillation of ethanol and its amount can be up to 20 liters for each liter of ethanol produced. Because it contains a high amount of organic matter, its proper treatment is necessary. In this study, We report here that thin stillage, a by-product from ethanol fermentation, can be directly used as a medium for butanol production by Clostridium pasteurianum DSM 525 using glycerol as the main carbon source. Using thin stillage for butanol production at initial pH of 4.9-6.9, C. pasteurianum DSM 525 produced 6.2-7.2 g/L of butanol with yields of 0.32-0.44 g of butanol/g of glycerol consumed, which is higher than the yields seen in other reports. Lactic acid in the thin stillage acted as a buffering agent, maintaining the pH of the medium within the range of 5.7-6.5. Lactic acid was also utilized along with glycerol, enhancing butanol production (6.5 g/L butanol vs. 8.7 g/L butanol with 0 and 16 g/L lactic acid, respectively). These results demonstrate an efficient and cost-effective butanol production using thin stillage without any supplementary nutrients and pH control.