Dilute Acid Hydrolysis of Sugarcane Bagasse for Butanol Fermentation

This research was concerned with butanol production from fermentation of sugarcane bagasse hydrolysate by Clostridium sp. Initially, sugarcane bagasse was treated using a ball mill in order to investigate the effects of mechanical treatment on particle size distribution. Size reduction of sugarcane bagasse by ball milling was carried out for a period of time within a range of 2-8 hours at room temperature. The optimal ball milling time was considered to be 2 hours, which resulted in a yield of 43% for the size range of sugarcane bagasse particles of 1180-212 mu m. Then, the sugar hydrolysis was tested at various temperatures (30, 70, 80, 121 C), particle size ranges of sugarcane bagasse, ratios of sugarcane bagasse to solvent (1: 10, 1: 15, 1: 20) and H 2 SO 4 concentrations (0.25-1% by volume). The optimum conditions for acid hydrolysis, which yield the maximum reducing sugar concentration of about 52 g/l, were particle size of 0.212-1.180 mm, sugarcane bagasse-to-solvent ratio of 1: 10, H 2 SO 4 concentration of 1% by volume and temperature of 121 C for 1 hour. Finally, the fermentation of sugarcane bagasse hydrolysate by Clostridium sp. affecting yield of butanol, ethanol and acetone production was studied. This work was carried out using various types of Clostridium sp., including Clostridium butyricum (TISTR 1032), Clostridium sporogenes (TISTR 1452), Clostridium beijerinckii (TISTR 1461) and Clostridium acetobutylicum (TISTR 1462). The results showed that 24h-butanol fermentation of sugarcane bagasse hydrolysate by Clostridium beijerinckii (TISTR 1461) gave the highest butanol concentration of 0.27 g/l.