Bioethanol Production from Bagasse

• Main Authors: Wei-Jen Chen, 陳韋任
• Other Authors: Jyh-Cherng Shieh
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/23191608141211998064

碩士 === 臺灣大學 === 生物產業機電工程學研究所 === 95 === Bioethanol is a kind of clean and renewable energy which can be used directly or mixed with gasoline as fuel on vehicles. In this study, sugarcane bagasse which contained 33.34% cellulose, 22.11% semicellulose, and 6.49% lignin was pretreated by 0.25 M sulfuric acid under 95℃ and 1 atm pressure for 60 mins. After pretreatment, dried solid material was hydrolyzed by mixing enzymes of cellulase from Trichoderma reesei C2730 (Celluclast 1.5L) and cellobiase from Aspergillus niger (Novozyme 188) under conditions of pH 4.6, 50℃ in 80 rpm shaking water bath for 24 hours. Different enzyme loadings and substrate ratios were tested to find out the optimum parameters. Hydrolysate was then fermented with Saccharomyces cerevisiae BCRC 21685 under conditions of pH 4.6, 30℃ for 24-48 hours. The effect of additional glucose, sterilization, and detoxification were investigated in this step. As result, 0.52 mg/mL of glucose and 4.29 mg/mL of xylose concentrations were observed in liquid fraction and the content of solid material showed that 91.85% semicellulose and 1.46% cellulose was removed in pretreatment. In hydrolysis step, the enzyme loading of 5 mL Celluclast 1.5L plus 1 mL Novozyme 188 represented the best balance between economy and efficiency. 339.21 mg/mL of yield and 49.25% of conversion ratio were obtained under this enzyme loading with 1% substrate ratio and rising the substrate ratio did not help improving both of them. In fermentation step, without sterilization and detoxification, 26.7 g/L of glucose remains after 48 hours fermentation and ethanol yield was 0.367 g ethanol / g glucose, corresponding to 72% of theoretical ethanol yield. With sterilization and detoxification, glucose was fermented within 24 hours. The ethanol yield was 0.43 g ethanol/g glucose, , corresponding to 84% of theoretical ethanol yield. With evaporation to enhance the glucose concentration, the glucose concentration did not decrease to zero until after 30h. The ethanol concentration was 40.7 g/L, corresponding to 79% of theoretical ethanol yield.