A Strategy for Hydrogen – Ethanol Switch in Anaerobic Fermentation

• Main Authors: Ya-Chun Cheng, 鄭雅淳
• Other Authors: Chiu Yue Lin
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/68248478125490330017

碩士 === 逢甲大學 === 環境工程與科學所 === 98 === Hydrogen and ethanol are attractive biofuels. Hydrogen is the cleanest and high energy content (122 kJ/g) energy carrier; bioethanol is a good alternate for the gasoline fuels of vehicles. Using these two bioenergy could reduce greenhouse gas emissions. Hydrogen is an intermediate product during anaerobic fermentation; soluble metabolic products e.g., ethanol are produced at the same time. This study aimed to establish the operating technology to obtain the maximum bioenergy production efficiency at the same reactor. The effects of hydrogen and ethanol production by shifted the pH and nutrient formula conditions were investigated in continuously stirred tank reactors (CSTR). pH was shifted from 6.8 to 6.0 and 6.8 to 5.0 back and forth, respectively, in the reactor. Then the reactor was operated in on optimal condition again. The optimal condition for hydrogen production yield (HY) 2.8 mol H2/mol sucrose, hydrogen production rate (HPR) 437 mmol H2/L/d and specific hydrogen production rate (SHPR) 224 mmol H2/g-MLVSS/day was obtained at pH 6.0(I). pH 6.8(I) was the optimal conditions for ethanol concentration of 7,743 mg COD/L, ethanol production yield (EY) of 0.013 mol EtOH/mol sucrose, ethanol production rate (EPR) 11.1 g EtOH/L/d. Nevertheless, ethanol concentration decreased during pH shifted operation. The bacteria community structure analysis results showed Clostridium intestinale and Clostridium pasteurianum were the dominats in these fermentors. The bacteria activity decreased during the pH shift operation. Controling pH from 6.0 to 7.0 is favorable for hydrogen and ethanol production.