The Effects of Dissolved Oxygen and Different Immobilization Carriers for Ethanol Production from Carboxymethylcellulose using a Novel Co-Culture-Cell Bioreactor

• Main Authors: Chih Han Chou, 周志翰
• Other Authors: Y.K.Liu
• Format: Others
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/90469086854016578085

碩士 === 長庚大學 === 生化與生醫工程研究所 === 98 === There were more than 1600 thousand tons of rice straw agricultural wastes produced in Taiwan every year. Produce bioethanol from rice straw not only regenerates the agriculture waste into bioenergy, but also solves the problem of environmental pollution by rice straw burning. Cellulose is the main component of rice straw. However, it is difficult to hydrolyze the lignocellulose to glucose by enzymes, bio-ethanol produced by lignocellulose still expensive when compared to sugar or starch substrate. Using the technology of cell immobilization might lower the cost by repeat immobilized cells utilization; process of cellulose hydrolysis and glucose fermentation combination, and co-culture system. In this study, we investigated the bio-ethanol production of our new co-culturing immobilized cells system reactor with dissolved oxygen monitored by different immobilization carriers in different aeration or the agitation speed condition. We also study the aerobic/anaerobic zone construction in ethanol production. In the shaking flask research, the enzyme activities of immobilized cells on different carriers showed that loofah sponge performs well in both one stage and two stage immobilize strategy, but decomposed. The loofah sponge decomposed slower when culturing in the bioreactor Besides, suspended culturing in the shaking flask, 2 days preculture could reach highest value summarized enzyme activity in both carboxymethylcellulose and rice straw substrate. We also found the aerobic/anaerobic zones constructed well under the aeration rate of 2L / min. The loofah sponge immobilization carriers, had yield of ethanol concentration reached 825 ppm after 8 hrs fermentation. The aeration rate of 2 L /min performed better than the others. The dissolved oxygen (DO) was affected by different agitation speeds, the DO value rose with the agitation speed. The agitation speed of 150 rpm could maintain the DO level stably with the ethanol concentration reached 934 ppm after 8hrs fermentation. Higher substrate concentration 20g/L of caboxymethylcellulose(CMC) could achieve the ethanol concentration of 1080 ppm after 8 hrs fermentation. Three repeated batches of substrate concentration 10 g/L CMC could reach the ethanol concentration of 2650 after 9 hrs fermentation. These results showed that our immobilized co-culture-cell bioreactor system had high potential of continuous and stable bio-ethanol production.