| Summary: | 碩士 === 長庚大學 === 化工與材料工程學系 === 99 === Swelling and disruption of Ca-alginate immobilization carrier by aeration and agitation are inevitable in the co-culture system that cause low production rate. In this study, we improved the carrier materials and develop a suitable gel matrix for the long-term immobilization culture of strains and established the optimal operating conditions for high-efficient ethanol production using a modified bioreactor.
Our results showed that Ba-alginate (10% w/v) carrier had better enzyme activity than Ca-alginate carrier in the flask experiments using Carboxymethylcellulose (CMC). Under the optimal operation conditions of Ba-alginate 4%、aeration rate 1 vvm、agitation rate 150 rpm、2 day pre-culture, our modified co-culture cell bioreactor had ethanol production concentration of 778 ppm/10g-CMC at 8 hr with the theoretical maximum yield of 15.6%. Among the different pretreatment substrates of rice straw, the ethanol concentration was 600 ppm at 7 hr with the theoretical maximum yield of 24% and 1254 ppm at 29 hr with the theoretical maximum yield of 16.7% for 10 g/L and 30 g/L rice straw substrates, respectively. In a repeat-batch culture conditions with the total pretreatment rice straw concentration of 20 g/L, the total ethanol production can reached 1002 ppm at 34 hr, the yield for three batches were about 24%, 12%, 18%, respectively.
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