| Summary: | 碩士 === 國立成功大學 === 化學工程學系碩博士班 === 97 === We investigated the impact of gas-stripping on the in situ removal of acetone, butanol, (AB) from batch reactor fermentation broth. The strain, Clostridium beijerinckii, was not affected adversely by gas stripping. A sizable improvement in the productivity and yield was observed in this research in comparison with the non-integrated process. In an integrated process of AB fermentation-recovery using Clostridium beijerinckii, AB productivity and yield were improved up to 50 and 10.8%, respectively, as compared to the controled batch fermentation data. In a batch reactor Clostridium beijerinckii utilized 30.9 g glucose L-1 and produced 11.3 g total AB L-1, while in the integrated process it utilized 38.8 g glucose L-1 and produced total AB of 15.3 g L-1. In the integrated process, acids were totally converted to solvents when compared to the non-integrated process (batch fermentation) which retained residual acids at the end of fermentation. In situ removal of AB by gas stripping has been informed to be one of the most important techniques of solvent removal. During these researches we were capable to maintain the AB concentration in the fermentation broth below toxic levels.
Another study was carried out to study the effect of trace metal addition for butanol production The results show that this bacterial need a selected nutrient with selected concentration. Trace metal addition to the new medium showed that magnesium and calcium enhanced the butanol yield. The results showed that 1.2 g L-1 MgSO4 enhanced the butanol yield from 0.073 g g-1 glucose utilized to 0.115 g g-1 glucose utilized with biomass concentration of 5.35 g L-1. Magnesium and calcium addition were better for growth and for butanol production. Biomass concentration increases as trace metal increases in the fermentation medium. The highest biomass concentration was 5.35 g L-1 at 1.2 g L-1 MgSO4, 5.98 g L-1 at 6 g L-1 MgSO4 and 4.86 g L-1 at 1.1 g L-1 CaCl2, suggested that magnesium and calcium trace metal are necessary for biomass production.
The effect of orange peel concentration on ethanol production by the ethanologenic bacterium Saccharomyces carlsbergensis was investigated. Orange peel was added in various amounts to determine its effects on ethanol production. Fermentation of sugar solutions was conducted at 30 oC. The ethanol produced by Saccharomyces carlsbergensis was determined after 0, 13, 21, 27, 35, 41, and 48 h. At 1, 1.5, 2, 2.5 g per 150 mL orange peel concentration, 0.13, 0.10, 0.09, and 0.08% (v/v) ethanol was achieved respectively, while 0.07% (v/v) was realized at 3 g per 150 ml orange peel concentration. The effect of initial orange peel concentration over the range of 1 to 3 g of dissolved solids per 150 ml greatly decreased the ethanol production from 0.13% (v/v) until 0.07% (v/v).
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