| Summary: | 碩士 === 大葉大學 === 生物產業科技學系 === 99 === To avoid grain prices rising and causing inflation, production of the biomass fuel alcohol of the second era is mostly abandoned grain crops, and used the non-grain crops of abounded biomass cellulose or agriculture waste as raw materials. The saccharides that biomass fiber through preprocessing hydrolysis and producing are used by organism methods for fermentation to get alcohol, and the saccharides of the kind of raw materials obtained possess the two classes of five carbon and six carbon. In order to amply use these reducing sugars, developing co-fermentation process is an important topic. The bacteria strains that are able to ferment five carbon saccharides are quite rare in the nature world, and therefore using gene recombination to develop new bacteria strains is an important work. Besides the fermentation rate of the five carbon saccharides is quite slow, and therefore the rising of efficiency is also an important research.
This research is according to the earlier established Pichia stipitis fermentation model, and analyzing the efficiency problem of two-tank continuous fermenting glucose and xylose the mixture solution to produce alcohol. The used substrate sources of two-tank continuous fermentation, in accordance with preprocessing, can be classified as 50 g/L pure glucose and the mixture solution of 8 g/L glucose/24 g/L xylose, the two sorts. Therefore, this research is designed that tank-one and tank-two are particular fed one kind of substrates, and the first tank is fed two kinds of substrates at the same time, et cetera, many kinds of operating method, to confer ethanol production rate, ethanol produced ratio, and substrate used ratio, et cetera, the variation under respective sorts of combination, and analyze the ethanol production rate.
When comparing two-tank continuous fermenting and one-tank continuous fermenting, two-tank ethanol production rate is not certainly higher, but substrate used ratio is higher. For example of pure glucose fed, one-tank ethanol production rate in dilution rate 0.06 1/hr is 0.24 g/L/hr, and substrate used ratio is 0.265; and two-tank ethanol production rate, in the first and second dilution rate particularly 0.06 1/hr and 0.30 1/hr, is 0.232 g/L/hr, and substrate used ratio is 0.306. And the case of the first tank fed mixture solution substrates and the second tank fed pure glucose of two-tank continuous fermenting, mixture solution fed dilution rate 0.015 – 0.1 1/hr, and pure glucose fed dilution rate 0.050 1/hr, and dilution rate of liquid flowing from the first tank into the second tank 0.0005 1/hr, equivalent to the volume of the second tank being at least 30 times of the volume of the first tank, can get the most ideal ethanol production rate 0.267 g/L/hr, but neither ethanol produced ratio 0.323 nor substrate used ratio 0.34 are ideal. Because dilution rate is lower, ethanol production rate is lower, but ethanol produced ratio and substrate used ratio are higher. That is ethanol produced ratio and substrate used ratio needing sacrificing in order to obtain the highest ethanol production rate.
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