| Summary: | 碩士 === 國立交通大學 === 環境工程系所 === 104 === High demand and apply of fossil fuel has caused not only shortage problem, but also greenhouse effect and climate change. Therefore, the development and application of biomass energy has caught the attention around the world to reduce fossil fuel consumption and energy conservation to be eco-friendly. Beside bio-ethanol and bio-diesel that had industrialized developed, bio-butanol can be prospective biofuels product by Clostridium through ABE fermentation process. This is because bio-butanol has a higher energy density than ethanol, and can be uniformly mixed with gasoline due to their similar octane number. Low water content without modification of vehicle engine is not necessary as well because bio-butanol has low water content. This would be a high prospective biofuel.
Taiwan's has annual output of two million tonnes agricultural wastes, these agricultural waste can become renewable resources through biomass technology so that the reduction greenhouse gas emission can be achieved. Lignocellulosic biomass pretreatment process will produce some degradation byproducts and soluble sugar that can be use as a fermentable sugar for microorganism. Vanillin in compound of hydrolysis byproducts belongs to a type of phenolic compound, which results in significantly inhibited ethanol fermentation, however the ABE fermentation was less been explored. Microorganisms was embedded in PVA- Alginate as immobilized cells to increase cell density, and ABE fermentation was occurred inside the upflow bioreactor operated in continuous condition which can help to reduce the dead time and reduce the inhibition of butanol production. Butanol will be produce by C. saccharoperbutylacetonicum N1-4 through ABE fermentation process in this experiment. Investigation of the influence of batch free cells with and without vanilla on the cell concentration, glucose utilization and changes in solvent will be carry out in this experiment. After that Gompertz equation will be used to analyze the results.
During the free cell experiment, with the medium containing 25 g/L glucose, 2.5 g/L acetic acid and 2 g/L butyric acid, if 0.5 g/L vanillin was added, the complete glucose consumption by microbes will be delayed for four days. The alcohol concentration will be decreased by 33% due to the inhibition of the growth of cell concentration by 20%. Vanillin involved in the reduction reaction can be converted to vanillyl alcohol through ABE fermentation process, this substance can reduce the toxicity to microorganisms and biological conversion rate by 74%, but if the concentration of vanillin unable to load up to microbes may still cause severe suppression. In the immobilized cell experiment, at dilution rate of 0.01 h-1, the glucose utilization rate and cell concentration is the highest, which will provide best condition for butanol production. The continuous operation with dilution rate increased to 0.03 h-1 show the gradually increasing trend of ABE yield and ABE productivity. At dilution rate of 0.03 h-1, the butanol production and yield were highest, which are 0.28 g/g and 0.15 g/L/h respectively while in the batch operation, the butanol production and yield were 0.24 g/g and 0.06 g/L/h. Therefore, by comparison, the butanol productivity and yield of continuous operation is better than batch operation. On the other hand, when two continuous feed media with 0.03 h-1 dilution ratio, both containing 25 g/L glucose, 2.5 g/L of acetic acid with one containing 2 g/L butyric acid and another containing 1 g/L butyric acid, the difference in butanol productivity and yield is negligible, which represents that the up-flow bioreactor is stable and the continuous operation can reduce the dead time.
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