| Summary: | 碩士 === 國立臺灣大學 === 生物產業機電工程學研究所 === 99 === Spent grain is the main waste in brewery industry, contributing around 85% of total byproducts. It is mainly used as the animal feed additives. However, other applications should be concerned about since it contains abundant organics. Hydrogen has being considered as an ideal alternative energy for its high heating value and it produce only clean water after combustion, and it could be produced through biodegradation of the organic material. The objective of this study is to find out the optimum operational condition for using the spent grain as substrate.
The composition of the spent grain used in this study is: 5.35% cellulose, 34.83% hemi-cellulose, 9.01% lignin and 2.63% ash. The seeding bacteria were obtained from the anaerobic sludge in a dairy farm. Heating pretreatment of 15 minutes for the sludge was conducted to kill those hydrogen utilizing bacteria. Thermophilic fermentation tests were also conducted to tests its effect in inhibiting the methanogen. Dilute acid was added to the spent grain for pretreatment and was heated to boiling for 30 minutes. The pretreated spent grain was then mixed with the centrifuged cold sludge homogeneously and fed into the reactor. Fermentation tests were designed and conducted under conditions of different temperature (37℃, 45℃, 50℃, 55℃ and 60℃) and different pH (5, 6, 6.5 and 7).
Experimental results showed that 2% HCl pretreatment had higher hydrogen production than 0.365% HCl. The maximal hydrogen yield of 46 mL H2/g TVS and the hydrogen content of 73.17% were achieved under the optimal operational condition: pH 6 and 37℃. Addition of nutrient broth could shorten the hydrogen-producing time within 24 hrs and effectively decrease the methane production.
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