酒粕生物產氫之研究

Abstract

酒粕為釀酒產業的主要廢棄物，約佔生成副產物之85%，酒粕目前主要做為畜牧業飼料的添加物，但因為富含有機成份，所以也應思考其他方面的應用。氫氣除了具高熱值外，其燃燒後僅會產生水，是一種理想的替代能源，且能經由生物程序降解有機物產生。因此本研究之目的即利用酒粕為原料，找出以其進行生物產氫的最佳操作條件。 本研究所使用的酒粕其成份為：纖維素5.35%、半纖維34.83%、木質素9.01%及灰分2.63%。菌種則取自養牛場的厭氧污泥，經過加熱前處理15分鐘以去除其他耗氫菌，同時保留產氫菌；也進行高溫醱酵測試是否有抑制甲烷生成菌之效果。酒粕亦加入稀鹽酸做前處理，並加熱至沸騰後維持30分鐘，然後將離心後之污泥冷卻後與適量乾燥酒粕置入反應槽，均勻混合，在不同溫度(37℃, 45℃, 50℃, 55℃及60℃)及不同pH (5, 6, 6.5及7)的條件下進行醱酵測試。 實驗結果發現以2%稀鹽酸做前處理之產氫效果比0.365%來得好，最佳產氫條件為pH6及37℃，最大產氫量及氫氣濃度分別達到46 mL H2/g TVS及73.17%。而反應槽添佳營養液除了可以縮短菌種產氫時間，使產氫醱酵作用在24小時內結束外，並能有效降低甲烷的生成量。

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.