Fermentative Production of Biofuels with Entrapped Anaerobic Sludge Using Sequential HRT Shifting Operation in Continuous Cultures

本研究利用碳水化合物當基質、聚乙基辛基彈性體(POE)固定化厭氧污泥為生物觸媒，進行連續醱酵反應以同時産生氣體（氫氣）和液體（乙醇）生物燃料，並利用水力停留時間(HRT)的高低轉換調整來改善氫氣和乙醇生産之效能。實驗結果顯示，以蔗糖為基質，其有機負荷速率增加（即HRT縮短）時，其氫氣與乙醇之産量增多。最佳的生物燃料産量發生於HRT=0.5h時，可得到最高産氫速率為37.4mmlo/h L、最高氫氣産率為1.18mol H2/(mol hexose)、最高乙醇生産速率為84.1mmol/h L、而最高乙醇産率為0.9mol ethanol/(mol hexose)^(-1)。當以葡萄糖為基質來進行HRT轉換培養操作時，其生物燃料之生産有稍微不同的趨勢，其最適乙醇秤操作為HRT=1h時，而最佳産氫操作的HRT為0.5h，且與以蔗糖為基質之實驗相比較，利用葡萄糖為基質時，其生物燃料之産速和産率皆較低。對於所有的連續培養操作，乙醇是最主要的水溶性代謝産物，佔35-78%的液相代謝物産時，相對地，乙酸和丁酸的産量甚少。若以氫氣和乙醇兩個生物燃料來計算其總産能量，以蔗糖為基質，當操作於HRT=0.5h時，可得到最佳能量産速為116kJ/h L和最佳能量産率為1235kJ/(mol hexose)。

關鍵字

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並列摘要

In this work, a continuously stirred tank bioreactor (CSTBR) was used to produce gaseous (hydrogen) and liquid (ethanol) biofuels simultaneously from carbohydrate substrates using immobileized anaerobic sludge with polyethylene-octene-elastomer (POE) matrix. The continuous culture was operated by sequentiall decrease and increase of hydraulic retention time (HRT) to assess the effect of HRT shifting on the efficiency of H2 and ethanol production. The experimental results show that during HRT-decreasing operation, using sucrose as the carbon substrate resulte in increasing H2 and ethanol production with an increase in organic loading rate or a decrease in HRT. The best biofuel-producing performance occurred during HRT decrease, giving the highest H2 production rate and yield of 37.4mmol/h/L and 1.18mol H2/(mol(hexose)), respectively (at 4 h HRT), as well as a maximal ethanol production of 84.1mmol/h/L and 0.9mol ethanol/(mol(hexose)) (at 0.5 h HRT). For continuous cultures fed with glucose-based medium, the biofuel production rate and yield was lower than those from using sucrose, and the dependence of biofuels production on HRT shifting had a slightly different trend. Ethanol production with glucose-feeding cultures seemed to be optimal during a HRT increase (HRT-1h), but H2 production reached maximum during a decreasing HRT (HRT-1h). For all the continuous cultures, ethanol was the predominant soluble metabolite, accounting for 35-78% of total soluble microbial products, while production of acetate and butyrate was less significant. Calculation of total energy generateon resulting from combination of the two biofuels shows that the best energy generation rate (116 kJ/h/L) and yield (1235kJ/(mol(hexose))) was obtained during HRT decreasing (HRT-0.5h) while using sucrose was the carbon substrate.

並列關鍵字

Anaerobic sludge ； Bioethanol ； Biohydrogen ； Continuous culture ； Dark fermentation ； Hydraulic retention time ； Immobilize cell ； Polyethylene-octene-elastomer

國際替代計量

Fermentative Production of Biofuels with Entrapped Anaerobic Sludge Using Sequential HRT Shifting Operation in Continuous Cultures

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