豬糞尿廢水產氫之研究

Abstract

本研究利用厭氧醱酵技術，以人工廢水和豬糞尿廢水進行產氫測試，醱酵之菌種來自養豬場之厭氧汙泥，厭氧汙泥則採用熱前處理法去除耗氫菌。實驗分成三部分進行探討，第一部分為厭氧汙泥醱酵產氫特性測試，為了解產氫菌在醱酵期間的代謝與生長特性，利用人工廢水為基質分別做兩組試驗，第一組試驗為測試不同有機負荷率對產氫的影響，分別以有機負荷率4、6、8、10、12、16、20 g COD/L/d進行醱酵測試；第二組試驗為探討養豬場厭氧汙泥產氫活性隨時間之動態變化，在兩種不同的有機負荷率4與8 g COD/L/d情況下，每2小時監測一次產氣的狀態。第二部分為實際廢水醱酵產氫測試，為了解厭氧汙泥對實際豬糞尿廢水進行醱酵的效果，設計二組不同的實驗項目，第一組試驗為使用實際的豬糞尿原廢水為基質，有機負荷為2.5 g COD/L進行醱酵，第二組試驗為使用豬糞尿廢水依不同比例混合人工廢水(0%、25%、50%、75%)作複合式醱酵測試。第三部分為半連續式醱酵產氫測試，以1.5 L經前處理過的汙泥與2.5 L濃度為4 g COD/L之人工廢水進行半連續式醱酵，水力停留時間為24小時，反應槽溫度控制在50±1oC，共操作102小時。 實驗結果顯示，在第一部分厭氧汙泥醱酵產氫特性測試中，人工廢水有機負荷率為12 g COD/L/d時有最大的氫氣含量百分比41.2%，以及最大的氫氣產能134 mL H2/g VSadd，同時有機負荷率在8 g COD/L/d以上時，氫氣含量百分比皆可達30%以上。在厭氧汙泥產氫活性動態試驗中，可以發現0~6小時為產氫菌生長之延滯期，氫氣產生則集中於8~16小時。在第二部分實際廢水醱酵產氫測試中，氫氣含量百分比最大為9.9%，氫氣產能為4 mL H2/g VSadd，為相同有機負荷率濃度下，使用人工廢水之氫氣產能的42.1%。在複合式醱酵試驗中，當豬糞尿廢水與人工廢水在相同COD濃度下混合比例為25%時，產氫效果最佳，約為完全使用人工廢水的1.5倍，此時的氫氣產能為48 mL H2/g VSadd。在第三部分半連續式醱酵產氫測試中，反應前30小時產生的氫氣量占了最終氫氣累積量的一半，氫氣含量百分比介於9.2~23.5%，氫氣生成速率最高可達21 mL/hr，反應最終之氫氣產能為18 mL H2/g VSadd。

In this study, experiments of biohydrogen production through anaerobic fermentation with swine wastewater and synthetic wastewater as substrate, were conducted using heat-pretreated digested sludge as seeding bacteria under mesophilic conditions. The experiments in this study could be divided into three parts. First, to examine the metabolism and growth activity of seeding sludge, the synthetic wastewater was used as substrate and had two sets of test: different organic loading rate (4, 6, 8, 10, 12, 16, 20 g COD/L/d) fermentation test, and the dynamic change of the hydrogen production test for every two hours under organic loading rates of 4 and 8 g COD/L/d. Second, to evaluate the effect of using real swine wastewater, two tests were conducted: real swine wastewater as the single substrate, and co-fermentation with swine wastewater and synthetic wastewater. Third, hydrogen production was operated semi-continuously, 2.5 L synthetic wastewater (2.5 g COD/L) was used as substrate and mixed with 1.5 L seeding sludge. The HRT was operated at 24 hours and the experiment duration time was 102 hours. The experimental results showed that, in different organic loading rate fermentation test, the maximum accumulated hydrogen yield of 134 mL H2/g VSadd and a maximum hydrogen content of 41.2% were obtained at the organic loading rate of 12 g COD/L/d when using synthetic wastewater. In the dynamic change of hydrogen production test, the beginning 0~6 hours was observed as lag phase, and the hydrogen produced mostly during 6~16 hours. In real swine wastewater fermentation test of the second part, the maximum hydrogen content of 9.9% with the accumulated hydrogen yield of 4 mL H2/g VSadd were obtained when using swine wastewater as the single substrate, the hydrogen yield was about 42.1% of that using the synthetic wastewater at the same concentration. In co-fermentation test, the optimal hydrogen production was found at a mixing ratio of 1:3 (swine wastewater to synthetic wastewater). The hydrogen yield of 48 mL H2/g VSadd was about 1.5 times that of using only synthetic wastewater. In semi-continuous operation test of the third part, about half of the cumulated hydrogen produced was found in beginning 30 hours. The hydrogen content observed was between 9.2% and 23.5%, and a maximum hydrogen production rate of 21 mL/hr was achieved. At the end of experiment, the observed hydrogen yield was 18 mL H2/g VSadd.