高固形物豬糞厭氧消化與共消化之探討

Abstract

以厭氧消化將生質物轉換成替代能源 – 甲烷，在過去己有很好的發展，而高溫厭氧消化也已證實能有效地提高產氣量並且可以操作在更高的有機負荷率。此外，為了產製更多的甲烷，將含碳量較高的生質廢棄物和含氮量較高的畜糞進行共消化，也成為目前研究的重點。 本研究包含單一料源及共消化兩個實驗，第一個實驗是以總固形物濃度5%的豬糞為進流，探討在不同的水力停留時間(HRT 15、10、5天)和不同溫度(55C和37C)下，出流水質(總固形物、揮發性固形物和化學需氧量)和甲烷產率的變化(試驗1 ~ 6)。第二個實驗則以總固形物濃度同為8%的豬糞和葉菜廢棄物混合進流進行共消化，HRT及溫度分別固定在5天和55C，探討在不同的豬糞與葉菜廢棄物混和比(豬糞:葉菜廢棄物為1:0、1:3、1:2、1:1、0:1)其出流水質和甲烷產率的變化(試驗7 ~ 12)。 結果顯示實驗一豬糞厭氧消化在試驗T3，HRT 5天、溫度55C時，有最佳的氣體產率和甲烷產率，分別為2.33 L/L/d及1.34 L CH4/L/d，甲烷含量則為57.36%。 實驗二豬糞與葉菜廢棄物高溫厭氧共消化的結果，有摻合葉菜廢棄物的試驗中，以試驗T9，豬糞與葉菜廢棄物混合比為3:1時，有最佳的氣體產率、甲烷產率和甲烷含量，分別為1.89 L/L/d、1.07 L CH4/L/d及56.64%，TS、VS、COD的去除率皆在30%以上。 以上的實驗結果證實以高固形物含量的豬糞為單一料源，以及與葉菜廢棄物進行高溫厭氧共消化都具可行性並可達到極佳的產氣效果。

The anaerobic digestion, to convert the biomass into the alternative energy – methane, has been well developed for several decades. Also, the thermophilic anaerobic digestion has been proved to increase the gas production effectively and could be operated under a higher organic loading rate than mesophilic process. Besides, the co-digestion of biomass wastes with high carbon content and the livestock manure with high nitrogen content has become an important research field for producing more methane in recent years. There are two parts of experiment: 1. single substrate, and 2. co-digestion, in this study. The first experiment using 5% total solids (TS) swine manure as substrate, tests of different hydraulic retention times (HRT 15, 10 and 5 days) and different temperature (55C and 37C) were conducted to investigate the variations of effluent quality (including TS, volatile solids – TS and chemical oxygen demand – COD) and methane production (test 1~6). The second experiment using both 8% TS swine manure (SM) and vegetable wastes (VW) as substrates for co-digestion, with controlled HRT of 5 days and temperature at 55C, tests of different mixture ratios (1:0, 1:3, 1:2, 1:1 and 0:1 for SM : VW) were conducted to evaluate the variations of effluent quality and methane production (test 7~12). Experimental results showed, in the first experiment of single substrate - swine manure, the optimal gas production rate of 2.33 L/L/d, methane production rate of 1.34 L CH4/L/d and methane content of 57.36% were achieved in test T3 (HRT 5 days and 55C ). For the second experiment of thermophilic anaerobic co-digestion, within the tests mixed with the vegetable wastes, the optimal gas production rate of 1.89 L/L/d, methane production rate of 1.07 L CH4/L/d and methane content of 56.64% were achieved in test T9 (SM : VM is 3:1). It was also observed that all the TS, VS and COD removal efficiencies were higher than 30%. The above experimental results, both using high solids content of swine manure as the single substrate, and mixing with vegetable wastes for thermophilic co-digetion, have successfully proved to be feasible and very effective in gas production.