畜殖廢水厭氧共消化提升沼氣產量之模場研究

Abstract

本研究模擬養猪場條件來建立厭氧消化反應器(十萬分之一比例)，分別添加生質柴油副產物粗甘油及微藻殘渣共消化，並且進行厭氧汙泥的循環回流試程，達到改善沼氣生成以及減碳再利用的雙重效益。批次搖瓶試驗得到粗甘油與藻渣最佳添加量分別為0.8 g/L和0.1 g/L。以實驗室規模厭氧消化反應器進行20天連續流試驗，有機廢水添加粗甘油共消化在水停留時間(HRT)8天條件下，沼氣產量增加39% 最為顯著。由水質檢測結果說明，添加粗甘油增加廢水中的有機碳源(TOC)，並使化學需氧量(COD)去除效率提高，藉此提升沼氣產量。在四槽串聯的厭氧汙泥的回流試程中，在汙泥每天回流3%(v/v)條件下，總沼氣產量提升46.4%為最佳，反應器中汙泥含量的多寡直接影響了厭氧消化時之COD去除率。沼氣成分分析中，汙泥回流增加了甲烷的濃度，而添加有機物共消化對於沼氣組成分無明顯影響。利用變性梯度凝膠電泳(DGGE)分析厭氧汙泥菌相結果，古生甲烷菌族群為Methanosaeta與Methanosarcinales，在細菌族群中主要酸化菌群為Clostridium與Smithella，當添加有機物共消化後硫還原菌Deltaproteobacteria的族群下降，在實驗室最佳產氣條件下，反應器中出現了酸化菌群Syntrophus。未來可應用本研究之最佳產氣條件於實場，再利用有機廢棄物以提升沼氣產量，達到更有效率產生潔淨能源之目的。

In this study, we established an effective anaerobic digestion process, which elevate biogas production by treat swine wastewater. The anaerobic digestion experiments were conducted on flask (500ml) in batch cultures and lab-scale anaerobic digester (20L) in continuous conditions. In flask experiments, swine waste was treated with crude glycerol or microalgae residues under pH 8 and 35℃. The results showed that addition of crude glycerol 0.8g/L (0.08%) and microalgae residues 0.1g/L (0.01%) were the greatest biogas production. In lab-scale anaerobic digester experiments, hydraulic retention times (HRT) were adjusted to 6、8、12 days. Results showed that co-digestion with crude glycerol 0.08% increased 39% biogas production at HRT 8 days and the co-digestion with microalgae residues 0.01% increase 14% biogas production at HRT 6 and 8 days. Methane (CH4) was found feasible up to 68% of biogas composition. When sludge return rate were adjusted to 1%、3%、5% per day in series reactor experiments, the results showed that 3% sludge return could obtain the greatest biogas production and stable TCOD removal efficiency. This investigation provides optimal operation parameters for anaerobic digestion, and it could application in full-scale reactor in agriculture field for biogas production.