| 摘要: | 隨著全球對能源需求的增加，開發生質能源已成為當今重要課題，厭氧發酵是利用微生物在無氧環境下將廢棄物轉換為沼氣的技術。在台灣，每年產生超過150萬噸的菇類和20萬噸的廢棄太空包，而這些菇包木屑通常以野外焚燒或堆置方式處理，造成環境汙染。然而，菇包木屑中的纖維素可以進行厭氧發酵，產生沼氣用於工業發電，達到廢棄物轉換為生質能源的循環經濟目的。厭氧發酵中菌落所適合的環境大不相同，因此本研究開發兩階段式反應器，使不同菌落在合適的環境下生長，解決微生物間互相抑制問題，分別為1st-stage 酸化/產氫氣製程，發酵溫度35°C、起始pH5.5，2nd-stage甲烷化/產甲烷製程，發酵溫度50°C，來改善傳統單階段發酵穩定性不足之缺點。
菇包木屑中碳含量較高，但若直接投入厭氧發酵中會造成碳氮比失衡，抑制產酸菌及產甲烷菌的活性，因此本研究透過共消化建立最佳碳氮比，並選用畜牧業廢棄物為氮源(如: 雞糞、尿素及雞羽毛等)來解決系統營養源不足問題，本研究結果顯示選用雞糞作為氮源可獲得最高揮發性脂肪酸(Volatile Fatty Acid ,VFA)濃度25.1g/L及氫氣和甲烷產量分別為151mL及370mL，為三組氮源中產氫產甲烷效率最高。
本研究同時開發乾式厭氧發酵來提高廢棄物處理之含量，乾式厭氧發酵所需反應體積較低，可減少人力及時間成本，缺點為會有過多抑制物的累積，及產甲烷時間滯後和產率降低等問題。本研究透過添加油茶果殼生物碳(Camellia Oleifera Shell Biochar ,COSBC)於厭氧發酵系統中，並且探討油茶果殼生物碳最佳製備參數，如熱裂解溫度及時間以尋求最適化製程，其中發現在1st-stage 酸化/產氫氣製程中以COSBC 700°C,1HR有最高VFA濃度可高達28.8 g/L，氨氮抑制物下降21.2%，累積氫氣產量提高72.2%。最後探討COSBC添加量對第一階段影響，當添加量提高至20%時，VFA濃度提升至31.1 g/L，氨氮抑制物下降33.9%，累積氫氣產量提高106.6%。將條件COSBC 700°C,1HR,1.5g、3.0及4.5g投入2nd-stage中，發現COSBC 4.5g可提高25.1%甲烷產量，氨氮濃度下降44.9%，甲烷含量約佔42-71%。綜合以上厭氧發酵因素，觀察到COSBC的添加可加速酸化/產氫氣階段VFA的產生，在產甲烷化階段加速VFA降解，解決產甲烷滯後問題，提供緩衝能力及鹼度使發酵系統中抑制物降低來提升整體沼氣產量，以解決高固體濃度下所遇問題，提高了兩階段厭氧發酵之效率。
;With the increasing global energy demand, the development of sustainable energy sources has become a crucial task. Anaerobic fermentation, a microbial process that converts waste into biogas in an oxygen-deprived environment, holds promise for addressing this challenge. In Taiwan, large quantities of spent mushroom substrate (SMS) and waste space bags are generated annually, posing environmental pollution issues when disposed of through incineration or landfilling. However, the cellulose-rich SMS can undergo anaerobic digestion to produce biogas for industrial power generation, promoting the conversion of waste into bioenergy within a circular economy framework.
To optimize the fermentation process, a two-stage reactor system was developed to accommodate different microbial communities and alleviate microbial inhibition. The first stage involved acidogenesis and hydrogen production at 35°C and pH 5.5, while the second stage focused on methanogenesis at 50°C. This approach aimed to overcome stability issues observed in traditional single-stage fermentation.The carbon-to-nitrogen ratio imbalance in SMS hampers fermentation by inhibiting acidogenic and methanogenic bacteria. To address this, co-digestion strategies incorporating livestock waste as a nitrogen source (e.g., chicken manure, urea, and chicken feathers) were investigated. Results demonstrated that using chicken manure as a nitrogen source achieved the highest volatile fatty acid (VFA) concentration of 25.1 g/L, along with hydrogen and methane yields of 151 mL and 370 mL, respectively, outperforming other nitrogen sources.
Furthermore, dry anaerobic fermentation was employed to increase waste treatment capacity, reducing labor and time requirements. However, challenges such as inhibitory substance accumulation and reduced methane production were observed. This study addressed these issues by adding Camellia Oleifera Shell Biochar (COSBC) to the anaerobic fermentation system and investigated the optimal preparation parameters for COSBC, such as pyrolysis temperature and time, to optimize the process. It was found that in the first stage of acidification/hydrogen production, COSBC prepared at 700°C for 1 hour achieved the highest VFA concentration of up to 28.8 g/L, a 21.2% decrease in ammonia nitrogen inhibitors, and a 72.2% increase in cumulative hydrogen production. The study also examined the effect of COSBC addition on the first stage. When the addition amount was increased to 20%, the VFA concentration increased to 31.1 g/L, the ammonia nitrogen inhibitors decreased by 33.9%, and the cumulative hydrogen production increased by 106.6%. In the second stage, introducing COSBC at dosages of 1.5 g, 3.0 g, and 4.5 g reveals that COSBC 4.5 g results in a 25.1% increase in methane production, a 44.9% decrease in ammonia nitrogen concentration. In conclusion, the two-stage anaerobic fermentation of SMS, combined with nutrient optimization and the use of COSBC, demonstrated improved biogas production. This approach offers a solution for converting high-solid waste into bioenergy efficiently and sustainably. |
