木質纖維素特性及菌種組成對厭氧醱酵的影響

Impact of lignocellulosic material characteristics and microbial community composition on anaerobic digestion

柯筱恩(Hsiao-En Ko)

指導教授 ： 柯淳涵

國立臺灣大學/生物資源暨農學院/森林環境暨資源學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202002869

摘要

生質能源(Biomass energy)的是應用生質物 (特別是植物)，從植物中取得的有機碳，將其轉換成可利用的主要能源，如生質氫氣(Bio-hydrogen)與生質甲烷 (Bio-gas)，以替代石油和天然氣。
使用生質能源和石化能源不同的地方在於，以厭氧醱酵甲烷來說，是由太陽行光合作用將碳儲存於植物體中，因此當我們將其利用產生甲烷燃燒，可以視為一個封閉式的碳循環系統，並不會額外製造更多的溫室氣體。台灣日照時間長、氣候溫熱潮溼、地處於熱帶與亞熱帶交界處、高山多地形起伏大，地形種類多，因此利於多樣化的木質纖維作物及微生物生長。養豬場是許多人避之唯恐不及的擾鄰建築，糞尿污染周遭環境，河川、土地。若我們能將這兩者結合，將廢棄木質纖維及豬糞尿結合應用於升值甲烷的開發利用，不只能解決豬糞尿汙染問題，還可以減少石化能源的使用，減少更多二氧化碳的產生。
本研究使用不同的生質物進行厭氧醱酵，及另外添加來自紙廠的厭氧汙泥餅進行厭氧醱酵。總甲烷產氣量而言，已單純使用豬場菌產氣量較好；但就每克使用固形分所產生的甲烷的使用效率來看，可發現大多以添加紙廠菌的結果較好，這可由後續的結晶度、剩餘纖維素含量、次世代定序 (next generation sequencing, NGS) 分析解釋。
由結晶度、剩餘纖維素含量、NGS測定，可以發現單純添加豬場菌的厭氧醱酵系統其分解糖產生有機酸的菌群較多，因此可發現纖維素降解較多且結晶度也下降較多，使得總甲烷產氣量較高。就添加紙廠菌厭氧醱酵系統而言，以嗜乙酸甲烷菌為主要菌群，使得分解木質纖維素菌群較少。因此和未添加紙廠菌相比較可以發現，降解木質纖維素的能力較差，剩餘纖維素含量較高且剩餘結晶度也較高。然而因嗜乙酸甲烷菌較多，一但產生有機酸便可迅速被甲烷菌利用，使得每克使用固形分所產生的甲烷的使用效率較好。

關鍵字

農業廢棄物 ； 厭氧醱酵 ； 生質甲烷 ； 結晶度 ； 次世代定序

並列摘要

Biomass energy is generated from the conversion of organic carbon, obtained from organisms (especially plants) into primary energy sources. The difference between using biomass and petrochemical energy is the carbon source. Carbon dioxide emitted from burning biomass is fixed and stored in plants through photosynthesis. The combustion of bioenergy sources is considered a closed carbon circulation system and does not produce extra greenhouse gases carbon dioxide.
In this study, various substrates were used for anaerobic digestion, some of which involved anaerobic sludge cake from paper plants, and differences were compared. Methane accumulation through anaerobic digestion without added anaerobic sludge cake was found to be favorable. However, in terms of efficiency, the methane yield per gram of volatile solid content (VS) used through anaerobic digestion with anaerobic sludge cake was most favorable. These results were investigated further by assessing the crystallinity and cellulose residue and through next-generation sequencing (NGS).
In NGS analysis, more bacteria could convert sugar into organic acids through anaerobic digestion without added anaerobic sludge cake. Therefore, the cellulose content and crystallinity were degraded, and methane accumulation increased. The dominant bacteria of the anaerobic digestion system with added anaerobic sludge cake were Methanosaeta spp. Consequently, the cellulose degradation potential decreased, the residual cellulose content and crystallinity are all higher, and methane accumulation decreased. However, Methanosaeta spp. are the dominant bacteria to metabolize organic acids upon production. This increases the methane yield per gram of VS used for anaerobic digestion with added anaerobic sludge cake.

並列關鍵字

Agricultural waste ； Anaerobic digestion ； Biomethane ； Crystallinity ； Next-generation sequencing

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