| 摘要: | 在當今世界人口不斷增長、資源逐漸匱乏的情況下，「循環利用」的概念日益重要，這也解釋了生質能源在再生能源中的獨特地位。厭氧發酵技術利用微生物在無氧環境下將廢棄物轉化為沼氣，這在資源循環中尤為關鍵。台灣每年消費超過十萬噸的菇類，產值約百億元，相應地，每年約有50萬噸的菇包木屑需要處理，常見處理方式如野外焚燒或堆置，不僅不利於環境保護，還造成污染。然而，菇包木屑含有大量纖維素，適合投入厭氧發酵系統轉化為生質能源氫氣和甲烷，實現廢棄物的有效利用，推動循環經濟。
本實驗旨在開發乾式厭氧發酵技術，以提高廢棄物處理的含量。乾式厭氧發酵具有高有機負荷能力和低反應體積需求，這意味著可以節省人力和時間成本。然而，由於流動性較低，乾式發酵質傳效果不佳，導致其生物反應速率低於濕式厭氧發酵。因此，本實驗提出在厭氧發酵系統中添加奈米零價鐵（nZVI），奈米零價鐵在系統中能促進VFA的生成，且提高氫氣和沼氣的總產量。而添加0.6克奈米零價鐵的系統有最佳的效果，沼氣產量為494 mL，其中甲烷產量為410.2 mL，比沒有添加奈米零價鐵的對照組(303.4 mL)高出106.8 mL，增幅達到35.2%。
由於系統中的酸鹼值在發酵後期會高於8，有大幅降低產甲烷菌的活性，因此會在發酵過程加入緩衝溶液，以穩定系統的pH值，保護和促進微生物的活性。未添加緩衝溶液的系統pH值急速上升至8.05，，而在加入緩衝溶液後，相較於對照組，系統的pH值均有下降的趨勢，且隨著緩衝溶液濃度的增加，pH值下降幅度更大。而濃度0.1M的緩衝溶液的酸鹼值降低至7.81，並且擁有最高產氣量為30毫升，其產氣量比對照組高出36毫升，增幅為7.3%，這表明緩衝溶液有效地穩定了系統的pH值，為甲烷菌提供了更適宜的生長環境，從而有助於提高甲烷產量。
;As the world′s population continues to grow and resources become increasingly scarce, the concept of "recycling" becomes increasingly important, which explains the unique position of biomass energy among renewable sources. Anaerobic fermentation technology uses microorganisms to convert waste into biogas in an oxygen-free environment, which is particularly critical in resource recycling. Taiwan consumes more than 100,000 tons of mushrooms annually, with an output value of about 10 billion yuan. Consequently, about 500,000 tons of spent mushroom substrate need processing each year. Common methods such as burning or stacking in the wild harm the environment. However, spent mushroom substrate contains a large amount of cellulose and is suitable for anaerobic fermentation, converting it into hydrogen and methane, thereby achieving effective waste utilization and promoting a circular economy.
This experiment aims to develop dry anaerobic fermentation technology to improve waste treatment content. Dry anaerobic fermentation has a high organic loading capacity and low reaction volume requirements, saving labor and time costs. However, due to low fluidity, dry fermentation has poor mass transfer, resulting in a lower biological reaction rate than wet anaerobic fermentation. Therefore, this experiment proposes adding nanoscale zero-valent iron (nZVI) to the anaerobic fermentation system. Nanoscale zero-valent iron can promote the production of VFA and increase the total production of hydrogen and biogas. The system adding 0.6 grams of nZVI shows the best effect, with biogas production of 494 mL, including 410.2 mL of methane. This is 106.8 mL higher than the control group (303.4 mL) without nZVI, an increase of 35.2%.
Since the pH value in the system will be higher than 8 in the later stage of fermentation, greatly reducing the activity of methanogenic bacteria, buffer will be added during the fermentation process to stabilize the pH value and protect and promote the activity of microorganisms. In the system without buffer, the pH value increased rapidly to 8.05. After adding buffer, the pH value showed a downward trend compared to the control group. As the concentration of buffer solution increased, the pH value decreased further. The pH value of the buffer solution with a concentration of 0.1M was reduced to 7.81 and had the highest biogas production of 30 mL, which was 7.3% higher than the control group, showing that the buffer effectively stabilized the system′s pH value and provided a more suitable growth environment for methanogens, thereby helping to increase methane production. |
