| dc.description.abstract | 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. | en_US |