School of Environment and Society, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.
School of Environment and Society, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.
Sci Total Environ. 2022 Jan 1;802:149961. doi: 10.1016/j.scitotenv.2021.149961. Epub 2021 Aug 26.
Recent attempts have been made to develop a thermophilic composting process for organic sludge to not only produce organic fertilizers and soil conditioners, but to also utilize the generated ammonia gas to produce high value-added algae. The hydrolysis of organic nitrogen in sludge is a bottleneck in ammonia conversion, and its improvement is a major challenge. The present study aimed to elucidate the effects of inoculated Neurospora sp. on organic matter decomposition and ammonia conversion during thermophilic composting of two organic sludge types: anaerobic digestion sludge and shrimp pond sludge. A laboratory-scale sludge composting experiment was conducted with a 6-day pretreatment period at 30 °C with Neurospora sp., followed by a 10-day thermophilic composting period at 50 °C by inoculating the bacterial community. The final organic matter decomposition was significantly higher in the sludge pretreated with Neurospora sp. than in the untreated sludge. Correspondingly, the amount of non-dissolved nitrogen was also markedly reduced by pretreatment, and the ammonia conversion rate was notably improved. Five enzymes exhibiting high activity only during the pretreatment period were identified, while no or low activity was observed during the subsequent thermophilic composting period, suggesting the involvement of these enzymes in the degradation of hardly degradable fractions, such as bacterial cells. The bacterial community analysis and its function prediction suggested the contribution of Bacillaceae in the degradation of easily degradable organic matter, but the entire bacterial community was highly incapable in degrading the hardly degradable fraction. To conclude, this study is the first to demonstrate that Neurospora sp. decomposes those organic nitrogen fractions that require a long time to be decomposed by the bacterial community during thermophilic composting.
最近有人试图开发一种嗜热堆肥工艺来处理有机污泥，不仅可以生产有机肥和土壤改良剂，还可以利用产生的氨气来生产高附加值的藻类。污泥中有机氮的水解是氨转化的瓶颈，如何提高其转化率是一个主要挑战。本研究旨在阐明接种曲霉菌对两种有机污泥（厌氧消化污泥和虾塘污泥）在嗜热堆肥过程中有机质分解和氨转化的影响。采用实验室规模的污泥堆肥实验，在 30°C 下用曲霉菌进行 6 天的预处理，然后在 50°C 下接种细菌群落进行 10 天的嗜热堆肥。用曲霉菌预处理的污泥的最终有机质分解率明显高于未处理的污泥。相应地，预处理也显著降低了非溶解氮的含量，并显著提高了氨转化率。鉴定出 5 种仅在预处理期间表现出高活性的酶，而在随后的嗜热堆肥期间则没有或活性很低，这表明这些酶参与了难以降解部分（如细菌细胞）的降解。细菌群落分析及其功能预测表明芽孢杆菌科在易降解有机物质的降解中起作用，但整个细菌群落对难降解部分的降解能力很差。总之，本研究首次证明，曲霉菌可以分解细菌群落在嗜热堆肥过程中需要很长时间才能分解的那些有机氮部分。
