State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
Water Res. 2022 Jul 15;220:118653. doi: 10.1016/j.watres.2022.118653. Epub 2022 May 24.
The bioconversion of waste activated sludge (WAS) into methane is usually limited by the poor hydrolysis of sludge and/or poor syntrophic methanogenesis during anaerobic digestion (AD). In this study, the underlying mechanism of MOF-808 enhancing hydrolysis and syntrophic methanogenesis during AD process of WAS was investigated. Experimentally, with the effects of MOF-808 (150 mg MOF-808/g Volatile Solid (VS)), the methane production and the proportion of methane in biogas increased by approximately 26.7% and 15.6%, respectively, and the lag phase of methanogenesis decreased by 50.8%, which indicate that MOF-808 enhanced the generation efficiency of methane. The changes in activities of main hydrolytic enzymes with and without MOF-808 (150 mg MOF-808/g VS) during AD process revealed that MOF-808 improved the enzymatic hydrolysis of sludge, and the abiotic hydrolysis of sludge extracellular organic substances by MOF-808 shows that the maximum proportion and the initial increasing rate of low-molecular weight fractions increased by 60% and 583.7%, respectively, indicating that MOF-808 can greatly enhance the hydrolysis degree and rate of sludge via abiotic effect. These demonstrate that MOF-808 enhanced both biological and abiotic hydrolysis of sludge during AD. In addition, changes in the concentrations of acetate kinase and volatile fatty acids (VFAs) with and without MOF-808 (150 mg MOF-808/g VS) during AD process showed that MOF-808 accelerated the bioconversion of VFAs to methane, suggesting MOF-808 has a positive effect on syntrophic metabolism for methanogenesis. Moreover, further analyses of the microbial community structure of sludge samples with and without MOF-808 (150 mg MOF-808/g VS) showed that MOF-808 enriched hydrogen-producing bacteria and mixotrophic methanogens (i.e. Methanosarcina), and changed the methanogenic pathway via accelerating proton transfer between syntrophic anaerobes, especially improving the reduction of CO to methane, and resulting in highly efficient syntrophic methanogenesis. These findings, however, may provide an important reference for enhancing AD efficiency of WAS based on MOF-like materials.
废活性污泥（WAS）的生物转化通常受到污泥水解不良和/或厌氧消化（AD）过程中协同产甲烷作用不良的限制。在这项研究中，研究了 MOF-808 增强 WAS 中 AD 过程中水解和协同产甲烷作用的潜在机制。实验中，通过添加 MOF-808（150 mg MOF-808/g 挥发性固体（VS）），甲烷产量和沼气中甲烷的比例分别提高了约 26.7%和 15.6%，产甲烷的迟滞期缩短了 50.8%，这表明 MOF-808 提高了甲烷的生成效率。添加和不添加 MOF-808（150 mg MOF-808/g VS）时 AD 过程中主要水解酶活性的变化表明，MOF-808 改善了污泥的酶解，并且 MOF-808 对污泥细胞外有机物的非生物水解表明，低分子量分数的最大比例和初始增加率分别增加了 60%和 583.7%，表明 MOF-808 可以通过非生物作用极大地增强污泥的水解程度和速率。这些表明 MOF-808 在 AD 过程中增强了污泥的生物和非生物水解。此外，添加和不添加 MOF-808（150 mg MOF-808/g VS）时 AD 过程中乙酸激酶和挥发性脂肪酸（VFAs）浓度的变化表明，MOF-808 加速了 VFAs 向甲烷的生物转化，表明 MOF-808 对产甲烷的协同代谢有积极作用。此外，进一步分析添加和不添加 MOF-808（150 mg MOF-808/g VS）的污泥样品中的微生物群落结构表明，MOF-808 富集了产氢细菌和混合营养型产甲烷菌（即 Methanosarcina），并通过加速协同厌氧菌之间的质子转移改变了产甲烷途径，特别是提高了 CO 向甲烷的还原，从而实现了高效的协同产甲烷作用。然而，这些发现可能为基于 MOF 类似物材料提高 WAS 的 AD 效率提供重要参考。
