Shaanxi Key Laboratory of Environmental Engineering, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China.
College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China.
Sci Total Environ. 2023 Oct 20;896:165170. doi: 10.1016/j.scitotenv.2023.165170. Epub 2023 Jun 26.
Methane is one of the most promising renewable energies to alleviate energy crisis or replace fossil fuels, which can be recovered from anaerobic digestion of bio-wastes. However, the engineering application of anaerobic digestion is always hindered by low methane yield and production rate. This study revealed the roles and mechanisms of a green-prepared magnetic biochar (MBC) in promoting methane production performance from waste activated sludge. Results showed that the methane yield reached 208.7 mL/g volatile suspended solids with MBC additive dosage of 1 g/L, increasing by 22.1 % compared to that in control. Mechanism analysis demonstrated that MBC could promote hydrolysis, acidification, and methanogenesis stages. This was because the properties of biochar were upgraded by loading nano-magnetite, such as specific surface area, surface active sites, and surface functional groups, which made MBC have greater potential to mediate electron transfer. Correspondingly, the activity of α-glucosidase and protease respectively increased by 41.7 % and 50.0 %, and then the hydrolysis performances of polysaccharides and proteins were improved. Also, MBC improved the secretion of electroactive substances like humic substances and cytochrome C, which could promote extracellular electron transfer. Furthermore, Clostridium and Methanosarcina, as well-known electroactive microbes, were selectively enriched. The direct interspecies electron transfer between them was established via MBC. This study provided some scientific evidences to comprehensively understand the roles of MBC in anaerobic digestion, with important implications for achieving resource recovery and sludge stabilization.
甲烷是一种很有前途的可再生能源，可以缓解能源危机或替代化石燃料，它可以从生物废物的厌氧消化中回收。然而，厌氧消化的工程应用总是受到甲烷产量和产率低的阻碍。本研究揭示了一种绿色制备的磁性生物炭（MBC）在促进废活性污泥产甲烷性能方面的作用和机制。结果表明，当 MBC 添加剂用量为 1 g/L 时，甲烷产量达到 208.7 mL/g 挥发性悬浮固体，比对照提高了 22.1%。机理分析表明，MBC 可以促进水解、酸化和产甲烷阶段。这是因为纳米磁铁矿的负载改善了生物炭的性能，如比表面积、表面活性位和表面官能团，这使得 MBC 具有更大的潜力来介导电子转移。相应地，α-葡萄糖苷酶和蛋白酶的活性分别提高了 41.7%和 50.0%，从而改善了多糖和蛋白质的水解性能。此外，MBC 还提高了腐殖质和细胞色素 C 等电活性物质的分泌，从而促进了细胞外电子转移。此外，梭菌属和产甲烷菌属作为已知的电活性微生物被选择性富集。它们之间通过 MBC 建立了直接的种间电子转移。本研究为全面了解 MBC 在厌氧消化中的作用提供了一些科学证据，对实现资源回收和污泥稳定具有重要意义。
