State Key Joint Laboratory of Environmental Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Bioresour Technol. 2022 Mar;347:126394. doi: 10.1016/j.biortech.2021.126394. Epub 2021 Nov 22.
Reducing health risk of mercury (Hg)/methylmercury (MeHg) in sewage sludge is vital to its land application. This study revealed that thermal hydrolysis reduced MeHg content both during pretreatment process and subsequent anaerobic digestion (AD), which resulted in decrease of MeHg content from 4.24 ng/g to 0.95 ng/g after thermal hydrolysis (150 ℃) and further decreased to 0.39 ng/g after AD. Notably, thermal hydrolysis at high temperature (120 ℃ and 150 ℃) promoted both Hg methylation and MeHg demethylation rather than the control or at low temperature (100 ℃). Hg methylation dominated in hydrolysis and acidogenesis stage, whereas MeHg demethylation dominated in methanogenesis stage. Though abundance of related genes (HgcA and merA) was dramatically reduced, Ruminococcaceae, Peptococcaceae, and Lachnospiraceae were potentially Hg methylators in hydrolysis and acidogenesis stage. Whereas, MeHg demethylation dominated in the late period of AD due to the improved syntrophic methanogenesis and possibly reduced Hg biodegradability by precipitation.
减少污水污泥中汞（Hg）/甲基汞（MeHg）的健康风险对于其土地应用至关重要。本研究表明，热水解在预处理过程中和随后的厌氧消化（AD）中均降低了 MeHg 的含量，导致热水解（150°C）后 MeHg 含量从 4.24ng/g 降低至 0.95ng/g，随后进一步降低至 0.39ng/g。值得注意的是，高温（120°C 和 150°C）下的热水解促进了 Hg 甲基化和 MeHg 脱甲基化，而不是对照或低温（100°C）下的热水解。Hg 甲基化在水解和产酸阶段占主导地位，而 MeHg 脱甲基化在产甲烷阶段占主导地位。尽管相关基因（HgcA 和 merA）的丰度显著降低，但水解和产酸阶段的 Ruminococcaceae、Peptococcaceae 和 Lachnospiraceae 可能是 Hg 甲基化菌。然而，由于共生产甲烷作用的改善和可能由于沉淀而降低了 Hg 的生物降解性，MeHg 脱甲基化在 AD 的后期占主导地位。
