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.
J Hazard Mater. 2021 Mar 15;406:124310. doi: 10.1016/j.jhazmat.2020.124310. Epub 2020 Oct 17.
Methylmercury (MeHg) is one of the highly toxic and bio-accumulated forms of mercury. Its presence in wastewater treatment processes has been evidenced in recent studies. Considering its enrichment in sewage sludge and the ecological risk associated with its land application, this study investigated the fate of mercury and MeHg in full-scale anaerobic digestion combined with Cambi thermal hydrolysis based on one-year sampling. Results showed that the advanced anaerobic digestion could increase the total mercury (THg) content from 4.35 ± 0.43 mg/kg in raw sludge to 6.37 ± 1.05 mg/kg in digested sludge, and the MeHg content decreased from 1.61 to 8.94 ng/g in raw sludge to 0.21-2.03 ng/g after anaerobic digestion. The demethylation of MeHg was dominant in both thermal hydrolysis and anaerobic digestion; it was mostly derived from the physico-chemical impacts such as chemical decomposition in thermal hydrolysis and precipitation in anaerobic digestion. Although the reported microbial methylators, such as Methanosarcina and Clostridia, were dominant in anaerobic digestion, the relative abundances of hgcA and merA were relatively low and did not correlate with the MeHg profiles. Thus, microbial methylation or demethylation seems negligible in terms of MeHg transformation.
甲基汞（MeHg）是一种毒性高且具有生物累积性的汞形态。最近的研究已经证明其存在于废水处理过程中。考虑到它在污水污泥中的富集以及其土地应用所带来的生态风险，本研究基于为期一年的采样，调查了在全规模厌氧消化与 Cambi 热水解相结合的过程中汞和 MeHg 的归宿。结果表明，先进的厌氧消化可以将总汞（THg）含量从原始污泥中的 4.35±0.43mg/kg 提高到消化污泥中的 6.37±1.05mg/kg，而 MeHg 含量从原始污泥中的 1.61ng/g 降低到厌氧消化后的 0.21-2.03ng/g。MeHg 的脱甲基作用在热水解和厌氧消化中均占主导地位；它主要源于热水解中的化学分解和厌氧消化中的沉淀等理化影响。尽管在厌氧消化中，报道的微生物甲基化菌，如 Methanosarcina 和 Clostridia，占优势，但 hgcA 和 merA 的相对丰度较低，且与 MeHg 谱图无关。因此，就 MeHg 转化而言，微生物甲基化或脱甲基似乎可以忽略不计。
