He Xiang-Lin, Liu Ji-Bao, Yin Yong-Guang, Tan Ying-Feng, Zhu Ai-Ling, Zuo Zhuang, Gao Shan, Xie Li-Ping, Wei Yuan-Song
School of Environmental Science and Engineering, Tianjin Polytechnic University, Tianjin 300387, China.
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Huan Jing Ke Xue. 2020 Mar 8;41(3):1425-1431. doi: 10.13227/j.hjkx.201909060.
To study the migration and transformation of methylmercury during advanced anaerobic digestion of sludge and the role of sulfate, this study investigated the migration and transformation of methylmercury during different stages of sludge anaerobic digestion (AD) with thermal hydrolysis pretreatment and under different dosages of sulfate addition. The results showed that mercury methylation occurred in the initial stage of AD (Day 1-3), the ratio of methylmercury to total mercury increased from 0.024% (range of 0.019%-0.033%) to 0.038% (range of 0.030%-0.048%), and the net increment of methylmercury increased by 3.97, 6.09, 0.17, 3.71, and 1.66 times, respectively. In the following Day 3-5, the demethylation process occurred with the net yield of methylmercury decreased by 71.25% (ranging from 67.42% to 75.10%). Sulfate inhibited the methylation of mercury in the initial stage of AD, but had little effect on it in the late stage. This was related to the reduction of the bioavailability of neutral mercury complexes by charged groups of HgHS and HgS, as well as the immobilization of iron sulfide and mercury sulfide on S and bioavailable mercury. Redundancy analysis (RDA) showed that mercury methylation was affected by several factors:organic substances such as propionic acid, isobutyric acid, isovaleric acid, and Fe may promote mercury methylation, whereas protein and higher pH may be inhibitors of mercury methylation in AD of sludge.
为研究污泥深度厌氧消化过程中甲基汞的迁移转化及硫酸盐的作用，本研究考察了热水解预处理污泥厌氧消化（AD）不同阶段以及不同硫酸盐添加量下甲基汞的迁移转化情况。结果表明，AD初期（第1 - 3天）发生汞甲基化，甲基汞占总汞的比例从0.024%（0.019% - 0.033%）增至0.038%（0.030% - 0.048%），甲基汞净增量分别增加3.97、6.09、0.17、3.71和1.66倍。在随后的第3 - 5天，发生去甲基化过程，甲基汞净产量下降71.25%（67.42% - 75.10%）。硫酸盐在AD初期抑制汞甲基化，但后期影响较小。这与HgHS和HgS的带电基团降低中性汞络合物的生物可利用性以及硫化铁和硫化汞对硫和生物可利用汞的固定作用有关。冗余分析（RDA）表明，汞甲基化受多种因素影响：丙酸、异丁酸、异戊酸等有机物以及铁可能促进汞甲基化，而蛋白质和较高的pH值可能是污泥AD中汞甲基化的抑制剂。
