School of Resources & Environment, Henan Polytechnic University, Jiaozuo 454000, China.
School of Resources & Environment, Henan Polytechnic University, Jiaozuo 454000, China; School of Environment and Health, Jianghan University, Wuhan 430056, China.
J Environ Sci (China). 2022 Sep;119:130-138. doi: 10.1016/j.jes.2022.06.035. Epub 2022 Jul 4.
Current knowledge about the transformation of total mercury and methylmercury (MeHg) in aerobic composting process is limited. In this study, the composition and transformation of mercury and dissovled organic matter (DOM) in aerobic composting process of municipal sewage sludge were were comprehensively characterized, and the differences among the three C/N ratio (20, 26 and 30) were investigated. The main form of mercury in C/N 20 and 26 was organo-chelated Hg (F3, 46%-60%); while the main form of mercury in C/N 30 was mercuric sulfide (F5, 64%-70%). The main component of DOM in C/N 20 and 26 were tyrosine-like substance (C1, 53%-76%) while the main fractions in C/N 30 were tyrosine-like substance (C1, 28%-37%) and fulvic-like substance (C2, 17%-39%). The mercury and DOM varied significantly during the 9 days composting process. Compared to C/N 20 and 26, C/N 30 produced the less MeHg after aerobic composting process, with values of 658% (C/N 20), 1400% (C/N 26) and 139% (C/N 30) of the initial, respectively. Meanwhile, C/N 30 produced the best compost showed greater degree of DOM molecular condensation and humification. Hg fraction had been altered by DOM, as indicated by a significant correlation between mercury species and DOM components. Notably, C/N 30 should be used as an appropriate C/N ratio to control the methylation processes of mercury and degration of DOM.
目前，关于总汞和甲基汞（MeHg）在好氧堆肥过程中的转化的知识有限。本研究全面考察了城市污水污泥好氧堆肥过程中汞和溶解有机质（DOM）的组成和转化，并研究了三种不同 C/N 比（20、26 和 30）之间的差异。C/N 比为 20 和 26 时，汞的主要形态为有机螯合汞（F3，占 60%64%）；而 C/N 比为 30 时，汞的主要形态为硫化汞（F5，占 70%64%）。C/N 比为 20 和 26 时，DOM 的主要成分是酪氨酸样物质（C1，占 76%53%），而 C/N 比为 30 时，DOM 的主要成分是酪氨酸样物质（C1，占 37%28%）和富里酸样物质（C2，占 39%~17%）。在 9 天的堆肥过程中，汞和 DOM 变化显著。与 C/N 比为 20 和 26 的相比，C/N 比为 30 的好氧堆肥后产生的 MeHg 更少，分别为初始值的 658%（C/N 比为 20）、1400%（C/N 比为 26）和 139%（C/N 比为 30）。同时，C/N 比为 30 的堆肥产物质量最好，DOM 分子的缩合和腐殖化程度更高。Hg 形态受 DOM 影响发生了变化，这表明汞形态与 DOM 成分之间存在显著相关性。值得注意的是，C/N 比为 30 应该作为一个合适的 C/N 比来控制汞的甲基化过程和 DOM 的降解。
