School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou, 510275, China.
School of Environmental Science and Engineering, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou, 510275, China.
Chemosphere. 2020 Apr;244:125544. doi: 10.1016/j.chemosphere.2019.125544. Epub 2019 Dec 6.
Bacterial mercury oxidation coupled to denitrification offers great potential for simultaneous removal of elemental mercury (Hg) and nitric oxide (NO) in a denitrifying membrane biofilm reactor (MBfR). Four potentially contributory mechanisms tested separately, namely, membrane gas separation, medium absorption, biosorption and biotransformation, which contributed 4.9%/7.2%, 8.1%/8.9%, 38.8%/9.5% and 48.2%/84.9% of overall Hg/NO removal in MBfR. Herein, Hg bio-oxidation, oxidative Hg biosorption and denitrification played leading roles in simultaneous removal of Hg and NO. Living microbes performed simultaneous Hg bio-oxidation and denitrification, in which Hg as electron donor was biologically oxidized to oxidized mercury (Hg), while NO as the terminal electron acceptor was denitrified to N. The Hg further complexed with humic acids in extracellular polymeric substances via functional groups (-SH, -OH, -NH and -COO) and formed humic acids bound mercury (HA-Hg). Non-living microbial matrix performed oxidative Hg biosorption, in which Hg may be physically adsorbed by cellular matrix, then non-metabolically oxidized to Hg via oxidative complexation with -SH in humic acids and finally cleavage of S-H bond and surface charge transfer led to formation of HA-Hg. Therefore, bioconversion of Hg to HA-Hg by Hg bio-oxidation and oxidative Hg biosorption coupled with NO denitrification to N dynamically cooperated to accomplish simultaneous removal of Hg and NO in MBfR.
细菌汞氧化与反硝化偶联在脱氮膜生物膜反应器（MBfR）中具有同时去除元素汞（Hg）和一氧化氮（NO）的巨大潜力。分别测试了四种可能的贡献机制，即膜气体分离、介质吸收、生物吸附和生物转化，它们分别为 MBfR 中总 Hg/NO 去除的 4.9%/7.2%、8.1%/8.9%、38.8%/9.5%和 48.2%/84.9%。在此，Hg 的生物氧化、氧化 Hg 的生物吸附和反硝化在同时去除 Hg 和 NO 方面发挥了主导作用。活微生物同时进行 Hg 的生物氧化和反硝化，其中 Hg 作为电子供体被生物氧化为氧化汞（Hg），而 NO 作为末端电子受体被反硝化为 N。Hg 进一步通过功能基团（-SH、-OH、-NH 和 -COO）与细胞外聚合物中的腐殖酸结合，形成腐殖酸结合汞（HA-Hg）。非活体微生物基质进行氧化 Hg 的生物吸附，其中 Hg 可能被细胞基质物理吸附，然后通过与腐殖酸中的 -SH 发生氧化络合，非代谢地氧化为 Hg，最后 S-H 键断裂和表面电荷转移导致形成 HA-Hg。因此，Hg 的生物氧化和氧化 Hg 的生物吸附将 Hg 转化为 HA-Hg，与 NO 反硝化生成 N 协同作用，在 MBfR 中实现 Hg 和 NO 的同时去除。
