Huang Zhenshan, Tan X Q, Wei Z S, Jiao H Y, Xiao X L, Ming S
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, China.
National Key Laboratory of Water Environmental Simulation and Pollution Control, Ministry of Ecology and Environment of the People's Republic of China, South China Institute of Environmental Sciences, Guangzhou, 510530, China.
Appl Microbiol Biotechnol. 2020 Oct;104(19):8489-8504. doi: 10.1007/s00253-020-10827-1. Epub 2020 Aug 18.
Coupling elemental mercury (Hg) oxidation, autotrophic denitrifying sulfur oxidation, and sulfur disproportionation offers technological potential for simultaneous Hg and nitric oxide (NO) removal. This study shed light on simultaneous demercuration and denitration of flue gas by a sulfur-oxidizing membrane biofilm reactor (MBfR). Removal efficiency of Hg and NO attained 92% and 83%, respectively in long-term operation. Taxonomic and metagenomic study revealed that a tremendous variety of Hg-oxidizing bacteria (MOB) (Thiobacillus, Truepera, etc.), denitrifying/sulfur-oxidizing bacteria (DSOB) (Thioalkalivibrio, Thauera, etc.), sulfur-disproportionating bacteria (SDB) (Desulfobulbus, Desulfomicrobium, etc.), and multi-functional bacteria (Halothiobacillus, Thiobacillus, etc.) significantly increased in abundance during growth under feeding of Hg and NO in simulated flue gas. The comprehensive employment of sequential chemical extraction processes, inductive coupled mass spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy coupled to energy disperse spectroscopy confirmed that Hg was finally biologically oxidized to crystallized metacinnabar (β-HgS) extracellular micromolecular particles. Our findings provided mechanistic insights that MOB, DSOB, and multi-functional bacteria synergistically bio-oxidized Hg as the initial electron donor to Hg and denitrified NO as the terminal electron acceptor to N. SDB disproportionated S branched from SO into S and SO, and β-HgS formation from Hg and disproportionation-derived S, thermodynamically favored Hg bio-oxidation. This novel biotechnique can be a cost-effective and environmentally friendly alternative to flue gas Hg and NO treatment. KEY POINTS: • Combination of Hg bio-oxidation and autotrophic denitrifying sulfur oxidation achieved simultaneous Hg and NO removal. • Thiosulfate disproportionation reinforced Hg bio-oxidation for Hg removal. • Mercury-oxidizing bacteria, denitrifying/sulfur-oxidizing bacteria, and sulfur-disproportionating bacteria synergistically accomplished Hg and NO removal.
耦合元素汞（Hg）氧化、自养反硝化硫氧化和硫歧化反应为同时去除汞和一氧化氮（NO）提供了技术潜力。本研究揭示了硫氧化膜生物膜反应器（MBfR）对烟气进行同步脱汞和脱硝的过程。在长期运行中，汞和NO的去除效率分别达到了92%和83%。分类学和宏基因组学研究表明，在模拟烟气中通入汞和NO的条件下生长时，种类繁多的汞氧化细菌（MOB）（硫杆菌属、特鲁珀菌属等）、反硝化/硫氧化细菌（DSOB）（硫碱弧菌属、陶厄氏菌属等）、硫歧化细菌（SDB）（脱硫球菌属、脱硫微菌属等）和多功能细菌（嗜盐硫杆菌属、硫杆菌属等）的丰度显著增加。通过连续化学萃取过程、电感耦合质谱、X射线衍射、X射线光电子能谱以及扫描电子显微镜与能量色散光谱联用等综合方法证实，汞最终被生物氧化为结晶态的辰砂（β-HgS）细胞外微分子颗粒。我们的研究结果提供了如下机理见解：MOB、DSOB和多功能细菌协同将汞生物氧化，以汞作为初始电子供体，将NO反硝化为N作为终端电子受体。SDB将从SO歧化而来的S歧化为S和SO，汞与歧化产生的S形成β-HgS，从热力学角度有利于汞的生物氧化。这种新型生物技术可以成为一种经济高效且环境友好的烟气汞和NO处理替代方法。要点：• 汞生物氧化与自养反硝化硫氧化相结合实现了汞和NO的同时去除。• 硫代硫酸盐歧化增强了汞生物氧化以去除汞。• 汞氧化细菌、反硝化/硫氧化细菌和硫歧化细菌协同完成汞和NO的去除。
