Abstract

Coupling elemental mercury (Hg⁰) oxidation, autotrophic denitrifying sulfur oxidation, and sulfur disproportionation offers technological potential for simultaneous Hg⁰ 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 Hg⁰ and NO attained 92% and 83%, respectively in long-term operation. Taxonomic and metagenomic study revealed that a tremendous variety of Hg⁰-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 Hg⁰ 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 Hg⁰ 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 Hg⁰ as the initial electron donor to Hg²⁺ and denitrified NO as the terminal electron acceptor to N₂. SDB disproportionated S⁰ branched from S₂O₃²⁻ into S²⁻ and SO₄²⁻, and β-HgS formation from Hg²⁺ and disproportionation-derived S²⁻, thermodynamically favored Hg⁰ bio-oxidation. This novel biotechnique can be a cost-effective and environmentally friendly alternative to flue gas Hg⁰ and NO treatment.

Key points

• Combination of Hg⁰ bio-oxidation and autotrophic denitrifying sulfur oxidation achieved simultaneous Hg⁰ and NO removal.

• Thiosulfate disproportionation reinforced Hg⁰ bio-oxidation for Hg⁰ removal.

• Mercury-oxidizing bacteria, denitrifying/sulfur-oxidizing bacteria, and sulfur-disproportionating bacteria synergistically accomplished Hg⁰ and NO removal.

中文翻译：

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汞氧化与自养反硝化分支硫氧化和硫歧化反应同时去除Hg0和NO。

摘要

元素汞（Hg ⁰）氧化，自养反硝化硫氧化和硫歧化的耦合为同时去除Hg ⁰和一氧化氮（NO）提供了技术潜力。这项研究揭示了通过硫氧化膜生物膜反应器（MBfR）同时烟气脱汞和脱硝的方法。在长期运行中，Hg ⁰和NO的去除效率分别达到92％和83％。分类学和宏基因组学研究表明，Hg ⁰氧化细菌（MOB）（硫杆菌，Truepera等），反硝化/硫氧化细菌（DSOB）（硫代碱解弧菌，Thauera）种类繁多等），硫菌歧化（SDB）（Desulfobulbus，Desulfomicrobium等），和多官能的细菌（Halothiobacillus，硫等）显著丰生长期间下的Hg供给增加⁰在模拟烟道和NO加油站。顺序化学提取工艺，电感耦合质谱法，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分散光谱法的综合应用证明，Hg ⁰最终被生物氧化为结晶的朱砂（β-HgS）细胞外微分子颗粒。我们的发现提供了机械上的见解，即MOB，DSOB和多功能细菌协同生物氧化了Hg ⁰作为Hg ²⁺的初始电子供体，并反硝化了NO作为N ₂的末端电子受体。SDB从S ₂ O ₃ ^2-分支成S ^2-和SO ₄ ^2-歧化S ⁰，从Hg ²⁺和歧化衍生S ^2-形成β- HgS ，热力学上有利于Hg ⁰生物氧化。这项新颖的生物技术可以替代烟气中的Hg ⁰和NO处理，是一种经济高效且环保的选择。

关键点

• Hg ⁰ 生物氧化和自养反硝化硫氧化的组合实现了Hg ⁰ 和NO的同时去除。

•硫代硫酸盐歧化反应增强了Hg ^0的 生物氧化，可去除Hg ⁰ 。

•汞氧化细菌，反硝化/硫氧化细菌和硫歧化细菌协同完成Hg ⁰ 和NO的去除。