Simultaneous removal of elemental mercury and NO by mercury induced thermophilic community in membrane biofilm reactor

• Published in: Ecotoxicology and environmental safety 2019-07, Vol.176, p.170-177
• Main Authors: Wei, Zaishan, Yu, Shan, Huang, Zaishan, Xiao, Xiaoliang, Tang, Meiru, Li, Bailong, Zhang, Xiao
• Format: Article
• Language: English
• Subjects: Functional genes; Hg0 and NO removal; Mechanism; Mercury induced thermophilic community; Thermophilic membrane biofilm reactor
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2019.03.082

Thermophilic membrane biofilm reactor (TMBR) for elemental mercury (Hg0) and NO removal in simulated flue gas was investigated at oxygen content of 6% and 60 °C. The performance, the microbial community structures, gene function and the mechanism for Hg0 and NO removal in the TMBR were evaluated. TMBR achieved effective simultaneous Hg0 and NO removal in 210 days of operation, Hg0 and NO removal efficiency were up to 88.9% and 85.3%, respectively. Mercury induced thermophilic community had been formed significantly. Comamonas, Pseudomonas, Desulfomicrobium, Burkholderia and Halomonas were thermophilic mercury resistant bacteria. Brucella, Paracoccus, Tepidiphilus, Proteobacteria, Pseudomonas and Symbiobacterium were nitrifying/denitrifying genera, and had functional genes of mercury and nitrogen metabolism, as shown by16S rDNA and metagenomic sequencing. The biofilm in TMBR was characterized by XPS, HPLC. XPS and HPLC spectra indicate the formation of a mercuric species (Hg2+) from mercury oxidation. TMBR used oxygen as electron acceptor, NO and Hg0 as electron donor in nitrification; O2, NO and NO3− could be used as electron acceptor and Hg0 as electron donor in denitrification. •Thermophilic membrane bioreactor achieved Hg0 and NO removal simultaneously.•Mercury induced community had been formed significantly.•XPS and HPLC spectra indicate the formation of a mercuric species from mercury oxidation.•The mechanism for Hg0 and NO removal was proposed.