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

Abstract Thermophilic membrane biofilm reactor (TMBR) for elemental mercury (Hg 0 ) 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 Hg 0 and NO removal in the TMBR were evaluated. TMBR achieved effective simultaneous Hg 0 and NO removal in 210 days of operation, Hg 0 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 (Hg 2+ ) from mercury oxidation. TMBR used oxygen as electron acceptor, NO and Hg 0 as electron donor in nitrification; O 2 , NO and NO 3 − could be used as electron acceptor and Hg 0 as electron donor in denitrification.