Simultaneous removal of SO2 and NO from flue gas can be biologically achieved by the rotating drum biofilter with FeⅡ(EDTA) as a solvent.One issue related with this process is the generation of H2S.To control its generation,the pathways of H2S formation was investigated,and the parametric tests were conducted.The addition of FeⅡ(EDTA) (10 mM) increased the removal efficiency of NO and SO2,while the S2-concentration decreased from 81 mM to 3.5 mM.The parametric tests showed that the high NO concentration favored the SO2 removal and significantly inhibited the H2S generation.High-throughput sequencing showed that the dominant denitrifying bacteria were Pseudomonas (9.09%),and the main sulfate-reducing bacteria were Desulfovibrio (5.84%).The long-term operation confirmed that the system could effectively simultaneous perform biological denitrification and desulfurization,and the H2S could be controlled.