Simultaneous removal of SO2 and NO in a rotating drum biofilter coupled with complexing absorption by FeII(EDTA)

• The maximal removal efficiency of SO2 and NO is up to 98.5% and 93%, respectively.
• FeII(EDTA) contributed to the NO mass transfer, the denitrification and the desulfurization.
• The dominant NR was Pseudomonas and SRB was Desulfovibrio.

A promising process of microbial desulfurization and denitrification integrated with complexing absorption is under the development for simultaneous removal of SO2 and NO in a rotating drum biofilter (RDB). The process employs FeII(EDTA) to improve the NO mass transfer, the denitrifiers bacteria (NR) for the denitrification, and the sulfate reducing bacteria (SRB) for the desulfurization. Experimental results demonstrated that NO removal efficiency was significantly improved from 57.1% to 93.0% in the presence of 10 mM FeII(EDTA) in the 60-day operation. Meanwhile, the SO2 removal efficiency reached around 90%. Parametric tests showed the maximal removal efficiency of SO2 and NO could be achieved at 98.5% and 93%, respectively, in the conditions of 2000 mg/m3 SO2, 800 mg/m3 NO, 1.8 min of empty bed residence time (EBRT), and 2 vol% oxygen. The microbial community analysis with the high-throughput sequencing indicated that the dominant denitrification bacteria with a maximal abundance of 35.7% were Pseudomonas which was mainly distributed in the external sphere of RDB and the dominant SRB was Desulfovibrio, which was mainly distributed in nutrient solution with a maximal abundance of 6.1%.