Performance of an autotrophic denitrification process with mixed electron donors and a functional microbial community

A moving bed biofilm reactor (MBBR) using Mn(II) and Fe(II) as mixed electron donors was designed for nitrate removal. The optimal state, as determined by response surface methodology, was an Fe(II):Mn(II) molar ratio of 0.62, electron donor: electron acceptor molar ratio of 2.62 and hydraulic retention time of 10.88 h. Subsequently, the MBBR was applied to groundwater treatment and demonstrated a final nitrate-N removal efficiency of 99.5% with a nitrite-N accumulation rate of 0.0706 mg-N.L-1.h(-1). Furthermore, high-throughput sequencing was employed to characterize bacterial communities in the MBBR. Results showed that the genera of Pseudomonas and Acinetobacter may make a contribution to the nitrate removal.