Performance, kinetic characteristics and bacterial community of short-cut nitrification and denitrification system at different ferrous ion conditions

Abstract In order to explore the operation performance, kinetic characteristics and bacterial community of the short-cut nitrification and denitrification (SND) system, the SND system with pre-cultured short cut nitrification and denitrification sludge was established and operated under different ferrous ion (Fe (II)) conditions. Experimental results showed that the NH4+-N removal efficiency (ARE) of SND system was 97.3% on Day 5 and maintained a high level of 94.9%±1.3% for a long operation period. When the influent Fe(II) concentration increased from 2.3mg L-1 to 7.3mg L-1, the sedimentation performance, sludge concentration and organic matter removal performance were improved. However, higher Fe(II) of 12.3mg L-1 decreased the removal performance of nitrogen and CODCr with the relative abundance of Proteobacteria and Bacteroidetes decreased to 30.28% and 19.41% , respectively. Proteobacteria, Bacteroidetes, Firmicutes were the dominant phyla in SND system. Higher Fe(II) level of 12.3 mg L-1 increase the RA of denitrifying genus Trichococcus (33.93%), and the denitrifying genus Thauera and Tolumonas dominant at Fe(II) level of no more than 7.3 mg L-1.