Fig. 4: Performance and analysis of microbial community of the two-stage coupled system.

a The concentrations of NO3−-N, NH4+-N, NO2−-N and SCN−; b NLR (nitrogen loading rate), NRR (nitrogen removal rate) and TNRE (total nitrogen removal efficiency). The analysis of microbial community in R2 from metagenomic sequencing data during operation of the two-stage coupled system at (c) phylum level, d genus level and (e) species level.