Low-strength influence on nitrogen removal performance and bacterial community structure of the anammox process

Abstract

The effect of low strength on anaerobic ammonium oxidation (anammox) was investigated in an anaerobic moving bed biofilm reactor (AMBBR) treating artificial wastewater. Influent ${\mathrm{NH}}_4^{+}$-N concentration with 10.74 ± 2.73 mg L^-1 adversely impacted nitrogen removal permanence, the total nitrogen removal efficiency was significantly increased from 61.4% to 80.0%, when influent nitrogen increased to 22.36 ± 5.83 mg·L^-1. ${\mathrm{NH}}_4^{+}$-N removal efficiency decreased obviously while that of ${\mathrm{NO}}_2^{-}$-N was basically unaffected by the influent nitrogen concentration decrease. Illumina high-throughput sequencing results revealed that the predominant bacterial (64.71%) phylum was Proteobacteria and the dominant functional microorganisms were Nitrosospira, Nitrospira, and Candidatus Brocadia. Simple model simulation results showed that the inhibition effect of the low substrate was most likely due to the increase of bulk DO, which comes from influent and gas-liquid transfer. The reversible inhibition effect of low strength on nitrogen removal performance in an anammox reactor was demonstrated, and strictly regulation of the bulk DO was presumed to be critical to achieve a successful and stable operating performance under low strength.

Keywords: Anammox; aquasim model; dissolved oxygen; microbial community structure; substrate concentration.