An ammonia-oxidizing bacterium consortium showed approximately 100% removal of NH4+-N with an initial concentration of 262.28 +/- 8.21 mg.L-1 within 10 days, and only 16.54 +/- 0.52% of NH4+-N was converted to NO2--N in this study. The consortium removed ammonium by heterotrophic nitrification and aerobic denitrification (HNAD) without N2O emission. The activity of AOB was not affected by low concentrations of FA or FNA, but completely inhibited by 0.04 mg HNO2 center dot L-1. In a bioaugmentation treatment of eutrophic wastewater using the consortium, the removal efficiency of NH4+-N reached 90.85 +/- 0.8% and 77.88 +/- 1.86% at initial concentrations of 1.80 +/- 0.04 mg.L-1 and 40.31 +/- 0.57 mg.L-1, respectively, and the dissolved oxygen level had a significant impact on the consortium activity. No significant changes in the bacterial community structure were observed after the consortium addition, and local functional bacteria were enriched by aeration and contributed to ammonium nitrogen removal with AOB.