Characteristics of a novel heterotrophic nitrification and aerobic denitrification bacterium and its bioaugmentation performance in a membrane bioreactor

[Display omitted] •A novel HNAD bacterium was isolated and identified as Acinetobacter sp. TSH1.•Strain TSH1 could efficiently remove NH4+-N, NO2−-N and NO3−-N.•Most of NH4+-N were converted to gaseous nitrogen by strain TSH1.•The strain TSH1 significantly enhanced the nitrogen removal efficiency. A novel bacteria with heterotrophic nitrification and aerobic denitrification ability was obtained from a membrane bioreactor (MBR) and identified as Acinetobacter sp. TSH1. The nitrogen removal characteristics, nitrogen balance analysis, kinetic characteristics, and enhanced biological treatment in MBR of the novel isolated strain TSH1 were determined. Results showed that strain TSH1 could remove approximately 96.6% of NH4+-N, 82.9% of NO2−-N and 98.7% of NO3−-N in 24 h, and the corresponding maximum removal rates were 3.64 mg-N/(L·h), 1.77 mg-N/(L·h) and 3.94 mg-N/(L·h). The nitrogen balance analysis indicated that most of NH4+-N (62.6%) and NO3−-N (71.9%) were transformed to gaseous nitrogen. The kinetic experiments showed that strain TSH1 had a high Km of 151.64 mg-NH4+-N/L and 203.25 mg-NO3--N/L. The enhanced biological treatment of synthetic wastewater in MBR showed that the strain TSH1 can significantly improve the nitrogen removal efficiency.