Nitrogen removal and mechanism of an extremely high-ammonia tolerant heterotrophic nitrification-aerobic denitrification bacterium Alcaligenes faecalis TF-1.

[Display omitted] • A HN-AD bacterium, Alcaligenes faecalis TF-1 was isolated from landfill leachate. • NH 4 +-N tolerance of the strain TF-1 reached 2000 mg·L−1 with 65% of NH 4 +-N removal. • 52.87% of NH 4 +-N removal was realized under 70 g·L−1 salinity and 919.20 mg·L−1 NH 4 +-N. • The optimum C/N, pH and carbon source of the strain were 16, 7 and sodium citrate. • HN-AD pathway of TF-1 was revealed: NH 4 +-N → NH 2 OH → NO → N 2 O → N 2. A novel heterotrophic nitrifying bacterium with high salt and high ammonia nitrogen tolerance, Alcaligenes faecalis TF-1, was isolated from the leachate of a landfill. The verification of nitrogen removal efficiency of different nitrogen sources and PCR amplification electrophoresis results showed that the HN-AD pathway of the strain TF-1 was NH 4 + → NH 2 OH → NO → N 2 O → N 2. The results of parameter optimization showed that the optimal nitrogen removal conditions were as follows: sodium citrate as carbon source, C/N = 16, pH = 7, and NH 4 +-N loading of 808.21 mg/L. The strain TF-1 could remove about 94.60% of ammonia nitrogen (1963.94 mg/L). The salinity tolerance range of the strain TF-1 was 0–70 g/L, and the removal efficiency was 52.87% at salinity 70 g/L and NH 4 +-N concentration 919.20 mg/L and 55.67% at pH = 10 and NH 4 +-N concentration 994.82 mg/L. The extreme environmental adaptability and remarkable nitrogen removal performance make this strain a promising candidate in leachate treatment. [ABSTRACT FROM AUTHOR]