Abstract: StrainPseudomonassp. TE-5 (TE-5), exhibiting both heterotrophic nitrification and aerobic denitrification (HN-AD) capabilities, was isolated and screened from the aerobic tank of a municipal wastewater treatment plant. Strain TE-5 was taxonomically identified asPseudomonassp. via 16S rDNA gene sequencing. Through single-factor experiments, the optimal range of growth and nitrification conditions for the strain was preliminarily determined. Sodium citrate was identified as the optimal carbon source. The cultural conditions were C/N 8－12, pH 6－9, speed 120－140 r/min, temperature 25－35 ℃, and inoculum dose 2%－4% (volume ratio). Under the above environmental conditions and with an initial ammonia nitrogen mass concentration of 100 mg/L, the nitrogen removal efficiency exceeded 96% within 10 h. The multi-environment parameter interactions of the strain were optimized by combining the Plackett-Burman design (PBD) experiment, the steepest ascent path method (SPAM) experiment, the response surface method (RSM) experiment, and the optimal initial environmental parameters of the strain were determined. RSM experiment optimization results indicated that, with an initial ammonia nitrogen concentration of 100 mg/L, the strain achieved a nitrogen removal efficiency of 90.96%±2.82% at 7 h under the following optimal conditions: pH 9.08, shaking speed 142.27 r/min, and inoculum dose 3.56% (volume ratio). After 10 hours, the nitrogen removal efficiency reaches 100%. The results indicate that strain TE-5 possesses good HN-AD performance and exhibits high application potential in wastewater biological treatment.

Key words: biological denitrification, heterotrophic nitrification, aerobic denitrification, Plackett-Burman design, response surface