Abstract: A heterotrophic nitrification-aerobic denitrification （HN-AD） strain,Halomonassp. MY11, with tolerance to high salt and high ammonia nitrogen was successfully screened from a chemical wastewater treatment plant. The growth characteristics and denitrification performance of strain MY-11 were investigated by a one-factor-at-a-time experimental design, and the strain was able to grow and exhibit HN-AD activity under different environmental conditions, and the optimal culture conditions were determined as follows: carbon source of sodium succinate, C/N of 10－18, pH 7－9, shaker speed of 140－220 r/min, incubation temperature of 30－34 ℃, inoculum amount of 1%－5% （volume ratio）, and salinity of 2%－8%. Under these conditions, the removal efficiency of the strain for both NH+4-N and NO－3-N reached more than 99% within 30 h. The strain could grow under high-salt （4% salinity） and high-ammonia-nitrogen （1200 mg/L） conditions, exhibited high nitrogen removal efficiency, and could also adapt to various inorganic salt environments. It is demonstrated that strain MY-11 had excellent HN-AD performance and showed significant application value in the field of biological treatment of high-salt and high-nitrogen industrial wastewater.

Key words: heterotrophic nitrification-aerobic denitrification, salt tolerance, high ammonia nitrogen tolerance, biological nitrogen removal, complex wastewater