Abstract: To increase the biological nitrogen removal efficiency of these saline wastewater, a heterotrophic nitrification bacterium was enriched and isolated from industrial wastewater sludge. The strain was characterized by Gram staining and molecular biology. The 16S rRNA gene sequencing results were analyzed in Blast database for homology and a phylogenetic tree was constructed. The effects of carbon source type, different C/N, initial pH, temperature and NaCl concentration on the denitrification effect of the strain were studied. The results showed that the isolated heterotrophic nitrobacteria strain wasAlcaligenessp., named XN-1. Both the maximum NH+4-N removal rate and the maximum cell growth were obtained under sodium acetate with the values of 100% and 0.42, respectively When C/N 15－20, with initial pH 7－10, temperature at 30－35 ℃, and salinity in the rang of 0－4%, the highest ammonia nitrogen removal rate of 100% was obtained. Strain XN-1 had highly efficient heterotrophic nitrification ability and great potential in nitrogen removal treatment of saline wastewater.

Key words: heterotrophic nitrification, ammonia nitrogen degradation, isolation and identification, high salt