[Comparison of heterotrophic nitrification and aerobic denitrification system by strain qy37 and its accelerating removal characteristic of NH4+ -N].

The characterization in nitrogen removal of a heterotrophic nitrification-aerobic denitrification bacteria (qy37) was studied. A strain coded as qy37 which had simultaneous heterotrophic nitrifying and aerobic denitrifying ability was screened. In the light of its morphological and physiological characters as well as their sequence analysis of the 16S rDNA, strain qy37 was identified as Pseudomonas sp.. In heterotrophic nitrifying system utilized ammonium chloride as nitrogen source, the concentration of NH4+ -N reduced from 138.52 mg/L to 7.88 mg/L and COD reduced from 2408.39 to 1177.49 mg/L by strain qy37 in 32 hours, the maximum accumulation of NH2OH and NO2- -N were 9.42 mg/L and 0.02 mg/L respectively, it was speculated that NH2OH was transformed to N2O and N2 directly by strain qy37. In aerobic denitrifying system utilized sodium nitrite as nitrogen source, the concentration of NO2- -N reduced from 109.25 mg/L to 2.59 mg/L by strain qy37 in 24 hours, and the maximum accumulation of NH2OH was 3.28 mg/L. Compared with heterotrophic nitrifying system, aerobic denitrifying system had a higher bacterial growth whereas the lower removal rate of TN and COD, as well as the accumulation of NH2OH. NO3- -N was also detected in aerobic denitrifying system. It is considered that the upgrowth of bacterium and utilization of energy in aerobic denitrifying system were more efficient than that in heterotrophic nitrifying system. In heterotrophic nitrification-aerobic denitrification system, the removal rate of NH4+ -N improved 37.31% in 16 hours than that in heterotrophic nitrifying system, the accumulation of NH2OH was less but N2O was higher than that in both heterotrophic nitrifying system and aerobic denitrifying system.