Isolation Of Heterotriophic Nitrifying Bacteria And Characters Of Removal Of Ammonia

In this paper, a stain of heterotrophic nitrifying bacteria was isolated, which was Gram-negative. The cells of strain were observed by SEM and appeared as short rods (approximately 2.72μm×1.08μm). Based on partial 16S rDNA sequences, the results suggested that the strain S3 belong to the genus Alcaligenes, and S3 was named Alcaligenes sp. S3.The character of COD and ammonia of removal of Alcaligenes sp.S3 was studied and the results are as follows.(1) The lag phase of S3 was short, about 2 h. In the 50 h, the stain S3 reached the growth maximum, with the concentration of biomass 1.4 mg/L. In the 120 h, the S3 went into decline phase. When the experiment was finished, the COD removal rate was 95.69%, and the NH4+-N removal rate was 79.07%.(2)NH2OH, NO3-N and NO2-N could not be utilized. The total nitrogen was removed about 29%in the N-balance experiment.(3) In the experiments of Fe3+and sodium thiosulfate added, significant difference was observed. It was deduced that Fe3+might reduce NO2-N accumulation, and sodium thiosulfate might restrain the process of NH2OH-oxidizing into NO2-N.(4) Alcaligenes sp. S3 grew well at pH 9, and the nitrogen-removal arrived highest at the C/N ratio 12, and the shaker speed had little influence on the removal nitrogen. The nitrogen-removal ratio was higher with sodium succinate used.(5) Theμmax of Alcaligenes sp.S3 was 0.236 h-1, and theγmax was 1.611 mgL-1h-1. When fitting with fist-order kinetics at different concentrations of ammonia nitrogen, the removal rate of ammonia nitrogen was fitted better only at higer concentration.(6) Alcaligenes sp. S3 grew badly in acidic environment, and grew well at pH 7.5-10 values. The shaker speed had little effect on the removal efficiency of ammonia nitrogen, but the C/N ratio had great influence on the removal efficiency.