|Other Abstract||Compared with traditional bacteria, heterotrophic nitration bacteria had the advantage of higher
growing rate higher efficiency and lower requirement to the environment. However, researches on the heterotrophic nitration bacteria especially in water treatment were few at present. In this paper, the heterotrophic nitration bacteria in the surface layers of the integrated vertical flow constructed wetland were studied by traditional and molecular biology methods and two heterotrophic nitration bacteria, named by H-1, H-2, were isolated. The optimal nitrification effects were studied through physiology and biochemistry experiments, biolog experiments, 16S rDNA phylogenetic analysis and orthogonal experiments. The maim results were summarized as follows:
1. The heterotrophic nitration bacteria were screened by selective incubation media and two strains of heterotrophic nitrifier which had higher nitrification potential, named by H-1, H-2, were isolated from the surface layers of the integrated vertical flow constructed wetland. The heterotrophic characteristics were proven by C fountain in the biolog and their bacterial growth curve, the optimal C/N fountain, temperature and pH were also obtained.
2. The phylogenetic analysis based on 16S rDNA of H-1、H-2 suggested that the bacterial strain were 98% homology at the nucleotide level compared with 16SrDNA of Alcaligenes faecalis. It was thought that bacterial strains H-1and H-2 were possibly Alcaligenes A. faecalis.
3. Orthogonal experiments of four factors and three levels were designed to screen out the optimum nitration condition. The results indicated that the nitrosification effect was optimal when the temperature, pH, inoculation quantities and dissolved oxygen were 300 C, 7.5, 107 CFU and 2.25mg/L, respectively, with the sorting order being dissolved oxygen> temperature>pH> inoculation quantities; The influences of temperature and dissolved oxygen on nitrosification effect were extremely significant, while the influences of pH and inoculation quantities were quite slight. Referring to the nitrification effect, the optimal condition was obtained when the temperature, pH, inoculation quantities and dissolved oxygen were 200 C, 4.5, 107 CFU and 3.76mg/L, respectively, with the sorting order being dissolved temperature > pH > inoculation quantities > dissolved oxygen. The influences of pH and dissolved oxygen on nitrification effect were highly significant, while the influences of temperature and inoculation quantities on nitrification effect were relatively slight.|