Isolation And Identification Of Bacteria With High Efficiency In The Removal Of Nitrogen From Wastewater Treatment System

By using BTB medium,25 strains of aerobic denitrifiers,20 strains of nitrobacterium and 8 strains of Biochemical bacteria were isolated from the MSG wastewater treatment plant and the SBR reactors denitrification system fast and efficiently. The result show that the removal rates of nitrate and the removal rates of TIN was higher than 60% by 15 strains of aerobic denitrifier. Ammonia nitrogen loss through heterotrophic nitrification in the liquid culture medium inoculated with 10 strains of aerobic denitrifier reached higher than 50%.The removal rates of Nitrogen was less than 50% by 20 strains of nitrobacterium. The removal rates of COD_cr was higher than 88% by 8 strains of Biochemical.The results of morphological and physiological features tests of the 15 bacteria that their nitrate and TIN removal rates was higher than 50% showed that 13 bacteria were Gram-positive and were found endospore, the remaining 3 bacteria were Gram-negative and were not found endospore. The cell of Gram-positive bacteria significantly larger than Gram-negative bacteria.their characteristics were basically the same: oxidase positive,indole negative, glucose ferment positive,deliquesce gelatin and break down proteins in the tryptophan indole arising. The use of different carbon sources for growth: the 9 strains of heterotrophic nitrification-aerobic denitrifier (WYLW1-2,WYLW1-3,WYLW1-4,WYLW1-6,WYLW1-9,WYLW1-10,WYLW2-4,LH2-1,LH2-3) can better use amino acid carbon source, have the ability of completion of nitrification and denitrification.In the light of its morphological and physiological features and Biolog system analysis as well as 16S rDNA sequences,15 strains of aerobic denitrifier were identified as Bacillus and Delfti.13 of that aerobic denitrifier were identified as Bacillus cereus, Bacillus megaterium and Delftia acidovorans. By PCR amplification and homology analysis of 16S rDNA sequence, the taxonomic status of the various strains were determined and the degree of homology with the standard strains were revealed.The result show that although the strains belong to the same genus, their nitrate and TIN removal rates and morphological and physiological features were differences.This was indicating the different sludge acclimation conditions will lead to a variety of enzymes of different strains, even in the same external conditions, due to the complexity of composition sludge system, the enzyme activity of various strains may have large differences.The method of strain identification by combination of the morphological and physiological features and Biolog system analysis as well as 16S rDNA sequences was reliable and reasonable.