Domestication, Separation And Optimization Of Nitrogen And Phosphorus Removal Bacteria

As science and technology development and the improvement of living standards, environmental pollution is also increasing. In recent years, nitrogen and phosphorus compounds contribute to water pollution are common occurrences in lakes, reservoirs and rivers around the world; the development trend of eutrophication is also very fast.Therefore, in the last half century, more and more countries have carried out environment protection work. It has become a major industrial and agricultural ways in the use of microbial treatment of sewage. Nowadays, it is not only to remove the organic pollution (COD), high concentrations of nitrogen and phosphorus removal also put forward higher requirements in the sewage treatment process. Therefore, it is imperative to improve the water treatment system and to establish a complete selection and optimization of microbial acclimation method.In this study, using General granular sludge and the sewage through the manual configuration in a sequencing batch reactor (SBR), at a temperature of 25℃, pH 7 to 8, after 100 days of acclimation, in which the first 40 days training phase,60 days after the adjustment period. In the adjustment period, COD, ammonia nitrogen and phosphate in the water were:250mg/L,50 mg/L, 14 mg/L, it is twice the training phase. After acclimation of one hundred days, the sludge volume index (SVI) stabilized at about 20mg/L, the mixture of volatile suspended solids (MLVSS) is about 2500mg/L, COD, ammonia nitrogen, phosphate, the average removal rates reached:92.4%, 88.1%,95.9%, the effluent concentrations stabilized at about:19.0mg/L,5.95mg/L,0.57mg/L, COD and ammonia nitrogen concentration reached the first level emission standards, while phosphate reached the second level emission standards.Sludge from the domestication successfully isolated six growing well bacteria by the separation of nitrogen and phosphorus SPECIFIC medium, in which three strains of good performance for the removal:N-1, N-2, N-3, the other three strains for the better phosphorus removal performance:P-1, P-2, P-3. Then, we screening obtained the best performance of an ammonia removal bacteria N-2, which by testing first three bacterial removal performances. And through optimization, come to the best temperature is 30℃, pH 7, and ammonia nitrogen removal efficiency reach 94.9% within 24 hours. The same way, we also screening obtained the best performance of phosphorus removal bacteria P-3, which is optimized for the best carbon source is glucose obtained, the best temperature is 30℃,pH 7, and the final in 12 days, the phosphate removal rate reached 95.9%, and N-2 and P-3 by Gram staining and 16S rDNA sequence analysis identified the type of bacteria, the results show:N-2 is Raoultella ornithinolytica, P-3 is Klebsiella ornithinolytica, two strains of bacteria in Gram stain were negative. In addition, after analysis the degradation products of these two bacterial, we can determine that N-2 is a nitrosation bacteria, and P-3 is a denitrifying phosphorus removing bacteria, it has the role of denitrification and phosphorus removal.