| Global problem of eutrophication disturbed and destroyed the utility value of water resources seriously, and brought tremendous harm to economic development and human health. People were gradually convinced of the importance of control of the concentration of nitrogen and phosphorus in the sewage. Study on nitrogen and phosphorus removal technology which is of high efficiency, low consumption and no secondary pollution was one of the hot subjects in the field of water treatment. Recently, the discovery of the denitrifying phosphorus removal phenomenon provided new directions and ideas for the exploitation of novel biological nitrogen and phosphorus removal process.Based on the theory of denitrifying phosphorus removal, necessary conditions of acclimation and enrichment of denitrifying phosphorus removing bacteria were investigated by the anaerobic/anoxic sequencing batch reactor. The start-up tests indicated that some denitrifying phosphorus removing bacteria existed in the conventional nitrogen removing sludge. Denitrifying phosphorus removing bacteria could be dominant microflora quickly though appropriate cultivated conditions which mainly included the anaerobic/anoxic alternative circumstance and suitable carbon and nitrogen concentration. At stale status of the system, when the minimum carbon source was used, the ratio of COD: P: Nwas 250: 6: 10.5 and the removal efficiency of carbon, nitrogen, and phosphorus were higher than 90%. SRT, nitrate, and COD were investigated which were the main impact factors of the denitrifying phosphorus removal system, and the mechanism of these factors effect on the system were discussed through the tests. The status and development of the system was analyzed under the disturbance of these factors, and the stability of the A2SBR denitrifying phosphorus removal system and evaluation method of stability were investigated systematically. Shown by the tests, the denitrifying phosphorus removal system was a flimsy system and operation control of the process was crucial. The main condition of stable operation of denitrifying phosphorus removal system was proper sludge age and the concentration of nitrate in the effluent. In the tests, when the concentration of COD in the influent was at the range of 250 mg/L to 350 mg/L, SRT was about 18 day, and the concentration of nitrate was at the range of 1.5 mg/L to 7 mg/L, the system achieved stable operation status. Forty-eight strains were isolated from the activated sludge produced in the anaerobic/anoxic sequencing batch reactor under stable operation. The isolated strains were tested with phosphorus uptake assay, the experiment of denitrifying nitrates to gas and inspection of metachromatic and Polyphydroxybutyrate (PHB) granule, four effective DPB were screened out ultimately. They are H16,H19,H24 and Xg. H16, H19and H24 were Pseudomonas sp. and Xg was Enterobacter sp. in terms of its physiological and biochemical testing results.Growth curve of strain were determined by absorbency and their generation time were separately 4.6h, 9.4h, 11.4h and 9.1h.More important abiotic factor (temperature and pH ) that effect H16, H19, H24 and Xg on growth and phosphorus removal ratio were studied. For four strains growth and phosphorus removal, the better temperature range was from 20℃to 40℃, and the best temperature was about 25℃. So influence of temperature is limited in process of application of DPB to wastewater treatment. But pH value that effects H16, H19, H24 and Xg on growth and phosphorus removal rate are remarkable. The optimal pH value of growth and phosphorus removal of H16, H19 and Xg is 7.0, in respect of H24, the best pH is neutral or a bit alkaline.Then, these strains were domesticated and cultivated in the shaking bed by gradually bringing down the low temperature to 8℃. In this process, two strains (H16 and H24) were screened out in terms of the amount of increment and effect of dephosphorization. the influence on the amount of increment and the effect of dephosphorization of growth factor and pH is mensurated in the condition of 8℃.The result shows that the existence of growth factor effects on H24 much more and almost don't effects on H16. pH of the culture medium impact much more on the dephosphorization ratio of H16 and H24. When the pH value was 7.0, the growth condition and the effect of dephosphorization were all very good. But the optimum pH to H24 is neutral or a bit alkaline. H16 and H24 are psychrophile in terms of research on temperature ecological amplitude.
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