| In conventional biological phosphorus and nitrogen removal system, the phosphorus and nitrogen removal were considered as the process of contradiction and competition because of the different of condition and microorganism. These contradictions mainly showed on the competition for the organic substance. PHB as the cell carton could provide energy source and electron offerer for phosphorus absorption and the denitrifying of the nitrate in the denitrifying phosphorus remove system. Denitrifying dephosphatation made it possible to use COD more efficiently, since it combined two processes of carton resource requirement to one. Based on the theory, a fill-and-draw SBR system was used in this investigation. First was studied the effect of sludge age,concentration of the influent COD and anoxic nitrate concentration on the denitrifying dephosphatation. Then the connection between the translation of PHB and the process of denitrifying dephosphatation was studied. It was also discussed the correlation between the consumption of PHB and the quantity of denitrification phosphorous removal. The trait of denitrifying and dephosphatation were researched. Finally the mechanism of metabolizability and the kinetics is studied elementarily. The conclusions were as follows: (1)The test showed the better effect may be obtained when SRT was 30d, influent COD concentration was 220～300mg/l,influent phosphate was 5.20～9.36mg/l,anoxic nitrate concentration was 25mg/l . (2)The author also found that the increasing nitrate concentration not only could be favorable to remove phosphorous, and also improve the effect of the redundant COD on denitrifying phosphorus removal. There was a better linear correlation between the quantity of phosphorus absorption and nitrate denitrification: ΔPO43--P=0.52ΔNO-3-N-0.17, namely the translation of per 2mg nitrate could accelerate the absorption of 1mgP. (3) It is realized that PHB as cell depositor used to the processes of phosphorus and nitrogen removal system, as well as it reduced the low molecule organic carton competition between denitrifying and phosphorus release in anaerobic stage. (4) PHB had a significant influence on the process of denitrifying phosphorous removal. The better linear correlation was observed between the consumption of PHB and denitrification phosphorous removal ratio:ηp=7.05ΔPHB+33.99,ηN=5.94ΔPHB+50.87.It indicated that the change of anoxic PHB will affect the efficiency of denitrifyi0ng dephosphatation. The exponent correlation is also found between the consumption of PHB and the quantity dephosphorization or the denitrification: △P =2.22e0.025?PHB,△N =4.45e0.025?PHB. The ability of denitrifying dephosphorization will be affected directly if the low molecule organic carton could be provided enough in anaerobic stage. (5)The SOUR test showed the activity of the sludge would be worse when the sludge suffered the phase of anaerobic and anoxic depressive condition for the denitrifying phosphorous removal system. To be active, the system would sustain a definite ratio for aerobic phase. The author also found that the ecosystem is better when the ratio of aerobic stage is 6% in the denitrifying phosphorus removal system. (6)The mass-balance equations of each composition in anaerobic, anoxic and aerobic stage are established respectively, and then a series of dynamical models of each composition are built and computed. The result indicates that there is a good correspondence between the computed and measured values. The model shows great value of application to forecast the concentration of COD, phosphorus and nitrogen.
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