| The SBR nitrosation experimental equipment was established to investigate the performance of the nitrite as electron acceptor on removal of phosphorous in nitrosation denitrifying phosphorus removal(NDPR) system. The nitrite, of which concentration was designed for5,10,15,20,25,30,40,45,100mg/L was used to cultivate and domesticate the denitrifying phosphorus removal system. In addition, the inhibiting factors and mechanism of the phosphorus removal effect were studied from the Angle of dynamics. With different electron acceptors of nitrite nitrogen and nitrate nitrogen, the removal rate of COD, denitrification rate and denitrifying phosphorus absorption rate in denitrifying phosphorus removal system were investigated. The main conclusions were as follow:(1) In the range of suitable concentration of NO2-N and NO2-N, both of them could become electron acceptor in DPB and result in good denitrifying phosphorus removal after a long time of domestication.(2) When the concentration was less than15mg/L, the consumption of N02-N and denitrification rate increased with the increase of initial concentration of NO2-N; when the concentration was more than15mg/L, the consumption of NO2-N and denitrification rate decreased with the increase of initial concentration of NO2-N; when the concentration was at15mg/L, the denitrification rate of NO2-N become significantly lower, and the consumption of NO2-N showed a certain value. This phenomenon indicated the denitrification was inhibited when the concentration of electron acceptor was more than15mg/L.(3) The Phosphorus release rate and phosphorus uptake increased significantly when the concentration of NO2-N was5mg/L to15mg/L. when the concentration of NO2-N was more than15mg/L, the phosphorus release rate and phosphorus uptake decreased with the increase of the concentration of NO2-N and got the best effect at the concentration of15mg/L, which showed a similar performance of study on denitrification.(4) There was a good linear relationship between the aerobic phosphorus uptake and anaerobic phosphorus release amount. The straight line equation was imitatived by y=0.5806+1.6974x, which show a linear correlation between the two processes.(5) Under19mg/L of N02-N concentration, the relative activity of the RA was75%, belong to moderate inhibition; with NO2-N concentration of42mg/L, the RA was40%, belong to the severe suppression. RA was25%the relative inhibitory concentration of80mg/L.(6) The inhibition of denitrifying phosphorus removal by NO2-N concentration was conformed to the model of the noncompetitive inhibition of substrate, the dynamic model equations of which was and the kinetic parameters were μmax=2.02mg/(g-min)-1; Ks=507.05mg/L; Ki,s=0.263mg/L, respectively.(7) In this study, the inhibitionof denitrifying dephosphatation which the nitrite acted on conformed to the model of the noncompetitive inhibition of substrate, which was mostly effected by the inhibition of enzyme activity. However, the inhibitory effect mechanism was not very clear. How inbibitional effect the metabolism and mechanism performed, were still under clear.(8) The COD removal rates were close to each other using NO2-N or NO3-N as electron acceptor at room temperature (24±0.5℃). the COD removal efficiency showed very well and the carbon source was very sufficient at the start of anoxic period.(9) The consumption rate of the two electron acceptors of nitrates and nitrites was different. The consumption rate of nitrates as electron acceptor was a little higher than that of nitrites, but both of them show a good denitrification. In the process of denitrification, the form of nitrate nitrogen was firstly converted to nitrite nitrogen, then it was finally denitrified into nitrogen but the nitrite nitrogen was directly converted to nitrogen.(10) Within the inhibiting concentration of nitrite and nitrate, anoxic phosphorus absorption of both were effective. Anoxic phase with nitrite as electron acceptor, was more effective than that of nitrate in nitrosation denitrifying phosphorus removal(NDPR) system, which indicated that nitrite could take the place of nitrate as electron acceptor to denitrify phosphorus removal as long as the appropriate condition was given. |
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