The impact of nitrite (44.64

70.3

94.33

112.36 mg NO2--N·L-1) on denitrifying phosphorus removal metabolism was investigated by using 92%±3% polyphosphate accumulation organisms domesticated in acetate/propionic acid for 340 d.The results showed that denitrifying phosphorus removal metabolism also occurred when nitrite was used as electron acceptor at first

and the metabolism was inhibited when the concentration of nitrite increased.Nitrite reduction rate

phosphorus uptake rate and PHA degradation rate all reduced with initial nitrite increasing

and the complete inhibition concentration was higher than 112.36 mg NO2--N·L-1.Nitrite reduction rate and phosphorus uptake rate were 2.61 mg NO2--N·(g MLSS) -1·h-1 and 3.0 mg PO43--P·(g MLSS) -1·h-1 at initial 112.36 mg NO2--N·L-1.N2O was produced in the denitrifying phosphorus removal process.Initial nitrite stimulated nitrite reduction to exceed N2O reduction rate

resulting in greater quantities of N2O production.The proportion of N2O-N/TN were 63.5%

49.0%

30.2%

24.0% respectively corresponding to initial concentration of 44.64

70.3

94.33

112.36mg NO2--N·L-1.The accumulation of N2O could be transformed to N2 in order to improve denitrification when the system had enough substrate and extended anoxic mixing time.