The influence of influent nitrate on phosphorus removal efficiency of phosphate reduction systems under anoxic and aerobic condition was studied by changing the concentration of influent nitrate. It was shown that nitrate had significant influence on phosphorus removal efficiency of phosphate reduction system under anoxic and aerobic condition. When influent nitrate concentration was between 105 mg/L and 160 mg/L

it was favorable to anoxic phosphate reduction. However

influent nitrate had a remarkable inhibition on aerobic phosphate reduction

and there was a significant negative correlation between them (R2=0.982 7). The difference on phosphorus removal efficiency was mainly due to different influence of nitrate on microenvironment structure under various oxygen environments. Moreover

different concentrations of influent nitrate also affected the pH value in the reactor

which can affect phosphate reduction process. It was found that slight alkaline (pH around 8) was favorable for phosphate reduction under anoxic and aerobic condition.