The removal of wastewater nutrients in the modified UCT step feed process was investigated when treating municipal wastewater.Based on experimental data under steady-state conditions

the equations for calculating material balances of COD

nitrogen and phosphate were established.These three material distributions in the system were also evaluated.The results indicated that with stable effluent quality and good capacity of resistance to shock load

the effluent concentrations of COD，TN and TP were 43.5

8.51

0.29 mg·L-1 on average

respectively

which the first level A discharge standard of pollutants for municipal wastewater treatment plant was met.Furthermore

according to calculation equations and transformation pathways of nutrients

it was found that approximately 67.1% of nitrogen was successfully removed during the denitrification process

including anoxic denitrification process and simultaneous nitrification and denitrification (SND) process

which greatly contributed to high nitrogen removal efficiency.COD consumed in the denitrification and phosphate release process accounted for 62.1%

which embodied the advantage of sufficient utilization of influent carbon sources.Both nitrogen and COD balance ratios were as high as 99.8%

which confirmed the validity of equations established.Phosphate removal was mainly achieved by the discharge of excess sludge

accounting for 71.7% of the total.