With the deterioration of eutrophication in China

nitrogen and phosphorus removal from wastewater have caught more and more attention

while influent C/P ratio is one of the most important influence factors. To investigate the effects of feed water C/P ratio on the performance of anaerobic-anoxic-oxic process

four different feed water C/P ratios were designed

that is 55

45

34

23

so as to study the variations of COD

TN

PO3-4-P and sludge characteristics with the C/P ratio. The results showed that when the C/P ratio was lower than 32

P removal efficiency increased as C/P ratio increased linearly

while the C/P ratio was higher than 32

the P removal efficiency maintained at 90%～98%

and effluent P concentration was lower than 0.5 mg8226;L-1.In contrast

regardless of the C/P ratio

excellent COD (90%) and good total nitrogen removal (75%～84%) were maintained throughout the experiments.However

P percentage in the wasted activated sludge (WAS) increased as the C/P ratio decreased. It was also found that denitrifying P removal existed under different C/P ratios by controlling the operation

and nitrogen and phosphorus removal efficiency could be improved.