EFFECT OF NITRIFICATION LIQUID REFLUX RATIO ON DENITRIFICATING PHOSPHORUS REMOVAL IN AN A2 /O-MBBR PROCESS

With an enhanced biological phosphorus removal system ( A2 /O-MBBR) ， the paper studied the effect of different nitrification liquid reflux ratio on denitrifying phosphorus removal． The results showed that in the condition of COD of 400 mg /L， NH + 4 －N of 30 mg /L，SOP of 8 mg /L，nitrification liquid reflux ratio of A2 /O-MBBR process had a little effect on the removal rate of COD，NH + 4 －N and TN． The phosphorus absorption amount of anaerobic pool increased with increasing reflux ratio． When reflux ratio increased to 200%( NO － 3 －N = 4 mg /L) ，the amount was 20. 2 mg /L and the maximum utilization of PHB was 1. 12 g /( g·L) and had the best metabolic activity． The system of A2 /O-MBBR was proved to have significant denitrifying phosphorus removal capacity．