Anoxic Phosphorus Uptake Characteristics of Sludge in Denitrifying Phosphorus Removal

Activated sludge of a bench-scale SBR,which was dominated by denitrifying phosphorus removing bacteria(DPB),was studied about its performance of anoxic phosphorus uptake.The findings of the experimental study showed that under the anoxic condition,nitrate could be used as electron acceptors to uptake P completely when utilized by DPB,with the rate much faster than that of aerobic P uptake;while nitrite was used as electronic acceptors with the rate as fast as that of nitrate on condition that nitrite concentration was as low as 10.6 mg/L,otherwise,inhibition of denitrifying P removal would be caused by higher concentration of nitrite(22.6 mg/L).Appropriate increases of MLSS could speed up anoxic P uptake rate while over-high MLSS would reduce specific rate of nitrogen and P,so MLSS should be controlled within a reasonable range.