A two-sludge denitrifying-phosphorus-removal system

integrated anaerobic/anoxic /aerobic process with biological aerated filter (AAO-BAF)

was used to treat domestic wastewater. By analyzing removal of COD and nutrients

the reactivation performance of AAO-BAF system was evaluated. The seed sludge with high content of denitrifying phosphorus accumulating organisms (DPAOs) had been deposited under room temperature for one month. Two start-up methods (denoted as 1# and 2#) were compared

for which the volume ratio of the anaerobic/anoxic/aerobic zone (Vr) of the AAO reactor was 2:5:2 and 2:6:1 respectively. AAO-BAF system exhibited good removal of COD and NH4+-N without obvious deterioration. At 17th day

TN and PO43--P removal reached 75% and 92% respectively with two start-up methods

while the amount of phosphate taken up per nitrogen denitrified increased from 0.5 to 1.5 mg PO43--P·(mg NO-3-N) -1. The results demonstrated that 1# was more suitable for the secondary start-up of AAO-BAF system

the corresponding COD

NH4+-N

TN and PO43--P removal efficiency reached 89%

99%

70% and 90% respectively at the 10th day. Furthermore

the results also showed that the sludge settling ability was also recovered more quickly for 1# than 2#.