A　ENDPR　system,　combining　anaerobic-anoxic-oxic　reactor　with　an　external　nitrification　biological　aerated　filter　(AAO-BAF),　was　developed　to　treat　real　domestic　wastewater.　The　effluent　was　discharged　after　full　nitrification　in　BAF,　while　nitrogen　and　phosphorus　removal　by　denitrifying　phosphorus　accumulating　organisms　(DPAOs)　in　the　AAO　reactor　was　achieved.　To　optimize　aeration　rate　in　the　denitrifying　phosphorus　removal　(DPR)　reactor,　oxidation-reduction　potential　(ORP)　and　DO　was　examined.　When　the　aeration　rate　dropped　to　20　L　h(-1),　the　phosphorus　removal　deteriorated　greatly.　During　this　phase,　the　polyphosphate　(poly-P)　amount　in　the　sludge　was　reduced　by　43%　due　to　incomplete　phosphorus　uptake　and　the　secondary　phosphorus　release.　After　increasing　the　aeration　rate　to　30　L　h(-1),　the　abilities　of　anaerobic　phosphorus　release　and　anoxic　phosphorus　uptake　were　both　improved.　Results　demonstrated　that　AAO-BAF　could　be　operated　stably　with　high　removal　efficiencies　of　NH4+　(99%),　TN　(80%),　and　PO43-　(94%)　with　low　carbon　requirement　(COD/N　ratio　=　4.0)　and　low　aeration　rate　(DO　=　0.5　mg　L-1,　in　AAO　reactor).　(C)　2014　Elsevier　B.V.　All　rights　reserved.