A　novel　system　integrating　anaerobic/anoxic/oxic　(A(2)/O)　and　biological　aerated　filter　(BAF),　which　could　solve　the　sludge　retention　time　(SRT)　conflicting　problem　between　nitrifiers　and　polyphosphate　accumulating　organisms　(PAOs)　by　shortening　SRT　for　PAOs　in　A(2)/O　and　lengthening　SRT　for　nitrifiers　in　BAF,　was　investigated　in　this　study.　Various　nitrate　recycling　ratios　(100%,　200%,　300%　and　400%)　were　applied　to　a　lab-scaled　A(2)/O-BAF　system　to　detect　the　simultaneous　biological　nitrogen　and　phosphorus　removal　performance　while　treating　real　domestic　wastewater　with　low　carbon　to　nitrogen　(C/N)　ratio.　The　concentrations　of　chemical　oxygen　demand　(COD),　NH4+-N　and　total　phosphorus　(TP)　in　the　effluent　were　less　than　50.0,　0.5　and　0.5　mg/L,　respectively,　throughout　the　experiments.　The　removal　efficiencies　of　total　nitrogen　(TN)　were　64.9%,　77.0%,　82.0%　and　87.0%,　under　respective　nitrate　recycling　ratios　(increasing　from　100%　to　400%).　By　contrast,　nitrate　recycling　ratios　had　neglectable　effect　on　the　removal　efficiencies　of　COD　and　NH4+-N.　(C)　2011　Elsevier　Ltd.　All　rights　reserved.