A　novel　simultaneous　nitrification　denitrification　and　phosphorous　removal-sequencing　batch　reactor　(SNDPR-SBR)　enriched　with　PAOs　(phosphorus　accumulating　organisms),　DPAOs　(denitrifying　PAOs),　and　GAOs　(glycogen　accumulating　organisms)　at　the　ratio　of　2:1:1　was　developed　to　achieve　the　simultaneous　nutrient　and　carbon　removal　treating　domestic　wastewater　with　low　carbon/nitrogen　ratio　(＜=　3.5).　The　SNDPR　system　was　operated　for　120　days　at　extended　anaerobic　stage　(3　h)　and　short　aerobic　stage　at　low　oxygen　concentration　(2.5　h)　with　short　sludge　retention　time　(SRT)　of　10.9　d　and　hydraulic　retention　time　(HRT)　of　14.6　h.　The　results　showed　that　at　the　stable　operating　stage,　the　average　effluent　chemical　oxygen　demand　(COD)　and　PO43--P　concentrations　were　47.2　and　0.2　mg　L-1,　respectively,　the　total　nitrogen　(TN)　removal　efficiency　was　77.7%,　and　the　SND　efficiency　reached　49.3%.　Extended　anaerobic　stage　strengthened　the　intracellular　carbon　(mainly　poly-beta-hydroxybutyrate,　PHB)　storage,　efficiently　utilized　the　organic　substances　in　wastewater,　and　provided　sufficient　carbon　sources　for　denitrification　and　phosphorus　uptake　without　external　carbon　addition.　Short　aerobic　stage　at　low　oxygen　concentration　(dissolved　oxygen　(DO):　1　+/-　0.3　mg　L-1)　achieved　a　concurrence　of　nitrification,　endogenous　denitrification,　denitrifying　and　aerobic　phosphorus　uptake,　and　saved　about　65%　energy　consumption　for　aeration.　Microbial　community　analysis　demonstrated　that　P　removal　was　mainly　performed　by　aerobic　PAOs　while　N　removal　was　mainly　carried　out　by　denitrifying　GAOs　(DGAOs),　even　though　DPAOs　were　also　participated　in　both　N　and　P　removal.　(c)　2015　Elsevier　Ltd.　All　rights　reserved.