Limited　filamentous　bulking　under　low　dissolved　oxygen　(DO)　is　a　new　technology　for　energy　saving　and　high　quality　effluent.　In　order　to　investigate　the　feasibility　of　this　technology,　four　sequence　batch　reactors　(SBRs)　were　occupied　to　operate　at　different　regimes　to　stimulate　different　processes　under　low　DO　(0.5　mg/L).　Sludge　settleability,　floc　structure,　pollutant　removal　and　aerated　energy　consumption　were　investigated.　The　results　showed　that　limited　filamentous　bulking　under　low　DO　was　hard　to　realize　in　the　single-stage　aerobic　reactors　for　they　were　prone　to　bulking　severely,　while　it　could　be　achieved　stably　in　the　pre-denitrification　reactors　when　the　feed　length　was　between　60　and　90　minutes.　Compared　with　normal　sludge　at　the　same　DO,　limited　filamentous　bulking　sludge　acquired　by　low　DO　displayed　its　high　energy-saving　effect.　In　addition,　the　specific　ammonia　consumption　rate　of　limited　filamentous　bulking　sludge　was　about　2　times　higher　than　the　one　of　normal　sludge.　On　the　contrary,　the　total　nitrogen　removal　efficiency　was　lower.　Further　analysis　indicated　that　stable　limited　sludge　bulking　could　be　achieved　in　a　good　alternative　anoxic/anaerobic/aerobic　condition　without　too　high　organic　loading.