High　nutrients　removal　above　90%　from　carbon-limited　municipal　sewage　was　obtained　without　adding　external　carbon　source.　Achieving　nitritation　was　a　prerequisite　to　improve　nutrients　removal.　Denitrifying　phosphorus　(P)　removal　using　nitrite　as　electron　acceptor　was　the　key　pathway　in　anoxic　zone,　where　nitrogen　removal　reached　above　60%　and　average　denitrifying　P　removal　was　88%.　Simultaneous　nitritation/denitritation　and　anaerobic　ammonia　oxidation　(anammox)　possibly　contributed　to　nitrogen　removal　of　26-36%　in　aerobic　zone.　Quantitative　PCR　assays　presented　that　the　abundance　of　anammox　bacteria　under　nitritation　was　more　than　that　under　complete　nitrification.　The　largest　amount　of　anammox　bacteria　was　1.32　x　10(6)　copies/g　VSS,　about　5.6　times　increase　over　a　period　of　255　days.　Nitrite　concentration　of　17　mg/L　in　aerobic　zone　inhibited　anammox　bacteria.　Quantitative　results　suggested　possible　occurrence　of　anammox.　Based　on　performance　of　nitritation,　combining　heterotrophic　denitrification　with　autotrophic　nitrogen　removal　is　an　effective　strategy　to　improve　nutrients　removal　from　carbon-limited　wastewater.　(C)　2014　Elsevier　Ltd.　All　rights　reserved.