Nitritation　and　denitrifying　P　removal　under　mode　of　nitritation　and　nitrification　was　investigated　in　continuous　MUCT　process　treating　domestic　wastewater.　Nitritation　was　established　through　short　hydraulic　retention　time　to　6　h　and　low　dissolved　oxygen　concentration　of　0.3-0.5　mg/L.　Nitritation　was　stabilized　for　95　days　with　average　nitrite　accumulation　ratio　over　90%.　Ammonia　and　total　nitrogen　removal　under　nitritation　reached　99%　and　83%,　respectively,　much　better　than　complete　nitrification.　Real-time　quantitative　PCR　assays　presented　that　cell　numbers　and　percentages　of　ammonia　oxidizing　bacteria　(AOB)　population　had　a　clear　correlation　with　nitrite　accumulation　ratios.　The　highest　percentage　of　AOB　was　13%　of　total　bacterial　population.　P　removal　was　mainly　completed　by　denitrifying　P　removal　of　about　90%　occurring　in　anoxic　zone.　The　P　removal　efficiency　under　nitritation　was　30%　higher　than　that　under　complete　nitrification.　Denitrifying　P　removal　under　nitritation　was　highly　beneficial　to　the　treatment　of　wastewater　with　limiting　carbon　source.　(C)　2013　Elsevier　Ltd.　All　rights　reserved.