Anammox　is　widely　considered　as　the　most　cost-effective　and　sustainable　process　for　ni-trogen　removal.However,how　to　achieve　the　enrichment　of　anammox　biomass　remains　a　challenge　for　its　large-scale　application,especially　in　mainstream　wastewater　treatment.In　this　study,the　feasibility　of　enrichment　of　anammox　biomass　was　explored　through　the　realization　of　partial　denitrification　and　the　addition　of　bio-carriers.By　using　ordinary　acti-vated　sludge,a　sequencing　batch　reactor(SBR)followed　by　an　up-flow　anaerobic　sludge　bed(UASB)was　operated　at　25±2℃　for　214　days.The　long-term　operation　was　divided　into　five　phases,in　which　SBR　and　UASB　were　started-up　in　Phases　Ⅰ　and　Ⅱ,respectively.By　eliminat-ing　oxygen　and　adjusting　the　inflow　ratios　in　Phases　Ⅲ-Ⅴ,advanced　nitrogen　removal　was　achieved　with　the　effluent　total　nitrogen　being　4.7　mg/L　and　the　nitrogen　removal　efficiency　being　90.5％in　Phase　V.Both　in-situ　and　ex-situ　activity　tests　demonstrated　the　occurrence　of　partial　denitrification　and　anammox.Moreover,16S　rRNA　high-throughput　sequencing　analysis　revealed　that　Candidatus　Brocadia　was　enriched　from　below　the　detection　limit　to　in　biofilms(0.4％in　SBR,2.2％in　UASB)and　the　floc　sludge(0.2％in　SBR,1.3％in　UASB),while　Thauera　was　mainly　detected　in　the　floc　sludge(8.1％in　SBR,8.8％in　UASB),which　might　play　a　key　role　in　partial　denitrification.Overall,this　study　provides　a　novel　strategy　to　en-rich　anammox　biomass　driven　by　rapid　achievement　of　partial　denitrification　through　the　addition　of　bio-carriers,which　will　improve　large-scale　application　of　anammox　processes　in　mainstream　wastewater　treatment.