Autotrophic　nitrogen　removal　processes　based　on　anammox　are　facing　huge　challenges　of　high　effluent　quality　in　wastewater　treatment.　In　this　study,　a　novel　hybrid　system　of　anammox　coupled　with　heterotrophic　endogenous　metabolisms　was　developed　in　a　single-stage　bioreactor　to　treat　real　domestic　wastewater.　Complete　nitrogen　removal　was　achieved　at　a　low　carbon　to　nitrogen　(C/N)　ratio　of　2.8　and　more　than　95.2%　nitrogen　removal　was　maintained　under　an　extremely　low　C/N　ratio　of　1.9.　The　nitrite　shunt　supplied　by　dual　partial　pathways　(partial　nitritation　and　endogenous　partial　denitratation)　guaranteed　the　anammox　activity　with　a　high　contribution　to　nitrogen　removal　above　60%.　While　endogenous　denitrification　(ED)　and　denitrifying　phosphorus　removal　(DPR)　both　participated　in　nitrate　respiration,　contributing　more　than　28%　and　9%　to　nitrogen　removal,　respectively.　The　coexistence　and　enrichment　of　anammox　bacteria　(Ca.　Brocadia,　0.9%),　glycogen　accumulating　organisms　(Ca.　Competibacter,　6.4%)　and　phosphorus　accumulating　organisms　(Dechloromonas,　3.9%　and　Ca.　Accumulibacter,　0.7%)　contributed　to　the　co-metabolism　of　carbon,　nitrogen　and　phosphorus.　The　functional　genes　encoding　the　above　metabolism　were　highly　correlated　with　the　dominant　strains,　indicating　that　the　multiple　pathways　of　carbon　and　nitrogen　metabolism　supported　the　continuous　supply　of　electrons　required　for　nitrogen　removal.　This　study　puts　forward　a　novel　complete　nitrogen　removal　process　by　successfully　coupling　autotrophic　and　endogenous　heterotrophic　metabolism.　©　2023　Elsevier　B.V.