In　this　study,　an　innovative　partial　nitrification-anammox　(PN/A)　and　endogenous　partial　denitrificationanammox　(EPD/A)　process　was　developed　in　a　single-stage　integrated　fixed　film　activated　sludge　sequencing　batch　reactor　(IFAS-SBR)　treating　real　municipal　wastewater　with　C/N　ratio　below　3.2.　Enhanced　efficiency　of　total　nitrogen　(TN)　removal　reached　90.1%　with　low　HRT　of　12　h　and　DO　of　0.4　+/-　0.1　mg/L.　Detailed　nitrogen　removal　mechanism　analysis　of　typical　cycle　revealed　that　89.9%　of　TN　was　eliminated　through　anammox　pathway.　Anammox　bacteria　(Candidatus　Brocadia)　and　endogenous　denitrifying　bacteria　(Candidatus　Competibacter)　were　abundant　both　in　biofilms　and　suspended　sludge,　meanwhile　ammonium-oxidizing　bacteria　has　outcompeted　nitrite-oxidizing　bacteria,　which　all　favored　the　synergistic　effect　of　anammox　with　PN　and　EPD　and　contributed　to　the　improvement　of　nitrogen　removal.　Overall,　the　above　results　confirmed　that　combined　PN/A　and　EPD/A　process　is　a　reliable　and　efficient　alternative　for　mainstream　anammox　process.