Since　unsustainable　partial　nitrification　prone　to　unstable　nitrogen　removal　rates,　cultivation　and　enrichment　of　AnAOB,　further　improve　autotrophic　nitrogen　removal　contribution　have　been　challenges　in　the　mainstream　anammox　process.　This　study　proposed　a　new　strategy　to　enrich　AnAOB　motivated　by　endogenous　partial　denitrification　(EPD)　in　total　floc　sludge　system　through　the　AOA　process　with　sustainable　nitrification.　The　results　showed　that　in　the　presence　of　NH4+　and　NO3–　at　the　anoxic　stage　of　N-EPDA,　Ca.　Brocadia　was　enriched　(0.005%→0.92%)　in　floc　sludge　via　internal　carbon　source　metabolism　of　EPD.　The　C/N　and　temperature　of　N-EPDA　were　also　optimized　to　achieve　higher　activities　of　EPD　and　anammox.　The　N-EPDA　was　operated　at　low　C/N　ratio　(3.1)　with　anammox　nitrogen　removal　contribution　of　78%　during　the　anoxic　stage,　Eff.TIN　of　8.3　mg/L　and　NRE　of　83.5%　during　phase　III,　achieved　efficient　autotrophic　nitrogen　removal　and　AnAOB　enrichment　in　the　absence　of　partial　nitrification.　©　2023　Elsevier　Ltd