The　stringent　effluent　quality　standards　in　wastewater　treatment　plants　(WWTPs)　can　effectively　mitigate　environmental　issues　such　as　eutrophication　by　reducing　the　discharge　of　nutrients　into　water　environments.　However,　the　current　wastewater　treatment　process　often　struggles　to　achieve　advanced　nutrient　removal　while　also　saving　energy　and　reducing　carbon　consumption.　The　first　full-scale　anaerobic/aerobic/anoxic　(AOA)　system　was　established　with　a　wastewater　treatment　scale　of　40,000　m3/d.　Over　one　year　of　operation,　the　average　TN　and　TP　concentration　in　the　effluent　of　7.53　+/-　0.81　and　0.37　+/-　0.05　mg/L　was　achieved　in　low　TN/COD　(C/　N)　ratio　(average　5)　wastewater　treatment.　The　post-anoxic　zones　fully　utilized　the　internal　carbon　source　stored　in　pre-anaerobic　zones,　removing　41.29　%　of　TN　and　36.25　%　of　TP.　Intracellular　glycogen　(Gly)　and　proteins　in　extracellular　polymeric　substances　(EPS)　served　as　potential　drivers　for　post-anoxic　denitrification　and　phosphorus　uptake.　The　sludge　fermentation　process　was　enhanced　by　the　long　anoxic　hydraulic　retention　time　(HRT)　of　the　AOA　system.　The　relative　abundance　of　fermentative　bacteria　was　31.66　-　55.83　%,　and　their　fermentation　metabolites　can　provide　additional　substrates　and　energy　for　nutrient　removal.　The　development　and　utilization　of　internal　carbon　sources　in　the　AOA　system　benefited　from　reducing　excess　sludge　production,　energy　conservation,　and　advanced　nutrient　removal　under　carbon-limited.　The　successful　full-scale　validation　of　the　AOA　process　provided　a　potentially　transformative　technology　with　wide　applicability　to　WWTPs.