An　integrated　partial　nitrification,　sludge　fermentation　and　denitrification　process　in　a　sequencing　batch　reactor　(PNSFD-SBR),　was　developed　to　enhance　nitrogen　removal　from　domestic　wastewater　with　low　C/N　(i.e.　SCOD/TN)　between　2　to　3　and　to　reutilize/reduce　external　waste　activated　sludge　(WAS).　Average　ammonium　removal　efficiency　of　95.9%,　total　nitrogen　removal　efficiency　of　93.5%,　and　external　WAS　reduction　rate　of　21.6%　was　achieved　during　long-term　experiment　at　30　+/-　1　degrees　C.　Real-time　pH-DO　(dissolved　oxygen)　monitor　and　control　played　an　important　role　in　the　PNSFD　achievement.　A　batch　test　indicated　that　micro-aeration　(less　than　1　mg/L)　sustained　partial　nitrification,　which　further　facilitated　subsequent　sludge　fermentation　and　denitrification　processes.　Moreover,　Illumina　MiSeq　analysis　demonstrated　the　predominant　bacteria　were　Rhodocyclaceae,　Anaerolineaceae　and　Saprospiraceae　on　family　level　and　they　were　key　to　partial　nitrification,　denitrification　and　sludge　fermentation,　by　which　the　feasibility　of　PNSFD　process　to　achieve　simultaneous　nitrogen　removal　and　external　WAS　reutilization/reduction　was　verified.　(C)　2016　Published　by　Elsevier　B.V.