Acidophilic　partial　nitrification　(a-PN)　is　a　promising　short-flow　nitrogen　conversion　biotechnology,　but　achieving　a　rapid　startup　remains　a　significant　challenge.　This　study　explored　strategies　for　starting　up　a-PN　in　real　municipal　wastewater　treatment　using　sequencing　batch　reactors　(SBRs).　The　influent　alkalinity-to-NH4+　molar　ratio　was　maintained　at　0.5–0.6　in　the　control　reactor　(SBRa),　while　other　reactors　were　supplemented　with　sodium　formate　(150　mg　COD/L,　SBRb),　hydroxylamine　(5　mg/L,　SBRc),　and　sludge　alkaline　fermentation　liquid　(NH4+-N=227.97±7.08　mg/L,　COD=2463.98±125.17　mg/L,　SBRd).　Results　indicated　that　the　system　using　the　composite　strategy　with　sodium　formate　addition　achieved　a　93.7　%　nitrite　accumulation　ratio　(NAR)　within　just　4　days.　Furthermore,　stable　a-PN　performance　was　maintained　in　the　systems　without　external　substrate　addition　with　pH　ranging　from　5.7　to　7.4.　The　established　a-PN　systems　demonstrated　robust　performance,　maintained　a　high　NAR　of　92.84　%-98.84　%,　even　under　the　intense　impact　of　traditional　nitrification　biomass　for　13　consecutive　days.　Although　the　relative　abundances　of　Nitrosomonas　and　Nitrospira　temporarily　increased,　traditional　ammonia　oxidizing　bacteria　and　nitrite　oxidizing　bacteria　were　completely　eliminated,　falling　to　undetectable　levels　after　long-term　operation.　Notably,　amo　and　hao　genes　exhibited　opposite　trends:　amo　decreased　significantly　from　356　reads　to　22–46　reads,　while　hao　substantially　increased　by　186.6　%-613.1　%,　from　626　reads　to　1168–2838　reads.　This　suggests　that　hao　may　play　a　more　crucial　functional　role　in　the　a-PN　process,　and　unidentified　nitrifying　communities　may　be　driving　acidophilic　partial　nitrification.　Overall,　our　study　advances　the　understanding　of　rapid　startup　strategies　of　a-PN　and　provides　novel　perspectives　on　the　microbial　structure　and　functional　genes　involved　in　a-PN　system.　©　2024　Elsevier　Ltd