The　presence　of　nitrite-oxidizing　bacteria　(NOB)　when　treating　low-strength　ammonia　wastewater　was　a　challenge　in　the　application　of　the　PN/A　process.　The　partial　nitrification/ANAMMOX/partial　nitrification/ANAMMOX　(PN/A/PN/A)　process　based　on　multiple　oxidations　of　ammonia　was　proposed　to　solve　this　problem.　The　influence　of　independent　variables　such　as　nitrite　concentration　was　analyzed　based　on　the　response　surface　method　(RSM).　The　model　showed　that　nitrite　concentration　has　an　adverse　impact　on　ammonia　removal　efficiency　and　nitrite　accumulation　rate.　The　model　provided　optimal　parameters　for　the　PN/A/PN/A　process:　the　dissolved　oxygen　concentration　was　0.60　mg/L,　and　the　cycle　duration　was　90　min.　Advanced　nitrogen　removal　was　achieved　by　maintaining　the　nitrite　concentration　below　10.0　mg/L.　The　nitrogen　removal　efficiency　was　81.44　±　4.15　%,　and　the　nitrogen　removal　rate　was　0.18　±　0.02　kg　N/(m3⋅d).　Potential　functions　of　microorganisms　were　analyzed　by　functional　annotation　of　prokaryotic　taxa　(FAPROTAX)　and　the　correlation　network　analysis　was　performed.　©　2022　Elsevier　Ltd