Improving　contribution　and　nitrogen　removal　efficiency　(NRE)　of　partial　anammox　in　municipal　wastewater　is　a　researching　hotspot.　This　study　developed　an　innovative　PN/A-PD/A　process　with　fixed　biocarriers　in　anaerobic/anoxic　chambers　for　actual　sewage　treatment　in　a　typical　step-feed　reactor　over　390　days.　Two　coupled　pathways　providing　continuous　NO2-　(partial　nitrification　in　oxic　chambers　and　partial　denitrification　in　anaerobic/anoxic　chambers)　for　anammox　were　introduced　to　the　process,　achieving　47%　nitrogen　loss　by　anammox　in　stable　phase.　The　influent　and　effluent　total　inorganic　nitrogen　(TIN)　were　51.3　and　11.0　mg/L,　respectively,　even　with　chemical　oxygen　demand　(COD)/TIN　ratio　of　2.9.　Anammox　activity　improved　from　6.52　to　9.68　mg　NH4+-N/gMLSS/d　and　abundance　on　the　biocarriers　raised　to　3.16　x　10(10)　gene　copies/g　dry　sludge.　Overall,　this　study　confirmed　partial　anammox,　spatially　coupled　with　partial　nitrification　and　partial　denitrification　via　oxic/anoxic　distribution　with　step　feed　mode,　as　an　alternative　for　application　of　mainstream　anammox.