The　establishment　of　stable　partial　nitrification　(PN)　is　beneficial　to　promote　the　application　of　anaerobic　ammonium　oxidation,　especially　for　low-ammonium　wastewater.　This　study　demonstrated　an　innovative　approach　for　achieving　PN　through　feeding　low-level　benzethonium　chloride　(BZC).　PN　was　started　and　maintained　for　125　days　after　the　sequential　feeding　of　0.2　and　1　mg/L　BZC　for　50　days.　The　damaged　PN　recovered　rapidly　within　eight　days　by　feeding　2　mg/L　BZC,　and　it　thrived　for　more　than　172　days,　indicating　that　nitriteoxidizing　bacteria　did　not　adapt　to　BZC.　The　removal　of　BZC　changed　from　adsorption　to　degradation　gradually.　Increased　extracellular　polymeric　substances　secretion　and　altered　protein　secondary　structures　explained　sludge　granulation　during　BZC　feeding,　which　may　be　closely　related　to　long-term　stable　maintenance　of　PN.　PICRUSt2　revealed　the　underlying　microbial　mechanisms　in　depth.　Overall,　this　research　proposed　a　novel　scheme　to　achieve　robust　PN　treating　low-ammonium　wastewater　through　feeding　low-level　BZC.