Ferroammonium　oxidation　(anaerobic　ammonium　oxidation　coupled　to　Fe　()　reduction,　Feammox)　refers　to　a　new　type　of　sewage　biological　denitrification　process　under　the　condition　of　anaerobic,　ammonia-nitrogen　oxidation　coupled　with　ferric　iron　reduction.　To　explore　nitrogen　conversion　pathways　and　their　contribution　to　nitrogen　removal　in　Feammox,　the　activated　sludge　was　used　as　seed　sludge　to　acclimate.　After　120　d　of　operation,　the　maximum　conversion　efficiency　of　NH4+-N　reached　53.8%　and　the　maximum　conversion　amount　was　26.9　mg/L,　in　which　Feammox　accounted　for　about　57.7%　and　Anammox　about　42.3%.　In　typical　cycle　operation,　nitrogen　conversion　was　14.74　mg/L　within　0-7　h,　in　which　Anammox　dominated.　During　7-24　h　the　nitrogen　conversion　was　12.16　mg/L,　mainly　by　Feammox.　The　nitrate　removal　through　NDFO　during　the　whole　operation　was　about　5　mg/L.　Based　on　the　correlation　analysis,　NH4+-N　concentration　was　significantly　positively　related　to　Fe()　and　NO2--N　(PFeNO2)3--N　was　negatively　related　to　Fe()　(P　©　All　Right　Reserved.