Anaerobic　ammonia　oxidation　coupled　to　Fe　(III)　reduction　(Feammox)　plays　an　important　role　in　the　natural　nitrogen　cycle.　However,　for　its　application　in　wastewater　treatment　process,　the　source　of　iron　is　a　major　limitation.　In　this　study,　Feammox　process　was　successfully　achieved　without　external　iron　addition　using　sponge　iron　biofilm.　The　products　of　Feammox　process,　nitrate　and　Fe　(II),　provided　substrates　for　nitrate　dependent　ferrous　oxidation　(NDFO).　Therefore,　nitrogen　removal　and　Fe　(II)/Fe　(III)　cycle　were　achieved　in　reactor　and　nitrogen　removal　efficiency　by　Feammox　and　NDFO　pathways　was　up　to　58.4　%.　The　X-ray　diffraction　indicated　the　sludge　contained　magnetite　and　lepidocrocite,　which　provided　Fe　(III)　for　the　occurrence　of　Feammox.　Microorganisms　related　to　Feammox　process　were　dominated　by　Geothrix.　It　was　found　Feammox　activity　was　similar　at　pH　of　8　and　7,　while　inhibited　at　pH　of　6,　which　was　caused　by　the　decrease　of　Feammox　bacteria.　And　Feammox　activity　decreased　with　the　decrease　of　temperature,　in　which　the　ammonia　removal　rate　was　2　times　faster　at　30　degrees　C　than　at　10　degrees　C.　Under　micro-oxygen　aeration,　the　ammonia　removal　rate　improved　and　Feammox　and　NDFO　processes　still　played　roles　in　system,　nevertheless,　under　high　dissolved　oxygen　condition,　Feammox　bacteria-Geothrix　and　NDFO　bacteria　Thiobacillus　would　be　gradually　eliminated　from　the　system.