Introducing　carbon　sources　to　achieve　nitrogen　removal　from　mature　landfill　leachate　not　only　increases　the　costs　and　carbon　emissions　but　also　inhibits　the　activity　of　autotrophic　bacteria.　Thus,　this　study　constructed　a　double　anammox　system　that　combines　partial　nitrification-anammox　(PNA)　and　endogenous　partial　denitrification-anammox　(EPDA)　within　an　integrated　fixed-film　activated　sludge　(IFAS)　reactor.　In　this　system,　PNA　primarily　contributes　to　nitrogen　removal　pathways,　achieving　a　nitrite　accumulation　rate　of　98.23%.　The　production　of　extracellular　polymer　substances　(EPS)　in　the　IFAS　reactor　is　stimulated　by　introducing　co-fermentation　liquid.　Through　the　utilization　of　EPS,　the　system　effectively　achieves　EPDA　with　the　nitrite　transformation　rate　of　97.20%.　Under　the　intermittent　aeration　operation　strategy,　EPDA　combined　with　PNA　and　anammox　in　the　oxic　and　anoxic　stages　enhanced　the　nitrogen　removal　efficiency　of　the　system　to　99.70　±　0.12%.　The　functional　genus　Candidatus　kuenenia　became　enriched　in　biofilm　sludge,　while　Thauera　and　Nitrosomonas　predominated　in　floc　sludge.　©　2023　Elsevier　Ltd