The　main　challenge　for　achieving　the　simultaneous　nitritation,　anammox　and　denitrification　(SNAD)　process　is　to　optimize　the　concentrations　of　nitrite　and　dissolved　oxygen　(DO).　This　study　explored　the　performance　of　SNAD　biofilm　reactor　under　three　operational　strategies.　At　Stage　1,　2　and　3,　the　average　concentrations　of　DO　were　0.7,　2.7　and　5.2　mg/L,　respectively.　The　peak　concentrations　of　NO2–-N　in　the　sequencing　batch　reactor　(SBR)　cycle　were　5.3,　6.0　and　2.7　mg/L,　respectively.　The　average　removal　rates　of　total　inorganic　nitrogen　(TIN)　were　0.30,　0.42　and　0.22　kg　N/m3/d,　respectively.　Protein　(PN)　was　the　dominant　extracellular　polymeric　substance　(EPS)　content　on　the　SNAD　biofilm.　The　PN　concentration　remained　stable　while　the　polysaccharide　(PS)　concentration　changed　rapidly　under　different　operational　strategies.　High-throughput　sequencing　analysis　indicated　that　high　DO　and　long　aeration　period　condition　could　lead　to　a　slight　decrease　in　the　abundances　of　denitrifying　bacteria　and　anammox　bacteria.　©　2020　Elsevier　Ltd