While　sulfur-driven　autotrophic　denitrification　(SDAD)　occurring　in　the　anoxic　reactor　of　the　sulfate　reduction,　autotrophic　denitrification　and　nitrification　integrated　(SANI)　system　has　been　regarded　as　the　main　nitrogen　removal　bioprocess,　little　is　known　about　the　accompanying　Anammox　bacteria　whose　presence　is　made　possible　by　the　co-existence　of　NH4+　and　NO2−.　Therefore,　this　work　firstly　developed　an　integrated　SDAD-Anammox　model　to　describe　the　interactions　between　sulfur-oxidizing　bacteria　and　Anammox　bacteria.　The　model　was　subsequently　used　to　explore　the　impacts　of　influent　conditions　on　the　reactor　performance　and　microbial　community　structure　of　the　anoxic　reactor.　The　results　revealed　that　at　a　relatively　low　ratio　of　©　2022　Elsevier　Ltd