The　feasibility　of　using　a　two-stage　autotrophic　nitrogen　removal　process　to　treat　sewage　was　examined　in　this　study.　The　obtained　results　showed　that　total　nitrogen　(TN)　could　be　efficiently　removed　by　88.38%　when　influent　TN　and　chemical　oxygen　demand　(COD)　were　45.87　and　44.40　mg/L,　respectively.　In　the　first　stage,　nitritation　was　instantly　achieved　by　the　bioaugmentation　strategy,　and　can　be　maintained　under　limited　oxygen　condition　(below　0.2　mg/L).　The　ratio　of　nitrite　to　ammonium　in　the　effluent　of　the　nitritation　reactor　can　be　controlled　at　approximate　1.0　by　adjusting　aeration　rate.　In　the　second　stage,　anammox　was　realized　in　the　upflow　anaerobic　sludge　blanket　(UASB)　reactor,　where　the　total　nitrogen　removal　rate　was　0.40　kg　N　m(-3)　d(-1)　under　limited-substrate　condition.　Therefore,　the　organic　matter　in　sewage　can　be　firstly　concentrated　in　biomass　which　could　generate　biogas　(energy).　Then,　nitrogen　in　sewage　could　be　removed　in　a　two-stage　autotrophic　nitrogen　removal　process.　(C)　2011　Elsevier　Ltd.　All　rights　reserved.