In　anaerobic　ammonium　oxidation　(Anammox)　process,　a　harsh　ratio　of　nitrite　to　ammonia　in　influent　was　demanded,　and　the　max　nitrogen　removal　efficiency　could　only　achieve　to　89%,　both　of　which　limited　the　development　of　Anammox.　The　aim　of　this　work　was　to　study　the　nitrate　removal　by　organotrophic　anaerobic　ammonium　oxidizing　bacteria　(AAOB)　with　C2/C3　fatty　acid　in　upflow　anaerobic　sludge　blanket　(UASB)　reactors.　In　this　study,　organotrophic　AAOB　was　successfully　enriched　by　adding　acetate　and　propionate　with　the　total　organic　carbon　to　nitrogen　(TOC/N)　ratio　of　0.1.　In　the　condition　of　low　substrate,　the　TN　removal　efficiency　reached　90%,　with　the　effluent　TN　of　around　11.8　mg　L　1.　After　the　addition　of　acetate　and　propionate,　the　predominant　species　in　Anammox　granular　sludge　transformed　to　Candidatus　Jettenia　that　belonging　to　organotrophic　AAOB　from　the　Candidatus　Kuenenia　relating　to　general　AAOB.　(C)　2015　Elsevier　Ltd.　All　rights　reserved.