In　order　to　study　the　effect　of　different　volumetric　exchange　rates　(VER)　on　the　granulation　and　stable　operation　of　SNAD　sludge,　two　lab-scale　SBR　reactors,　with　a　37.5%　VER　(R1)　and　75%　VER　(R2),　were　comparably　analyzed.　Experimental　results　demonstrated　that　the　granulation　of　R1　could　be　achieved　in　36　days,　was　12　days　faster　than　R2.　Meanwhile,　a　relatively　lower　sludge　loss　rate　of　R1　was　obtained.　The　nitrogen　removal　rate　(RNR),　RAO　and　RAN　in　R1　were　0.356　g·L-1·d-1,　0.113　0　and　0.080　9　g·g-1·d-1,　respectively;　while　that　of　R2　was　0.248　g·L-1·d-1,0.093　6　and　0.070　5　g·g-1·d-1,　respectively.　This　confirmed　that　a　lower　VER　reduced　the　loss　of　floc　sludge,　and　further　declined　the　granulation　period.　Moreover,　a　lower　VER　not　only　enhanced　the　activity　of　ammonia-oxidizing　and　anaerobic　ammonia-oxidizing　bacteria,　but　also　suppressed　nitrite-oxidizing　bacteria,　was　benefit　for　a　stable　and　efficient　removal　performance　of　the　SNAD　granular　sludge.　©　2017,　Editorial　Board　of　Journal　of　Harbin　Institute　of　Technology.　All　right　reserved.