Characteristics of nitrogen removal in aerobic granular sludge membrane bioreactor

An aerobic granular sludge membrane bioreactor(GMBR) had been stably operated for 71 days, and it showed good organics removal and simultaneous nitrification and denitrification (SND) performances. TOC, ammonium and total nitrogen removal efficiencies of GMBR remained 84.7% - 91.9%, 85.4% - 99.7% and 41.7% - 78.4% respectively as influent TOC were 56.8 - 132.6 mg/L and ammonium nitrogen were 28.1 - 38.4 mg/L. Moreover, further batch tests of different size sludge revealed that floclike sludge nearly had not SND ability, the SND performances of GMBR was mostly come from granular sludge, and denitrification rate and total nitrogen removal efficiencies under aerobic condition increased with sludge size increased. Analyzing the morphology and section characteristics of granular sludge under scan electron microscope, the SND process was also described.