Long-Term Stability of Nitrifying Granules in a Membrane Bioreactor without Hydraulic Selection Pressure

To understand the long-term stability of nitrifying granules in a membrane bioreactor (GMBR), module was submerged an airlift reactor to eliminate hydraulic selection pressure that believed be driving force aerobic granulation. The monitoring results showed structure could remain stable for 305 days GMBR without pressure; however, majority granule actually inactive due mass diffusion limitation. As consequence, active biomass free limitation only inhabited top 60–80 µm layer granules. There dynamic equilibrium between bioflocs and membrane, i.e., 25% attached on surface within last nine backwash cycle synchronization with emergence peak soluble extracellular polymeric substances (sEPS), concentration around 47 mg L−1. Backwash can eventually detach return these bulk solution. However, rate fouling did not change biofloc attachment. In certain sense, investigated this study functioned similar fashion as integrated fixed-film activated sludge thus defeated original purpose development. problem sEPS production should key areas focus future research.