Immersed membranes activated sludge process applied to the treatment of municipal wastewater

An immersed membrane activated sludge process has been evaluated at pilot scale by Anjou Recherche. This process represents a new generation of hybrid techniques, which aims at coupling biological treatment and membrane filtration functions, in a configuration adapted to the treatment of municipal wastewater. The process was evaluated under extended aeration conditions, but with concentrations of biomass of between 15 to 25 gMLSS/l, which corresponded to volumetric loadings of between 1.2 to 2.3 kg COD/m3/d. Under these conditions, COD and TKN removal were better than 96% and 95%, respectively. The membrane ensured total removal of suspended solids and produced treated water of excellent bacteriological quality. The sludge production stabilized at 0.20 gDS/kg COD removed. The membrane flux was stable for all conditions tested.