The objective of the study was to optimize the hydraulic operating conditions and the cleaning strategy of a novel flat sheet MBR filtration system developed by A3 water solutions. Four areas were focused on in particular: the optimization of the filtration operating conditions; the impact of peak flows oil the membrane performances; the impact of a double-deck configuration and the testing of chemical cleaning products as alternatives to chlorine. The A3 water Solutions technology was operated for 11 months under typical biological operating conditions (MLSS = 9 gSS/L; SRT = 28.6 days) for MBR systems. The optimum net flux of 26.4 L/h m(2) at 20 degrees C gave a stable permeability around 500-600 L/h m(2) bar at 20 degrees C with filtration/relaxation cycles of 8 min/2 min and an air flow rate of 0.34 Nm(3)/h m(2). The optimization of the cleaning strategy enabled to operate with a net flux of 25.5 L/h m(2) at 20 degrees C at a lower membrane air flow rate of 0.21 Nm(3)/h m(2) and to recover the permeability after some bio-fouling. Regular peak flows did not affect the membrane performances. The double-deck configuration did not influence the fouling characteristics of each module.