Abstract: Submerged gas diffuser assemblies configured to aerate liquid suspensions in reservoirs or deep shafts with enhanced aeration contact patterns and adjustable aeration rates. Aeration contact patterns and rates are varied by the adjusting the spatial configuration of gas permeable membranes, altering the fluid flow patterns around the membranes, manipulating trans-membrane pressures across membranes, varying the sequence of aeration of liquid within the fluid flow patterns, expanding the membrane surface area, and/or by selectively occluding certain portions of membrane surface area of the membrane assemblies. The membrane assemblies are designed to prevent, control, or mitigate membrane fouling and hydro lockup.