Abstract: In a sewage treatment facility that employs on the liquid side a basin or basins with membrane separators or MBRs for dewatering sludge, filtration is suspended or “relaxed” in short, rapid cycles, with air scour during relaxation, with the result of more efficient stripping of accumulated solids on the membranes, better membrane efficiency and lower overall air scour requirements. Another aspect of the invention is to increase air scour rate during relaxation periods and decrease air scour rate during filtration, whether or not this is in combination with the shorter cycles just described. Another feature of the invention is a liquid valving scheme and mechanism by which liquid/permeate flow can be quickly and smoothly shut off and turned on to transition from relaxation to filtration and vice versa.