Patent ID: 6863817

Claim:
An apparatus comprising, a) an aerobic tank or zone; b) an anoxic tank or zone; c) an immersed membrane tank or zone; d) a conduit or passage for mixed liquor to flow from the membrane tank or zone to the anoxic tank or zone; e) a conduit or passage for mixed liquor to flow from the anoxic tank or zone to the aerobic tank or zone; f) a conduit or passage for mixed liquor to flow from the aerobic tank or zone to the membrane tank or zone; g) an inlet for feed to enter into the anoxic tank or zone; h) an outlet for permeate to exit the membrane tank or zone; i) a level sensor for detecting a selected maximum mixed liquor level and a selected minimum mixed liquor level in one of the aerobic tank or zone or the anoxic tank or zone; and j) devices operably connected to the level sensor, wherein the devices are adapted for one or more of (i) stopping and starting permeation, (ii) increasing and decreasing the total air supply provided by an air supply or (iii) altering a regime of cyclic aeration.