Abstract: A membrane filtration apparatus located in a filtration chamber has a number of membranes and an associated support structure having a plurality of input passages and output passages. Wastewater is delivered to the input passages at one side of the membranes and the output passages receive cleaned water at the other side of the membranes after it has passed through a membrane. Each of the input passages is open at top and bottom to the filtration chamber interior, but substantially closed laterally. In a method and apparatus for cleaning the filtration apparatus, gas bubbles are discharged into the wastewater below a first subset of the input passages to cause airlift induced circulation of the wastewater up through the first subset, the flow being directed across and down through a second subset of the input passages.

Abstract: A method and apparatus for cleaning a membrane bioreactor having a stack of generally vertically oriented membrane filter plates mounted in a filtration chamber containing wastewater. In a first cleaning phase, air is supplied to a first discharge zone under the stack to discharge gas bubbles into the wastewater at the bottom of the stack so that the gas bubbles rise upwardly through passages between the filter plates to scour surfaces of the membranes bounding the passages. In a second cleaning phase, gas is supplied to a second discharge zone at the bottom of the stack and surrounding it to cause air lift induced circulation of the wastewater up around the sides of the stack and downwardly through the passages between the filter plates to eject accumulated fibrous material from the passages and to scour surfaces of the membranes bounding the passages.