Abstract: An apparatus for filtering a liquid in a tank has a plurality of elements and a frame for holding the elements while they are immersed in the liquid. The elements have a plurality of hollow fibre membranes attached to and suspended between an upper header and a lower header. The membranes are in fluid communication with one or more permeate channels in one or more of the headers. Releasable attachments between the headers and the frame allow the frame to releasably hold the elements by their headers. The size and configuration of the frame determines the positions of the upper and lower headers of each element relative to each other. Connections between the permeate channels and one or more permeate collection tubes attached to the frame are releasable and resealable connections which are made or broken automatically by the movements involved in inserting or removing an element into or out of the frame.

Abstract: A curved hollow fiber membrane comprises a support and a film. The support is curved before being coated with the film. The membrane may be used, for example, in a filtration module.

Abstract: An aerator for immersed filtering membranes has an aerator shell with openings for discharging bubbles from its upper surface and a shape capable of temporarily containing a volume of air in fluid communication with the openings. The shell is open to tank water below it and located so that discharged bubbles will rise through an assembly of the filtering membranes. The shell may be wholly or partially made of parts of the assemblies of filtering membranes. A supply of air is provided to the air space in the aerators alternating between a high flow rate and a low flow rate in short cycles of between about 10 seconds and 100 seconds. A filtration system has an inlet for adding substrate and an outlet for retentate are located so as to create a horizontal flow of substrate through the tank. Membrane assemblies are located within the horizontal flow of substrate. Aerators as described above are provided and operated as described above.

Abstract: An apparatus is described for withdrawing filtered permeate from a substrate contained in a reservoir at ambient pressure. The apparatus includes a plurality of membrane assemblies. Each assembly has a plurality of hollow fiber filtering membranes, immersed in the reservoir, at least one permeating header with the membranes sealingly secured therein, and a permeate collector to collect the permeate sealingly connected to the at least one permeating header and in fluid communication with lumens of the membranes. The membranes of each assembly extend generally vertically upwards from a first header during permeation. One or more sources of suction are provided in fluid communication with the lumens of the membranes of each assembly through the permeate collectors and apply sufficient suction to withdraw permeate from the lumens of the membranes. An aeration system for discharging bubbles assists in keeping the membranes clean.

Abstract: Modules of ultrafiltration or microfiltration membranes are arranged in a tank open to the atmosphere to substantially cover the cross sectional area of the tank. A filtration cycle has permeation steps and deconcentration steps. During permeation, supply of feed substantially equals feed removed and little if any aeration is used. During deconcentration, aeration with scouring bubbles is provided with one or both of backwashing and feed flushing. In feed flushing, feed water is supplied to the tank from below the modules. Excess tank water created during deconcentration flows generally upwards through the modules and out through a retentate outlet or overflow at the top of the tank.

Abstract: Apparatus incorporating potted hollow fibre membranes has a solid mass of potting material having a first face, a plurality of hollow fibre membranes sealed in the potting material. Portions of the membranes adjacent open ends of the membranes protrude from the first face. The potting material extends to and adhesively secures to the inner periphery of a permeate collection means to form a permeate collection zone. The permeate collection means may have walls enclosing a plenum adapted to receive a gas. The apparatus may have an air tube passing through the potting material and having an end in communication with a plenum or manifold adapted to receive a gas.

Abstract: An aeration system for a submerged membrane module has a set of aerators connected to an air blower, valves and a controller adapted to alternately provide a higher rate or air flow and a lower rate of air flow in repeated cycles. In an embodiment, the air blower, valves and controller, simultaneously provide the alternating air flow to two or more sets of aerators such that the total air flow is constant, allowing the blower to be operated at a constant speed. In another embodiment, the repeated cycles are of short duration. Transient flow conditions result in the tank water which helps avoid dead spaces and assists in agitating the membranes.

Abstract: An apparatus to transfer gas to or from a liquid has a flexible and oxygen permeable but liquid water impermeable membrane, a flexible and gas permeable spacer, an inlet conduit, an outlet conduit and a non-rigid restrain system. When used for treating wastewater, an aerobic biofilm is culture adjacent the planar elements, an anoxic biofilm is cultivated adjacent the aerobic biofilm and the wastewater is maintained in an anaerobic state. A first reactor for treating wastewater has an anaerobic section, a plurality of gas transfer membrane modules, and an aerobic section. A biofilm is cultivated on the surface of the gas transfer membranes in fluid communication with the anaerobic section. Biological reduction of COD, BOD, nitrogen and phosphorous are achieved. In a second reactor, phosphorous is also removed chemically in a precipitation branch.

Abstract: An apparatus for filtering a liquid in a tank has a plurality of elements and a frame for holding the elements while they are immersed in the liquid. The elements have a plurality of hollow fibre membranes attached to and suspended between an upper header and a lower header. The membranes are in fluid communication with one or more permeate channels in one or more of the headers. Releasable attachments between the headers and the frame allow the frame to releasably hold the elements by their headers. The size and configuration of the frame determines the positions of the upper and lower headers of each element relative to each other. Connections between the permeate channels and one or more permeate collection tubes attached to the frame are releasable and resealable connections which are made or broken automatically by the movements involved in inserting or removing an element into or out of the frame.

Abstract: A membrane filtration device has a multiplicity of hollow fiber membranes, or fibers, unconfined in a shell of a module; a first header and a second header disposed in vertically spaced-apart relationship; said first header and said second header having opposed ends of each fiber sealingly secured therein, all open ends of said fibers open to a permeate-discharging face of at least one header; permeate collection means to collect said permeate, sealingly connected in open fluid communication with a permeate-discharging face of at least one of said headers; means to withdraw said permeate; said fibers, said headers and said permeate collection means together forming an integrated combination wherein said fibers are essentially vertically disposed and ends of individual fibers are potted in closely spaced-apart relationship in cured resin; with opposed faces at a fixed distance; each of said fibers having a length from 0.1% to less than 5% greater.

Abstract: An apparatus for filtering a liquid in a tank has a plurality of elements and a frame for holding the elements while they are immersed in the liquid. The elements have a plurality of hollow fibre membranes attached to and suspended between an upper header and a lower header. The membranes are in fluid communication with one or more permeate channels in one or more of the headers. Releasable attachments between the headers and the frame allow the frame to releasably hold the elements by their headers. The size and configuration of the frame determines the positions of the upper and lower headers of each element relative to each other. Connections between the permeate channels and one or more permeate collection tubes attached to the frame are releasable and resealable connections which are made or broken automatically by the movements involved in inserting or removing an element into or out of the frame.

Abstract: A method of potting a plurality of hollow fiber membranes into a mass of solidified potting liquid is described. Open ends of a plurality of hollow fiber membranes are enclosed in a first material held in a container which may be a part of a permeate collection means, for example, a permeate pan or header enclosure. A potting liquid is flowed into the container over the first material. The potting liquid surrounds each hollow fiber membrane and then becomes a solid mass that provides a fluid-tight seal to the outside of the hollow fiber membranes. The first material prevents the potting liquid or solid mass from closing the ends of the membranes. The first material is later removed from the ends of the hollow fiber membranes.

Abstract: A membrane filtration device has a multiplicity of hollow fiber membranes, or fibers, unconfined in a shell of a module; a first header and a second header disposed in vertically spaced-apart relationship; said first header and said second header having opposed ends of each fiber sealingly secured therein, all open ends of said fibers open to a permeate-discharging face of at least one header; permeate collection means to collect said permeate, sealingly connected in open fluid communication with a permeate-discharging face of at least one of said headers; means to withdraw said permeate; said fibers, said headers and said permeate collection means together forming an integrated combination wherein said fibers are essentially vertically disposed and ends of individual fibers are potted in closely spaced-apart relationship in cured resin; with opposed faces at a fixed distance; each of said fibers having a length from 0.1% to less than 5% greater.

Abstract: An aeration system for a submerged membrane module has a set of aerators connected to an air blower, valves and a controller adapted to alternately provide a higher rate or air flow and a lower rate of air flow in repeated cycles. In an embodiment, the air blower, valves and controller, simultaneously provide the alternating air flow to two or more sets of aerators such that the total air flow is constant, allowing the blower to be operated at a constant speed. In another embodiment, the repeated cycles are of short duration. Transient flow conditions result in the tank water which helps avoid dead spaces and assists in agitating the membranes.

Abstract: An apparatus to transfer gas to or from a liquid has a flexible and oxygen permeable but liquid water impermeable membrane, a flexible and gas permeable spacer, an inlet conduit, an outlet conduit and a non-rigid restraint system. When used for treating wastewater, an aerobic biofilm is cultured adjacent the planar elements, an anoxic biofilm is cultivated adjacent the aerobic biofilm and the wastewater is maintained in an anaerobic state. A first reactor for treating wastewater has an anaerobic section, a plurality of gas transfer membrane modules, and an aerobic section. A biofilm is cultivated on the surface of the gas transfer membranes in fluid communication with the anaerobic section. Biological reduction of COD, BOD, nitrogen and phosphorous are achieved. In a second reactor, phosphorous is also removed chemically in a precipitation branch.

Abstract: An element for use in ultrafiltration or microfiltration of potable water has a large number of small diameter hollow fibre membranes attached between two headers. Side plates attached to the sides of the headers define vertical flow channels containing the membranes. The elements may be placed side by side and stacked on top of each other to form cassettes having continuous vertical flow channels through the entire cassette. The membrane modules or cassettes may be arranged to cover a substantial part of the cross sectional area of an open tank. Tank water may flow upwards or downwards through the flow channels. A tank may be deconcentrated by at least partially emptying and refilling the tank with fresh water while permeation continues. Excess tank water created during deconcentration may flow generally upwards through the modules and out through a retentate outlet or overflow at the top of the tank.

Abstract: One or more aerators move below an area of an assembly of immersed filtering membranes to be aerated. The movement can take various forms including the sweep of a pendulum. Positions in the assembly of membranes may be alternately aerated for a period of time and then not aerated for a period of time.

Abstract: Limitation of the number of cassettes in an assembly currently used for the production of permeate is obviated by grouping plural cassettes into racks one or more of which may be isolated while permeate production from the remaining racks is uninterrupted. Ancillary functions such as back-pulsing, chemical cleaning and testing for defects in membranes (“integrity testing”) in one or more racks may proceed while production of permeate continues. The number of racks in a bank is determined by the period of the overall filtration cycle, typically 15 min, in which filtration period the ancillary period is a minor portion, typically 30 sec. The racks make it possible to use automatic on/off valves which open and close quicker than larger ones. The resulting saving in time, energy, and equipment costs, which when back-pulsing with permeate is surprisingly economical, is even greater when a chemical cleaning solution is to be used.

Abstract: A vertical skein of “fibers”, opposed terminal portions of which are held in headers unconfined in a modular shell, is aerated with a gas-distribution means which produces a mass of bubbles serving the function of a scrub-brash for the outer surfaces of the fibers. The membrane device is surprisingly effective with relatively little cleansing gas, the specific flux through the membranes reaching an essentially constant relatively high value because the vertical deployment of fibers allows bubbles to rise upwards along the outer surfaces of the fibers. Further, bubbles flowing along the outer surfaces of the fibers make the fibers surprisingly resistant to being fouled by build-up of deposits of inanimate particles or microorganisms in the substrate provided that the length of each fiber is only slightly greater than the direct center-to-center distance between opposed faces of the headers, preferably in the range from at least 0.1% to about 5% greater.

Abstract: A vertical skein of “fibers”, opposed terminal portions of which are held in headers unconfined in a modular shell, is aerated with a gas-distribution means which produces a mass of bubbles serving the function of a scrub-brash for the outer surfaces of the fibers. The membrane device is surprisingly effective with relatively little cleansing gas, the specific flux through the membranes reaching an essentially constant relatively high value because the vertical deployment of fibers allows bubbles to rise upwards along the outer surfaces of the fibers. Further, bubbles flowing along the outer surfaces of the fibers make the fibers surprisingly resistant to being fouled by build-up of deposits of inanimate particles or microorganisms in the substrate provided that the length of each fiber is only slightly greater than the direct center-to-center distance between opposed faces of the headers, preferably in the range from at least 0.1% to about 5% greater.