Abstract: An object of the present invention is to provide a porous membrane which has a superior separation performance and a high permeation performance, as well as a high mechanical physical property, in particular, a high tensile/rupture strength.

Abstract: To provide a cellulose acetate semipermeable membrane having a high filtration rate and high mechanical strength and which is hardly degraded by microorganisms, the present invention provides a cellulose acetate semipermeable membrane containing a cellulose acetate having an &agr;-cellulose content of not less than 99% by weight, a 6 wt/vol % viscosity of 20 to 220 mPa·s at 25±1° C. and an acetylation degree of 58 to 62%. The cellulose acetate semipermeable membrane is suitable particularly as a hollow fiber membrane.

Abstract: A porous membrane product is provided which is formed from a porous membrane substrate having its surface completely modified with a perfluorocarbon copolymer composition. The porous membrane product has substantially the same permeability as the porous membrane substrate.

Abstract: An asymmetric membrane comprising a tubular polymer film in combination with a tubular braid on which the film is supported, requires the braid be macroporous and flexible, yet sufficiently strong to withstand continuous flexing, stretching and abrasion during use for microfiltration (MF) or ultrafiltration (UF). The specifications for a braid of a long-lived membrane are provided. A membrane is formed by supporting a polymer film in which particles of calcined &agr;-alumina are dispersed, on the defined tubular braid.

Abstract: A medical material composed of a poly(alkyl aryl ether)sulfone copolymer (A) and a thermoplastic polymer (B), such as cellulose triacetate, and being used in contact with the blood, wherein the concentration of the copolymer (A) is at least 40% by weight at least near the surface of a part having a surface to be used in contact with the blood and the copolymer (A) is a specified polysulfone bearing fluorine atoms and polyalkyl ether units and which is suitable for a hollow fiber membrane for artificial kidneys, and the like.

Abstract: The present invention provides a device for concentrating a blood fraction. The device includes an ultrafiltration unit connected to a fluid delivery system for delivering the blood fraction to be concentrated into the ultrafiltration unit. The device also includes a purge fluid delivery system for expelling concentrate from the ultrafiltration unit. In one embodiment, the device accommodates multiple cycles of concentration. A blood fraction concentration method is also provided. The device and method of the present invention are particularly useful for preparing a plasma concentrate suitable for use in a coagulum-based wound sealant.

Abstract: A compound capillary can provide different sizes and configurations for central and outer passages to suit a variety of process applications, in particular methods of separative transport of multi-component samples and precise heat control of fluid streams on a micro scale. The compound capillary can be formed from ductile glass material into an assembly that typically provides a central passageway for retaining one fluid or material and single or multiple outer passages for retaining different fluids or materials. One or more of the different passages may also retain one more different stationary phase to tailor the separative transport to the material of particular sample streams. The compound capillary has particular application to the field of capillary electrophoresis where the multiple capillary passages in a single capillary tube may be used to increase sample through, or used for different function such as cooling and/or the establishment of transverse electrical potentials.

Abstract: A system is provided for withdrawing permeate from a substrate through a filter and for cleaning the filter in situ. The system includes a vessel configured to contain a substrate and a compartment connected to receive substrate from the vessel and connected to return a portion of received substrate to the vessel during normal operation of the system. The system also includes a filter positioned at least partially within the compartment to withdraw permeate from substrate in the compartment during normal operation of the system. A source of cleaning solution is connected to the compartment to deliver cleaning solution into the compartment and into contact with the filter during cleaning operation of the system. The compartment facilitates circulation of substrate in the vessel during normal operation of the system and substantially prevents introduction of cleaning solution from the compartment into contact with substrate contained in the vessel during cleaning operation. A method is also provided.

Abstract: A hollow fiber membrane module comprising a module case and a hollow fiber membrane bundle comprising a plurality of hollow fiber membranes, at least one end of the bundle being bonded to and fixed on the module case, wherein the bonding portions of the hollow fiber membrane bundle and the module case comprise a silicone type resin and in at least one of the bonding portions, a reinforcing rib for reinforcing the bonding portions is directly fixed on the module case. According to the hollow fiber membrane module of this invention, the membrane filtration treatment of water containing ozone over a long period of time and the repeating washing with water containing ozone are made possible.

Abstract: A composite membrane and method for making the same, comprising a porous support and a polyamide surface. The subject membrane provides improved flux and/or rejection rates. The subject membrane is further capable of operating at lower operating pressures. The subject method includes reacting a polyfunctional amine with a polyfunctional acyl halide to form a polyamide. The method includes the step of contacting a complexing agent with the polyfunctional acyl halide prior substantial reaction between the polyfunctional acyl halide and a polyfunctional amine. The subject process is easily adapted to commercial scale manufacturing processes and is particularly suited for making nanofiltration and reverse osmosis composite membranes.

Abstract: A polyacrylonitrile-based hollow fiber filtration membrane, wherein said membrane comprises a sponge structure free from polymer defect sites of sizes larger than 10 &mgr;m inside the membrane, pore sizes of the membrane continuously decrease towards both surfaces of the membrane, and the pore size on the outer surface of the membrane is differentiated from that on the inner surface.

Abstract: A filtering element has ultrafiltration or microfiltration hollow fibre membranes extending horizontally between a pair of opposed horizontally spaced, vertically extending headers. Side plates extending between the pair of vertically extending headers define a vertical flow channel through the element. Modules are created by placing the elements side by side or in an orthogonal grid. A frame restrains the elements in place without obstructing the vertical flow channels. Each element may be released from the frame, however, and removed by sliding it in a direction substantially normal to its headers without disassembling the remainder of the module. The elements have associated releasable water tight fittings between the elements and a permeate collector, the releasable water tight fittings being releasable by removing of an element from the frame. An aerator is located below the module with a plurality of air holes.

Abstract: A method and apparatus for purifying an aqueous suspension comprising feeding an aqueous suspension containing fine particles comprising an inorganic component from the outer surface of a wavy hollow fiber membrane having an outer diameter of from 0.5 to 3.1 mm to filter, followed by physical wash of the hollow fiber membrane. The purifying method can reduce the damage of the membrane outer surface during the physical wash step, prevent open pores on the surface from covering and achieve stable filtration. The hollow fiber membrane bundle can be produced by having a pulsation flow contacted with the hollow fiber material being extruded from the double spinning nozzle under specific conditions and cooling and solidifying or coagulating it while shaking.

Abstract: The invention relates to a method for transferring mass between a flow of a first fluid, preferably a gas phase such as a combustion flue gas, and a flow of a second fluid, preferably a liquid phase, where the first fluid is contacted with the outer surface of porous (semi-permeable) membranes, e.g. polytetrafluoroethylene (PTFE, Teflon ®) membranes, in the form of hollow fibres having gas-containing pores and contacting the second fluid with the inner surface of the membranes. Useful membranes are characterized in that they e.g. have a porosity (&egr;) of at least 0.50, a mass transfer coefficient of e.g. at least 3 cm/s, and a tortuosity factor of e.g. at the most 1.4/&egr; when the porosity &egr; is lower than 0.80 and at the most 1.3/&egr; when the porosity &egr; is 0.80 or higher. The membranes may also be arranged in hollow tubular members where the mass transfer coefficient of the membranes is at least one tenth of the mass transfer coefficient of the gas phase.

Abstract: An improved fluid separating device for filtering a second fluid from a first fluid. The improved fluid separating device comprises a first layer of filter media comprising a sintered matrix of first fibers. A second layer of filter membrane comprises a matrix of second fibers. A third layer of filter media comprises a sintered matrix of third fibers. The first, second and third layers are formed into a lamination with the second layer being interposed between the first and third layers. The second layer has a pore size substantially less than the pore size of the first and third layers for enabling the second fluid to pass through the second layer and for inhibiting the first fluid from passing through the second layer for separating the second fluid from the first fluid. The improved fluid separating device is suitable for separating a gas from a liquid as well as separating a gas from a dissimilar gas.

Abstract: To pot membranes in a header, a dense, viscous liquid, suspension or, preferably, a thixotropic, water soluble gel, is placed in a header pan in space reserved for a permeate channel. A plurality of hollow fiber membranes are collected together and their open ends are inserted into the gel. A fixing liquid, typically a resin, is placed over the gel. The fixing liquid surrounds each membrane and then solidifies, simultaneously sealing the outer surfaces of the membranes and forming a plug in the opening of the header to complete the permeate channel. After the fixing liquid has solidified, the gel is removed by various means. The space initially occupied by the gel becomes part of the permeate channel after the gel is removed. In one embodiment, membranes are grouped by a cushioning adhesive which later surrounds the membranes where they exit the completed header.

Abstract: A hollow fiber separation membrane element and a module thereof which comprise a bundle of a great number of bunches of hollow fiber separation membranes, the bunches of hollow fiber separation membranes being each reinforced with a filament wound therearound. Breakage or rupture of the hollow fiber separation membranes is prevented during production and use.

Abstract: The invention is based on the discovery that certain membranes, which include side chains or molecular “brushes” having, for example, tertiary amino functional groups, can be used as highly effective filters to capture viruses/virus particles from liquids without removal of proteins. New methods based on this discovery include removing viruses from liquids such as blood or plasma, removing viruses from pharmaceuticals, concentrating and/or purifying viruses, e.g., for use in gene therapy, and producing recombinant viruses in new bioreactors. The invention also includes new methods of therapy or adjunct therapy for viral infections, in which a patient's blood or plasma is filtered through the membranes to remove viruses to reduce the viral load. The invention also includes new bioreactors and viral filters containing the membranes.

Abstract: A porous hollow fiber polyvinylidene fluoride resin membrane, characterized in that the membrane has a unitary three-dimensional network structure entirely composed of a polyvinylidene fluoride resin and has an inside diameter of 1.5-5 mm and a wall thickness of 0.5-2 mm and in that the relationship between membrane bubble point and water flux per unit wall thickness is on or above the curve shown in FIG. 1.

Abstract: A filtration device is provided for withdrawing permeate essentially continuously from a multicomponent aqueous substrate containing growing microorganisms in a reservoir. A vertical skein of fiber is scrubbed with coarse bubbles which emanate from a conversion baffle positioned under the skein. The substrate is aerated with fine bubbles in a size range small enough to transfer oxygen to the substrate efficiently. The baffle traps the fine bubbles and converts them to coarse bubbles which are effective to scrub the fibers. In the most preferred embodiment, the finished headers of the skein are derived from composite headers comprising a fixing lamina of resin in which the fibers are potted near their terminal ends, and a fugitive lamina of fugitive powdery material in which the terminal ends of the fibers are potted. The fugitive lamina is removed, preferably by dissolving the powder, e.g. finely divided common salt in water.

Abstract: An air filtering material for air cleaning is formed of a nonwoven fabric of hollow chemical fibers having axial holes containing an oil. The oil exudes through the open ends of the axial holes to wet the surfaces of the hollow chemical fibers to enhance the filtering ability of the air filtering material by binding dust particles by the sticky oil.

Abstract: The present invention relates to a polysufone porous membrane having a high water flux, an excellent resistance to moist heat and an excellent repercolation characteristic, and which comprises a mixed polymer having polyarylsulfone and polyethersulfone at a ratio of from 9/1-1/9 (by weight), the membrane being a graded porous membrane forming a cross-linked polymer network wherein a number of micropores being interconnected from one surface to the other surface, and the membrane comprising two layers wherein one layer being a dense layer having a number of pores with pore sizes in the range of 0.01-1 &mgr;m and thereby having a separation function, and the other layer being a graded type supporting layer supporting said dense layer and having a pore size distribution wherein the pores existing therein and having sizes of 1-100 &mgr;m increase continuously from the dense layer side toward the other surface side, wherein the separation particle size is not larger than 0.

Abstract: A membrane separator assembly for separating solids from water includes opposing enclosure wall structures, a membrane module unit, and a gas diffuser disposed below the membrane module unit. The membrane module unit includes a plurality of membrane modules respectively having at least one separating membrane extending between at least two membrane fixing members. At least one of the membrane fixing members has a main passage which is in fluid communication with a membrane passageway. The membrane passageway is accessible to water via permeation through the separating membranes and is inaccessible to solids which are impermeable relative to the separating membranes. The membrane separator assembly is preferably used with a detergent containing percarbonate, preferably sodium percarbonate. The assembly also includes a gas diffuser with two opposing main pipes and branch pipes extending therebetween to avoid undesired pressure differentials when cleaning the assembly.

Abstract: A composite membrane and method for making the same, comprising a porous support and a crosslinked polyamide surface having polyalkylene oxide groups grafted thereto. The subject membrane provides improved resistance to fouling while offering excellent flux and salt passage performance. The subject method is easily adapted to commercial scale-up and does not require the use of chemical initiators.

Abstract: A hollow fiber membrane made of an ethylene-vinyl alcohol polymer, comprising a dense layer existing in the inner surface and a porous layer existing in the layer other than the dense layer, wherein the hollow fiber membrane has a porosity of 60 to 90%, an overall mass transfer coefficient for myoglobin in a water-based system of not less than 0.003 cm/min., and a rejection rate for albumin in a bovine blood system of not less than 97%. The EVA hollow fiber membrane is useful for hemopurification membranes such as hemodialysis membranes, hemodiafiltration membranes, hemofiltration membranes and continuous hemofiltration membranes, and a process for producing the same.

Abstract: A porous membrane product is provided which is formed from a porous membrane substrate having its surface completely modified with a perfluorocarbon copolymer composition. The porous membrane product has substantially the same permeability as the porous membrane substrate.

Abstract: A membrane module for substance-specific treatment of a fluid includes a housing with a bundle of hollow-fiber membranes with semipenneable, porous walls. The hollow-fiber membranes are embedded in a sealing compound only at one end, and flow around the second end is substantially unrestricted. The lumina of the hollow-fiber membranes are open at the unembedded end and lead into the external space surrounding the hollow-fiber membranes. The fluid to be treated is introduced via an inlet arrangement on only one of the two sides (inside or outside) of the hollow-fiber membranes and directed over this side as a primary stream such that a portion thereof flows as a permeate stream through the wall to the respective other side, the substance-specific treatment taking place on the permeate stream. After passing through the wall, the permeate stream is collected on the other side and reunited with the primary stream in the external space.

Abstract: A filter media system, which is capable of operating in the microfiltration regime, offers: low cost, durability, high temperature and chemical resistance, no particulation, mechanical strength, separation efficiency, and biocompatibility. A filter media system is comprised of a carbon or ceramic composite substrate which contains a carbon or ceramic matrix reinforced with carbon or ceramic fibers. The composite has an array of carbon or ceramic fiber whiskers grown onto its surface or in its bulk. A process is provided for manufacturing the filter media system wherein a carbon fiber is disposed in a matrix deposited by a CVI or LPI process, at temperatures of about 900 to about 1200° C. to achieve a weight gain of about 10 to 200% (the ceramic matrix is deposited by a CVI process from an aqueous slurry or by use of a preceramic polymer). This composite is treated with an aqueous solution of metal catalyst salt and is then heated in hydrogen at elevated temperatures to reduce the metal salt to metal.

Abstract: An apparatus and a method for making a transfer device comprising a tube bundle. The transfer device is suitable for use as a heat exchanger in a blood cardioplegia circuit, for example. The apparatus axially winds a flexible tube around a winding core. The apparatus includes a winding core, a core rotating means, a tube bobbin, and a tube shuttle to guide the tube around the core. A shuttle rotating means rotates the tube shuttle around the core. The method of making the transfer device includes providing a winding core, winding a tube from end to end around the winding core, fitting the wound bundle into a housing, sealing the first and second ends of the housing using a potting material, cutting the ends of the bundle to expose a lumen within the tubes, and attaching a first end cap and a second end cap.

Abstract: The invention relates to a hollow membrane (11) comprising two support layers arranged one above the other forming a space between them and a plurality of capillary tubes arranged between the support layers forming capillary channels for the flow of a first fluid, the space between the capillary tubes forming an internal cavity for the circulation of a second fluid around the capillary tubes, and the whole assembly being made of an organic polymer. These membranes (11) can be assembled into modules for the treatment of a fluid with intermediate porous panels (13).

Abstract: The present invention relates to a dialyzer for blood treatment having incorporated therein a semipermeable membrane which comprises a hydrophobic polymer and a hydrophilic polymer, the water permeating performance of the semipermeable membrane after drying being ½ or higher relative to that before drying and the dialyzer satisfying any of the following requirements: (A) the vitamin B12 clearance is not smaller than 135 ml/min per 1.6 m2; and (B) the amount of the hydrophilic polymer that is eluted from the semipermeable membrane is not higher than 10 ppm.

Abstract: A membrane filtration module, comprising a housing, a semi-permeable membrane, which is accommodated in the housing and has a liquid side for the introduction of liquid to be filtered and a concentrate side opposite the liquid side, as well as a permeate chamber, which surrounds the membrane and is in communication with a permeate-discharge line for discharging permeate. According to the invention, the wall of the housing comprises one or more channels which are closed towards the liquid side and the concentrate side and are in communication with the permeate chamber. These channels act as a permeate discharge.

Abstract: A process for recovering halides from hydrocarbon containing streams is disclosed using a sulfonated hexafluro bis-A-polysulfone membrane of polymers and copolymers having the polymer repeat unit of the formula: in the polymer or copolymer. This process is applicable to recovering and recycling hydrogen chloride, which is used as a catalytic promoter, in hydrocarbon conversion processes such as isomerization and alkylation.

Abstract: A reactor for carrying out gas/liquid/solid phase reactions, comprises a housing (1) which encloses an essentially closed reaction chamber (2) for holding a first liquid phase, the solid phase and a gas phase fed through the chamber; at least one feed (3), connected to the reaction chamber, for feeding a first liquid phase to the reaction chamber (2); at least one hollow fiber (4), the wall of which defines an internal flow channel for at least removing a second liquid phase, such that exchange of matter can take place between the reaction chamber (2) and the flow channel through the wall of hollow fiber (4); at least one discharge (6), connected to the flow channel, for removing the second liquid phase; at least one gas inlet (7) and at least one gas outlet (8), connected to reaction chamber (2) such that, in the use position, the at least one gas inlet (7) opens essentially into the bottom of the reaction chamber (2) and the at least one gas outlet (8) is located essentially at the top of the reaction chamb

Abstract: The present invention relates to produce a polysulfone based hollow fiber membrane, having high water permeable coefficient and excellent permeability with no deterioration of separation capability, characterized by using an internal coagulating liquid and/or an external coagulating liquid containing diethylene glycol(DEG) and/or salt which can form a hydrate in the process of producing the polysulfone based hollow fiber membrane by following steps: (a) Extrude a spinning dope comprising polysulfones resin, organic solvent and polyvinyl pyrrolydone(PVP) into air through a biannular spinning nozzle to obtain an extrudate in the form of a hollow fiber, (b) Simultaneously inject an internal coagulating liquid into the biannular spinning nozzle at inside bore thereof, and (c) Subsequently introduce said extrudate to an external coagulating liquid.

Abstract: A filter element includes a bundle of hollow fiber type separation membranes made of a natural or synthetic macromolecular material and a sealed part made of a thermoplastic resin. The bundle has an opening in at least one terminal part thereof. The sealed part is bonded to the bundle at a temperature not higher than the melting or decomposing temperature of the macromolecular material and adapted to seal watertightly the opening of the bundle in a half-bonded state showing no compatibility with the macromolecular material and permitting persistence of the mutual interface of bondage.

Abstract: An object is to provide a highly integrated hollow fiber membrane module and hollow fiber membrane module unit as filtration processing devices which are appropriate for miniaturization, and to also provide a purification tank with a hollow fiber membrane module unit installed therein. To achieve this there is provided a hollow fiber membrane module in which at least one end of a hollow fiber membrane with hollow fibers deployed in a plane is fixed with a fixing resin to a collector pipe in a fluid tight manner, constructed such that an open ended tip of the hollow fiber membrane is inserted into an aperture provided in the collector pipe, and in this condition, fixing resin is filled into the aperture and hardened, thereby securing the open ended hollow fiber membrane to the collector pipe.

Abstract: An apparatus and process for substance-specific treatment of fluids, whereby the apparatus comprises a housing with a distribution space and a collection space, between which is arranged a structure of adjacent flat first and second layers containing first and second hollow-fiber membranes, respectively, and a matrix on which groups acting in a substance-specific manner for fluid treatment are immobilized, whereby the filling ratio &egr; of the housing determined by the hollow-fiber membranes and the matrix is greater than 0.55. The first hollow-fiber membranes are open in the direction of the distribution space and closed in the direction of the collection space, and the second hollow-fiber membranes are open in the direction of the collection space and closed in the direction of the distribution space, and the hollow fiber membranes are embedded at least at their open end in the sealing compounds.

Abstract: A system is provided for withdrawing permeate from a substrate through a filter and for cleaning the filter in situ. The system includes a vessel configured to contain a substrate and a compartment connected to receive substrate from the vessel and connected to return a portion of received substrate to the vessel during normal operation of the system. The system also includes a filter positioned at least partially within the compartment to withdraw permeate from substrate in the compartment during normal operation of the system. A source of cleaning solution is connected to the compartment to deliver cleaning solution into the compartment and into contact with the filter during cleaning operation of the system. The compartment facilitates circulation of substrate in the vessel during normal operation of the system and substantially prevents introduction of cleaning solution from the compartment into contact with substrate contained in the vessel during cleaning operation. A method is also provided.

Abstract: The present invention is directed to a thermoplastic, unibody transfer device. This transfer device includes a membrane, and a housing surrounding the membrane. The housing includes a thermoplastic end cap and a thermoplastic shell. The end cap and shell are butt welded together. Additionally, there is a method of manufacturing with the aforementioned device. The method includes forming a bundle of a membrane, inserting the bundle into a shell, butt welding an end cap to the bundle and the shell so that the cap, bundle, and shell are fused together.

Abstract: A method for producing an aqueous solution of a polymer having a phosphorylcholine group in which a polymerizable composition containing a polymerizable monomer having the phosphorylcholine group represented by the formula (1) is polymerized in the presence of a non-metal polymerization initiator soluble in a water-containing medium, to obtain a crude polymer aqueous solution, and the crude polymer aqueous solution is purified with a separation membrane, and an aqueous solution of the polymer having the phosphorylcholine group obtained by the method and having not more than 2000 ppm of impurities.

Abstract: A system for preparing autologous plasma comprises a single use filter unit having two inlets in fluid communication with each other, an outlet, and a filtration membrane selectively permeable to blood plasma separating the inlets from the outlet. Manually operable, single use pumps, preferably syringes, connect to the inlets. A flow path is defined along the membrane between the pumps, whereby, whole blood can be repeatedly exchanged between the two pumps, past the membrane, to cause plasma to flow across the membrane and out of the outlet. A syringe can collect plasma from the outlet. Plasma thus collected can be simultaneously applied with a thrombin solution to a site on the body, thereby forming a fibrin gel.

Abstract: Described is a semipermeable capillary having a tubular semipermeable wall composed of a membrane-forming material (2) and a tubular strengthening layer (1). The tubular strengthening layer includes an elongated tape having mutually overlapped longitudinal edges. The tubular strengthening layer has an open cohesive structure that is embedded in the membrane-forming material whereby the mutually overlapping longitudinal edges are joined together by the membrane-forming material and a continuous phase is formed between the semipermeable wall and the strengthening layer.

Abstract: A filter module for filtering raw liquid that includes an outer housing having a longitudinal axis and raw liquid inlet and outlet ends. A non-porous member is attached to each end of the outer housing to form a seal between a hollow tube and the outer housing. A plurality of fins are disposed among hollow fiber filter elements to separate the elements into a plurality of bundles. Each of the fins has a plurality of spacers abutting the hollow tube to form liquid pathways between each of the respective fins in the hollow tube.

Abstract: A permselective graft polymer is disclosed that is formed by converting into intermediate reactive sites a portion of the cyano groups of a backbone polymer containing —CH2—CH(—C≡N)— units, and grafting polyalkylene oxide polymer chains to the backbone polymer through the reactive sites. Either the backbone polymer of a polymer resin or a permselective polymer membrane can be grafted. When a resin is used, it is formed into a permselective polymer membrane using known methods. The resulting permselective membrane can be formed into hollow fibers or flat sheets for the encapsulation of living cells. The encapsulated cells are then implanted into a patient in need of the biologically active factors produced by the cells. The permselective graft polymer membrane exhibits good molecular diffusion with minimal protein adsorption.

Abstract: The invention relates to the use of a neutral or cationic polymer for preventing activation of the contact phase of blood or plasma which comes into contact with a semi-permeable membrane based on polyacrylonitrile bearing fixed negative charges, which is fitted in apparatus for the treatment of blood or plasma by extra-corporal circulation, by combination of the neutral or cationic polymer, before or after formation of the membrane and before its sterilization, so as to modify the electrical properties of the membrane, the Zeta potential “Z” and the electrical resistivity “R” in order to obtain: either an electrokinetic index “I” of less than or equal to 0.8, “I” corresponding to Log10 (|Z|/R), or a positive Zeta potential “Z” of between 0 and 15 mV (limits not included).

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.