Abstract: Embodiments disclosed here include a buoyant filtration system and method including a buoyant rim which may be used to encircle a pollution source and attached to a submersible wall and floor. Some embodiments include the detachable filtration systems on or near the buoyant rim. Some embodiments include a bag attached to the buoyant rim where the bag is water permeable but retains the pollution in the water.

Abstract: A filtration filter comprises a metallic mesh having a circumferential shape and radially inner and outer portions. The metallic mesh is adapted to filter out a filtration target object contained in a fluid passing through the membrane. First and second frame members hold the outer portion there between so as to create first and second bent sections separated by a transition section extending between the first and second bent sections. The transition section includes at least one streaked projection.

Abstract: A filtration assembly for removing solid particulate matter and contaminants from motor oil including, without limitation, motor oil used in internal combustion engines. A housing having a removable cap defines an inner chamber. Stacked sheets of filter materials, interspersed between pressure plates, are installed within the chamber. Pressurized fluid is introduced into the inner chamber; the fluid pressure acts on the pressure plates and compresses the filter materials. As the pressurized fluid passes through the filter materials, solids and particulate matter are filtered from the fluid stream by the filter materials.

Abstract: The invention provides a connector assembly for fastening filter elements onto a supporting plate of a press filter, comprising a first cylindrical core, a first flange extending outward from the first cylindrical core, a second cylindrical core, and a second flange extending outward from the second cylindrical core. The first cylindrical core is shaped and dimensioned such that it snugly passes through and is meshed with a central through hole of the supporting plate, and the second cylindrical core is shaped and dimensioned such that it snugly passes through and is meshed with the first cylindrical core. Both the first cylindrical core and the first flange and both the second cylindrical core and the second flange are respectively molded integrally from a non-woven fabric which has the ability of self-sustaining and shape maintenance, and is moldable. The invention also relates to a press filter fitted with the connector assembly.

Abstract: A filtration system suitable for recovering base stock from used lubricating oil and other applications pass feedstock over nano-filtration membranes assembled as a stack of membranes all experiencing parallel flow. On exiting a first stack of membranes the feedstock passes through an opening in a pressure-sustaining separator plate to flow in the reverse direction past a second stack of membranes and subsequently establish a serpentine flow of feedstock through multiple stacks of membranes. The stacks of membranes all share a common pressure containment vessel. Pressure boosters installed in the flow-through openings of separator plates separating consecutive stacks can serve to restore lost pressure of the feedstock and maintain effective permeation of permeate through the membranes. A pressure control valve at the outlet to the permeate-receiving cavities of a stack can be used to adjust the trans-membrane pressure.

Abstract: A method of bonding a silicone-based element to a textile based element is provided. The method comprises steps that enable a user to bond a silicone-based element to a textile based element using a fibrous material to strengthen the bond. An assembly constructed according to the method is also provided. This assembly is particularly suited to being disposed against skin due to the high biocompatibility of silicone, particularly PDMS.

Abstract: A membrane for a membrane filter plate, having an elastic compression face and a peripheral fastening means. The membrane displays an elastic compression face and a peripheral fastening means. An opening for a fluid communication into a filter chamber is configured in the membrane. The invention furthermore relates to an arrangement of at least two filter plates of which one filter plate is a membrane filter plate having a membrane. One membrane is fastened on the first filter plate by means of the peripheral fastening means such that a compression means chamber is formed between the membrane and the first filter plate. The second filter plate bears on the first filter plate such that a filter chamber is formed between the compression face of the membrane and the second filter plate. At the periphery of the filter plates, a duct is formed between the filter plates.

Abstract: The present invention provides a novel nonwoven felt fabric, which is made of at least one low-melting-point short fiber and at least one high-melting-point short fiber of same type or different types, wherein the fabric is stiff enough to be self-sustaining and have the ability of shape maintenance. The felt fabric exhibits excellent pleatability, moldability and compressive strength. The invention also provides a method for producing the felt fabric, and a filter comprising the felt fabric used as the material of a filter medium of the filter, wherein the filter medium requires no support structure to stand alone and persistently retains its shape.

Abstract: A robust crossflow filtration cassette holder, allowing easy mounting and removal of filtration cassettes. The cassette holder comprises a distributor plate, an end-plate, a plurality of essentially parallel tie rods connecting the distributor plate with the end-plate, and a compression plate slidably mounted on the tie rods between the distributor plate and the end plate, wherein at least one of the tie rods is movable in its entirety between an open position or orientation, allowing mounting or removal of a filtration cassette, and a closed position or orientation, in which the movable tie rod is in engaged connection with the cassette and locks it in the holder by a locking means.

Abstract: The present invention provides for methods and systems that effectively separate dispersed FOG from emulsions and/or free-floating FOG from a waste stream to provide dewatered emulsions and/or separated fats, oils and greases from emulsions thereby providing value added separated product while reducing disposal of solid or liquid waste matter into landfills or water treatment facilities.

Abstract: A filter plate having a basic body and an elastic element which is fastened to the basic body in an annular and liquid-tight manner. The filter plate is distinguished by the fact that a temperature-control plate is fastened to the elastic element.

Abstract: The present disclosure is directed at a compression device for compressing a stack to prevent leaks and at an apparatus including the stack and the compression device. The stack includes a pair of rigid end plates located at opposing ends of the stack, a plurality of membrane bounded compartments layered between one of the rigid end plates and the other of the rigid end plates and fluid manifolds extending through the membrane bound compartments. The compression device is fixedly coupled to opposing ends of the pair of rigid end plates and includes compression members movable to compress one of the rigid end plates towards the other of the rigid end plates. The compression members are positioned to apply force to the stack in the vicinity of the fluid manifolds.

Abstract: A filter (20) configured to separate the solid components and the liquid components from a slurry. The filter (20) includes a plurality of filter plate assemblies (46) that cooperate to define a plurality of filter chambers (70), each defining a perimeter (96) having an open section (98) when the filter plates (68) are in a closed position relative to one another. Each filter plate assembly (46) includes a closure (104) configured to close the open section. Preferably, the closures (104) are movable to an open position to permit a particulate cake to be removed from the filter chambers (70) without separating the filter plates (68).

Abstract: The present invention concerns a filter press (10, 60), comprising a supporting frame, constituted of at least one longitudinal rail or guide (11, 61) supported at its opposite ends by a fixed headpiece (12, 62) on one side and by a foot (13, 63) on the other side, a movable headpiece (15, 65) supported by said at least one guide (11, 61), a plurality of filtering plates (14, 64) arranged side by side between said fixed headpiece (12, 62) and said movable headpiece (15, 65), pneumatic elements or cushions (20, 70) for pressing and a compression plate (21, 71), wherein said movable headpiece (15, 65) comprises threaded cylindrical holes, supported on relative endless screws (19, 69) the ends of which are rotationally mounted on supports integral with the relative guides (11, 61).

Abstract: A membrane plate, a filter plate, and a filter press. The membrane plate is outfitted with a filter element on top of the membrane on both side surfaces, and the membrane plate has retaining elements at a distance from the margin on which the filter elements are removably secured. The filter plate also has retaining elements at a distance from the margin on which the filter elements are removably secured.

Abstract: A method of separating a mixture of liquid and insoluble solids in a filter press may comprise: pumping the mixture into a chamber between two filter plates in the filter press to form a filter cake, wherein the chamber is lined by filter cloths, and wherein, during the pumping, filtrate is forced through the filter cloths and out of the chamber; heating the filter cake in the chamber, wherein, during the heating, filtrate is forced through the filter cloths and out of the chamber, and wherein the heating is by radio frequency irradiation of the filter cake in the chamber; and releasing dried filter cake from the chamber.

Abstract: A solid-liquid separation device includes a plurality of fixed members and movable members that are movably disposed between the adjacent fixed members, and a screw extending through the fixed members and the movable members in a state where the screw is not in contact with the fixed members and the movable members. The screw is rotationally driven about a center axis line thereof. A filtrate separated from an object is discharged to the outside of the solid-liquid separation portion through filtrate discharge gaps, and the object that has a reduced liquid content ratio is discharged from the outlet to the outside. In order to increase significantly a dewatering ratio, the movable members are formed to move while penetrating closer to the center axis line of the screw than an outer circumferential edge of the blade of the screw, without coming into contact with the screw.

Abstract: A filter press including a top plate and an end plate that are connected by at least one connecting rod with the interposition of a packet of chamber plates. Between adjacent pairs of chamber plates, a respective filter chamber can be produced and a clamping device is provided, which is able to bring the chamber plates into an operating position in which the filter chambers are pressed against one another in a sealed fashion and to release the chamber plates into an open position in which the filter chambers are openable, wherein a removable spacer plate and a clamping device in the form of a pressing unit that can be acted on with a working fluid are provided between the top plate and the end plate.

Abstract: A chamber filter plate for a filter press includes a plate plane having a longitudinal direction and a crosswise direction. A plate body has a surface with a thickness. A plate edge frames the plate body and is thicker than the surface of the plate body. The plate edge has at least one hollow channel formed therein, extending in the longitudinal and/or crosswise direction. A method of producing a chamber filter plate is also provided.

Abstract: A leakage indicator is provided for a filter element of a filter press, in which the filter element has at least one membrane that can be impinged by a pressure medium. In order to create a leakage indicator that is constructed in a particularly simple manner, an indicator body is freely movable in a flow chamber. Any change in position of the indicator body, which is caused by inflowing or outflowing pressure medium, can be monitored visually or through the use of sensors.

Abstract: A filter cartridge is described that is designed to accommodate multi-stage filtration, for example dual stage filtration. A filter cartridge includes an outer filter with an endplate and an inner filter arranged within the central axis of the outer filter and that includes an endplate. The endplate of the outer filter includes an outer portion and an inner portion substantially surrounded by the outer portion. The inner portion is axially positioned relative to the outer portion and distal to the inner and outer filters relative to the outer portion. The inner portion includes an upwardly extending flange. The endplate of the inner filter includes a downwardly extending flange. The endplates of the outer and inner filters are arranged in a snap fit connection through engagement of the upwardly extending and the downwardly extending flanges. The endplate structure can provide a filter cartridge with filters of generally equal lengths.

Abstract: A membrane filter plate for a filter press includes a membrane fastened in the filter plate. The membrane has a flexible support layer, a central region with a functional layer different from the flexible support layer, and edge regions free of the functional layer.

Abstract: A filter panel contains a sludge inlet, a distributor ring which is arranged at the sludge inlet and has at least one inlet channel, and a support ring assigned to the distributor ring. A protective lip is mounted on the support ring and rests on the distributor ring in its closed position and partly covers the inlet channel.

Abstract: A portable water disinfecting and purification apparatus comprising a first chamber into which water to be purified may be drawn by suction or negative pressure, a second chamber into which the water from the first chamber can be forced by a pumping action or positive pressure, whereby the water is initially passed across a pre-filter secured over the inlet to the first chamber and having a very small pore size and an inner cavity in which a disinfecting agent is place to filters most contaminants before the water is drawn into said filtering device, and once in the first holding chamber the water is isolated and may be further treated with a disinfectant agent, and then is passed though at least additional filtering substance including an activated carbon or nano-filter.

Abstract: An oil filter arrangement comprises a housing, which has a receiving chamber for a filter element which can be cross-flowed in a radial manner by oil and which can be inserted into the housing, a support tube which supports the filter element when it is inserted, a housing cover which closes the receiving chamber, and a drainage channel which is provided in the base area of the receiving chamber. The support tube is fixed to the housing and it remains therein when the filter element is replaced and that a drainage plate, which comprises closing means for closing the drainage channel and which is arranged in an axially displaceable manner, to a limited extent, on the support tube, is arranged in the base area of the receiving chamber.

Abstract: A separator for cleaning a fluid stream, in particular for removing oil from a gas stream, has a filter medium separating contaminants from a fluid stream. A bottom plate is arranged at a first end of the filter medium and a cover plate is arranged at a second end of the filter medium. A support body is provided and the filter medium is arranged concentrically on the support body. The filter medium, the bottom plate, the cover plate and the support body are essentially free of metal and withstand a high differential pressure between an outer side and an inner side of the separator.

Abstract: Methods and devices are provided for preparing and separating biological analytes. In one embodiment, one or more filtration devices or filter plate wells can be formed by clamping a filter sheet between first and second plates having at least one connecting cavity. First and second moveable core pins positioned on opposed sides of the sheet can be moved to remove portions of the sheet. A molten plastic can be injected to fill the volume between the cores and cavities and to form a liquid-impermeable sleeve wall or walls, each being separately sealed at the bottom to the perimeter of the sheet portion, each having liquid permeable regions of said removed and sealed sheet portion, and each remaining open at the top. Various exemplary configurations for filtration devices or filter plate wells are also disclosed.

Abstract: The invention relates to a membrane filter press. On operation of such a press a secure generation of the necessary pressing pressure can be guaranteed with a membrane filter press that has at least one membrane filter plate, a baseplate with thickened edge region, a membrane made from an elastically-deformable material, and a filter cloth. The novel membrane has an annular edge bead which lies in a complementary groove on the baseplate. A sealing groove is formed into the baseplate which opens out into the first-mentioned groove at both ends in the manner of a bypass. A complementary sealing projection, moulded on the annular bead, engages in the sealing groove with formation of a seal. The cavity enclosed between the groove and the sealing groove is preferably provided with at least one filtrate drain bore.

Abstract: An apparatus for industrial wastewater treatment and the electrolytic recovery of metals from solutions is disclosed. It comprises two or more plates with electricity conducting surfaces arranged in parallel and separated by insulating gaskets, two heads and a hydraulic ram or other mechanical means to press the group of plates between the heads. Plates and gaskets pressed together form chambers where metal recovery and other electrochemical reactions take place. Holes bored on the plates or on the gaskets separating them allow the solutions to flow in and out of the chambers. The solutions in the chambers close the electrical circuit between the conducting surfaces of the plates and allow an electrical current to flow from one plate to the other closing also a circuit between the terminals of an electrical current source.

Abstract: A system for moving a filter or a retainer into or out of a fluid pathway without halting the movement of the fluid in the pathway. When acting as a filtering device, the system includes a filter frame and a drive mechanism for slidingly moving the filter frame on stationary rails that remain in the duct through which the fluid is transferred. When a retainer device, the system includes a retainer and a drive mechanism for slidingly moving retainer on stationary rails that remain in the chamber through which a fluid under treatment passes. The system includes isolation means permitting the filter frame or retainer to pass into or out of the duct or chamber without exhausting the fluid within the duct or chamber. The drive mechanism may be a guillotine damper gate drive, a spindled drive, a hydraulic actuator or other drive means. The filter or the retainer may include a plurality of bays that are rigidly, hingedly, or detachably connected together.

Abstract: A liquid-liquid extraction system including an outer chamber and an inner chamber. The outer chamber is adapted to contain one of a feed solution and a liquid extractant and defines a containment region. The inner chamber is adapted to contain the other of the feed solution and the liquid extractant within a lower portion of the inner chamber. The inner chamber is defined by a microporous membrane sleeve that internally maintains a frame. Upon final assembly, at least the lower portion of the inner chamber is positioned within the containment region of the outer chamber such that the microporous membrane sleeve establishes an extraction interface between contents of the inner and outer chambers. In one embodiment, the flow region of the microporous membrane sleeve is immersed within a feed solution otherwise contained within the outer chamber.

Abstract: The invention relates to a device and an assembly for cross-flow filtration comprising filter cassettes. Said filter cassettes are cost-effective to produce as they have few connections and simple clamping plates and are characterized by a long service life and by being highly flexible in adapting their capacity to the desired cross-flow filtration performance. The inventive device (1) comprises a holder and at least one filtration segment (2) consisting of clamping plates with filter cassettes fitted in a sealed manner therebetween. The clamping plates, which are configured as end plates, separation plates, distribution plates and collection plates and the filter cassettes are positioned on the holder so that they can be moved towards one another.

Abstract: The invention relates to a filter module (4) with a simplified design which allows for the manufacturing of a step filter, Each ply of filter medium is composed of a deep-bed filter material layer (1, 1a-d) and the packing is composed of draining layers (5, 5a, 5b). The draining layers (5, 5a, 5b) and filter layers (5, 5a, 5b) are mutually sealed to the filtrate/non-filtrate chamber (2,3). The filter layers (1, 1a-d) can be arranged according to any pattern.

Abstract: The invention relates to a device and an assembly for cross-flow filtration comprising filter cassettes. Said filter cassettes are cost-effective to produce as they have few connections and simple clamping plates and are characterised by a long service life and by being highly flexible in adapting their capacity to the desired cross-flow filtration performance. The inventive device (1) comprises a holder and at least one filtration segment (2) consisting of clamping plates with filter cassettes fitted in a sealed manner therebetween. The clamping plates, which are configured as end plates, separation plates, distribution plates and collection plates and the filter cassettes are positioned on the holder so that they can be moved towards one another.

Abstract: In one embodiment, a membrane stack is described for separating dialysate and diffusate. The membrane stack comprises a plurality of membrane sheets and a plurality of spacers interspersed between the plurality of membrane sheets. Each spacer includes a gasket bordering a screen diagonally woven. These membrane sheets and spacers are affixed together by form a collective unit.

Abstract: The filter cake in a filter press is heated by direct contact with a heating plate opposite the pressing membrane so that a vapor phase is generated which moves uniformly in a planar pressure front through the filter cake to dry residual liquid therefrom. The filter cake is maintained under vacuum during the drying step.

Abstract: A media is used to remove species from aqueous solutions, particularly in the treatment of water to enable it to be suitable for drinking. The media includes a material selected from the group consisting of zirconium hydroxide, titanium hydroxide, hafnium hydroxide and combinations thereof. A preferred form of the media is a layer having an aspect ratio of at least 1:1, more preferably, at least about 10:1. Removed from the water are species selected from the group consisting of arsenate, selenate, chromate, borate, perchlorate, fluoride and combinations thereof. In particular arsenite (As+3) containing species are also removed from water. Arsenite may be removed from water to levels not greater than 10 parts per billion with a single exposure to the media. The media is selective for certain species over others.

Abstract: A filter device, particularly for filtering melt-type fluids, such as polymer melts, includes at least one filter disk having two filter disk halves connected to each other by their edges and provided with filter material on their exterior surfaces. The filter disk halves are held apart by a supporting device delimiting a substantially free hollow area between them, through which a fluid can flow freely. Inwardly, they delimit an outflow opening for the melt-type filtered fluid. The supporting device has individual supporting cams of substantially equal outer dimensions and arranged in several groups. Separated from each other, the supporting cams extend radially outwardly form the outflow opening, are rigidly connected to at least one of the two halves, and traverse the hollow area in such a way as to rest against the other filter disk half. This results in a filter device which is economical to produce and which has enhanced filter performance when in operation.

Abstract: A grid (250, 280) is disclosed which can be used as part of a salt platform (10, 50, 80) to support salt in an ion exchange water softener. The grid is preferably formed of ABS plastic and has a border portion (252) and bands (254, 256) without holes (274) formed therethrough for strength. When the grid is used as part of a salt platform having vertically oriented members (12-24) with open upper ends, cap portions (258-270), without holes formed therethrough, are used to cover the upper ends of the members. A ring (350) can be used to fit the salt grid in the brine tank.

Abstract: A filter sheet positioned between plates (14) of a filter press has a fluid-impermeable wax layer (11) sealing the sheet's perimeter. The wax preferably comprises ethylene bis stearamide and has a durometer reading of about 75 to about 100 Shore A hardness at 25.degree. C. and 85.degree. C., a melt point of about 110.degree. C. to about 180.degree. C., and a viscosity of less than about 100 cp at 155.degree. C. The wax layer increases the useful life of the filter sheet while providing a sheet which is easily released from a filter press and which retains integrity along the seal during repeated hot water sanitations.

Abstract: A self supporting filter plate assembly having two opposed screen sections with inwardly shaped deformations which engage each other to maintain a planar surface of the screen sections at a predetermined spacing. The screen sections releasably engage each other. Inwardly directed retaining pins of an exterior frame removably support the screen sections in place within the frame. Each of the screen sections include edges which are bent at 90.degree. with respect to a central planar portion of each screen. The edge portions of the two screen sections interengage with each other by a projection in an inner surface of an edge portion of one screen section engaging with a recess extending from an outer surface of an edge portion of the other screen section. In addition, spaced openings in the edge portions, on opposed side edges of both screen sections, interengage with the inwardly directed retaining pins extending from an inner surface of opposed sides of the frame.

Abstract: A filter membrane element for a membrane separation unit for use in a water treatment apparatus or the like, and a method of manufacturing the same. An organic filter membrane including a plate-like support member made of nonwoven fabric and a film coating formed on both sides of the support member is joined with a surface of a filter plate, whereby the filter membrane element is formed. A portion of the film coating is dissolved to cause the support member to be exposed at that portion. Subsequently, the exposed portion of the support member is joined by adhesion or otherwise with a corresponding portion of the filter plate.

Abstract: A filter-plate assembly has a support plate having an outwardly directed face and formed with an annular groove opening outward at the face and a chamber plate confronting the face of the support plate, forming therewith an inlet compartment, and formed with an inlet-port cutout opening into the compartment. A flexible filter plate adjacent the support plate has an outer peripheral frame set in the groove and a generally planar central panel within the frame and having a back face turned toward and forming a compartment with the face of the support plate and a front face turned away from the support plate and adapted to be overlain by a filter cloth. A rigid retaining bar overlying the frame extends parallel to it at the cutout. Bolts or the like secure the retaining bar relative to the support plate against the frame to hold the frame tightly in place in the groove of the support plate at the cutout.

Abstract: A plate filter press with chamber plates and diaphragm carrier plates and diaphragms secured thereto is provided that makes it possible to provide an adequately large, radial slurry admission cross-section that remains free of blockage. An annular supporting collar that respectively embraces the aperture edge of the chamber plate and has a U-shaped cross-section in its edge region is arranged in the central flow-through opening of every chamber plate, whereby the end of each U-leg comprises an annular seating wedge for supporting the arched diaphragm. The seating wedge extends in the direction of the respectively neighboring diaphragm and does not constrict the radial flow channel to the respective filter space.

Abstract: A filter-plate assembly has a backing wall having an outwardly directed face and formed with an annular groove opening outward at the face and of a predetermined transverse width and a filter plate adjacent the wall and having an outer peripheral frame set in the groove and of a width substantially less than the width of the groove so as to define therewith an outwardly open annular gap. A generally planar central panel within the frame has a back face turned toward and forming a compartment with the wall and a front face turned away from the wall and adapted to be overlain by a filter cloth. A retaining bar is set in the space and braced transversely between the frame of the element and the backing wall.

Abstract: A plate module and its use for separating fluid mixtures according to the methods of pervaporation and vapor permeation is comprised of a feed plate, a cover plate, a gasket, and a membrane to define at least one feed compartment and one permeate compartment. The feed compartment is connected to supply and removal ducts. The feed plate is formed as a single plate with no welding or deformation. Changes in the feed plate and distribution ducts can be easily effected without additional costs.

Abstract: A thorough wash operation of a process fluid is conducted within the confines of an enclosed housing. The housing includes four ports at one side of the housing for transmission of process fluids through a plurality of press frames so as to (1) separate solids from a principal liquid to recover a valuable commodity in the solid cakes formed from the principal liquid, or (2) remove contaminants from the principal liquid so as to recover a cleansed principal liquid, or (3) introduce a valuable commodity into a wash liquid from filter cakes formed from the principal liquid, which valuable commodity may subsequently be removed from the wash liquid. A drip pan hopper is removably secured to a bottom of the housing.

Abstract: A beer filtering device of a filter press type for filtering a beer stock. The beer filter device includes a plurality of filter plates (4) and a plurality of filter frames (6) arranged side by side in alternate relationship to each other. A filter element (28) is supported to each filter plate (4). A stock line (66) for supplying a beer stock and a filtrate line (68) for discharging a filtrate of the beer stock are so formed as to penetrate through the filter plates and the filter frames in the thickness direction thereof. The stock line and the filtrate line are sealed by a plurality of stock line seals (48) and a plurality of filtrate line seals (74), respectively, each interposed between the filter plate and the filter frame adjacent to each other in a filtering step. A plurality of washer liquid seals (76) are provided outside the stock line seals and the filtrate line seals in such a manner that each washer liquid seal is interposed between the filter plate and the filter frame adjacent to each other.

Abstract: A filtration cassette, of a type comprising membrane filter sheets arranged in a peripherally bonded array of multilaminate character wherein the filter sheets alternate with foraminous (e.g., screen or mesh) sheet elements, and a cross-flow filter comprising a multiplicity of stacked filtration cassettes of such type. The filtration cassettes and filter of the invention may be advantageously employed for dewatering of aqueous biomass suspensions, desalting of proteins, removal of secreted metabolites from cellular suspensions, and the like.

Abstract: A spiral filtering device disposed within a frame consisting of two draw bars and two end pieces. The spiral filter consists of at least one spiral plate and at least two support plates with attached filter plates inserted between two end plates. On each of their plane machined surfaces, the spiral plates have a spiral groove of approximately semicircular cross-section. In addition, each surface of the spiral plate has a round depression with a boss in the shape of the bottom of a bottle. The groove is surrounded by a circular channel which is also recessed. The helicity of both grooves on the surfaces of the spiral plates is the same. The outer ends of the grooves are interconnected by a drilled channel at a shallow angle to the surface of the spiral plate. The inner ends of the grooves are connected to their respective recesses by a drilled channel running substantially parallel to the surface of the spiral plate.