MXPA00008180A

MXPA00008180A - Rotary disc filtration device with means to reduce axial forces

Info

Publication number: MXPA00008180A
Application number: MXPA/A/2000/008180A
Authority: MX
Inventors: Philip M Rolchigo; Leonard T Hodgins; Guanghua Yu
Original assignee: Membrex Inc
Priority date: 1998-02-24
Filing date: 2000-08-21
Publication date: 2002-03-05

Abstract

Rotary disc filtration devices and filtration processes using those devices are disclosed. The devices (20) have one or more fluid filtration gaps (40) into which fluid to be filtered into permeate and retentate is placed. Each fluid filtration gap is defined by a disc and a filter, one of which rotates with respect to the other. The filter is carried on a filter support member (34). Fresh feed is introduced to each fluid filtration gap (40) near the longitudinal axis of the shaft (28) on which the discs (36) are rotated. Holes (66) through the disc (36) in the active area of the disc (36), which is the area opposite the filter (42), counter act the tendency of the disc (36) and filter (42) to move towards one another.

Description

ROTATING DISC FILTRATION DEVICE WITH MEANS TO REDUCE AXIAL FORCES TECHNICAL FIELD This invention relates to the field of filtration and more specifically, to rotary disk filtration devices.

BACKGROUND Filtration devices are used to separate one or more components of a fluid to other components. Common processes carried out in such devices include classical filtration, microfiltration, ultrafiltration, reverse osmosis, dialysis, electrodialysis, pervaporation, water separation, screening, affinity separation, affinity purification, affinity absorption, chromatography, filtration. gel and biological filtration. As used herein, the term "filtration" includes all those separation processes as well as any other process that uses a filter that separates one or more components of a fluid from the other components of the fluid. Accordingly, the term "filter" includes metal and polymeric cloth filters, semipermeable membranes and inorganic screen materials (eg, zeolites, ceramics). A filter can have any shape or shape, for example, woven or non-woven fabrics, fibers, membranes, screens, sheets, films and combinations thereof. The components of the fluid that pass through the filter comprise the "permeate" and those that do not pass (ie, are rejected by the filter or are retained by the filter) comprise the "retentate". The useful fragment derived from the filtration process can be the retentate or the permeate or in some cases both can be useful. A common technical problem in all filtration devices is clogging or clogging the filter. The permeate that passes through the filter from the fluid layer adjacent to the feed side of the filter leaves a retentate layer adjacent to or on that side of the filter having a different composition than that of the bulk feed fluid. This material can bind to the filter and clog its pores (ie, dirty the filter) or remain as a boundary layer at rest, any of which inhibits the transport of the components that attempt to pass through the filter to the side of the permeate. of the filter. In other words, the transport of mass per unit area through the filter per unit of time (ie, flow) is reduced and the inherent screening capacity of the filter is adversely affected. Generally, fouling of the filter is of a chemical nature, which includes the chemisorption of substances in the feed fluid in the outer and inner (pore) surface areas of the filter. Unless the chemical properties of the filter surface are altered to avoid or reduce adsorption, costly replacement or filter cleaning operations are necessary. One of the most common causes of fouling originates from the low surface energy (eg, hydrophobic nature) of many filters. The Patents of E.U. Nos. 4,906,379 and 5,000,848, which are assigned to Membrex, Inc., assignee of the present application, describe chemical modifications to increase the surface free energy (eg, hydroplicity) of the free surfaces. (All documents identified, described or otherwise referenced in this application are hereby incorporated in their entirety for all purposes). However, in general, relatively little attention has been given to modifying the surface chemistry to reduce fouling of the filter. In contrast to the chemical nature of most fouling problems, the formation of a boundary layer near the filter surface is physical in nature, resulting from an imbalance in the mass transfer of the feed fluid components to the surface of the filter compared to the reverse transfer from the boundary layer to the bulk feed fluid. Some type of force (for example, mechanical, electro-chemical) should be used to accelerate the desired mass transfer away from the filter surface. Unfortunately, few strategies have been developed that accelerate proper reverse mixing to reduce the boundary layer or prevent its formation. The most common strategy is called "cross flow" filtration ("CFF") or "tangential flow" filtration ("TFF"). In principle, the feed fluid is pumped through (i.e., parallel to) the outer surface of the filter at a sufficiently high speed to interrupt and reverse mix the boundary layer. However, in practice, the transverse flow has several disadvantages. For example, equipment should be designed to handle the higher flow rates that are required, and such higher flow rates generally require recirculating the retentate. However, recirculation may damage some materials that may be present in the fluid (eg, cells, proteins) and render them unsuitable for later use (eg, in tests). A different approach to removing the limit layer at rest involves decoupling the feed flow rate from the applied pressure. With this approach, a structural element of the filtration device, rather than the feed fluid, moves to effect reverse mixing and reduction of the boundary layer. The moving body can be the filter by itself or a body located near the filter element. Some of the rare moving body devices that have improved filtration without inefficient energy turbulence are exemplified in US Patents.

No. 4,790,942, E.U. 4,876,013, and E.U. 4,911,847, (assigned to embrex, Inc.). These three patents each describe the use of filtering apparatuses comprising external and internal cylindrical bodies that define an annular recess for receiving a supply fluid. The surface of at least one of the bodies defining the gap is the surface of a filter, and one or both of the bodies can be rotated. The rotational flow induced between these cylinders is an example of unstable fluid stratification by centrifugal forces. The principle of this instability can be expressed with the help of a characteristic number known as the Taylor number. Above a certain value of the Taylor number, a vorticuous flow profile comprising the so-called Taylor vortices appears. This type of secondary flow causes highly efficient non-turbulent shear in the filter surface (s) which reduces the thickness of the boundary layer at rest and, consequently, increases the flow of the permeate. In contrast to classical cross-flow filtration, the devices of the US Patents. No. 4,790,942, E.U. 4,876,013 and E.U. 4,911,847, allow independent control of the shear rate near the filtration surface and the transmembrane pressure. In addition, because these two operating parameters are independent and because high feed rates are not required to improve permeate flow, the feed rate can be adjusted to avoid non-uniform transmembrane pressure distributions. According to the above, mechanically agitated systems of this type allow precise control during separation. The rotary disk filter devices also allow the shear rate close to the filtration surface and the transmembrane pressure to be controlled independently. In such devices the feed fluid is placed between the disc and positioned opposite the filtration surface defining the fluid filtration gap and one or both of the disc and the filtration surface are rotated. See, for example, the US Patents. Nos. 5,143,630 and 5,254,250 (both assigned to Membrex, Inc.). Additional documents relating to rotary impellers, rotating discs, filtration, rotary disc filtering devices, other filtering devices that use mechanical agitation, and seals include: US Patents. No. 1,762,560; E.U. 3,455,821; E.U. 3,477,575; E.U. 3,884,813; E.U. 4,025,425; E.U. 4,066,546; E.U. 4,132,649; E.U. 4,216,094; E.U. 4,311,589; E.U. 4,330,405; E.U. 4,376,049; E.U. 4,592,848; E.U. 4,708,797; E.U. 4.717, 85; E.U. 4,781,835; E.U. 4,867,878; E.U. 4,872,806; E.U. 4,906,379; E.U. 4,950,403; E.U. 5,000,848; E.U. 5,599,164; Austrian Patent Description 258313; Published European Application Nos. 0 226 659, 0 227 084, 0 304 833, 0 324 865, 0 338 433 0 443 469 and 0 532 237; German Patent Specification 343 144; PCT Published Application WO 93/12859; PCT Published Application WO 97/19745 (corresponding to U.S. 5,707,517, owned by Membrex, Inc.); R.U. 1,057,015; Aqua Technology Resource Management, Inc., "How to Keep Your Fluid Processing Budget from Going to Waste", 3 page booklet; Aqua Technology Resource Management, Inc., 4-page brochure (without title) that describes "Technology Background", "Overcoming Concentration Polarization", etc .; Fodor, "Mechanical Seáis: Design Solutions for Trouble Free Sterile Applications", Bioprocesses Engineering Symposium, The American Society of Mechanical Engineers (1990), pages 89-98; Ingersoll-Rand, "Upgrade your entire filtering and / or washing operation with the new Artisan Dynamic Thickener / Was er", Bulletin No. 4081, 4 pages (2/86); Ingersoll-Rand, "Patented filter / wash capability with simultaneous washing and filtering", Bulletin No. 4060, 4 pages (8/83), Lebeck, Principles and Design of Mechani cal Face Seáis, pages 17-20, 107, 146 ( John Wiley &; Sons, Inc. 1991); Molga and Wronski, "Dynamic Filtration in Obtaining of High Purity Materials - Modeling of the Washing Process", Proceedings of the Royal Flemish Society of Engineers, Antwerp, Belgium, October 1998, Volume 4, pages 69-77; Murkes and Carlsson, Crossflow Filtration - Theory and Practice, pages 69-99, John Wiley & Sons, New York (1988); Parkinson, "Novel Separator makes Its Debut", Chemical Engineering (January 1989), 1 page reprint by Aqua Technology Resource Management, Inc .; Rudniak and Wronski, "Dynamic Microf ilt rat ion in Biotechnology", Proceedings lst Event: Bioprocess Engineering, Institute of Chemical and Process Engineering, Technological University of Warsaw, Warsaw, Poland, June 26-30, 1989; Schweigler and Stahl, "High Performance Disc Filter for Dewatering Mineral Slurries", Filtration and Separation, January / February, pages 38-41 (1990); Shirato, Murase, Yamazaki, Iwata and Inayoshi, "Patterns of Flow in a Filter Chamber during Dynamic Filtration with a Grooved Disk", Int ernational Chem. Eng., Volume 27, pages 304-310 (1987); Snowman, "Sealing Technology in Lyophi 1 i zers", in Bioproces s Engineering Symposium, The American Society of Mechanical Engineers (1989), pages 81-86; Todhunter, "Improving the Life Expectancy of Mechanical Seis in Aseptic Service," Bioprocess Engineering Symposium, "The American Society of Mechanical Engineers (1989), pages 97-103; Watabe," Experiments on the Fluid Friction of a Rotating Disc with Blades " , Bulletin of JSME, Volume 5, number 17, pages 49-57 (1962), Wisniewski, "Anticipated Effects of Seal Interface operating conditions on Biological Materials", Bioprocess Engineering Symposium, The American Society of Mechanical Engineers (1989), pages 87-96, Wronski, "Filtracja dynamiczna roztworow polimerow", In z.Ap. Chem., Number 1, pages 7-10 (1983), Wronski, Molga and Rudniak, "Dynamic Filtration in biotechnology", Bioprocess Engineering, Volume 4 , pages 99-104 (1989), Wronski and Mroz, "Power Consumption in Dynamic Disc Filters", Filtration &Separat ion, November / December, pages 397-399 (1984), Wronski and Mroz, "Problems of Dynamic Filtration" , Reports of the Institute of Chemical Engineer ng, Technological University of Warsaw, T.XI, z.3-4, pages 71-91 (1982); and Wronski, Rudniak and Molga, "Resistance Model for High-Shear Dynamic Microf ilt rat ion", Filtration & Separat ion, November / December, pages 418-420 (1989). Conventional rotary disk filter devices use stacked filter disk arrays. Historically, most of these devices comprise disk filters that are rotated by means of a central drive shaft to which the filter elements are attached. Some rotating disk devices use stationary filter discs separated from each other by rotating elements attached to the shaft. Murkes and Carlsson, Crossflow Filtration - Theory and Practice, John Wiley & Sons, New York, (1988), Fig. 3.15 on page 91. In this type of device a unitary stationary filter element unit surrounds the central rotating drive shaft. The effectiveness of rotary disk filtration devices depends to a large extent on the flow paths of the feed, retained and permeate fluids.

Means to overcome the potential for formation of rejected species caused by flow path limitations may involve changing either the design of the rotating disk (e.g., adding blades or slots), or changing the feeding paths, or both. In some designs, the feed fluid is introduced near the peripheries of the filter (s) and disk (s). In other designs, the feed fluid is introduced near the rotary shaft (longitudinal axis of the filter (s) and disk (s)) and the feed fluid can be provided to the filter gap (s) of fluid through hollow rotating shafts that have ports (or nozzles) to direct the feeding to either or both sides of the filter holder members. It has been found that in some cases during the use of a rotating disc filtering device, the disc and its adjacent filter defining the fluid filtration gap can be contacted with each other, which is highly undesirable (eg, the Union "or" friction "of the disc against the filter can significantly increase the power requirements, the filter may be damaged, and the rotating bearings may suffer premature wear or failure). Despite all the development work regarding disc filtering devices, there is still a need for rotating disc filtering devices that can prevent such contact and the resulting problems.

DESCRIPTION OF THE INVENTION Such devices have now been developed. In accordance with this invention, it has surprisingly been found that providing, in combination with the other elements of the invention, a second feeding means in the active area of a disk that defines a fluid filtration gap will significantly alleviate these problems and provide other benefits. This was particularly surprising because placing the second feeding means in the inactive (non-active) area of the disc does not appear to alleviate these problems or provide the benefits of this invention. The active area of the disk is that portion of the disk that is placed opposite the active area of the filter (which is the "active filtration area"). Therefore, it is the active filtration area of the filter and the active area of the disc that are placed opposite each other through the fluid filtration gap that those two active areas define. If the preferred spiral grooves are used in the disc, the active area of the disc will typically correspond to the grooved area because the grooves would not typically be placed on the disc except where the filter was directly opposite to define the fluid filtration gap . The second feeding means are desirably through holes (holes) in the disc. It is assumed that the use of the second feeding means in combination with the other elements of the device reduces the external forces to the system (pressures) acting on the two surfaces defining the gap trying to move those two surfaces together. Other alleged unexpected benefits of the invention are that any starvation of the filtration process that is carried out in the gap is avoided and the tendency to soil the filter defining the gap is reduced or eliminated. These benefits, as well as others, will be apparent to those skilled in the art from this description. In general, in one aspect this invention relates to a rotating disc filtering device for filtering feed fluid in a permeate and retained fluid filtration gap, the device comprising: (a) a filter holder member having a face main, the main face having a filter with (i) an active filtration area, (n) a peripheral region, and (m) a longitudinal axis subspecially perpendicular to the active filtration area; (b) a disk having opposing first and second main faces, the second main face (i) having an active area, (n) a peripheral region, and (m) a longitudinal axis substantially perpendicular to the active area; Defining the active area of the disc and the active filtration area of the filter the fluid filtration gap between them, passing the fluid coming from the fluid filtration gap through the active filtration area of the filter which is the permeate and not passing the fluid through the active filtration area of the filter that is retained; (c) rotatable means for rotating either the disc the filter around the respective longitudinal axis or to rotate both so that the disc and the filter rotate with respect to each other and a pumping action is created which tends to move the fluid in the filtration gap of fluid coming from near the longitudinal axis of the filter towards its peripheral region; (d) first feed means for feeding the feed fluid to the fluid filtration gap close to the longitudinal axis of the filter; and (e) second disk feed means for feeding the fluid adjacent the first principal face of the disk through the active area of the second face of the disk toward the fluid filtration gap. In another aspect this invention relates to a rotary disk filtering device for filtering feed fluid in one or more permeate and retained dilution filtration gaps, the device (a) comprising one or more filter holder members each having first and second main faces oppositely posned, each main face having a filter with (i) an active filtration area, (ii) a peripheral region, and (iii) a longitudinal axis substantially perpendicular to the active filtration area; (b) one or more discs that are installed on a rotating shaft and in alternate interleaving relation with the filter holder members to define a plurality of fluid filtration recesses, each disc having opposed first and second main faces, each main face having an active area and a peripheral region, the axis having a rotary longitudinal axis; defining each fluid filtration gap through the active area of one of the discs and the active filtration area of the adjacent filter, passing the fluid from each fluid filtration gap through the active filtration area of one or more filters that they are the permeate and not passing the fluid through the active filtration area of one or more filters that are retained; (c) rotating means for rotating the shaft so that one or more discs rotate with respect to the filters and a pumping action is created which tends to move the fluid in the fluid filtration recesses in a direction away from the longitudinal axis of the fluid. axis; (d) first feed means for feeding the feed fluid to each of the fluid filtration gaps close to the longitudinal axis of the shaft; and (e) second feeding means in at least one or more discs for feeding the fluid adjacent to the active area of the first principal face of the disc through the active area of the second major face of the disc to the fluid filtration gap defined by the second main face. In another aspect this invention relates to a rotary disk filtering device for filtering the feed fluid in one or more permeate and retained fluid filtration recesses, the device comprising: (a) one or more filter holder members having each of the first and second main faces posned opposite each other, each main face having a filter with (i) an active filtration area, (ii) a peripheral region, and (iii) a longitudinal axis substantially perpendicular to the active filtration area; (b) one or more discs that are installed on a rotating shaft and in alternate interleaving relation with the filter holder members to define a plurality of fluid filtration recesses, each disc having opposed first and second main faces, each main face having an active area and a peripheral region, the axis having a rotating longitudinal axis; defining each fluid filtration gap through the active area of one of the discs and the active filtration area of the adjacent filter, passing the fluid from each fluid filtration gap through the active filtration area of one or more filters that they are the permeate and not passing the fluid through the active filtration area of one or more filters that are retained; (c) rotating means for rotating the shaft so that one or more discs rotate with respect to the filters and a pumping action is created which tends to move the fluid in the fluid filtration recesses in a direction away from the longitudinal axis of the fluid. axis; (d) first feed means for feeding the feed fluid to each of the fluid filtration gaps close to the longitudinal axis of the shaft; and (e) second feeding means in at least one or more discs for feeding the fluid adjacent to the active area of the first principal face of the disc through the active area of the second major face of the disc to the fluid filtration gap defined by the second main face, the second feeding means comprising one or more holes through the disc, wherein substantially all of those holes in each disc are located at at least about 0.1R from the longitudinal axis of the shaft, wherein R is the equivalent circular radius of that disk. In another aspect, the invention relates to a method for reducing the tendency of a rotating disc and a filter in a rotary disc filtering device to be forced together by the pumping action caused by the rotation of the disc or filter during the process of filtration, the rotary disc filtering device comprising: (a) a filter holder member having a main face, the main face having a filter with (i) an active filtration area, (ii) a peripheral region, and (iii) ) a longitudinal axis substantially perpendicular to the active filtering area; (b) a disk having opposite first and second main faces, the second main face (i) having an active area, (ii) a peripheral region, and (iii) a longitudinal axis substantially perpendicular to the active filtration area; defining the active area of the disc and the active filtration area of the filter the fluid filtration gap between them; (c) rotating means for rotating the disc or the filter relative to each other, thus creating a pumping action that tends to move the fluid in the fluid filtration gap from near the longitudinal axis of the filter to its peripheral region; and (d) first feed means for feeding the feed fluid to the fluid filtration gap close to the longitudinal axis of the filter; the method comprising providing a second supply means in the disk for feeding the fluid adjacent to the first main face of the disk through the active area of the second face of the disk towards the fluid filtration gap. In another aspect, the invention relates to a method for reducing the tendency of a rotating disc and a filter defining a fluid filtration gap in a rotary disc filtering device to be forced together by the pumping action caused by the rotation of the disk during the filtering process, the rotating disk filtering device comprising: (a) one or more filter holder members each having opposite first and second main faces, each main face having a filter with (i) an area of active filtration, (ii) a peripheral region, and (iii) a longitudinal axis substantially perpendicular to the active filtration area; (b) one or more discs that are installed on a rotating shaft and in alternate interleaving relation with the filter holder members to define a plurality of fluid filtration recesses, each disc having opposed first and second main faces, each main face having an active area and a peripheral region, the ee having a rotating longitudinal axis; each fluid filtration gap being defined by the active area of one of the disks and the active filtration area of the adjacent filter; (c) rotary means for rotating the ee so that one or more discs rotate with respect to the filters and a pumping action is created which tends to move the fluid in the fluid filtration recesses in a direction away from the longitudinal axis of the axis; and (d) first feed means for feeding the feed fluid to each of the fluid filtration gaps close to the longitudinal axis of the shaft; the method comprising providing a second feeding means in one or more discs for feeding the fluid adjacent to the active area of the first main face of the disc through the active area of the second main face of the disc towards the fluid filtration gap defined by the second main face. The specific design of the rotary filtering device is not critical, any design can be used as long as the benefits of this invention can be achieved. Accordingly, this invention may be used with any of the rotary disc filtering devices, described, or otherwise referred to in the documents referred to herein, which include the patents and applications owned by Membrex, Ine. In the preferred embodiments, each disk is generally flat and has two main faces and a filter is "placed opposite" towards each main face of a disk, thereby forming two fluid filtration holes with each disk In other preferred embodiments, three or more fluid filtration gaps are defined by plurality of discs or liter holder members. In yet other preferred embodiments, the disks are installed on a vertical ee to rotate, the fluid filtration gaps are included within the body of the fluid to be filtered (whose fluid may be included within a housing), the periphery of the members of filter holders involve restraining restricting means for restricting the flow of retentate out of the fluid filtration recesses in the fluid body and the filter holder member has an opening through which the fluid to be filtered is passed to and in the recesses of fluid filtration. In still other preferred embodiments, one or more rotating discs has one or more slots in fluid communication in the fluid filtration gap. The term "spiral" can be defined in several ways but a simple definition is that a spiral is the trajectory of a point in a plane moving around a central point in the plane as it recedes from or advances towards the central point. A "slot" is generally an elongated, hollow depression, or cavity extending from the surface of the disc or filter to below the surface of the disc or filter, wherein the length of the slot is generally parallel to the surface. The "spiral slot" does not need to be a true spiral along the total length of the slot.

As used herein, the term "oppositely placed" means that, for example, two surfaces are on opposite sides of the same element, for example, the two main faces of a sheet of paper are placed opposite each other, or that two elements are oriented towards each other through some gap or boundary, for example, the surface of a disk and the surface of a filter on opposite sides of a fluid filtration gap (ie, defining a filtration gap of fluid) are placed opposite each other. The term "substantially parallel" means that the two lines or planes that are "substantially parallel" do not form an angle with each other greater than about 30 degrees ("substantially parallel" is also defined below). "Closely spaced" means that two lines or planes or elements are not so far apart that they can not interact or work together to perform a desired function. Accordingly, in the case of the disc and filter orientation surfaces, "closely spaced" usually means that those surfaces are no further apart than about 100 millimeters, and in that context, "closely spaced" is also defined below . In some embodiments, one or more discs and also preferably one or more filter holder members are "suspended from" one or more parts of the device that can be collectively considered as "the first member". One or more rotating members (one or more of the disk (s) and / or filter (s)) rotate during filtering. Accordingly, a "rotary suspension" must be used to rotatably suspend the first member with the rotary shaft carrying these one or more rotating members. The rotating suspension can be any suitable means, for example, bearings, lip seal, dynamic seals, bushings, gaskets or stuffing boxes. However, the rotating suspension will preferably be higher than the level of the fluid to be filtered, thus eliminating the need for rotary seals and allowing the use of a type of rotary suspension that is generally simpler, less expensive and less critical (for example, a simple rotating bearing). ). The term "suspension of" must be understood to include attaching to, securing to, depending on, and / or suspended from; it should also be understood to include cantilever suspension; and it should also be understood to include the suspension resulting from any spiral orientation (either vertical, horizontal or diagonal) of the discs and filters; and it should also be understood to include both direct and indirect suspension (e.g., wherein a first filter holder member is suspended directly from the first member and the second filter holder member is suspended directly only from the first filter holder member and not from the first member, in which case the second filter holder member is indirectly suspended from the first member). For a device in which the discs and filter holder members are suspended from the same unit member, it is clear that they are suspended from "the first member". However, for some devices, two or more parts (for example, plates, structural arms, gearbox, motor) of the device (some or all of which may or may not be held together) may constitute "the first member" . An indication of whether or not two or more parts of the device collectively constitute "the first member" is whether they can (but need not necessarily) be extracted together from one or more significant parts of the device (eg, the rest of the device or the rest of the housing or portion of the vessel of the device that holds the fluid to be filtered) to remove the disk and filter holder members together from the other parts of the device. Accordingly, if the discs and filter holder members can be removed together from the device by co-extracting one or more device parts from which the discs and filter holder members are suspended., that one or more device parts from which the discs and filter holder members in this device are suspended can collectively refer to as "the first member" and the discs and filter holder members in this device are "suspended from the first member". Also, in that device "the first member" is considered "removable". The "removal" of the first member may allow the filter holder members and disks to be removed as a unit, for example, for maintenance and without having to disassemble the rest of the device. There is another way to consider whether the discs and / or filter holder members are "suspended from the first member", which can be used, for example, for a device in which the discs and filter holder members are suspended from one or more parts of the filter holder. device and that one or more parts of the device are generally not removable from other significant parts of the device. Such a device, for example, may be one in which the discs and filter holder members are suspended from the upper part of a device and the upper part (which may comprise one or more parts) is non-removable from the rest of the device, which it includes the various legs on which it remains (for example, it remains in a lake or in another body of fluid). In this device, the discs and filter holder members are considered to be also "suspended from the first member" because the discs and filters are suspended all in a cantilevered manner in "generally the same direction" (because they are all suspended towards down from the top). The suspension address is the general direction of the suspension of the support member to the supported member, whose address ignores any bends or bends. By "generally the same direction" it is meant that the direction of suspension of the discs and the direction of suspension of the portafilter members are at no more than one acute angle to each other, ie, an angle less than 90 degrees, desirably less than 45 degrees, more desirably less than 30 degrees, preferably less than 15 degrees, and more preferably not at an angle to each other exceeding 5 degrees. The suspension of the discs or filter holder members of the first member is not inconsistent with the discs, the filter holder members, the assembly of the discs and filter holder members, and / or the shaft that carries the contact discs or stabilized when attached. or being annexed in some way directly or indirectly to another part of the device or to a part of the "natural vessel" (for example, the bottom of a lake) that retains the fluid to be filtered. One or more of the filters / filter holder members that define a fluid filtration gap can (but not necessarily) have restriction means to restrict (and also direct) the flow of retentate out of that fluid filtration recesses. in the body of the fluid. Without some means of restraint, the retentate leaving one or more fluid filtration gaps flows into the body or fluid more radially distant from the axis of rotation (longitudinal axis) than from the outer periphery of the disks and the filter holder members. The rotational speed component of the retentate moving radially out of the fluid filtration gap (s), whose rotating component is imparted by rotating one or more discs or filters, causes fluid in the body of the fluid radially out of the fluid filtration gap (s) rotate in the same direction as the discs or filters rotate. The rotation of this radially distant fluid, whose rotation can be quite vigorous, tends in turn to make it more difficult to perform the flotation of less dense materials or the settlement of denser materials in the same vessel, if such flotation is desired. The rotation of this radially distant fluid also tends to originate gas (for example, air) to be sucked into the fluid to be filtered. Consequently, it is generally desirable to control the flow of retentate effluent from the peripheries of the fluid filtration gaps. Such control can be performed by creating a barrier or dam near the outer periphery of the filter holder member (s) to significantly restrict the egress of retentate from the fluid filtration gap (s) in the liquid. radially distant. A complete barrier would avoid any retention derived from leaving the voids and would substantially prevent any rotation of the radially distant liquid. Because it is usually desirable to allow a retainer to exit the recess (s), the openings can be placed in the barrier or dam. Also, directing the flow retentate effluent against the direction of rotation will tend to counteract the rotating speed component and decrease the tendency of the radially distant fluid to mix or rotate. The means for directing the flow of retentate effluent may be openings or nozzles in or on the barrier directed against the direction of rotation. The openings or nozzles or other means can direct the retentate effluent in any other suitable direction. Using the barrier or dike tends to prevent undue agitation (eg swirling) of the fluid body and allows zones to be established at rest in the vessel, for example, to allow the flotation of less dense material and settlement of material more dense The restriction means may be thought of not only as to substantially decouple the flow pattern in the fluid filtration gap from the flow pattern of the feed fluid but also to decouple substi- tionally the pressure in the fluid filtration gap from the fluid. pressure in the body of the feeding fluid. Accordingly, the restriction means may allow the pressure in the fluid filtration gap (s) to be considerably higher than the pressure in the supply fluid body. Desirably, filter holder members are used that can be easily placed on or removed from their position with respect to the rotating discs to avoid the need to remove the discs from the shaft to allow removal of the filter holder members. Such easily removable filter holder members can have any shape but will generally be in the form of a D or circular in plan view. In any case, a cut-out may provide a clearance, for example, for the rotating shaft on which one or more disks are installed. Two liter-holder members generally in the form of a D can be placed in position (next to a disc) so that their straight sides are oriented towards each other, thus forming a generally circular assembly in this way. In that case, each member of the filter holder will have located in the center of its straight side a generally semicircular cutout for the suspended axis or sleeve. A generally circular, easily removable filter holder member will usually have a radial cutout extending from the periphery towards the center of the filter holder member to provide the necessary clearance for the shaft or sleeve. It does not matter that the shape of the filter holder member, two or more filter holder members can be mechanically connected to allow them to move as a unit (a filter holder member cartridge) in and out of position with respect to the discs. Other features, aspects and advantages of the invention will be apparent to one skilled in the art.

BRIEF DESCRIPTION OF THE INVENTION In order to facilitate the further description of the invention, the following drawings are provided in which: Figure 1 is an elevational view of a part of a device of this invention having two fluid filtration gaps and without the tank in which the body of feed fluid to be filtered is retained; Figure 2 is a partial elevational view showing a portion of the restriction means for restricting the flow of retentate out of the fluid filtration recesses; Figure 3 is a bottom-up view of a preferred rotating disc used in the device of Figure 1 showing the spiral grooves; Figure 4 is a cross-sectional view of the disc of Figure 3 taken along line 4-4 of Figure 3; Figure 5 is a schematic plan view of a preferred filter holder member having a generally circular periphery and an elongated cutout to provide clearance for the shaft; Figure 6 is a schematic plan view of a preferred filter holder member having a "D" shape and a central semi-circular cutout to provide clearance for the shaft; Figure 7 shows two of the filter holder members of Figure 5 placed together; Figure 8 shows a rotating shaft carrying five disks, each disc having two main faces positioned opposite each other and each having spiral grooves, the assembly of which can be used in a device having a multiplicity of disks and filters interspersed alternately; and Figure 9 shows a cartridge comprising five D-shaped filter holder members, the members of which are structurally connected so that they can move in and out of a rotary disk filtering device as a unit and which are also connected in a manner fluid so that the permeate coming from the five or the filter holder members flows towards two headboards and can be extracted through common nozzles. These drawings are provided for illustrative purposes only and should not be used to excessively limit the scope of the invention.

BEST MODES FOR CARRYING OUT THE INVENTION The design of the rotary filtering device of this invention is not critical and any design can be used on the condition that the device meets the requirements of the claims and offers the benefits of this invention. Accordingly, it is within the scope of this invention to have a rotating disc surface which itself is at least in part a filter surface although not preferred. It is also within the scope of the invention to have two closely spaced filtration surfaces positioned opposite each other that define the fluid filtration gap and that one or the other or both of the surfaces rotate, in which case one of the filtration surfaces would be considered to be It is the disc. According to the above, the use of the term "disc" does not exclude its orientation surface and helps to define the filtration gap that is also a filter surface. Similarly, the use of the term "filter" to refer to an element through which the permeate passes and whose surface is the second surface that is oriented and helps to define the fluid filtration gap does not exclude that the filter surface turn However, preferably only the disc rotates, the discs do not have filtration capacity, the filters (and filter holder members, which carry the filters) are not suspended in a rotating manner and therefore do not rotate, and all of the filtering capacity resides in the filters. If the filter that is oriented and helps to define the fluid filtration gap has some grooves or blades or other protuberances, the filter should be rigid enough to maintain the required shape. In that case, rigid filter materials such as metal (for example, metal s), ceramics, or glass may be suitable. However, it is preferred that the filter by itself does not contain any groove or blade and that the disk surface helps to define the fluid filtration gap containing any groove or blade that is used. The filter can be made from any material with the proviso that the filter can perform the functions required in accordance with this invention and that it is otherwise chemically and physically adequate under its respective operating conditions. According to the above, the filter can be polymeric, metallic, ceramic, or glass, and can be of any shape or shape. Accordingly, the filter can be formed of particles or of a film or fibers or of a combination of the three. The filter can be woven or non-woven. Generally, non-woven metal filters have certain advantageous characteristics compared to polymeric filters: they are easier to sterilize; They generally have chemical and thermal resistance; they can be cleaned more easily; and they have significantly better structural integrity and rigidity. If two or more filters are used in a device, they may be the same or different material and characteristics of filtration or screening. The filter used can be an asymmetric surface filter. An asymmetric surface filter is a filter whose two main faces have different pore size distributions such that the average or average pore size on one face is significantly smaller than the average or average pore size. Desirably, the asymmetric surface filter is oriented in a device of this invention with the face having the average or smallest pore size remaining facing the fluid filtration gap and the face with the average or average pore size more large being oriented away from the hole. A preferred metal filter of this type is the DYNALLOY fiber metal filter marketed by Fluid Dynamics of DeLand, Florida. The use of a metal filter can be advantageous if one or more electric fields are used in the device or if the filter carries a load. One or more electric fields can be applied in axial directions, or radial or non-radial non-axial directions. Fields can be useful to aid separation and can be applied using known technology. As used herein, "axial" means along or parallel to the rotational axis of one or more rotating members and "radial" means along or parallel to a radius of the plane of a disc or filter (i.e. perpendicular to the rotating axis of one or more members). The filter can be the result of direct or alternating voltage, for example, a high-frequency alternating potential. One or more fields can be applied in different directions, which together will result in a single applied field field. One or more fields can be varied as a function of time, for example, a radial field and an axial field in active / deactivated synchronization interleaved. Accordingly, the term "an electric field" as used herein should be understood to include all of the foregoing. The key function of a filter is to freely pass the permeate and not pass the retentate. To do that efficiently, the permeate must properly "moisten" the filter. A wetting indicator is the contact angle formed by a drop of permeate when placed on the filter surface (see U.S. Patent Nos. 4,906,379 and 5,000,848). Generally speaking, the smaller the contact angle, the greater the wetting and vice versa, the larger the contact angle, the lower the wetting. A drop of recovered permeate using a device of this invention will usually have a contact angle in the filter used in that device of less than 45 degrees, desirably less than 40 degrees, more desirably less than 35 degrees, more desirably less than 30 degrees, preferably less than 25 degrees, more preferably less than 20 degrees, and most preferably less than 15 degrees. The contact angle is measured using the method described in the U.S. Patent. No. 4,906,379 (see, for example, column 10, line 42 et seq.) and 5,000,848 (see, for example, column 12, line 46 et seq.) Because water is a high energy liquid, mainly due to the union of hydrogen, and because water is often a permeate in filtration processes, hydrophilic filters are preferred for use in the device of this invention. Filters whose surface energy has been increased to increase their hydrophobicity can be used. Accordingly, filters having a high surface energy (e.g., those of regenerated cellulose and those according to U.S. Patent No. 4,906,379) are a preferred class of filters. Such filters are moistened more easily by polar substances, such as water, but resist wetting by apolar substances such as organic compounds. Such high energy filter surfaces also have a reduced tendency to be soiled by materials having low energy properties, such as proteins and other organic substances. The preferred filters used in this invention of rotating disk are made in accordance with the U.S. Patent. No. 4,906,379 and are marketed by Membrex, Inc. under the trade name UltraFilic®. The UltraFilic® membrane is made of modified polyacrylonitrile (PAN) and its surface is modified chemically by being extremely hydrophilic ("hyperhydrophilic"). A device of this invention that uses a filter that allows to pass (permeate) but that rejects the oil will find a particular use to separate the water from the oil, for example, when cleaning oil spills or when recycling aqueous cleaning solution in a rinsing system of parts. Alternatively, a filter that is relatively hydrophobic (low surface energy) and that allows water to pass through and rejects water can be used. Other especially advantageous combinations of the device of this invention and filters having some inherent properties (for example, high rejection rate of some materials but fast and easy permeation of their co-components is in the feed fluid) will be apparent to those skilled in the art. in the matter. The use of such filters in combination with the device of this invention will provide advantages that may not be achievable without the combination. The filter can have pores of any size or shape provided they are suitable for the feed fluid and the permeate can provide the desired separation. The filter may have a narrow or wide distribution or other of pore sizes and shapes and may be asymmetric and used as an asymmetric surface filter. The filter can have a relatively accurate molecular weight cutoff. The filter matrix and particularly a polymeric filter matrix may also have binders attached thereto for selective sorption applications (e.g., ion exchange / sorption, affinity sorption and chelation). Suitable binders include any binder capable of attaching to the matrix or to a precursor or a maturity derivative. Preferred binders comprise (a) selective ion affinity groups (such as the chelator and box types) that selectively bind inorganic ions and (b) bio-selective affinity groups that selectively bind biologically active substances. The inventory of affinity binders is large and increases rapidly. Very often, such binders are derived from nature (ie, substances of biological origin) while others are completely or partially synthetic (ie, bio-mimic substances). Preferred binders, preferred methods for attaching binders to membrane filters, and preferred membrane filters are taught in the U.S. Patent. No. 4,906,379. Other binders and useful methods for attaching the binders to the filter will be known to those skilled in affinity sorption matters, chelation of immobilization of enzymes, and the like. As used herein, the term "selective sorbent binders" includes all the above binders. Almost any fluid to be filtered can be filtered using a device of this invention, but finds particular use in filtrate feeds having a high content of solids, mixed phase fluids and biological fluids. Fluids with a high solids content can be, for example, biological fluids, fluids containing affinity particles (eg, selective sorption affinity particles), ion exchange resin particles, catalyst particles, adsorbent particles, particles absorbers and particles of inert carrier. The inert carrier particles can themselves carry catalysts, resins, reactors, treatment agents (e.g., activated charcoal), etc. The mixed phase fluids include 1 fluid / solids, 1 liquid / 1 liquid and gas / liquid systems. The fluid may contain more than two phases. The liquid phases can be aqueous or non-aqueous or they can be one or more aqueous phases and one or more non-aqueous phases together. The phases can be immiscible, for example, two aqueous phases that are immiscible because each phase has a different solute. The fluid may have gaseous, liquid phases and solid phases. The reaction and / or thermal transfer may accompany the filtration process of this invention and take place inside or outside of a device of this invention. Biological fluids are fluids that originate from or contain materials that originate from biological organisms (for example, from animal or plant kingdoms) or components thereof, which include living and non-living things ( for example, virus). Accordingly, the term "biological fluids" includes blood; blood serum; plasma; spinal fluids; dairy fluids (for example milk and milk products); fluids containing hormones, blood cells, or genetic engineering materials; fluids from fermentation processes (including fermentation reactor broths and agents, intermediary, and product streams derived from beer brewing and winemaking, and wastewater treatment streams); fluids containing or comprising microbial or viral material, vaccines, plant extracts or vegetable or fruit juices (for example, apple juice and orange juice); fluids containing microorganisms (eg, bacteria, yeast, fungi, viruses); and else. The device is particularly useful with fluids containing pressure sensitive or shear sensitive components, for example, cells (blood cells, mammalian hybridomas, pathogens, for example, bacteria in a fluid sample that are concentrated to allow detection, etc. .). It is useful for filtering fluids containing drugs and precursors and derivatives thereof. It is useful for filtering organic compounds in general (including oils of all kinds, for example, petroleum oil and edible oil) as individual or mixed phases (e.g., oil / water). It is also useful for filtering fluids containing surfactants, emulsions, liposomes, natural or synthetic polymers, wastewater from deburring and clarification operations (for example, tumbling and rectification fluids), industrial and municipal wastewater and cleaning agents in based on aqueous and semi-aqueous solvents. A plurality of disks and / or a plurality of filter holder members, which carry the filters, can be used in a device according to this invention. Accordingly, it is within the scope of the invention to have a single disc placed between two filters, thereby defining two filtration voids. In such a device, one or both of the main faces of the disk would each desirably have at least one spiral slot. It is also within the scope of this invention for such a device to have various discs and filter holder members alternately interspersed, i.e., discs and filter holder members in alternating arrangement, so that the filtration gaps are defined. In that case, the discs could be installed on a common axis to rotate in unison and the permeate from the filters could flow to a common manifold for collection. In a device having a plurality of discs and filter holder members interleaved, each surface a fluid filtration gap defining a fluid filtration gap may have one or more spiral grooves. Regardless of which elements (ie, the filter (s), the disk (s), or combinations thereof) rotate, the rotation must be at a constant speed or at variable speeds and in a single address or in alternate directions. If two or more members rotate, they can rotate in the same or different directions and in the same or at different speeds. The rotating member (s) may periodically reverse their direction (s) of rotation (ie, oscillate). At least one of each disk and filter pair defining a fluid filtration gap must rotate with respect to each other. Therefore, the filter and disc that define a fluid filtration gap should not rotate in the same direction and at the same speed. Preferably the filter or filters (and therefore the filter holder member or filter holder members) are stationary and the disk or discs rotate and only in a single direction of rotation. Removal of the permeate that passes through the filters is simplified if the filter holder members are stationary during filtration. The disk (s) and / or filter (s) can (n) move axially (alternating motion) approximately perpendicular to the plane of rotation) whether or not he or she is (are) the element (s) rotating (s). The disk (s) and / or filter (s) can also be vibrated or oscillated to aid filtration. Each filter is desirably installed in a filter holder member, which functions to support the filter and / or to provide a collection network for the permeate. Such a support is desirable, particularly if the filter itself does not have substantial structural rigidity. Preferably, a network of permeate collection passages is placed in the filter holder member in fluid communication with the downstream side of the filter (which is oriented away from the fluid filtration gap) so that the permeate passing through the filter. filter flows to the permeate collection passages. Any method for installing the filter in the filter holder member can be used on condition that it does not excessively inhibit the operation of the device. Preferably, the method for installing the filter does not significantly reduce the active filtration area of the filter but such reduction may be necessary in some cases. The filter holder member can have any size or shape provided that the advantages of the invention are achieved. Two or more filter holder members can be installed in one plane to form a filter holder member assembly that helps define a fluid filtration gap. Accordingly, for example, two D-shaped members (with semicircular off-axis cuts, etc.) can be placed with their straight sides close to one of gold to define a filter holder member assembly having a circumferential outer periphery. Desirably, each of the one or more filter holder members defining a fluid filtration gap may have near its periphery restricting means to restrict (and also direct) the flow of retentate out of the fluid filtration gap in the body of the fluid. fluid. If the restriction means are sufficiently high (ie, they extend sufficiently far from the plane of the filter holder member, for example, perpendicularly or diagonally away from the plane of the filter holder member), the adjacent filter holder member can be approached or touched. In this case, the restriction means can be thought of as forming a wall separating a regime of fluid movement and more intense shearing (the fluid between the discs and the filter holder members, and the fluid between the peripheries of the discs and the discs). filter holder members and the inner surface of the restriction means) of a less intense fluid motion and shear regime (the remainder of the fluid body, including the radially distant volume of the outer surface of the restriction means and the axially remote volume of, ie, axially out or beyond, the two outer filter holder members). The restriction means may also be used to separate a region of higher pressure (an inner region whose outer limit is the restriction means and, for example the two outer filter holder members) of a lower pressure region (the region outside the inner region, that is, the body of fluid to be filtered). A higher pressure can develop in the fluid filtration gap for a given fluid by adjusting the geometry of the device and the rotating speed. The geometry of the device includes the size and shape of the two surfaces that define the gap, the smoothness of those surfaces, the width of the gap, whether there are slots or blades or other concavities or convexities on any surface, and. if it is the case, its number, size, shape and relative position. If the fluid in the appropriate parts of the regime of fluid motion and less intense circulation moves sufficiently slowly and if the fluid properties (eg, surface tension, viscosity and density) are satisfactory, flotation and settlement can be carried out in this regime. This is useful, for example, in the separation subsystem of an aqueous part rinsing system, where the oil extracted from the parts by the cleaning solution and particles (e.g., metallic filings) carried by the cleaning solution in the separation subsystem can be separated by flotation (oil) and by settling (metal filings) from the aqueous cleaner.

The design of restraint means (if used) is not critical and any configuration, shape, location, or size can be used as long as the restraint means can perform their intended function. Although the restriction means not attached to any filter holder member could be placed in the device (for example, a hollow cylindrical member interposed between the periphery of the filter holder members and the remainder of the fluid body to be filtered, i.e., between the periphery of the filter holder members and the cylindrical wall of the housing), it is preferable for the restriction means to be carried by the filter holder members (ie, by the liter holder members having the restriction means), for example, of so that the restriction means can be removed as a unit with the filter holder members. The restriction means not carried by the filter holder members (eg, a cylindrical wall) may be suspended from the first member or may be attached to another vessel wall (eg, the side wall or bottom of the vessel). The restriction means may comprise a circular rim or ditch located near the outer periphery of the filter holder member projecting a sufficient distance from the plane of the liter holder member member. Accordingly, the flange can be projected only in a direction away from the plane of the filter holder member (e.g., up) or it can project in both directions away from the plane of the filter holder member (i.e. both up and down). Desirably, the filter holder members will carry restraining means and those means will insulate the fluid substantially in the high-velocity zone from the fluid in the quiescent zone. Optionally compressible means can be used between the restriction means of a filter holder member and the appropriate portion of the adjacent filter holder member to provide a fluid tight seal. If the restriction means is carried by the filter holder (s), the restriction means may but need not be located at the periphery of the filter holder member (s); however, the restriction means must be radially distant enough to perform the desired function. For example, if the fluid filtration gap is 100 millimeters wide, each filter holder member can carry restriction means and those means can be projected above and below the plane of the filter holder member by approximately 50 millimeters. Alternatively, the restriction means could be projected 100 millimeters above the plane of the filter holder member and in no way below the plane of the port member af i 11 ro. In most cases, it is desirable to retain to remix with the remainder of the fluid body to be filtered. This remixing may occur, for example, in the fluid body to be filtered out of the retentate flow restriction means, or only before being fed into the fluid filtration gap (for example, in the annular region between the rotary disk axis and the sleeve supporting the filter holder members), or in the fluid filtration gap by itself. Such remixing is desirable for a variety of reasons, including avoiding the emergence of extreme concentration gradients and "internally washing with steam" the fluid filtration gap that solids or other materials that may otherwise tend to accumulate and clog or clog the filter. . If the restriction means prevent substantial re-mixing, it may be necessary to provide retentate flow effluent means (eg, openings) in the "inner wall" formed by the restriction means to allow the retentate to exit the high shear rate . It may also be desirable to provide retentate flow targeting means for directing the retentate flow leaving the high shear rate to counteract any undue agitation (e.g., the formation of vortices) of the liquid in the radially distant volume that would otherwise originate because of the rotation of the rotating members (usually the discs). According to the foregoing, openings may be provided in the inner wall formed by the restricting means may be biased against the direction of rotation of the rotating members or nozzles oriented against the direction of rotation. These openings and / or nozzles can also be oriented so that the flow of retentate outside them is at an angle to the plane of rotation (eg, perpendicularly) to achieve other flow patterns within the lower shear fluid regime. The restriction means for a fluid filtration gap will frequently block a significant portion of the nominal area occupied by the restriction means. Accordingly, the percentage of the nominal area blocked by the restriction means will frequently be at least 85%, usually at least 90%, desirably at least 92%, more desirably at least 94%, more desirably at least 95%, preferably at least 96%, more preferably at least 97%, more preferably at least 98% and sometimes as much as 99% of the nominal area occupied by the restriction means. In other words, the open area defined by the openings in the restriction means will often be less than 15%, usually less than 10%, desirably less than 8%, more desirably less than 6%, most desirably less than 5%, preferably less than 4%, more preferably less than 3%, most preferably less than 2% and sometimes less than 1% of the nominal area occupied by the restraint means .. For this purpose, the nominal area occupied by the means of restriction for a fluid filtration gap is taken as the inner periphery of the restriction means (which in the case of the cylindrical restraint means are its inner circumference) multiplied by the height of the fluid filtration gap. The height of the fluid filtration gap will be taken as the distance from the midplane of the disk to the median plane of the oppositely placed filter holder member defining the gap. The feed fluid can be introduced into the fluid filtration gap continuously or in batches. The permeate can be extracted continuously or in batches. The retentate containing one or more concentrated species from the feed fluid may be the desired product, for example, for testing. The permeate product can be the feed fluid from which the particulate or other matter that would interfere with the subsequent tests has been removed by the filtering device. The retentate and / or permeate test may be for the presence of or concentration of some chemical or biological species or for one or more physical or chemical properties (eg, pH, temperature, viscosity, reaction range, specific gravity, ion chloride, antibodies, bacteria, viruses and other microorganisms, for example, Cryp t ospori di um oo cyt is and Gi a rdi a cys ts, DNA fragments, sugars, ethanol and toxic metals, toxic organic materials and the like). Accordingly, a device of this invention may further comprise means for physically and / or chemically testing the retentate and / or the permeate, for example, for one or more of the species and / or properties (features) above. Any method can be used to place the fluid to be filtered in the one or more fluid filtration gaps but the fluid will desirably be placed in the gap close to the longitudinal axis, i.e. the rotating shaft. Therefore, for example, the feed fluid can flow through the rotating shaft or a sleeve around the shaft (forming an annular region between the shaft and the sleeve) and is transferred to the fluid filtration gaps through ports on the shaft or sleeve, or one or more voids may be immersed in a natural body of fluid (eg, a pond or a lake) or in a body of fluid contained in a vessel (or housing), or two or more of those and other schemes may be used. flow. In a particularly desirable configuration, the retentate leaving one or more fluid filtration recesses is recycled in the fluid filtration recesses. For example, the retentate leaving the fluid filtration recesses can be channeled to the annular region between (i) the rotating shaft by which the disks are rotated and (ii) a sleeve around the shaft that supports the filter holder members, whose annular region may be in fluid communication with one or more fluid filtration gaps. Suitable restriction and channeling means can be installed to achieve the recycling of the retentate to the fluid filtration voids, and some or all of the retentate leaving the fluid filtration voids can be recycled. Feed (from the body of fluid to be filtered) fresh (not recycled) can enter the fluid filtration gaps by any suitable means, which includes traversing the ports of entry in the sleeve (if a sleeve is used and it is connected fluidly with the fluid filtration recesses) or through an opening in one or more filter holder members (eg, the filter holder member further away from the first member) or by any combination of those and other means. Fresh feed and any recycled retentate may or may not be mixed before entering the fluid filtration recesses. For example, such mixing may originate in the annular region between the sleeve and the shaft or only before entering one of the fluid filtration voids.

The vessel or housing for retaining the fluid may be part of the device. The housing (which includes the lower part, upper part and / or sides) may be of any size or shape and any material provided that the housing does not adversely affect the performance of the device of this invention. Generally, the housing will not be larger than reasonably required (1) to accommodate and / or suspend the disk (s) and the filter (s), and (2) provide a body of fluid to be sufficiently filtered. large (if the housing is used to retain the fluid); and (3) provide sufficient volume for flotation and / or settlement (if flotation and / or settling are to be performed in the same vessel). A housing need not be used at all or the housing or part of its bottom, top, and / or sides may be opened and the device with the housing may be placed in a fluid body (eg, a lake, a tank fermentation) to produce a permeate and / or retained product, for example, for testing. Partial or complete immersion of the device may allow the fluid to flow into the fluid filtration gap. The pumping action of the device (for example, caused by the rotation of the device (s)) can also be used to move the supply fluid in the filtration gap from the fluid body of the a The device of this invention can be used in different ways, for example, to buffer a reaction (for example, by testing, or to produce a verifiable fluid from, the reaction medium in a reactor or a reactor effluent stream), or as an integral part of a reactor scheme (for example, to separate the catalyst from a reactor effluent stream for recycling to the reactor or for regeneration or to continuously extract the product and / or by-products and / or continuously replenish a reactor from cell culture, or in biological wastewater treatment (for example, to retain activated sediment used to assimilate organic matter)), or as part of a recovery scheme (for example, to separate products, by-products, contaminants, etc. coming from a reaction or process stream). The device can be located insitu in any type of process vessel (eg, reactor) or pipe (eg, reactor effluent pipe, or retrograde current pipe) for any purpose (eg, producing a test fluid) in where the filtration needs to be done continuously or intermittently. Although there are no theoretical upper or lower limits on the diameter of the discs and filters, due to the rotating speed, which can vary anywhere from below 100 rpm up to 1000 rpm or higher, and due to design, manufacturing and restrictions of cost, the rotating member (s) of the filtration device will rarely be more than one or two meters in diameter. According to the foregoing, in order to increase the capacity of a device of this invention beyond the capacity provided by the disks and filters by approximately one or two meters in diameter, it is preferred that the filtering capacity is increased by adding disks and / or Additional filters as required. Regardless of disk and filter diameters, capacity can always be increased by adding more disks and filters to a single device or by connecting two or more devices in series or in parallel. The discs and / or filter holder members can be installed in a plurality of different suspension means in a common housing, which are suspended from a common member (e.g., a top part), etc. Accordingly, for example, a housing for including the fluid body to be filtered could have two or more rotating axes therein, wherein one or both axes are suspended from the top or side of the device and each axle carries one or more discs, and / or one or more sets of filter holder members could be suspended from the top or side of the device. 'A frame (for example, an upper part installed on several legs to remain in a reaction vessel or a lake) could carry two or more rotating axes on which two different sets of discs are installed. The disk can be made of any material and have any design or shape provided it has the required physical and chemical properties so that it can perform its function in accordance with the present invention. Because the disk can be rotated in accordance with the present invention and because it is desirable that the disk does not deform during the filtering process, the disk requires a certain minimum structural rigidity. Also, the disk preferably must be relatively chemically inert to the feed fluid. Generally, the disc will be made of metal although other materials such as ceramics, glass, and polymers may be used. Preferably, the surface of the disc facing the fluid filtration gap, which includes the inner surface (s) of any groove in the disc, is relatively smooth (except for the presence of the second disc). feeding medium). Preferably, the surface of the filter, which includes any groove used in the filter, is relatively smooth. A rough surface favors the principle of turbulent flow in the fluid in the filtration gap at lower rotational speeds, whose flow is inefficient in energy and can adversely affect one or more components of the fluid to be filtered. Accordingly, desirably the fluid flow in the fluid filtration recesses is substantially non-turbulent, preferably essentially non-turbulent, and most preferably completely non-turbulent. It is surprising that despite the presence of the second feeding means, for example, the holes leading from one main face of the disc through the disc to the active area of the other main face of the disc defining the fluid filtration gap, would appear to stimulate turbulence in the fluid filtration gap, such second supply means are an integral part of this invention, do not destroy the substantially non-turbulent flow desired in the fluid filtration gap, and help to provide the benefits of this invention . Generally, the periphery of the disc and the filter and the filter holder member will be circular, although other shapes may be used. The center of the filter will desirably coincide with the center of the filter holder member, the center of the disk will desirably match the center of the filter and the centers will desirably extend over the rotary axis of the rotating element (s) and over the longitudinal axis of the disc (s) and member (s) of the filter holder. The peripheries of the disc and the filter holder member will usually be approximately the same radial distance from the rotary axis. Usually a disc surface will be oriented towards a single filter holder member and the peripheries of each will be approximately the same distance from the rotary axis. Preferably, the surface of the filter is substantially planar. Depending on the type of filter and its surface, the surface may have microconcavities and microconvexities; however, its presence is not inconsistent with the filter surface being considered substantially flat. Further, if the filter surface contains one or more slots and even if those slots occupy almost the entire surface of the filter and have depths of 5 millimeters or more, that still will not prevent the filter surface from being considered substantially flat. Similarly, the disc surface which helps to define the fluid filtration gap is preferably also substantially planar, and the presence of microconcavities, microconvexities, and grooves with depths of 5 to 10 millimeters or more will not yet prevent the surface of filter is considered substantially flat. Although the disc and filter surfaces are preferably flat (for example, to facilitate manufacturing), they need not be flat. For example, either or both may have axial cross sections that are conical, trapezoidal, or curved. In fact, any form can be used with the proviso that the benefits of this invention are still achieved. Because the width of the fluid filtration gap can vary radially (ie, according to the distance from the rotary axis, which is the longitudinal axis of the rotary axis, varies), the two surfaces defining the gap can, for example , to be closer to each other in their centers or in their peripheries. If both surfaces have the same cross-sectional size and shape, they can be oriented so that the width of the gap is constant, for example, where both disk and filter are conical and nested. Preferably the surface of the disc and the surface of the filter defining the fluid filtration gap will be "substantially parallel", ie the planes of the two surfaces will not meet at an angle to each other exceeding approximately 30 degrees, desirably 20 degrees, more desirably 15 degrees, preferably 10 degrees, and most preferably will not be at an angle with each other exceeding 5 degrees. Even if a member (disk or filter) is, strictly speaking, not flat (for example, disks and tapered filters), the member will still be considered to have a main plane of its general orientation, and it is that plane that should be used to determine whether the planes they are substantially parallel. A device according to this invention can be oriented horizontally, vertically or diagonally, that is, the rotary axis of the disk and / or rotary filter holder members (if any) can be horizontal, vertical or diagonal. In a vertically oriented device having a disk and a filter, the disk may be above the filter or the filter may be above the disk. Regardless of the number of discs and filters and the orientation of the device, it is desirable that the fluid filtration gap be kept filled with fluid during filtration. The rotation of the disc (s) and / or filter holder member (s) can be achieved using any direct or indirect means, for example, an electric motor, a motor driven by means of pulleys and drive belt or by transmission of gears, or a magnetic drive. Therefore, rotating members (for example, disks) do not need to be installed - 7! on an axis that rotates them. The axial translation of the disc (s) or filter holder member (s) and vibratory movement can be performed using known technology, in contrast to the cross flow filtration devices, the shear rate near the filtration surface and The transmembrane pressure or differential transmembrane pressure ("TMP") in a device of this invention can be made substantially independently of one another (although the fact that the filter used herein does not need to be a membrane, the term is used "transmembrane pressure" because it is a common term.) A filter system of this invention allows for precise control during separation and can be operated and controlled in a variety of ways, for example, for a given feed fluid, device geometry , filter, and rotational speed of the rotating member, the permeate flow can be controlled by a pump (for example, a pump Peristaltic extraction (measurement) of permeate and the concentration of retained volumetric concentration contoured by adjusting the feed rate at permeate flow rates. Control of the system can also be achieved with flow control valves and pressure control valves. Some of the advantages of this invention are made possible by the fact that the key operating parameters (shear rate, transmembrane pressure, and feed, retentate, and permeate rates) can be controlled independently and manipulated to a substantial degree. The control system for the filtering device for continuous or batch addition or extraction of the feed and / or permeate and / or retained fluid can be provided. The design of the peripheral equipment used with the filtering device is not critical. Existing technology should be used for the addition, collection, removal of the fluid, for the control system, the rotary drive means, etc. The design and selection of all this peripheral equipment is within the experience in the field.

Generally, the working pressure and transmembrane pressure in the device may be values that do not interfere with the filtration process or adversely affect the feed or product fluids. Accordingly, a transmembrane pressure can be used only slightly above atmospheric pressure or the transmembrane pressure can be substantially higher. Generally, lower transmembrane pressures are preferred because they tend to minimize solids formed on the surface of and within the filter. As well, lower operating pressures are generally preferred because they tend to make the equipment less expensive. However, in some cases it may be desirable to use higher operating pressures to aid filtration. For example, when carbonated beverages are processed, the working pressure must be kept high enough to avoid degassing. Higher pressures in the fluid filtration gap may also be desirable to help carry out the filtration. The higher pressure in the fluid filtration gap can also allow distribution with a vacuum pump to extract the permeate. It may also be desirable to use other forces, for example, electromotive force, to aid filtration in some cases. Desirably one or more spiral grooves are used on one or more of the surfaces defining each fluid filtration gap, and preferably the disk defining each gap rotates and carries one or more spiral grooves and the filter defining each filtration gap of fluid does not rotate and has no groove. A slot is a long narrow channel or depression. It can also be thought of as a concavity or elongated depression whose length extends in a plane parallel to the surface on which the groove is located. The term "spiral" can be defined in several ways but a simple definition is that a spiral is the trajectory of a point in a plane moving around a central point in the plane as it recedes from or advances towards the central point.

The spiral grooves used herein are preferably but need not be continuous. A surface can have more than one spiral, in which case the spirals can start and / or end at different distances from the center of the surface. If more than one spiral groove is used on a surface, the grooves can be crossed with each other and do not need to have the same shape or curvature or center point or transverse cross-sectional shape or area. The spirals do not need to end at the periphery of the surface. The spirals do not need to be on the rotating member (s). However, preferably, one or more spiral grooves used are located on the surface of the disk, the disk rotates, the feed is introduced to the fluid filtration gap at or near the rotating shaft, the grooves are true spirals, start close to the shaft rotating, they extend to the periphery of the disc, and do not cross each other. Preferably the grooves are oriented on the surface and the surface is rotated in one direction so that the outer peripheral end of each groove is pointing away from the direction of rotation. This tends to reduce the impact force of the fluid that leaves the slot. The slots desirably used herein are generally concave in their cross section and usually have no convexity at all. Preferably the internal surface of the cross section of the groove is a smooth continuous curve, for example, a cut of an ellipse or circle or combinations thereof. The slot may also have straight walls and be, for example, triangular, rectangular or square in its cross section. The cross section can also have straight and curved portions. A slot used herein is preferably of a constant width and depth but those dimensions may vary along with the length of the slot. The ratio of slot width to disc radius (or filter) will usually be from 0.001 to 0.6, preferably from 0.01 to 0.5, and most preferably from 0.01 to 0.4. The width may vary along with the length of the groove path so that the ratio of the groove width to radial location changes. Proportions of slot width to disk radius (or filter) outside the range of 0.001 to 0.6 may be used if the other parameters (eg, rotating speed) can be adjusted so that the benefits of this invention can be achieved. The separation between the two surfaces that define the filtration gap and the rotating speed affect the cleaning action or shear and, therefore, the flow. The effect of varying the gap, at least within a certain range, has a measurable but relatively small effect on the flow, ie, the relationship between the width of the gap and the wall shear (i.e., the shear rate in the membrane surface) is not strong. In any case, at the same point, the filtering surface and its opposingly placed disc will be too far apart for the rotation of at least one of the members in order to have some beneficial effect on the flow. On the other hand, due to the design tolerances, among other things, at the same point the two surfaces defining the filtration gap will be too close together to allow the rotation of one or the other or both members. According to the above, there is a useful working range of gap widths for any particular filtration device for a given supply fluid. The two opposingly placed surfaces defining the fluid filtration gap must be "closely spaced" and therefore the gap width will usually be within the range of 1 to 100 millimeters, frequently 1 to 50 millimeters, desirably 1 to 25 millimeters, preferably 1 to 15 millimeters, and very preferably 1 to 10 millimeters. Spacings outside the range of 1 to 100 millimeters can be used if the other parameters can be adjusted so as to obtain the benefits of this invention. The gap width for a given device may vary, for example, in the case where the disk (s) and / or filter (s) are not flat (for example, two conical surfaces pointing towards or away from the other) . In other words, the fluid filtration gap can vary radially. Such variation may be useful to help maintain the average shear stress constant as increases in feed viscosity as a result of concentrating one or more species (e.g., as in dehydration). The rotating speed affects the flow: the higher turning rates increase the cleaning action and the lower turning rates decrease the cleaning action. Any rotary speed can be used, that is, consistent with the design of the equipment and the sensitivity to shearing of the fluid being processed. The speed will usually be from 50 to 2000 rpm, desirably from 100 to 1500 rpm, preferably from 100 to 1200 rpm, and most preferably from 100 to 1100 rpm. Values outside the range of 50 to 2000 rpm can be adjusted provided that the benefits of this invention are still achieved. Other variables that affect the performance of the device of this invention 7 include, for example, the number of spiral grooves on the surface, length, width, and depth of the grooves, their cross-sectional shapes, the smoothness of the surfaces defining the filtering gap, and the parameters that define fluid rheology, which includes fluid viscosity, density, whether it contains particles (eg, cells), and the size, shape, and concentration of those particles. As explained in the U.S. Patent. No. 5,143,630, the angle subtended by a spiral groove (angle Y in Figure 1 of that patent) and the curvature of the groove (in relation to the angle T in Figure 2 of that patent) also affect performance. Still other variables that affect performance include the size, shape and location of any restraining flow restriction means, the number, size, shape and location of any retention flow addressing means, and either something or all the retentate effluent traversing the restriction means is recycled to the fluid filtration gap (s) and, if so, how that is done.

With this background, we turn to the accompanying drawings, which illustrate various embodiments of the present invention. With reference to Figures 1-4, the rotary disk filtering device 20 comprises the first plate 22, second plate 24, motor 26, shaft 28 having a longitudinal axis 30, sleeve 32, two filter holder members 34, and disk rotating 36 having first (upper) face 94 and second (lower) main face oppositely positioned 96. Nut 38 on the lower part of shaft 28 secures disc 36 to shaft 28. There are two fluid filtration gaps 40, which are parallel to each other. Each gap is defined by the filter 42, which remains in the circular plate 44 (which is the main part of the filter holder member 34), and the corresponding opposingly located main face of the disk 36. The device 20 can be placed in the top of a container (not shown) that retains the fluid to be filtered so that the second plate 24 remains on the supports through the upper part of the container. The upper level of the fluid body to be filtered would be below the lower face of the second plate 24. Accordingly, the rotary suspension 56, in which the shaft 28 rotates, would not need to be sealed against the fluid either. Each filter holder member 34 has a peripherally circumferentially located flange 46, which projects above and below the plate 44 of the filter holder member 34. The two flanges 46 on the adjacent filter holder members together form a path that is radially distant from the longitudinal axis 30. The compressible member (e.g., O-ring) 48 extends along that circular path and provides a substantially fluid-tight seal between the two flanges 46. Alternatively, the flange 46 on a filter holder member it can be designed to be nested within an adjacent filter holder member to provide a fluid tight barrier or seal in order to restrict the flow of retentate. The nesting mechanism can also be used to assist in the alignment of the filter holder members in the proper configuration during the assembly of the port to filter / disk assembly member or during the assembly of a filter holder member cartridge (described below). ). There is no need to use a compressible member (for example, the O-ring). During normal operation, the rotation of disk 36 will cause fluid circulation within each fluid filtration gap 40 and an outward pumping action (i.e., fluid movement in the recess from the longitudinal axis 30 towards the flanges). circumferential (peripheral) 46. Vary the pressure differences across (perpendicular to) the plates 44 as a function of the radial distance from the longitudinal axis will tend to cause the plates 44 to be deformed which in turn will cause the width of the fluid filtration gaps to vary radially. The projections 50 tend to avoid this bending (deformation) of plates 44 and therefore tend to keep the fluid filtration gap widths relatively constant. Alternatively, the projections may project radially from the sleeve 32 to thereby limit the deformation (bending) of the filter holder members. The drive column 52, which is part of the shaft 28, is connected at its upper end to the rotor of the motor 26 and is fixedly attached at its lower end to the rest of the shaft 28. The annular gap 54 extends between the axis 28 and sleeve 32. Because the sleeve 32 is centered with respect to the rotational longitudinal axis of the shaft 28 (ie, the shaft 30) and because the upper filter holder member 34 is connected and centered with respect to the sleeve, the The highest filter holder member is centered with respect to the rotary axis of the shaft and the disc. The lower filter holder member is aligned with and connected to the upper filter holder member and through this connection the upper filter holder member is connected (indirectly) to the sleeve 32. Therefore both filter holder members are connected to the "first member", which comprises plates 22 and 24. Sleeve 32 does not rotate. Accordingly, the filter holder members remain stationary and the disk rotates with respect to them when the motor 26 rotates the shaft 28 on which the disk is fixedly installed. The rotary suspension of the rotating member (the disc) from the "first member" is indicated by the reference number 56 and is above the normal level of the fluid to be filtered when the device 20 is placed in the body of the fluid to be filtered . The rotating suspension 56 is shown for convenience in Figure 1 as a rotating bearing installed on a plate (here, second lacquer 24); however, the rotary suspension will often (and sometimes preferably) be the bearing or rolling bearings in the gearbox, motor, or other drive means that rotate the drive column 52 (which is part of the shaft 28) and there will be no rotating suspension in any of the plates (that is, the drive column or shaft will go through a hole in the plates without bearing located at that point). The holes 58 in the side wall of the sleeve 32 (typically four holes, only two of which are shown, but can be used more or less) allow it to flow to the fluid in and / or out of the annular region or pocket 54 between the sleeve 32 and the shaft 28 coming from and / or towards the body of fluid in which the device is immersed. The annular region 54 is in fluid communication with the upper fluid filtration gap 40 and, through the means described below, is also in fluid communication with the lower fluid filtration gap 40. The centrally located circular opening 60 in each of the filter holder members 34 is defined by its inner edge 62. The shaft 28 extends through the central opening in the upper filter holder member 34, and the central opening 60 in the member of the lower filter holder 34 allows the fluid to be filtered to enter the upper and lower fluid filtration recesses 40 (during the filtration operation, the device 20 is immersed in the fluid to be filtered at a level below the second plate 24) . The fluid entering through the opening 60 in the lower filter holder member flows easily into the lower fluid filtration gap 40. The holes 64 are present in the inactive area of the disc 36 and the holes 66 (second feeding means) are present in the active area of the disc. The circle of dots 68 in Figure 3 indicates the inner periphery of the active area of the disk 36. In this mode, the active area of the disk is the same as the slotted area of the disk, since the slotted area is present on each side of opposite disc directly to the active filtering area of the respective filter. The semicircular openings in the circumferential rim 46 of the upper filter holder member 34 align with the identical openings in the circumferential rim 46 of the lower filter holder member 34 to form circular openings 70 in the "inner wall" formed when the two filter holder members are they extend adjacent to each other with the compressible member 48 in the middle as shown in Figure 2. These openings 70 allow the retentate to exit the fluid filtration gaps 40. There may be a gap in the compressible member 48 where each of the circular openings 70 are formed by the semicircular openings in circumferential flanges 46 so that the circular openings are not partially blocked by the compressible member 48 (which would otherwise bisect them horizontally). With reference to Figure 1, the inner edge 62 of the upper filter holder member 34 is attached to the sleeve 32. The attachment can be made using any suitable semi-permanent fastening means (eg, spikes, bolts, or threaded screws) or If desired, any permanent fastening means (eg, adhesive), although semi-permanent fastening means are preferred so that the upper filter holder member can be separated from the sleeve. The lower filter holder member 34 is held adjacent to the upper filter holder member 34 with the semicircular openings in the two filter holder members properly aligned by bolts. (not shown) passing through the corresponding bolt holes (not shown) located in the flange 46 of each of the two filter holder members. The openings in each of the two filter holder members that form circular openings 70 (Figure 2) are evenly spaced around the peripheral flanges 46. The edges 50 are also evenly spaced around each filter holder member 34. Figure 3 shows the lower face of the disc 36 of Figure 1, and Figure 4 is a cross-sectional view of the disc taken together with the line 4-4 of Figure 3. The disc 36 having the edge 72 is attached to the lower part of the shaft 28 (Figure 1) by the nut 38. the center of the disc 36 coincides with the center of each of the filter holder members 44 and the longitudinal axis 30 of the shaft 28 (Figure 1). The lower face of the disk (Figure 3 and the right side of Figure 4) and the upper face of the disk (the left side of Figure 4) each have 15 spiral grooves 74 equally spaced, spaced 24 degrees apart. The dotted line 76 indicates the lower part of one of the spiral grooves, which are separated from each other by spiral lands 78. The spiral grooves 74 terminate at their outer ends at the edge (periphery) 72 and at their inner ends at a central portion not grooved. The disk 36 is generally symmetric about the midplane 80, with the following principal exception. The cavity 82 ends before reaching the upper face of the disc 36 (the left side in Figure 4), otherwise the nut 38 would not be able to secure the disc 36 in the lower part of the shaft 28. On the lower main face of the disk (Figure 3), the circle of points 68 separates the central portion, which is the inactive or non-active area of the disk, from the active area of the disk, to which it contains the spiral grooves. also with reference to Figure 1, the upper active area of the disc (the active area on the upper main face) is positioned opposite the filter 42 on the upper filter holder member 44, and the lower active area of the disc (the active area on the lower main face) is positioned opposite the filter 42 on the lower filter holder member 44. On each of the two main faces, the active area is bounded near the longitudinal axis of the disk 30 by the imaginary circle 68 and by the outer peripheral region (edge) 72. The holes 64, which are within the inactive area of the disc, are not placed opposite either the upper or lower filter 42. The holes 66, which are within the active area of the disc, are positioned opposite both the upper and lower filters 42. (So as not to confuse Figure 4, the holes 66, which are shown in Figures 1 and 3, are not shown in Figure 4). Figure 5 shows a schematic plan view of a possible filter holder member having generally circular periphery 84 and radial cutout 86 terminating at its inner end at opening 88. Radial cutting allows the filter holder member to move in a generally direction perpendicular to the sleeve and the shaft on which the discs are installed, as described in the US Patent No. 5,254,250. Accordingly, each filter holder member can be detached from and removed from the alternate alternately interposed disc and filter holder assembly without having to remove the discs and filter holder members in alternating sequence. Figure 6 is a schematic plan view of another possible filter holder member used in the present invention. This D-shaped filter holder member has semicircular outer periphery 88, centrally located semicircular cutout 90, and straight portion 92. Two such D-shaped filter holder members can be installed as in Figure 7 with their straight sides close to contacting or continue to act with each other (a gap between the two straight sides would allow the detainee to flow from stage to stage). This D-shaped configuration also allows each of the filter holder members to be added or removed from the disk holder and filter holder assembly without having to remove any of the discs from the shaft. Therefore, the filter holder members need not be unitary members and any size and shape can be used in order to form the surface of the filter holder member that supports a filter defining a fluid filtration gap (with its disc placed opposingly). Figure 8 shows a multiplicity of discs 36 installed on the shaft 28. Each disc has several spiral grooves 74 in each of its first principal faces 94 and second major faces 96. Figure 9 shows the assembly (cartridge) 98 of five members of D-shaped filter holder of Figure 6. Each D-shaped member has a straight side 92, semicircular periphery 88, central semicircular cutout 90, first (top) main face 100, and second (lower) head face. The rotating shaft 28 will be located in the elongated central passage defined by the circular holes formed by the semicular cutouts 90 when a similar mirror image cartridge is brought near the cartridge 98 (straight sides 92 near the straight sides of the mirror image cartridge). ) in the assembled rotary disk filtering device. The five D-shaped filter holders of the cartridge 98 are mechanically connected to one another by the members 104 Two of the members 104 also fluidly connect the filter holder members to each other for the removal of the common permeate through the nozzles 106. The cartridge 98 can be installed in the rotary filtering device using bolts (not shown) that pass through the bolt holes 108 in two of the members 104. Each cartridge of the filter holder members can move as a unit in position with with respect to the discs that help to define the fluid filtration gaps. In these drawings, the devices shown are all vertically oriented (axis 28 is oriented vertically), the highest filter holder member that is attached (directly) to the "first member" (which comprises the first plate 22 and the second plate). 24), the lower and uppermost member is attached to a sleeve around the axis that rotates the disc. However, as previously noted, the device does not need to be oriented vertically. In addition, it does not need to be the first filter holder member in the assembly of the filter holder and disc members that is attached to the first member and one or more filter holder members do not need to be attached to such sleeve. E xemployment The tests were made using a device similar to that shown in Figure 1, a major difference being that the experimental device had two D-shaped filter members forming a substantially complete circular filter member surface above the rotating disc and two D-shaped filter members forming a complete essentially circular filter member surface below the rotating disk (see Figure 7). The outer diameter of each "circular" filter formed by the two D-shaped filters was 37,148 centimeters and the central circular clearance region (the opening in Figure 7 formed by the two semicircular cut-outs 90) of each was approximately 6.825 centimeters in diameter. The filters used in each of the four filter holder members were Membrex UltraFilic® filters. The pressure sensors were placed above and below the rotating disc under the respective filters at four different radial distances from the longitudinal axis (center or rotating shaft) of the shaft on which the disc was installed. These four radial distances were approximately 6.35 centimeters (an imaginary circle of 12.7 centimeters in diameter whose center is the longitudinal axis of the axis), 9.525 centimeters (an imaginary circle of 19.05 centimeters in diameter), 12.065 centimeters (an imaginary circle of 24.13 centimeters of diameter), and 15.24 centimeters from the longitudinal axis (an imaginary circle of 30.48 centimeters in diameter whose center is the longitudinal axis of the axis). Therefore, for example, the deepest part of the sensors (one under the filter above the upper fluid filtration gap and one under the filter below the lower fluid filtration gap) was 6.35 centimeters from the rotating shaft (or in an imaginary circle of 12.7 centimeters in diameter). Each disk had spiral grooves in each of its main faces, as shown in Figure 3, and rotated at 600 rpm, with water as the process fluid. The pressure in the holes caused the water to pass through the filters (permeate) and both the permeate and the retentate tried to leave the system. The width of the upper gap (between the upper part of the disc and the opposingly placed filter surface) was adjusted to 0.91 centimeters and the lower gap width (between the upper part of the disc and the opposingly placed filter surface) was adjusted to 0.20 centimeters . Each disc was approximately 34.93 centimeters in diameter. The central, non-slotted portion of the disk was approximately 6.99 centimeters in diameter. In other words, the spiral grooves began at about 6.99 centimeters in diameter (where the central portion was not grooved) and the grooves ended at the periphery of the disc (34.93 centimeters in diameter). Four holes (0.76 centimeters in diameter) were located symmetrically in the central, non-slotted portion of each disk at 90 degree angles to each other, with the north-south holes separating approximately 5.08 centimeters and the east-west holes separating 5.08 centimeters. . In some tests, the central holes were blocked. The different discs had different numbers and locations of holes 0.76 centimeters in diameter that extend from the active area (slotted spiral) of a main face of the disc to the active area. (slotted spiral) of the other main face of the disc. The deepest set of holes (when it was used) in the active area an imaginary circle was placed on top of the disk and it has a diameter of 8.15 centimeters. In other words, the deepest holes were found at a radial distance from the center of the disk (the rotating shaft) of approximately 4.06 centimeters. The other three sets of holes (when used) were forward imaginary circles that have diameters of 12.62 centimeters, 20.09 centimeters and 27.31 centimeters. The holes next to each imaginary circle were evenly spaced. In other words if five holes were used for one of the four imaginary circles, the holes were separated approximately 72 degrees (360 divided between Using the difference between the upper and lower pressures in each of the four radial positions and making various assumptions, calculated the external force of a system on each disk, the results are shown in the table below Test Hole Settings Pressure Difference (Upper Part Less Part Lower External Force (PSI)) Calculated (Pounds) A 12.7 cm A 19.05 cm A 24.13 cm A 30.48 cm without holes in the area 1.23 1.68 2.28 0.79 209.1 [9.3 * 107 di active; rubs the face [8.5 kPa] [11.6 kPa] [15.7 kPa] [5.4 kPa] bottom of the disc five holes of 8.15 cm from 1.12 1.15 1.06 0.64 128.8 [5.7 * 107 dynes] diameter; Retained line [7.7 kPa] [7.9 kPa] [7.3 kPa] [4.5 kPa] clogged five holes of 8.15 cm from 0.16 -0.15 0.01 0.26 5.4 [2.4 * 10 ° dynes] diameter [1.1 kPa] [-1.0 kPa] [ 0.07 kPa] [1.8 kPa] five holes of 20.09 cm 0.20 -0.31 -0.05 0 17 -3.7 [-1.7 * 10 dynes] in diameter [1.4 kPa] [-2.1 kPa] [-0.3 kPa] [1.2 kPa] five 8.15 cm holes; 0.15 -0.30 -0.05 0.26 -3.0 [-1.3 * 10th dynes] five holes of 20.09 cm; [1.0 kPa] [-2.1 kPa] [-0.3 kPa] [1.8 kPa] central holes clogged five holes of 8.15 cm; 0.17 -0.33 -0.06 0.23 -4.5 [-2.0 * 10th dynes] five holes of 12.62 cm; [1.2 kPa] [-2.3 kPa] [-0.4 kPa] [1.6 kPa] five holes of 20.09 cm: central holes clogged five holes of 8.15 cm; 0.10 -0.27 -0.04 0.16 -4.8 [-2.1 * 10th dynes] five holes of 12.62 cm; [0.7 kPa] [-1.9 kPa] [-0.3 kPa] [1.1 kPa] five holes of 20.09 cra five holes of 8.15 cm; 0.21 -0.14 0.04 0.25 7 8 [3.5 * 10 ° dynes] five holes of 27.31 cm [1.4 kPa] [-1.0 kPa] [0.3 kPa] [1.7 kPa] In test 1, the force that pushes the disc down towards the smallest gap is close to 8.9 * 107 dynes. The continuous operation would put under tension the bearings on which the shaft rotates. In addition, the friction of the disc against the lower filters would cause premature wear and possible failure and significantly reduce the filtration efficiency that occurs in the lower fluid filtration gap. Note that the downward pressure is very high despite the presence of the four holes in the central (inactive) area of the disk. In test 2, the addition of only five small holes in the active area of the disk but with the retained line obstructed (to prevent the extraction of the retentate), which in essence increases the back pressure on the system, still reduced the pressure towards down on the disk almost 40%. In test 3, which is the same as test 2, except that the disk retention line is no longer obstructed, the downward pressure on the disk has been reduced by only 2.4 * 10 'dynes. In other words, the addition of only five small holes with diameter of 8.15 cm (approximately 0.23R, where R is the radius of the disc), reduces the downward pressure from 9.3 * 107 dynes to 2.4 * 10d dynes a reduction of approximately 98%. In test 4, five holes in the active area of the disc are used again but they extend along an imaginary circle of 20.09 centimeters in diameter (a circle of 0.56R, where R is the radius of the disk). The pressure on the disc, instead of being a downward pressure, is now an upward pressure of approximately 1.7 * 106 dynes. In test 5, two sets of five holes each are used, one set of 8.15 centimeters (diameter) and the second set of 20.09 centimeters (diameter). The central holes in the inactive area become blocked. The upward pressure on the disc is approximately 1.3 * 106 dynes. In test 6, a third set of holes in the active area has been added to a diameter of 12.62 centimeters. The holes in the central area, inactive, become clogged again. The upward pressure on the disk is approximately 2.0 * 106 dynes. Test 7 is identical to test 6 except that the central holes are not clogged. The upward pressure on the disc is approximately 2.1 * 106 dynes, which is essentially the same as the upward pressure on the disc in test 6. This shows that the holes in the central, inactive, disc area do not difference some. In other words, the problem of non-uniform axial forces is not alleviated at all, by the use of holes in the central, inactive area of the disk. Test 8 has two sets in the active area of the disk, a set of 8.15 centimeters and the second set of 27.31 centimeters. The pressure on the disc is gently downwards, namely, 3.5 * 106 dynes. The comparison of this test with test 3 (downward pressure of 2.4 * 106 dynes) suggests that the addition of the second set of holes in the largest diameter makes a small difference. In general, the second feeding medium (holes) in the active area of the disk will generally be found next to an imaginary circle of at least about 0. IR where R is the radius (or equivalent circular radius, if the disk is not circular ), desirably next to an imaginary circle of at least 0.25R, and sometimes next to an imaginary circle of at least 0.5R or sometimes even 0.75R. The number of holes next to each circle will desirably be at least 2, preferably at least 3, and most preferably at least 5. The holes desirably evenly spaced next to the imaginary circle. The holes next to more than one imaginary circle should be used (for example, at approximately 0.25R and approximately 0.5R). It is surprising that the holes in the active area according to this invention can provide the benefits of this invention, in view of the teachings in the art that the active area of the disc (e.g., the slotted area) should not include concavity or roughness some purpose of trying to avoid turbulence.

Claims

CLAIMS Having described the invention as an antecedent, the content of the following claims is claimed as property: 1. A rotary disk filtering device for filtering feed fluid in a permeate and retained fluid filtration gap, characterized in that the device includes: (a) a filter holder member having a main face, the main face having a filter with (i) an active filtration area, (ii) a peripheral region, and (iii) a longitudinal axis substantially perpendicular to the active filtration area. to; (b) a disk having opposing first and second main faces, the second main face (i) having an active area, (ii) a peripheral region, and (iii) a longitudinal axis substantially perpendicular to the active area; Defining the active area of the disc and the active filtration area of the filter the fluid filtration gap between them, passing the fluid coming from the fluid filtration gap through the active filtration area of the filter which is the permeate and not passing the fluid 10 through the active filter area of the filter that is retained, the active disk area having at least one spiral slot in fluid communication with 15 the fluid when the fluid is in the fluid filtration gap, the spiral groove subtending an angle in Y in polar coordinates of at least 20 ten degrees on the second main face of the disk; half rotary to rotate half rotary to rotate either the disc the filter around the 25 respectively longitudinal axis or to rotate both so that the disc and the filter rotate with respect to each other and creates a pumping action that tends to move the fluid in the fluid filtration gap coming from near the longitudinal axis of the filter towards its peripheral region; (d) first feed means for feeding the feed fluid to the fluid filtration gap close to the longitudinal axis of the filter; and (e) second disk feeding means for feeding the feed fluid adjacent the first main face of the disk through the active area of the second face of the disk towards the fluid filtration gap. The device according to claim 1, characterized in that the rotary means includes an axis on which the disc is installed and the rotation of the shaft rotates consequently the disc, and the first feeding means includes means for introducing feed fluid into the shaft and passages through the shaft to drive the feed fluid in the shaft to the fluid filtration gap. 3. The device according to claim 1, characterized in that the rotating means includes an axis on which the disc is installed and the rotation of the shaft rotates consequently the disc, the shaft is surrounded by a sleeve, thus forming an annular region between the shaft and sleeve, and the first feeding means includes means for introducing feed fluid into the annular region and passages through the sleeve to conduct feed fluid in the annular region towards the fluid filtration gap. The device according to claim 1, characterized in that the active area of the disk is bounded by an inner boundary near the longitudinal axis of the second main face, the inactive area being the portion of the second main face between the longitudinal axis and the limit interior, and wherein the first feeding means includes at least one passage through the disc leading from an opening in the first main face to an opening in the inactive area of the second main face. The device according to claim 1, characterized in that the spiral slot subtends an angle Y in polar coordinates of at least forty-five degrees on the second main face of the disk. 6. The device according to claim 1, characterized in that the spiral slot subtends an angle Y in polar coordinates of at least ninety degrees on the second main face of the disk. The device according to claim 1, characterized in that the spiral slot subtends an angle Y in polar coordinates of at least one hundred and eighty degrees on the second main face of the disk. The device according to claim 1, characterized in that it also includes a plurality of the filter holder members and / or a plurality of the discs in interleaved relation and a plurality of fluid filtration recesses, each recess being defined by the active area of a disc and the active filtration area of a filter holder member. The device according to claim 8, characterized in that the rotary means rotates all the discs in unison or all the filters in unison. The device according to claim 1, characterized in that the width of the fluid filtration gap varies radially as measured from the longitudinal axis of the filter. The device according to claim 1, characterized in that the active filtration area and the active area of the disk are spaced separately not more than 100 millimeters and at an angle with each other not greater than 30 degrees. The device according to claim 1, characterized in that it also includes a first member in which the portafilter member is suspended directly from the first member. The device according to claim 1, characterized in that it further includes a first member and a plurality of filter holder members in which one of the filter holder members is suspended directly from the first member and the other filter holder members are suspended indirectly from the first member at Suspend from the first filter holder member. The device according to claim 1, characterized in that it further includes restricting means for restricting the flow of retentate out of the fluid filtration gap. 15. The device according to claim 1, characterized in that it includes a plurality of filter holder members, thereby helping to define a plurality of fluid filtration gaps, wherein said filter holder members are mechanically connected so that they can move as one. unit in and out of its normal operating position on the device. 16. The device according to the rei indication 1, characterized in that the filter holder member is generally D-shaped. 17. The device according to claim 1, characterized in that the filter holder member is generally circular and has a radial cut. The device according to claim 1, characterized in that the second feed means includes one or more holes through the disk, wherein each gap is located at least 0.1R of the longitudinal axis of the disk, where R is the equivalent circular radius of the disk. The device according to claim 1, characterized in that the second feeding means includes one or more holes through the disc, wherein each hole is located at least 0.25R of the longitudinal axis of the disc, where R is the equivalent circular radius of the disk. 20. A rotary disk filtering device for filtering the feed fluid in one or more permeate and retained fluid filtration recesses, including the di spos iti ve: (a) one or more filter holder members having each faces first and second main stations oppositely positioned, each main face having a filter with (i) an active filtration area, (ii) a peripheral region, and (iii) a longitudinal axis substantially perpendicular to the active filtration area; (b) one or more discs installed on a rotating shaft and in relation 10 interspersed with the filter holder members to define a plurality of fluid filtration gaps, each disk having principal faces first and 15 second positioned opposite each other, each main face having an active area and a peripheral region, the axis having a rotary longitudinal axis; 20 each fluid filtration gap is defined by the active area of one of the discs and the active filtration area of the adjacent filter, passing the fluid 25 from each fluid filtration gap through the active filtration area of one or more filters that are the permeate and not passing the fluid through the active filtration area of one or more filters that are retained; rotary means to rotate the shaft so that one or more discs rotate with respect to the filters and 10 a pumping action is created which tends to move the fluid in the fluid filtration gaps in a direction away from the longitudinal axis of the shaft; 15 first feed means for feeding the feed fluid to each of the fluid filtration gaps close to the longitudinal axis of the shaft; and second feed means in at least one or more discs having a spiral groove for feeding the fluid adjacent to the active area of the first major face of the disc. 25 disc through the active area of the second main face of the disk to the fluid filtration gap defined by that second main face. The device according to claim 20, characterized in that the shaft is surrounded by a sleeve, thus forming an annular region between the shaft and the sleeve, and the first feeding means includes means for introducing feeding fluid into the ring region and passages through the sleeve to conduct feed fluid in the annular region towards the fluid filtration gaps. The device according to claim 20, characterized in that the active area of the second main face of the at least one disk is bounded by an inner boundary near the longitudinal axis of the second main face, the inactive area being the portion of the face second main between the longitudinal axis and the inner boundary, and wherein the first supply means includes at least one passage through the disk leading from an opening in the first principal face to an opening in the inactive area of the second major face 23. The device according to claim 20, characterized in that the spiral slot subtends an angle Y in polar coordinates of at least forty-five degrees on the second main face of at least one disk. 24. The device according to claim 20, characterized in that the spiral slot subtends an angle Y in polar coordinates of at least ninety degrees on the second main face of at least one disk. 25. The device according to the rei indication 20, characterized in that the spiral slot subtends an angle Y in polar coordinates of at least one hundred and eighty degrees on the second main face of at least one disk. 26. The device according to claim 20, characterized in that it further includes a first member wherein one or more filter holder members are suspended directly from the first member. The device according to claim 20, characterized in that it further includes a first member and a plurality of filter holder members in which one of the filter holder members is suspended directly from the first member and the other filter holder members are suspended indirectly from the first member at Suspend from the first filter holder member. The device according to claim 20, characterized in that it also includes restricting means for restricting the flow of retention outside the fluid filtration gaps. The device according to claim 20, characterized in that it includes a plurality of filter holder members in which the filter holder members are mechanically connected so that they can move as a unit in and out of their normal operating position in the device. 30. The device according to claim 20, characterized in that each of one or more filter holder members are generally D-shaped. The device according to claim 20, characterized in that each of one or more filter holder members are generally circular and have a radial cut-out. The device according to claim 20, characterized in that the second feeding means includes one or more holes through at least one of one or more discs, wherein said hole is located at least about 0.1 R from the longitudinal axis of the shaft. , where R is the equivalent circular radius of that disk. The device according to claim 20, characterized in that the second feeding means includes one or more holes through at least one of one or more discs, wherein each hole is located at at least about 0.25R from the longitudinal axis of the disc. axis, where R is the equivalent circular radius of that disk. 34. A rotary disk filtration device for filtering feed fluid in one or more permeate and retained fluid filtration recesses, characterized in that the device includes: (a) one or more filter holder members each having major faces first and second positioned opposite each other, with each main face having a filter with (i) an active filtration area, (ii) a peripheral region, and (iii) a longitudinal axis substantially perpendicular to the active filtration area.; (b) one or more discs that are installed on a rotating shaft and in alternate interleaved relation with the filter holder members for 15 defining a plurality of fluid filtration gaps, each disk having first and second main faces positioned opposite each other, each main face having a 20 active area and a peripheral region, the axis having a rotary longitudinal axis; defining each fluid filtration gap through the 25 active area of one of the disks and the active filtration area of the adjacent filter, passing the fluid coming from the fluid filtration gap through the active filtration area of one or more filters which is the permeate and not passing the fluid to through the active filtration area of one or more filters that is retained; 10 defining the active area of the second main face of each of one or more discs having at least one spiral groove in communication with the fluid when 15 the fluid is in the filtration gap defined by the second main face, the spiral slot subtending an angle Y in polar coordinates of at least 20 ten degrees on the second main face of the disk; rotating means to rotate the shaft so that one or more discs rotate with respect to the filters and 25 creates a pumping action that moves the fluid in the fluid filtration gaps in a direction away from the longitudinal axis of the shaft; d) first feed means for feeding the feed fluid to each of the fluid filtration gaps close to the longitudinal axis of the shaft; E) second feed means in at least one or more discs having a spiral groove to feed the fluid adjacent to the active area of the first main face of the 15 disc through the active area of the second main face of the disk to the fluid filtration gap defined by that second main face, including the second 20 means of feeding one or more holes through the disk, wherein substantially all those holes in each disk are located at least about 0.1R from 25 the longitudinal axis of the axis, where R is the equivalent circular radius of that disk. 35. The device according to claim 34, characterized in that the active area of each main face of one or more discs defining a fluid filtration gap has at least one spiral groove in fluid communication with the fluid when it is in the recess of the fluid. fluid filtration defined by that main face. 36. The device according to claim 35, characterized in that at least one or more spiral grooves subtend an angle Y in polar coordinates of at least ninety degrees on the second main face of the disk. 37. The device according to claim 34, characterized in that the spiral slot subtends an angle Y in polar coordinates of at least forty-five degrees on the second main face of the disk. 38. The device according to claim 34, characterized in that the spiral slot subtends an angle Y in polar coordinates of at least ninety degrees on the second main face of the disk. 39. A method for reducing the tendency of a rotating disc and a filter in a rotary disc filtering device to be forced together by the pumping action caused by the rotation of the disc or filter during the filtering process, comprising the disc filtering device Rotating: (a) a filter holder member having a main face, the main face having a filter with (i) an active filtration area, (ii) a peripheral region, and (iii) a longitudinal axis substantially perpendicular to the area of active filtration; (b) a disk having opposite first and second main faces, having the second principal face (i) an active area, (ii) a peripheral region, and (iii) a longitudinal axis substantially perpendicular to the active area; defining the active area of the disc and the active filter filtration area the fluid filtration gap therebetween, the active area of the disc having at least one spiral groove in fluid communication with the fluid when the fluid is in the recess fluid filtration, subtracting the spiral groove an angle Y in polar coordinates of at least ten degrees on the second main face of the disk; (c) rotating means for rotating the disc or the filter relative to each other, thus creating a pumping action that tends to move the fluid in the fluid filtration gap from near the longitudinal axis of the filter to its peripheral region; and (d) first feed means for feeding the feed fluid to the fluid filtration gap close to the longitudinal axis of the filter; the method comprising providing a second disk feeding means for feeding the fluid adjacent the first main face of the disk through the active area of the second face of the disk towards the fluid filtration gap 40. The method according to claim 39 , characterized in that the second feeding means includes one or more holes through the disc, wherein each gap is located at least 0.25R from the longitudinal axis of the shaft, where R is the circular radius of the disc. 41. The method according to rei indication 39, characterized in that the second feeding means includes one or more holes through the disc, wherein each hole is located at least 0.50R from the longitudinal axis of the shaft, where R is the radius equivalent circular disk. 42. The method according to the rei indication 39, characterized in that the spiral slot subtends an angle Y in polar coordinates of at least forty-five degrees on the second main face of the disk. 43. The method according to the claim 39, characterized in that the spiral slot subtends an angle Y in polar coordinates of at least ninety degrees on the second main face of the disk. 44. A method for reducing the tendency of a rotating disc and a filter defining a fluid filtration gap in a rotary disc filtering device to be forced by the pumping action caused by the rotation of the disc or filter during the filtering process, the rotating disk filtering device comprising: (a) one or more filter holder members each having a first and second main faces positioned opposite each other, with each main face having a filter with (i) an active filtration area , (ii) a peripheral region, and (iii) a longitudinal axis substantially perpendicular to the active filtration area; (b) one or more discs installed on a rotary shaft and in alternate interleaving relation with the filter holder members to define a plurality of fluid filtration recesses, each disc having opposed first and second main faces, each main face having an area active, and a peripheral region, the axis having a rotary longitudinal axis; each fluid filtration gap being defined by the active area of one of the disks and the active filtering area of the adjacent filter, the active area of the second main face of each of one or more disks having at least one slotted spiral in communication fluid with the fluid with the fluid when the fluid is in the fluid filtration gap defined by the second main face, the spiral slot subtending an angle Y in polar coordinates of at least ten degrees on the second major face of the disk; (c) rotating means for rotating the shaft so that one or more discs rotate with respect to the filters and a pumping action is created which tends to move the fluid in the fluid filtration recesses in a direction away from the longitudinal axis of the fluid. axis; and (d) first feed means for feeding the feed fluid to each of the fluid filtration gaps close to the longitudinal axis of the shaft; the method comprising providing a second feeding means in at least one or more discs having a spiral groove for feeding fluid adjacent to the active area of the first main face of the disc through the active area of the second main face of the disc into the recess of the disc. filtration of fluid defined by that second main face. 45. The method according to claim 44, characterized in that the second feeding means includes one or more holes through at least one disc of one or more discs, wherein each of said holes is located at least 0.1R from the shaft. longitudinal of the at least one disk, where R is the equivalent circular radius of the disk. 46. The method according to claim 44, characterized in that the second feeding means includes one or more holes through at least one disc of one or more discs, wherein each of said holes is located at least 0.25R from the shaft. longitudinal of the at least one disk, where R is the equivalent circular radius of the disk.