Integrated prefilter for UF / MF membrane systems

Abstract

The filtration element (1) includes a filtration membrane (3) enclosed within a housing (2). The element has openings for removing filtrate and concentrate. A filter (11) is disposed within the element (1) at an opening (6) in the housing (2) for introducing feed into the interior volume (20) of the filtration element (11). Alternatively, the filter (11) may be positioned within an end cap (7) associated with such opening. Pre-filtration is thus performed within the filtration element 1 itself, rather than as a separate upstream operation. The presence of the filter (11) does not significantly increase the pressure drop across the filtration module. Flocculated particles and other debris that accumulate on the membrane can be easily removed by backwashing, despite the presence of the filter (11).

Description

[Technical Field]

[0001] Described herein are ultra- or microfiltration (UF / MF) modules and filtration systems using them, particularly modules with integral pre-filters. [Background technology]

[0002] Several patents, patent applications and publications are cited in this description in order to more fully describe the state of the art to which this invention pertains, and the entire disclosure of each of these patents, patent applications and publications is incorporated herein by reference.

[0003] Microfiltration and ultrafiltration systems are used in utility and industrial settings to purify fluids or recover materials from fluid streams. The most important application is water purification by treating process streams such as industrial waste, seawater, groundwater, sewage, and wastewater from sewage treatment plants. Other industrial applications include the purification and / or concentration of dairy products, fruit juices, and other beverages, enzyme recovery, and dialysis.

[0004] Both microfiltration and ultrafiltration processes operate by passing a feed fluid through a porous membrane that retains high molecular weight and / or particulate matter. This produces a purified filtrate stream and a separate concentrate stream containing the filtered material. Microfiltration and ultrafiltration are generally distinguished by the size of the membrane pores. Microfiltration membranes are typically used to remove particulate matter between 0.1 and 2 micrometers in size, which is small enough to remove larger microbial matter, such as some bacteria. Ultrafiltration can remove matter as small as 0.005 micrometers, small enough to separate a wider range of microorganisms, including viruses and other pathogens, as well as macromolecules, nanoparticles, proteins, biological cell debris, and more.

[0005] The membranes used for industrial-scale microfiltration and ultrafiltration are most often hollow fiber membranes, although other types, such as spiral membranes and tubular membranes, can also be used. Membranes are susceptible to fouling and damage from larger particles. Therefore, larger particles must be removed from the incoming feed stream. In industrial and wastewater treatment environments, this is accomplished using a separate prefilter system upstream of the microfiltration / ultrafiltration system. For example, Chinese Patent Application Publication No. 217312781 describes a sewage ultrafiltration device for environmental protection engineering. The device includes a two-piece shell, with a filter screen installed on the inner wall of one piece of the shell.

[0006] Large-scale installations require a significant number of microfiltration and ultrafiltration modules and a corresponding number of separate prefilters. Therefore, the prefilter system occupies a large footprint and represents a significant capital expense. A separate prefiltering system requires a separate maintenance system and operating system, imposing significant additional operating costs and requiring additional resources. Prefilters are typically mesh or disc filters that are often not chemically cleaned. Losses of water or other feed fluids are observed in the prefiltering operation. Significant savings in capital and operating costs can be achieved if the separate prefiltering system is made smaller or even eliminated. Summary of the Invention [Problem to be solved by the invention]

[0007] Clearly, there remains a need for improved prefiltration devices, systems, and methods in microfiltration / ultrafiltration processes. [Means for solving the problem]

[0008] Accordingly, there is provided herein a filtration assembly 100 comprising a filtration element 1, said filtration element 1 comprising: a) a housing 2 enclosing an internal volume 20 of a filtering element 1; b) at least one microfiltration or ultrafiltration membrane 3 disposed within the interior volume 20 of the housing 2; c) at least one outlet 4 for removing filtrate from the filtration element 1; d) at least one housing inlet 6 in the housing 2 for introducing a feed fluid into the filtration element 1; e) for at least one housing inlet 6, an associated inlet end cap 7 attached to the housing 2 and in fluid communication with the housing inlet 6 of the housing 2, the inlet end cap 7 having an opening 8 for receiving a supply fluid and defining a flow path for the supply fluid from the opening 8 of the inlet end cap 7 to the housing inlet 6 of the housing 2; f) for at least one housing inlet 6 having an associated inlet end cap 7, an associated filter 11 disposed (i) within the housing inlet 6, or (ii) within the associated inlet end cap 7 and in the flow path of the supply fluid from the opening 8 in the inlet end cap 7 to the associated housing inlet 6 in the housing 2.

[0009] In some preferred embodiments, the nominal aperture size of the filters 11 is in the range of 5-500 μm. In other preferred embodiments, the feed fluid is in fluid communication with the housing inlet 6 and the associated filter 11 is located (i) within the housing inlet 6 or (ii) within the housing 2 in the flow path of the feed fluid to the associated housing inlet 6.

[0010] Further, in this specification, A plurality of optionally cylindrical filtering elements 1 arranged in parallel, each of said filtering elements 1 comprising: a housing 2 enclosing an internal volume 20; a plurality of membranes 3 disposed within the interior volume 20, said membranes 3 being selected from the group consisting of microfiltration, ultrafiltration, nanofiltration, and reverse osmosis membranes, said membranes 3 dividing the interior volume 20 into a feed region and a filtrate region; a housing inlet 6 for introducing a feed fluid into the feed region of the filtration element 1; a housing outlet 4 for removing filtrate from the filtrate region of the filtration element 1; a supply fluid line 75 (synonymously and interchangeably referred to herein as a "supply and return header 75") including distribution conduits and a plurality of manifold or distributor outlets (the terms "manifold," "header," and "distributor" are synonymous and used interchangeably herein); There is further provided a filtration system 100 comprising a plurality of optionally cylindrical filtration elements 1, each of the plurality of filtration elements 1 being associated with a particular manifold outlet such that the plurality of membranes 3 within the filtration element 1 receive a feed fluid from the particular manifold outlet, and at least one filter 11 being positioned along a feed flow path between the membranes 3 within the housing 2 of the filtration element 1 and the associated manifold outlet.

[0011] In this device, preferably each filtration element 1 is associated with at least one filter 11 located along the feed flow path between the membrane 3 within the housing 2 of that filtration element 1 and the associated manifold outlet. Preferably, the nominal size of the apertures of the filters 11 is in the range of 5 to 500 μm.

[0012] The filtration elements described herein offer several important advantages: Pre-filtration occurs within the filtration element itself, rather than in some separate upstream operation. This allows for the reduction in size, if not complete elimination, of a separate upstream pre-filtering system, thereby substantially reducing capital and operating costs.

[0013] Surprisingly, the presence of the filter does not result in a significant increase in pressure drop across the filtration module, including the filter and associated components designed to hold or mount the filter within the filtration element, so operating pressures are not significantly affected and the pumping equipment does not need to be oversized to accommodate the filter.

[0014] Another advantage is that agglomerated particles and other debris that accumulate on the membrane can be easily removed by backwashing, despite the presence of a filter. More specifically, it has now been unexpectedly discovered that agglomerated particles that detach from the membrane 3 during backwashing readily break down under backwash conditions to form smaller particles that easily pass through the filter 11 and exit the filtration element 1. Debris is also removed from the filter 11 during the backwashing process, allowing for simultaneous backwashing of both the prefilter and the microfiltration or ultrafiltration membrane 3, thereby enabling further reductions in operating costs. The integral prefilter may also be chemically cleaned, if desired, simultaneously with routine membrane cleaning, thus providing a process that does not require additional resources.

[0015] Further provided herein are filtration assemblies including at least one filtration element 1, filtration systems including an array of a plurality of filtration assemblies, preferably an array including at least one column, and processes for filtering a feed fluid using the filter elements, assemblies, and systems described herein.

[0016] The advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and objects attained by its uses, reference should be made to the drawings which form a further part of this specification and to the accompanying descriptive matter which illustrates and describes one or more preferred embodiments of the invention. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a partial cross-sectional perspective view of a filtration assembly described herein. [Figure 2] FIG. 2 is an enlarged cross-sectional front view of a detail of a filtration assembly described herein. [Figure 3] FIG. 2 is a partial cross-sectional enlarged perspective view of an inlet end cap attached to a housing for use in a filtration assembly described herein. [Figure 4]FIG. 1 is an end view of a filtration system including multiple filtration assemblies arranged in a row. [Figure 5] FIG. 1 is a perspective view of a filtration system including multiple filtration assemblies arranged in a row. DETAILED DESCRIPTION OF THE INVENTION

[0018] As used herein, the term "feed fluid" refers to a fluid introduced into a filtration element for impurity removal. The term "filtrate" (or "permeate") refers to a fluid that has passed through the discriminant layer of a microfiltration or ultrafiltration membrane within a filtration element and contains a lower concentration of impurities than the feed fluid. The terms "reject" and "retentate," which are synonymous and used interchangeably herein, refer to the portion of the feed fluid that has not passed through (i.e., is rejected by) the discriminant layer of a microfiltration or ultrafiltration membrane and therefore contains a higher concentration of impurities than the feed fluid.

[0019] Referring now to the drawings, in which like reference numerals indicate corresponding structure throughout the figures, and particularly to FIG. 1 , a filtration assembly 100 includes a filtration element 1, which in turn includes a housing 2, which encloses an interior volume (generally designated by reference numeral 20) of the filtration element 1. Referring now to FIG. 2 , microfiltration or ultrafiltration membranes 3 are disposed within the interior volume 20 of the housing 2. These membranes 3 may be embedded in each end of the potting 10 or may otherwise be secured by other suitable means. These membranes 3 divide the interior volume 20 into a feed region and a filtrate region. A feed fluid becomes filtrate upon passing through at least one of the membranes 3.

[0020] With continued reference to FIG. 2 , housing 2 includes housing inlet 6 for introducing a feed fluid into interior volume 20 of filtration element 1. The terms “inlet” and “outlet” are generally used herein to indicate the direction of indicated fluid flow into and / or out of filtration element 1 during normal operation, i.e., during the time when feed fluid is being fed into filtration element 1 to remove impurities to produce filtrate and rejects. Thus, in the particular embodiment shown in FIGS. 1-3 , housing inlet 6 is the opening through which feed fluid is introduced into housing 2 during normal operation, and outlets 4 and 5 are the openings through which filtrate (via outlet 4) and concentrate (via outlet 5) are removed from filtration element 1 during normal operation. Fluid may flow in the opposite direction during other modes of operation, such as backwashing and / or cleaning. Thus, during backwashing and / or cleaning, fluid may be introduced into filtration element 1 through outlets 4 and / or 5 and withdrawn from housing 2 through housing inlet 6.

[0021] 1 and 2, the primary flow direction through filtration element 1 during normal operation is generally upward, with feed fluid introduced into the bottom of filtration element 1 through housing inlet 6, concentrate removed from the top of the filtration element through outlet 5, and filtrate removed through outlet 4 of housing 2, preferably at or near the top, as shown in FIG. 1. If desired, filtration element 1 can be inverted so that housing inlet 6 is at the top and outlet 5 is at or near the bottom of housing 2 to create a generally downward direction of flow through filtration element 1. As described more fully below, inlets for feed fluid may be provided at both the top and bottom ends of filtration element 1.

[0022] If present, the inlet end cap 7 is directly or indirectly attached to the housing 2, preferably attached and sealed directly around the housing inlet 6 of the housing 2 via welding, adhesive bonding, gaskets, various mechanical means, and / or other methods of creating a seal. Similarly, regardless of whether the inlet end cap 7 and the housing inlet 6 are directly or indirectly attached, the inlet end cap 7 is in fluid communication with the housing inlet 6 of the housing 2. In this regard, the two indirectly attached components may be joined, for example, via a length of tubing or by another connector known in the art. The inlet end cap 7 has an opening 8 for receiving a feed fluid from an external source (not shown). The inlet end cap 7 defines a flow path for the feed fluid from the opening 8 in the inlet end cap 7 through an opening 21 in the inlet end cap 7 and into the housing inlet 6 of the housing 2. Referring to FIGS. 2 and 3 , arrow 19 indicates the direction of flow of the feed fluid through the housing inlet 6 within the housing 2 in this particular embodiment.

[0023] A preferred inlet end cap 7 is a T-piece, as shown in FIGS. 1-3 . T-piece 7 includes a hollow body 23 defining a branched internal flow path for feed fluid to flow from opening 8 to both outlet 18 and opening 21. Opening 21 is in fluid communication with housing inlet 6 of housing 2. Opening 21 in the illustrated embodiment is fitted with filter 11, which is in the flow path of feed fluid entering housing inlet 6 of housing 2. Although not shown, it is contemplated that filter 11 may alternatively be located within or upstream of opening 8, with similar beneficial effect. During operation, at least a portion of the feed fluid flows from T-piece 7 through opening 21 and into housing inlet 6 of housing 2 of filtration element 1. A portion of the feed fluid entering opening 8 of T-piece 7 may additionally flow through T-piece 7 and exit T-piece 7 through outlet 18, from which it may enter, for example, a corresponding T-piece 7 of an adjacent filtration element 1 (as shown in FIG. 5 ). In such an embodiment, the filter 11 may be located downstream of the T-piece 7, for example at the outlet 18 or at the connection between the outlet 18 and the opening 8 of the adjacent filter element 1.

[0024] Filter 11 is preferably positioned within housing inlet 6 or in inlet end cap 7 (as shown in Figures 2 and 3) and within the flow path of the feed fluid within housing 2 to housing inlet 6. The orientation shown in Figures 2 and 3 is a preferred orientation in which filter 11 is oriented transverse to the direction of feed fluid flow through housing inlet 6 of housing 2. Filter 11 may alternatively be oriented at an angle to the direction of feed fluid flow through housing inlet 6, provided that feed fluid entering housing inlet 6 passes through filter 11.

[0025] Filtration element 1 further includes at least one outlet for removing filtrate from filtration element 1 and may include a separate outlet for removing retentate. In the particular embodiment shown in Figures 1-3, separate outlets 4 and 5 are provided. Depending on the mode of operation (outside-inside mode or inside-outside mode), outlets 4 and 5 may each be either a filtrate or a concentrate removal outlet, provided that one is a filtrate removal outlet and one is a concentrate removal outlet. Outlet 4 is preferably a filtrate removal outlet, and outlet 5 is preferably a concentrate removal outlet.

[0026] 1 , outlet 5 is disposed on an optional second end cap 9 attached to housing 2 and provides a flow path from the top opening of housing 2 to outlet 5 of end cap 9, through which filtrate or concentrate, preferably concentrate, is removed from interior volume 20 of housing 2. Second end cap 9 is preferably sealed around the top opening of housing 2 via welding, adhesive, gaskets, various mechanical means, etc., in the same manner as described with respect to inlet end cap 7. Similarly, outlet 4 may be disposed on optional outlet end cap 9.

[0027] A preferred outlet end cap 9 is a T-piece (as shown in FIGS. 1, 4, and 5) that includes a hollow body defining a branched internal conduit having an outlet 5, an inlet for receiving filtrate or concentrate from an opening in the housing 2, and a second inlet 15 opposite the outlet 5 for receiving fluid from the T-piece outlet end cap 9 of an adjacent filtration element 1 or other source. The branched internal conduit defines a flow path from the top opening of the housing 2 to both the outlet 5 and the second inlet 15. During operation, filtrate or concentrate, as the case may be, may exit the interior volume 20 of the housing 2, pass through the top opening of the housing 2, through the T-piece outlet end cap 9, and from the T-piece outlet end cap 9, through the outlet 5, and from there, into the second inlet 15 of a corresponding T-piece outlet end cap 9 of an adjacent filtration element 1, for example (as shown in FIG. 5).

[0028] Filter 11 preferably has a nominal opening size of 5 to 500 μm (approximately 35 openings per linear inch or greater). The "nominal" opening or aperture size is that reported by the filter manufacturer. To avoid creating an unnecessarily large pressure drop while still removing particles of the most frequently encountered size, filter 11 preferably has a nominal opening size of 50 to 300 μm (approximately 270 to 50 mesh), particularly 88 to 300 μm (approximately 170 to 50 mesh). Filter 11 is preferably a screen, particularly a mesh screen, the materials of construction of which can vary widely, provided that the screen is dimensionally stable in the feed fluid and under the pressure conditions encountered during operation. Metal mesh and hydrophobic organic or inorganic polymer mesh screens are particularly suitable.

[0029] To minimize pressure drop across filter 11, the surface area of ​​filter 11 is preferably at least 40%, at least 60%, at least 75%, or at least 80%, and up to 100% or more, of the surface area of ​​housing inlet 6 of housing 2. Filter 11 may include a screen attached to a frame or other support. For purposes of determining surface area, the surface area of ​​any frame or support is not counted in the filter surface area.

[0030] Again, when more than one filter 11 is present in a filtration element 1 or filtration system 100, the materials from which they are made, their nominal opening sizes, and their surface areas are independent and may be the same or different. Furthermore, filters 11 may be positioned in one or more of the locations described herein, as appropriate.

[0031] The embodiment shown in Figure 2 includes a preferred feature, filter mount 12, adapted to receive and secure filter 11 in place. In the embodiment shown in Figure 2, filter mount 12 is a mounting ring that is secured to inlet end cap 7 in a preferred position within opening 21. In this position, filter 11, when mounted in filter mount 12, is oriented transverse to the direction of feed fluid flow through housing inlet 6 of housing 2.

[0032] Alternatively, filter mount 12 and / or filter 11 may be disposed within housing inlet 6 of housing 2, again preferably oriented transverse to the direction of feed fluid flow through housing inlet 6 of housing 2. Positioning filter mount 12 and / or filter 11 elsewhere within end cap 7, such as within opening 8 in end cap 7, is also within the scope of the preferred embodiment where filter 11 is positioned upstream of housing inlet 6 of housing 2.

[0033] The filter mount 12 may be secured in place on the inlet end cap 7 and / or within the opening 6 of the housing 2 by any suitable means, such as via adhesive, welding, via a mechanical connector (such as a screw mount or bayonet mount), or alternatively may be formed integrally with the inlet end cap 7 or housing 2 as the case may be.

[0034] Filter 11 is most preferably removably mounted to filter mount 12 or other mounting (if used) or directly to housing 2 or inlet end cap 7 of filtering element 1. Preferably, filter 11 and the structure to which it is mounted (i.e., a mounting such as filter mount 12, housing 2, or inlet end cap 7) have interfacing devices for mounting and securing filter 11 in place. For example, interfacing devices may be provided that together form a bayonet mount, screw mount, snap or friction mount, magnetic mount, or other convenient device for mounting and securing filter 11 in place.

[0035] If the feed fluid is introduced into the filtration element 1 from that direction, a separate filter mount 12 and / or filter 11 may be secured in a similar manner within the end cap 9 or associated opening in the housing 2 .

[0036] Each microfiltration or ultrafiltration membrane 3 can be, for example, a spiral wound or particularly a hollow fiber membrane, the latter being particularly preferred. The hollow fiber membranes can each have multiple capillaries to increase the effective surface area. The hollow fiber membranes are typically potted at each end to secure the hollow fiber membrane within the interior volume 20 of the housing 2. Typically, multiple hollow fiber membranes are provided, the total number of which can be, for example, 10 to 10,000 or more. The active membrane area can be, for example, 10 to 250 m 2 The hollow fiber membranes are generally separated from one another to allow fluid (optionally a feed fluid or filtrate) to flow between the hollow fibers. The term "vertically oriented," as used herein with respect to hollow fiber membranes, means that the length of the hollow fiber is arranged parallel to the central axis of the cylindrical housing. Suitable microfiltration and ultrafiltration membranes and membrane configurations for use in housings such as housing 2 are described, for example, in International Patent Application Publication No. WO 2020 / 094463 by Heijnen and Staaks.

[0037] The filtration assembly 100 and filtration system 101 described herein may be operated in a manner similar to conventional filtration elements lacking filter 11. In one mode of operation, a feed fluid is introduced under pressure into opening 8 in inlet end cap 7, through filter 11 and housing inlet 6 in housing 2, and into interior volume 20. Within interior volume 20, a portion of the feed fluid passes through one or more microporous or ultrafiltration membranes 3, thereby separating it into a filtrate (or reject) and a retentate. In the specific embodiment shown in FIGS. 1-3, the filtrate and retentate are separately removed from filtration element 1 via outlets 4 and 5, respectively.

[0038] In another embodiment and corresponding mode of operation, filtration assembly 100 is adapted to receive a feed flow from both ends of filtration element 1, i.e., through housing inlet 6 and through an upper opening at the opposite end of housing 2 (which serves as second housing inlet 6 in such an embodiment). In such an embodiment, the feed fluid is introduced through housing inlet 6 and opposing open deadheads in filtration element 1. A portion of the feed fluid permeates microfiltration or ultrafiltration membrane 3 to produce filtrate, which is removed via a filtrate outlet, such as outlet 4. Rejectants in such an embodiment are typically retained within microfiltration or ultrafiltration membrane 3. The rejects are periodically removed by backwashing or flushing the rejects from microfiltration or ultrafiltration membrane 3, typically via either or both of housing inlet 6 and the upper opening of housing 2. In such an embodiment, a filter, such as filter 11, is preferably associated with the upper opening of housing 2 in the same manner as described for filter 11 associated with housing inlet 6. As previously mentioned, such a filter is disposed within such an opening or within an associated inlet end cap (such as end cap 9 of FIG. 1 ) and within the flow path of the feed fluid from the inlet opening in end cap 9 to the associated opening in housing 2. End cap 9 in such a case is generally as described with respect to inlet end cap 7, and is preferably a T-piece as described with respect to inlet end cap 7.

[0039] Pertinent characteristics of filter 11 when associated with the top opening of housing 2 are as described above with respect to filter 11 associated with housing inlet 6. The materials, arrangement, and configuration of the filters at the top opening and inlet may correspond in some way, such as by mirror symmetry. However, the characteristics of filter 11 at housing inlet 6 and the top opening of filter element 1 are independent of each other and may be the same or different.

[0040] The filtration elements 100 described herein can be operated in either an inside-outside mode of operation or an outside-inside mode of operation.

[0041] In an inside-outside mode of operation, the feed fluid is fed into the capillaries of the hollow fiber membranes 3, and the filtrate passes through the membranes and enters the open spaces between the membranes 3 within the interior volume 20 of the housing 2. For the particular embodiment shown in Figures 1-3, the filtrate in such a case is removed via outlet 4 and the retentate is removed via outlet 5. In an outside-inside mode of operation, the feed fluid is fed into the open spaces in the interior volume 20 between the hollow fiber membranes 3, and the filtrate passes through the membranes and enters the capillaries. In such a case, the retentate is removed via outlet 4 and the filtrate is removed via outlet 5.

[0042] Conduits for the collected filtrate and concentrate are typically provided and are in fluid communication with corresponding outlets in the filtration element 1 for collecting the filtrate and concentrate for use, disposal, and / or further processing (such as by nanofiltration or reverse osmosis). As previously mentioned, some or all of such conduits may be formed by connected T-pieces of adjacent filtration elements, as shown in FIG. 5.

[0043] Due to the presence of filter 11 in filtration assembly 100, it is often unnecessary to treat the incoming feed fluid with an upstream filtration step, such as by passing it through a separate upstream filtration device. Thus, such upstream filtration devices can often be omitted, which represents a significant savings in both capital and operating costs.

[0044] Cleaning is conveniently accomplished by passing one or more backwash fluids through filtration assembly 100 in opposite directions, i.e., into filtration element 1 via either or both outlets 4 and 5, and removed therefrom through housing inlet 6 of housing 2. The backwash fluid passes from housing inlet 6 of housing 2 into inlet end cap 7, through filter 11, and is removed from inlet end cap 7 via an opening therein, such as opening 8 or outlet 18.

[0045] A significant and surprising advantage of the filtration assemblies described herein is that most or all of the scale, trapped solids, and other debris dislodged from the membrane surface during the cleaning process easily passes through the filter 11 and can be easily removed from the filtration element 1 despite the presence of the filter. Loosely agglomerated material tends to break down during the cleaning process, leaving little, if any, retention on the filter. Therefore, it is often unnecessary to remove the filter 11 from the filtration element 1 prior to backwashing, although doing so is within the scope of the processes described herein, particularly in preferred processes in which the filter 11 is removable. It may be beneficial to perform periodic cleaning / backwashing operations with the filter in place within the filtration element 1 and less frequent cleaning / backwashing operations with the filter removed to ensure complete removal of solids that do not pass through the filter. Cleaning and / or backwashing may include a chemical cleaning step.

[0046] In embodiments in which the inlet end cap 7 and the end cap 9 are each T-pieces (as shown in FIGS. 1 and 5 ), the filtration element 100 is suitable for use in a multi-element filtration system, as described in EP 1743690 B1. Such multi-element filtration systems are characterized by having a plurality of filtration elements arranged in a row, with the upper and lower T-piece end caps of each element joined, directly or indirectly, to the T-piece end caps of adjacent filtration elements to form liquid conduits. Similarly, in the arrays provided herein, the T-piece inlet end caps 7 of adjacent filtration assemblies 100 are joined to create a feed fluid supply line that supplies a feed fluid to each filtration element in the row. Similarly, the T-piece outlet end caps 9 of adjacent filtration elements are joined to create a return line for recovering filtrate or concentrate from each filtration element 1 in the row.

[0047] 4 and 5, one embodiment of such a multi-element filtration system 101 is shown, in this case having two rows of filtration assemblies 100 comprising filtration elements 1. The inlet end caps 7 of the filtration elements 1 in each row are joined to create a fluid feed conduit 75. The T-piece outlet end caps 9 of the filtration elements 1 in each row are joined to create a concentrate return conduit 95. The outlets 4 of the filtration elements 1 are in fluid communication with a filtrate drain conduit 60 via connectors 61. As shown, aligned filtration elements 1 from each row each feed a single filtrate drain conduit 60. However, each filtration element in the row may feed a separate drain conduit if desired. The filtrate drain conduit 60, as shown, is preferably located above the concentrate return conduit 95. Such a system is described in more detail in EP 1 743 690 B1.

[0048] In another preferred embodiment, the filtration system 101 described herein comprises: A plurality of optionally cylindrical filtering elements 1 arranged in parallel, each of said filtering elements 1 comprising: a housing 2 enclosing an internal volume 20; a plurality of membranes 3 disposed within the interior volume 20, said membranes 3 being selected from the group consisting of microfiltration, ultrafiltration, nanofiltration, and reverse osmosis membranes, said membranes 3 dividing the interior volume 20 into a feed region and a filtrate region; a housing inlet 6 for introducing a feed fluid into a feed region of the filtration element 1; a plurality of optionally cylindrical filtration elements 1, including a housing outlet 4 for removing filtrate from a filtrate region of the filtration elements 1; a manifold having a distribution conduit and a plurality of manifold outlets, or alternatively, a supply fluid conduit (75) and a plurality of fluid connections between the supply fluid conduit (75) and the filter element (11); Each of the plurality of filtration elements 1 is associated with a particular manifold outlet or fluid connection such that the plurality of membranes 3 within the filtration element 1 receive supply fluid from the particular manifold outlet or fluid connection, and at least one filter 11 is disposed along the supply flow path between the membranes 3 within the housing 2 of the filtration element 1 and the associated manifold outlet.

[0049] 4 and 5, a filtration assembly 100 preferably includes a distributor 75 and a plurality of filtration elements 1. In a more preferred embodiment, each filtration element 1 is associated with a particular distributor outlet region 77 such that the membrane 3 within that filtration element 1 receives feed fluid from that particular distributor outlet region 77.

[0050] The distributor 75 includes a feed fluid conduit 76 and multiple distributor outlet regions 77. The distributor 75 itself can be a single unit or an assembly. As shown in FIG. 5 , the feed fluid conduit 76 is preferably a collinear region suitable for conveying a common feed to multiple different filtration elements 1. Preferably, the multiple different filtration elements 1 are arranged in parallel within the filtration assembly 100. The common feed within the feed fluid conduit 75 preferably comes from a common source (e.g., a pump or pre-filter serving two or more filtration elements 1). The feed fluid conduit 76 is in fluid communication with multiple distributor outlet regions 77. Each distributor outlet region 77 is a separate region from the feed fluid conduit 76, and the distributor outlet regions 77 are defined by an event horizon or fluid flow transition, such that the feed fluid passing through a distributor outlet region 77 is associated with a single filtration element 1.

[0051] At least one filter 11 is disposed along the feed flow path between the membrane 3 within the housing 2 of the filtration element 1 and an associated distributor outlet region 77. In Figures 4 and 5, the distributor 75 is shown as an assembly of connected inlet end caps 7 that together form a continuous, straight feed fluid conduit 76. In this embodiment, each inlet end cap 7 includes a distributor outlet region 77 immediately upstream of the filter 11. In other embodiments, the filter 11 may be located further downstream, including outside the inlet end caps 7.

[0052] Each filtration element 1 in the filtration assembly 100 is preferably associated with a particular distributor outlet region 77 and at least one associated filter 11. The filter apertures preferably have a nominal size in the range of 5 to 500 μm. The filters 11 are positioned along the feed flow path between the membrane 3 in the housing 2 of that filtration element 1 and the associated distributor outlet region. Feed fluid passing through the associated filter 11 is destined for (and associated with) the particular associated element 1. Thus, each associated filter 11 is at or downstream of the event horizon defining the distributor outlet region 77.

[0053] 4 and 5, one skilled in the art would readily understand how the multiple membranes 3 disposed within the interior volume 20 divide the interior volume 20 into a feed region and a filtrate region. For example, the lumen of a hollow fiber and the exterior of the same hollow fiber would each correspond to two distinct regions within the interior volume; these two regions are the feed region and the filtrate region.

[0054] Furthermore, in this apparatus, each filtration element 1 is preferably associated with at least one filter 11 located along the feed flow path between a membrane 3 within the housing 2 of that filtration element 1 and an associated manifold outlet. Preferably, the nominal aperture size of the filter 11 is in the range of 5 to 500 μm. The membranes 3 are independently selected; that is, the filtration element 1 may include a plurality of one type of membrane 3, or any combination of two or more types of membranes 3.

[0055] The multi-element filtration devices described herein are useful for filtering a wide variety of fluids, particularly aqueous fluids, such as groundwater, surface water, seawater, process streams from chemical operations and / or power generation stations, and many others. In certain embodiments, the multi-element filtration device is a seawater ultrafiltration and / or microfiltration device, and can be used, for example, as a prefilter to prepare seawater for reverse osmosis to produce drinking water.

[0056] The following examples are provided to further illustrate the present invention, which illustrate specific embodiments and preferred modes presently contemplated for carrying out the invention, and are intended to illustrate, but not limit, the present invention. [Example]

[0057] A filtration element such as that shown in Figures 1-3 is installed in a pilot-scale filtration system. Unfiltered feedwater is supplied to filtration element 1 through opening 8 in T-piece 7, from which it flows through body 23 of T-piece 7 and filter 11 before entering housing 2 via housing inlet 6. The filtration element includes hollow fiber membranes 3 operated in an inside-outside mode to produce filtrate, which is removed via outlet 4, and permeate, which enters T-piece 9 and is also removed.

[0058] Pressure is measured directly above and below the filter 11 to determine the pressure drop across the filter. During 80 days of continuous operation, the pressure drop remains consistently at 0.02 bar (2 KPa) with no pressure deviations exceeding 0.1 bar (10 KPa). The filtered water quality is not substantially different from the baseline case where a similar filtration element without filter 11 is supplied with unfiltered feedwater.

[0059] During operation, solids passing through the filter 11 accumulate and form agglomerates within the filtration element 1, particularly within the hollow fiber membrane 3. Backwashing breaks up the agglomerates, allowing them to easily pass back through the filter 11. Periodic chemical cleaning cleans both the membrane 3 and the filter 11.

[0060] While certain preferred embodiments of the present invention have been described and specifically exemplified above, it is not intended that the present invention be limited to such embodiments. Rather, while many of the features and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, it is to be understood that the present disclosure is merely illustrative, and that changes may be made in details, particularly with respect to the shape, size, and arrangement of parts, within the principles of the invention to the fullest extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims

1. 1. A filtration assembly 100 comprising: a) a housing 2 enclosing an interior volume 20 of the filtration assembly 100; b) at least one microfiltration or ultrafiltration membrane 3 disposed within the internal volume 20 of the housing 2; c) at least one outlet 4 for removing filtrate from said housing 2; d) at least one housing inlet 6 in said housing 2 for introducing a feed fluid into said housing 2; e) for at least one housing inlet 6, an associated inlet end cap 7 attached to the housing 2 and in fluid communication with the housing inlet 6 of the housing 2, the inlet end cap 7 having an opening 8 for receiving a supply fluid and defining a flow path for the supply fluid from the opening 8 in the inlet end cap 7 to the associated housing inlet 6 of the housing 2; f) a filtration assembly 100 including, for at least one housing inlet 6 having an associated inlet end cap 7, an associated filter 11 disposed (i) within the housing inlet 6 or (ii) within the associated inlet end cap 7 and within the flow path of the supply fluid from the opening 8 of the inlet cap 7 to the associated housing inlet 6 in the housing 2.

2. 1. A filtration assembly 100 comprising: a) a housing 2 enclosing an internal volume 20; b) at least one microfiltration or ultrafiltration membrane 3 disposed within the internal volume 20 of the housing 2; c) at least one outlet 4 for removing filtrate from said filtering element 1; d) at least one housing inlet 6 in said housing 2 for introducing a feed fluid into said filtering element 1; e) for at least one housing inlet 6, an associated inlet end cap 7 attached to the housing 2 and in fluid communication with the housing inlet 6 in the housing 2, the inlet end cap 7 having an opening 8 for receiving a supply fluid and defining a flow path for the supply fluid from the opening 8 in the inlet end cap 7 to the associated housing inlet 6 in the housing 2; f) a filtration assembly 100 including, for at least one housing inlet 6, an associated filter 11 positioned (i) within the housing inlet 6 or (ii) within the flow path of the supply fluid to the associated housing inlet 6 in the housing 2.

3. 3. The filtration assembly (100) of claim 1 or 2, wherein the filters (11) are oriented transversely to the direction of flow of feed fluid through the associated housing inlet (6).

4. The filtration assembly (100) of any one of claims 1 to 3, wherein the filter (11) is a screen or the apertures of the filter have a nominal size in the range of 5 to 500 μm.

5. The filter assembly (100) of any one of claims 1 to 4, wherein the filter (11) is removably attached.

6. The filter assembly (100) of any one of claims 1 to 5, further comprising a filter mount (12) at the housing inlet (6) or the inlet end cap (7) of the housing (2), the filter (11) being attached to the filter mount (12).

7. The filter assembly (100) of claim 6, wherein the filter mount (12) is a mounting ring.

8. The filtration assembly (100) of any one of claims 1 to 7, wherein the filter (11) has a surface area that is at least 40% of the surface area of ​​the associated housing inlet (6) of the housing (2).

9. The filtration assembly (100) of any one of claims 1 to 8, wherein the filter (11) comprises a plurality of smaller filter elements assembled to form the filter (11).

10. 10. The filtration assembly 100 of any one of claims 1 to 9, wherein each inlet end cap 7 is a T-piece adapted to engage with a T-piece inlet end cap of an adjacent filtration element on each opposite side to create an inlet conduit 75.

11. 11. The filtration assembly (100) of any one of claims 1 to 10, further comprising an outlet end cap (9) attached to the housing (2) and in fluid communication with the interior volume (20) of the housing (2) and defining a flow path for concentrate and / or filtrate from the interior volume (20) of the filtration element to the outlet (5) of the outlet end cap (9).

12. 12. The filtration assembly 100 of claim 11, wherein the outlet end cap 9 is a T-piece adapted to engage with a T-piece outlet end cap of an adjacent filtration element on each opposite side to create an outlet conduit 60.

13. A filtration assembly (100) according to any preceding claim, wherein a housing inlet (6) and associated inlet end cap (7) in the housing (2) is at the lower end of the housing (2).

14. A filtration assembly (100) according to any one of claims 1 to 13, wherein a housing inlet (6) and associated end cap (7) are at the upper end of the housing (2).

15. A filtration assembly (100) according to any one of claims 1 to 14, wherein a first housing inlet (6), a first end cap (7), and a first filter (11) associated with the first housing inlet (6) are located at an upper end of the housing (2), and a second housing inlet (6), a second end cap (7), and a second filter (11) associated with the second housing inlet (6) are located at a lower end of the housing (2).

16. The filtration assembly (100) of any one of claims 1 to 15, further comprising a concentrate outlet port (5) in the housing (2) for removing concentrate from the internal volume (20) of the filtration element (1).

17. Filtration assembly (100) according to any one of claims 1 to 16, wherein the microfiltration or ultrafiltration membrane (3) comprises a plurality of vertically oriented hollow fibres.

18. A filtration system (101) comprising two or more filtration assemblies (100) according to any one of claims 1 to 17, optionally arranged vertically in a row.

19. 20. The filtration system (101) of claim 18, wherein the inlet end caps (7) of the plurality of filtration elements in a row are connected with a T-piece to create a supply fluid conduit (75).

20. 20. The filtration system 101 of claim 18 or 19, wherein the plurality of filtration elements 100 arranged in a row each further includes an outlet end cap 9 attached to the housing 2, fluidly connected to the internal volume 20 of the housing 2, and defining a flow path for concentrate and / or filtrate from the internal volume 20 of the filtration element to an outlet of the outlet end cap 9, the outlet end caps 9 being T-pieces adapted to engage with T-piece outlet end caps of adjacent filtration elements on each opposite side to create an outflow conduit 60, and the T-piece outlet end caps are connected together to create a concentrate recovery pipe 95.

21. Filtration system 101 as described in claim 18, 19, or 20, wherein each of the filtration elements 100 further includes a filtrate outlet port 4 in the housing 2 for removing filtrate from the internal volume 20 of the filtration element 100, and each filtrate outlet port 4 is in fluid communication with a filtrate collection conduit 60 extending above and parallel to the concentrate collection pipe 95.

22. A filtration assembly 100 for filtering a feed fluid, said filtration assembly 100 comprising a plurality of parallel-arranged filtration elements 1, each of said filtration elements 1 having: a housing 2 enclosing an internal volume 20; a plurality of membranes 3 located within the interior volume 20, the membranes 3 dividing the interior volume 20 into a feed region and a filtrate region; a housing inlet 6 for introducing a feed fluid into said feed region; a housing outlet 4 for removing filtrate from said filtrate region; a distributor 75 having a supply fluid conduit 76 and a plurality of distributor outlet areas 77; A filtration assembly 100, wherein each of the plurality of filtration elements 1 is associated with a particular distributor outlet area 77 such that the plurality of membranes 3 within the filtration element 1 receive feed fluid from the particular distributor outlet area 77, and at least one filter 11 is located along the feed flow path between the membrane 3 within the housing 2 of the filtration element 1 and the associated distributor outlet area 77.

23. 23. The filtration assembly of claim 22, wherein the apertures of the filter have a nominal size in the range of 5 to 500 μm or the membrane is a hollow fiber membrane.

24. 24. A filtration system comprising two or more of the filtration assemblies 100 of claim 22 or 23.

25. 17. A filtration process comprising: introducing a feed fluid into a filtration system (101) comprising a filtration element (100) according to any one of claims 1 to 16 through an inlet end cap associated filter (11) and an associated housing inlet (6); passing at least a portion of the feed fluid through the microfiltration and / or ultrafiltration membrane (3) to produce a filtrate and a concentrate; and removing the filtrate and the concentrate from the filtration element (1).

26. 20. A filtration process comprising introducing a feed fluid into a filtration system 101 according to any one of claims 18-21 or 24 through an inlet end cap associated filter 11 and an associated housing inlet 6, passing at least a portion of the feed fluid through the microfiltration and / or ultrafiltration membrane 3 to produce a filtrate and a concentrate, and removing the filtrate and the concentrate from the filtration element 1.

27. 27. The filtration process of claim 25 or 26, further comprising a backwash step in which a backwash liquid is introduced into the filtration element 1, at least a portion of the backwash liquid is directed to contact the microfiltration and / or ultrafiltration membrane 3, and then exits the filtration element through a housing outlet 6, an associated filter 11, and an associated inlet end cap 7.

28. 28. The filtration process of claim 27, wherein the backwashing step comprises a chemical cleaning step.

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