Permeable carrier with circular double-sided knitted fabric

Abstract

The present application relates to a permeable carrier having a circular double-sided knitted fabric. A system includes a first filtration membrane layer, a second filtration membrane layer, a permeable carrier disposed between the first membrane layer and the second membrane layer, and a core. The permeable carrier includes a knitted fabric sheet including a first yarn and a second yarn knitted together in a circular knitting pattern. The circular knitting pattern includes a channel between the first yarn and the second yarn, and the permeable carrier supports the first filtration membrane layer and the second filtration membrane layer. The first filtration membrane layer, the second filtration membrane layer, and the permeable carrier are wrapped around the core.

Description

Technical Field

[0001] In at least one aspect, the present invention relates to filter elements for reverse osmosis, nanofiltration, ultrafiltration or microfiltration systems; and more particularly to filter elements comprising a permeate carrier. Brief description of the attached diagram

[0002] Figure 1 This is a schematic diagram of a water purification system according to one implementation scheme.

[0003] Figure 2A This is a perspective view of a filter structure with a tear to expose a filter element layer according to one embodiment.

[0004] Figure 2B This is a side view showing more than one filter element according to one embodiment.

[0005] Figure 3 This is a schematic diagram of the surface of a circular double-sided knitted fabric sheet according to one embodiment.

[0006] Figure 4 It is the cross-section of a bicomponent yarn fiber.

[0007] Figure 5 This is a graph showing the flow-to-pressure performance of a permeating carrier according to one embodiment compared to a conventional permeating carrier. Detailed description

[0008] Reference will now be made in detail to the embodiments, examples of which are shown in the accompanying drawings. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the various embodiments described. However, it will be apparent to those skilled in the art that the various embodiments described can be practiced without these specific details. In other instances, well-known methods, procedures, components, circuits, and networks have not been described in detail to avoid unnecessarily obscuring aspects of the embodiments.

[0009] It should be understood that the disclosed embodiments are merely exemplary, and various and alternative forms are possible. The drawings are not necessarily to scale; some features may be exaggerated or minimized to show details of specific components. Therefore, the specific structural and functional details disclosed herein should not be interpreted as limiting, but merely as a representative basis for teaching those skilled in the art to adopt embodiments according to this disclosure in various ways.

[0010] "One or more" includes functions performed by one element, functions performed by more than one element (e.g., in a distributed manner), several functions performed by one element, several functions performed by several elements, or any combination of the foregoing.

[0011] It should also be understood that although the terms first, second, etc., are used in some instances herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, a first contact may be referred to as a second contact, and similarly, a second contact may be referred to as a first contact, without departing from the scope of the various embodiments described. Both the first contact and the second contact are contacts, but they are not the same contact.

[0012] The terminology used in the description of the various embodiments described herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments described and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that, as used herein, the term “and / or” refers to and covers any and all possible combinations of one or more of the related items listed. It should be further understood that, when used in this specification, the terms “includes,” “including,” “comprises,” and / or “comprising” indicate the presence of the recited features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0013] As used herein, depending on the context, the term "if" is optionally interpreted as meaning "when," "at," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if [the condition or event] is detected" is optionally interpreted as meaning "when determination," "in response to determination," "when [the condition or event] is detected," or "in response to detection."

[0014] Except where explicitly stated in any example or otherwise, all numerical quantities indicating the amount of material or reaction conditions and / or conditions of use in this specification should be understood to be modified by the word “about” when describing the broadest scope of the invention. Practice within the stated numerical limits is generally preferred. As used herein, the term “about” means that the quantity or value in question may be a specific value or some other value in its neighborhood. The term “about” or “approximately” indicating a value is intended to indicate a range within + / - 5% of that value. As an example, the phrase “about 10” indicates a range of 10 + / - 5, that is, a range from 95 to 105. When the terms “about” or “approximately” are used, similar results or effects according to the invention can be expected to be obtained within a range of + / - 5% of the indicated value. It should also be understood that integer ranges (e.g., for measurements or dimensions) explicitly include all integers in between. For example, the integer range 1-10 explicitly includes 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Similarly, the range 1 to 100 includes 1, 2, 3, 4, ... 97, 98, 99, 100. Likewise, when any range is required, the middle number obtained by dividing the difference between the upper and lower limits by 10 as the increment can be considered as an optional upper or lower limit. For example, if the range is 1.1 to 2.1, the following numbers 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0 can be chosen as either the lower or upper limit.

[0015] Furthermore, unless explicitly stated to the contrary: percentages, "parts of," and proportions are by weight; the term "polymer" includes "oligomer," "copolymer," "terpolymer," and the like; the molecular weight provided for any polymer is a weight-average molecular weight unless otherwise specified; a description of a group or class of materials suitable or preferred for a given purpose relating to the invention means that a mixture of any two or more members of that group or class is equally suitable or preferred; descriptions of components in chemical terms refer to components when added to any combination specified in the description and do not necessarily exclude chemical interactions between components of the mixture after mixing; the first definition of acronyms or other abbreviations applies to all subsequent uses of the same abbreviations herein, and common grammatical variations of the abbreviations with necessary modifications apply to the initial definitions; and unless explicitly stated to the contrary, performance is determined by the same technique as that mentioned above or below for the same performance.

[0016] It should also be understood that the present invention is not limited to the specific embodiments and methods described below, as specific components and / or conditions can certainly vary. Furthermore, the terminology used herein is for the purpose of describing specific embodiments of the invention only and is not intended to be limiting in any way.

[0017] Water is in constant demand in both industrial and public environments. Therefore, there is a need for processes that facilitate the recycling and purification of contaminated or impure water for drinking reuse. Some non-limiting examples of conventional water purification processes include biological activated sludge processes, biological nutrient removal processes, chemical processes such as softening, disinfection, and oxidation, and membrane processes including reverse osmosis, nanofiltration, ultrafiltration, and microfiltration. Operating conditions can vary depending on the type of process. Typically, some water purification methods via membrane processes operate at high pressures, necessitating that system components be designed to withstand the pressure for efficient operation. These components have limited efficiency in low-pressure environments.

[0018] refer to Figure 1 A schematic diagram of a water purification system is provided. The water purification system 10 includes one or more filters 12. The water purification system 10 (and filters 12) can be used in reverse osmosis, nanofiltration, ultrafiltration, or microfiltration systems. The water purification system 10 includes a supply water source 14 fluidly connected to a control valve 16 via conduit 18, the control valve 16 regulating or controlling (e.g., opening / closing) the flow rate of the supply water into the conduit 18. The supply water flows through the conduit 18 to one or more filter units 20, 22 before passing through the filters 12, each filter 12 being enclosed in a corresponding housing 24. The filter units 20, 22 are any suitable filter units or combinations of units other than membrane-based filters, such as, but not limited to, sediment filtration units including sand filters, carbon filtration units including activated carbon filters, softener filtration units including ion exchange filters, or kinetic degradation flux filtration units. Although two filter units 20, 22 are shown, any suitable number of filter units can be utilized based on various factors such as, for example, system scaling. Similarly, although four filters 12 are shown, any suitable number of filters 12 can be utilized based on various factors such as, for example, system scaling. In some embodiments and as... Figure 1As shown, after water passes through filter 12, the filtered water is directed to distributor 31 via pipe 19. Distributor 31 directs the filtered water to a first stream via pipe 29 to pass through additional filter units 26, 28 to produce purified water for storage in tank 30. Although two filter units 26, 28 are shown, any suitable number of filter units can be used based on various factors such as, for example, system scaling. Filter units 26, 28 are any suitable filter units or combinations of units other than membrane-based filters, such as, but not limited to, sediment filtration units including sand filters, carbon filtration units including activated carbon filters, softener filtration units including ion exchange filters, or kinetic degradation flux filtration units. Distributor 31 directs the filtered water to a second stream via pipe 33 to pass through one or more filter units 32 to form purified water, which can be introduced via valve 34 or otherwise directed. Although one filter unit 32 is shown, any suitable number of filter units can be used based on various factors such as, for example, system scaling. Similar to filter units 20, 22, 26, and 28, filter unit 32 is any suitable filter unit as described above. Although the diverter 31 is shown as forming two routes 29 and 33 from pipe 19, any suitable number of routes can be branched off from the diverter 31, and the description of the two routes is not intended to be limiting. For example, additional routes may include additional filter units to deliver purified water to additional storage tanks or other valves and the like.

[0019] refer to Figure 2A and Figure 2B It provides filter structures for reverse osmosis, nanofiltration, ultrafiltration, or microfiltration systems. Figure 2A This is a perspective view of one of the filters 12 enclosed in housing 24, wherein housing 24 has a tear to expose filter element 40. Figure 2BThis is a side view showing more than one filter element 40, 40'. Although six filter elements 40, 40' are shown, any suitable number of filter elements can be used based on various factors such as, for example, system scaling. Filter 12 includes filter element 40, which includes a composite comprising a feed spacer 42, a permeate carrier 44, and a water filtration membrane 46. Therefore, filter element 40 can be interchangeably referred to as filter element composite 40 or simply composite 40. Permeate carrier 44 is composed of a circular double-knitted fabric sheet 47. Filter 12 may include any number or more of composites 40. The number of composites 40 can vary based on system pressure. Typically, for applications with lower pressures, the amount of permeate carrier or composite can be less. In one embodiment, filter 12 may include ten composites 40 and can operate at a system pressure of 1000 psi. In another embodiment, filter 12 may include three composites 40 and can operate at a system pressure of 400 psi.

[0020] Refer again Figure 2A and Figure 2B The permeate carrier 44 is positioned between two water filter membranes 46, and the feed spacer 42 is positioned on the outside of one of the water filter membranes 46. In a variant, although not shown, the permeate carrier 44 may be positioned between the feed spacer 42 and the water filter membrane 46. When operating under system pressure, the permeate carrier 44 structurally supports the water filter membrane 46 to prevent collapse of the membrane 46. The permeate carrier 44, comprising a circular double-knitted fabric sheet 47, is a porous sheet that guides and directs water flow through it and maintains a low pressure drop while withstanding applied pressure without experiencing compaction. Channels 50 defined in the permeate carrier 44 define flow channels along the technical front and technical back sides of the knitted fabric for the flow of water filtered by the adjacent water filter membranes.

[0021] In at least one implementation, refer again Figure 2B Filter 12 includes additional filter elements 40' stacked on top of filter element 40. For example... Figure 2B The additional filter elements 40' shown similarly include a permeate carrier 44 positioned between the two water filter membranes; however, other arrangements (e.g., the permeate carrier 44 located between the water filter membranes and the feed spacer) and combinations thereof are also contemplated. These additional filter elements 40' overlap each other and overlap with filter element 40. The entire filter element stack, including filter elements 40, 40', is wound around the perforated core 58, as shown. Figure 2AThe end view V1 and cross-sectional view V2 are shown in the figure, forming a wound stack 64. In at least one embodiment, the perforated core 58 is a perforated tube formed of a suitable material having sufficient mechanical strength and corrosion resistance, including but not limited to steel, stainless steel, polyvinyl chloride (PVC), acrylonitrile-butadiene-styrene (ABS), polypropylene (PP), polyphenylene ether (PPE), polyphenylene oxide (PPO), polysulfone (PSU), or the like. The wound stack 64 of filter elements 40, 40' attached to the perforated core 58 is positioned in the housing 24 and held in place by end caps 66, 68.

[0022] Refer again Figure 2A The filter 12 includes a perforated core 58 in direct contact with the feed spacer 42; however, in other embodiments, although not shown, the perforated core 58 may be in direct contact with the permeate carrier 44. The perforated core 58 receives filtered water that has passed through the water filter membrane 46 and the winding stack 64 into the interior of the perforated core 58. Arrow 72 indicates that the supply water is introduced into the winding stack 64 of the filter 12 generally in an axial direction defined along the length of the winding stack 64. The supply water flows axially through the feed spacer 42 as indicated by arrow 74. A portion of the supply water is filtered by flowing through the layers of the winding stack 64 and the water filter membrane 46, and as indicated by arrow 76, by moving radially inward through the layers of the winding stack 64 to reach the perforated core 58, thus forming filtered water. The filtered water exits the perforated core 58 as indicated by arrow 78. Concentrated water containing impurities exits the winding stack 64 of the filter 12 as a separate concentrated stream, indicated by arrow 80. In this respect, the filtered water is water with fewer impurities than the supply water.

[0023] Figure 3This is an illustration of one side of a circular double-knitted fabric sheet 47 according to one embodiment. The circular double-knitted fabric sheet 47 comprises synthetic yarns knitted into rows 150, 150' and warp rows 160, 162, 164. Rows 150, 150' comprise horizontal rows of yarn loops. Row 150 comprises horizontal rows of yarn loops on a first side of the fabric sheet 47, and row 150' comprises horizontal rows of yarn loops on a second side of the fabric sheet 47. Warp rows 160, 162, 164 comprise vertical rows of stitches 170, 170', 172, 172', 174, 174'. Stitches 170, 172, 174 are formed on the first side of the fabric sheet 47 by interlocking yarns from the previous row with yarns from row 150. By interlocking the yarn from the previous row with the yarn from row 150', stitches 170', 172', and 174' are formed on the second surface of fabric piece 47. When knitting fabric piece 47, the yarn alternates from the first surface to the second surface, such that the yarn alternately forms stitches, for example, stitch 170' on the first surface and stitches, for example, stitch 172', on the second surface. Warp rows 160, 162, and 164 define channels 50 within the circular double-sided knitted fabric piece 47.

[0024] As described above, the permeation carrier 44 comprises a circular double-knitted fabric sheet comprising synthetic yarns. In one aspect, the circular double-knitted fabric sheet comprises a first yarn and a second yarn. In some embodiments, the first yarn and the second yarn have different dimensions and / or different materials. In one embodiment, the first yarn and the second yarn comprise the same material, but the denier of the first yarn is different from that of the second yarn. The first yarn and the second yarn are knitted together in a circular double-knitted pattern. The circular double-knitted pattern is formed using a weft knitting technique, wherein a fabric sheet is formed comprising two sides knitted together, for example, interlocking. Thus, the circular double-knitted fabric sheet comprises a relatively smooth front and back side, as opposed to a single-knitted fabric sheet, for example, having a smooth front side and a back side comprising a series of raised ridges or ribs. The permeation carrier 44 is configured to be placed between adjacent water filtration membranes in a water filtration system.

[0025] Circular double-knitted fabric sheets are typically formed using circular knitting machines. Circular knitting machines form fabric sheets with a tubular shape by knitting in a continuous direction rather than alternating between two directions. Therefore, circular knitting machines produce fabric sheets with lower time and energy input. In filtration systems operating at lower pressures (e.g., 60 psi to 500 psi in some embodiments, and 200 psi to 500 psi in others), where structural features may be unnecessary, the performance of filters with permeation carriers featuring circular double-knitted fabrics is achieved at a reduced input cost.

[0026] The permeate carrier 44 is further characterized by the thickness of the circular double-knitted fabric sheet. According to one embodiment, the permeate carrier 44 comprises a thickness of approximately 5 mm to 15 mm. In one improvement, the thickness of the circular double-knitted fabric sheet is 9 mm to 11 mm. In another improvement, the thickness of the circular double-knitted fabric sheet is 10.5 mm. A greater thickness of the permeate carrier 44 alters the geometry of the flow channels through which the permeate (e.g., water) flows. A thinner permeate carrier 44 increases the flow resistance through the fabric sheet, thus requiring a higher energy input to maintain a constant volumetric water flow rate. The thickness of the permeate carrier 44 may also affect the packing density of the filter element composite and therefore the overall capacity of the purification system.

[0027] In some embodiments, the thickness of the circular double-knitted fabric sheet is influenced by the size and weight of the first and second yarns. In various embodiments, the yarn denier (i.e., the fiber mass in grams per 9,000 meters) also affects the flow efficiency and structural support provided by the permeation carrier 44. The first and second yarns comprise about 40 to 100 deniers in one embodiment, 40 to 80 deniers in another, and 40 to 60 deniers in yet another embodiment. In one aspect, the first yarn comprises about 40 to 60 deniers, and the second yarn comprises about 60 to 80 deniers. In yet another aspect, the first yarn comprises about 50 deniers, and the second yarn comprises about 70 deniers. In at least one embodiment, the second yarn has a denier greater than that of the first yarn.

[0028] It should also be understood that the present invention is not limited to the type of yarn used for circular double-knitted fabric sheets. The synthetic yarn can be a monofilament yarn or a yarn comprising more than one filament. In one improvement, the synthetic yarn comprises a component containing polyester yarn, polypropylene yarn, nylon yarn, or a combination thereof. Reference Figure 4 In at least one embodiment, the multifilament yarn comprises a bicomponent yarn including an outer sheath region 92 and an inner core region 90. This type of yarn is referred to as a core-sheath yarn. In one aspect, the outer sheath region 92 has a lower melting point than the inner core 90. After knitting a circular double-knitted fabric sheet, the fabric sheet is heated above the melting point of the outer sheath region 92, causing adjacent yarns to fuse together. In a variation, the surface of the circular double-knitted fabric sheet may be covered with a component layer having a melting point lower than that of the yarn. The component layer is any suitable thermoplastic polymer or thermosetting resin, and in some embodiments, it may be an epoxy resin layer.

[0029] Figure 5A graph showing the flow rate versus pressure performance of a permeation carrier according to an embodiment of the present invention and two prior art permeation carriers is provided. An example of a permeation carrier according to one embodiment shows similar flow rate maintenance in a pressure range of 60 psi to 250 psi compared to the closest tested prior art sample, and shows an increase in flow rate in a pressure range of 250 psi to 500 psi. According to one aspect of the invention, a pressure between 60 psi and 500 psi provides a water flow rate of approximately 100 ml / min to 250 ml / min. The flow characteristics of a 3-inch × 3-inch section of a finished permeation carrier according to one embodiment were tested relative to two similar prior art fabrics. The fabric was placed inside a pressure chamber, along with a support structure for the fabric, which consisted of a tape layer and a sample filter membrane to simulate the behavior in a section with real filtration conditions. Water was introduced into the system at a constant pressure and funneled through the channels of the fabric being tested. A higher flow rate implies better fabric performance of the finished filter unit. Pressure was applied to the top of the fabric sample, simulating a pressurized water filtration system. Figure 5 As shown on the x-axis, the pressure was increased to 500 psi and the output flow was measured for pressures greater than one.

[0030] aspect Aspect 1. A system comprising: a first filter membrane layer, a second filter membrane layer, and a permeation carrier disposed between the first membrane layer and the second membrane layer, the permeation carrier comprising a knitted fabric sheet comprising a first yarn and a second yarn knitted together in a circular knitted pattern, the circular knitted pattern including channels between the first yarn and the second yarn, the permeation carrier supporting the first filter membrane layer and the second filter membrane layer; and a core, wherein the first filter membrane layer, the second filter membrane layer, and the permeation carrier are wound around the core.

[0031] Aspect 2. The system according to aspect 1, wherein the circular knitted pattern comprises the first yarn and the second yarn forming a first row in horizontal loops, wherein each stitch of the first row interlocks with the second row.

[0032] Aspect 3. The system according to any one of Aspects 1 to 2, wherein the first yarn and the second yarn comprise core-sheath cross-section yarns.

[0033] Aspect 4. The system according to any one of Aspects 1 to 3, wherein the first yarn and the second yarn comprise about 40 denier to 100 denier.

[0034] Aspect 5. The system according to any one of Aspects 1 to 4, wherein the first yarn comprises about 40 denier to 60 denier, and the second yarn comprises about 60 denier to 80 denier.

[0035] Aspect 6. The system according to any one of Aspects 1 to 5, wherein the first yarn comprises about 50 denier and the second yarn comprises about 70 denier.

[0036] Aspect 7. The system according to any one of Aspects 1 to 6, wherein the knitted fabric sheet comprises a thickness of about 5 mm to 15 mm.

[0037] Aspect 8. The system according to any one of Aspects 1 to 7, wherein the knitted fabric sheet comprises a thickness of about 9 mm to 11 mm.

[0038] Aspect 9. The system according to any one of Aspects 1 to 8, wherein the knitted fabric sheet comprises a thickness of about 10.5 mm.

[0039] Aspect 10. The system according to any one of Aspects 1 to 9, wherein the first yarn and the second yarn alternate between a first side and a second side of the knitted fabric sheet to form a row at the first side and the second side, wherein the row interlocks with the preceding row to form a stitch at the first side and the second side.

[0040] Aspect 11. A system comprising: a first filter membrane; a second filter membrane; and a permeation carrier disposed between the first filter membrane and the second filter membrane, the permeation carrier comprising a knitted fabric comprising first yarns and second yarns knitted together in a circular knitted pattern.

[0041] Aspect 12. The system according to aspect 11, wherein the water flow rate through the system is approximately 100 ml / min to 250 ml / min at a water pressure between 60 psi and 500 psi.

[0042] Aspect 13. The system according to any one of Aspects 11 to 12, wherein the knitted fabric comprises a thickness of about 5 mm to 15 mm.

[0043] Aspect 14. The system according to any one of Aspects 11 to 13, wherein the knitted fabric comprises a thickness of about 9 mm to 11 mm.

[0044] Aspect 15. The system according to any one of Aspects 11 to 14, wherein the knitted fabric comprises a thickness of about 10.5 mm.

[0045] Aspect 16. A filter comprising: a composite comprising: a first filter membrane layer, a second filter membrane layer, and a permeate carrier disposed between the first membrane layer and the second membrane layer, the permeate carrier comprising a knitted fabric sheet comprising first yarns and second yarns knitted together in a circular knitting pattern, and wherein the permeate carrier supports the first filter membrane layer and the second filter membrane layer; a feed spacer disposed adjacent to the composite; and a perforated core, wherein the composite and the feed spacer are wound around the core, and the permeate carrier is a porous layer.

[0046] Aspect 17. The filter according to aspect 16 further includes a second composite comprising a third membrane layer, a fourth membrane layer, and a second permeation carrier disposed between the third membrane layer and the fourth membrane layer, the second permeation carrier comprising a second knitted fabric sheet, and wherein the second permeation carrier supports the third filter membrane layer and the fourth filter membrane layer.

[0047] Aspect 18. The filter according to any one of Aspects 16 to 17, wherein the perforated core comprises a perforated tube comprising steel, stainless steel, polyvinyl chloride, acrylonitrile-butadiene-styrene, polypropylene, polyphenylene ether, polyphenylene oxide, or polysulfone.

[0048] Aspect 19. The filter according to any one of Aspects 16 to 18, wherein the water flow rate through the filter is about 100 ml / min to 250 ml / min at a water pressure between 60 psi and 500 psi.

[0049] Aspect 20. The filter according to any one of Aspects 16 to 19, wherein the first yarn and the second yarn comprise about 40 denier to 100 denier.

[0050] While exemplary embodiments have been described above, this does not mean that these embodiments describe all possible forms according to this disclosure. In this regard, the language used in the specification is descriptive rather than limiting, and it should be understood that various changes can be made without departing from the spirit and scope of this disclosure. Furthermore, features of various embodiments can be combined to form other embodiments according to this disclosure.

Claims

1. A system comprising: First filter membrane layer, The second filter membrane layer, and A permeation carrier disposed between a first membrane layer and a second membrane layer, the permeation carrier comprising a knitted fabric sheet, the knitted fabric sheet comprising a first yarn and a second yarn knitted together in a circular knitted pattern, the circular knitted pattern comprising a channel between the first yarn and the second yarn, the permeation carrier supporting the first filter membrane layer and the second filter membrane layer; and core, The first filter membrane layer, the second filter membrane layer, and the permeation carrier are wound around the core.

2. The system according to claim 1, wherein, The circular knitted pattern includes the first yarn and the second yarn forming a first row by horizontal loops, wherein each stitch of the first row interlocks with the second row.

3. The system according to claim 1, wherein, The first yarn and the second yarn comprise core-sheath cross-section yarns.

4. The system according to claim 1, wherein, The first yarn and the second yarn comprise approximately 40 denier to 100 denier.

5. The system according to claim 4, wherein, The first yarn comprises about 40 denier to 60 denier, and the second yarn comprises about 60 denier to 80 denier.

6. The system according to claim 5, wherein, The first yarn comprises about 50 denier, and the second yarn comprises about 70 denier.

7. The system according to claim 1, wherein, The knitted fabric sheet has a thickness of approximately 5 mm to 15 mm.

8. The system according to claim 7, wherein, The knitted fabric sheet has a thickness of approximately 9 mm to 11 mm.

9. The system according to claim 8, wherein, The knitted fabric sheet has a thickness of approximately 10.5 mm.

10. The system according to claim 1, wherein, The first yarn and the second yarn alternate between the first and second sides of the knitted fabric sheet to form rows on the first and second sides, wherein the rows interlock with the previous row to form stitches on the first and second sides.

11. A system comprising: First filter membrane; Second filtration membrane; and A permeation carrier is disposed between the first filter membrane and the second filter membrane. The permeation carrier comprises a knitted fabric, which includes a first yarn and a second yarn knitted together in a circular knitting pattern.

12. The system according to claim 11, wherein, At water pressures between 60 psi and 500 psi, the water flow rate through the system is approximately 100 ml / min to 250 ml / min.

13. The system according to claim 11, wherein, The knitted fabric has a thickness of approximately 5 mm to 15 mm.

14. The system according to claim 12, wherein, The knitted fabric has a thickness of approximately 9 mm to 11 mm.

15. The system according to claim 13, wherein, The knitted fabric has a thickness of approximately 10.5 mm.

16. A filter comprising: The complex comprises: —First filter membrane layer, —The second filter membrane layer, and —A permeation carrier disposed between the first membrane layer and the second membrane layer, the permeation carrier comprising a knitted fabric sheet comprising a first yarn and a second yarn knitted together in a circular knitted pattern, wherein the permeation carrier supports the first filter membrane layer and the second filter membrane layer; A feed spacer is disposed adjacent to the composite; and A perforated core, wherein the composite and the feed spacer are wound around the core, and the permeation carrier is a porous layer.

17. The filter of claim 16, further comprising a second complex, the second complex comprising: The third filtration membrane layer, The fourth filter membrane layer, and A second permeation carrier is disposed between the third membrane layer and the fourth membrane layer, the second permeation carrier comprising a second knitted fabric sheet, and wherein the second permeation carrier supports the third filter membrane layer and the fourth filter membrane layer.

18. The filter according to claim 16, wherein, The perforated core includes a perforated tube, which may be made of steel, stainless steel, polyvinyl chloride, acrylonitrile-butadiene-styrene, polypropylene, polyphenylene ether, polyphenylene oxide, or polysulfone.

19. The filter according to claim 16, wherein, At water pressures between 60 psi and 500 psi, the water flow rate through the filter is approximately 100 ml / min to 250 ml / min.

20. The filter according to claim 16, wherein, The first yarn and the second yarn comprise approximately 40 denier to 100 denier.

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