Integrated permeable channel membrane structure

Abstract

The invention relates to a filtration membrane envelope (3) comprising a 3D spacer fabric (7) with an upper surface (9) and a lower surface (10) held together and separated by a monofilament thread (11). The 3D spacer fabric is sandwiched between two membrane layers and defines permeable channels. The membrane layers are cast onto the upper and lower surfaces of the 3D spacer fabric, respectively. The upper and lower surfaces are at least partially embedded within the membrane layers to form upper and lower supports (13) and (14), characterized in that the supports have a minimum thickness of 100 μm.

Description

[Technical field]

[0001] The present invention relates to a filtration membrane envelope for use in water treatment, more particularly in water filtration and wastewater purification. [Background technology]

[0002] Integrated permeable channel (IPC) membranes have been used for the past few years in membrane bioreactors for wastewater purification. An IPC membrane made of a 3D woven textile is described in US Pat. No. 5,399,663.

[0003] However, a problem with currently known solutions on the market is that the layers tend to delaminate when used in filtration and backwashing modes, which obviously has a negative impact on the membrane's lifespan. In addition, currently known membranes that are cast onto woven or knitted textiles are susceptible to compression.

[0004] There remains a need for a filtration membrane envelope with improved mechanical properties so that it remains rigid, does not delaminate, and has good compression resistance during assembly and product use in filtration and backwash modes.

[0005] IPC membranes with spacer fabrics embedded in the membrane layer are also disclosed by the non-patent literature, US Pat. No. 5,399,633 and US Pat. No. 5,433,366. Patent Document 3 also relates to IPC membranes. The mechanical properties of the membrane are improved by optimizing the layers of said membrane. None of the above documents relates to an optimized membrane layer of a specific thickness. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] European Patent Publication No. 1625885 [Patent Document 2] International Publication No. 2021110716 [Patent Document 3] International Publication No. 20120981130 [Non-patent literature]

[0007] [Non-Patent Document 1] Doyen et al., 2009, Desalination, Volume 250, Issue 3 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention aims to overcome at least some of the problems and drawbacks mentioned above. It is an object of the present invention to provide a filtration membrane envelope having a thickness fine-tuning specification that eliminates these drawbacks. [Means for solving the problem]

[0009] The present invention and its embodiments serve to provide a solution to one or more of the above mentioned drawbacks. To this end, the present invention relates to a filtration membrane envelope as claimed in claim 1.

[0010] More specifically, the present invention provides a filtration membrane envelope having a 3D spacer fabric having upper and lower surfaces held together and separated by a monofilament yarn, the 3D spacer fabric being sandwiched between two membrane layers and defining permeable channels, the membrane layers being cast onto the upper and lower surfaces of the 3D spacer fabric, respectively, the upper and lower surfaces being at least partially embedded within the membrane layers to form upper and lower supports, the supports having a minimum thickness of 100 μm.

[0011] It has been found that the support allows the various components of the membrane envelope to be fixed well enough to prevent delamination even when subjected to high pressure, so that the envelope is able to retain its mechanical properties even after extensive use.

[0012] Preferred embodiments of the membrane envelope are set out in any of claims 2-11.

[0013] In a second aspect, the present invention relates to a water filtration module as claimed in claim 12. More particularly, the water filtration module described herein comprises an array of planar membrane envelopes.

[0014] In a third aspect, the present invention relates to the use according to claim 13. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1A shows a top view (FIG. 1B) and a side view (FIG. 1B) of a module according to an embodiment of the present invention. FIG. 1C shows a detail of a membrane envelope according to the present invention, consisting of a permeation channel inserted between two membrane layers. [Figure 2A] FIG. 2 shows a schematic diagram of a cross-section of a filtration membrane envelope according to an embodiment of the present invention; [Figure 2B] FIG. 2 is a scanning electron microscope (SEM) image of a cross section of an actual membrane. [Figure 2C] FIG. 2 is a scanning electron microscope (SEM) view of a cross section of a 3D spacer fabric used to manufacture a 3D membrane envelope according to one embodiment of the present invention. [Diagram 3] FIG. 1 shows a setup for determining delamination or delamination or delamination of a membrane envelope. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The present invention relates to a filtration membrane envelope for wastewater purification. Furthermore, the present invention relates to a filtration module comprising an array of planar membrane envelopes and to a method of using said filtration membrane envelope or filtration module.

[0017] Unless otherwise defined, all terms used in disclosing the present invention, including technical and scientific terms, have the meanings commonly understood by those of ordinary skill in the art to which the present invention belongs. By way of further guidance, definitions of terms are included to better understand the teachings of the present invention.

[0018] As used herein, the following terms have the following meanings:

[0019] The indefinite articles "a," "an," and "the," as used herein, refer to both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a section" refers to one or more sections.

[0020] "About," as used herein, refers to a measurable value such as a parameter, amount, duration, etc., and is meant to encompass a variation of ±20% or less, preferably ±10% or less, more preferably ±5% or less, even more preferably ±% or less, even more preferably ±0.1% or less, so far as such variations are appropriate for implementation in the disclosed invention. However, it should be understood that the value to which the modifier "about" refers is itself specifically disclosed.

[0021] As used herein, "Comprise," "comprising," "comprises," "comprises" is synonymous with "include," "including," "includes," "contain," "containing," "contains," and is an inclusive or open-ended term that specifies the presence of what follows, for example, a component, but does not exclude or preclude the presence of additional, non-reproduced components, features, elements, materials, steps that are known in the art or disclosed therein.

[0022] Moreover, the terms first, second, third, etc. in this specification and claims are used to distinguish between similar elements and are not necessarily used to describe a sequential or chronological order unless specified. The terms so used are interchangeable under appropriate circumstances, and it is to be understood that the embodiments of the invention described herein are capable of operating in other arrangements than described or illustrated herein.

[0023] The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within that range, as well as the recited endpoints.

[0024] The descriptions "weight %, "weight percent", "% wt" or "wt%" herein and throughout the specification, unless otherwise defined, refer to the relative weight of each component based on the total weight of the formulation.

[0025] The term "one or more" or "at least one", e.g., at least one member of a group of one or more members, will itself be apparent from further illustration, but the term specifically encompasses reference to any one of said members, or any two or more of said members, e.g., >=3, >=4, >=5, >=6 or >=7 of any of said members, etc., up to and including all of said members.

[0026] Unless otherwise defined, all terms used in disclosing the present invention, including technical and scientific terms, have the meaning commonly understood by those skilled in the art to which the present invention belongs. For further guidance, definitions of terms used in the description are included to better understand the teachings of the present invention. Terms or definitions used in this specification are provided solely to aid in the understanding of the present invention.

[0027] Throughout this specification, the phrase "one embodiment" or "an embodiment" means that at least one embodiment of the invention includes the particular feature, structure, or characteristic described in connection with that embodiment. Thus, the appearances of the phrase "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment, but may refer to the same embodiment. Furthermore, particular features, structures, or characteristics can be combined in any suitable manner in one or more embodiments, as would be apparent to one of ordinary skill in the art from this disclosure. Furthermore, although some embodiments described herein include some embodiments that are included in other embodiments but do not include other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments, as would be understood by one of ordinary skill in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0028] As used herein, "anchorage" is defined as the portion of the polymeric casting membrane in which the fabric is embedded.

[0029] "Filtration layer" as used herein is defined as the part of the membrane layer cast into the fabric that is not present in the fabric, but instead resides on top of the anchoring part. Usually, the filtration layer is defined by a certain porosity in the top layer formed by the precipitated polymer, typically with a pore size of 10 nm to 1 μm. As a result, the filtration layer can allow for the filtration of water.

[0030] In a first aspect, the present invention relates to a filtration membrane envelope comprising a 3D spacer fabric having upper and lower surfaces brought together and spaced apart by a monofilament yarn, said 3D spacer fabric being sandwiched between two membrane layers forming permeation channels, said membrane layers being cast onto said upper and lower fabric surfaces of said 3D spacer fabric, respectively, said upper and lower fabric surfaces being at least partially embedded in said membrane layers, thereby forming upper and lower anchoring parts, said anchoring parts having a minimum thickness of 100 μm, more preferably 150 μm, 200, 250, 300 μm. In a preferred embodiment, the fixing portion has a minimum thickness of 100 to 600 μm, preferably 100 to 450 μm, more preferably 100 to 400 μm, more preferably 100 to 350 μm, more preferably 100 to 300 μm, more preferably 100 to 250 μm, more preferably 100 to 200 μm, more preferably 100 to 150 μm.

[0031] In another embodiment, the total thickness of the fixing portion is 100 to 600 μm, 150 to 600 μm, 200 to 600 μm, 250 to 600 μm, 300 to 600 μm, 350 to 600 μm, 400 to 600 μm, 450 to 600 μm, 500 to 600 μm, preferably 550 to 600 μm.

[0032] As will be appreciated by those skilled in the art, the thickness of the fastening portion can be measured by many methods known in the art, such as scanning electron microscopy. In one embodiment, the thickness is an average value determined by measuring the thickness of the fastening portion at multiple points on the envelope. The absolute thickness at such a discrete point is defined by the distance between the extreme filament, loop, or thread of the fabric and the end point of the polymer embedded in the fabric, after which the fabric is free of polymer.

[0033] The anchoring portion is defined as a portion of the 3D spacer fabric embedded in either the upper or lower membrane layer. It has been observed that the membrane envelope with the anchoring portion should have a minimum thickness to make the membrane envelope robust enough to withstand the high pressures exerted during operational activities and backwashing. In this case, no peeling or delamination is observed. Furthermore, the inventors have observed that the membrane envelope of the present invention does not swell or expand its length or thickness when operated under submerged conditions.

[0034] Preferably, a filtration layer extends from each fastening portion in a direction facing the outside of the envelope, and the minimum thickness of the filtration layer is 50 μm, preferably 50-800 μm, more preferably 50-700 μm, more preferably 50-600 μm, more preferably 50-500 μm, more preferably 50-400 μm, more preferably 50-300 μm, more preferably 50-200 μm, more preferably 50-100 μm. Alternatively, the minimum thickness of the filtration layer is 400-500 μm. In one embodiment, the thickness of the filtration layer is the same on the lower and upper surfaces of the 3D spacer fabric. In a preferred embodiment, the thickness of the filtration layer may vary. For example, the upper surface may have a thicker filtration layer than the lower surface of the 3D spacer fabric. Alternatively, the lower surface may have a thicker filtration layer than the upper surface of the 3D spacer fabric.

[0035] In one embodiment, each membrane layer has a minimum total thickness of 150 μm, more preferably 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350 or 1400 μm. In another or further embodiment, each membrane layer has a total thickness of 150 to 1400 μm, preferably 150 to 1300 μm, more preferably 150 to 1200 μm, more preferably 150 to 1100 μm, more preferably 150 to 1000 μm, more preferably 150 to 900 μm, more preferably 150 to 850 μm, more preferably 150 to 850 μm, more preferably 150 to 800 μm, more preferably 150 to 700 μm, more preferably 150 to 600 μm, more preferably 150 to 550 μm, more preferably 150 to 500 μm, more preferably 150 to 450 μm, more preferably 150 to 400 μm, more preferably 100 to 350 μm, more preferably 150 to 300 μm, more preferably 150 to 250 μm. In another embodiment, the membrane layer has a total thickness of 150-1400 μm, 250-1400 μm, 300-1400 μm, 400-1400 μm, 450-1400 μm, 550-1400 μm, 600-1400 μm, 700-1400 μm, 800-1400 μm, 900-1400 μm, 100-1400 μm, 1200-1400 μm.

[0036] In one embodiment, the 3D spacer fabric has warp threads and weft threads that extend through the warp threads and are inserted above and below the warp threads. The warp threads are preferably aligned in a plane to define a stationary part and a membrane layer. The filtration layer is preferably represented by the area extending from the plane of the warp threads to the outside of the filtration membrane envelope, while the area including from the plane of the warp threads to the permeation channel was the stationary part. In another preferred embodiment, the weft threads that cross the warp threads belong to the stationary part.

[0037] The ratio of the thickness of the filtration layer to the thickness of the fixing part is preferably 1:10 to 3:1, more preferably 1:9 to 3:1, 1:8 to 3:1, 1:7 to 3:1, 1:6 to 3:1, 1:5 to 3:1, 1:4 to 3:1, 1:3 to 3:1, 1:2 to 3:1, or 1:1 to 3:1.

[0038] In one embodiment, the ratio of the thickness of the filtration layer to the thickness of the fixing part is 1:10 to 3:1, 1:10 to 2:1, or 1:10 to 1:1.

[0039] Preferably, the total thickness of the filtration membrane jacket is between 1.8 and 6 mm, preferably between 1.8 and 5.5 mm, or between 1.8 and 5 mm, preferably between 1.8 and 4.5 mm, preferably between 1.8 and 4 mm, preferably between 1.8 and 3.5 mm, preferably between 1.8 and 3 mm, preferably between 1.8 and 2.5 mm, preferably between 1.8 and 2.5 mm.

[0040] In one embodiment, the total thickness of the entire filtration membrane envelope is 1.9-6 mm, 2-6 mm, 2.5-6 mm, 3-6 mm, 3.5-6 mm, 4-6 mm, 4.5-6 mm, 5-6 mm, 5.5-6 mm.

[0041] The above-defined thickness of the fixing part and the thickness of the membrane and filtration layer ensure the outstanding properties of the membrane envelope. Said membrane envelope is robust, highly resistant to compression and flatness, and does not expand its length or width when operated under immersion conditions. Moreover, they show less than 10% peeling or delamination of the spacer fabric and membrane layer when exposed to a pressure of 2 bar, preferably they show less than 5% peeling or delamination, preferably less than 1% peeling or delamination, even 0%. The percentage of peeling or delamination is understood as the amount of membrane layer surface that peels off from the 3D spacer fabric.

[0042] In one embodiment, the compression of the membrane envelope is less than 5% when exposed to a static pressure of 0.5 bar, preferably 0.1 bar, more preferably 0.2 bar, more preferably 0.3 bar, more preferably 0.4 bar, more preferably 0.5 bar, more preferably 0.6 bar, more preferably 0.7 bar, more preferably 0.8 bar, more preferably 0.9 bar, more preferably 1 bar, more preferably 2 bar.

[0043] In one embodiment, the membrane envelope exhibits less than 5%, preferably less than 4%, more preferably less than 3% when exposed to a static pressure of up to 0.5 bar.

[0044] The 3D spacer fabric present within the filtration membrane envelope forms a permeation channel, which is a free space for liquid extraction between the two parallel membrane layers of the filtration membrane envelope.

[0045] In one embodiment, the permeate channel of the membrane envelope has a channel thickness of 1-4 mm, more preferably 1.5-3 mm, more preferably 1.8-2.8 mm. When the above conditions exist, the pressure drop in the permeate channel is negligible during operation of the module.

[0046] The permeation channel comprises an open space formed by the 3D spacer fabric. To ensure optimal flow distribution through the membrane envelope, the percentage of open space in the permeation channel is 80-99%, more preferably 85-99%, more preferably 90%-99%.

[0047] Preferably, the 3D spacer fabric is of the knitted, woven or non-woven type. In a preferred embodiment, the 3D spacer fabric has a woven structure. In one embodiment, the 3D spacer fabric preferably comprises a material selected from the group consisting of polyester, nylon, polyamide, polyphenylene sulfide, polyethylene and polypropylene. During the weaving process, the longitudinal or lengthwise longitudinal threads are held stationary under tension on a frame or loom while the transverse weft threads are pulled through the longitudinal threads and inserted above and below the longitudinal threads.

[0048] The membrane envelope can be produced by providing a 3D spacer fabric comprising an upper and lower fabric separated by a predetermined distance by a monofilament yarn, and then providing a membrane layer on the upper and lower fabrics such that a number of regions are embedded in the membrane layer. The step of providing a membrane layer preferably includes a casting step using a casting material, and a step of solidifying the casting material to form a membrane layer in which the fabric is embedded. This process is known as "immersion precipitation", in which a polymer plus solvent (polymer solution) is cast onto a support layer and then immersed in a coagulation bath containing a non-solvent. Precipitation occurs due to solvent and non-solvent exchange.

[0049] In a preferred embodiment of the membrane disclosed herein, during the casting process, a polymer solution is applied to the upper and lower sides of the 3D spacer fabric to form the upper and lower surfaces of the membrane. More specifically, the polymer is applied by an injection process by a casting module comprising a casting head. Before or during the casting process, the thickness and / or taper change of the fabric is measured and the distance between the 3D fabric and the casting head is adjusted based on the measurements.

[0050] 3D woven fabrics used to manufacture filtration membranes lack surface uniformity and generally vary in thickness and roughness. The result of the weaving process is often a tapered textile. It was found that by measuring the thickness variation of the 3D spacer fabric in real time and adjusting the casting head accordingly, a membrane with a uniform cast layer across its entire surface could be obtained.

[0051] Preferably, the thickness of the 3D spacer fabric is measured over its entire length before said fabric is lowered in the casting module. Said measurement is used to adjust the distance between the 3D spacer fabric and the casting head. By adjusting said distance, a uniform cast layer is achieved over the entire membrane, which takes into account thickness variations and / or tapers of the fabric.

[0052] In one embodiment, the casting step is carried out on a fabric that is vertically positioned and that descends during casting into a precipitation bath, which preferably contains water.

[0053] The casting process can be a one-step process or a multi-step process where a polymer is cast and precipitated onto a material, followed by a second round of casting or coating.

[0054] The membrane layer undergoes a process of densification during the solidification process. Due to the casting process used, the porosity of the membrane layer gradually increases in the direction of the polymer penetration of the polymer in the 3D fabric. As a result, the membrane layer contains two sections: a filtration layer with a relatively fine or small pore size and a fixed part with a relatively large pore size. The filtration layer preferably has pores with a size of 10 nm to 1 μm, while the fine pore size of the fixed part has macrovoids.

[0055] The casting material may include a hydrophilic filler material selected from the group consisting of HPC, CMC, PVP, PVP, PVA, PVAc, PEO, TiO2, HfO2, Al2O3, ZrO2, Zr3(PO4)4, Y2O3, SiO2, perovskite oxide materials, and SiC, an organic binder material selected from the group consisting of PVC, C-PVC, PSf, PESU, PPS, PU, ​​PVDF, PI, PAN, and grafted variations thereof, and a solvent selected from the group consisting of NMP, DMF, DMSO, or DMAC, or mixtures thereof. Solvent-free processing may be considered as well. It will be clear to one skilled in the art that other manufacturing methods are known in the art and may be applied.

[0056] In one embodiment, the thickness of the resulting fabric having a cast membrane layer is measured again after said fabric is removed from the plating bath.

[0057] The inventors have surprisingly observed that the membrane envelope, in which the displacement of the spacer fabric during the casting process is taken into account, controls the thickness of the layers, e.g., anchoring, filtration layers, permeation channels, and ensures optimal mechanical properties of said IPC membranes, such as resistance to compression, being robust to peeling, and not expanding their length or width when operated under immersion conditions. Prior art membranes do not have the superior mechanical properties of the membranes of the present invention, and the thickness of the layers and the ratio between said layers are not known for these prior art membranes. Moreover, prior art membranes are obtained by other manufacturing methods and therefore cannot achieve the properties of the membranes disclosed herein.

[0058] Preferably, the membrane envelope is planar. The membrane envelope may further comprise a sealant around the planar membrane envelope arranged to prevent direct fluid transfer from or to the permeate channel without passing through the membrane layer, and may comprise an inlet / outlet port connection fluidly connected to the permeate channel, the inlet / outlet port connection being provided with at least one edge around the periphery. Each membrane envelope may have an end covered by a U-shaped cap, the cap being a metal cap, preferably a stainless steel cap.

[0059] In a second aspect, the invention relates to a water filtration module comprising an array of planar membrane envelopes according to any of the above-mentioned embodiments.

[0060] In a third aspect, the present invention relates to the use of a membrane envelope or a filtration module according to the above description for the purification and / or filtration of fluids such as water and / or wastewater. The membrane envelope or the filtration module can be used for the filtration and / or purification of surface water or wastewater. However, it is clear that the invention is not limited to this application. The membrane envelope or the filtration module according to the present invention can be applied to the treatment of any kind of liquid source.

[0061] Preferably, the membrane envelope or water filtration module is used in operation with a backwash inter-membrane pressure of at least 300 mbar. Due to the nature of the membrane envelope, the membrane or module is particularly useful to be cleaned by backwashing, backpulsing or backwashing. In one embodiment, said filtration module can be backwashed with a pressure of at least 20 mbar, more preferably at least 30 mbar, more preferably at least 40 mbar, more preferably at least 50 mbar, more preferably at least 60 mbar, more preferably at least 70 mbar, more preferably at least 80 mbar, more preferably at least 90 mbar, more preferably at least 100 mbar, more preferably at least 200 mbar, more preferably at least 300 mbar, more preferably at least 400 mbar, at least 500 mbar, at least 1 bar, at least 2 bar. This high pressure backpulsing is possible without compromising the mechanical cleaning efficiency of the backwash. During this operation, the membrane, more particularly the pores present, are cleaned from any debris filtered from the water. This may also include chemically enhanced backwash cleaning, where the pores are chemically cleaned by a volumetric flow of chemicals across the membrane envelope. For either operation, this again requires optimal and even flow.

[0062] The membrane envelope or water filtration module described herein can be used for microfiltration, ultrafiltration, MBR, pervaporation, membrane distillation, supported liquid membrane and / or pertraction.

[0063] Advantageously, it has been determined that the membrane envelope of the present invention does not expand in length or width when immersed. The structure of the membrane envelope ensures that, with the 3D spacer fabric and monofilament yarn embedded in the membrane layer, said membrane envelope maintains its shape and dimensions without any expansion when immersed in liquid. This allows the membrane envelope to stay in place during water filtration operations without the use of additional means for membrane stabilization, such as comb-like structures.

[0064] The invention will now be described in more detail with reference to non-limiting examples.

[0065] [Figure description] FIG. 1 shows a top view (FIG. 1A) and a side view (FIG. 1B) of a module 1 according to an embodiment of the present invention. The module 1 comprises a rectangular rigid holder 2 with several planar membrane envelopes 3 in the holder 2, arranged side by side and spaced apart. Caps 4 may be provided on the top and bottom of the membrane envelope 3 to ensure the rigidity and positioning of the membrane. By way of example, the module may contain 65 to 107 membrane envelopes. The module 1 is provided with manifolds 5, 6 that regulate the ingress and egress of water. The envelope is composed of a 3D spacer fabric forming a permeation channel. The 3D spacer fabric is lined by membrane layers 8, 17 that cover the 3D spacer fabric on both sides. A schematic diagram of a section of the envelope 3 is shown in FIG. 1C. The permeation channel formed by the 3D spacer fabric 7 has an open space of 80 to 99% formed by the nature of the 3D spacer fabric. Advantageously, the thickness of the spacer fabric part of the membrane envelope is 1.5 to 3 mm.

[0066] FIG. 2A shows a schematic diagram of a cross section of a filtration membrane envelope according to an embodiment of the invention. The membrane envelope 3 is obtained by casting the upper surface 9 and the lower surface 10 of a 3D spacer fabric 7 with membrane layers 8, 17. Between the two parallel membrane layers of the filtration membrane envelope, permeation channels 12 for liquid extraction are formed. The 3D spacer fabric is made by monofilament yarns 11, 18, such as weft yarns 11 and warp yarns 18. The 3D spacer fabric is embedded in a number of regions 15 in the membrane layer, forming upper fastenings 13 on the upper surface of the 3D spacer fabric and lower fastenings 14 on the lower surface of the 3D spacer fabric. A filtration layer 16 extends from each fastening in a direction facing the outside of said filtration membrane envelope.

[0067] Figure 2B is a scanning electron microscope (SEM) view of a cross section of an actual membrane. The plane of the weft defines the anchoring and filtration layers. The scale bar represents 4 mm.

[0068] FIG. 2C is a scanning electron microscope (SEM) image of a cross section of a 3D spacer fabric used to manufacture a 3D membrane envelope according to the present invention.

[0069] Figure 3 represents the setup for measuring the peeling or delamination of the membrane envelope, where a is the air valve, a is the pressure gauge, b is the drain valve, c is the air pressure regulator, d is the pressure gauge, e is the oil reservoir, f is the valve, g is the membrane test cell, and off is the pressure reducing valve.

[0070] [Example] The invention will now be further illustrated with reference to the following examples. The invention is in no way limited to the examples given or to the embodiments shown in the figures.

[0071] Example 1: Resistance of filtration membrane envelope to pressure Filtration Membrane Envelope The filter is subjected to 2 bar air pressure from the inside, mimicking the backwash mode. Three types of filtration membrane envelopes are used, with different membrane layers. The settings are as follows: The membrane 1 has a membrane layer (thin membrane layer) with a thickness of less than 150 μm and a fixing part with a thickness of less than 100 μm. The membrane 2 has a membrane layer with a thickness of more than 1400 μm (thick membrane layer) and a fixing part with a thickness of more than 600 μm. The membrane 3 is a membrane according to the invention having a membrane layer (membrane layer according to the invention) with a thickness of 150 to 1400 μm and a fixing part with a thickness of 100 to 600 μm.

[0072] The delamination or detachment of the spacer fabric and membrane layers at an air pressure of 2 bar was measured.

[0073] Results: The delamination or peeling rate is inversely proportional to the thickness of the membrane layer. Membranes 2 and 3 with thick membrane layers and membrane layers according to the invention do not delaminate, while membrane 1 with thin membrane layers does not. Membrane 2 prevents delamination or detachment, but such thick membrane layers over 1400 μm are not cost-effective, in contrast to the membranes of the present invention, which ensure robust fixation and sufficient membrane layers to prevent delamination or detachment at the same time are economical.

[0074] [Example 2: Compression test of filtration membrane envelope] The samples for the preparation of the filtration membrane are subjected to a constant static pressure in the range of 0-2 bar (e.g. 0.5 or 1 bar) mimicking suction mode filtration. The settings are as follows: - a filtration membrane envelope according to the invention, having a membrane layer (membrane layer according to the invention) having a thickness of 150 to 1400 μm and a fixing part having a thickness of 100 to 600 μm; - 3D woven textiles used to make the filtration membrane envelope according to the invention - Conventional filtration membranes - Prior art knitted fabrics used to make filtration membranes

[0075] The compressibility of the test specimen is determined.

[0076] Results: The filtration membrane envelope and the 3D woven textile used to make it exhibit significantly lower compression than the prior art membranes and prior art knitted textiles.

[0077] Example 3: Determination of layer thickness of filtration membrane envelope

[0078] Scanning electron microscopy (SEM) was used to determine the thickness of the envelope layer of the filtration membrane. The membrane samples were cut into 6 x 20 mm pieces and coated with a conductive platinum (Pt) layer to prevent static buildup on the top and sides of the samples.

[0079] Electron micrographs were recorded on an FEI Quanta FEG microscope using secondary electrons (SE) and / or backscattered electrons (BSE). By using SE-electrons, mainly the surface structure is displayed, whereas by using BSE-electrons the recording mainly shows the difference in (electron) density of the different materials. This means that areas with higher density and / or higher concentration of heavier elements appear the brightest, and areas with lower density material appear darker.

[0080] The samples were placed with the side view facing upwards. Four pictures were taken at 13x magnification from four different samples.

[0081] In SEM micrographs, the cuts of the warp threads could be seen in cross section as round objects protruding from the membrane structure and arranged in one plane by design (Figure 2B). The diameter of the warp threads was 150 μm. The plane of the warp threads defined the anchoring part and the filtration layer. The filtration layer was the area extending from the plane of the warp threads to the outside of the filtration membrane envelope, while the area including from the plane of the warp threads to the permeation channel was the anchoring part.

[0082] The thickness of each layer was measured once for each micrograph based on the magnification used (Figure 2B), and the average of four samples was determined.

[0083] Example 4: Determination of the percentage of open space in a transmission channel The porosity of the transmission channel is 1 cm of the transmission channel. 3 The results were evaluated by determining the percentage of open space per well.

[0084] The membrane envelope was cut to the center and placed filtration layer down with the cut monofilament threads attached on top.

[0085] A 1 x 1 cm frame was placed on the sample and examined under a stereomicroscope (Zeiss Stemi 2000-C). The number of protruding monofilament threads was then determined. The volume occupied by the monofilament threads was determined based on their number and diameter (150 um) and subtracted from the total volume of the permeation channel. The percentage of free space was then calculated based on the difference.

[0086] It has a transmission channel thickness of 2 mm and contains 168 threads per cm 2 For the membrane envelopes counted at , the following was calculated: a) Volume of one monofilament thread = 3.14 x (0.0075 cm) 2 ×0,2cm = 0.0000353 cm 3 b) Total volume of monofilament yarn = 168 x 0.0000353 = 0.0059 cm 3 c) Total volume of the permeation channel = 1cm x 1cm x 0.2cm = 0.2 cm 3 d) Vacancy rate = (0.2 cm 3 -0.0059cm) / 0.2 cm 3 ×100%=97%

[0087] [Example 5: Determination of compression] Compression testing was performed using ISO standard ISO 5084. The compression was measured using a Twing Albert Frank tensile testing machine type 81828 at 25° C. and 65% relative humidity.

[0088] A piece of the 3D spacer fabric was cut into a disk with a diameter of 20 mm.

[0089] Each sample of the 3D spacer fabric was subjected to a series of pressures of gradually increasing intensity from 0 to 1.5 bar (Table 1). The pressure was applied for 30 seconds each time. The thickness of the hard disk was measured before each test and again after each compression test.

[0090] The thickness was compared with the average original thickness at the end of the compression test, and the compression rate was expressed as a percentage using a formula.

number

[0091] [Example 6: Determination of membrane envelope peeling or delamination] Peel or delamination tests were performed in a setup that included pressurized medium viscous oil (50 cSt) and a membrane module with a filtration layer attached to the bottom of the membrane test cell, as shown in FIG.

[0092] The setup workflow was as follows: 1: The oil reservoir was pressurized by introducing air through the valve (in). 2: The air supply pressure was measured using a manometer (a). 3: The pressure in the oil container (e) was measured by a pressure gauge (d). 4: Valve (f) was opened to release pressure onto the membrane module containing the membrane test cell (g). 5: Using regulator (c), gradually increase the air pressure from 0 to 4 bar at 0.1 bar / 5 seconds. 6: When the maximum pressure was reached, the membrane was pushed or peeled off from the support or ruptured into the membrane, releasing all the oil through the valve (outlet). 7: Pressure at which membrane rupture was recorded 8: After the test, the system was depressurized through valve (off) and the oil accumulated between the “in” valve and the oil container was drained through valve (b). [Explanation of symbols]

[0093] 1: Module 2: Holder 3: Membrane envelope 4: Cap 5,6: Manifold 7: 3D Spacer Fabric 8, 17: Membrane layer 9: Top surface of 3D spacer fabric 10: Underside of 3D spacer fabric 11: Monofilament weft 12: Transparent channel 13: Upper fixing part 14: Lower fixing part 15: Monofilament yarn embedded area 16: Filtration layer 18: Monofilament warp

Claims

1. 1. A filtration membrane envelope comprising a 3D spacer fabric having monofilament warp threads that are gathered together and run longitudinally, and weft threads that pass through the warp threads and are inserted above and below the warp threads, the 3D spacer fabric having upper and lower surfaces spaced apart by the weft threads, the 3D spacer fabric being sandwiched between two membrane layers that define permeable channels, the membrane layers being cast onto the upper and lower surfaces of the 3D spacer fabric, respectively, and the upper and lower surfaces being at least partially embedded within the membrane layers to provide an upper fixation. a filtration membrane envelope, characterized in that the filtration membrane envelope has a lower fixing portion and a lower fixing portion, the warp threads being aligned in a plane and defining the fixing portions and the membrane layer, a filtration layer extending from the plane of the warp threads of each of the fixing portions in a direction that directs the outer surface of the membrane envelope toward the exterior of the membrane envelope, each of the filtration layers having a minimum thickness of 50 μm, each of the fixing portions having a minimum thickness of 100 μm determined by scanning electron microscopy (SEM) in a region including the plane of the warp threads and the permeable channels, and the fixing portions having a thickness ratio of 1:10 to 3:

1.

2. 2. The filtration membrane envelope according to claim 1, wherein the filtration layer extending from each of the fixing portions is 50 to 800 μm.

3. 3. The filtration membrane envelope of claim 2, wherein each of the membrane layers has a total minimum thickness of 150 μm.

4. 4. The filtration membrane envelope of claim 3, wherein the permeable channel has a channel thickness of 1.5 to 3 mm.

5. 5. The filtration membrane envelope of claim 4, wherein the overall thickness of the entire membrane envelope is between 1.8 and 6 mm.

6. 6. The filtration membrane envelope of claim 5, wherein the permeable channel comprises an open space formed by the 3D spacer fabric.

7. 7. The filtration membrane envelope of claim 6, wherein the percentage of open space within the permeable channels is between 80 and 99%.

8. 8. The filtration membrane envelope of claim 7, wherein the 3D spacer fabric is a woven, non-woven or knitted fabric.

9. A water filtration module comprising an array of planar filtration membrane envelopes according to claim 8.

10. Use of a filtration membrane envelope or a water filtration module according to any one of claims 1 to 9 for water filtration and / or wastewater purification.

Images