Membrane element regeneration method and membrane module

Abstract

The invention relates to a regeneration method of a membrane element and a membrane module. Provided are a method for regenerating a membrane element and a membrane module using the regenerated membrane element, with which it is possible to reduce waste caused by the used membrane element and save resources, and to recover the separation function, without having to change the structure of the membrane element to be regenerated. The present invention is a method for regenerating a membrane element for manufacturing a regenerated membrane element using a part of a used membrane element, the method comprising: a step for cutting off at least both side sealing parts of the used membrane element; a step for expanding the cut-off film leaf and cutting off at least the outer peripheral sealing part of the film leaf; a step for replacing at least the separation membrane of the expanded and cut membrane leaf with a new separation membrane; and a step for forming both-side sealing parts and an outer-peripheral-side sealing part for sealing both-side end parts and outer-peripheral-side end parts in the axial direction of the replaced membrane blades, thereby obtaining a regenerated membrane element.

Description

Technical Field

[0001] The present invention relates to a method for regenerating membrane elements by using a portion of a used membrane element to manufacture a regenerated membrane element, and to a membrane assembly using the obtained regenerated membrane element. Background Technology

[0002] A typical spiral membrane element has the following structure: a permeation-side spacer sandwiched between opposing separation membranes, and multiple membrane leaves having a two-sided sealing portion and an outer peripheral sealing portion that seal the two-sided ends and the outer peripheral ends in the axial direction; a supply-side spacer sandwiched between the aforementioned membrane leaves; and a perforated central tube wound with the aforementioned membrane leaves and the aforementioned supply-side spacer.

[0003] For spiral membrane elements like these, over the years, deterioration and fouling of the membrane surface occur, resulting in a gradual decline in performance. To address membrane fouling, physical methods such as flushing to increase the flow rate of the supplied liquid side or chemical cleaning can be used to physically remove contaminants, while chemical cleaning with chemicals can restore performance to some extent. However, there are limits to this recovery, necessitating replacement of the membrane element itself.

[0004] The disposal of used membrane elements after replacement is a significant challenge. Landfill disposal has limited capacity, and membrane elements, being mostly plastic, cannot decompose underground, thus leaving semi-permanent residues. Therefore, it is desirable to minimize waste generated from used membrane elements. This also applies to incineration.

[0005] As a technology for reusing membrane elements after use, there are technologies such as making the outer casing of a spiral membrane element into a reusable structure (Patent Documents 1-2), making the anti-stretch material into a reusable structure (Patent Document 3), making the central tube into a reusable structure (Patent Document 4), and so on.

[0006] However, these technologies all require modifications to the structure of the spiral membrane element based on the existing structure, and cannot reuse the spiral membrane elements that have been used up so far.

[0007] On the other hand, Patent Document 5 proposes a method for reusing spiral membrane elements with conventional structures after use, which involves removing the separation functional layer of the RO membrane element with an acidic aqueous solution or the like and regenerating it into a UF membrane that serves as a porous support.

[0008] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2000-15063 Patent Document 2: Japanese Patent Application Publication No. 2012-183527 Patent Document 3: Japanese Patent Application Publication No. 2008-149322 Patent Document 4: Japanese Patent Application Publication No. 11-267467 Patent Document 5: Japanese Patent Application Publication No. 11-156169 Summary of the Invention

[0009] The problem that the invention aims to solve However, the regeneration method described in Patent Document 5 cannot regenerate the used spiral membrane element into the same RO membrane element as before regeneration, thus there is a problem that the original separation membrane function cannot be restored.

[0010] Therefore, the object of the present invention is to provide a method for regenerating membrane elements and a membrane assembly using the obtained regenerated membrane elements, which can reduce waste caused by the used membrane elements and save introduced resources without changing the structure of the membrane elements to be regenerated, and can restore the separation function.

[0011] Methods for solving problems The above objectives can be achieved by the present invention as described below.

[0012] [1] A membrane element regeneration method, which is a membrane element regeneration method that uses a portion of a used membrane element to manufacture a regenerated membrane element, wherein, The aforementioned used membrane element comprises: a permeation-side spacer sandwiched between opposing separation membranes, and multiple membrane leaves having side-sealing portions and an outer-peripheral sealing portion that seals the two side ends and the outer peripheral end in the axial direction; a supply-side spacer sandwiched between the aforementioned membrane leaves; and a perforated central tube wound with the aforementioned membrane leaves and the aforementioned supply-side spacer. The aforementioned regeneration methods include: The process of cutting off at least the aforementioned two sealing portions of the membrane element after it has been used; The process of unfolding the removed membrane leaf and removing at least the outer peripheral sealing portion of the membrane leaf; The process of replacing at least the aforementioned separation membrane with a new separation membrane after the membrane leaf has been unfolded and removed; and The process of forming a two-sided sealing part and an outer peripheral sealing part to seal the two sides and the outer peripheral side of the replaced membrane leaf in the axial direction, thereby obtaining a regenerated membrane element.

[0013] According to the membrane element regeneration method of the present invention, the structure of the used membrane element to be regenerated is the same as that of conventional membrane elements. Therefore, it is possible to replace at least the separation membrane that is difficult to restore in its current state with a new separation membrane without changing the structure of the membrane element. Thus, the separation function can be restored while at least a portion of other components are reused. Furthermore, since at least a portion of the components can be reused, the amount of new plastic input is reduced, thereby conserving valuable petroleum resources. As a result, a membrane element regeneration method can be provided that reduces waste from used membrane elements and conserves introduced resources without changing the structure of the membrane element to be regenerated, and can restore the separation function.

[0014] [2] The membrane element regeneration method as described in [1], wherein when replacing with the aforementioned new separation membrane, the aforementioned supply-side spacer is replaced with a regenerated supply-side spacer that has been cleaned to remove pollutants, or replaced with a new supply-side spacer.

[0015] By replacing the supply-side spacer with a regenerated one that has had contaminants removed through cleaning, or by replacing it with a new supply-side spacer, the function of the supply-side spacer, which is difficult to restore in the condition of the membrane element, can be restored.

[0016] [3] The membrane element regeneration method as described in [1] or [2], wherein the membrane element after use has an outer casing material, and the outer casing material is removed after the sealing portions on both sides are cut off.

[0017] By removing the outer material after cutting off the sealing portions on both sides, the outer material can be easily removed even in structures where the outer material and end components are integrated.

[0018] [4] The method for regenerating a membrane element as described in any one of [1] to [3], wherein the aforementioned central tube of the previously used membrane element is replaced with a regeneration central tube whose length has been adjusted by cutting, or is replaced with a new central tube.

[0019] Regarding the permeate side spacer after the sealing portions on both sides are removed and the separation membrane is replaced, the length in the axial direction becomes shorter. However, by replacing it with a regeneration center tube whose length has been adjusted by cutting or by replacing it with a new center tube, it can be used as a center tube of appropriate length for membrane element regeneration.

[0020] [5] A membrane assembly, which comprises a membrane element and a container housing the membrane element, wherein, The aforementioned membrane element is a regenerated membrane element manufactured using a portion of a used membrane element, wherein the length of the separation membrane in the axial direction has been shortened. In the aforementioned membrane module, the aforementioned container contains one or more of the aforementioned regenerated membrane elements that are more numerous than the number of the aforementioned used membrane elements.

[0021] According to the membrane assembly of the present invention, even when using a regenerated membrane element whose length in the axial direction of the separation membrane is shortened, the decrease in the total membrane area can be suppressed because more than one regenerated membrane element than the number of used membrane elements is housed in the container. Furthermore, the regenerated membrane element whose length in the axial direction of the separation membrane is shortened can be a regenerated membrane element that reuses at least the permeate-side spacer, the supply-side spacer, and the central tube as needed. As a result, a membrane assembly can be provided that can use a regenerated membrane element that reuses at least the permeate-side spacer while suppressing the decrease in the total membrane area.

[0022] [6] The membrane assembly as described in [5], wherein the aforementioned regenerated membrane elements are connected to each other by an interconnect with anti-stretch function, or the aforementioned regenerated membrane elements with anti-stretch function are connected to each other by an interconnect.

[0023] When the regenerated membrane elements are connected to each other by interconnects with anti-stretching function, it is not necessary to install anti-stretching material on the regenerated membrane elements, and a structure that is advantageous for suppressing the decrease in total membrane area can be made. In addition, when the aforementioned regenerated membrane elements with anti-stretching function are connected to each other by interconnects, the decrease in total membrane area can also be suppressed by reducing the thickness of the anti-stretching material of the regenerated membrane elements.

[0024] Invention Effects According to the membrane element regeneration method of the present invention, a method for regenerating membrane elements can be provided that can reduce waste caused by the used membrane element and save introduced resources without changing the structure of the membrane element to be regenerated, and can restore the separation function.

[0025] According to the membrane assembly of the present invention, it is possible to provide a membrane assembly that can use a regenerated membrane element that reuses at least the permeate side spacer while suppressing the overall membrane area reduction. Attached Figure Description

[0026] Figure 1A This is a perspective view showing a portion of an example of a membrane element that is the object of the regeneration method for the membrane element of the present invention.

[0027] Figure 1B This is a perspective view showing a portion of the main part of an example of a membrane element that will be the object of the membrane element regeneration method of the present invention, after being cut off.

[0028] Figure 2AThis is a top view showing an example of the process of cutting off the sealing portions on both sides.

[0029] Figure 2B This is an unfolded diagram showing an example of the process of cutting off the sealing portions on both sides, and it is a diagram showing one of the membrane leaves unfolded.

[0030] Figure 3 This is an unfolded diagram showing an example of the process of cutting off the outer peripheral sealing portion, and it is a diagram showing one of the membrane leaves unfolded.

[0031] Figure 4A This is an unfolded diagram showing an example of the process of replacing the membrane with a new one, and it is a diagram showing one of the membrane leaves before replacement.

[0032] Figure 4B This is an unfolded diagram showing an example of the process of replacing a new separation membrane. It is a diagram showing one of the membrane blades being replaced unfolded. The imaginary line continuous with the separation membrane shows the state in which the separation membrane is folded.

[0033] Figure 5A This is a perspective view illustrating an example of the process of replacing a new separation membrane, showing the insertion of a new separation membrane into multiple permeation-side spacers and the appearance of supply-side spacers.

[0034] Figure 5B This is a perspective view illustrating an example of the process of replacing the separation membrane with a new one, showing the state in which multiple new separation membranes and supply-side spacers are inserted into multiple permeation-side spacers.

[0035] Figure 6A This is a top view showing an example of a regenerated membrane element with a sealing portion cut off at the end, showing the state before the cut-off.

[0036] Figure 6B This is a top view showing an example of a regenerated membrane element with a sealing portion cut off at the end, showing the state after the cut-off.

[0037] Figure 7A This is a cross-sectional view illustrating an example of the regenerated membrane element and interconnect used in the membrane assembly of the present invention.

[0038] Figure 7B This is a cross-sectional view showing an example of the main parts of the membrane assembly of the present invention.

[0039] Figure 8A This is a cross-sectional view showing another example of the regenerated membrane element and interconnect used in the membrane assembly of the present invention.

[0040] Figure 8B This is a cross-sectional view showing another example of the main part of the membrane assembly of the present invention.

[0041] Figure 9A This is a cross-sectional view showing another example of the regenerated membrane element and interconnect used in the membrane assembly of the present invention.

[0042] Figure 9B This is a cross-sectional view showing another example of the main part of the membrane assembly of the present invention.

[0043] Figure 10 This is an unfolded diagram showing another example of the process of cutting off the outer peripheral sealing portion, and it is a diagram showing one of the membrane leaves unfolded.

[0044] Figure 11A This is an unfolded diagram showing another example of the process of replacing the separation membrane with a new one, which is an unfolded diagram showing one of the membrane leaves before replacement.

[0045] Figure 11B This is an unfolded diagram showing another example of the process of replacing the membrane with a new one; it is a diagram showing one of the membrane blades being replaced unfolded; the imaginary line continuous with the membrane shows the state in which the membrane is folded.

[0046] Explanation of reference numerals in the attached figures 1: Separation membrane 1': New separation membrane 2: Supply-side spacers 2': New supply-side spacer 3: Through the side spacer 5: Central tube 11: Side sealing sections 12: Peripheral sealing part 15: Exterior materials 21: Interconnector A1: Axial direction C1~C3: Cutting wire UE: Used membrane element RE: Regenerated Membrane Elements R: Wrapped body L: Membranous leaf V: Container Detailed Implementation

[0047] (Membranes regeneration method) The membrane element regeneration method of the present invention is a method for manufacturing a regenerated membrane element using a portion of a used membrane element. The membrane element in question is a spiral-shaped membrane element.

[0048] Figure 1A This is a perspective view showing a portion of an example of a membrane element that is the object of the regeneration method for the membrane element of the present invention. Figure 1BThis is a perspective view showing a portion of the main part of an example of a membrane element that will be the object of the membrane element regeneration method of the present invention, after being cut off.

[0049] That is, for example, such as Figures 1A-1B As shown, a used membrane element UE, for example, includes: a plurality of membrane leaves L having a permeation-side spacer 3 sandwiched between opposing separation membranes 1, and having a two-sided sealing portion 11 and an outer peripheral sealing portion 12 that seal the two-sided ends and the outer peripheral ends in the axial direction A1; a supply-side spacer 2 sandwiched between the membrane leaves L; and a perforated central tube 5 wound with the membrane leaves L and the supply-side spacer 2. First, this used membrane element will be described.

[0050] (The membrane element after use) As for membrane elements that have been used up, examples include membrane elements that cannot be restored to their function even after chemical cleaning, specifically those in the following states: (1) In terms of salt retention performance, even after repeated chemical cleaning (external or internal cleaning), the permeate flow rate is less than 50% of the initial value, and the salt permeate rate is more than 10% (the salt retention rate is less than 90%); (2) When comparing the weight of the membrane element with that of a new product, even after repeated chemical cleaning (external or internal cleaning), the accumulated deposits increase the weight by more than 25% of the initial value, making it impossible to remove contaminants.

[0051] The membrane element UE after use only needs to have: a permeation-side spacer 3 sandwiched between opposing separation membranes 1, and multiple membrane leaves L having a two-sided sealing portion 11 and an outer peripheral sealing portion 12 that seal the two-sided ends and the outer peripheral ends in the axial direction A1; a supply-side spacer 2 sandwiched between the membrane leaves L; and a perforated central tube 5 wound with the membrane leaves L and the supply-side spacer 2, then any known spiral membrane element can be used.

[0052] In this specification, the membrane leaf L wound around the central tube 5 and the supply-side spacer 2 are referred to as the winding body R. Figure 1A As shown, the membrane element UE is typically a structure with an outer material 15 on the outer periphery of the winding body R.

[0053] The membrane element UE is provided with two side sealing portions 11 and an outer peripheral sealing portion 12 as sealing portions to prevent mixing between the supply side flow path and the permeation side flow path, but if Figure 1BAs shown, in the sealing section, the two side sealing sections 11 are formed by sealing the two ends of the membrane leaf L in the axial direction A1 with an adhesive. The outer peripheral sealing section 12 is formed by sealing the end of the outer peripheral front end of the membrane leaf L with an adhesive. The area surrounded by the opposing separation membrane 1, the two side sealing sections 11, and the outer peripheral sealing section 12 is called the permeate side flow path, which is a structure that communicates with the opening 5a of the central tube 5.

[0054] Furthermore, in this invention, such as Figure 1B As shown, it may also have a central-side sealing portion 13 that seals the base ends of the perforated central tube 5 and the membrane leaf L with an adhesive. In this example, it has a wound body R formed by winding the membrane leaf L and the supply-side spacer 2 around the central tube 5 through such a central-side sealing portion 13. It should be noted that there is no particular limitation on the adhesive. For example, any conventionally known adhesive such as urethane adhesives or epoxy adhesives may be used.

[0055] In typical membrane element UEs, such as Figure 1A As shown, an upstream end component 10, such as a sealing bracket, is provided on the upstream side of the wound body R, and a downstream end component 20, such as an anti-stretching material, is provided on the downstream side. These upstream end components 10 and downstream end components 20 can also be integrated with the wound body R by winding FRP, which forms the outer casing material 15, around the outer periphery of the wound body R.

[0056] In a typical 8-inch diameter spiral membrane element, the membrane blades L are wound in approximately 15 to 30 sets. When using the membrane element UE, it is housed within a pressure vessel (container), and the supply fluid 7 is supplied from one end face of the membrane element UE.

[0057] like Figure 1A As shown, the supplied supply liquid 7 flows along the supply-side spacer 2 in a direction parallel to the axial direction A1 of the central tube 5, and is discharged as concentrate 9 from the other end face of the membrane element UE. In addition, during the flow of the supply liquid 7 along the supply-side spacer 2, the permeate 8 that permeates from the separation membrane 1 flows along the permeate-side spacer 3, flows into the interior of the central tube 5 through the opening 5a, and is discharged from the end of the central tube 5.

[0058] Typically, the supply-side spacer 2 serves to ensure sufficient clearance for fluid supply across the entire membrane surface. Such a supply-side spacer 2 can be made of materials such as mesh, woven fabric, or textured sheets, and a maximum thickness of approximately 0.1 to 3 mm can be used as needed. Furthermore, while spacers are provided on both sides of the separation membrane 1, different flow path materials are typically used for the supply-side spacer 2 on the supply liquid side and the permeate-side spacer 3 on the permeate side. For the supply-side spacer 2, a coarse and thick mesh flow path material is preferred; on the other hand, for the permeate-side spacer 3, a fine-mesh woven or knitted fabric flow path material is preferred.

[0059] like Figure 1A As shown, the central tube 5 can have an opening 5a around its perimeter, or any conventional tube can be used. Typically, in applications such as seawater desalination and wastewater treatment, the permeate water passing through the separation membrane 1 flows into the central tube 5 along the permeate-side flow path formed by the permeate-side spacer 3 sandwiched between opposing separation membranes 1, then flows into the central tube 5 through the opening 5a, flows within the central tube 5, and is discharged from the end.

[0060] Regarding the side spacer 3, in applications such as seawater desalination and wastewater treatment, when using RO membranes or NF membranes, such as Figure 1A As shown, the membrane leaf L is sandwiched between opposing separation membranes 1. This permeate-side spacer is required to withstand the pressure applied to the membrane from the back of the membrane and to ensure the flow path of the permeate.

[0061] To ensure such functionality, the permeable side spacer 3 is preferably formed from Trico warp-knitted fabric, and more preferably from Trico warp-knitted fabric that has undergone resin impregnation reinforcement or welding treatment after the knitting fabric is formed.

[0062] Various porous membranes can be used as the separation membrane 1, but a composite semi-permeable membrane with a separation functional layer on the surface of the porous support is preferred. As the porous support, a polymer porous layer is preferably present on one side of the nonwoven fabric layer.

[0063] Such composite semi-permeable membranes are called RO (reverse osmosis) membranes, NF (nanofiltration) membranes, and FO (forward osmosis) membranes depending on their filtration performance and treatment methods. They can be used for ultrapure water production, seawater desalination, desalination of alkaline water, and reuse of wastewater.

[0064] Various sheets, films, tapes, etc., can be used as the outer casing material 15, and fiber-reinforced resin (FRP) or the like can be used for reinforcement as needed. In a structure in which the upstream end component 10 and the downstream end component 20 are firmly integrated using the outer casing FRP, it is difficult to disassemble the membrane element UE, etc. However, in the present invention, disassembly is not performed, and the sealing portions 11 on both sides can be removed when they are cut off.

[0065] (The process of cutting off the sealing parts on both sides) Figure 2A This is a top view showing an example of the process of cutting off the sealing portions 11 on both sides. Figure 2B This is an unfolded view showing an example of the process of cutting off the sealing portions 11 on both sides, and it is a view showing one of the membrane leaves L unfolded.

[0066] For example, Figures 2A-2B As shown, the membrane element regeneration method of the present invention includes a step of cutting off at least two side sealing portions 11 of the used membrane element UE. Here, typically, the two side sealing portions 11 include opposing separation membranes 1 and a permeation-side spacer 3 sandwiched between them. Figure 2A As shown, in this process, when the sealing portions 11 on both sides are cut off, it is preferable to cut off the two ends on the axial direction A1 of the supply side spacer 2.

[0067] like Figure 3 As shown, through this process, only the outer peripheral sealing portion 12 of the sealing portion at the three ends of the membrane leaf L has the opposing separation membrane 1 and the permeate-side spacer 3 bonded together. At this time, one or more membrane leaves L1 may be fixed to the central tube 5 via the permeate-side spacer 3 (bonding, etc.). At this time, one or more inner peripheral ends of the permeate-side spacer 3 may be fixed to the central tube 5; furthermore, one or more inner peripheral ends of other permeate-side spacers 3 may also be fixed to the inner peripheral ends of the permeate-side spacers 3 fixed to the central tube 5. That is, all permeate-side spacers 3 may be directly or indirectly fixed to the central tube 5. It should be noted that when the two ends of the supply-side spacer 2 are cut off, the length of the supply-side spacer 2 in the axial direction A1 can be made consistent with the length of the permeate-side spacer 3.

[0068] In this process, at least the two sealing portions 11 can be cut from the main body of the membrane element UE, or the ends of the central tube 5, the upstream end component 10, or the downstream end component 20 can be cut off simultaneously. That is, the ends of the central tube 5 can be retained without cutting it off. It should be noted that in this embodiment, an example is shown where the two sealing portions 11, the two ends of the central tube 5, the upstream end component 10, and the downstream end component 20 are cut off.

[0069] Methods for removing the two-sided sealing portions 11 include, for example, cutting at the cutting line C1 to remove both ends of the winding body R, including the two-sided sealing portions 11, and both ends of the central tube 5 from the body of the membrane element UE; or cutting only the winding body R without cutting the central tube 5 to separate both ends of the winding body R, including the two-sided sealing portions 11, from the body of the membrane element UE. The upstream end member 10 and the downstream end member 20 may also be removed simultaneously or separately. It should be noted that methods such as cutting can also be used to remove both ends of the winding body R, including the two-sided sealing portions 11, as a whole.

[0070] Based on the length of the separation membrane 1 along the axial direction A1, the width of the sealing portions 11 on both sides of the used membrane element UE when cut off is preferably 50 mm or less. In addition, based on the length of the separation membrane 1 along the axial direction A1 before cutting off, the length of the separation membrane 1 after cutting off is preferably 87% or more of the length before cutting off.

[0071] (The process of cutting off the outer peripheral sealing portion) Figure 3 This is an unfolded view showing an example of the process of cutting off the outer peripheral sealing portion 12. It is a view showing one of the membrane leaf L1 with the sealing portions 11 on both sides cut off.

[0072] like Figure 3 As shown, the regeneration method of the membrane element of the present invention includes, for example, the steps of unfolding the cut membrane leaf L1 and cutting off at least the outer peripheral sealing portion 12 of the membrane leaf L1. In this embodiment, an example of cutting the outer peripheral sealing portion 12 from the cutting line C2 is shown. Here, the outer peripheral sealing portion 12 typically includes opposing separation membranes 1 and a permeation-side spacer 3 sandwiched between them. Furthermore, "unfolding the membrane leaf L1" means unfolding the wound membrane leaf L1 in a manner that facilitates cutting, and does not necessarily require the membrane leaf L1 to be planar.

[0073] like Figure 4B As shown, through this process, the sealing portions at the three ends of the membrane leaf L are removed, resulting in a membrane leaf L2 that can separate the opposing separation membrane 1 from the permeate-side spacer 3. This allows the separation membrane 1 to be replaced with a new separation membrane 1'. Furthermore, the removal of the supply-side spacer 2 becomes easier when or after unfolding the removed membrane leaf L1. Therefore, the supply-side spacer 2 can be replaced before or after the outer peripheral sealing portion 12 is removed.

[0074] In this process, at least the outer peripheral sealing portion 12 can be cut from the main body of the membrane element UE. Alternatively, other components such as adhesive tape present around the winding body R can be removed beforehand or simultaneously. Furthermore, the process of removing the outer casing material 15 can be performed after the sealing portions 11 on both sides are cut off. The process of removing the outer casing material 15 will be described later.

[0075] Based on the length of the separation membrane 1 perpendicular to the axial direction A1, the width of the outer peripheral sealing portion 12 of the used membrane element UE when it is cut off is preferably 50 mm or less. In addition, based on the length of the separation membrane 1 perpendicular to the axial direction A1 before cutting, the length of the separation membrane 1 after cutting is preferably 87% or more of the length before cutting.

[0076] In this way, based on the length of the separation membrane 1 in two directions before removal, by making the width of the side sealing portions 11 and the outer peripheral sealing portion 12 when they are removed both 87% or more of the width before removal, it is possible to make the effective membrane area of ​​the regenerated membrane element RE be more than 76% of the effective membrane area of ​​the used membrane element UE (87% × 87% = 76%).

[0077] (The procedure for replacing the separation membrane) Figure 4A This is an unfolded diagram showing an example of the process of replacing the membrane 1' with a new one. It is a diagram showing one of the membrane leaf L2 before replacement. Figure 4B The diagram shows one of the membrane leaf L2 being replaced unfolded, and the imaginary line continuous with the separation membrane 1 shows the state in which the separation membrane 1 is folded. Figure 5A This is a perspective view showing an example of the process of replacing the separation membrane 1' with a new one, showing the insertion of a new separation membrane 1' into a plurality of permeation-side spacers 3 and a supply-side spacer 2'. Figure 5B This is a perspective view showing an example of the process of replacing the separation membrane 1' with a new one, showing a state in which multiple new separation membranes 1' and supply-side spacers 2' are inserted into multiple permeation-side spacers 3.

[0078] For example, such as Figures 4A to 5B As shown, the membrane element regeneration method of the present invention includes the step of replacing at least the separation membrane 1 of the unfolded and cut membrane leaf L2 with a new separation membrane 1'. Figure 5B As shown, through this process, a component obtained by replacing the separation membrane 1 with a new separation membrane 1' can be obtained. At this time, at least the permeate-side spacer 3 is reused, but it is preferable to reuse the permeate-side spacer 3 and the central tube 5 if the degree of deterioration due to use is low. In this embodiment, an example of replacing the supply-side spacer 2 with a new supply-side spacer 2' is also shown, but depending on the degree of deterioration, the used supply-side spacer 2 can also be used directly, or it can be cleaned, repaired, etc. This will be described later.

[0079] like Figure 4BAs shown, when replacing the separation membrane 1, the separation membrane 1, which is disposed on both sides of the permeation-side spacer 3 and is in a folded state, is removed. Sometimes, one or more permeation-side spacers 3 are directly or indirectly bonded to the central tube 5 via other permeation-side spacers 3. In such cases, the separation membrane 1 can be removed to the outside of the central tube 5 (e.g., in the direction of the arrow). At this time, the supply-side spacer 2 (not shown) can be removed simultaneously with the folded separation membrane 1 or removed separately.

[0080] like Figure 5A As shown in this embodiment, an example is shown in which only one through-side spacer 3 is bonded to the central tube 5, but it is also possible to bond the inner circumferential ends of other through-side spacers 3 to the through-side spacer 3 in advance.

[0081] Next, as Figure 5A As shown, a new separation membrane 1' in a folded state and a supply-side spacer 2' are inserted between multiple permeable-side spacers 3. In cases where the multiple permeable-side spacers 3 are not bonded to each other, the components including the new separation membrane 1' in a folded state and the supply-side spacer 2' sandwiched therebetween can be alternately placed with the permeable-side spacers 3.

[0082] In the process of replacing the separation membrane 1' with a new one, it is preferable to provide an adhesive unit for forming the sealing portion. For example, in Figure 5B In the example shown, adhesives 4 and 6 are applied to the side of the separator 1' that is in contact with the permeation-side spacer 3 to form the sealing portion at the three ends. However, heat bonding can also be performed using a heat-bonding sheet or the like. Alternatively, adhesives 4 and 6 can be applied to the permeation-side spacer 3 instead of the separator 1'. It should be noted that the inner circumferential end of the supply-side spacer 2' can also be pre-fixed or temporarily fixed to the bend of the separator 1'.

[0083] (The process of replacing the supply-side spacers) Regarding the supply-side spacer 2, when the sealing portions 11 on both sides of the membrane leaf L are cut off, the ends on both sides of the supply-side spacer 2 can be cut off simultaneously, so that the length of the supply-side spacer 2 in the axial direction A1 is consistent with that of the through-side spacer 3. Therefore, the supply-side spacer 2 can be used directly.

[0084] Alternatively, the supply-side spacer 2 can be reused as a recycled supply-side spacer after the contaminants are removed by cleaning. Alternatively, it can be replaced with a new supply-side spacer.

[0085] The replacement of the supply-side spacer 2 can also be performed after replacing the separation membrane 1 with a new separation membrane 1', but from the viewpoint of simplifying the process, such as Figure 5A As shown, it is preferable to replace the supply-side spacer 2 when replacing the separation membrane 1 with a new separation membrane 1'.

[0086] (The procedure for replacing the central tube) Regarding the central tube 5, when the sealing portions 11 on both sides of the membrane leaf L are cut off, the ends on both sides of the central tube 5 can be cut off simultaneously, so that the length of the central tube 5 in the axial direction A1 of the through-side spacer 3 is consistent. Therefore, the central tube 5 can be used directly.

[0087] Alternatively, when cutting off the sealing portions 11 on both sides of the membrane leaf L, the ends of the central tube 5 may not be cut off simultaneously and may be retained, ultimately using a regeneration central tube cut to an appropriate length. Alternatively, a new central tube 5 may be used instead.

[0088] However, since the central tube 5 suffers minimal deterioration due to use, when cutting off the sealing portions 11 on both sides of the membrane leaf L, it is preferable to directly reuse the central tube 5, even after the ends on both sides have been cut off. Of course, if reuse is difficult due to the location of the opening 5a in the central tube 5, it is preferable to replace it with a new central tube 5.

[0089] (The process of obtaining regenerated membrane elements) Figure 6A This is a top view showing an example of cutting off the end of a regenerated membrane element with a sealing portion formed, showing the state before cutting. Figure 6B This is a top view showing an example of cutting off the end of a regenerated membrane element with a sealing portion formed, showing the state after cutting.

[0090] The membrane element regeneration method of the present invention includes a step of forming a two-sided sealing portion 11 and an outer peripheral sealing portion 12 to seal the two side ends and the outer peripheral end of the replaced membrane leaf in the axial direction A1, thereby obtaining a regenerated membrane element RE. Figure 6B As shown, through this process, a regenerated membrane element RE can be obtained in which at least separation membrane 1 is replaced with a new separation membrane 1'. Figures 6A-6B As shown in this embodiment, after forming a sealed portion with an adhesive or the like while the replaced membrane leaf is wound around the central tube 5, an example is shown where the end is trimmed after an external material is applied as needed.

[0091] First, at least replace the separation membrane 1 with a new separation membrane 1', and wind the laminate LB, which is provided with adhesive units for forming a sealing portion, onto the central tube 5. Figure 5B (The direction of the arrow). The laminate LB includes: a component formed from a new separation membrane 1' in a folded state and a supply-side spacer 2' sandwiched therebetween; and a permeation-side spacer 3, wherein the component formed from the separation membrane 1' and the supply-side spacer 2' is alternately laminated with the permeation-side spacer 3.

[0092] By curing the adhesive, etc., while the laminate LB is wound around the central tube 5, it is possible to obtain... Figure 6A The coiled body R shown before trimming has two side sealing portions 11' and an outer peripheral sealing portion 12.

[0093] Next, as Figure 6B As shown, the regenerated membrane element RE can be obtained by trimming both ends of the winding body R along the cutting line C3. Trimming is preferable to align the end faces of the regenerated membrane element RE. At this time, by also trimming the central tube 5, the length of the central tube 5 can be made the same as that of the winding body R.

[0094] New outer material 15 can be installed in the regenerated membrane element RE, and the length of the central tube 5 can be adjusted and an upstream end component 10 or a downstream end component 20 can be installed. The upstream end component 10 or the downstream end component 20 can be a new component or a component recovered from a used membrane element UE.

[0095] (The process of removing outer packaging materials) In this invention, it is preferable to remove the outer material 15 after cutting off the sealing portions 11 on both sides. This makes it easier to unfold the membrane leaf L1 with the sealing portions 11 on both sides removed and to cut off the outer peripheral sealing portion 12.

[0096] When the outer material 15 includes FRP, there are cases where the FRP is formed directly on the outer periphery of the winding body R, and other components are sandwiched between the FRP and the winding body R. In any case, removing the outer material 15 can be made easier by cutting the FRP at one or more points along the direction of the central tube 5. If other components are sandwiched between the FRP, removing the cut outer material 15 becomes even easier.

[0097] When FRP is directly bonded to the outer periphery of the wound body R, it can be removed by cutting or the like. During cutting, the outer peripheral sealing portion 12 located at the outermost periphery of the wound body R may sometimes be damaged, but in the present invention, since the outer peripheral sealing portion 12 is subsequently removed, this problem is less likely to occur.

[0098] (The effect of reducing CO2 emissions) In the membrane element regeneration method of the present invention, the CO2 emission reduction effect based on the reuse of raw materials is expected to be 16% or more. As a condition for calculation, the reuse rates of the permeate-side spacer, the central tube, and the supply-side spacer are set to 90%, 90%, and 50%, respectively. In addition, the reduction in CO2 emissions is calculated based on the raw materials and manufacturing processes under the conditions of using all new materials and using recycled materials.

[0099] (Other embodiments of the membrane element regeneration method) (1) The above embodiment shows an example in which the two side sealing portions 11, the two ends of the central tube 5, the upstream side end component 10 and the downstream side end component 20 are cut off during the process of cutting off the two side sealing portions 11, but as Figure 10 As shown, the two ends of the central tube 5 can also be retained while the two sealing portions 11, the upstream end component 10, and the downstream end component 20 are cut off. That is, the ends can also be retained without cutting off the central tube 5.

[0100] If the two ends of the central tube 5 are retained and the two sealing portions 11 are cut off, then... Figures 11A-11B As shown, the length of the central tube 5 is longer than the length of the membrane leaf L2 in the axial direction A1 before replacement. In this case, the two ends of the central tube 5 can be cut off after the process of obtaining the regenerated membrane element RE is completed or in the process before that. In this case, it is preferable to make the length of the central tube 5 the same as the length of the winding body R of the regenerated membrane element RE in the axial direction A1 or to make the two lengths closer.

[0101] (Membrane module) Figure 7A This is a cross-sectional view illustrating an example of the regenerated membrane element and interconnect used in the membrane assembly of the present invention. Figure 7B This is a cross-sectional view showing an example of the main parts of the membrane assembly of the present invention.

[0102] like Figures 7A-7B As shown, the membrane assembly of the present invention is characterized in that it is a membrane assembly comprising a membrane element and a container V for housing the membrane element, wherein the membrane element is a regenerated membrane element RE manufactured using a portion of a used membrane element UE, and the length of the regenerated membrane element RE in the axial direction A1 of the separation membrane 1 is shortened, and the container V houses one or more regenerated membrane elements RE than the number of used membrane elements UE.

[0103] This embodiment shows an example where the regenerated membrane elements RE are connected to each other by an interconnect 21 with an anti-stretch function. Here, the interconnect 21 can be a built-in type that fits into the inner circumference of the central tube 5 and an external type that fits into the outer circumference of the central tube 5, but this embodiment shows an example of the built-in type.

[0104] As container V, any container capable of accommodating a typical membrane element can be used. Container V may be the same as or different from the container that has housed the used membrane element UE.

[0105] As a regenerated membrane element RE, any regenerated membrane element manufactured using a portion of a used membrane element UE, wherein the length of the separation membrane 1 in the axial direction A1 has been shortened, is acceptable. Preferably, the regenerated membrane element RE obtained by the membrane element regeneration method of the present invention is preferred. In this embodiment, an example is shown where the length of the regenerated membrane element RE in the axial direction A1 of the separation membrane 1 is the same as the length of the central tube 5.

[0106] like Figures 7A-7B As shown, in this example, when the central tube 5 of the used membrane element UE has an enlarged inner circumference as the fitting portion 5b of the interconnect 21, the length of the fitting portion 5b becomes shorter in the regenerated membrane element RE.

[0107] Furthermore, the regenerated membrane element RE can be a membrane element in which the upstream end component 10 and the downstream end component 20 are integrally disposed, or it can be a membrane element in which the length of the central tube 5 is longer than the length of the separation membrane 1 in the axial direction A1. However, by using a regenerated membrane element RE of the same length as the separation membrane 1 and the central tube 5, it is easier to suppress the decrease in the total membrane area in the membrane module.

[0108] That is, although the effective membrane area of ​​each regenerated membrane element RE decreases due to regeneration, by connecting the regenerated membrane elements RE to each other with an interconnect 21 having an anti-stretch function, it is possible to house more than one regenerated membrane element RE than the number of used membrane elements UE in the container V, thereby increasing the overall effective membrane area of ​​the regenerated membrane elements RE.

[0109] like Figures 7A-7B As shown, the interconnect 21 includes a main body 22, a flow path forming part 23, and a sealing and holding part 24. The main body 22 has a groove for holding sealing members 25 such as O-rings. The two sides of the main body 22 are inserted into the fitting parts 5b on the inner circumferential side of the central tube 5 of the regenerated membrane element RE, and are kept sealed by the sealing members 25. When using an interconnect 21 with anti-stretch function, it can also be made into an external type, but from the viewpoint of simplifying the structure, an internal type interconnect 21 is preferred.

[0110] The flow path forming section 23 has an opening for ensuring the flow of the supply liquid 7, etc., and is formed by a plurality of plates arranged radially. The sealing and retaining section 24 is formed in an annular shape and has a groove on its outer periphery for retaining the sealing member 26 with a U-shaped cross section, etc. That is, the interconnector 21 has an anti-expansion function and an outer periphery sealing function.

[0111] In order to house more than one regenerated membrane element RE than the number of used membrane elements UE in the container V, the length of the regenerated membrane element RE in the axial direction A1, i.e. the length of the separation membrane 1' in the same direction, can be adjusted when manufacturing the regenerated membrane element RE.

[0112] For example, if the length of the used membrane element UE is 40 inches = 1016 mm and the number of elements is 6, as long as the length of the regenerated membrane element RE is 34 inches = 864 mm, the overall effective membrane area before and after replacing it with the regenerated membrane element RE can be maintained by storing 7 regenerated membrane elements RE in the same container V.

[0113] Furthermore, when manufacturing a regenerated membrane element RE whose length in the axial direction A1 of the separation membrane 1 is shortened, as described above, based on the length of the separation membrane 1 in two directions before removal, by ensuring that the width of the side sealing portions 11 and the outer peripheral sealing portions 12 when removed is at least 87% of the width before removal, the effective membrane area of ​​the resulting regenerated membrane element RE can be at least 76% of the effective membrane area of ​​the used membrane element UE (87% × 87% = 76%).

[0114] Therefore, in the membrane module of the present invention, the effective membrane area of ​​the regenerated membrane element RE is preferably 76% or more of the effective membrane area of ​​the used membrane element UE. Alternatively, the effective membrane area of ​​the regenerated membrane element RE can be made to be 80% or more of the effective membrane area of ​​the used membrane element UE by further reducing the width when the side sealing portions 11 or the outer peripheral sealing portions 12 are cut off.

[0115] (Other embodiments of membrane modules) (1) In this invention, instead of providing an interconnector 21 with anti-stretching function, for example, such as Figures 8A-8B As shown, the regenerated membrane elements RE can also be given an anti-stretching function, and the regenerated membrane elements RE can be connected to each other by an interconnector 21 of a generally structured structure that connects the central tubes 5 to each other. In this case, the interconnector 21 can be either built-in or external.

[0116] As a structure that imparts anti-stretching function to the regenerated membrane element RE, examples include structures formed by bonding the anti-stretching material 30 to the end of the central tube 5. In this case, the length of the central tube 5 can be the same as the length of the winding body R, but from the viewpoint of ensuring strength, for example... Figures 8A-8B As shown, the preferred structure is one in which the length of the central tube 5 is greater than the length of the winding body R, and the anti-stretch material 30 is bonded to the outer periphery of the extended portion.

[0117] In the illustrated example, the anti-stretch material 30 includes an annular portion 32, a flow path forming portion 33, and a sealing and retaining portion 34. The inner circumferential surface of the annular portion 32 is fixed to the end of the central tube 5. The flow path forming portion 33 has an opening for ensuring the flow of the supply liquid 7, etc., and is formed by a plurality of plates arranged radially. The sealing and retaining portion 34 is formed in an annular shape and has a groove on its outer periphery for retaining the sealing member 26 with a U-shaped or similar cross-section. That is, the anti-stretch material 30 has both anti-stretch function and outer peripheral sealing function.

[0118] In addition, regarding the interconnector 21, the main body 22 has a groove for holding the sealing member 25 such as the O-ring, and the two sides of the main body 22 are inserted into the fitting part 5b on the inner circumferential side of the central tube 5 of the regenerated membrane element RE, and are kept sealed by the sealing member 25.

[0119] (2) In this invention, instead of providing an interconnector 21 with anti-stretching function, for example, such as Figures 9A-9B As shown, the anti-stretch material 30 and the interconnector 21 can also be separate structures. In this case, the interconnector is inserted into the central opening of the anti-stretch material 30, but it is preferable to provide a locking part 27 in the interconnector 21 to prevent the anti-stretch material 30 from moving downstream.

[0120] (3) In this invention, it is preferable to provide an adjustment mechanism for maintaining the length on the upstream side of the upstream regenerated membrane element RE, in such a way that the multiple regenerated membrane elements RE connected by the interconnector 21 are housed as a whole and held in a predetermined position within the container V.

[0121] As an adjustment mechanism for maintaining length, examples include a special connector that can be connected to the container located on the upstream side and a connector that can be held at the upstream end of the container V. Additionally, examples include a ring-shaped component that is combined with such a connector and can be clamped between the upstream end of the container V and the connector, and an adjusting bolt located at the upstream end of the container V for pressing the connector to the central side.

[0122] Industrial availability According to the membrane element regeneration method of the present invention, at least the central tube and the permeate side spacer can be reused, thereby reducing waste caused by the used membrane element and reducing the amount of new plastic input in the manufacture of the regenerated membrane element, thus saving valuable petroleum resources.

[0123] According to the membrane assembly of the present invention, a regenerated membrane element that reuses at least the central tube and the permeate side spacer can be used while suppressing the overall membrane area decrease.

Claims

1. A membrane element regeneration method, which utilizes a portion of a used membrane element to manufacture a regenerated membrane element, wherein... The used membrane element comprises: a permeation-side spacer sandwiched between opposing separation membranes, and a plurality of membrane leaves having a two-sided sealing portion and an outer peripheral sealing portion that seal the two-sided ends and the outer peripheral ends in the axial direction; and a supply-side spacer sandwiched between the membrane leaves. and a perforated central tube wound with the membrane leaf and the supply-side spacer, The regeneration method includes: The process of cutting off at least the sealing portions on both sides of the used membrane element; The process of unfolding the removed membrane leaf and removing at least the outer peripheral sealing portion of the membrane leaf; The process of replacing at least the separation membrane of the unfolded and removed membrane leaf with a new separation membrane; and The process of forming a two-sided sealing part and an outer peripheral sealing part to seal the two sides and the outer peripheral side of the replaced membrane leaf in the axial direction, thereby obtaining a regenerated membrane element.

2. The method for regenerating a membrane element as described in claim 1, wherein, When replacing the new separation membrane, the supply-side spacer is replaced with a regenerated supply-side spacer that has been cleaned to remove contaminants, or with a new supply-side spacer.

3. The method for regenerating a membrane element as described in claim 1, wherein, The membrane element after use has an outer casing material, which is removed after the sealing portions on both sides are cut off.

4. The method for regenerating a membrane element as described in claim 1, wherein, The central tube of the membrane element after use is replaced with a regenerated central tube whose length has been adjusted by cutting, or it is replaced with a new central tube.

5. A membrane module, which comprises a membrane element and a container housing the membrane element, wherein, The membrane element is a regenerated membrane element manufactured using a portion of a used membrane element, wherein the length of the separation membrane in the axial direction has been shortened. The membrane module contains one or more regenerated membrane elements in the container than the number of used membrane elements.

6. The membrane module of claim 5, wherein, The regenerated membrane elements are connected to each other by interconnects with anti-stretching function, or the regenerated membrane elements with anti-stretching function are connected to each other by interconnects.

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