Cleaning method for seperation membrane and Seperation membrane cleaned with the same method

Abstract

The present invention relates to a separation membrane cleaning method, and more specifically, to a separation membrane cleaning method that introduces a bubble cleaning means, which is a physical cleaning method, and to an invention capable of providing a separation membrane that prevents discoloration and functional degradation of the separation membrane caused by unreacted compounds by minimizing the residual amount of unreacted compounds through cleaning treatment by this method.

Description

Technology Field

[0001] The present invention relates to a separation membrane cleaning method that improves cleaning efficiency by performing cleaning in a cleaning tank equipped with a bubble generator during the cleaning process for removing unreacted materials after polyamide interfacial polymerization in the manufacture of a separation membrane, and to a separation membrane manufactured by this method. Background Technology

[0003] Osmosis refers to the phenomenon in which a solvent moves through a membrane between two solutions separated by a semipermeable membrane, from a solution with a lower solute concentration to a solution with a higher solute concentration. The pressure exerted on the side of the solution with the higher solute concentration due to this movement of the solvent is called osmotic pressure. Conversely, if an external pressure higher than the osmotic pressure is applied, the solvent moves toward the solution with the lower solute concentration; this phenomenon is called reverse osmosis.

[0004] Conventional applications of reverse osmosis membranes are desalination processes for brackish water or seawater, and such desalination processes provide large quantities of fresh or pure water that is relatively suitable for industrial, agricultural, or domestic use. The desalination process of brackish water or seawater using reverse osmosis membranes is a process that literally filters out salts and other dissolved ions or molecules from brine. By passing brine through a reverse osmosis membrane and pressurizing it, purified water passes through the membrane, while salts and other dissolved ions or molecules do not pass through the membrane.

[0005] Polyamide-based reverse osmosis membranes essentially comprise a porous support layer and a polyamide layer, wherein the polyamide layer is formed by interfacial polymerization of polyamide resin. However, if unreacted compounds (MPD, TOC, etc.) remain after interfacial polymerization, their oxidation causes problems such as discoloration of the membrane and degradation of membrane performance; therefore, after the interfacial polymerization reaction, a cleaning process is performed to remove unreacted compounds and / or solvents, and to increase cleaning efficiency, the temperature of the cleaning tank is raised during the process. Prior art literature

[0007] Korean Published Patent No. 10-2015-0087579 (Publication Date: July 30, 2015) Japanese Published Patent No. JP 2006-263501 (Publication Date: October 5, 2006) The problem to be solved

[0008] The present invention aims to provide a cleaning method that introduces a bubble cleaning means, which is a physical means, to remove residual unreacted compounds after polyamide interfacial polymerization during the manufacture of a separation membrane. means of solving the problem

[0010] To solve the above-mentioned problem, the present invention relates to a membrane cleaning method, wherein the membrane cleaning method is performed using a membrane cleaning system comprising: a bubble cleaning tank; a front cleaning tank and a bubble cleaning tank; or a front cleaning tank, a bubble cleaning tank and a rear cleaning tank, wherein the membrane is introduced into and flowed through the cleaning system to perform cleaning of the membrane.

[0011] As a preferred embodiment of the present invention, the shear cleaning tank, the bubble cleaning tank, and the downstream cleaning tank are each independently supplied with a cleaning solution containing a basic aqueous solution or water.

[0012] As a preferred embodiment of the present invention, the bubble cleaning tank is equipped with at least three rolls and at least one air bubble bar, the separator membrane is movable by the three rolls, and the air bubble bar supplies bubbles to at least one surface of the membrane passing through the bubble cleaning tank.

[0013] As a preferred embodiment of the present invention, the diameter of the bubble generated in the air bubble bar may be a microbubble of 5 to 50 μm.

[0014] As a preferred embodiment of the present invention, the amount of bubbles generated in the air bubble bar and introduced into the cleaning liquid may be 1.0 to 5.0 m³ / hr per air bubble bar.

[0015] In a preferred embodiment of the present invention, the rolls are spaced apart and arranged in an alternating manner, with an inner roll that transports the film inside the bubble cleaning tank and an outer roll that transports the film outside the bubble cleaning tank, and the air bubble bar may be spaced apart and arranged above the inner roll.

[0016] As a preferred embodiment of the present invention, 2 to 4 inner rolls are arranged, and The above-mentioned external rolls may be arranged in one or more greater numbers than the internal rolls.

[0017] As a preferred embodiment of the present invention, an air knife may be disposed between the last inner roll and the last outer roll through which the flowing membrane passes, and between the cleaning liquid surface and the last outer roll.

[0018] As a preferred embodiment of the present invention, the flow velocity of the separation membrane may be 10.0 to 22.0 m / min.

[0019] As a preferred embodiment of the present invention, the basic aqueous solution may comprise 0.1 to 1.0 weight% of a basic compound and the remaining amount of water among 100 weight%.

[0020] As a preferred embodiment of the present invention, the basic compound may include one or more compounds selected from soda ash, sodium bicarbonate, and sodium hydroxide.

[0021] As a preferred embodiment of the present invention, the separator comprises a porous support layer and a polyamide layer, and the one side to which bubbles are supplied may be a polyamide layer formed by performing polyamide interfacial polymerization.

[0022] As a preferred embodiment of the present invention, the separation membrane may be a reverse osmosis separation membrane.

[0023] Another objective of the present invention is to provide a separation membrane that has been cleaned using the cleaning method described above. Effects of the invention

[0025] The cleaning method of the present invention can efficiently remove residual unreacted material after a polyamide interfacial polymerization reaction for forming a polyamide layer, which is the active layer of a separation membrane, and the cleaning-treated separation membrane can have improved long-term performance stability and minimize discoloration. Brief explanation of the drawing

[0027] FIG. 1 is a schematic side view of a bubble cleaning tank in which a cleaning process is performed, as an embodiment of the cleaning method of the present invention. FIG. 2 is a schematic side view of a cleaning system composed of a front cleaning tank, a bubble cleaning tank, and a rear cleaning tank in which a cleaning process is performed, as an embodiment of the cleaning method of the present invention. Figure 3 shows a schematic side view illustrating the principle of a bubble cleaning system. Specific details for implementing the invention

[0028] Hereinafter, embodiments of the present invention are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. The present invention may be embodied in various different forms and is not limited to the embodiments described herein. In the drawings, parts unrelated to the explanation have been omitted to clearly explain the present invention, and the same reference numerals are assigned to identical or similar components throughout the specification.

[0030] The separation membrane cleaning method of the present invention is an invention that introduces a bubble cleaning method as a physical cleaning means and optimizes optimal cleaning conditions for bubble cleaning in order to efficiently remove residual unreacted compounds (e.g., diamines such as m-phenylenediamine and hexamethylenediamine, TOC (Total Organic Carbon)) after the interfacial polymerization reaction of a polyamide resin for forming a polyamide layer which is an active layer.

[0031] The separation membrane cleaning method of the present invention is a separation membrane cleaning method using a separation membrane cleaning system, wherein a separation membrane comprising a polyamide layer formed by performing an interfacial polymerization reaction of a polyamide resin is introduced and flowed into a cleaning tank into which a cleaning solution is introduced to clean the separation membrane.

[0032] The above cleaning system may be composed of a bubble cleaning tank alone, or composed of a front cleaning tank and a bubble cleaning tank, or composed of a front cleaning tank, a bubble cleaning tank and a rear cleaning tank, or composed of a bubble cleaning tank and a rear cleaning tank.

[0033] As a preferred embodiment, a schematic side view of the bubble cleaning tank is shown in FIG. 1, and a schematic side view of a cleaning system composed of a front cleaning tank, a bubble cleaning tank, and a rear cleaning tank is shown in FIG. 2. However, FIG. 1 and FIG. 2 are for illustrative purposes only and should not be interpreted as limiting the cleaning system applied to the cleaning method of the present invention to FIG. 1 and FIG. 2.

[0034] The bubble cleaning tank is equipped with at least three rollers and at least one air bubble bar, the separator membrane is movable by the three rollers, and the air bubble bar supplies bubbles to at least one side of the membrane passing through the cleaning tank.

[0035] Then, the separation membrane is introduced into and flowed in the cleaning solution so that the one side to which the bubble is supplied becomes a polyamide layer formed by performing polyamide interfacial polymerization.

[0036] The above roll may be composed of 2 to 4 inner rolls and one or more outer rolls arranged than the inner rolls.

[0037] Figure 1 shows a schematic side view of a cleaning process, which is a preferred embodiment, wherein the rolls (1, 2, 3, 4, 5, 6, 7) are spaced apart and arranged in an alternating manner, with an inner roll (2, 4, 6) that transports the film inside the cleaning tank and an outer roll (1, 3, 5, 7) that transports the film outside the cleaning tank, and the air bubble bar (30, 30', 30") is spaced apart and arranged above the inner roll.

[0038] Additionally, air knives (50, 50') may be positioned between the last inner roll (6) and the last outer roll (7) through which the flowing membrane passes, and between the surface of the cleaning liquid (100) and the last outer roll (7). At this time, the air knives are installed to remove the cleaning liquid from the inside and outside of the membrane, and it is appropriate to position them on each side of the membrane for effective removal of the cleaning liquid.

[0039] The diameter of the bubbles generated in the air bubble bar (30, 30', 30") may be microbubbles with a diameter of 5 to 50 μm, and preferably microbubbles with a diameter of 10 to 40 μm. At this time, if the diameter of the bubble is 5 μm or less, a high operating pressure is required, which may be uneconomical, and if it exceeds 50 μm, there may be a problem of reduced cleaning power. Therefore, it is advantageous in terms of cleaning effect to perform cleaning by installing an air bubble bar that forms bubbles of the above range.

[0040] In addition, the amount of bubbles generated in the air bubble bar (30, 30', 30") and introduced into the cleaning solution may be 1.0 to 5.0 m³ / hr per air bubble bar, preferably 1.8 to 4.2 m³ / hr per air bubble bar, and more preferably 2.0 to 4.0 m³ / hr per air bubble bar. At this time, if the amount of bubbles is less than 1.0 m³ / hr per air bubble bar, the cleaning effect may be insufficient, and even if it exceeds 5.0 m³ / hr, it is uneconomical because there is no additional increase in cleaning effect.

[0041] In addition, when the depth from the cleaning liquid surface to the center of the inner roll is defined as 1, it is advantageous in terms of efficient cleaning to position the air bubble bar at a depth of 0.90 to 0.95 from the cleaning liquid surface.

[0042] In addition, the flow rate of the membrane (i.e., the speed of the membrane passing through the cleaning solution) may be 10.0 to 22.0 m / min, preferably 15.0 to 20.0 m / min. At this time, if the flow rate of the membrane is less than 10.0 m / min, the cleaning time becomes too long, which is disadvantageous in terms of productivity, and if it exceeds 22.0 m / min, the cleaning efficiency may decrease. Therefore, it is appropriate to adjust the rotation speed of the roll so that the membrane flows within the above flow rate range.

[0043] The cleaning solution (100) of the cleaning tank may include a basic aqueous solution or water.

[0044] The above basic aqueous solution may comprise 0.1 to 1.0 wt% of a basic compound and the remaining amount of water in 100 wt%, preferably 0.15 to 0.40 wt% of a basic compound and the remaining amount of water in 100 wt%, and more preferably 0.18 to 0.35 wt% of a basic compound and the remaining amount of water in 100 wt%. In this case, using the basic compound within the above range is advantageous in terms of stably treating process wastewater while increasing the cleaning effect along with physical cleaning.

[0045] In addition, the basic compound may include one or more selected from soda ash, sodium bicarbonate, and sodium hydroxide.

[0046] The above separation membrane may be a reverse osmosis separation membrane comprising a porous support layer and a polyamide layer, and may further include a polymer support layer between the porous support layer and the polyamide layer.

[0047] The porous support layer is composed of a general porous support used in the manufacture of separation membranes, and, as a preferred example, may be a nonwoven fabric or woven fabric formed from synthetic fibers or natural fibers. Furthermore, as a preferred example of the synthetic fiber, it may include one or more selected from polyester fibers, polypropylene fibers, nylon fibers, and polyethylene fibers, and as a preferred example of the natural fiber, it may include cellulose-based fibers.

[0048] In addition, the polymer support layer is a layer formed from a polymer solution comprising a polymer compound and a solvent, wherein the polymer compound may include one or more selected from polysulfone-based polymers, polyethersulfone-based polymers, polyamide-based polymers, polyimide-based polymers, polyester-based polymers, olefin-based polymers, polyvinylidene fluoride, and polyacrylonitrile, and preferably may include a polysulfone-based polymer.

[0049] In addition, the above solvent may be used without particular limitation as long as it can uniformly and completely dissolve the polymer without precipitation, and preferably may include one or more selected from N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and dimethylacetamide (DMAc).

[0050] In addition, the polyamide layer is a layer formed by sequentially applying an amine solution and a polyfunctional acid halogen solution to the upper surface of a porous support layer or a polymer support layer and performing an interfacial polymerization reaction. The coating of the amine solution can be performed by spraying or immersing the amine solution onto the porous support on which the polymer support layer is formed, and can be performed for 0.1 to 10 minutes, preferably 0.5 to 1 minute. At this time, the amine solution may include an amine compound and a remainder of solvent, and the amine compound may be included in an amount of 0.1 to 20.0 weight% of the total weight of the amine solution, preferably 0.1 to 8.0 weight%, and more preferably 0.1 to 5.0 weight%.

[0051] In addition, the above amine compound is a substance having 1 to 3 amine functional groups per monomer, and may include one or more selected from a polyamine comprising a primary amine or a secondary amine; an aromatic primary diamine; an aliphatic primary diamine; a cycloaliphatic primary diamine; a cycloaliphatic secondary amine; and an aromatic secondary amine as a substituent, and preferably may include one or more selected from diamines metaphenylenediamine, paraphenylenediamine, orthophenylenediamine, cyclohexendiamine, and piperazine, more preferably may include one or more selected from metaphenylenediamine, paraphenylenediamine, and orthophenylenediamine, and even more preferably may include metaphenylenediamine (m-phenylenediamine).

[0052] In addition, the solvent of the amine solution may be used without particular limitation as long as it can uniformly dissolve the amine compound, and preferably may include water. The polyfunctional acid halogen solution may include a polyfunctional acid halogen compound and a remainder of solvent, and may include the polyfunctional acid halogen compound in an amount of 0.005 to 5.0 weight% of the total weight of the solution, preferably 0.01 to 2.0 weight%, and more preferably 0.05 to 1.00 weight%.

[0053] The above-mentioned polyfunctional acid halogen compound may include one or more selected from polyfunctional acyl halides, polyfunctional sulfonyl halides, and polyfunctional isocyanates, preferably may include trimesoyl chloride, isophthaloyl chloride, terephthaloyl chloride, 1,3,5-cyclohexane tricarbonyl chloride, and 1,2,3,4-cyclohexane tetracarbonyl chloride, and more preferably may include trimesoyl chloride (TMC).

[0054] In addition, the solvent of the polyfunctional acid halogen solution should be a solvent that does not mix with water, does not participate in interfacial polymerization reactions, does not chemically bond with the polyfunctional acid halogen compound, and does not damage the support, and it is preferable to use a mixture of structural isomers of n-alkanes having 5 to 12 carbon atoms and saturated or unsaturated hydrocarbons having 5 to 12 carbon atoms, or to use cyclic hydrocarbons having 5 to 7 carbon atoms.

[0056] Although the present invention has been described above with reference to embodiments, this is merely illustrative and does not limit the embodiments of the present invention. Those skilled in the art will understand that various modifications and applications not exemplified above are possible within the scope of the essential characteristics of the present invention. For example, each component specifically shown in the embodiments of the present invention may be modified and implemented. Furthermore, differences related to such modifications and applications should be interpreted as being included within the scope of the present invention as defined in the appended claims.

[0057] [Example]

[0058] Example 1: Preparation and cleaning treatment of a reverse osmosis membrane with an interfacially polymerized polyamide layer

[0059] (1) Preparation of reverse osmosis membrane

[0060] A porous polysulfone support with a thickness of 120 μm, including a polyethylene terephthalate (PET) nonwoven fabric, was prepared.

[0061] Next, a polymer solution containing 17.0 wt% of a polysulfone-based polymer (polymer compound) and the remainder of dimethylformamide (DMF) was applied and dried on the surface of the porous polysulfone support to form a polymer support layer on the surface of the porous polysulfone support.

[0062] Next, the porous support having the polymer support layer formed thereon was coated by immersing it in an aqueous solution containing 2.5 wt% of metaphenylenediamine (m-phenylenediamine, MPD) for 40 seconds, and then the excess aqueous solution was removed.

[0063] Next, a reverse osmosis membrane was prepared by immersing for 60 seconds in a polyfunctional acid halogen solution containing 0.1 wt% of trimesoyl chloride (TMC), a polyfunctional acid halogen compound, and the remainder in an isopar solvent, and then drying in air for 1 minute to form a polyamide layer, thereby forming a porous support layer, a polymer support layer, and a polyamide layer in sequence.

[0064] (2) Bubble cleaning treatment

[0065] As shown in the schematic diagram in Fig. 2, the reverse osmosis membrane was cleaned using a cleaning system composed of a front cleaning tank, a bubble cleaning tank, and a rear cleaning tank. The reverse osmosis membrane manufactured above was introduced into a front cleaning tank containing a cleaning solution and passed through the front cleaning tank, the bubble cleaning tank, and the rear cleaning tank to perform the cleaning treatment.

[0066] As shown in FIG. 1, the bubble cleaning tank is composed of seven rolls (four outer rolls and three inner rolls), and the reverse osmosis membrane is moved by the rolls, and an air bubble bar (30, 30', 30") is installed on the upper part of each of the three inner rolls. At this time, each of the three inner rolls is positioned at a depth of about 1.4 m from the surface of the cleaning liquid, and the air bubble bar is positioned at a depth of about 1.3 m from the surface of the cleaning liquid.

[0067] In addition, the above-mentioned front and rear cleaning tanks are configured with the same outer roll (7) and inner roll (6) as the bubble cleaning tank, except that an air bubble bar is not installed.

[0068] In addition, in each of the front cleaning tank, bubble cleaning tank, and rear cleaning tank, an air knife is installed on each side of the reverse osmosis membrane to remove the cleaning agent from the inside and outside of the reverse osmosis membrane before the reverse osmosis membrane passes through the last inner roll (6) and the last outer roll (7).

[0069] When introducing the reverse osmosis membrane into the bubble cleaning tank, it was introduced and flowed so that the polyamide layer faced upward in the cleaning tank, allowing the bubbles generated from the air bubble bar in the cleaning solution to come into direct contact with the polyamide layer.

[0070] In addition, the flow velocity of the reverse osmosis membrane was 18.0 m / min, and the amount of bubbles introduced into the cleaning solution in the bubble cleaning tank was approximately 3.0 m³ / hr per air bubble bar, and cleaning was performed by adjusting the conditions of the air bubble bar so that the diameter of the generated bubbles was 10 to 40 µm.

[0071] In addition, the cleaning solution introduced into the shear cleaning tank, bubble cleaning tank, and downstream cleaning tank used a basic aqueous solution containing 0.2% by weight of soda ash, a basic compound, and the remaining amount of water.

[0073] Comparative Example 1

[0074] Cleaning was performed using the same cleaning system as in Example 1, but without operating the air bubble bar, and the same reverse osmosis membrane as in Example 1 was cleaned under the same conditions.

[0076] Experimental Example 1: Measurement of Cleaning Effect

[0077] In order to confirm the cleaning effect performed in Example 1 and Comparative Example 1 above, flat film samples were obtained according to the location of the cleaning tank, and 10 cm x 10 cm (width, length) flat film samples were immersed in water (Pure water). After leaching for 1 day, the concentrations of TOC (Total Organic Carbon) and MPD (m-phenylenediamine) in the leached water were measured, and the results are shown in Table 1 below.

[0078] division Sample details TOC concentration (ppm) MPD concentration (ppm) Example 1 Bubble device shear cleaning tank 36.4 35.1 Cleaning tank with bubble device installed 20.8 21.22 Cleaning tank at the rear of the bubble device 7.82 7.14 Comparative Example 1 Bubble device shear cleaning tank 37.8 35.0 Cleaning tank with bubble device installed 23.5 26.11 Cleaning tank at the rear of the bubble device 9.57 12.34 control group water - -

[0080] Looking at the experimental results in Table 1 above, it was confirmed that the leaching concentration of organic matter containing MPD (m-Phenylene diamine), a major raw material for polyamide interfacial polymerization, was reduced as a result of the reverse osmosis membrane manufacturing process through bubble cleaning using an air bubble bar.

[0082] Examples 2 to 6 and Comparative Examples 2 to 6

[0083] Examples 2 to 6 and Comparative Examples 2 to 6 were carried out, respectively, by performing cleaning using the same cleaning system as in Example 1, but with different air bubble bar conditions as shown in Table 2 below, and by cleaning the same reverse osmosis membrane as in Example 1.

[0085] Experimental Example 2: Measurement of Cleaning Effect

[0086] The cleaning effect was measured in the same manner as in Experimental Example 1 above, but after obtaining flat membrane samples of Examples 2 to 6 and Comparative Examples 2 to 6 after the downstream cleaning tank was completed, a 10 cm x 10 cm (width, length) flat membrane sample was immersed in water (Pure water), and after elution for 1 day, the concentrations of TOC (Total Organic Carbon) and MPD (m-phenylenediamine) in the elution water were measured, and the results are shown in Table 2 below.

[0087] division Bubble volume per air bubble bar (㎥ / hr) Bubble diameter (㎛) Membrane flow velocity (m / min) Concentration of alkali-resistant compounds in cleaning solution (weight%) Air bubble bar position (relative to cleaning solution surface, m) TOC concentration (ppm) after downstream washing MPD concentration (ppm) after downstream cleaning Example 1 3.0 10 ~ 40 18.0 0.2 1.3 7.82 7.32 Example 2 1.8 10 ~ 40 18.0 0.2 1.3 9.78 8.17 Example 3 4.2 10 ~ 40 18.0 0.2 1.3 6.88 4.24 Example 4 3.0 20 ~ 50 18.0 0.2 1.3 8.45 8.32 Example 5 3.0 10 ~ 40 20.0 0.2 1.3 8.69 6.38 Example 6 3.0 10 ~ 40 18.0 1.0 1.3 7.74 6.17 Comparative Example 2 0.8 10 ~ 40 18.0 0.2 1.3 11.17 9.30 Comparative Example 3 5.2 10 ~ 40 18.0 0.2 1.3 6.89 4.22 Comparative Example 4 3.0 40 ~ 70 18.0 0.2 1.3 11.63 9.93 Comparative Example 5 3.0 10 ~ 40 23.0 0.2 1.3 9.99 9.02 Comparative Example 6 3.0 10 ~ 40 18.0 1.5 1.3 7.55 6.03 Comparative Example 7 3.0 10 ~ 40 18.0 0.2 1.1 7.99 7.72

[0088] Looking at the experimental results in Table 2 above, it was confirmed that Examples 1 to 6 had an overall excellent cleaning effect, and the cleaning effect increased as the amount of bubbles per air bubble bar increased and when the bubble diameter was smaller.

[0089] However, in the case of Comparative Example 2, where the amount of bubbles per air bubble bar was less than 1.0 m³ / hr, the cleaning effect was significantly reduced compared to Example 1 and Example 2, and in the case of Comparative Example 3, where the amount of bubbles per air bubble bar exceeded 5.0 m³ / hr, the cleaning effect was not increased compared to Example 3.

[0090] In addition, in the case of Comparative Example 4, in which cleaning was performed with a significantly increased diameter, the cleaning effect tended to decrease compared to Examples 1 and 5.

[0091] In addition, in the case of Comparative Example 5, where the flow rate of the membrane exceeded 22.0 m / min, the cleaning effect was relatively reduced compared to Example 1 and Example 5, and in particular, the MPD concentration showed a tendency to increase.

[0092] In addition, in the case of Comparative Example 6, where the concentration of the basic compound in the cleaning solution exceeded 1.0 wt%, the increase in cleaning effect was insufficient compared to Example 6.

[0093] In addition, in the case of Comparative Example 7, where the air bubble bar position was 1.1m relative to the surface of the cleaning liquid, there was no significant difference in terms of cleaning effect compared to Example 1, but a slightly lower cleaning effect was observed.

[0095] Simple variations or modifications of the present invention can be easily implemented by those skilled in the art, and all such variations or modifications are considered to be included within the scope of the present invention. Explanation of the symbols

[0097] 1,2,3,4,5,6,7 : Roll 1, 3, 5, 7: External rolls 2, 4, 6: Internal rolls 10 : Separator 30, 30', 30" : Air bubble bar 50, 50' : Air knife 100 : Cleaning solution

Claims

Claim 1 A method for cleaning a membrane using a membrane cleaning system comprising: a bubble cleaning tank; a front cleaning tank and a bubble cleaning tank; or a front cleaning tank, a bubble cleaning tank and a rear cleaning tank; wherein each of the front cleaning tank, the bubble cleaning tank, and the rear cleaning tank is independently supplied with a cleaning solution containing a basic aqueous solution or water, and a membrane is introduced into and flowed through the cleaning system to clean the membrane, wherein the bubble cleaning tank is equipped with at least three rolls and at least one air bubble bar, the membrane is flowed by the three rolls, and the air bubble bar supplies bubbles to at least one surface of the membrane passing through the bubble cleaning tank. Claim 2 A separation membrane cleaning method according to claim 1, characterized in that the diameter of the bubbles generated in the air bubble bar is 5 to 50 μm and is a microbubble. Claim 3 A membrane cleaning method according to claim 1, characterized in that the amount of bubbles generated in the air bubble bar and introduced into the cleaning solution is 1.0 to 5.0 m³ / hr per air bubble bar. Claim 4 A membrane cleaning method according to claim 1, characterized in that the rolls are spaced apart and arranged in an alternating manner, with an inner roll for transporting the membrane inside the bubble cleaning tank and an outer roll for transporting the membrane outside the bubble cleaning tank, and the air bubble bar is spaced apart and arranged above the inner roll. Claim 5 A membrane cleaning method according to claim 4, wherein 2 to 4 inner rolls are arranged, and at least one more outer roll is arranged than the inner rolls, and an air knife is arranged between the last inner roll and the last outer roll through which the flowing membrane passes, and between the cleaning liquid surface and the last outer roll. Claim 6 A membrane cleaning method according to claim 1, characterized in that the flow velocity of the membrane is 10 to 22 m / min. Claim 7 A separation membrane cleaning method according to claim 1, wherein the basic aqueous solution comprises 0.1 to 1.0 weight% of a basic compound and the remaining amount of water among 100 weight%, and the basic compound comprises one or more selected from soda ash, sodium bicarbonate, and sodium hydroxide. Claim 8 A separation membrane cleaning method according to claim 1, wherein the separation membrane comprises a porous support layer and a polyamide layer, and one side is a polyamide layer formed by performing polyamide interfacial polymerization. Claim 9 A method for cleaning a membrane, characterized in that, in any one of claims 1 to 8, the membrane is a reverse osmosis membrane. Claim 10 A separation membrane characterized by being cleaned using the cleaning method of claim 8.

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