JP2008246448A - Method for improving prevention rate of permeable membrane, blocking rate improved permeable membrane, method and device for treating permeable membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method for improving the blocking rate of a permeable membrane that increases the improvement effect of a blocking rate in a permeable membrane with a blocking rate improver, can maintain a high status of blocking rate improvement effect, and can perform a stable treatment for a long time since organic substance removal effect is high because of this, a method for treating a permeable membrane using the blocking rate improved permeable membrane, and a permeable membrane device suitable for these methods. <P>SOLUTION: The blocking rate improver 15 to which an electrolyte 18 is added is fed to the primary side 3 of a permeable membrane module 1 so as to allow a concentration to be 1,000 to 10,000 mg/L, after the blocking rate of the membrane 2 is improved by attaching the blocking rate improver to the membrane 2, a first fixing agent 16 containing a macromolecule with higher weight average molecular weight than that of the blocking rate improver is fed and is attached to a permeable membrane on which blocking rate improver treatment is performed, fixing agent treatment where a second fixing agent 17 containing an ionic macromolecule different from the first fixing agent is fed and attached is alternately performed once or more to maintain blocking rate improver treatment effect. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a method for improving the blocking rate of a permeable membrane such as a reverse osmosis membrane or a nanofiltration membrane, a permeable membrane with an improved blocking rate obtained thereby, a permeable membrane treatment method using the same, and a method suitable for these The present invention relates to a permeable membrane device.

  Permeation membranes used in water treatment, especially selective permeation membranes such as nanofiltration membranes and reverse osmosis membranes (RO membranes), have a blocking rate against separation objects such as inorganic electrolytes and water-soluble organic substances. It deteriorates due to deterioration of the raw material polymer due to the influence of reducing substances and other causes, and the required treated water quality cannot be obtained. This change may occur little by little during long-term use, or it may happen suddenly due to an accident. A method has been proposed in which the rejection rate of a permeable membrane with such a decreased rejection rate is improved by a rejection rate improver to restore performance.

  In general, an ultrapure water production system for producing high-purity pure water includes a reverse osmosis membrane treatment device and an electric regenerative deionization device or other ion-exchange device for advanced treatment of the permeated water of the reverse osmosis membrane treatment device. The device is built in. On the other hand, it has become possible to create a circuit having a line width of 65 nm or less due to recent progress in semiconductor circuit formation technology. Accordingly, the required water quality for ultrapure water is also increasing, and it is desired to develop a pure water production apparatus and a pure water production method that can reduce the load of post-treatment and realize pure water production at a higher level. There is a particular concern about the effects of organic components on the device, and water that eliminates this as much as possible is required.

  In such an ultrapure water production system, it has been proposed to treat a reverse osmosis membrane with a blocking rate improver (for example, Patent Document 1). Although patent document 1 is unpublished, a reverse osmosis membrane is processed with the blocking rate improver containing the polyalkylene glycol of the weight average molecular weight 2000-6000, or the ionic polymer which introduce | transduced the anionic functional group into it. It has been shown.

Patent Document 2 discloses hydrolyzable tannic acid, styrene / maleamic acid copolymer, C _{5 to} C ₇ hydroxyalkyl as a blocking rate improver for improving the blocking rate of a polyamide membrane in a method for producing a water softening membrane. A methacrylate polymer, copolymer or terpolymer, a coacervate made from a first polymer having a plurality of sulfonium or quaternary ammonium groups and a second polymer having a plurality of carboxylate groups, branches with any other substituents Fractionated polyamidoamines, vinyl acetate copolymers, copolymers of hydroxyethyl methacrylate and methacrylic acid or methacrylamide (optionally including other miscible monomers), styrene / maleamic acid copolymers, etc. are shown.

  Patent Document 3 discloses a blocking rate improver containing an ionic polymer having a weight average molecular weight of 100,000 or more as a blocking rate improver for improving the blocking rate of a permeable membrane used for water treatment. . Such ionic polymers include polyvinylamidine or derivatives thereof, cationic polymers such as cationic polymers having a heterocyclic ring, and anionic polymers such as polyacrylic acid or derivatives thereof, polystyrene sulfonic acid or derivatives thereof, and the like. The molecule is shown. Moreover, when improving a rejection rate using a rejection rate improvement agent, it is supposed that 100-1000 mg / L of inorganic electrolyte can be added as a monitor substance, but the example of 500 mg / L addition is shown in the Example.

The conventional process for improving the blocking rate of the permeable membrane is performed by supplying the above blocking rate improver and bringing it into contact with the permeable membrane in a state before the permeable membrane is attached or in a state where the permeable membrane is attached to the module. The blocking rate of the permeable membrane is improved by applying a modification treatment by attaching or reacting the entire or a part of the blocking rate improving agent to the structural material on the surface or inside of the membrane.
Japanese Patent Application No. 2006-218471 Japanese Patent No. 2762358 JP 2006-110520 A

  In the conventional treatment for improving the rejection rate of the permeable membrane, the effect of improving the rejection rate is low, and when the water to be treated is passed through after the modification treatment with the rejection rate improving agent is completed, a part of the modified polymer is desorbed. Then, the blocking rate improvement effect is lower than at the end of the modification treatment, and if the water to be treated is subsequently passed, the blocking rate improvement effect gradually decreases, and the blocking rate improvement effect cannot be maintained over a long period of time. There was a problem.

  In order to solve the above-mentioned conventional problems, the problem of the present invention is to increase the effect of improving the rejection rate of the permeable membrane by the rejection rate improver and to maintain the effect of improving the rejection rate in a high state. PROBLEM TO BE SOLVED: To provide a method for improving the rejection rate of a permeable membrane having a high organic substance removing effect and capable of stable treatment over a long period of time, a permeable membrane treatment method using a permeable membrane with an improved rejection rate, and a permeable membrane device suitable for them. It is.

The present invention provides the following method for improving the rejection of a permeable membrane, a permeable membrane, a permeable membrane treatment method, and a permeable membrane device.
(1) A method for improving the rejection rate of a permeable membrane, comprising improving the rejection rate of a permeable membrane by contacting a permeable membrane with a rejection rate improving agent to which an electrolyte is added so as to have a concentration of 1000 to 10000 mg / L.
(2) After performing the blocking rate improver treatment for improving the blocking rate of the permeable membrane by bringing the blocking rate improving agent added with an electrolyte so that the concentration becomes 1000 to 10000 mg / L into contact with the permeable membrane,
A first immobilizing agent containing a polymer having a weight average molecular weight larger than that of the blocking rate improver and a weight average molecular weight larger than that of the blocking rate improving agent, The method for improving the rejection of the permeable membrane according to (1), wherein the second fixing agent containing an ionic polymer different from the fixing agent is alternately contacted once or more to perform the fixing agent treatment.
(3) The method according to (1) or (2) above, wherein the rejection rate improver is cationic or anionic.
(4) The method according to any one of (1) to (3) above, wherein the rejection rate improver is a compound having a polyalkylene glycol chain.
(5) When the rejection rate improver is cationic, the first immobilization agent is anionic, the second immobilization agent is cationic, and when the rejection rate improver is anionic, the first immobilization The method according to any one of (2) to (4) above, wherein the agent is cationic and the second fixing agent is anionic.
(6) The method according to any one of (2) to (5) above, wherein the rejection rate improver, the first fixing agent, and the second fixing agent are each added with an electrolyte.
(7) The method according to any one of (1) to (6) above, wherein the electrolyte is selected from sodium chloride, calcium chloride, sodium sulfate and magnesium sulfate.
(8) A permeable membrane obtained by the method according to any one of (1) to (7) above.
(9) A permeable membrane treatment method in which a permeable membrane treatment is performed by allowing a liquid to be treated to permeate a permeable membrane obtained by the method according to any one of (1) to (7) above.
(10) A permeable membrane treatment apparatus that performs a permeable membrane treatment by using a permeable membrane obtained by the method according to any one of (1) to (7) above and allowing a liquid to be treated to permeate the permeable membrane.
(11) a permeable membrane module for passing the liquid to be treated on the primary side and taking out the permeate from the secondary side;
A rejection rate improver treatment apparatus for performing a rejection rate improver treatment by passing a rejection rate improver mainly composed of an organic substance through the primary side of the module;
An electrolyte addition device for adding an electrolyte to the rejection rate improver so as to have a concentration of 1000 to 10000 mg / L;
On the primary side of the module, a first immobilizing agent containing a polymer having a weight average molecular weight larger than that of the blocking rate improver, and a first immobilizing agent having a weight average molecular weight larger than that of the blocking rate improving agent, A permeable membrane device comprising: a second fixing agent containing different ionic polymers, and an immobilizing agent treatment device that performs the immobilizing agent treatment by alternately passing one or more times.

  In the present invention, the permeation membrane to be subjected to the rejection improvement process is a permeation membrane that allows the liquid to be treated to pass through the primary side and permeate it, and removes the permeate from the secondary side to perform membrane separation. Selective permeable membranes that separate inorganic electrolytes such as osmotic membranes and nanofiltration membranes and water-soluble organic substances from water are suitable as targets. A reverse osmosis membrane (RO membrane) is a liquid separation membrane that applies a pressure higher than the osmotic pressure difference between solutions through the membrane to the high concentration side to block the solute and permeate the solvent.

  Examples of the membrane structure of the permeable membrane, particularly the RO membrane, include polymer membranes such as composite membranes and phase separation membranes. Examples of the material of the permeable membrane, particularly the RO membrane, applied to the present invention include polyamide-based materials such as aromatic polyamides, aliphatic polyamides, and composite materials thereof. Among these, the rejection improvement processing according to the present invention can be suitably applied to aromatic polyamide permeable membranes, particularly RO membranes. The permeation membrane to be subjected to such a rejection improvement process may be an unused permeation membrane or a permeation membrane whose performance has been degraded by use.

  The rejection rate improving process and the fixing agent process in the present invention are performed on the permeable membrane in a state where such a permeable membrane is mounted on the module of the membrane separation apparatus or not mounted on the module. There is no restriction | limiting in particular about the form of RO membrane module, For example, a tubular membrane module, a planar membrane module, a spiral membrane module, a hollow fiber membrane module etc. are applicable.

  In the case of an unused permeable membrane, or in the case of a permeable membrane whose performance has deteriorated due to use, the permeable membrane that has been subjected to chemical cleaning can be the target of the rejection rate improving treatment. In the case of a permeable membrane whose performance has deteriorated due to the above, it is preferable to perform chemical cleaning. The purpose of the chemical cleaning is to make it easy for the blocking rate improver to be adsorbed on the membrane itself by removing contaminants on the membrane surface. Cleaning chemicals include acids (hydrochloric acid, nitric acid, oxalic acid, citric acid, etc.), alkalis (potassium hydroxide, sodium hydroxide, etc.), surfactants (sodium dodecyl sulfate, sodium dodecylbenzene sulfate, etc.), oxidizing / reducing agents ( Hydrogen peroxide, percarbonate, peracetic acid, sodium bisulfite, etc.) are used, and cleaning is generally performed by passing an aqueous solution of these chemicals through a module or immersing a permeable membrane in the chemicals.

  The rejection improving agent in the present invention is a rejection improving agent mainly composed of an organic substance. The rejection improving treatment improves the rejection of soluble substances such as water-soluble organic substances and inorganic electrolytes by the permeable membrane. If it is, it can be used without particular limitation. Examples of such a blocking rate improver are water-soluble polymer compounds, which include ionic or nonionic polymers, and ionic polymers having a weight average molecular weight of 100,000 or more are preferable. In the case of an ionic polymer, a cationic polymer, an anionic polymer, an amphoteric polymer, etc. can be used alone, but when a cationic polymer and an anionic polymer are supplied stepwise, preferably alternately, This is preferable because the effect of improving the rejection is increased. By using these compounds as the main component of the blocking rate improver, the blocking rate of the RO membrane is improved, and electrolytes, low molecular weight nonionic organic substances that have been difficult to remove with conventional RO membranes, boron, Silica and the like can also be effectively removed.

  Examples of the blocking rate improver that can be used include compounds having a polyalkylene glycol chain and compounds having a plurality of phenolic hydroxyl groups. As these, known ones can be used, and those described in Patent Documents 1 to 3 as well as those having other ability to improve the rejection rate can be used. Usable blocking rate improvers include water-soluble polymers such as polyvinyl methyl ether, polyvinyl alcohol, and polyethyleneimine, polyphenols such as tannic acid, ionic polymers described in Patent Document 3 (polyamidine, polystyrene sulfonic acid), Examples thereof include compounds having a polyethylene glycol chain having a weight average molecular weight of 2000 to 6000 described in Patent Document 1. Examples of the compound having a polyalkylene glycol chain include polyethylene glycol or polyethylene glycol derivatives.

Preferable blocking rate improvers include compounds having a polyalkylene glycol chain. Although the weight average molecular weight of the compound which has a polyalkylene glycol chain is not specifically limited, Preferably it is 1000-10000, More preferably, it is 2000-6000, More preferably, it is 3000-5000.
In the present invention, the weight average molecular weight is obtained by analyzing an aqueous solution of a compound such as a polymer or a compound having a polyalkylene glycol chain by gel permeation chromatography and converting the obtained chromatogram into the molecular weight of a polyethylene oxide standard product. be able to. In a high molecular weight region where a polyethylene oxide standard product cannot be obtained, the weight average molecular weight can be determined by a light scattering method, an ultracentrifugation method, or the like.

  The polyalkylene glycol chain can be produced by ring-opening polymerization of alkylene oxide. Examples of the polyalkylene glycol chain of the compound used in the present invention include a polyethylene glycol chain, a polypropylene glycol chain, a polytrimethylene glycol chain, and a polytetramethylene glycol chain. These glycol chains can be formed by, for example, ring-opening polymerization of ethylene oxide, propylene oxide, oxetane, tetrahydrofuran or the like. The polyalkylene glycol chain is preferably a polyethylene glycol chain. The compound having a polyethylene glycol chain is easy to handle as a blocking rate improver because of its high water solubility.

In the present invention, as the compound having a polyalkylene glycol chain, a compound having an ionic group introduced into the polyalkylene glycol chain is preferably used. Examples of the ionic group include a sulfo group (—SO ₃ H), a carboxyl group (—COOH), an amino group (—NH ₂ ), a quaternary ammonium group (—N ⁺ R ₃ X ⁻ ), and the like. it can. Of these, anionic water-soluble polymer compounds can be obtained by introducing sulfo groups, carboxyl groups, etc., and cationic water-soluble polymer compounds can be obtained by introducing amino groups, quaternary ammonium groups, and the like. It is done.

  As a method for introducing a sulfo group into a polyalkylene glycol chain, for example, an epoxy propanol and sodium sulfite are added to a polyethylene glycol aqueous solution and reacted under a reflux condition at 70 to 90 ° C. The sulfonated polyethylene glycol represented by 2] can be synthesized, but the compound represented by the formula [3] or the formula [4] can also be used.

_{H (OCH 2 CH 2) pO} (CXH-CYHO) q-SO 3 Na ··· [1]
_{NaSO 3 - (OCXH-CYH)} q- (OCH 2 CH 2) pO (CXH-CYHO) q-SO 3 Na ··· [2]
_{H (OCH 2 CH 2) p} -O-SO 3 Na ··· [3]
_{NaSO 3 - (OCH 2 CH 2} ) q-O-SO 3 Na ··· [4]
(In the formula [1] to the formula [4], X, Y are each independently H or _CH 2 OH, p is independently 50 to 150, q is 1 to 100 independently.)

  These blocking rate improvers are selected according to the material, form, etc. of the permeable membrane to be treated, and are used after being dissolved in a solvent such as pure water or treated water. The concentration of the blocking rate improver varies depending on the permeable membrane, module type, etc., but is generally adjusted to a concentration of about 0.01 to 1000 mg / L, preferably 0.1 to 100 mg / L. To be improved. A plurality of blocking rate improvers can be used in combination, and in this case, they may be mixed and passed, or may be passed separately while shifting the time.

  In the present invention, the rejection rate improver used for the rejection rate improvement treatment is an aqueous solution to which an electrolyte is added so as to have a concentration of 1000 to 10000 mg / L, preferably 2000 to 5000 mg / L. Since the ionicity blocking rate improvers repel each other due to their ionicity, they cannot be modified precisely, and the blocking rate improving effect is limited. Therefore, by adding an electrolyte and neutralizing the charge of the rejection rate improving agent to suppress repulsion, it becomes possible to modify more precisely than in the case of no addition. As the electrolyte, metal salts such as sodium chloride, calcium chloride, sodium sulfate, and magnesium sulfate can be used. Particularly, divalent or higher metal salts such as calcium chloride and magnesium sulfate are preferable because the effect is obtained at a low concentration. . When the electrolyte concentration is lower than the above concentration, the effect of improving the rejection is not observed. When the electrolyte concentration is higher than the above concentration, the polymer aggregates and cannot be precisely modified.

  In the rejection rate improving process using the rejection rate improving agent to which the electrolyte is added, the rejection rate improving agent is supplied and brought into contact with the permeable membrane of the module to be processed to improve the rejection rate of the permeable membrane. At this time, the surface of the permeable membrane is modified by the rejection rate improver, but the presence of the electrolyte can suppress the spread of the rejection rate improver in water and can be modified precisely, thereby enhancing the effect of improving the rejection rate. it can. In this case, by setting the electrolyte concentration to 1000 to 10000 mg / L, preferably 2000 to 5000 mg / L, the effect of improving the rejection rate is much higher than when a conventional electrolyte is used as a tracer substance at a concentration of about 500 mg / L. Can be obtained. This effect is particularly remarkable when the rejection rate improver is an ionic rejection rate improver, but is also observed in nonionic rejection rate improvers such as polyethylene glycol.

  A blocking rate improver is supplied to the primary side of the module to which the permeable membrane is attached, and the blocking rate improving agent is attached to the permeable membrane, thereby improving the blocking rate of the permeable membrane. When using a blocking rate improver with high adsorptivity to the permeable membrane, the blocking rate improving agent can be supplied to the module and kept in contact with the permeable membrane, or can be adsorbed by flowing at a low pressure, In general, it is preferable to attach the rejection improving agent to the inside of the permeable membrane by supplying the rejection improving agent at a high pressure to permeate the permeable membrane and take out the permeate from the secondary side.

  It is preferable that the time per one time of passing the aqueous solution containing the blocking ratio improver to which the electrolyte is added is 1 to 24 hours. When the concentration of the blocking ratio improver in the aqueous solution is increased, the water passage time can be shortened, but the permeation flux may be greatly reduced. When passing an aqueous solution containing this blocking rate improver, it is possible to close the permeable water discharge valve of the module. However, if the permeable water is taken out, it can be processed efficiently without stopping the device. In addition, the blocking rate improver can be efficiently and uniformly adsorbed on the permeable membrane surface. In this case, the operation pressure when supplying the aqueous solution containing the rejection improving agent to the primary side of the module is 0.3 MPa or more, and the ratio of the amount of permeated water / the amount of aqueous solution containing the rejection improving agent is 0.2. The above is preferable. Thereby, since the blocking rate improver effectively contacts the permeable membrane surface, the blocking rate improving agent can be adsorbed on the membrane surface efficiently and uniformly.

  In the present invention, after the blocking rate improver treatment that improves the blocking rate of the permeable membrane by bringing the blocking rate improver added with an electrolyte into contact with the permeable membrane, the permeable membrane that has been subjected to the blocking rate improver treatment, A first immobilizing agent comprising a polymer having a weight average molecular weight greater than that of the blocking rate improver; and an ionic polymer having a weight average molecular weight greater than that of the blocking rate improving agent and different from that of the first immobilizing agent. The fixing agent treatment can be performed by alternately contacting the second fixing agent to be contained once or more. The immobilizing agents that can be used as the first and second immobilizing agents include water-soluble polymers having a weight average molecular weight of 100,000 or more, particularly 300,000 or more, and more than 1 million, and are ionic and nonionic. Although it does not ask | require, it is especially preferable that it is an ionic polymer. When the weight average molecular weight is less than 100,000, it is difficult to stably adsorb the blocking rate improver on the permeable membrane and maintain the state for a long time. Examples of the ionic polymer include a cationic polymer and an anionic polymer, and the fixing agent treatment is performed by alternately contacting the first and second fixing agents made of these one or more times.

  Examples of the cationic polymer used in the fixing agent of the present invention include primary amine compounds such as polyvinylamine, polyallylamine, polyacrylamide, chitosan, and those obtained by adding a primary amine group to polystyrene, and polyethylenimine. Tertiary amine compounds such as diamine compounds, poly (dimethylaminoethyl acrylate) and poly (dimethylaminoethyl methacrylate), quaternary ammonium compounds such as those obtained by adding a quaternary ammonium group to polystyrene, polyvinylamidine, polyvinylpyridine And compounds having a heterocyclic ring such as polypyrrole and polyvinyldiazole. Moreover, the copolymer polymer which has these structures, and the composition which mixed multiple types of polymer | macromolecule can also be used.

  Among these, compounds having a heterocyclic ring can be preferably used, and polyvinylamidine can be particularly preferably used. Polyvinylamidine is a cationic polymer having a structural unit represented by the general formula [5]. However, in General formula [5], R1-R4 is hydrogen or alkyl groups, such as a methyl group.

  The cationic polymer having the structural unit represented by the general formula [5] includes acrylonitrile or methacrylonitrile, N-vinylcarboxylic acid amide, N-isopropenylcarboxylic acid amide, N-vinylcarboxylic acid imide, or N- It can be produced by copolymerizing with isopropenyl carboxylic acid imide and hydrolyzing the resulting copolymer polymer to amidine. In addition to the structural unit represented by the general formula [5], the polyvinylamidine produced by such a method includes a cyano group derived from acrylonitrile and the like, a carbamoyl group generated by hydrolysis of the cyano group, and N-vinylcarboxylic acid. It has an amino group generated by hydrolysis of an acid amide unit or the like. As a commercially available product, there is a cationic polymer flocculant “Krifix (registered trademark) CP111” manufactured by Kurita Kogyo Co., Ltd. Polyvinylamidine can be strongly stabilized because the nitrogen atom of the heterocyclic ring and the nitrogen atom of the primary amine are cationic, so that the cation density is high and there are many reaction points. Moreover, a high rejection improvement effect is expressed with respect to the cationic species in water. In the case of a polymer having another heterocyclic ring, the cation density can be increased by adding a cationic functional group such as a primary amine.

  Examples of the anionic fixing agent used in the present invention include water-soluble polymers having a carboxyl group such as polyacrylic acid and polymethacrylic acid, and water-soluble polymers having a sulfonic acid group such as polystyrene sulfonic acid, dextran sulfuric acid, and polyvinyl sulfonic acid. And a copolymer having a plurality of these structures can also be used. Since the sulfonic acid group of polystyrene sulfonic acid has strong anionic property, it can be stably adsorbed on the membrane surface of the permeable membrane and can be firmly stabilized without greatly reducing the permeation flux.

  The ionic polymer used as the fixing agent of the present invention can be used as a salt having a counter ion in both cases of the cationic fixing agent and the anionic fixing agent. Examples of the salt having a counter ion include polyvinylamidine hydrochloride, polyacrylic acid sodium salt, and polystyrenesulfonic acid sodium salt.

  These immobilizing agents are selected according to the material and form of the permeable membrane to be treated, the blocking rate improver used, etc., and are dissolved in a solvent such as pure water or water to be treated. Used as a liquid. The treatment liquid containing the fixing agent used in the present invention is used as an aqueous solution of the water-soluble polymer. The concentration of the water-soluble polymer in the treatment liquid is about 0.01 to 50 mg / L. The more preferable compound concentration of the aqueous solution containing the immobilizing agent varies depending on the type of the compound to be used. For example, in the case of a cationic polymer having a weight average molecular weight of 100,000 or more, an anionic polymer, 0.1 to 10 mg / L is preferable. . If the concentration is lower than this, the treatment with the fixing agent may take a long time. When the concentration exceeds 50 mg / L, the viscosity of the aqueous solution increases, and there is a possibility that the resistance to water flow to the RO membrane increases. On the other hand, when the concentration exceeds 50 mg / L, an unnecessarily thick coating layer (adsorption layer) is formed, and the effect of improving the rejection rate may be weakened due to concentration polarization.

  When the permeable membrane is treated with a fixing agent, as in the case of a blocking rate improver, the effect of improving the blocking rate after treatment can be improved by adding an electrolyte as a charge neutralizing substance to the fixing agent. . The same applies to the case where an electrolyte is added to the immobilizing agent and the rejection improvement process is performed. When a plurality of fixing agents are combined and processed alternately, an electrolyte can be added to one or all of the respective fixing agents. As the electrolyte to be added to the fixing agent, the same electrolyte as that added to the inhibition rate improver can be added and used at the same concentration. When the immobilization agent containing the electrolyte is used to immobilize the rejection rate improving agent, the presence of the electrolyte neutralizes the charge of the immobilization agent and modifies the surface of the permeable membrane. Alternatively, the immobilizing agent and the immobilizing agent to be treated later can be in close contact with each other to make a strong modification, and the effect of improving the rejection rate can be enhanced. At this time, by setting the concentration of the electrolyte to 1000 to 10000 mg / L, preferably 2000 to 5000 mg / L, the effect of improving the rejection rate is much higher than when the conventional electrolyte is used as a tracer substance at a concentration of about 500 mg / L. Can be obtained.

  In the rejection rate improving method of the present invention, the permeation membrane that has been subjected to the rejection rate improvement treatment is further brought into contact with a treatment liquid containing a fixing agent. This can be carried out following the rejection rate improving treatment, and after stopping the passage of the rejection rate improving agent, or after discharging the rejection rate improving agent, the fixing agent can be passed through to perform the fixing agent treatment. . In this case, it is preferably carried out by passing a treatment liquid containing a fixing agent on the primary side of the module.

  The immobilization agent treatment is a first immobilization treatment in which a first immobilization agent containing a polymer having a weight average molecular weight larger than that of the inhibition rate improver is brought into contact with the permeable membrane that has been subjected to the inhibition rate improvement agent treatment; The second immobilization treatment in which a second immobilization agent containing an ionic polymer different from the first immobilization agent is contacted is alternately performed once or more. The first fixing agent is preferably an ionic one different from the blocking rate improver. For example, when the rejection improving agent is cationic, the first immobilizing agent is anionic, and the second immobilizing agent is cationic, and when the rejection improving agent is anionic, the first immobilization agent is immobilized. Preferably, the agent is cationic and the second immobilizing agent is anionic and alternately treated with the opposite ionic polymer.

  In the immobilization agent treatment, for example, a case where the rejection rate improving process is performed with a rejection rate improving agent made of a compound having an ionic polyalkylene glycol chain as the rejection rate improving agent will be described. It is preferable to use two agents, a first immobilizing agent composed of anionic polymer and a second immobilizing agent composed of an anionic polymer, alternately. That is, as the order of treatment, if the rejection rate improver is cationic, the immobilizing agent is used from the anionic immobilizing agent, and if the rejection rate improving agent is anionic, it is used from the cationic immobilizing agent. It is desirable. As a result, the blocking rate improver and the immobilizing agent can form an ion complex, and the blocking rate improving agent is firmly held on the surface of the permeable membrane, and the performance can be maintained over a long period of time.

  For example, by treating with a compound having a polyalkylene glycol chain introduced with a sulfo group as described above as a compound having a polyalkylene glycol chain as a blocking rate improver, and then treating with a cationic fixing agent as a first fixing agent The blocking rate anti-blocking agent and the immobilizing agent form an ion complex, and the blocking rate improving agent can be firmly held on the RO membrane surface. Thereafter, the stability is further improved by further treatment with an anionic fixing agent as a second fixing agent. Thereafter, the stability can be improved by alternately treating with a cationic fixing agent and an anionic fixing agent.

  There is no limit to the number of times the treatment is alternately performed with the cationic immobilizing agent and the anionic immobilizing agent, and the treatment can be repeated alternately as necessary. When the rejection improving agent is cationic, for example, when the compound having a polyalkylene glycol chain has a quaternary ammonium group, an anionic fixing agent is used as the first fixing agent, and the second fixing agent is used. Stability can be obtained in the same manner by using a cationic immobilizing agent and alternately processing.

  The blocking rate improver and immobilizing agent used in the present invention can be used as a blocking rate confirmation tracer substance for the added electrolyte, but other blocking agents such as water-soluble organic compounds can be used even when the electrolyte is not added or added. A rate confirmation tracer material can be included. By passing water through a permeation membrane such as a nanofiltration membrane or a reverse osmosis membrane, a rejection rate improver or immobilizing agent added with such a tracer substance is used to confirm the rejection rate of the permeation membrane over time. Can continue or stop. The water treatment time is usually preferably 1 to 50 hours, more preferably 2 to 24 hours, but when the tracer concentration of the permeated water reaches a predetermined value, the rejection rate of the permeable membrane Can be determined to have reached a predetermined value, and the inhibition rate improving agent treatment or the fixing agent treatment can be terminated.

According to this method, the contact time between the aqueous solution of the rejection rate improving agent or the fixing agent and the permeable membrane can be controlled to a necessary and sufficient minimum length, and normal operation of the permeable membrane can be started immediately. it can. Also, when multiple rejection rate improver treatments or immobilization agent treatments are performed using different rejection rate improvers or immobilizing agents, multiple treatments can be efficiently performed without losing the timing of switching. Can do.
Examples of the water-soluble organic compound used as a tracer substance other than the electrolyte include isopropyl alcohol, glucose, urea, and the like, but isopropyl alcohol is preferable because of ease of handling. The concentration of the tracer substance is preferably 1 to 5,000 mg / L, more preferably 5 to 1,000 mg / L in the case of a water-soluble organic substance such as isopropyl alcohol.

The permeable membrane obtained by the above-described blocking rate improving method has a high effect of improving the blocking rate of the permeable membrane by the blocking rate improving agent, and can maintain the high state for a long time.
The permeable membrane of the present invention is a permeable membrane obtained by the above-described method for improving the rejection rate. The effect of improving the rejection rate of the permeable membrane by the rejection rate improving agent is high, and the high state can be maintained for a long time.

  The permeable membrane treatment method of the present invention is a permeable membrane treatment method for carrying out a permeable membrane treatment by allowing a liquid to be treated to permeate the permeable membrane obtained by the above-described method for improving the rejection rate. The improvement effect is high, and the high state can be maintained for a long time, the organic matter removal effect is high, and stable treatment is possible over a long period of time.

  The permeation membrane processing apparatus of the present invention is a permeation membrane processing device that uses a permeation membrane obtained by the above-described method for improving the rejection rate and permeates the permeation membrane by permeating the treatment liquid. By performing the permeable membrane treatment by permeating the liquid, the effect of improving the rejection rate of the permeable membrane by the rejection rate improver is high, and the high state can be maintained for a long time, the organic matter removal effect is high, and over a long period of time Stable processing is possible.

  A preferred permeable membrane treatment apparatus of the present invention is a permeable membrane module for passing a liquid to be treated on the primary side and taking out the permeate from the secondary side, and an improvement in the rejection rate mainly composed of organic substances on the primary side of the module. A blocking rate improver treatment apparatus for performing blocking rate improver treatment by passing an agent, and an electrolyte in which an electrolyte is added to the blocking rate improver to a concentration of 1000 to 10000 mg / L, preferably 2000 to 5000 mg / L On the primary side of the addition device and the module, a first immobilizing agent containing a polymer having a weight average molecular weight larger than that of the blocking rate improver, and a first fixing agent having a weight average molecular weight larger than that of the blocking rate improving agent. And a second fixing agent containing an ionic polymer that is different from the first agent, and a second fixing agent that alternately passes one or more times to perform a fixing agent treatment device.

  In the above permeable membrane treatment apparatus, the liquid to be treated is passed through the primary side of the permeable membrane module, the permeate is taken out from the secondary side, and the permeable membrane treatment is performed. When blocking rate improver treatment is performed by passing a blocking rate improver mainly composed of an organic substance on the side, the electrolyte is blocked to a concentration of 1000 to 10000 mg / L, preferably 2000 to 5000 mg / L, using an addition device. The electrolyte is added to the rate improver to perform the rejection rate improver treatment, and the first fixative and the second fixative are alternately applied to the primary side of the module one or more times by the fixative treatment apparatus. The blocking rate of the permeable membrane can be improved by passing the solution and performing the fixing agent treatment.

  According to the present invention, since the blocking rate improver to which the electrolyte is added so as to have a concentration of 1000 to 10000 mg / L is brought into contact with the permeable membrane, the blocking rate improving agent has a high effect of improving the blocking rate by the blocking rate improving agent. At the same time, it can be maintained in a state where the effect of improving the rejection rate is high, so that the organic matter removing effect is high and stable treatment is possible over a long period of time.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 are flowcharts showing a permeable membrane processing method and apparatus according to an embodiment of the present invention.

  1 and 2, reference numeral 1 denotes an RO membrane module, which is divided into a primary side 3 and a secondary side 4 by an RO membrane 2 as a permeable membrane. 11 is a treated water tank, 12 is a treated water tank, 13 is an alkaline cleaning liquid tank, 14 is an acidic cleaning liquid tank, 15 is a rejection rate improving agent aqueous solution tank, 16 is a first fixing agent aqueous solution tank, and 17 is a second fixing. Aqueous agent solution tank, 18 is an electrolyte solution tank, P1 is a high pressure pump, P2 is a cleaning solution pump, P3 is a rejection rate improving agent aqueous solution pump, P4 is a first fixing agent aqueous solution pump, and P5 is a second fixing agent aqueous solution. Pump P6 is an electrolyte solution pump. V1 to V35 are valves. 1 and 2 show main piping and valves, and other valves, gauges, and piping are not shown.

  In FIGS. 1 and 2, when the water to be treated is subjected to RO treatment, the valves V1 to V5 and V9 are opened, the other valves are closed, the high pressure pump P1 is operated, and the water in the treated water tank 11 is closed. Treated water is supplied to the primary side 3 of the RO membrane module 1 and subjected to membrane separation by the RO membrane 2, and permeate is taken out of the system from the secondary side. The concentrated water is returned from the primary side 3 to the water tank 11 to be treated, and a part thereof is discharged out of the system through the valve V3 in order to prevent the concentration of the RO feed water. Further, the valves V6 and V7 are opened, and the permeate is stored in the treated water tank 12. In some cases, the valves V11 to V15 are opened, and the permeated water is passed through the alkaline cleaning liquid tank 13, the acidic cleaning liquid tank 14, the rejection rate improving agent aqueous solution tank 15, the first fixing agent aqueous solution tank 16, and the second fixing agent aqueous solution tank 17. And can be used for dilution, adjustment, etc. of a cleaning solution or a polymer aqueous solution.

  When the permeation flux of the RO membrane 2 is reduced by performing the RO treatment as described above, when performing chemical cleaning, the high-pressure pump P1 is stopped and the valves V2, V4, V21, and V31 are opened. The other valves are closed, the cleaning liquid pump P2 is operated, the alkaline cleaning liquid in the alkaline cleaning liquid tank 13 is introduced into the primary side 3 of the RO membrane module 1, and then circulated back into the alkaline cleaning liquid tank 13 again. Let At this time, the valve V5 may be opened to allow part of the cleaning liquid to pass through the membrane and be discharged out of the system. Alternatively, the cleaning liquid having passed through the membrane may be returned to the alkaline cleaning liquid tank 13 by opening the valves V6 and V11. After circulating the alkaline cleaning liquid for a predetermined time, in some cases, the cleaning liquid pump P2 is stopped and the chemical liquid is allowed to stand for a certain period of time, and then the drain pipe (not shown) provided with the alkaline cleaning liquid in the alkaline cleaning tank 13 (not shown) ) To the outside of the system.

  Next, the valves V2, V4, V22, V32 are opened, the other valves are closed, and the acidic cleaning liquid in the acidic cleaning liquid tank 14 is introduced into the primary side 3 of the RO membrane module 1, and then returned to the acidic cleaning liquid tank 14 again. Circulate. At this time, the valve V5 may be opened to allow a part of the cleaning liquid to pass through the membrane and be discharged out of the system. Alternatively, the cleaning liquid having passed through the membrane may be returned to the acidic cleaning liquid tank 14 by opening the valves V6 and V12. After circulating the acidic cleaning liquid for a predetermined time, the drain pipe (not shown) provided with the acidic cleaning liquid in the acidic cleaning liquid tank 14 after stopping the cleaning liquid pump P2 and keeping the chemical liquid still for a predetermined time in some cases. To the outside of the system.

  Next, the valves V2, V3, V8 are opened, the other valves are closed, the primary side 3 of the RO membrane module 1 is washed with the treated water in the treated water tank 12, and the washing drainage is discharged outside the system through the valve V3. Discharge. In this case, the valve V3 may be closed, the valve V21 or V22 and the valve V4 may be opened, and the cleaning waste liquid may be discharged from drain pipes (not shown) provided in the cleaning liquid tanks 13 and 14. This cleaning (rinsing) with the treated water can be performed between the cleaning with the alkaline cleaning liquid and the cleaning with the acidic cleaning liquid. Either the cleaning with the alkaline cleaning liquid or the cleaning with the acidic cleaning liquid may be performed first, or may be repeated twice or more alternately.

  In FIG. 1, when a rejection rate improving treatment is performed using a rejection rate improving agent to which an electrolyte is added, a compound (hereinafter referred to as “PEG”) aqueous solution having a polyethylene glycol chain as a rejection rate improving agent in the rejection rate improving agent aqueous solution tank 15. The electrolyte solution tank 18 is filled with the electrolyte solution. Then, the valves V2, V4, V23, V33 and V16 are opened, the other valves are closed, and the cleaning pump P2 and the electrolyte solution pump P6 are operated so that the electrolyte solution from the electrolyte solution tank 18 has a predetermined concentration. While adding, the PEG aqueous solution in the rejection rate improving agent aqueous solution tank 15 is introduced into the primary side 3 of the RO membrane module 1 and then circulated so as to be returned to the tank 15 again. At this time, the valve V5 may be opened to allow a part of the PEG aqueous solution to pass through the membrane and be discharged out of the system, but the valves V6 and V13 may be opened to return the membrane-penetrated PEG aqueous solution into the tank 15. Is preferred. After circulating the PEG aqueous solution for a predetermined time, the PEG aqueous solution is discharged out of the system through a drain pipe (not shown) provided in the rejection rate improving agent aqueous solution tank 15.

  The treatment with the fixing agent is performed in the same manner. First, the case where the treatment is performed with two kinds of fixing agents without adding the electrolyte will be described. In this case, the first fixing agent aqueous solution tank 16 is filled with a cationic polymer polyvinylamidine aqueous solution as a first fixing agent, and the second fixing agent aqueous solution tank 17 is filled with an anionic polymer polystyrenesulfonic acid aqueous solution. After the valves V2, V4, V24 and V34 are opened and the other valves are closed, the aqueous cationic polymer polyvinylamidine solution in the first fixing agent aqueous solution tank 16 is introduced into the primary side 3 of the RO membrane module 1. Then, it is circulated so as to return to the first fixing agent aqueous solution tank 16 again. At this time, the valve V5 may be opened to allow a part of the aqueous solution to permeate through the membrane and be discharged out of the system. However, the valves V6 and V14 may be opened to allow the membrane-permeated polymer aqueous solution to pass through the first fixing agent aqueous solution tank. It is preferable to return to 16. After the cationic polymer aqueous solution is circulated for a predetermined time, the cationic polymer aqueous solution is discharged out of the system through a drain pipe (not shown) provided in the first fixing agent aqueous solution tank 16.

  Next, the valves V2, V4, V25 and V35 are opened, and the other valves are closed, and the anionic polymer polystyrene sulfonic acid aqueous solution in the second fixing agent aqueous solution tank 17 is introduced into the primary side 3 of the RO membrane module 1. Then, it is circulated so as to return to the second fixing agent aqueous solution tank 17 again. At this time, the valve V5 may be opened to allow a part of the aqueous solution to pass through the membrane and be discharged out of the system. However, the valves V6 and V15 may be opened to pass the membrane-permeable polymer aqueous solution to the second fixing agent aqueous solution tank. 17 is preferably returned. After the anionic polymer aqueous solution is circulated for a predetermined time, the anionic polymer aqueous solution is discharged out of the system through a drain pipe (not shown) provided in the second fixing agent aqueous solution tank 17.

  Next, the valves V2, V3, V6, V8 are opened, and at least one of the valves V13, V14, V15 is opened, the other valves are closed, and the primary of the RO membrane module 1 is treated with treated water in the treated water tank 12. The side 3 is cleaned, and a part of the cleaning drainage is discharged out of the system through the valve V3, and the remaining part is discharged out of the system through one of the tanks 15, 16, and 17.

  When performing the immobilization process while adding the electrolyte, the electrolyte solution pump P6 is operated, the valve V16 is opened, and the electrolyte solution is supplied from the electrolyte solution tank 18 to the first fixing agent or the second solution so that the electrolyte solution has a predetermined concentration. 2. Wash while adding to the immobilizing agent. Washing (rinsing) with treated water or electrolyte-added treated water is preferably carried out between the treatment with a blocking rate improver, the treatment with an aqueous cationic fixative solution, and the treatment with an aqueous anionic fixative solution.

  FIG. 2 shows that RO treatment is performed by passing the water to be treated, and a blocking rate improver, the first fixing agent or the second fixing agent is added to the water to be treated, and the treatment with these treatment agents is performed. An example is shown. In FIG. 2, when the rejection rate improving process is performed using PEG as the rejection rate improving agent to which an electrolyte is added, for example, an aqueous solution of PEG is added to the aqueous solution rate stopping agent tank 15, and an electrolyte solution is added to the electrolyte solution tank 18. Fulfill. Further, when the immobilization treatment is performed by adding the first immobilizing agent or the second immobilizing agent, the cationic polymer aqueous solution is added to the first immobilizing agent aqueous solution tank 16 and the second immobilizing agent aqueous solution tank 17, respectively. Fill the anionic polymer solution.

  In order to perform the rejection rate improving agent treatment by adding the rejection rate improving agent to which the electrolyte is added to the water to be treated, first, the valve P33 is opened, the pump P3 is operated, and the aqueous PEG solution in the rejection rate improving agent aqueous solution tank 15 is operated. Is then introduced into the water tank 11 to be treated, and then the high-pressure pump P1 and the electrolyte solution pump P6 are operated to open the valves V1, V2, V4, V9 and V16, and the other valves are closed. While adding the solution to a predetermined concentration, the PEG aqueous solution in the treated water tank 11 is introduced 3 into the primary side of the RO membrane module 1 and then circulated back to the tank 11 again. At this time, it is preferable that the valves V3 and V5 are opened to allow a part of the PEG aqueous solution to pass through the membrane to obtain treated water and to discharge a part of the PEG aqueous solution out of the system. By doing in this way, the time which stops the driving | operation of RO processing apparatus can be shortened. After circulating the PEG aqueous solution for a predetermined time, the valve V33 is closed and the pump P3 is stopped to stop the introduction of the PEG aqueous solution.

  In FIG. 2, after the treatment with the rejection rate improving agent, when the first fixing agent and the second fixing agent are added to the liquid to be treated without adding the electrolyte, the valve V34 is opened. The pump P4 is operated, the cationic polymer aqueous solution in the first fixing agent aqueous solution tank 16 is introduced into the water tank 11 to be treated, and then the high pressure pump P1 is operated to open the valves V1, V2, V4, V9, The other valves are closed, and the cationic polymer aqueous solution in the water tank 11 to be treated is introduced into the primary side 3 of the RO membrane module 1 and then circulated back into the tank 11 again. At this time, it is preferable that the valves V3 and V5 are opened so that part of the polymer aqueous solution is permeated through the membrane to obtain treated water, and part of the polymer aqueous solution is discharged out of the system. By doing in this way, the time which stops the driving | operation of RO processing apparatus can be shortened. After circulating the cationic polymer aqueous solution for a predetermined time, the valve V34 is closed and the pump P4 is stopped to stop the introduction of the cationic polymer aqueous solution.

  Next, the valve V35 is opened, the pump P5 is operated, the cationic polymer aqueous solution in the second fixing agent aqueous solution tank 17 is introduced into the water tank 11 to be treated, and then the high-pressure pump P1 is operated, and the valves V1, V2 , V4, V9 are opened, the other valves are closed, and the cationic polymer aqueous solution in the treated water tank 11 is introduced into the primary side 3 of the RO membrane module 1 and then returned to the tank 11 again. Circulate. At this time, it is preferable to open the valves V3 and V5 to allow a part of the polymer aqueous solution to pass through the membrane to obtain treated water and to discharge a part of the polymer aqueous solution out of the system. By doing in this way, the time which stops the driving | operation of RO processing apparatus can be shortened. After circulating the cationic polymer aqueous solution for a predetermined time, the valve V35 is closed and the pump P5 is stopped to stop the introduction of the cationic polymer aqueous solution.

  It is desirable to carry out a washing step with treated water or electrolyte added treated water between the above treatment steps. That is, the valves V2, V3, and V8 are opened and the other valves are closed to stop the high-pressure pump P1, and the pump P2 is operated to treat the primary side 3 of the RO membrane module 1 with the treated water in the treated water tank 12. And the aqueous solution is discharged out of the system through the valve V3. In addition, after stopping the introduction of the aqueous solution for improving the rejection rate, the RO treatment is performed for a predetermined time (about three times the residence time of the water to be treated tank 11), so that the rinsing can be omitted or the time for the rinsing process. Can be shortened or the amount of rinse water can be reduced. The treatment with the cationic polymer aqueous solution and the anionic polymer carried out after the treatment with the PEG aqueous solution may be repeated twice or more alternately, but the treatment with the anionic polymer aqueous solution is preferred at the end.

  When the first fixing agent treatment, the second fixing agent treatment or the washing is performed while the electrolyte is added, the electrolyte solution pump P6 is operated, the valve V16 is opened, and the electrolyte solution is supplied from the electrolyte solution tank 18 to a predetermined amount. The first fixing agent treatment, the second fixing agent treatment or the washing is carried out while adding to the first fixing agent, the second fixing agent or the treated water so as to obtain a concentration. The operation at this time is the same as in the case of the treatment for improving the rejection rate. The concentration of the electrolyte is 1000 to 10000 mg / L, preferably 2000 to 5000 mg / L. The appropriate amount of addition is controlled by a densitometer or by a calculated value. By controlling the concentration of the electrolyte within the above range, it is possible to obtain a much higher rejection rate improvement effect than when a conventional electrolyte is used as a tracer substance at a concentration of about 500 mg / L.

  The above embodiment shows an example of the processing procedure of the RO membrane processing method of the present invention, and the present invention is not limited to this embodiment at all. The tank can be shared or omitted. Further, the RO membrane treatment process, the chemical cleaning process, and the inhibition ratio improvement treatment process may be performed in different places. That is, only the RO membrane module or element is removed from the vessel, moved from the location where the RO treatment process is performed to another location (for example, the RO membrane recycling plant), and stored in a separate vessel at the destination for chemical cleaning. You may implement a process process, a rejection rate improvement process process, etc.

  In the case of FIG. 2, the aqueous solution for improving the rejection rate is supplied to the treated water tank 11, and these rejection rate improving agents are connected to a pipe connecting the treated water tank 11 and the RO membrane module 1. The aqueous solution may be directly injected into the line. Furthermore, in the chemical cleaning step, only one of acid cleaning and alkali cleaning may be performed. Conversely, alkali cleaning may be performed after the acid cleaning.

  As the acid agent used for the acid cleaning, mineral acids such as hydrochloric acid, sulfuric acid and nitric acid, and organic acids such as citric acid and oxalic acid can be used. Sodium hydroxide, potassium hydroxide, sodium carbonate, etc. can be used as the alkali agent used for alkali cleaning. Further, an oxidizing agent such as hydrogen peroxide, a reducing agent such as sodium bisulfite, and a surfactant such as sodium alkylbenzene sulfonate can be added to these cleaning agents.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not limited at all by these Examples. In this example, the rejection rate was calculated by the following equation.
Blocking rate (%) = [1- (solute permeate concentration × 2) / (solute supply solution concentration + solute concentration)] × 100

[Example 1]:
As a blocking rate improver, an aqueous solution of polyethylene glycol 1 mmol / L having a weight average molecular weight of 4000, 2,3-epoxy-1-propanol 100 mmol / L and sodium sulfite 100 mmol / L is synthesized by refluxing at 80 ° C. for 20 minutes. A new membrane module of Nitto Denko's ultra-low pressure aromatic polyamide RO membrane “ES-20” by adding NaCl as an electrolyte to the sulfonated polyethylene glycol 0.1 mg / L aqueous solution to 2000 mg / L At a pressure of 0.75 MPa, the concentrated water and the permeated water were both circulated for 20 hours in a total circulation process for returning them to the water supply tank.
The RO membrane that has been treated is set in the RO membrane device, the pressure is 0.75 MPa, the amount of brine water is 1 m ³ / h, and a 1000 mg / L IPA (isopropyl alcohol) aqueous solution is passed through. The TOC concentration of feed water, concentrated water, and permeated water was measured, and the rejection rate of flux and IPA was calculated.

[Example 2]:
As the electrolyte to be added in Example 1, except that the addition of CaCl ₂ so that 2000 mg / L, performed in the same manner as in Example 1, were calculated flux and IPA rejection of the RO apparatus.

[Example 3]:
After carrying out the modification treatment with the blocking rate improver with the electrolyte added in Example 1, a polyvinylamidine 1 mg / L aqueous solution having a weight average molecular weight of 3 million was used as the first fixing agent aqueous solution for 20 hours, and then the second fixing agent. A polystyrene sulfonic acid 1 mg / L aqueous solution having a weight average molecular weight of 1,000,000 was passed as an aqueous solution every 20 hours, and the water treatment of the polyvinylamidine aqueous solution and the polystyrene sulfonic acid aqueous solution was repeated three times alternately. RO flux and IPA rejection were calculated in the same manner as in Example 1 except that rinsing with ultrapure water to which ₂ was added to 2000 mg / L was performed for 0.5 hour.

[Example 4]:
Except that polyethylene glycol having a weight average molecular weight of 6000 was used as the polyethylene glycol which is a raw material of the improving agent at the blocking rate in Example 1, the RO device flux and the IPA blocking rate were calculated in the same manner as in Example 1.

[Example 5]:
In the treatment with a polyvinylamidine 1 mg / L aqueous solution having a weight average molecular weight of 3 million as the first fixing agent aqueous solution and a polystyrene sulfonic acid 1 mg / L aqueous solution having a weight average molecular weight of 1,000,000 as the second fixing agent aqueous solution in Example 3. The RO device flux and IPA rejection were calculated in the same manner as in Example 3 except that NaCl was added to each aqueous solution as an electrolyte so that the concentration was 2000 mg / L.

[Example 6]:
Except that polyethylene glycol having a weight average molecular weight of 6000 was used as the blocking rate improver in Example 1, the same procedure as in Example 1 was performed to calculate the flux of the RO device and the IPA blocking rate.

[Comparative Example 1]:
The membrane to be filled in the RO device is a new membrane module made of Nitto Denko Corporation's ultra-low pressure aromatic polyamide RO membrane “ES20”, and this membrane is not subjected to the blocking rate improvement treatment and the immobilization treatment. The aforementioned IPA solution was passed under the same conditions as in Example 1, and the flux of the RO device and the IPA rejection rate were calculated.

[Comparative Example 2]:
In Example 1, except that the modification treatment with a blocking rate improver without adding an electrolyte was performed, the RO device flux and the IPA blocking rate were calculated in the same manner as in Example 1.

[Comparative Example 3]:
In Example 6, except that a modification treatment with a blocking rate improver without adding an electrolyte was performed, the RO device flux and the IPA blocking rate were calculated in the same manner as in Example 6.

  Table 1 shows the IPA removal rates and fluxes measured after 100 hours have elapsed from the start of water passage in Examples 1 to 6 and Comparative Examples 1 to 3, after 5000 hours have elapsed, and after 10,000 hours have elapsed. The progress of the rejection rate is shown in FIG. From these results, it can be seen that the effect of improving the rejection rate of Examples 1 to 6 is higher than that of Comparative Examples 1 to 3, and lasts for a long time.

[Examples 7 to 10, Comparative Examples 4 to 6]:
In Example 1, except that the electrolyte and concentration added to the rejection rate improver were changed as shown in Table 2, it was performed in the same manner as in Example 1, and after 100 hours passed from the start of water flow, the flux of the RO device and the IPA rejection rate The results of calculating are shown in Table 2. The results of Examples 1-2 and Comparative Example 2 are also shown.
From the results shown in Table 2, Examples 1-2 and 5-8, in which the electrolyte concentration was 1000 or more, particularly Examples 1-2, 6-8, and 500 mg / L or less compared to 2000 mg / L or less It can be seen that a much higher rejection rate improvement effect is obtained than in Examples 2 to 5.

  From the above results, as shown in the examples, by setting the concentration of the electrolyte to 1000 to 10000 mg / L, particularly 2000 to 5000 mg / L, compared with the comparative example used as a conventional tracer substance at 500 mg / L or less. It can be seen that a much higher rejection rate improvement effect can be obtained, and an unexpected effect can be obtained.

  INDUSTRIAL APPLICABILITY The present invention is used for a method for improving the rejection rate of a permeable membrane such as a reverse osmosis membrane or a nanofiltration membrane, a permeable membrane with an improved rejection rate, a permeable membrane treatment method using the same, and a permeable membrane device suitable for them. Is possible.

It is a flowchart which shows the permeable membrane processing method and apparatus by one Embodiment of this invention. It is a flowchart which shows the permeable membrane processing method and apparatus by another embodiment of this invention. It is a graph which shows the result of the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 RO membrane module 2 RO membrane 3 Primary side 4 Secondary side 11 To-be-treated water tank 12 Treated water tank 13 Alkaline cleaning liquid tank 14 Acidic cleaning liquid tank 15 Rejection rate improver aqueous solution tank 16 1st fixing agent aqueous solution tank 17 2nd Fixing agent aqueous solution tank 18 Electrolyte solution tank

Claims (11)

A method for improving the rejection rate of a permeable membrane, comprising: contacting a permeable membrane with a rejection rate improving agent to which an electrolyte is added so as to have a concentration of 1000 to 10000 mg / L. After performing the blocking rate improver treatment for improving the blocking rate of the permeable membrane by bringing the blocking rate improving agent added with an electrolyte so that the concentration becomes 1000 to 10000 mg / L into contact with the permeable membrane,
A first immobilizing agent containing a polymer having a weight average molecular weight larger than that of the blocking rate improver and a weight average molecular weight larger than that of the blocking rate improving agent, The method for improving the rejection of a permeable membrane according to claim 1, wherein the immobilization agent treatment is performed by alternately contacting a second immobilization agent containing an ionic polymer different from the immobilization agent at least once.   The method according to claim 1 or 2, wherein the rejection improving agent is cationic or anionic.   The method according to any one of claims 1 to 3, wherein the rejection rate improver is a compound having a polyalkylene glycol chain.   When the rejection improving agent is cationic, the first fixing agent is anionic, the second fixing agent is cationic, and when the rejection improving agent is anionic, the first fixing agent is cationic. The method according to any one of claims 2 to 4, wherein the second fixing agent is anionic.   The method according to any one of claims 2 to 5, wherein the rejection rate improving agent, the first fixing agent and the second fixing agent are each added with an electrolyte.   The method according to claim 1, wherein the electrolyte is selected from sodium chloride, calcium chloride, sodium sulfate and magnesium sulfate.   A permeable membrane obtained by the method according to claim 1.   A permeable membrane treatment method for performing a permeable membrane treatment by allowing a liquid to be treated to permeate a permeable membrane obtained by the method according to claim 1.   A permeable membrane treatment apparatus that uses the permeable membrane obtained by the method according to claim 1 and performs a permeable membrane treatment by allowing a liquid to be treated to permeate the permeable membrane. A permeable membrane module for passing the liquid to be treated to the primary side and taking out the permeate from the secondary side;
A rejection rate improver treatment apparatus for performing a rejection rate improver treatment by passing a rejection rate improver mainly composed of an organic substance through the primary side of the module;
An electrolyte addition device for adding an electrolyte to the rejection rate improver so as to have a concentration of 1000 to 10000 mg / L;
On the primary side of the module, a first immobilizing agent containing a polymer having a weight average molecular weight larger than that of the blocking rate improver, and a first immobilizing agent having a weight average molecular weight larger than that of the blocking rate improving agent, A permeable membrane device comprising: a second fixing agent containing different ionic polymers, and an immobilizing agent treatment device that performs the immobilizing agent treatment by alternately passing one or more times.

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