JP2010104919A - Method for improving rejection of permeable membrane, permeable membrane improving rejection, and method and device of treating permeable membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method and a device of improving the rejection of a permeable membrane capable of obtaining a high quality of treated water by increasing rejection improvement effect on an electrolyte containing nonionic substances such organic substances and weak electrolytes such as silica and keeping rejection improvement effect high to perform stable treatment over a long period of time while minimizing deterioration in permeation flux. <P>SOLUTION: The system is configured such that after modifier treatment where a first modifier 15 containing a cation or anion macromolecule is added and affixed to a primary side 3 of a permeable membrane module 1, and a second modifier 16 containing an ionic macromolecule different from the first modifier is further added and affixed is performed alternately once or more, a rejection improver 15 containing a compound having a polyalkylene glycol chain is supplied and affixed to the permeable membrane 2, thereby improving the rejection of the permeable membrane 2. <P>COPYRIGHT: (C)2010,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.

  Since the reverse osmosis membrane treatment apparatus has been developed as a desalination apparatus, conventionally, the rejection rate with respect to an electrolyte containing a strong electrolyte such as sodium chloride has attracted attention, and it has been studied to improve the rejection rate with respect to the electrolyte. Since then, reverse osmosis membrane treatment devices have come to be used as pure water production devices in ultrapure water production systems. However, ultrapure water production systems are not only common electrolytes including strong electrolytes, but also low molecular weight organic substances. Such nonionic substances and components of weak electrolytes such as silica and boron are concerned about the influence on the device, and it is required to obtain ultrapure water from which these are eliminated as much as possible.

  Patent Document 1 (Japanese Patent Laid-Open No. 2007-289922) proposes to treat a reverse osmosis membrane with a blocking rate improver even in such an ultrapure water production system. It has been shown that a reverse osmosis membrane is treated with a polyalkylene glycol having an average molecular weight of 2000 to 6000, or a blocking rate improver containing an ionic polymer having an anionic functional group introduced thereto. Such a blocking rate improver having a polyalkylene glycol chain can be expected to improve the blocking rate for nonionic substances such as organic substances, but it has been shown that the decrease in permeation flux is relatively large.

  Patent Document 2 (Japanese Patent Laid-Open No. 2006-110520) discloses a blocking 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. Rate improvers are shown. 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. However, Patent Document 2 shows that it is excellent in improving the rejection rate for electrolytes such as sodium chloride, but does not show improvement in the rejection rate for nonionic substances such as organic substances and weak electrolytes such as silica.

  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.

However, none of them has achieved satisfactory performance in terms of improving the rejection rate against nonionic substances such as organic substances and weak electrolytes such as silica. In Patent Document 3 (Japanese Patent Application Laid-Open No. 2008-246448), after treatment with a blocking rate improver having a polyalkylene glycol chain, treatment is carried out using a treating agent containing an ionic polymer as a modifying agent. Attempts have also been made to maintain the effect of the rate improver high over a long period of time, but this has not been sufficient to improve the rejection rate of the organic substances and silica.
JP 2007-289922 A JP 2006-110520 A JP 2008-246448

  An object of the present invention is to solve the conventional problems as described above with respect to an electrolyte including a nonionic substance such as an organic substance and a weak electrolyte such as silica while minimizing a decrease in permeation flux. A method for improving the rejection rate of a permeable membrane capable of obtaining a high quality of treated water by increasing the rejection rate improvement effect, maintaining a high rejection rate improvement effect, and capable of stable treatment over a long period of time, and a rejection rate A permeable membrane processing method using an improved permeable membrane, and a permeable membrane device suitable for these methods.

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) The permeable membrane is brought into contact with a first modifier containing an ionic polymer selected from cationic or anionic polymers, and then a ionic polymer different from the first modifier is added. After performing the modifying agent treatment to be brought into contact with the modifying agent 2 at least once,
A method for improving the rejection rate of a permeable membrane, comprising performing a treatment for improving the rejection rate by contacting with a rejection rate improving agent containing a compound having a polyalkylene glycol chain.
(2) The method according to (1) above, wherein the compound having a polyalkylene glycol chain is a nonionic compound.
(3) The method according to (1) or (2) above, wherein the compound having a polyalkylene glycol chain is polyalkylene glycol or a derivative thereof.
(4) The method according to any one of (1) to (3) above, wherein the first modifier is cationic and the second modifier is anionic.
(5) A permeable membrane obtained by the method according to any one of (1) to (4) above.
(6) 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 any one of (1) to (4) above.
(7) A permeable membrane treatment apparatus that performs permeable membrane treatment by using a permeable membrane obtained by the method according to any one of (1) to (4) above, and allowing a liquid to be treated to permeate the permeable membrane.
(8) a permeable membrane module for passing the liquid to be treated on the primary side and taking out the permeate from the secondary side;
The first modifier containing an ionic polymer and the second modifier containing an ionic polymer different from the first modifier are alternately passed through the primary side of the module one or more times. A modifier treatment apparatus for performing the modifier treatment,
A permeation membrane apparatus comprising: a rejection rate improver treatment apparatus for performing a rejection rate improver treatment by passing a rejection rate improver containing a compound having a polyalkylene glycol chain.

  In the present invention, the permeation membrane to be treated with the rejection rate improving agent 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 reverse osmosis 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 treatment for improving the rejection rate according to the present invention can be suitably applied to aromatic polyamide permeable membranes, particularly RO membranes. The permeable membrane to be treated with such a blocking rate improver may be an unused permeable membrane or a permeable membrane whose performance is reduced by use.

  The modifying agent treatment and the rejection rate improving agent treatment in the present invention are performed on a permeable membrane in a state where such a permeable membrane is mounted on a module of a membrane separation apparatus or not mounted on a 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.

  When performing the treatment for improving the rejection rate of the present invention, in the case of an unused permeable membrane, or in the case of a permeable membrane whose performance has deteriorated due to use, a permeable membrane that has been subjected to chemical cleaning may be targeted for treatment with a modifier. However, in the case of a permeable membrane whose performance has deteriorated due to use, those subjected to chemical cleaning are preferred. The purpose of chemical cleaning is to facilitate the adsorption of the modifier to 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 the module or immersing the permeable membrane in the chemicals. .

  In the treatment with the modifier in the present invention, the permeation membrane to be treated is brought into contact with a first modifier containing an ionic polymer selected from cationic or anionic polymers, and then the first modifier and Is a treatment in which the modifier treatment for contacting with the second modifier containing different ionic polymers is performed one or more times.

  The modifying agent that can be used as the first and second modifying agents has a weight average molecular weight of 10,000 to 10,000,000, preferably 100,000 to 10,000,000, more preferably 300,000 to It is an ionic polymer selected from water-soluble cationic or anionic polymers of 5,000,000, more preferably 1,000,000 to 5,000,000. As the ionic polymer, either the cationic polymer or the anionic polymer is used as the first modifier, and the ionic polymer opposite to the first polymer is used as the second modifier. These modifiers are alternately contacted one or more times to perform the modifier treatment.

  Examples of the cationic polymer used in the modifier 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; secondary amines such as polyethyleneimine. Compound; Tertiary amine compound such as poly (dimethylaminoethyl acrylate) and poly (dimethylaminoethyl methacrylate); the above tertiary amine compound treated with a quaternizing agent such as methyl chloride, quaternary ammonium on polystyrene And quaternary ammonium compounds such as those having a group added; compounds having a heterocyclic ring such as polyvinylamidine, polyvinylpyridine, 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 [1]. However, in General Formula [1], R ^{1 to} R ⁴ are hydrogen or an alkyl group such as a methyl group.

  The cationic polymer having the structural unit represented by the general formula [1] 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 [1], the polyvinylamidine produced by such a method includes a cyano group derived from acrylonitrile, a carbamoyl group formed 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 modifier 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 sulfate, and polyvinyl sulfonic acid. Examples thereof include polymers, and copolymers 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 modifier of the present invention can be used as a salt having a counter ion in both cases of the cationic modifier and the anionic modifier. Examples of the salt having a counter ion include polyvinylamidine hydrochloride, polyacrylic acid sodium salt, and polystyrenesulfonic acid sodium salt.

  These modifiers 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. The treatment liquid containing the modifier 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 modifier varies depending on the type of the compound used. For example, in the case of a cationic polymer or anionic polymer having a weight average molecular weight of 100,000 or more, 0.1 to 50 mg / L is preferable. If the concentration is lower than this, it may take a long time to process the modifier. 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.

  The modifier treatment includes a first modification treatment in which a first modifier containing an ionic polymer is brought into contact with a permeable membrane to be treated, and an ionic polymer different from the first modifier. The second modification treatment with which the second modifier is brought into contact is alternately performed once or more. In the modifier treatment, the modifier treatment can be performed by passing the modifier. In this case, it is preferably carried out by passing a treatment liquid containing a modifier on the primary side of the module. At this time, the operation pressure at the time of supplying the aqueous solution containing the modifier to the primary side of the permeable membrane module is 0.3 MPa or more, and the supply amount of the aqueous solution containing the permeated water amount / rejection rate improver is 0.2 or more It is preferable to do. There is no limit to the number of times the treatment is alternately performed with the cationic modifier and the anionic modifier, and the treatment can be alternately repeated as necessary.

  It is preferable to use the one containing a cationic polymer as the first modifier and the one containing an anionic polymer as the second modifier and alternately treating with the opposite ionic polymer. But you can. In the treatment of a polyamide-based permeable membrane with a modifier, the first modifier is firmly bound to the membrane surface from the aspect of affinity and held by treating with a cationic modifier as the first modifier. Is possible. Then, the stability is further improved by treating with an anionic modifier as the second modifier. Thereafter, the stability can be improved by alternately treating with a cationic modifier and an anionic modifier. In particular, by using polyvinylamidine as the cationic polymer and polystyrene sulfonic acid as the anionic polymer, the adsorption layer can be stabilized and the effect of improving the electrolyte rejection can be maintained.

  In the present invention, the first modifier containing an ionic polymer and the second modifier containing an ionic polymer different from the first modifier are alternately contacted one or more times for modification. After performing the agent treatment, a blocking rate improver treatment for improving the blocking rate of the permeable membrane is performed by bringing a blocking rate improving agent containing a compound having a polyalkylene glycol chain into contact with the permeable membrane. As the compound having a polyalkylene glycol chain, a nonionic compound is preferable.

  An adsorption layer made of an ionic polymer is effective in improving the blocking rate of the electrolyte, but the effect of improving the blocking rate of the water-soluble low-molecular-weight organic substance is small. This is presumably because low molecular weight organic substances pass through the gaps between the adsorption layers of ionic polymers. Therefore, it is presumed that the blocking rate of the low-molecular-weight organic substance can be effectively improved by supplementing the gap between the adsorption layers of the ionic polymer with the following blocking rate improver. In this case, if the polymer used to supplement the gap is charged, it will be adsorbed to any of the ionic polymers, and it is difficult to achieve the purpose of complementing the gap. Highly polar, non-charged, non-ionic compound with polyalkylene glycol chain, which is a water-soluble polymer compound, can be used to improve the blocking rate of low molecular weight organic compounds. Can be improved.

  The blocking rate improving treatment agent of the present invention is a blocking rate improving agent containing a compound having a polyalkylene glycol chain, as long as the blocking rate of soluble substances such as water-soluble organic substances and inorganic electrolytes by the permeable membrane is improved. It can be used without particular limitation. The compound having a polyalkylene glycol chain used as a blocking rate improver is a water-soluble polymer compound having a polyalkylene glycol chain and is preferably a nonionic polymer, but may be an ionic polymer. Good. By using these compounds as a blocking rate improver, the blocking rate of permeable membranes that have been treated with modifiers is improved, and low molecular weights that have been difficult to remove by conventional processing, including general electrolytes including strong electrolytes. It is also possible to effectively remove nonionic substances such as organic substances and weak electrolytes such as silica and boron.

  As the usable blocking rate improver, known compounds having a polyalkylene glycol chain can be used, and those described in Patent Documents 1 and 2 as well as those having other blocking rate improving ability are used. it can. Examples of the blocking rate improver that can be used include compounds having a polyethylene glycol chain described in Patent Document 1. Examples of such a compound having a polyalkylene glycol chain include polyethylene glycol or polyethylene glycol derivatives.

  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, the compound having a polyalkylene glycol chain is a polyalkylene glycol having a hydroxyl group at the end of the polyalkylene glycol chain, a nonionic group by esterification or etherification at the end, preferably 8 or more carbon atoms. It is preferable to use a compound having a hydrophobic group, particularly an alkyl group having 8 to 20 carbon atoms or a hydrophobic group composed of an alkylene group, that is, a nonionic surfactant alone or in combination. When used in combination, they may be mixed and processed, or may be processed before and after.

  Examples of the nonionic surfactant include polyoxyethylene alkyl (or alkenyl) ether, polyoxyethylene alkyl (or alkenyl) phenyl ether, alkyl (or alkenyl) glucoside, polyoxyethylene sorbitan fatty acid ester and the like.

  In the present invention, the weight average molecular weight of the compound having a polyalkylene glycol chain is not particularly limited. However, when the terminal of the polyalkylene glycol chain is a hydroxyl group, the weight average molecular weight of the polyalkylene glycol is preferably 1,000 to 10. 1,000, more preferably 2,000 to 6,000, and still more preferably 3,000 to 5,000. Moreover, when it becomes nonionic by esterification, etherification, etc. at the terminal, the weight average molecular weight of the nonionic surfactant is preferably 400 to 3,000, more preferably 500 to 2,000, still more preferably. 600 to 1,500.

  These blocking rate improvers are selected according to the material, form, etc. of the permeable membrane to be treated, the types of the first and second modifiers, the treatment conditions, etc. Used by dissolving in a solvent such as treated water. The concentration of the blocking rate improving agent varies depending on the permeable membrane, the type of the module, etc., but is generally adjusted to a concentration of 0.01 to 5 mg / L and used for the blocking rate improving process. Since the compound having a polyalkylene glycol chain as a blocking rate improver has a greater effect of lowering the permeation flux than the ionic polymer of the first or second modifier, a decrease in permeation flow rate is caused by increasing the addition amount. Since it becomes large and impractical, the concentration of the compound having a polyalkylene glycol chain of the blocking rate improver is about 1/3 to 1/20 of the concentration of the ionic polymer of the first or second modifier. It is preferable to use it at a concentration. For example, when the concentration of the ionic polymer is 10 mg / L, the concentration of the compound having a polyalkylene glycol chain is preferably about 2 mg / L. 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 rejection rate improving process using the rejection rate improving agent, the rejection rate improving agent is supplied and brought into contact with the permeable membrane of the processing target module that has been subjected to the modifier treatment, thereby improving the rejection rate of the permeable membrane. In this case, the 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. In this case, the operation pressure at the time of supplying the aqueous solution containing the rejection rate improving agent to the primary side of the module is 0.3 MPa or more, and the supply amount of the aqueous solution containing the permeated water amount / rejection rate improving agent is 0.2 or more. It is preferable to do. 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 rejection rate improving agent 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 set to 0.3 MPa or more, and the ratio of the amount of permeate / the amount of aqueous solution containing the rejection improving agent is 0. Two or more are 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 modifier treatment and the rejection improving agent treatment, the amount of the polymer adsorbed on the permeable membrane is generally about 0.005 to 0.05 mg / m ² , although it varies depending on the type of polymer. Therefore, depending on the number of permeable membrane modules to be processed, taking into consideration the amount of polymer that decreases due to adsorption to the permeable membrane, additional polymer is added to make the total polymer adsorption even. It is preferable to do.

  In the present invention, when the permeable membrane is treated with a modifier and a rejection rate improving agent, the effect of improving the rejection rate after the treatment can be improved by adding an electrolyte as a charge neutralizing substance to each treatment solution. The modifiers having ionicity repel each other due to their ionicity, and when they cannot be modified precisely, an electrolyte is added to neutralize the charge of the blocking rate improver and suppress the repulsion. Thus, the modification can be performed more precisely than the additive-free state. As the electrolyte, salts such as sodium chloride, calcium chloride, magnesium sulfate, and sodium sulfate can be used, but the electrolyte is not limited thereto. The electrolyte concentration to be added is preferably 100 to 5000 mg / L. When the electrolyte concentration is low, the effect of improving the rejection is not observed, and when the electrolyte concentration is high, the polymer aggregates and cannot be modified precisely. When the electrolyte is added, it may be added only when the modifier is treated, or the subsequent inhibition rate improver treatment may be continuously added.

  The modifier and the rejection rate improver used in the present invention can each contain a rejection rate confirmation tracer material such as an inorganic electrolyte and a water-soluble organic compound. By passing water containing a tracer substance together with a compound that is the main component of a modifier or a blocking rate improver, the blocking rate of the permeable membrane is confirmed over time by passing it through a permeable membrane such as a nanofiltration membrane or reverse osmosis membrane. Thus, it is possible to determine whether to continue or stop the process. 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 rejection rate improver treatment or the modifier treatment can be terminated.

  According to this method, the contact time between the aqueous solution of the modifier or the rejection rate improving 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. . In addition, when a plurality of treatments with a different blocking rate improver or a modifying agent is performed using a different blocking rate improver or a blocking agent, a plurality of times of processing can be efficiently performed without losing the switching timing. .

Examples of the water-soluble organic compound used as the tracer substance include isopropyl alcohol, glucose, urea, and the like, but isopropyl alcohol is preferable because of ease of handling. Examples of the inorganic electrolyte used as the tracer substance include sodium chloride, sodium nitrate, and weak electrolyte boric acid. However, when the electrolyte is added to increase the inhibition rate improvement effect, it is not possible to easily determine the end of the treatment based on the conductivity. Therefore, a water-soluble organic compound is preferably used as the tracer substance.
The concentration of the tracer substance is preferably 1 to 500 mg / L, more preferably 10 to 100 mg / L in the case of an inorganic strong electrolyte such as sodium chloride. In the case of other inorganic weak electrolytes such as boric acid and water-soluble organic substances such as isopropyl alcohol, it is preferably 1 to 5000 mg / L, more preferably 5 to 1000 mg / L.

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 modifier treatment and the blocking rate improving agent treatment, 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, has a high effect of improving the rejection rate of the permeable membrane by the treatment with the modifier and the rejection rate improver, and maintains the high state for a long time be able to.

  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 through the permeable membrane obtained by the above-described inhibition rate improving method. The effect of improving the blocking rate of the permeable membrane is high, and the high state can be maintained for a long time, the organic matter removing effect is high, and stable treatment is possible for 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 allowing the liquid to permeate, the effect of improving the blocking rate of the permeable membrane by the modifier treatment and the blocking rate improving agent treatment is high, and the high state can be maintained for a long time, and the organic matter removing effect is achieved. High and stable treatment is possible over a long period of time.

  A preferred permeable membrane processing 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 a permeable polymer module containing an ionic polymer on the primary side of the module. A modifier treatment apparatus for performing a modifier treatment by alternately passing one modifier and a second modifier containing an ionic polymer different from the first modifier one or more times, and a polyalkylene It is a permeable membrane apparatus including a blocking rate improver treatment apparatus that performs blocking rate improving agent treatment by passing a blocking rate improving agent containing a compound having a glycol chain.

  In the above permeable membrane processing apparatus, the liquid to be processed is passed through the primary side of the permeable membrane module, the permeated liquid is taken out from the secondary side, and the permeable membrane treatment is performed. The first modifier containing an ionic polymer and the second modifier containing an ionic polymer different from the first modifier are alternately passed one or more times for treatment with the modifier. The blocking rate of the permeable membrane is carried out by passing a blocking rate improving agent containing a compound having a polyalkylene glycol chain to the primary side of the module by the blocking rate improving agent treatment apparatus and performing the blocking rate improving agent treatment. Can be improved.

  The water to be treated as the treatment target by the permeation membrane with improved rejection rate and the permeable membrane treatment method and apparatus of the present invention is not particularly limited, but can be suitably used for electrolyte and organic substance-containing water, for example, electrical conductivity. (EC) = 1-500 mS / m, TOC = 0.01-100 mg / L, preferably (EC) = 5-100 mS / m, TOC = 0.1-30 mg / L Is preferably used. As such electrolyte and organic substance-containing water, general industrial water, well water, electronic device manufacturing factory effluent, transportation machine manufacturing factory effluent, organic synthesis factory effluent or printing plate making / painting factory effluent, etc. Can be mentioned.

  The permeable membrane treatment apparatus and the permeable membrane treatment method of the present invention have an activated carbon tower, a coagulation sedimentation apparatus, a coagulation pressure flotation apparatus, a filtration apparatus or a decarboxylation as a pretreatment apparatus for the purpose of preventing clogging or fouling of the RO apparatus. An apparatus is preferably provided. As the filtration device, a sand filtration device, an ultrafiltration device, a microfiltration device, a small filtration device, or the like can be used. A prefilter may be further provided as a pretreatment device. Further, since the RO membrane is susceptible to oxidative degradation, it is preferable to provide a device for removing the oxidant (oxidation degradation inducing substance) contained in the raw water as necessary. As an apparatus for removing such an oxidative degradation inducing substance, an activated carbon tower, a reducing agent injection apparatus, or the like can be used. In particular, the activated carbon tower can also remove organic substances and can also be used as a fouling prevention means as described above. The pH of the raw water is not particularly limited.

  Moreover, it is preferable to provide a water quality meter after the RO device for the purpose of monitoring that the RO treatment is properly performed. As the water quality meter, an electrolyte in permeated water, a conductivity meter (non-resistance meter) for measuring the organic substance concentration, and a TOC meter can be suitably used. As the TOC meter, a wet oxidation TOC measuring device capable of online measurement in a range of TOC concentration of 0.001 to 10 mg / L can be used. By providing such a conductivity meter and a TOC meter, it is possible to monitor a decrease in the rejection rate due to the deterioration of the RO membrane, and the RO membrane can be replaced as appropriate.

  The RO device may be used in one stage, or may be provided in two or more stages to improve water quality. In addition, when the RO device is provided in multiple stages, an RO membrane treated with a blocking rate improver described later may be used for all RO devices or only for a specific stage.

  When ultrapure water is produced by the water treatment apparatus and the water treatment method of the present invention, a decarbonation means, an ion exchange device, an electric regeneration deionization device, a UV oxidation device, a mix are provided after the water quality meter. A resin device, an ultrafiltration device, or the like can be provided.

  According to the present invention, the modification is made such that the permeable membrane is brought into contact with a first modifier containing an ionic polymer and then brought into contact with a second modifier containing an ionic polymer different from the first modifier. After the agent treatment is performed once or more, the organic matter can be obtained while minimizing the decrease in the permeation flux by contacting with the rejection rate improver containing the compound having a polyalkylene glycol chain and performing the rejection rate improver treatment. It is possible to increase the rejection rate improvement effect for non-ionic substances such as silica and electrolytes including weak electrolytes such as silica to obtain a high quality of treated water, while maintaining the rejection rate improvement effect in a high state, Stable treatment is possible over a 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 first modifying agent aqueous solution tank, 16 is a second modifying agent aqueous solution tank, and 17 is a blocking rate improving agent aqueous solution. Tank, 18 is an electrolyte solution tank, P1 is a high pressure pump, P2 is a cleaning liquid pump, P3 is a first modifier aqueous solution pump, P4 is a second modifier aqueous solution pump, P5 is a blocking rate improver 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 permeate is sent to the alkaline cleaning liquid tank 13, the acidic cleaning liquid tank 14, the first modifier aqueous solution tank 15, the second modifier aqueous solution tank 16, and the rejection rate improving agent aqueous solution tank 17. And can be used for dilution, adjustment, etc. of the cleaning liquid or the aqueous polymer 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 fixed time, and then the drain pipe (not shown) provided with the alkaline cleaning liquid in the alkaline cleaning liquid tank 13 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 acid 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, in the case where the modifier treatment and the rejection rate improver treatment are performed using two types of modifiers and the rejection rate improver, a cationic polymer polyvinylamidine aqueous solution as a first modifier is added to the first modifier aqueous solution tank 15. The second modifier aqueous solution tank 16 is filled with an anionic polymer polystyrene sulfonic acid aqueous solution, and the blocking rate improver aqueous solution tank 17 is filled with an aqueous solution of a compound having a polyethylene glycol chain (hereinafter referred to as “PEG”) as a blocking rate improver, First, the valves V2, V4, V23, V33 are opened, the other valves are closed, the cleaning pump P2 is operated, and the cationic polymer polyvinylamidine aqueous solution in the first modifier aqueous solution tank 15 is supplied to the RO membrane module 1. After being introduced into the secondary side 3, it is circulated so as to return to the first modifier aqueous solution tank 15 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 valve V6 and V14 may be opened and the membrane-permeated cationic polymer aqueous solution may be used as the first modifier aqueous solution. It is preferable to return to the tank 15. After the cationic polymer aqueous solution is circulated for a predetermined time, the cationic polymer aqueous solution is discharged out of the system from a drain pipe (not shown) provided in the first modifier aqueous solution tank 15.

  Next, the valves V2, V4, V24, V34 were opened, and the other valves were closed, and the anionic polymer polystyrene sulfonic acid aqueous solution in the second modifier aqueous solution tank 16 was introduced into the primary side 3 of the RO membrane module 1. Then, it is circulated so as to return to the second modifier aqueous solution tank 16 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, but the valves V6 and V15 may be opened to pass the membrane-permeable anionic polymer aqueous solution to the second modifier tank. It is preferable to return to 16. After circulating the anionic polymer aqueous solution 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 modifier aqueous solution tank 16.

  Next, the valves V2, V4, V25, and V35 are opened, and the other valves are closed. After introducing the aqueous PEG solution in the rejection rate improving agent aqueous solution tank 17 to the primary side 3 of the RO membrane module 1, the rejection rate is improved again. Circulate so as to return to the agent tank 17. 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 pass the membrane-penetrated PEG aqueous solution to the rejection rate improver tank 17. It is preferable to return to the inside. 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 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 the modifying agent treatment or the rejection rate improving agent treatment is performed while the electrolyte is added, the electrolyte solution pump P6 is operated to open the valve V16 so that the electrolyte solution from the electrolyte solution tank 18 has a predetermined concentration. The treatment is carried out by adding to the blocking rate improver, the first modifier or the second modifier. Washing (rinsing) with the treatment water or the electrolyte-added treatment water is preferably performed between the treatment with the inhibition rate improver, the treatment with the cationic modifier aqueous solution, and the treatment with the anionic modifier aqueous solution.

  Fig. 2 shows that RO treatment is performed by passing the water to be treated, and the first modifier or the second modifier is added to the water to be treated, and then the modifier treatment is performed. The example which performs a rate improvement agent process is shown. In FIG. 2, when the modifier treatment and the blocking rate improver treatment are performed using a cationic polymer, an anionic polymer, and PEG, for example, a first modifier aqueous solution tank 15 and a second modifier aqueous solution tank 16 are used. The blocking rate improver aqueous solution tank 17 is filled with a cationic polymer aqueous solution, an anionic polymer aqueous solution, and a PEG aqueous solution, respectively.

  To perform the modifier treatment, first, the valve V33 is opened, the pump P3 is operated, the cationic polymer aqueous solution in the first modifier aqueous solution tank 15 is introduced into the water tank 11 to be treated, and then the high-pressure pump P1 is turned on. After the operation, the valves V1, V2, V4, V9 are opened, the other valves are closed, 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 the tank is again 11 to circulate back. At this time, it is preferable that the valves V3 and V5 are opened to allow a part of the cationic 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 V33 is closed and the pump P3 is stopped to stop the introduction of the cationic polymer aqueous solution.

  Next, the valve V34 is opened and the pump P4 is operated, the anionic polymer aqueous solution in the second modifier aqueous solution tank 16 is introduced into the water tank 11 to be treated, and then the high-pressure pump P1 is operated to operate the valves V1, V2, V4. , V9 is opened, the other valves are closed, and the aqueous anionic polymer solution in the treated water tank 11 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 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 aqueous anionic polymer solution for a predetermined time, the valve V34 is closed and the pump P4 is stopped to stop the introduction of the aqueous anionic polymer solution.

  Next, the valve V35 is opened, the pump P5 is operated, the aqueous PEG solution in the rejection rate improving agent aqueous solution tank 17 is introduced into the water tank 11 to be treated, and then the high-pressure pump P1 is operated to operate the valves V1, V2, V4, V9. The other PEG is closed and the PEG 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 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 V35 is closed and the pump P5 is stopped to stop the introduction of the PEG 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. When the rejection rate improver treatment, the modifier treatment or the washing is performed while the electrolyte is added, the electrolyte solution pump P6 is operated and the valve V16 is opened to bring the electrolyte solution from the electrolyte solution tank 18 to a predetermined concentration. In this way, the rejection rate improver treatment, modifier treatment or washing is carried out while adding to the treated water.

  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 modifier may be performed twice or more alternately with the cationic polymer aqueous solution and the anionic polymer aqueous solution, but the treatment with the anionic polymer aqueous solution is preferred at the end.

  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 rejection rate 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 separately prepared vessel at the destination for chemical cleaning. You may implement a process process, a rejection rate improvement process process, etc.

  Further, in the case of FIG. 2, the modifier or the rejection rate improving agent aqueous solution is supplied to the treated water tank 11, and these modifications are connected to the pipe connecting the treated water tank 11 and the RO membrane module 1. Alternatively, the agent or the blocking ratio improver aqueous solution may be directly line-injected. 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, a mineral acid such as hydrochloric acid, sulfuric acid or nitric acid, or an organic acid such as citric acid or 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 and a comparative example are given and this invention is demonstrated further in detail, this invention is not limited at all by the following examples.
The permeable membrane module used in this example and the comparative example is a 4-inch new membrane module of ultra-low pressure aromatic polyamide RO membrane “ES-20” manufactured by Nitto Denko Corporation. Both concentrated water and permeable water are supplied. Membrane separation was carried out by total circulation treatment returning to the tank, and the rejection rate improver treatment and the effect were evaluated.

In this example and the comparative example, the evaluation conditions are an evaluation water inlet pressure of 0.75 MPa and a brine water amount of 15 L / min.
The evaluation water used for the evaluation is as follows.
₍₁₎ silica-containing water 20mg-SiO 2 /L,pH6.5.
(2) 100 mg-IPA / L, pH 6.5 isopropanol-containing water.

In this example and comparative example, the rejection rate of silica and isopropanol (IPA) was calculated by the following formula.
Blocking rate (%) = [1- (solute permeate concentration × 2) / (solute supply solution concentration + solute concentration)] × 100

[Example 1]:
A 4-inch new membrane module of ultra-low pressure aromatic polyamide RO membrane “ES-20” manufactured by Nitto Denko Corporation, 10 mg / L of polyvinylamidine having a weight average molecular weight of 3 million at a pressure of 0.75 MPa, a brine water volume of 15 L / min. After passing the aqueous solution for 2 hours and rinsing the excess polymer with pure water, the polystyrene sulfonic acid 10 mg / L aqueous solution having a weight average molecular weight of 1,000,000 was passed for 2 hours to perform the modifier treatment, and the excess polymer was purified. After rinsing with water, a polyethylene glycol 2 mg / L aqueous solution having a weight average molecular weight of 3,000 was passed through for 1 hour to perform a blocking rate improver treatment, and rinsed with pure water.
Table 1 shows the results obtained by passing the evaluation water (1) and (2) through the obtained treatment module under the evaluation conditions and measuring the permeation flux, silica rejection and IPA rejection.

[Example 2]:
In Example 1, a polyethylene glycol 2 mg / L aqueous solution was passed through for 1 hour and rinsed with pure water, and then a polyoxyethylene (50) stearyl ether 0.5 mg / L aqueous solution was passed through for 15 minutes. The treatment and evaluation were performed in the same manner except for rinsing. The results are shown in Table 1.

[Example 3]:
In Example 1, the treatment and evaluation were similarly performed except that the polyoxyethylene (50) stearyl ether 0.5 mg / L aqueous solution was passed for 15 minutes instead of the treatment of passing the polyethylene glycol 2 mg / L aqueous solution for 1 hour. went. The results are shown in Table 1.

[Comparative Example 1]:
For the 4-inch new membrane module of the ultra-low pressure aromatic polyamide type RO membrane “ES-20” manufactured by Nitto Denko Corporation, the evaluation water (1) was obtained without performing the modifier treatment and the blocking rate improver treatment of the examples. Table 1 shows the results of measurement of permeation flux, silica rejection rate and IPA rejection rate by passing water under conditions (2) and (2).

[Comparative Example 2]:
In Example 1, a polyvinylamidine 10 mg / L aqueous solution was passed for 2 hours, the excess polymer was rinsed with pure water, and then a polystyrene sulfonic acid 10 mg / L aqueous solution was passed for 2 hours, and the excess polymer was passed with pure water. Table 1 shows the results of a similar evaluation performed with the modifier treatment for rinsing and the subsequent rejection rate improving agent treatment.

[Comparative Example 3]:
In Example 1, a polyethylene glycol 2 mg / L aqueous solution having a weight average molecular weight of 3,000 was passed for 1 hour without treatment with a modifier, treated with a blocking rate improver, rinsed with pure water, and similarly. Table 1 shows the results of the evaluation.

[Comparative Example 4]:
In Example 1, the modifier treatment and the rejection rate improver treatment are reversed, the polyethylene glycol 2 mg / L aqueous solution is passed through for 1 hour to perform the rejection rate improver treatment, rinsed with pure water, and then polyvinylamidine 10 mg / liter. The aqueous L solution was passed for 2 hours, the excess polymer was rinsed with pure water, and then the polystyrenesulfonic acid 10 mg / L aqueous solution was passed for 2 hours, followed by a modifier treatment for rinsing the excess polymer with pure water. Table 1 shows the results of the evaluation.

  From the results of Table 1, it can be seen that the blocking rate improvement effects of Examples 1 to 3 are higher than those of Comparative Examples 1 to 4, and the silica blocking rate and the IPA blocking rate are high. On the other hand, in Comparative Example 2 in which only the modifier treatment is performed and the subsequent rejection rate improving agent treatment is not performed, the silica rejection rate is relatively high, but the IPA rejection rate is low. In Comparative Example 3 in which only the rejection rate improver treatment was performed without the modifier treatment, the silica rejection rate was low and the IPA rejection rate was not greatly improved. In Comparative Example 3 in which the modifier treatment and the rejection improver treatment are reversed, the silica rejection is low, the IPA rejection is not significantly improved, and the first adsorbed polyethylene glycol is charged polymer. It is presumed to suppress the adsorption of.

  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.

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 1st modifier aqueous solution tank 16 2nd modifier aqueous solution tank 17 Improvement of rejection rate Aqueous solution tank 18 Electrolyte solution tank

Claims (8)

The permeable membrane is contacted with a first modifier containing an ionic polymer selected from cationic or anionic polymers, and then a second modification containing an ionic polymer different from the first modifier After one or more modifier treatments to contact the agent,
A method for improving the rejection rate of a permeable membrane, comprising performing a treatment for improving the rejection rate by contacting with a rejection rate improving agent containing a compound having a polyalkylene glycol chain.   The method according to claim 1, wherein the compound having a polyalkylene glycol chain is a nonionic compound.   The method according to claim 1 or 2, wherein the compound having a polyalkylene glycol chain is polyalkylene glycol or a derivative thereof.   The method according to claim 1, wherein the first modifier is cationic and the second modifier is anionic.   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;
The first modifier containing an ionic polymer and the second modifier containing an ionic polymer different from the first modifier are alternately passed through the primary side of the module one or more times. A modifier treatment apparatus for performing the modifier treatment,
A permeation membrane apparatus comprising: a rejection rate improver treatment apparatus for performing a rejection rate improver treatment by passing a rejection rate improver containing a compound having a polyalkylene glycol chain.

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