JP4872813B2 - Method for improving rejection rate of permeable membrane and permeable membrane treatment method - Google Patents

Description

The present invention provides a method for improving the rejection rate of a permeable membrane, which can improve the rejection rate in a state where the flux of a permeable membrane such as a reverse osmosis membrane and a nanofiltration membrane is increased, and maintain these improvement effects in a high state. those concerning the permeable membrane process how to use a transparent film with improved rejection.

  Permeation membranes used for water treatment, especially nanofiltration membranes, selective permeable membranes such as reverse osmosis membranes (RO membranes), such as the blocking rate and flux (permeation flux) for separation targets such as inorganic electrolytes and water-soluble organic substances The permeation characteristics deteriorate due to the influence of oxidizing substances and reducing substances present in the water and deterioration of the raw material polymer due to other causes, and the required treated water quality and quantity of treated water 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. Moreover, when organic substance containing water discharged | emitted from an electronic device manufacturing factory etc. is processed and collect | recovered using a reverse osmosis membrane apparatus, the flux fall by an organic substance pollutant becomes a problem. Even when industrial water or tap water is used as a water source, organic contamination may be a problem.

  In the ultrapure water production system as described above, it has been proposed to improve the rejection rate by treating the reverse osmosis membrane with a rejection 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 coacervate made from a methacrylate polymer, copolymer or terpolymer, a first polymer having a plurality of sulfonium or quaternary ammonium groups and a second polymer having a plurality of carboxylate groups, with any other substituents Branched 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. Yes. 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.

In the state before the permeation membrane is attached, or in the state where the permeation membrane is attached to the module, the conventional permeation rate improvement agent treatment is performed by supplying the above-described permeation rate improving agent and contacting the permeation membrane. The entire or part of the blocking rate improver is attached to the surface or the internal structural material of the permeable membrane by bonding, reaction or the like, and a modification treatment is performed to improve the blocking rate of the permeable membrane.

Patent Document 4 describes a method of improving the flux while keeping the desalination rate high by contacting a polyamide-based reverse osmosis membrane with an aqueous hydrogen peroxide solution and oxidizing it. Patent Document 5 describes a method for producing a composite reverse osmosis membrane having a high salt rejection and a high permeability by bringing sodium hypochlorite into contact with a polyamide-based reverse osmosis membrane and oxidizing it. ing.
Japanese Patent Application No. 2006-218471 Japanese Patent No. 2762358 JP 2006-110520 A JP 2005-103342 A JP 2000-334280 A

Wherein in rejection enhancing agent treatment of conventional permeable membrane using rejection enhancing agent such as those described in Patent Documents 1 to 3, it ends the modification process of the rejection enhancing agent, and passed through the water to be treated When the permeable membrane treatment is performed, the flux is lower than that at the end of the rejection rate improving agent treatment, and there is a problem that the permeable membrane treatment cannot be performed for a long period of time. In such a process, prior to the rejection enhancing agent treatment, acid, cleaning with an alkaline agent is often performed, a problem that such a cleaning process be performed not prevent the deterioration of flux there were.

  In addition, the conventional oxidation treatment as described in Patent Documents 4 to 5 cannot be expected to improve the rejection rate, and the improved flux rapidly decreases, and the permeable membrane treatment cannot be performed over a long period of time. There was a problem. In order to delay the decrease in flux after the oxidation treatment, it has also been proposed to impart hydrophilicity by reacting the oxidized membrane with a solution of a substance capable of a crosslinking reaction or a polymerization reaction such as glyoxal or epichlorohydrin. However, there is a problem that the effect of preventing the decrease in flux is small for the complicated processing.

In order to solve the conventional problems as described above, the problem of the present invention is to improve the rejection rate in a state where the flux of the permeable membrane is high, and to maintain these improvement effects in a high state. high organic matter removal effect is to provide a stable rejection enhancing method that can be processed permeable membrane, and the permeable membrane process how to use a transparent film with improved rejection over a long period of time.

The present invention is a rejection enhancing methods and permeable membrane treatment how the next permeable membrane.
(1) After performing an oxidation treatment by bringing an oxidant into contact with the permeable membrane,
It is a method for performing a blocking rate improver treatment for improving the blocking rate of a permeable membrane by bringing a blocking rate improving agent into contact with the permeable membrane ,
The oxidizing agent is selected from peroxides and chlorinating agents;
The method for improving the rejection of a permeable membrane, wherein the treatment for improving the rejection is a treatment in which a cationic polymer and an anionic polymer are contacted separately .
(2) 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 described in (1 ) above.

In the present invention, the permeation membrane to be subjected to the oxidation treatment and the rejection rate improving agent treatment is a permeation membrane that allows the liquid to be treated to pass through the primary side and permeates it, takes out the permeate from the secondary side, and performs membrane separation However, selective permeable membranes that separate inorganic electrolytes such as reverse osmosis membranes and nanofiltration membranes and water-soluble organic substances from water are particularly suitable. 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, it can be suitably applied aromatic polyamide permeable membrane, especially rejection enhancing agent treatment according to the present invention the RO membrane. 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 oxidation treatment and the rejection improving agent treatment in the present invention are performed on the permeable membrane in a state where such a permeable membrane is equipped in the module of the membrane separation apparatus or not in the module. There is no restriction | limiting in particular about the form of RO membrane module, For example, a tubular membrane module, a flat surface membrane module, a spiral membrane module, a hollow fiber membrane module etc. are applicable.

Oxidation treatment and rejection enhancing agent treatment, if the unused permeable membrane or with the case of the permeable membrane performance has been reduced by the use, to be subject to rejection enhancing agent treatment a permeable membrane subjected to chemical cleaning However, in the case of a permeable membrane whose performance has been reduced by use, a membrane subjected to chemical cleaning is preferred. The purpose of the chemical cleaning is to remove the contaminants on the surface of the film so that the blocking rate improver is easily adsorbed on the film itself. 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.), reducing agents, etc. In general, cleaning is performed by passing an aqueous solution of these chemicals through a module or immersing a permeable membrane in the chemicals.

  In the present invention, the oxidation treatment is performed by bringing an oxidant into contact with the permeable membrane before the treatment for improving the rejection rate. As the oxidizing agent, peroxide oxidizing agents such as hydrogen peroxide, percarbonate, peracetic acid and percarbonate, and chlorine oxidizing agents such as hypochlorite and chlorine water are used. An oxidation treatment with an oxide-based oxidizing agent is preferred. The oxidation treatment is generally performed by passing an aqueous solution of these oxidizing agents through the module or immersing the permeable membrane in a chemical.

  In the case of oxidation treatment with a peroxide-based oxidizing agent, it can be performed by the method disclosed in Japanese Patent Application Laid-Open No. 2005-103342. For example, an aqueous solution of hydrogen peroxide of 0.2 wt% or more is applied to a polyamide-based reverse osmosis membrane. The oxidation treatment can be performed by contact for 1 hour or longer. In this case, the oxidation treatment is performed under the condition that the hydrogen peroxide concentration (% by weight) of the aqueous hydrogen peroxide solution × the contact time (hour) is in the range of 5 to 60. be able to. In the case of oxidation treatment with a chlorine-based oxidizing agent, it can be carried out by the methods described in JP-A No. 2000-334280, JP-B No. 5-1051 and the like, with a free chlorine concentration of 5-500 mg / L and pH of 6-13. Can be processed.

  After the oxidation treatment, it is necessary to perform the step of imparting hydrophilicity by reacting a solution of a substance capable of crosslinking reaction or polymerization reaction such as glyoxal and epichlorohydrin, which has been carried out by conventional oxidation treatment, with the membrane subjected to oxidation treatment. However, it is possible to proceed to the next rejection rate improving agent treatment step as it is, but it is preferable to carry out a rinsing step with pure water or other cleaning liquid.

Rejection enhancing agent in the rejection enhancing agent treatment of the present invention is a rejection enhancing agent composed mainly of organic matter, the rejection enhancing agent treatment, by transmitting film soluble substances such as water-soluble organic substances and inorganic electrolytes As long as the rejection rate is improved, it can be used without any particular limitation. Examples of such a blocking rate improver include water-soluble polymer compounds and ionic or nonionic polymers. For ionic polymers, but that use of a cationic polymer and an anionic polymer by contacting separately stepwise cationic polymer and an anionic polymer, and preferably alternately supplying, rejection Since the improvement effect increases, it is preferable. Nonionic polymers as blocking rate improvers equivalent to these include compounds having a polyalkylene glycol chain that is a hydrophilic or polar nonionic polymer , and these may be used in combination. I can . 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.

As rejection enhancing agent usable for the can be used those known as the compound having a cationic polymer and an anionic polymer, and polyalkylene glycol chain, as described in Patent Document 1, 3, In addition, those having other ability to improve the rejection rate can be used. The rejection enhancing agent can be used, ionic polymer according to Patent Document 3 (polyamidine, polystyrene sulfonic acid), and compounds having a polyethylene glycol chain having a weight average molecular weight 2000 to 6000 described in Patent Document 1 can give. Examples of the compound having a polyalkylene glycol chain include polyethylene glycol or polyethylene glycol derivatives.

The weight average molecular weight of the compound having a polyalkylene glycol chain can be used in combination is not particularly limited, preferably 1,000 to 10,000, more preferably 2,000 to 6,000, more preferably 3,000 to 5,000.
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.)

Preferred rejection enhancing agent that can be used in the present invention, the weight average molecular weight of 100,000 or more, particularly 300,000 or more, more Ri Oh a million or more water-soluble polymers, mosquito thione polymer and an anionic high Molecule.

  Examples of the cationic polymer used in the above-described blocking rate improver include, for example, polyvinylamine, polyallylamine, polyacrylamide, chitosan, primary amine compounds such as those obtained by adding a primary amine group to polystyrene, and polyethylenimine and the like. 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.

Cationic polymer having a structural unit represented by the general formula [5], and acrylonitrile or methacrylonitrile, N- vinylcarboxamides, N - isopropenyl carboxylic acid amide, N- vinyl carboxylic acid imide or N- It can be produced by copolymerizing with isopropenylcarboxylic acid imide, hydrolyzing the resulting copolymer polymer, and amidineating it. 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 polymer used in the present invention include a water-soluble polymer having a carboxyl group such as polyacrylic acid and polymethacrylic acid, and a water-soluble polymer having a sulfonic acid group such as polystyrene sulfonic acid, dextran sulfuric acid, 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 stably stabilized without greatly reducing the flux.

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

As the blocking rate improver, a suitable agent is selected according to the material and form of the permeable membrane to be treated, and is used after being dissolved in a solvent such as pure water or water to be treated. Rejection enhancing agent treatment is a treatment to contact treatment with a compound having polyalkylene glycol chain of the, or a cationic polymer and an anionic polymer separately. When a plurality of types of blocking rate improvers are used, the blocking rate improving agent treatment can be performed in a mixed state or separately in contact with the permeable membrane. The concentration of the blocking rate improving agent varies depending on the type of each drug, the permeable membrane, the 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. It is subjected to the above-treated blocking RitsuMuko with. In the case where a plurality of blocking rate improvers are used in combination, they may be mixed and passed, or may be passed separately while shifting the time.

Rejection enhancing agent treatment by a rejection enhancing agent, in contact with supply rejection enhancing agent permeable membrane processing target module, to improve the rejection 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. 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 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 operating pressure when supplying the aqueous solution containing a rejection rate improver to the primary side of the module with the above 0.3 MPa, the ratio of the supply amount of the aqueous solution containing permeated water / rejection enhancing 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 rejection rate improving method of the present invention, the permeation membrane that has been subjected to the rejection rate improving agent treatment with a specific rejection rate improving agent is further brought into contact with a treatment liquid containing another rejection rate improving agent to perform the rejection rate improving agent treatment. As a result, the effect of improving the rejection rate can be enhanced. In particular, when the treatment is performed with the blocking rate improvers having different molecular weights, the treatment can be performed sequentially from the one having the lower molecular weight. In the case of treatment with an ionic polymer, a second rejection rate improvement that includes a different ionic polymer in a permeable membrane that has been treated with a first rejection rate improvement agent that includes a specific ionic polymer. The treatment can be performed by alternately contacting the agent one or more times. Can be performed rejection enhancing agent treatment before and after subsequently passed through this before passing liquid suspension of rejection enhancing agents, as such or after discharging a previous rejection enhancing agent, the rejection enhancing agent after Can be processed. In this case, preferably carried out by passing water a treatment liquid containing a rejection enhancing agent to the primary side of the module.

The permeable membrane obtained by the above-described method of improving the rejection rate has an improved rejection rate with the flux of the permeable membrane being increased, 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 of improving the rejection rate, and the rejection rate is improved with the flux of the permeable membrane being increased, and the high state is maintained for a long time.

  The permeable membrane treatment method of the present invention is a permeable membrane treatment method in which a permeable membrane treatment is performed by permeating a liquid to be treated through the permeable membrane obtained by the above-described inhibition rate improving method, and the permeable membrane treatment is performed with the permeable membrane having a high flux. The rate can be improved and the high state can be maintained for a long time, whereby the organic matter removal effect is high and stable treatment is possible over a long period of time. The supply and permeation of the liquid to be treated can be performed in the same way as a normal permeable membrane treatment. However, when treating a liquid to be treated containing a hardness component such as calcium or magnesium, a dispersant and scale prevention are added to the raw water. Agents and other agents may be added.

Transmission Makusho sense of the present invention uses the permeable membrane obtained by the above rejection enhancing methods, it is transmitted through the liquid to be treated permeable membrane can be carried out by a transmission film processing apparatus for permeable membrane treatment. As a result , the rejection rate is improved while the flux of the permeable membrane is high, and the high state can be maintained for a long time. This provides a high effect of removing organic substances and enables stable treatment over a long period of time.

A preferred permeation membrane treatment apparatus of the present invention comprises a permeation membrane module that passes a liquid to be treated on the primary side and takes out the permeate from the secondary side, and an oxidant that passes through the primary side of the module for oxidation. treatment and oxidation treatment apparatus for performing, on the primary side of the module, was passed through the rejection enhancing agent composed mainly of organic matter, permeable membrane device comprising a rejection enhancing agent treatment device for performing a rejection enhancing agent treatment It is.

  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, the permeable membrane treatment is performed, and the oxidation processing device oxidizes the primary side of the module. Oxidation treatment is performed by passing an agent, and a blocking rate improver treatment is performed by passing a blocking rate improver mainly composed of an organic substance on the primary side of the module by a blocking rate improver treatment device. The rejection of the permeable membrane can be improved with the membrane flux increased, and these improvement effects can be maintained in a high state.

  The present invention relates to water treatment for recovering and reusing wastewater containing high or low concentration TOC discharged in the electronic device manufacturing field, semiconductor manufacturing field, and other various industrial fields, or from industrial water or city water. Effectively applied to water treatment for pure water production. Although the to-be-processed water which this invention makes object is not specifically limited, It can use suitably for organic substance containing water, for example, TOC = 0.01-100 mg / L, Preferably it is 0.1-30 mg / L It is suitably used for the treatment of water containing organic matter. Examples of such organic substance-containing water include electronic device manufacturing plant effluent, transport machinery manufacturing plant effluent, organic synthesis plant effluent, printing plate making / painting plant effluent, and the like, or primary treated water thereof.

According to the present invention, after an oxidation treatment is performed by bringing an oxidant into contact with the permeable membrane, a blocking rate improver treatment is performed in which a specific blocking rate improver is brought into contact with the permeable membrane to improve the blocking rate of the permeable membrane. Accordingly, the rejection rate can be improved while the flux of the permeable membrane is increased, and these improvement effects can be maintained in a high state, whereby the organic matter removal effect is high and stable treatment can be performed 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 acid / alkaline cleaning liquid tank, 14 is a hydrogen peroxide aqueous solution tank, 15 is a blocking rate improver A aqueous solution tank, and 16 is a blocking rate improver B aqueous solution. A tank for water to be treated, P1 is a pump for passing water to be treated, P2 is a pump for passing chemicals, P3 is a pump for passing an aqueous solution of a rejection rate A, and P4 is a pump for passing an aqueous solution of a rejection rate B. V1 to V22 are valves. 1 and 2 show main piping and valves, and other valves, gauges and piping are not shown.

  1 and 2, when the treated water is subjected to RO treatment, the valves V1, V2, V3, V4, V5, and V22 are opened, the other valves are closed, and the pump P1 is operated to treat the treated water. The treated water in the tank 11 is supplied to the primary side 3 of the RO membrane module 1 and RO membrane separation is performed by the RO membrane 2, and the permeated water is taken out from the secondary side 4 as treated water. Concentrated water is returned from the primary side 3 to the water tank 11 to be treated, and part of the concentrated water 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 V17 are opened, and a part of the permeate is stored in the treated water tank 12. In some cases, the valves V18, V19, V20 and V21 are opened, and the permeated water is acid / alkaline cleaning liquid tank 13, hydrogen peroxide aqueous solution tank 14, blocking rate improver A aqueous solution tank 15 and blocking rate improver B. It can be fed to the aqueous solution tank 16 and used for dilution, adjustment, etc. of the cleaning solution, hydrogen peroxide, and aqueous solution for increasing the rejection.

  When chemical cleaning is performed when the RO membrane performance (flux and rejection rate) decreases due to RO treatment, the pump P1 is stopped, valves V2, V4, V8, V13 are opened, and other valves Is closed, the pump P2 is operated, and the cleaning liquid in the acid / alkaline cleaning liquid tank 13 is introduced into the primary side 3 of the RO membrane module 1 and then circulated back into the tank 13 again. 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 tank 13 by opening the valves V6 and V18. After circulating the cleaning liquid for a predetermined time, in some cases, the pump P2 is stopped and the chemical liquid is kept stationary for a certain time, and then the drain pipe (not shown) provided in the acid / alkaline cleaning liquid tank 13 To the outside of the system. Either the alkaline cleaning solution or the acidic cleaning solution may be performed first, or may be repeated twice or more, considering the state of RO membrane performance degradation and the type of blocking rate improver. To decide. The acid / alkaline cleaning liquid tank 13 may be divided into an acidic cleaning liquid tank and an alkaline cleaning liquid tank.

  When performing oxidation treatment with hydrogen peroxide, the valves V2, V4, V9, V14 are opened, the other valves are closed, the pump P2 is operated, and the hydrogen peroxide solution in the hydrogen peroxide solution tank 14 is removed from the RO membrane. After being introduced into the primary side 3 of the module 1, it is circulated back to the tank 14 again. At this time, the valve V5 may be opened to allow part of the hydrogen peroxide solution to pass through the membrane and be discharged out of the system. Alternatively, the valves V6 and V19 may be opened to return the hydrogen peroxide aqueous solution permeated through the membrane to the tank 14. After the aqueous hydrogen peroxide solution is circulated for a predetermined time, the pump P2 is stopped in some cases and the chemical solution is allowed to stand for a fixed time, and then the drain pipe (not shown) provided with the aqueous hydrogen peroxide solution in the tank 14 ) To the outside of the system.

  When rinsing the chemical solution in the RO membrane module 1, the valves V2, V3, V7 are opened, the other valves are closed, and the primary side 3 of the RO membrane module 1 is washed with the treated water in the treated water tank 12. Then, it is discharged out of the system through the valve V3. This rinsing with treated water can be performed after washing, after oxidation treatment with hydrogen peroxide, or when changing the type of washing solution.

In Figure 1, 1 if the type aqueous solution comprising a rejection enhancing agent performs rejection enhancing agent treatment, meets the rejection enhancing agent A solution only rejection enhancing agent A solution tank 15, the valve V2, V4 V10, V15 are opened, the other valves are closed, the pump P2 is operated, and the rejection rate improver A aqueous solution in the rejection rate improver A aqueous solution tank 15 is introduced into the primary side 3 of the RO membrane module 1. Then, it is circulated so as to return to the tank 15 again. At this time, the valve V5 may be opened and a part of the rejection rate improving agent A aqueous solution may be permeated through the membrane and discharged out of the system. However, the valves V6 and V20 may be opened and the membrane may pass through the rejection rate improving agent A aqueous solution. Is preferably returned to the tank 15. After the rejection rate improver A aqueous solution is circulated for a predetermined time, it is discharged out of the system through a drain pipe (not shown) provided in the tank 15.

  Next, the valves V2, V3, V6, V7, V20 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 aqueous solution for increasing the rejection rate is increased. A part is discharged out of the system through the valve V3, and the remaining part is discharged out of the system through the tank 15.

In Figure 1, different if the rejection enhancing agent with the treating rejection enhancing agents are, for example each cationic polymer solution to the rejection enhancing agent A solution tank 15 and the rejection enhancing agent B solution tank 16 First, the valves V2, V4, V10, V15 are opened, the other valves are closed, the pump P2 is operated, and the cationic polymer aqueous solution in the tank 15 for the blocking rate improver A aqueous solution is operated. Is introduced into the primary side 3 of the RO membrane module 1 and then circulated back into the tank 15 again. At this time, the valve V5 may be opened to allow a portion of the cationic polymer aqueous solution to permeate through the membrane and be discharged out of the system. However, the valve V6 and V20 may be opened to allow the cationic polymer aqueous solution to permeate the membrane. It is preferable to return to the tank 15. After the cationic polymer aqueous solution is circulated for a predetermined time, it is discharged out of the system through a drain pipe (not shown) provided in the blocking rate improver A aqueous solution tank 15.

  Next, after the valves V2, V4, V11, V16 are opened and the other valves are closed, the anionic polymer aqueous solution in the tank 16 for the rejection rate improving agent B aqueous solution is introduced into the primary side 3 of the RO membrane module 1. Circulate back to the tank 16 again. At this time, the valve V5 may be opened to allow a part of the anionic polymer aqueous solution to pass through the membrane and be discharged out of the system. However, the valves V6 and V21 may be opened to pass the membrane-permeable anionic polymer aqueous solution to the tank. It is preferable to return to 16. After the anionic polymer aqueous solution is circulated for a predetermined time, the anionic polymer aqueous solution is discharged out of the system from a drain pipe (not shown) provided in the blocking rate improver B aqueous solution tank 16.

Next, the valves V2, V3, V6, V7 are opened, at least one of V20 and V21 is opened, the other valves are closed, and the primary side of the RO membrane module 1 is treated with treated water in the treated water tank 12. 3 is rinsed, and a part of the aqueous solution for improving the rejection rate is discharged out of the system through the valve V3, and the remainder is discharged out of the system through either the tank 15 or 16. The rinsing with the treated water is preferably performed between the rejection rate improving agent treatment with the rejection rate improving agent A aqueous solution and the rejection rate improving agent treatment with the rejection rate improving agent B aqueous solution. The treatment with the rejection rate improver A and the treatment with the rejection rate improver B may be repeated twice or more alternately.

2, 1 in the case where the type aqueous solution comprising a rejection enhancing agent performs rejection enhancing agent treatment, meets the rejection enhancing agent A solution only rejection enhancing agent A solution tank 15, first the valve V10 The pump P3 is operated, the rejection rate improver A aqueous solution in the rejection rate improver A aqueous solution tank 15 is introduced into the water tank 11 to be treated, and then the pump P1 is activated, and the valves V1, V2, V4, V22 is opened, other valves are closed, and the water to be treated containing the blocking rate improver A in the water tank 11 to be treated is introduced into the primary side 3 of the RO membrane module 1 and then returned to the tank 11 again. To circulate. At this time, the valves V3 and V5 are opened to allow the treated water containing the rejection rate improving agent A to pass through the membrane to obtain treated water, and to remove the treated water containing the rejection rate improving agent A. It is preferable to discharge out of the system. By doing in this way, the time of a rejection rate improvement agent process can be shortened. After the water to be treated containing the rejection rate improving agent A is circulated for a predetermined time, the valve V10 is closed and the pump P3 is stopped, and the introduction of the rejection rate improving agent A aqueous solution is stopped.

  Next, the valves V2, V3, and V7 are opened, the other valves are closed, the pump P1 is stopped, the pump P2 is operated, and the primary side 3 of the RO membrane module 1 is treated with the treated water in the treated water tank 12. While cleaning, the to-be-processed water containing the inhibition rate improving agent A is discharged out of the system through the valve V3.

2, different if the rejection enhancing agent with the treating rejection enhancing agents are, for example each cationic polymer solution to the rejection enhancing agent A solution tank 15 and the rejection enhancing agent B solution tank 16 First, the valve V10 is opened and the pump P3 is operated to introduce the cationic polymer aqueous solution in the tank 15 for the blocking rate improver A aqueous solution into the water tank 11 to be treated. P1 is activated, valves V1, V2, V4, and V22 are opened, and the other valves are closed, and the water to be treated containing the cationic polymer in the water tank 11 to be treated is the primary side 3 of the RO membrane module 1. After being introduced into the tank, it is circulated so as to return to the tank 11 again. At this time, the valves V3 and V5 are opened to allow a part of the water to be treated containing the cationic polymer to pass through the membrane to obtain the treated water, and a part of the water to be treated containing the cationic polymer is used in the system. It is preferable to discharge outside. By doing in this way, the time of a rejection rate improvement agent process can be shortened. After circulating the water to be treated containing the cationic polymer for a predetermined time, the valve V10 is closed and the pump P3 is stopped to stop the introduction of the cationic polymer aqueous solution.

Next, the valve V11 is opened, the pump P4 is operated, the aqueous anionic polymer solution in the tank 16 for the rejection rate improving agent B aqueous solution 16 is introduced into the water tank 11 to be treated, and then the pump P1 is operated to operate the valves V1, V2 , V4, V22 are opened, the other valves are closed, and the treated water containing the anionic polymer in the treated water tank 11 is introduced into the primary side 3 of the RO membrane module 1 and then again in the tank 11 Cycle to return. At this time, the valves V3 and V5 are opened to allow the treated water containing the anionic polymer to pass through the membrane to obtain treated water, and to remove the treated water containing the anionic polymer from the system. It is preferable to discharge to By doing in this way, the time which stops the driving | operation of RO processing apparatus can be shortened. After circulating the water to be treated containing the anionic polymer for a predetermined time, the valve V11 is closed and the pump P4 is stopped to stop the introduction of the aqueous anionic polymer solution.

Next, the valves V2, V3, and V7 are opened, the other valves are closed, the pump P1 is stopped, the pump P2 is operated, and the primary side 3 of the RO membrane module 1 is treated with the treated water in the treated water tank 12. While rinsing, the polymer aqueous solution is discharged out of the system through the valve V3. The rinsing with the treated water is preferably performed between the treatment with the aqueous cationic polymer solution and the treatment with the aqueous anionic polymer solution. The rinsing step is shortened or omitted by stopping the introduction of the aqueous solution for improving the rejection rate and then performing the RO treatment with the treated water for a predetermined time (about three times the residence time of the treated water tank 11). You can also. Note the rejection enhancing agent treatment with cationic polymer solution, rejection enhancing agent treatment with the anionic polymer solution may be performed twice or more alternately repeated.

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. They can be shared or omitted. Further, the RO membrane treatment process, the cleaning process, the hydrogen peroxide treatment process, and the rejection rate improving agent treatment process may be performed in different places. That is, only the RO membrane 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), accommodated in a separately prepared vessel at the destination, washed, and oxidized hydrotreating, or rejection enhancing agent treatment may be performed. Conversely, after performing the surface modification treatment, the RO element can be moved to another location to perform the RO membrane treatment. In the case of FIG. 2, the rejection rate improver aqueous solution is supplied to the treated water tank 11, and these rejection rate improver aqueous solutions are connected to the pipe connecting the treated water tank 11 and the RO membrane module 1. Direct line injection may be used.

Hereinafter, the present invention will be described in more detail with reference to examples. The rejection of the present embodiment was calculated by the following equation.
Blocking rate (%) = [1- (solute concentration of permeate × 2) / (solute concentration of feed solution + solute concentration of concentrate)] × 100

[Comparative Example 1]:
The RO membrane loaded into the RO device was a polyamide RO membrane NTR-759HR manufactured by Nitto Denko Corporation. The wastewater from the electronic device manufacturing factory containing 3.5 mg / L of the TOC component was adjusted to pH 6.0, and RO treatment was performed under the conditions of a pressure of 1.2 MPa and a water temperature of 20 ° C. using the RO device.
The flux decreased from the initial 0.95 m / d to 0.55 m / d after 100 hours. The TOC rejection was 99% or more at the initial stage and after 100 hours.

[Example 1]:
The membrane to be loaded into the RO device was a polyamide RO membrane NTR-759HR manufactured by Nitto Denko Corporation with a surface modification treatment. Surface as the modification treatment, and 20 hours the hydrogen peroxide treatment at 1 wt% aqueous hydrogen peroxide solution, 5 mg / L cationic polymer (polyvinyl amidine, molecular weight 3.5 million) in the treated 2 hours rejection enhancing agent, further anionic polymer (sodium polyacrylate, molecular weight of 3,000,000) by 5 mg / L was treated for 2 hours rejection enhancing agent.
Using this RO device, RO treatment was performed under the same conditions as in Comparative Example 1. As a result, the TOC rejection was 99% or more at the initial stage and after 100 hours. The flux was 0.80 m / d after 100 hours with respect to the initial flux of 0.88 m / d, and the flux could be kept high.

[Comparative Example 2-1]:
The membrane loaded in the RO device was a polyamide RO membrane ES-20 manufactured by Nitto Denko Corporation. The RO water containing 1.0 mg / L of the TOC component was subjected to RO treatment under the conditions of a pressure of 0.75 MPa, a water temperature of 20 to 25 ° C., and a pH of 6.5 to 8.0 using the RO device. As a result, the initial flux was 0.98 m / d, but the flux after 100 hours was 0.71 m / d. The TOC rejection was 97.2% in the initial stage and 98.3% after 100 hours.

[Comparative Example 2-2]:
The membrane loaded in the RO device was a polyamide RO membrane ES-20 manufactured by Nitto Denko Corporation which was surface-modified. In the surface modification treatment, hydrogen peroxide treatment was performed for 10 hours with a 1 wt% aqueous hydrogen peroxide solution. Using this RO device, RO treatment was performed under the same conditions as in Comparative Example 2-1. As a result, the initial flux was 1.14 m / d, but the flux after 100 hours was 0.98 m / d. The flux was kept high, but the TOC rejection was 96.5% in the initial stage and 97.0% after 100 hours.

[Reference Example 1 -1]
The membrane loaded in the RO device was a polyamide RO membrane ES-20 manufactured by Nitto Denko Corporation which was surface-modified. The surface modification treatment, 1 weight% of 10 hours the hydrogen peroxide treatment with aqueous hydrogen peroxide solution, and 2 hours rejection enhancing agent treatment with polyethylene glycol 1 mg / L (molecular weight 3000). Using this RO device, RO treatment was performed under the same conditions as in Comparative Example 2-1. As a result, the initial flux was 0.94 m / d, but the flux after 100 hours was 0.88 m / d. The TOC rejection was 98.4% in the initial stage and 98.7% after 100 hours.

[Comparative Example 2-3]:
The membrane loaded in the RO device was a polyamide RO membrane ES-20 manufactured by Nitto Denko Corporation which was surface-modified. The surface modification treatment, and 2 hours rejection enhancing agent treatment with polyethylene glycol 1 mg / L (molecular weight 3000). Using this RO device, RO treatment was performed under the same conditions as in Comparative Example 2-1. As a result, the initial flux was 0.77 m / d, but the flux after 100 hours was 0.64 m / d. The TOC rejection was 98.6% in the initial stage and 99.0% after 100 hours.

[ Reference Example 1-2 ]:
The membrane loaded in the RO device was a polyamide RO membrane ES-20 manufactured by Nitto Denko Corporation which was surface-modified. The surface modification treatment was the same surface modification treatment as in Reference Example 1 -1.
Using this RO apparatus, 2 mg / L of a polymer obtained by copolymerizing 3-allyloxy-hydroxypropanesulfonic acid and acrylic acid at a monomer ratio of 10 to 30:70 to 90 as a dispersant was added to the water to be treated. The RO treatment was performed under the same conditions as in Comparative Example 2-1. As a result, the initial flux was 0.94 m / d, but the flux after 100 hours was 0.91 m / d. The TOC rejection at that time was 98.5% in the initial stage, and 98.7% after 100 hours.

As is clear from the above Examples and Reference Examples and Comparative Examples, using the RO membrane subjected to the surface modification treatment in the present invention, using a dispersant as necessary, while maintaining a stable flux, It can be seen that RO-treated water from which electrolytes and organic medium and small molecules are highly removed 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.

DESCRIPTION OF SYMBOLS 1 RO membrane module 2 RO membrane 3 Primary side 4 Secondary side 11 Treated water tank 12 Treated water tank 13 Acid / alkaline cleaning liquid tank 14 Hydrogen peroxide aqueous solution tank 15 Rejection rate improver A aqueous solution tank 16 Rejection rate Tank for improver B aqueous solution

Claims (2)

After the oxidation treatment by contacting the permeable membrane with an oxidant,
It is a method for performing a blocking rate improver treatment for improving the blocking rate of a permeable membrane by bringing a blocking rate improving agent into contact with the permeable membrane ,
The oxidizing agent is selected from peroxides and chlorinating agents;
The method for improving the rejection of a permeable membrane, wherein the treatment for improving the rejection is a treatment in which a cationic polymer and an anionic polymer are contacted separately . A permeable membrane treatment method for performing a permeable membrane treatment by allowing a liquid to be treated to permeate through a permeable membrane obtained by the method according to claim 1.

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