Abstract: Provided are reverse-osmosis-membrane device capable of treating raw water including a large amount of membrane foulants, such as MBR-treated water, with stability while preventing a reduction in the amount of permeate, and a method for operating the reverse-osmosis-membrane device. The raw water includes a high-molecular organic substance having a molecular weight of 10,000 or more at a concentration of 0.01 ppm or more. The reverse-osmosis-membrane device includes a reverse-osmosis-membrane element including a membrane unit, the membrane unit including a reverse osmosis membrane having a thickness of 0.1 mm or less, a feed spacer disposed on a surface of the reverse osmosis membrane, and a permeate spacer disposed on the other surface of the reverse osmosis membrane. The reverse-osmosis-membrane device is operated at a permeation flux of 0.6 m/d or less.

Abstract: An object of the present invention is to provide a dispersant for treatment of water. The dispersant is used in a membrane separation process of water containing an organic compound having a phenolic hydroxy group and prevents a reduction in amount of the water permeating a separation membrane, which is caused by deposition of the organic compound onto the surface of the separation membrane. Provided are a dispersant for treatment of water containing an organic compound having a phenolic hydroxy group wherein the dispersant contains a polymer compound having a carbonyl group and a structure including a nitrogen atom bonded to a carbonyl carbon atom; and a method for treatment of water containing an organic compound having a phenolic hydroxy group, wherein the method includes adding the dispersant to the water.

Abstract: A method capable of effectively improving a rejection of a reverse osmosis membrane without remarkably reducing a permeation flux, even if the membrane is seriously degraded. An aqueous solution containing a first organic compound having a molecular weight of less than 200, a second organic compound having a molecular weight of 200 to less than 500, and a third organic compound having a molecular weight of 500 or more is passed through the reverse osmosis membrane. The first organic compound is preferably an amino acid or an amino acid derivative. The total concentration of the first organic compound and the second organic compound and the concentration of the third organic compound are each preferably 1 to 500 mg/L.

Abstract: Provide is a reverse osmosis membrane device that is capable of treating raw water containing membrane-fouling substance in large quantities, such as MBR-treated water, in a stable manner while preventing decreases in permeate flow rate, and a method for operating thereof. A method for operating a reverse osmosis membrane device that treats raw water containing high-molecular-weight organic matter, wherein the raw water contains high-molecular-weight organic matter having a molecular weight of 10,000 or more at a concentration of 0.01 ppm or more, wherein the reverse osmosis membrane device is equipped with a spiral-type reverse osmosis membrane element that has a membrane surface area satisfying the below formula (1), and wherein the reverse osmosis membrane device is operated at a permeate flux of 0.6 m/d or less: membrane surface area (m2)?n2×(11/16)??(1) wherein n represents a diameter (inches) of the reverse osmosis membrane element.

Abstract: A quality of treated water is improved without loss of stability in multi-stage reverse osmosis membrane treatment. Raw water in a raw water tank 1 is fed to a first-stage reverse osmosis membrane unit 3 by compression with a first pump 2, and concentrated water is discharged while permeated water is introduced into an intermediate tank 5 through a piping 4. The water in the intermediate tank 5 is fed to a second-stage reverse osmosis membrane unit 7 by compression with a second pump 6, and permeated water is taken out through a piping 8 while concentrated water is returned to the raw water tank 1 through a piping 9. The thickness of the raw water spacer of the reverse osmosis membrane units is more than 0.6 mm for the first stage and is 0.6 mm or less for the second stage.

Abstract: To provide a method for improving a rejection rate of an RO membrane, which further improves the stability of removal performance (rejection rate) and flux stability (sustainability of contamination resistance). In a method for improving a rejection rate of an RO membrane, including a step of allowing an aqueous solution containing a polyphenol to pass through an RO membrane, the method further includes a step of allowing an aqueous solution containing at least one type selected from the group consisting of a modified poly(vinyl alcohol), a high molecular polysaccharide, and a poly(amino acid) to pass through the RO membrane. The method preferably further includes a step of allowing an aqueous solution containing an organic compound having an amino group and having a molecular weight of 1,000 or less to pass through the RO membrane.

Abstract: A silicon wafer after being cleaned by using a cleaning liquid is rinsed by using carbonic water. According to such a silicon wafer cleaning method, generation of static due to a rinsing treatment is not caused, so that an electrostatic breakdown is not caused, adhesion of dirt to a cleaned silicon wafer surface due to the static is not caused, adhesion of metal impurities can be prevented in the rinsing treatment of the silicon wafer and, while giving consideration to the cost, furthermore, a rinsing treatment using a clean rinsing liquid free from causing any residue can be performed.

Abstract: The invention provides cleaning agents, cleaning liquids and cleaning methods that effectively remove contaminants which are impossible to remove sufficiently with conventional cleaning liquids at the occurrence of a decrease in performances such as permeation flux and salt rejection rate due to contamination of permeable membranes, in particular aromatic polyamide RO membranes used in water treatment. Permeable membranes are cleaned with a cleaning liquid which is an aqueous solution including a chloramine compound and an alkali agent and having a pH of 10 or above. The chloramine compound is preferably one obtained by mixing a compound having a primary amino group with hypochlorous acid and/or a hypochlorite.

Abstract: Provide is a method capable of effectively improving a rejection of a permeable membrane without remarkably reducing a permeation flux, even if the membrane is seriously degraded. The method for improving a rejection of a permeable membrane supplies an aqueous solution (excluding an aqueous solution having a pH of 7 or less) containing a compound having an amino group and a molecular weight of 1,000 or less through the permeable membrane (amino-treatment step). Since the low molecular weight amino compound is supplied through the permeable membrane, degraded portions of the membrane can be restored without remarkably reducing the permeation flux thereof, and the rejection thereof can be effectively improved.

Abstract: A method capable of effectively improving a rejection of a reverse osmosis membrane without remarkably reducing a permeation flux, even if the membrane is seriously degraded. An aqueous solution containing a first organic compound having a molecular weight of less than 200, a second organic compound having a molecular weight of 200 to less than 500, and a third organic compound having a molecular weight of 500 or more is passed through the reverse osmosis membrane. The first organic compound is preferably an amino acid or an amino acid derivative. The total concentration of the first organic compound and the second organic compound and the concentration of the third organic compound are each preferably 1 to 500 mg/L.

Abstract: A silicon wafer after being cleaned by using a cleaning liquid is rinsed by using carbonic water. According to such a silicon wafer cleaning method, generation of static due to a rinsing treatment is not caused, so that an electrostatic breakdown is not caused, adhesion of dirt to a cleaned silicon wafer surface due to the static is not caused, adhesion of metal impurities can be prevented in the rinsing treatment of the silicon wafer and, while giving consideration to the cost, furthermore, a rinsing treatment using a clean rinsing liquid free from causing any residue can be performed.

Abstract: Provided is a method capable of effectively improving the rejection of a membrane without considerably lowering the permeation flux, even when the membrane has significantly degraded. The method of improving the rejection of a permeable membrane includes a step (amino treatment step) of passing an aqueous solution (amino treatment water) having a pH of 7 or less and containing an amino group-containing compound having a molecular weight of 1000 or less through the permeable membrane. After this amino treatment step, water having a higher pH than the amino treatment water is allowed to pass through the permeable membrane. Thus, by allowing the low-molecular-weight amino compound to pass through the membrane, a degraded portion of the membrane can be restored without considerably lowering the permeation flux of this permeable membrane, and the rejection can be effectively improved.

Abstract: An agent for increasing the rejection with a permeable membrane which comprises an ionic macromolecule having a weight-average molecular weight of 100,000 or greater; a process for increasing the rejection with a permeable membrane which comprises treating a permeable membrane with the agent; a permeable membrane which is treated in accordance with the process; and a process for water treatment which comprises using the permeable membrane are disclosed. By using the above agent, an increased rejection of inorganic electrolytes and organic compounds soluble in water can be maintained for a long time easily and safely at the location of the use of the membrane without extreme decrease in the flux of permeation in the membrane separation using a selective permeable membrane such as a nano filtration membrane and a reverse osmosis membrane.

Abstract: There is provided a hybrid polymer fiber material containing a non-electrolytic polymer and an electrolytic polymer and having properties and advantages of both polymers, and provided a method of producing the hybrid polymer fiber material, and provided a filter made of the hybrid polymer fiber material. A voltage is applied between a nozzle 1 and a target 3 (opposite surface) such that the nozzle 1 is positive and such that the target 3 is negative. Then, the mixed solution of the non-electrolytic polymer and the electrolytic polymer is ejected from the nozzle 1 to the target 3, so that hybrid polymer fiber material 2 containing the non-electrolytic polymer and the electrolytic polymer is accumulated on the target 3. The hybrid polymer fiber material 2 is used as a filter for fluid filtration.

Abstract: This invention provides a method for improving the blocking rate of a permeable membrane, which can reduce a lowering in permeation flux of the permeable membrane to improve the blocking rate, particularly against organic matter, and thus to realize a high organic matter removing effect and stable treatment, and a permeable membrane, a permeable membrane treatment method, and a permeable membrane apparatus. A blocking rate improving agent of a hydrophilic polymer free from a hydrophobic group having 8 or more carbon atoms is supplied to a primary side of a permeable membrane module to deposit the blocking rate improving agent onto the permeable membrane and thus to treat the permeable membrane with the blocking rate improving agent.

Abstract: A method for treatment with a reverse osmosis membrane to reduce decrease in flux that occurs even under the conditions that water supplied to a reverse osmosis membrane treatment apparatus contains only a trace amount of iron and that the formation of scales of substances such as calcium and silica is prohibited. A method for performing a treatment with a reverse osmosis membrane to treat raw water containing iron at 1000 ?g/L or less as total iron with a reverse osmosis membrane, including a step of adding a compound having a sulfo group to the raw water.

Abstract: An agent for increasing the rejection of a nanofiltration membrane or a reverse osmosis membrane which comprises a compound having a polyalkylene glycol chain having a weight-average molecular weight of 2,000 to 6,000; a process for increasing the rejection of a nanofiltration membrane or a reverse osmosis membrane which comprises bringing the nanofiltration membrane or the reverse osmosis membrane into contact with an aqueous solution of a compound having a polyalkylene glycol chain which is obtained by diluting the agent for increasing the rejection of a nanofiltration membrane or a reverse osmosis membrane described above with water; a nanofiltration membrane or a reverse osmosis membrane exhibiting a rejection increased in accordance with the process; and a process and an apparatus for water treatment using the nanofiltration membrane or the reverse osmosis membrane.

Abstract: A detergent and a method for washing applicable to selectively permeable membranes for proposed, which can attain washing of selectively permeable membranes deteriorated in its membrane performance, such as the flux, in an efficient manner within a brief time at a higher detergent effect without causing deterioration of the selectively permeable membranes and without damaging safety to human and to environment with superior handling aspect. The detergent contains a polyol having a molecular weight not higher than 400 and, if necessary, an organic solvent.

Abstract: An agent for increasing the rejection with a permeable membrane which comprises an ionic macromolecule having a weight-average molecular weight of 100,000 or greater; a process for increasing the rejection with a permeable membrane which comprises treating a permeable membrane with the agent; a permeable membrane which is treated in accordance with the process; and a process for water treatment which comprises using the permeable membrane are disclosed. By using the above agent, an increased rejection of inorganic electrolytes and organic compounds soluble in water can be maintained for a long time easily and safely at the location of the use of the membrane without extreme decrease in the flux of permeation in the membrane separation using a selective permeable membrane such as a nano filtration membrane and a reverse osmosis membrane.

Abstract: A detergent and a method for washing applicable to selectively permeable membranes are proposed, which can attain washing of selectively permeable membranes deteriorated in its membrane performance, such as the flux, in an efficient manner within a brief time at a higher detergent effect without causing deterioration of the selectively permeable membranes and without damaging safety to human and to environment with superior handling aspect. A detergent comprising a polyol having a molecular weight not higher than 400 and, if necessary, an organic solvent is supplied to the concentrate chamber 3 of the module 1 to carry out washing of the selectively permeable membrane 2 by bringing it into contact with the selectively permeable membrane 2 and, on requirement, water or an alkaline solution is further supplied from the water tank 6 or from the alkali storage 8 to the concentrate chamber 3 of the module 1, in order to recover the membrane performance of the selectively permeable membrane 2.