Abstract: There is provided an apparatus for removing fine particles having membranes for removing fine particles in a liquid, wherein a microfiltration membrane or ultrafiltration membrane having a positive charge and a microfiltration membrane or ultrafiltration membrane having a negative charge are arranged in series. There is also provided a method for removing fine particles using the apparatus. Liquids may be passed through the membrane having a negative charge and the membrane having a positive charge in order; thereby, extrafine particles having a particle size of 50 nm or smaller, especially of 10 nm or smaller, in the liquids can be removed highly. The liquid passing may be carried out in the order reverse thereto.

Abstract: A method for producing permselective membrane includes preparing a support membrane having selective permeability and a lipid membrane containing a channel substance, the lipid membrane being formed on a surface of the support membrane. Excess lipids are removed with an acid or an alkali, and the support membrane has a permeation flux of 20 L/(m2·h) or more and a desalination capacity of 1% to 20% at a pressure of 0.1 MPa.

Abstract: An organic solvent treatment method for removing particulates from an organic solvent used in a manufacturing step of electronic components is characterized by comprising a step of bringing the organic solvent into contact with a treatment material that has a positive or negative electric charge in water and has a moisture content of 3% by mass or more. An organic solvent treatment material, which is to be used in the manufacturing step of electronic components and which is for removing particulates from an organic solvent by coming into contact with the organic solvent used in the manufacturing step of electronic components, has a positive or negative electric charge in water.

Abstract: A permselective membrane is provided with a support membrane having selective permeability, and a coating layer formed on a surface of the support membrane and including a lipid bilayer membrane containing a channel substance. The support membrane includes a polyamide membrane providing permeation flux of 35 L/(m2·h) or more at a pressure of 0.1 MPa. A method for producing the permselective membrane includes a step of treating a polyamide membrane with chlorine to produce the support membrane and a step of forming the lipid bilayer membrane on the support membrane.

Abstract: Provided is an agent and a liquid for cleaning an RO membrane to remove effectively foulants that can not be sufficiently removed with conventional cleaning agents when an RO membrane particularly an aromatic polyamide RO membrane has been used for water treatment and has become fouled resulting in degradation of performance such as permeation flux, pressure difference, and salt rejection rate. The agent for cleaning an RO membrane includes an aliphatic amide and/or an aromatic amide. Also provided is a method for cleaning an RO membrane with the cleaning agent or the cleaning liquid. The aliphatic amide and/or the aromatic amide particularly an aliphatic amide and/or an aromatic amide being soluble in water and having a relatively low molecular weight remove effectively foulants adhered on an aromatic polyamide RO membrane.

Abstract: The ultrapure-water production system includes an auxiliary treatment apparatus and a dead-end filtration apparatus. The auxiliary treatment apparatus treats water such that the number of microparticles present in water treated by the auxiliary treatment apparatus is 800 to 1200 particles/mL. The dead-end filtration apparatus includes a filtration membrane that is a microfiltration membrane having pores formed in the surface of the membrane at an opening ratio of 50% to 90% with a size of 0.05 to 1 ?m, and having a thickness of 0.1 to 1 mm, or an ultrafiltration membrane having pores formed in the surface of the membrane with a size of 0.005 to 0.05 ?m, the number of the pores being 1E13 to 1E15 pores/m2, the ultrafiltration membrane having a thickness of 0.1 to 1 mm and a transmembrane pressure of 0.02 to 0.10 MPa at a permeation flux of 10 m3/m2/d.

Abstract: The present invention provides a RO membrane or a FO membrane comprising a coating layer made of a phospholipid bilayer membrane and formed on a surface of a porous membrane body, having a high water permeate flow rate and salt rejection performance, the membrane being a permselective membrane comprising a porous membrane having a pore size of 5 nm to 50 nm and a coating layer made of a phospholipid bilayer and formed on a surface of the porous membrane, wherein (i) the phospholipid bilayer comprises phospholipid, amphotericin B, and ergosterol; (ii) a content of the amphotericin B is 3 to 20 mol % based on the phospholipid bilayer; (iii) a total content of the ergosterol and the amphotericin B in the phospholipid bilayer is 10 to 30 mol %.

Abstract: A permselective membrane includes a support membrane having selective permeability and a lipid membrane containing a channel substance, the lipid membrane being formed on a surface of the support membrane, wherein the support membrane has a permeation flux of 20 L/(m2·h) or more and a desalination capacity of 1% to 20% at a pressure of 0.1 MPa.

Abstract: Provided are a cleaning agent and a cleaning liquid that prevent a reduction in the rejection rate of an RO membrane which may occur when the RO membrane is cleaned and a method for cleaning an RO membrane with the cleaning liquid. The agent for cleaning an RO membrane includes a urea derivative. The urea derivative preferably includes urea (H2N—CO—NH2) and/or biuret (H2N—CO—NH—CO—NH2). The cleaning liquid is an aqueous solution produced by diluting the cleaning agent. The method for cleaning an RO membrane uses the cleaning liquid. Urea and biuret have a structure analogous to amide bonds included in aromatic polyamide RO membranes, and have a strong affinity for amide bond portions. Urea and biuret adsorb onto the amide bond portions, and prevent the amide bonds from being broken by the cleaning liquid.

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 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: 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: The present invention provides a RO membrane or a FO membrane comprising a coating layer made of a phospholipid bilayer membrane and formed on a surface of a porous membrane body, having a high water permeate flow rate and salt rejection performance, the membrane being a permselective membrane comprising a porous membrane having a pore size of 5 nm to 50 nm and a coating layer made of a phospholipid bilayer and formed on a surface of the porous membrane, wherein (i) the phospholipid bilayer comprises phospholipid, amphotericin B, and ergosterol; (ii) a content of the amphotericin B is 3 to 20 mol % based on the phospholipid bilayer; (iii) a total content of the ergosterol and the amphotericin B in the phospholipid bilayer is 10 to 30 mol %.

Abstract: Provided is an agent and a liquid for cleaning an RO membrane to remove effectively foulants that can not be sufficiently removed with conventional cleaning agents when an RO membrane particularly an aromatic polyamide RO membrane has been used for water treatment and has become fouled resulting in degradation of performance such as permeation flux, pressure difference, and salt rejection rate. The agent for cleaning an RO membrane includes an aliphatic amide and/or an aromatic amide. Also provided is a method for cleaning an RO membrane with the cleaning agent or the cleaning liquid. The aliphatic amide and/or the aromatic amide particularly an aliphatic amide and/or an aromatic amide being soluble in water and having a relatively low molecular weight remove effectively foulants adhered on an aromatic polyamide RO membrane.

Abstract: To provide a permselective membrane that includes a coating layer constituted by a phospholipid bilayer, the coating layer being capable of withstanding the pressure applied during a water treatment and being resistant to detachment and a method for producing the permselective membrane. A permselective membrane comprising a membrane main body having permselectivity and a coating layer disposed on a surface of the membrane main body, the coating layer including a phospholipid bilayer including a channel substance, wherein the phospholipid bilayer includes phospholipids that are a first phospholipid including an acyl group constituted by a fatty acid including an unsaturated fatty acid and a second phospholipid including two acyl groups each constituted by a fatty acid that is a saturated fatty acid having 16 to 24 carbon atoms.

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: An agent for cleaning an RO membrane, which includes an aldonic acid and/or a salt of an aldonic acid, removes effectively foulants that cannot be sufficiently removed with conventional cleaning agents when an RO membrane used for water treatment. In a method for cleaning an RO membrane with the cleaning agent or the cleaning liquid, while the detachment and hydrolysis effects are achieved by performing cleaning under alkaline conditions, chelation of heavy metals is caused by the aldonic acid and/or the salt of an aldonic acid. When an anionic surfactant is used in combination with the aldonic acid and/or the salt of an aldonic acid, the anionic surfactant causes the detachment of foulants. When a polyol having a molecular weight of 1000 or less is used in combination with the aldonic acid and/or the salt of an aldonic acid, the polyol causes wetting and swelling of foulants.

Abstract: Provided is a cleaning agent capable of preventing a reduction in the rejection rate of an RO membrane which may occur when the membrane is cleaned, the cleaning agent including a membrane protectant that is a basic or hydrophobic amino acid, a peptide containing the amino acid as a constituent amino acid, or a derivative of the amino acid or the peptide. The cleaning agent may further include at least one agent selected from the group consisting of an alkaline agent, a combined chlorine agent, and an oxidizing agent. The amino acid is preferably arginine, lysine, or phenylalanine. Also provided are a cleaning liquid that is an aqueous solution produced by diluting the cleaning agent and a method for cleaning a reverse osmosis membrane with the cleaning liquid.

Abstract: In a subsystem or water-feed path located upsteam of a use point in an ultrapure water production/supply process, fine particles having a particle diameter of 50 nm or less, in particular 10 nm or less are highly removed. A device for removing fine particles in water has a membrane filtration device including a microfiltration membrane or an ultrafiltration membrane having a weak cationic functional group. The microfiltration membrane or the ultrafiltration membrane having a weak cationic functional group is preferred to have a polyketone film with the weak cationic functional group. Negatively-charged particles in water are adsorbed by the weak cationic functional group and can thus be removed.

Abstract: Provided are a cleaning agent and a cleaning liquid that prevent a reduction in the rejection rate of an RO membrane which may occur when the RO membrane is cleaned and a method for cleaning an RO membrane with the cleaning liquid. The agent for cleaning an RO membrane includes a urea derivative. The urea derivative preferably includes urea (H2N—CO—NH2) and/or biuret (H2N—CO—NH—CO—NH2). The cleaning liquid is an aqueous solution produced by diluting the cleaning agent. The method for cleaning an RO membrane uses the cleaning liquid. Urea and biuret have a structure analogous to amide bonds included in aromatic polyamide RO membranes, and have a strong affinity for amide bond portions. Urea and biuret adsorb onto the amide bond portions, and prevent the amide bonds from being broken by the cleaning liquid.