Japan Aviation Electronics Industry, Limited

Kurita Water Industries Ltd.

Kazuki Ishii

Junji Oosaka

Takeharu Naito

Ryou Katou

Takahiro Kawakatsu

Junichi Takahashi

Kunihiro Hayakawa

Yaozhen Chen

Hidekuni Kameda

The present invention is a method for operating a demineralization apparatus provided with a plurality of demineralizing lines arranged in parallel and having demineralizers, the method comprising passing through some of the demineralizing lines water to be treated to produce demineralized water while passing through another demineralizing line(s) dilute water from a dilute water tank to perform washing of the line(s), and returning water used for said washing back to the dilute water tank, and being characterized by, when the water quality of the dilute water is on the high salts concentration side past a predefined value, discharging part of the dilute water so as to let said part join the water to be treated and providing a new supply of dilute water for replenishment.

Method for operating demineralization apparatus

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A water treatment chemical for membranes, which contains a polymer compound having a carboxyl group and a sulfo group, preferably a polymer compound represented by formula (1). A membrane treatment method wherein this water treatment chemical for membranes is added to membrane feed water when water to be treated, which contains an organic compound having a phenolic hydroxy group, is subjected to a membrane separation treatment. In the formula, m and n represent molar percentages of respective structural units; (m+n) is 90-100%; and R represents an anionic group containing a sulfo group.

Water treatment chemical for membranes and membrane treatment method

A solution-type water treatment chemical, includes, as one, gluconic acid (salt) and a surfactant having an HLB determined by the following equation (1) satisfying the following equation (2), wherein in a relationship between concentrations of the gluconic acid (salt) and the surfactant and a molecular weight and HLB of the surfactant, the gluconic acid (salt) and the surfactant are contained such that the water treatment chemical does not form a gel or precipitate.=(&#x3a3;inorganic value/&#x3a3;organic value)&#xd7;10&#x2003;&#x2003;(1)Molecular weight&#x3e;&#x2212;34.4&#xd7;+1005&#x2003;&#x2003;(2)

Water treatment chemical, method for preparing same, and method for washing polyamide reverse osmosis membrane

A method for treating water, the method including adding, as coagulants, a polymer compound having a phenolic hydroxyl group and an iron-based coagulant to water to be treated, filtering the coagulated water with a clarification filter, and subjecting the filtered water to a reverse osmosis membrane treatment, wherein the addition of the coagulants is controlled such that a ratio between an addition concentration of the polymer compound having a phenolic hydroxyl group and an addition concentration of the iron-based coagulant is constant.

Water treatment method

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.

Agent, liquid, and method for cleaning reverse osmosis membrane

Provided is a scale inhibitor for RO membranes which effectively inhibits the precipitation of calcium carbonate in an RO membrane treatment without increasing the phosphorus concentration in effluent and which can be used even in the RO membrane treatment of feed in which high-M-alkalinity concentrate having a calcium hardness level of 100 to 600 mg/L-CaCOand an M alkalinity of 1000 to 16000 mg-CaCO/L is produced. A scale inhibitor for reverse osmosis membranes which inhibits the formation of calcium carbonate scale in an RO membrane treatment, the scale inhibitor including components (A) and (B) below. An RO membrane treatment method including adding the scale inhibitor for RO membranes to RO feed. Component (A): Terpolymer of maleic acid, an acrylic acid alkyl ester, and vinyl acetate, Component (B): Homopolymer of carboxylic acid

Scale inhibitor for reverse osmosis membranes and reverse osmosis membrane treatment method

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 (HN&#x2014;CO&#x2014;NH) and/or biuret (HN&#x2014;CO&#x2014;NH&#x2014;CO&#x2014;NH). 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.

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Tokyo, Japan

Kazuki Ishii