Method for controlling slime in reverse osmosis membrane apparatus

Patent metadata

Field	Value
Publication number	US-12083480-B2
Application number	US-202117180845-A
Country	US
Kind code	B2
Filing date	Feb 21, 2021
Priority date	Aug 23, 2018
Publication date	Sep 10, 2024
Grant date	Sep 10, 2024

Abstract

A method for controlling slime is used in a reverse osmosis membrane apparatus and has a water-supplying step of supplying water to be treated to the reverse osmosis membrane. The water-supplying step includes a first water-supplying step in which a slime controlling agent X which contains 2,2-dibromo-3-nitrilopropionamide (DBNPA) and a slime controlling agent Y which contains at least one type selected from a group consisting of components (A) to (D) are added to the water to be treated which has a pH of 10 or less, and the water to be treated which contains the slime controlling agent X and the slime controlling agent Y is supplied to the reverse osmosis membrane. The component (A) is mixture of 5-chloro-2-methyl-4-isothiazolin-3-one (Cl-MIT) and 2-methyl-4-isothiazolin-3-one (MIT), the component (B) is chloramine compound, the component (C) is stabilized bromide, and the component (D) is glutaraldehyde.

First claim

What is claimed is:

1. A method for controlling slime in a reverse osmosis membrane apparatus, which is used in a reverse osmosis membrane apparatus and has a water-supplying step of supplying water to be treated to a reverse osmosis membrane, wherein
the water-supplying step comprises a first water-supplying step in which a slime controlling agent X which contains 2,2-dibromo-3-nitrilopropionamide (DBNPA) and a slime controlling agent Y which contains at least one type selected from a group consisting of the following components (A) to (D) are added to water to be treated which has a pH of 10 or less, and the water to be treated which contains the slime controlling agent X and the slime controlling agent Y is supplied to the reverse osmosis membrane,
Component (A): mixture of 5-chloro-2-methyl-4-isothiazolin-3-one (CI-MIT) and 2-methyl-4-isothiazolin-3-one (MIT)
Component (B): chloramine compound
Component (C): stabilized bromide
Component (D): glutaraldehyde, and
the first water-supplying step is run under at least one condition selected from a group consisting of the following operation conditions 1 to 3,
Operation condition 1: an operation condition in which the water is separated into permeated water and concentrated water and respectively taken out, and the permeated water is discarded
Operation condition 2: an operation condition in which the water is separated into permeated water and concentrated water and respectively taken out, and the permeated water is returned to raw water of the reverse osmosis membrane apparatus
Operation condition 3: an operation condition in which the water is separated into permeated water and concentrated water and respectively taken out, and the permeated water and the concentrated water are returned to raw water of the reverse osmosis membrane apparatus.

2. The method for controlling slime in a reverse osmosis membrane apparatus according to claim 1 , wherein the component (B): chloramine compound is at least one type selected from a group consisting of a component (B-1) and a component (B-2), wherein
the component (B-1) is a chloramine consisting of ammonium salt and chlorine, and the component (B-2) is at least one type selected from a group consisting of chlorosulfamic acid and chlorosulfamate.

3. The method for controlling slime in a reverse osmosis membrane apparatus according to claim 1 , wherein the water-supplying step further comprises a second water-supplying step in which water to be treated which does not contain the slime controlling agent X and the slime controlling agent Y is supplied to the reverse osmosis membrane.

4. The method for controlling slime in a reverse osmosis membrane apparatus according to claim 1 , wherein in the water-supplying step, the number of times of the water-supplying in the first water-supplying step is 1 to 14 times per week, and the water-supplying time per water-supplying is one hour or less.

5. The method for controlling slime in a reverse osmosis membrane apparatus according to claim 4 , wherein the number of times of the water-supplying in the first water-supplying step is once per day.

Assignees

• Kurita Water Ind Ltd

Inventors

• Endo Yoshihiko

Classifications

• C02F1/441

  by reverse osmosis · CPC title

• B01D2321/40

  Automatic control of cleaning processes · CPC title

• B01D2321/168

  Use of other chemical agents · CPC title

• B01D2321/162

  Use of acids · CPC title

• B01D65/02

  Membrane cleaning or sterilisation {; Membrane regeneration} · CPC title