Method for removing biofilm

Patent metadata

Field	Value
Publication number	US-2022212966-A1
Application number	US-202017604683-A
Country	US
Kind code	A1
Filing date	Apr 28, 2020
Priority date	May 10, 2019
Publication date	Jul 7, 2022
Grant date	—

Abstract

The present invention is a method for removing a biofilm containing a metal and formed in a water system, wherein the biofilm is brought into contact with (a) a compound having a hydroxyl radical generation ability and (b) a reducing agent.

First claim

1 . A method for removing a biofilm containing a metal and formed in a water system, wherein the biofilm is brought into contact with
(a) a compound having a hydroxyl radical generation ability (hereinafter also referred to as component (a)), and (b) a reducing agent (hereinafter also referred to as component (b)).

2 . The method for removing a biofilm according to claim 1 , wherein the biofilm is brought into contact with a liquid composition containing the component (a), the component (b) and water.

3 . The method for removing a biofilm according to claim 2 , wherein, in the liquid composition, the component (a) has a concentration of 50 ppm or more and 5000 ppm or less, and the component (b) has a concentration of 50 ppm or more and 50000 ppm or less.

4 . The method for removing a biofilm according to claim 2 , wherein, in the liquid composition, the component (a) has a concentration of 50 ppm or more and 5000 ppm or less, and the component (b) has a concentration of 50 ppm or more and 5000 ppm or less.

5 . The method for removing a biofilm according to claim 1 , wherein the components (a) and (b) are brought into contact at a pH of 2.0 or more and 10.0 or less.

6 . The method for removing a biofilm according to claim 1 , wherein the component (a) is one or more selected from hydrogen peroxide, percarbonate salts and organic peracids.

7 . The method for removing a biofilm according to claim 1 , wherein the component (b) is one or more selected from ascorbic acid or salts thereof, vitamin C extracted from natural products, tannic acid, erythorbic acid or salts thereof, N,N-diethylhydroxylamine, ascorbic acid derivatives or salts thereof, hydrosulfites, pyrosulfites, sulfites, hydrogensulfites, thiosulfates, thioureadioxide, gallic acid, methylhydroquinone, dimethylhydroquinone, trimethylhydroquinone, t-butylhydroquinone, methoxyhydroquinone and chlorohydroquinone.

8 . The method for removing a biofilm according to claim 1 , wherein the components (a) and (b) are brought into contact with the biofilm together with
(c) a monovalent or divalent organic acid or a salt thereof with a primary dissociation constant of 1.2 or more and 4.6 or less (hereinafter also referred to as component (c)).

9 . The method for removing a biofilm according to claim 8 , wherein the component (c) is one or more organic acids or salts thereof selected from malonic acid, malic acid, 3-hydroxypropionic acid, succinic acid, lactic acid, tartaric acid, glycolic acid, maleic acid, fumaric acid, gluconic acid and salts thereof.

10 . The method for removing a biofilm according to claim 8 , wherein the component (c) has a concentration of 50 ppm or more and 5000 ppm or less in the liquid composition.

11 . A method for removing a biofilm containing a metal and formed in a water system, wherein the biofilm is brought into contact with a liquid composition containing (a) a compound having a hydroxyl radical generation ability (hereinafter also referred to as component (a)), (b) a reducing agent (hereinafter also referred to as component (b)), (c) a monovalent or divalent organic acid or a salt thereof with a primary dissociation constant of 1.2 or more and 4.6 or less (hereinafter also referred to as component (c)), and water,
wherein the component (a) is one or more compounds selected from hydrogen peroxide and percarbonate salts, the component (b) is ascorbic acid or salts thereof, and the component (c) is one or more organic acids or salts thereof selected from malonic acid, malic acid, 3-hydroxypropionic acid, succinic acid, lactic acid, tartaric acid, glycolic acid, maleic acid, fumaric acid, gluconic acid and salts thereof, wherein, in the liquid composition, the component (a) has a concentration of 80 ppm or more and 1000 ppm or less, and the component (b) has a concentration of 80 ppm or more and 1000 ppm or less, and wherein the components (a) and (b) are brought into contact at a pH of 3.5 or more and 10.0 or less.

12 . The method for removing a biofilm according to claim 11 , wherein the component (c) has a concentration of 80 ppm or more and 1000 ppm or less in the liquid composition.

13 . The method for removing a biofilm according to claim 8 , wherein the components (a) and (c) are brought into contact at a mass ratio of component (a)/component (c) of 0.01 or more and 100 or less.

14 . The method for removing a biofilm according to claim 8 , wherein the components (b) and (c) are brought into contact at a mass ratio of component (b)/component (c) of 0.01 or more and 100 or less.

15 . The method for removing a biofilm according to claim 1 , wherein the components (a) and (b) are brought into contact at a mass ratio of component (a)/component (b) of 0.01 or more and 100 or less.

16 . The method for removing a biofilm according to claim 1 , wherein the biofilm contains one or more metals selected from iron, manganese, nickel and copper.

17 . The method for removing a biofilm according to claim 1 , wherein the biofilm contains, per mg of the biofilm in a wet state, the metal in an amount of 0.5 ng or more and 50000 ng or less.

18 . The method for removing a biofilm according to claim 1 , wherein the water system is a cooling system comprising a water-cooled cooling tower.

19 . The method for removing a biofilm according to claim 1 , wherein the water system comprises a water flow path and/or a water storage tank.

Assignees

• Kao Corp

Inventors

• Hosokawa Kento
• Chiba Masashi
• Yamamoto Tetsuji
• Tanaka Takanori

Classifications

• C02F1/722

  Oxidation by peroxides · CPC title

• C02F1/70 Primary

  by reduction {(C02F1/4676 takes precedence)} · CPC title

• C02F2101/203

  Iron or iron compound · CPC title

• C11D3/0042

  Reducing agents · CPC title

• C02F2103/023

  Water in cooling circuits · CPC title