# US 2025/0051203 A1 · Microorganism contamination prevention method for water system

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- Number: US 2025/0051203 A1
- Document ID: US20250051203A1
- Status: Published application
- Kind: A1
- Application number: 18/721,662
- Filed: 2022-12-15
- Published: 2025-02-13
- Earliest claimed: 2021-12-20
- Assignees: Kurita Water Industries Ltd.
- Applicants: Kurita Water Industries Ltd.
- Inventors: Yuta OHTSUKA; Chikako SHIMPO; Gou NAKAGAWA; Junichi TAKAHASHI; Kunihiro HAYAKAWA
- Web page: https://patentgrep.com/patent/US20250051203A1

## CPC

- C02F 1/76: with halogens or compounds of halogens {(C02F1/4674 takes precedence)}
- C02F 1/766: {by means of halogens other than chlorine or of halogenated compounds containing halogen other than chlorine}
- B01D 61/06: Energy recovery
- C02F 1/441: {by reverse osmosis}
- C02F 1/50: by addition or application of a germicide or by oligodynamic treatment {(C02F1/4606, C02F1/467, C02F1/76 take precedence)}
- C02F 1/68: by addition of specified substances, e.g. trace elements, for ameliorating potable water (medicinal water A61K)
- B01D 2311/04: Specific process operations in the feed stream; Feed pretreatment
- B01D 2311/2634: Oxidation
- C02F 2303/04: Disinfection
- C02F 2303/185: The treatment agent being halogen or a halogenated compound
- C02F 2303/20: Prevention of biofouling
- Y02A 20/131: Reverse-osmosis
- C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes)
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE

## Abstract

A method for preventing microorganism fouling in a water system containing a reducing agent, said microorganism fouling prevention method for a water system being characterized by adding a stabilized chlorine-based oxidizing agent composed of a chlorine-based oxidizing agent and a sulfamic acid compound, with the ratio of the sulfamic acid compound relative to 1 mol effective chlorine of the chlorine-based oxidizing agent being 1-1.5 mol, and/or a stabilized bromine-based oxidizing agent composed of a bromine-based oxidizing agent and a sulfamic acid compound, with the ratio of the sulfamic acid compound relative to 1 mol effective chlorine conversion amount of the bromine-based oxidizing agent being 1-1.5 mol, to the water system, such that the addition concentration of the stabilized chlorine-based oxidizing agent and/or the stabilized bromine-based oxidizing agent relative to the reducing agent concentration in the water system is 2.5 times or more by molar ratio.

## Claims

### Claim 1

A method for suppressing microorganism fouling in a water system, comprising:
adding a reducing agent; and
adding a stabilized chlorine-based oxidizing agent composed of a chlorine-based oxidizing agent and a sulfamic acid compound, with a ratio of the sulfamic acid compound to 1 mole of effective chlorine of the chlorine-based oxidizing agent being 1 to 1.5 moles, and/or a stabilized bromine-based oxidizing agent composed of a bromine-based oxidizing agent and a sulfamic acid compound, with a ratio of the sulfamic acid compound to 1 mole of effective chlorine conversion amount of the bromine-based oxidizing agent being 1 to 1.5 moles to the water system that contains the reducing agent, characterized in that
a concentration of the reducing agent in the water system is 0.01 mg/L-Cl2 or more to 5 mg/L-Cl2 or less, and
an addition concentration of the stabilized chlorine-based oxidizing agent and/or the stabilized bromine-based oxidizing agent relative to a concentration of the reducing agent in the water system is 2.5 times to 10 times in molar ratio.

### Claim 2 (depends on 1)

The method for suppressing microorganism fouling in the water system according to claim 1, characterized in that the water system is a reverse osmosis membrane water supply system.

### Claim 3

(canceled)

### Claim 4 (depends on 1)

The method for suppressing microorganism fouling in the water system according to claim 1, characterized in that the reducing agent is sodium bisulfite.

### Claim 5

(canceled)

### Claim 6 (depends on 2)

The method for suppressing microorganism fouling in the water system according to claim 2, characterized in that the reducing agent is sodium bisulfite.