# US 11,077,403 B2 · Water treatment method

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- Number: US 11,077,403 B2
- Document ID: US11077403B2
- Status: Granted
- Kind: B2
- Application number: 16/490,161
- Filed: 2017-09-15
- Published: 2019-12-26
- Granted: 2021-08-03
- Earliest claimed: 2017-03-23
- Assignees: Kurita Water Industries Ltd.
- Applicants: Kurita Water Industries Ltd.
- Inventors: Hidekuni Kameda; Kazuki Ishii; Yaozhen Chen
- Web page: https://patentgrep.com/patent/US11077403B2

## CPC

- B01D 61/04: Feed pretreatment
- B01D 21/01: using flocculating agents (for purifying water C02F1/52; for liquid radioactive waste G21F9/10)
- B03D 3/02: Coagulation
- B03D 3/06: Flocculation
- C02F 1/44: by dialysis, osmosis or reverse osmosis {(general membrane separation processes B01D61/00, membrane modules B01D63/00, electrodialysis C02F1/4693, combination of membrane modules and bioreactors C02F3/1268)}
- C02F 1/5245: {using basic salts, e.g. of aluminium and iron}
- C02F 1/56: Macromolecular compounds
- B01D 2311/04: Specific process operations in the feed stream; Feed pretreatment
- B01D 2311/12: Addition of chemical agents
- B01D 2311/2642: Aggregation, sedimentation, flocculation, precipitation or coagulation
- B01D 2311/2649: Filtration
- C02F 1/283: {using coal, charred products, or inorganic mixtures containing them}
- C02F 1/42: by ion-exchange (ion-exchange in general B01J)
- C02F 1/441: {by reverse osmosis}
- C02F 1/444: {by ultrafiltration or microfiltration}
- C02F 1/66: by neutralisation; pH adjustment (for degassing C02F1/20; using ion-exchange C02F1/42; for flocculation or precipitation of suspended impurities C02F1/52; for removing dissolved compounds C02F1/58)
- C02F 1/76: with halogens or compounds of halogens {(C02F1/4674 takes precedence)}
- C02F 9/00: Multistage treatment of water, waste water or sewage
- C02F 2301/08: Multistage treatments, e.g. repetition of the same process step under different conditions
- C02F 2303/22: Eliminating or preventing deposits, scale removal, scale prevention (C02F1/042, C02F1/4602, C02F5/00 take precedence)
- C02F 2305/02: Specific form of oxidant
- 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)
- B03D: FLOTATION; DIFFERENTIAL SEDIMENTATION (sedimentation in general B01D21/00; in combination with other separation of solids B03B; sink-float separation B03B5/28; detergents, soaps C11D)
- 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)

## Abstract

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.

## Claims

### Claim 1

A method for treating water, the method comprising:
adding, as coagulants, a polymer compound having a phenolic hydroxyl group and an iron-based coagulant to water to be treated;
filtering coagulated water with a clarification filter; and
subjecting 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 the phenolic hydroxyl group and an addition concentration of the iron-based coagulant is constant and is 0.01 to 0.25,
the addition concentration of the polymer compound having the phenolic hydroxyl group is 1 to 15 mg/L,
the addition concentration of the iron-based coagulant is controlled according to a TOC concentration of the treated water, and the polymer compound having the phenolic hydroxyl group is added following the addition concentration of the iron-based coagulant, and
the addition concentration of the iron-based coagulant is between 5 and 300 mg/L when the TOC concentration varies in a range between 0.1 and 5.0 mg/L.

### Claim 2 (depends on 1)

The method for treating water according to claim 1, wherein the addition concentration of the iron-based coagulant is between 5 and 50 mg/L when the TOC concentration is 0.1 mg/L, the addition concentration of the iron-based coagulant is between 40 and 120 mg/L when the TOC concentration is 2 mg/L, and the addition concentration of the iron-based coagulant is between 150 and 300 mg/L when the TOC concentration is 5 mg/L.