Water treatment method

Patent metadata

Field	Value
Publication number	US-11077403-B2
Application number	US-201716490161-A
Country	US
Kind code	B2
Filing date	Sep 15, 2017
Priority date	Mar 23, 2017
Publication date	Aug 3, 2021
Grant date	Aug 3, 2021

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.

First claim

The invention claimed is:

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.

2. 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.

Assignees

• Kurita Water Ind Ltd

Inventors

• Kameda Hidekuni
• Ishii Kazuki
• Chen Yaozhen

Classifications

• C02F9/00

  Multistage treatment of water, waste water or sewage · CPC title

• C02F1/42

  by ion-exchange (ion-exchange in general B01J) · CPC title

• B01D21/01

  using flocculating agents (for purifying water C02F1/52; for liquid radioactive waste G21F9/10) · CPC title

• C02F1/5245

  using basic salts, e.g. of aluminium and iron · CPC title

• C02F1/66

  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) · CPC title