Method for operating reverse osmosis membrane device, a slime control method, and a water treatment device

A method for operating a reverse osmosis membrane device, the method comprising:

• a first step for intermittently adding an oxidation-based slime inhibitor to water to be treated and intermittently supplying the water to be treated containing the oxidation-based slime inhibitor to a reverse osmosis membrane device;
• and
• a second step for adding an organic-based slime inhibitor to water to be treated at least during a period other than the addition period of the first step and supplying the water to be treated containing the organic-based slime inhibitor to the reverse osmosis membrane device,
• wherein an addition concentration of the oxidation-based slime inhibitor to water to be treated is adjusted to be higher than an addition concentration of the organic-based slime inhibitor to water to be treated,
• wherein the addition concentration of each addition of the oxidation-based slime inhibitor to water to be treated is 0.1 to 600 mg/L of the water system in terms of total chlorine concentration, wherein the total chlorine concentration is determined in accordance with JIS K 0400-33-10:1999,
• wherein the addition concentration of each addition of the organic-based slime inhibitor to water to be treated is 0.01 to 100 mg (as chemical mass)/L of the water system,
• wherein the first step has a first intermittent addition period per unit and a first addition-free period per unit, and the first intermittent addition period per unit is shorter than the first addition-free period per unit,
• wherein the oxidation-based slime inhibitor is a chemical containing one or more combined halogen compounds selected from chlorosulfamic acid, chlorosulfamate, bromosulfamic acid, and bromosulfamate,
• wherein the organic-based slime inhibitor is selected from one or more of isothiazoline compounds, halocyanoacetamide compounds, aldehyde compounds, or oxime compounds, or a chemical containing one or more compounds selected from these, and
• wherein the water to be treated contains the oxidation-based slime inhibitor or the organic-based slime inhibitor and is separated into concentrated water and permeated water by the reverse osmosis membrane.