Water treatment method and water treatment device

A water treatment method comprising:

• obtaining a permeate and a concentrate by treating, with a reverse osmosis membrane, a water to be treated to which a slime inhibitor containing an iodine-based oxidizing agent has been added, wherein
• a water tank in which the water to be treated is stored exists between an addition point of the slime inhibitor and the reverse osmosis membrane,
• the slime inhibitor is added to the water to be treated by intermittent addition, and at least one of an addition concentration of the slime inhibitor, an addition time of the slime inhibitor, a flow rate of the water to be treated, and a volume of the water tank is adjusted such that a value f(T) determined from formula (1) shown below becomes 0.5 or greater:
• [
• Formula
• ⁢
• 1
• ]
• 
• f
• ⁡
• (
• T
• )
• =
• C
• ⁡
• (
• V
• -
• F
• )
• 1000
• ⁢
• V
• ⁢
• {
• 1
• -
• (
• 1
• -
• F
• V
• )
• T
• +
• 1
• }
• (
• 1
• )
• (wherein in formula (1), C represents the addition concentration (mg/t as Cl2) of the slime inhibitor, T represents the addition time (min) of the slime inhibitor, F represents the flow rate (t/min) of the water to be treated, and V represents the volume (t) of the water tank).

A water treatment device comprising:

• a reverse osmosis membrane for obtaining a permeate and a concentrate by treating, with the reverse osmosis membrane, a water to be treated to which a slime inhibitor containing an iodine-based oxidizing agent has been added,
• a water tank which stores the water to be treated and is positioned between an addition point of the slime inhibitor and the reverse osmosis membrane, and
• a slime inhibitor addition line for adding the slime inhibitor to the water to be treated by intermittent addition, wherein
• at least one of an addition concentration of the slime inhibitor, an addition time of the slime inhibitor, a flow rate of the water to be treated, and a volume of the water tank is adjusted such that a concentration of the slime inhibitor at an outlet of the water tank becomes at least 0.5 mg/L as Cl2 without changing a CT value of the slime inhibitor.

A water treatment device comprising:

• a reverse osmosis membrane for obtaining a permeate and a concentrate by treating, with the reverse osmosis membrane, a water to be treated to which a slime inhibitor containing an iodine-based oxidizing agent has been added,
• a water tank which stores the water to be treated and is positioned between an addition point of the slime inhibitor and the reverse osmosis membrane, and
• a slime inhibitor addition line for adding the slime inhibitor to the water to be treated by intermittent addition, wherein
• at least one of an addition concentration of the slime inhibitor, an addition time of the slime inhibitor, a flow rate of the water to be treated, and a volume of the water tank is adjusted such that a value f(T) determined from formula (1) shown below becomes 0.5 or greater:
• [
• Formula
• ⁢
• 2
• ]
• 
• f
• ⁡
• (
• T
• )
• =
• C
• ⁡
• (
• V
• -
• F
• )
• 1000
• ⁢
• V
• ⁢
• {
• 1
• -
• (
• 1
• -
• F
• V
• )
• T
• +
• 1
• }
• (
• 1
• )
• (wherein in formula (1), C represents the addition concentration (mg/t as Cl2) of the slime inhibitor, T represents the addition time (min) of the slime inhibitor, F represents the flow rate (t/min) of the water to be treated, and V represents the volume (t) of the water tank).