Water treatment method and water treatment apparatus

Abstract

To minimize an amount of hydrogen peroxide required for controlling the production of bromic acid in an ozone / hydrogen peroxide treatment. The ozone / hydrogen peroxide treatment is performed at an ozone injection rate by which a predetermined dissolved ozone concentration of the water subjected to an ozone treatment alone can be maintained or at an ozone injection rate by which a specific ratio of absorbance at a specific wavelength of the water to absorbance at a specific wavelength of the water subjected to the ozone treatment alone can be achieved. It is preferable that the injection rate of hydrogen peroxide is 0.01 to 5 times the ozone injection rate on a mass basis.

Description

technical field [0001] The invention relates to a water treatment method and a water treatment device. Background technique [0002] Ozone treatment is the main method of deep water purification treatment. Ozone is effective for sterilization, deodorization and decolorization of treated water such as purified water, but bromide ions (Br - ) is oxidized to produce bromate ions (BrO 3 - ). BrO 3 - The generation, there is through Br - And the generation route of ozone (ozone route) and through Br - Two routes (radical routes) of radical species such as hydroxyl radicals (·OH) generated by self-decomposition of ozone. When using the ozone route, the Br in the treated water - , react with ozone to generate hypobromite ion (OBr - ), the hypobromite ion is further oxidized by ozone to generate BrO 3 - . When the free radical route is used, BrO is generated by free radicals and ozone 3 - . In addition, it has been reported that BrO 3 - Mainly generated by free rad...

AI Technical Summary

Problems solved by technology

However, according to this method, since the ozone treatment is performed in the previous stage, BrO of about several μg / L is produced even if the concentration of dissolved ozone is controlled. 3 - , cannot correspond to the stricter BrO expected in the future 3 - control

In addition, BrO 3 - Once formed, it cannot be removed by ozone treatment, combined treatment with ozone and hydrogen peroxide, or ordinary activated carbon treatment

In addition, combined treatment with ozone and hydrogen peroxide is used in the latter stage, due to the inhibition of BrO 3 - For the formation of ozone, the relative ozone injection rate must reach excess hydrogen peroxide, but there is a disadvantage that the cost of hydrogen peroxide solution increases

As a result, the concentration of hydrogen peroxide remaining in the treated water increases, and the load to remove hydrogen peroxide in the subsequent activated carbon treatment increases.

Images