Wash water processing method

A wash water processing method of reusing processed water formed of purr water used in a washing process in semiconductor liquid-crystal manufacturing or electronic-component plating, wherein:

• a wash water accommodation part into which processed water processed in a washing processing part flows and a filtration mechanism part fluidly connected to the accommodation part to which the processed water is sent from the wash water accommodation part;
• a sterilization and purification unit includes an ozone supply part which supplies ozone, an ultraviolet irradiation part which irradiates with ultraviolet rays, a nd a photocatalysis part which operates photocatalysis, the sterilization and purification unit being connected with the wash water accommodation part via an inflow path and outflow path;
• and;
• the filtration mechanism part includes a filter and a n ion-exchange resin;
• the wash water processing method comprising:
• mixing the processed water and ozone with the ozone supply part and generating ozone water;
• generating −OH (hydroxy radicals or OH radicals) in the ozone water with the ultraviolet irradiation part and the photocatalysis part to sterilize and purify the processed water;
• returning the processed water that has been sterilized and purified to the wash water accommodation part,
• mixing the processed water that has been sterilized and purified with the processed water accommodated in the wash water accommodation part, in order to dilute an ozone concentration of the processed water accommodated in the wash water accommodation part;
• and
• sending the processed water having a diluted ozone concentration via a supply flow path to the filtration mechanism part,
• wherein, in a state in which the ozone concentration of the processed water in the wash water accommodation part is adjusted, by selecting operation stop or restart of the ozone supply part, and by passing the processed water through both the filter and the ion-exchange resin, growth of bacteria in the filter and the ion-exchanging resin is suppressed, and oxidative deterioration of the filter and the ion-exchang resin is suppressed.