A wash water processing method for semiconductor manufacture, liquid-crystal manufacture, and electronic components, having a washing processing part for cleaning at semiconductor manufacture or liquid-crystal manufacture and cleaning electronic components, and a wash water storage part connected to the washing processing part via a circulation flow path in order to allow pure water after cleaning to flow in as processed water for storage thereof,
- the method comprising:
- a circulation step of a first circulation system in a sterilization and purification unit and having an ozone supply part connected to this wash water storage part via a flow-in flow path and a flow-out flow path so that processed water is circulatable;
- a filtration mechanism part configured to include a filtration device of a filter connected to a subsequent part following stage of the wash water storage part via a filtration flow path and an ion exchange resin,
- a circulation flow path connecting a subsequent part following stage of the filtration mechanism part and the washing processing part,
- TOC concentration measurement means and TOC concentration adjustment means provided midway in the circulation flow path,
- a circulation step of a second circulation system having the washing processing part, the wash water storage part, and the filtration mechanism part, the filtration mechanism part and the washing processing part being connected so as to configure the entire wash water processing apparatus without ends, in a circulatable state;
- and
- a control step including the TOC concentration adjustment means which is adjustment means for performing to discharge processed water and supply pure water to prevent elution of TOC from each portion configuring the wash water storage part and the filtration mechanism part and,
- the apparatus comprises a control apparatus having a memory part storing an arithmetic expression capable of calculating a discharge amount of processed water and a supply amount of pure water in accordance with an ozone-water concentration and a TOC concentration of processed water,
- wherein:
- bacteria in the processed water in the wash water storage part are sterilized and decomposed by circulation between the wash water storage part and the sterilization and purification unit;
- the ozone-water concentration is controlled to a concentration by mixture of processed water flowing in from the washing processing part and stored in the wash water storage part and sterilized and dissolved processed water and by autolysis of ozone;
- the control apparatus controls the ozone supply part, by passing low-concentration ozone water having an ozone-water concentration equal to or less than 5.37 mg/L from the wash water storage part through both the filter and the ion exchange resin in order to suppress oxidative deterioration of the filter and the ion exchange resin to reduce a decrease in filtration performance of the filtration mechanism part;
- the low-concentration ozone water reduces an occurrence of slime occurring to the filter and the ion exchange resin themselves;
- and
- in accordance with a TOC concentration eluted from each portion configuring the wash water storage part and the filtration mechanism part, by discharge of processed water and supply of pure water at the TOC concentration adjustment means, before the washing processing part, the TOC concentration of wash water for use is controlled at a control value equal to or less than a predetermined value in pure water to allow use for cleaning at the washing processing part.