Abstract: An electronic parts members, or the like, such as the silicon wafer, etc., is washed with wash water. The wash water is prepared by dissolving a hydrogen gas or ozone gas in ultra pure water and has a negative or positive oxidation-reduction potential. This wash water has remarkably improved detergency for electronic parts. In addition, when the pH of the wash water is adjusted, the electronic parts members can be washed more effectively.

Abstract: The disclosed process for treatment of organic wastewater such as manure-washing wastewater discharged from the livestock industry or wastewater discharged from the food industry comprises the step (1) of subjecting the organic wastewater to an aerobic biological treatment, and the step (2) of subjecting the treated water obtained in the step (1) to a biological treatment in a lagoon. The process may further comprise, before the step (1), the step of subjecting a mixture of the organic wastewater and part of the treated water obtained in the step (1), recycled back and combined therewith, to a biological denitrification treatment. The treated water obtained by the process is so improved in quality as to enable safe disposal thereof. A submerged biofilter process (packed-bed reactor process) is preferably used in the aerobic biological treatment since it can remarkably improve the overall stability of the whole wastewater treatment process to obtain a stable quality of treated water.