Wastewater containing 1,4-dioxane and detergent from metal washing processes was treated using UV ozone oxidation and ion exchange resin. The chemically stable 1,4-dioxane was decomposed easily and quickly by UV ozone oxidation.
The oxidized water was deionized using ion exchange resin by applying a mixed bed resin system. The electric conductivity of the effluent from the ion exchange resin column was less than 1.2 μS cm^－1. COD（Chemical Oxygen Demand）and TOC（Total Organic Carbon）, which indicate organic matter contents, were 1.0 mg dm^－3 and 0.15 mg dm^－3, respectively. This purified water is reusable as rinsing water during surface finishing.
Based on these experiments, we devised a practical recycling system by which contaminated wastewater can be decontaminated and reused as purified water on an industrial scale at a surface finishing factory. A salient benefit of this combined process （UV ozone oxidation and ion exchange resin method）is that it uses no chemicals and that it entails no production of salts that must be removed before using the treated water. These results suggest that this process causes no secondary pollution, and that it has a high probability of practical application as recycling water during surface finishing.