Effect of electron-beam irradiation on white water generated in paper mills

Abstract

In this study, we evaluated the effect of electron-beam irradiation on the water quality of the white water generated in paper mills. Four samples of white water were collected from a fine paper mill and from a specialty paper mill. Changes in the water quality were observed, depending on the amount of electron-beam irradiation. Two samples of white water were obtained from the fine paper mill's disc-filtration system. When the electron-beam dose was increased from 3 to 9 kGy, the pH of these samples decreased slightly, but no significant changes in electrical conductivity or turbidity were observed. However, the total dissolved solids (TDS) and chemical oxygen demand (COD) decreased. The differences in the water-quality trends were not large among the white-water samples. White water from the special paper mill was collected before it entered the ozone-oxidation tank and after it exited from the tank, and the properties of the samples were examined after electron-beam irradiation (10 kGy). The pH, electrical conductivity, and turbidity exhibited the same tendencies as for the white water obtained from the fine paper mill, and the TDS and COD also decreased. In particular, when the intensity of electron-beam irradiation of the ozonated white water was increased, the TDS, COD, and chromaticity improved significantly. We conclude that electron-beam irradiation reduces the COD and chromaticity of white water. ? 2020 Korean Technical Assoc. of the Pulp and Paper Industry. All rights reserved.