There are very high values of the chemical oxidation demand (COD) in the effluent from pulp mills. The COD value of the effluent is still higher after traditional biological treatment. The biologically treated wastewater from pulp mill was irradiated using low energy EB. For the wastewater irradiated with a dose of less than 1kGy

its COD value was reduced to 1/4 of the value for unirradiated wastewater. Chromaticity of the irradiated-wastewater was also greatly decreased. The UV-visible spectra of a significant constituent of the wastewater indicated that the contaminants were degradated well.