Characteristics and treatability of persistent colors in biologically treated wastewater effluents

Reuse of wastewater effluents is a priority in Korea; however, color content has been difficult to control, even when water is used for toilet flushing and cleaning. UV radiation and a UV/H2O2 process were found to be effective in removing persistent color. An optimum initial concentration of hydrogen peroxide was identified, after which the color removal rate declined. The rate constant of color removal was high compared with humic acid. Aquatic humic substance concentrations and molecular weight distributions were used to characterize the color content of the effluents after each process. This process indicated that aquatic humic substances are related to organic matter, a source of color.