Peroxidation treatment of dye manufacturing wastewater in the presence of ultraviolet light and ferrous ions

This study was performed to investigate the removal of COD and color from a dye manufacturing plant wastewater using the H2O2/UV/Fe2+ process. Comparison of removal efficiencies were made among the H2O2/UV, the H2O2/Fe2+ and the H2O2/UV/Fe2+ processes. Removal of COD and color of approximately 80 and 90% can be achieved by H2O2/UV/Fe2+ processes, respectively. The H2O2/Fe2+ reaction is responsible for approximately 80% removal of both COD and color, the H2O2/UV reaction for 10%, and UV/Fe3+ for the remaining 10%. The removal kinetics of COD and color were consistent with those of H2O2 and Fe2+, respectively. Ferrous ions addition at higher dosage results in the rate of COD removal per unit dosage higher than that of color, whereas the UV irradiation favors color removal more than the COD removal, in terms of rate or rate per unit power. It appears that there is some benefit gained by multi-step addition of Fe2+, but not H2O2. (C) 1999 Elsevier Science B.V. All rights reserved.