Treatment of textile dyeing wastewater using advanced photo-oxidation processes for decolorization and COD reduction

In this study, advanced oxidation processes were applied to the treatment of a textile dyeing wastewater. The effluent presents a dark blue color, with a maximum absorbance peak at 594 nm, alkaline pH (pH = 12.4), high organic contents (COD = 1,400 mg L–1). Experiments were conducted on a lab-scale prototype using UV lamp as light source and pillared natural clay with Fe and Al as catalyst. All the processes examined lead to an effective decolorization and mineralization, but the most efficient process was the photo-Fenton, contributing to 93% decolorization and 88.8% mineralization after 3 h of reaction under UV irradiation. Characteristics of wastewater after treatment were COD below 250 mg L–1, pH 8.5 and uncolored. Thus the resultant water has conditions that are suitable for releasing in public sewage systems.