Evaluation of selected operational parameters for the decolorization of dyefinishing wastewater using UV/ozone

To meet the effluent true color regulation of 550 ADMI (American Dye Manufacturers Institute) units in Taiwan, sodium hypochlorite (NaOCl) is currently added to bio- or chemical-treated wastewater for decolorization. This study examined some operating parameters for treating effluent from the biological and chemical coagulation units of a dye-finishing wastewater treatment plant using an ultraviolet (UV)/ozone technique to achieve effluent regulation of 550 ADMI. Experimental results reveal that effluent ADMI values could be reduced from approximately 4,000 to 200 ADMI in an hour using the UV/ozone technique. The findings of this investigation also indicate that the proposed UV/ozone treatment scheme has potential for development into an environmentally friendly decolorization approach for dye-finishing wastewater treatment.