A Comparative Study of Ozone and Ultraviolet Light/Hydrogen Peroxide for Decolorizing Textile Dyeing Waste Water

Abstract

Decolorizing textile mill spent dyebath effluents with UV radiation in the presence of hydrogen peroxide (UV/peroxide) and with ozone was investigated. Direct, disperse, and acid dyes with known chemical structures were decolorized. The dyes at concentration levels typically present in mill waste water were treated with low intensity UV radiation in the presence of hydrogen peroxide. Small amounts of hydrogen peroxide accelerated dye decolorization with the low intensity UV radiation. Both ozone and UV/peroxide treatment was effective in decolorizing water soluble dyes such as acid and direct dyes. Water insoluble disperse dyes reacted much more slowly than water soluble dyes when treated with either UV/peroxide or ozone. Reaction rates of the dyes with ozone were greater than with UV/peroxide under the conditions used in this study. Electrical power and chemical cost to decolorize water soluble dyes with either ozone or UV/peroxide are similar. For disperse dyes, estimated treatment cost was higher with the UV/peroxide system than with ozone. Data was not available to estimate capital and other operating costs for the decolorization systems.