Reuse of textile dyebaths by treatment with advanced oxidation

Abstract

The urgent need to conserve, recycle, and reuse the limited water resources of the earth has forced mankind to research and develop new methods and technologies for treating and managing used waters from process, cooling and/or rinse facilities of industrial applications. This is especially important in textile dyeing and finishing industries, where huge amounts of water are consumed in dyeing and washing/rinsing ofthe fabrics. The purpose of this study was to investigate the reusability of dyebath effluents in a textile batch dyeing process, by a homogeneous advanced oxidation system, involving H20 2 and ferrous sulfate in the presence and absence of UV-light. Synthetic dye bath effluents were prepared using a reactive azo-dye, Procion Red HE-7B, which was selected as a model compound for its wide use in the industry. Effectiveness of the system was tested by monitoring the degree of color and total organic carbon degradation. Parameters such as chemical oxygen demand and total dissolved solids were also monitored. Reusability of the treated water was tested in a dyehouse with various azo dyes. Under the experimental conditions employed, it was found that complete color removal and 71 % total organic carbon degradation is possible in 20 min of UV irradiation. The treated effluent was found to be reusable in cotton batch dyeing, yielding satisfactory dye quality on the fabric. Estimated cost of reusing dyebath effluents after treatment with the proposed technique was found to be 1.54 per m3 • The corresponding cost of using commercial water supply was estimated to be 2.42 per m3.