Catalytic thermal treatment (catalytic thermolysis) of textile dyeing effluent

Abstract

During the production of textiles a large amount of wastewater is generated that contains high organics load and color appearance. If it is directly (untreated) discharged into any water-receiving body then it gets fully contaminated, hence its proper treatment is required. The present study deals with the treatment of textile dyeing effluent (TDE) using catalytic thermolysis (CT) for the reduction of color and COD reduction with the help of CuO as a catalyst. The catalyst (CuO) was prepared successfully on the laboratory scale. The CuO preparation is done by alkali precipitation of copper sulfate followed by drying and calcination. Catalyst is characterized in detail including X-ray diffraction, SEM, and TEM analysis. CT treatment of TDE was carried out in a 0.5 dm3 thermolysis batch reactor using CuO as a catalyst at different pH (2.4–10.4), temperatures (70 °C–115 °C), and catalyst loadings (1.5–5.5 g/dm3). The maximum 72 % COD reduction was achieved at the optimum condition of 70 °C temperature, catalyst loading of 1.5 g/dm3, and 4.4 pH. The residues obtained after CT were characterized by TGA, TDA, and TG. In addition, settling characteristics were also observed for CT-treated sludge at different temperatures. CT is a novel treatment technique to treat highly polluted wastewater. During the CT treatment, the addition of chemicals is not required and it has good removal efficiency. Further CT-treated sludge has good heating value hence it can be used as an industrial fuel. In other words, no secondary pollutants are generated during the CT process.