Toxicity of textile effluents treated by electron beam technology

Abstract

The textile industry uses expressive amount of water during the production and generate effluents that contain residuals of dyes, surfactants, peroxides, acids and salts, and toxicity. In addition, the textile effluents are commonly colored, because the dyes used in fibers dyeing usually have low fixation and high solubility. Many of the mentioned products are not easily removed, requiring additional treatment steps. Advanced Oxidative Processes, such as electron beam irradiantion (EBI), can be a good alternative to reduction of organic pollutants from effluents. Therefore, studies on these contaminants in aquatic environment are important for assessing their impacts on ecosystems and water quality. The objective of this study was to evaluate the toxicity of textile effluents treated with EBI. The doses of 2.5 kGy and 5.0 kGy were used. The toxicity assays were performed with Daphnia similis organisms, exposed to samples during 48 hours, and the results expressed by EC50 (median effective concentration). For the textile effluent, EC 50% values ranged from: 2.95 ±0.13 (raw effluent) until 20.90 ±1.48 (irradiated effluent, at 5kGy). The EBI treatment was effective for toxicity reduction, with efficiency higher than 60% (2.5 kGy) and 80% (5.0 kGy). The study of organic and inorganic contaminants, presents in these effluents, demonstred EC 50 values below 5%. These results demonstrate high toxicity of contaminants from textile effluents for aquatic organisms (D. similis, cladocera). Similar data was observed for the raw effluent. These values are relevant for thinking radiation as a possible technology for such a type of effluent.