Ecotoxicity of Sludges Generated by Textile Industries: A Review

Abstract

Textile industries consume a large amount of water and use toxic products in its processes. Consequently, they produce and release large volumes of effluents, which, treated, generate great amount of sludge. The final disposal of this sludge remains a challenge, and its ecotoxicological assessment is an important parameter to minimize its impacts. This article reviewed the ecotoxicological tests that have been employed to evaluate the hazard of such sludge. There are few papers in the literature on this issue, as well as a lack of consensus about sample preparation procedures and test organisms to be used. The test organisms most employed are higher plants, bacteria and aquatic organisms. Only one article used earthworms and one, mammals. Composting was efficient for reduction or elimination of the phytotoxicity of textile sludge. Both Daphnia magna and Vibrio fischeri showed adequate sensitivity for sludge acute toxicity evaluation. The endpoint genotoxicity using the Salmonella/ microsome assay seems to be important, because most of the obtained results were positive. More studies are needed to understand the applicability of algae, earthworms and mammals. Efforts are being made to establish a reliable battery of bioassays for ecotoxicological evaluation of such waste.