Ecotoxicological Evaluation of Paint Industrial Effluent Post-Treated with Fenton-Type Coagulation

Effluents from the paint industry released into water bodies without treatment contain a large load of organic matter, metals, suspended solids, and pigments that are responsible for the contamination of aquatic ecosystems. Therefore, in addition to conventional treatment processes, advanced processes are needed to reduce harmful effects on the environment, with advanced oxidative processes (AOPs) being an alternative for treating these wastewaters. Fenton-type coagulation is a combination of the coagulation process and Fenton-type (AOP) that replaces traditional reagents (H₂O₂ + Fe²⁺) with peracetic acid + Fe³⁺ in the attempt at reduced toxicity and improved efficiency in the removal of contaminants. This study aimed to obtain ecotoxicological data on effluents from the paint industry, raw and post-treated with Fenton-type coagulation, using the planarian species Girardia tigrina as a bioindicator of contamination. The acute toxicity bioassay results were not statistically significant. Chronic toxicity tests demonstrated few toxic effects on organisms exposed to the treated effluent. The locomotion of the planarians was reduced in the raw effluent. Exposure to raw effluent also negatively affected the development and reproductive parameters of the organisms, resulting in delayed regeneration of the blastema, photoreceptors, and auricles, in addition to a reduction in the number of cocoons and fertility, which did not occur when planarians were exposed to the treated effluent. The results showed that treating paint effluent with Fenton-type coagulation reduces effluent toxicity.