PARÂMETROS ECOTOXICOLÓGICOS DE EFLUENTES DA INDÚSTRIA DE LATICÍNIOS E DE UM ATERRO SANITÁRIO

Abstract

The present study aimed to evaluate the toxicological parameters of two different effluents, using bioindicators, focusing on the quality of the aquatic environment and treated effluents. The first effluent analyzed came from the dairy industry, before any treatment, and was subjected to bioassay using Lactuca sativa (lettuce) seeds. The phytotoxic test with the seeds revealed that the effective concentration (EC50) for this effluent was estimated at 48%, indicating a present toxicity, but not significantly high. At dilutions of 0.25% and 0.5%, the effluent showed stimulating effects on root elongation. However, at dilutions above 10%, phytotoxic effects were observed due to the presence of chloride. The second evaluated the efficiency of tertiary treatment of landfill leachate using Wetland lagoons through the analysis of bioindicators at two different trophic levels: vegetables (Lactuca sativa and Allium cepa) and microcrustaceans (Daphnia magna). Effluent samples were collected at two points: before Wetland treatment (AW) and after Wetland treatment (PW) before being discharged into the receiving body. The bioassay with Lactuca sativa revealed that the effluent collected from AW showed phytotoxicity, with inhibition of seed germination at a dilution greater than 10%. The effluent collected PW showed germination in 100% of the seeds, but inhibition occurred at dilutions above 30%. To evaluate the effects of leachate on mitotic division, raw effluent without dilution in Allium cepa was used, with cellular degeneration being observed in the AW effluent and stimulation of mitotic division in the PW effluent. The test with Daphnia magna revealed that the effective concentration that results in 50% mortality (EC50) for the AW effluent is obtained at a dilution between 1% and 2%, while for the PW effluent, the EC50 is close to 100%. These results indicate that the Wetland system is effective in reducing the toxicity of the effluent, since, when released into the receiving body, it is diluted in the mixing zone.