Determinação de metais, HPAS e ecotoxicidade em amostras de lixiviados de resíduos de pavimentação asfáltica

Abstract

Reclaimed Asphalt Pavement (RAPs) has a variety of organic and inorganic compounds that can interact with the environment and promote deleterious effects on human health. In Brazil, the National Environment Council (CONAMA) Resolution No. 307/2002 classifies this type of waste as class A, which should be primarily reused or recycled as aggregates, and if not possible, should be disposed of in appropriate landfills. However, landfills of class A waste do not have basic waterproofing or drainage system, which can favor the leaching of harmful substances into environmental compartments. In addition, the negligence of the public authorities over the management of RAPs, opens the precedent for clandestine disposal, directly on land. In this context, this study aimed to investigate the toxicity potential of RAPs through metal determination, HPAs and ecotoxicity tests with Daphnia magna indicator organism. Leached extracts and solubilized extract of four samples of RAPs and a sample of hot mix asphalt (HMA) concrete for comparison purposes were analyzed. Regarding metals, Al and Mn were found in the solubilized extract above the maximum value allowed for Annex G of Brazilian Association of Technical Standards (ABNT) NBR 10.004: 2004. For the leached extracts, no sample had concentration above the maximum value allowed by Annex F of cited standard. However, the samples contained concentrations of Cd, Cr, Pb, Ni and Cu, which are on the list of substances that confer toxicity to the residues of Annex C of ABNT NBR 10.004: 2004. For HPAs, two samples of leachate had BaP concentration above the maximum value allowed by Annex F and the other samples had BaP values close to the established limit. In addition, the samples still presented concentration of BaA, BbF, InP and Cri, which compose the annex C of ABNT NBR 10.004: 2004. For the ecotoxicity tests, two solubilized samples indicated acute toxicity to Daphnia magna. According to ABNT NBR 10.004: 2004, the results of this research indicated that two samples of RAPs could be classified as hazardous waste (class I), pointing out that these residues have the potential to leach hazardous substances to the waste. Therefore, the disposal of this type of waste should be carefully evaluated because its composition contains substances that may degrade the environment and human health.