Use of ARP industrial waste in the remediation of cadmium, lead and zinc in contaminated sediments

The most common contaminants in the earth’s crust are heavy metals. Remediation is a technique to immobilize, remove, or detoxify these metals in contaminated environments. However, after decades using conventional remediation techniques, new scientific findings indicate that these remediation operations can promote adverse impacts. Given this perspective, a sustainable remediation approach that minimizes environmental, social, and economic impacts has been growing. The objective of this work was to evaluate the chemical immobilization provided by a steel mill industrial waste from the Acid Recovery Plant (ARP) as an alternative to remediate sediments affected by cadmium, lead and zinc. The experiment consisted in adding increasing doses of an ARP industrial residue, consisting mostly of iron oxide, to sediment samples contaminated by a metallurgical industry. After the incubation period, samples from each treatment were removed and submitted to simple extractions (water, acetic acid, DTPA and sodium nitrate) and total pseudo digestion (nitro-perchloric) to determine the bioavailability of Cd, Pb and Zn. The application of the ARP residues provided the formation of complexes associated with the most stable chemical fractions, such as the fraction associated with Fe oxides (F4) and the residual fraction (F5). Treatment with 5% ARP residue was sufficient to reduce the solubility of Cd, Pb and Zn in the sediment studied. Chemical containment proved to be a promising alternative for minimizing the impact of potentially toxic elements (PTEs) in contaminated soils and sediments, as well as being viable from a sustainable point of view.