Climate-Resilient and Sustainable Soil Remediation: Hydrocycloning for Metal Removal in Flood-Prone Brazilian Region

Soil contamination by heavy metals from industrial and mining activities poses a significant global threat to both environmental and human health, particularly in brownfields—abandoned or underutilized industrial areas that frequently accumulate pollutants. Climate change exacerbates this issue by intensifying extreme events such as floods, which can enhance contaminant mobility and compromise the reliability of conventional remediation methods. This study evaluated the in situ application of a sustainable soil washing technique based on hydrocycloning at a contaminated site in Canoas (Porto Alegre, Brazil), a flood-prone area heavily impacted by the 2024 climate disaster. The method physically separates heavy metals by concentrating them into a fine, high-contamination fraction for controlled disposal. Approximately 3019 m3 of soil was treated, recovering 93.4% of the material (coarse and fine sand) for potential reuse and isolating only 6.6% (200 m3) as hazardous waste. Chemical analyses confirmed that the recovered fractions complied with regulatory limits for heavy metals, while contaminants were effectively retained in the sludge and safely disposed of through landfills. During the April–May 2024 flood events, although the site was inundated, no significant erosion of the backfilled material was registered. The results support hydrocycloning-based soil washing as a robust and climate-resilient approach to adaptive remediation in contaminated environments.