Efficient phytoremediation of first-flush storm water using an innovative constructed wetland: a pilot-scale study towards sustainable water reuse

Phytoremediation for wastewater treatment is a sustainable and cost-effective alternative to traditional methods. This study focuses on treating First-Flush StormWaters (FFSWs), which carry contaminants from urban surfaces, causing water or soil pollution. The performance of an innovative Nature-Based Solution (NBS), using a Hybrid-flow Constructed Wetland (HCW), was tested at a pilot scale to meet quality standards for reusable wastewater. The aquatic macrophytes employed in the HCW Arundo donax, Phragmites australis and Juncus acutus were previously selected by means of a pot phytotoxicity experiment using a synthetic FFSW prepared ad hoc. The HCW remediation efficacy was evaluated both on the synthetic FFSW and real one collected from an industrial hardstanding. A significant pollutant removal (50–100%), for both FFSWs, was obtained after just 72–96 h of their recirculation in the HCW; in addition, a significative reduction of the total bacterial count was observed after their treatment in the HCW. The innovative multi-layered filter beds of the HCW effectively remediated FFSW to meet reuse standards. Additionally, the HCW significantly reduced the required surface area for optimal water remediation by five times per Inhabitant Equivalent, addressing a key limitation for widespread use of such Nature-Based Solutions in wastewater treatment.