Microplastic removal and risk assessment framework in a constructed wetland for the treatment of combined sewer overflows

• DOI: 10.1016/j.scitotenv.2024.175864
• Publication Date: 2024-08-29T06:25:19Z
• Authors: Chiara Sarti; Alessandra Cincin...; Riccardo Bresciani; Anacleto Rizzo; David Chelazzi; Fabio Masi
• Keywords: Combined sewer; Constructed wetland; Filtration (mathematics)

Combined sewer overflows (CSOs) release a significant amount of pollutants, including microplastics (MPs), due to the discharge untreated water into receiving bodies. Constructed Wetlands (CWs) offer promising strategy for CSO treatment and have recently attracted attention as potential solution MP mitigation. Nevertheless, limited research on dynamics within events removal performance in full-scale CW systems poses barrier this frontier application. This aims address both these knowledge gaps, representing first investigation multi-stage CSO-CW removal. The study presents one year seasonal data from upstream WWTP Carimate (Italy), evaluating correlation abundance with different quality/quantity parameters associated ecological risks. results show clear trend abundance, which increases rainfall intensity. strong between concentration, flow rate, total suspended solids (TSS) validates flush phenomenon hypothesis its impact during CSOs. Chemical characterization identifies acrylonitrile-butadiene-styrene (ABS), polyethylene (PE), polypropylene (PP) predominant polymers. vertical subsurface (VF) stage showed rates ranging 40 % 77 %. However, unexpected increase concentrations after second free surface (FWS) suggests stochasticity hydraulic characteristics units diverse effects retention. These confirm filtration main retention mechanism systems. risk assessment indicates high-risk category most samples, mainly related frequent presence ABS fragments. contribute current understanding MPs released by CSOs provide insights large-scale system, suggesting requirement further attention.