Abstract This study investigates the co-occurrence and concentrations of emerging contaminants in urban sewer overflows. Combined sewer overflows (CSOs) contained total PFAS concentrations up to 320 ng/L (mean: 33.2 ng/L), with post-TOP assay analysis indicating significant contributions from precursor compounds. The tire wear product, 6-PPD-Q, acutely toxic to aquatic life, was detected in CSOs at concentrations up to 895 ng/L (mean: 242 ng/L), directly linked to urban runoff. Various microplastic polymers were also frequently found in both CSOs and sanitary sewer overflows (SSOs), underscoring widespread plastic pollution. High-rate treatment (HRT) systems employing chlorination (for CSOs) and UV disinfection (for SSOs) effectively reduced 6-PPD-Q concentrations, but showed limited PFAS removal, with evidence suggesting precursor transformation into more persistent forms during treatment. Only partial microplastic removal was observed in the SSO treatment scenario, indicating a need for more effective strategies employing biological or physicochemical treatment. These findings necessitate targeted removal technologies to protect aquatic ecosystems and provide valuable baseline data for urban water management.
Butzlaff et al. (Thu,) studied this question.