Résumé
•EO tested on effluents with organic matter concentrations up to 1000 times higher than micropollutants.•BDD EO effective for CBZ, DIU, and PFOS despite organics, demonstrating robustness and selectivity.•CBZ removal exceeded 90 % and DIU above 80 %, whereas PFOS showed partial elimination.•Moderate energy demand and reduced toxicity support EO as a polishing step aligned with Directive (EU) 2024/3019 objectives.
This study investigated the electro-oxidation (EO) of three priority micropollutants: carbamazepine (CBZ), diuron (DIU), and perfluorooctane sulfonate (PFOS), in secondary-treated wastewater using boron-doped diamond (BDD) anodes. Although BDD anodes generate strong, largely non-selective oxidants; however, their performance at environmentally relevant concentrations, across different classes of micropollutants and under realistic organic-matter loads remains insufficiently characterized, especially for fluorinated and other recalcitrant contaminants. The selected compounds represent persistent pollutants with contrasting physicochemical properties and regulatory relevance (EU 2024/3019), which requires ≥ 80% CBZ between raw wastewater and the treated effluent. A four-factor central composite design (current density 10.7–33.0 mA/cm2, electrolysis time 14–56 min, COD 0.9–29 mg/L, influent concentration 0.3–8.7 µg/L; pH 7–8; flow 40 L/h) was used to quantify the influence of operating conditions on removal efficiency, energy demand and by-product formation. CBZ and DIU were efficiently removed under most conditions (> 98%), while PFOS elimination reached up to 93% under high-time/high-current regimes. At environmentally relevant influent levels (1–2 µg/L), removals of 92% (CBZ), 80% (DIU) and 41% (PFOS) were achieved with a moderate and conceivable energy demand (3.35 kWh/m3). Dissolved organic matter slightly reduced degradation rates but did not prevent effective pollutant targeting. Acute toxicity assays revealed a transient increase occurring alongside the formation of primary transformation products, followed by a decline at extended treatment durations, consistent with the progressive oxidation of toxic intermediates. Overall, the study provides a quantitative, multi-response evaluation of BDD EO under realistic wastewater conditions, clarifying operational limits, energy–performance trade-offs, and transformation-product dynamics relevant to its implementation as an advanced polishing step.
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