Effect-based assessment of laboratory- and full-scale advanced wastewater treatment using combined ozonation and powdered activated carbon

The use of advanced treatment processes such as ozonation and activated carbon filtration in full-scale systems is showing promising results worldwide for removing micropollutants (MPs) and reducing ecotoxicological effects from wastewater (WW). In this study, a combined advanced treatment process consisting of ozonation followed by powdered activated carbon (PAC) filtration was evaluated at laboratory-scale and full-scale in a municipal wastewater treatment plant (WWTP) using the same WW collected during a single sampling campaign. A battery of in vitro assays was applied to assess the elimination of toxic effects in both systems. The laboratory-scale treatment operated at a higher ozone dose (0.7 mg O3/mg DOC (dissolved organic carbon)) than the full-scale system (0.1 mg O3/mg DOC) and achieved higher removal efficiencies for baseline toxicity, estrogenic activity, androgenic activity, and dioxin-like activity. Baseline toxicity removal reached 100% in the laboratory-scale treatment compared with 92% at full scale. Estrogenic activity removal was 100% in the laboratory-scale treatment but remained substantially lower at full scale with 62%. The findings indicate that ozone dose is a major explanatory variable influencing treatment performance and emphasize the importance of optimized ozone dosing and post-treatment processes to minimize residual toxicity and transformation products.