| Summary: | <p>Abstract</p> <p>Background</p> <p>The fate of 14 antidepressants along with their respective <it>N</it>-desmethyl metabolites and the anticonvulsive drug carbamazepine was examined in a primary sewage treatment plant (STP) and following advanced treatments with ozone (O<sub>3</sub>). The concentrations of each pharmaceutical compound were determined in raw sewage, effluent and sewage sludge samples by LC-MS/MS analysis. The occurrence of antidepressant by-products formed in treated effluent after ozonation was also investigated.</p> <p>Results</p> <p>Current primary treatments using physical and chemical processes removed little of the compounds (mean removal efficiency: 19%). Experimental sorption coefficients (K<sub>d</sub>) of each studied compounds were also calculated. Sorption of venlafaxine, desmethylvenlafaxine, and carbamazepine on sludge was assumed to be negligible (log K<sub>d</sub> ≤ 2), but higher sorption behavior can be expected for sertraline (log K<sub>d</sub> ≥ 4). Ozonation treatment with O<sub>3</sub> (5 mg/L) led to a satisfactory mean removal efficiency of 88% of the compounds. Screening of the final ozone-treated effluent samples by high resolution-mass spectrometry (LC-QqToFMS) did confirm the presence of related <it>N</it>-oxide by-products.</p> <p>Conclusion</p> <p>Effluent ozonation led to higher mean removal efficiencies than current primary treatment, and therefore represented a promising strategy for the elimination of antidepressants in urban wastewaters. However, the use of O<sub>3</sub> produced by-products with unknown toxicity.</p>
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