Occurrence and fate of amisulpride, sulpiride, and lamotrigine in municipal wastewater treatment plants with biological treatment and ozonation

⿢A tailored non-target screening approach helps to identify new contaminants.⿢Amisulpride, sulpiride and lamotrigine represent indicators for treated wastewater.⿢Cleavage of lamotrigine-N2-glucuronide increases secondary effluent concentrations.⿢N-Oxides may represent relevant ozonation products. This study examines the transformation and removal of the atypical antipsychotics amisulpride and sulpiride and the anticonvulsant lamotrigine in municipal wastewater treatment plants (WWTPs). Amisulpride, sulpiride and lamotrigine were selected using a tailored non-target screening approach. In WWTPs, lamotrigine concentrations increased from 1.1 to 1.6μg/L while sulpiride and amisulpride exhibited similar concentrations, up to 1.1μg/L and 1.3μg/L, respectively. It was found that N2-glucuronide conjugates of lamotrigine were cleaved to form lamotrigine. Both lamotrigine and amisulpride were detected in groundwater with a concentration of 0.07μg/L. Sulpiride was identified but not quantified. This demonstrates that amisulpride, sulpiride and lamotrigine might be used as indicators for treated wastewater in raw waters used for drinking water production. Furthermore, it could be shown that all three pharmaceutical compounds are efficiently oxidized by ozonation, leading mainly to N-oxide oxidation products. No significant removal of the N-oxides of amisulpride, sulpiride and lamotrigine was observed in the bench-scale biodegradation experiments with activated sludge. This indicated their high biological persistence. Therefore, N-oxides might be appropriate as indicators for post-ozonation as a major technology for the advanced treatment of secondary effluent.