Pharmaceutical Micropollutants in Wastewater: A Case Study of the Mascara WWTP (Algeria)

Pharmaceuticals are emerging contaminants of global concern, but their occurrence and removal in semi-arid regions such as Algeria remain poorly documented. This study provides the first systematic evaluation of pharmaceutical and physicochemical parameters in two wastewater treatment plants (WWTPs) in Mascara: an activated sludge system (WWTP-1) and an aerated lagoon system (WWTP-2). Ten pharmaceuticals of different therapeutic classes were quantified using UPLC-HR-QTOF-MS in influent, effluent, and sludge samples, and removal efficiencies were compared using ANOVA and Principal Component Analysis (PCA). WWTP-1 showed higher efficiency, with >90% removal of COD, BOD5, and ammonium, and near-complete elimination of sulfamethoxazole (99.9%) and atenolol (94%). In contrast, WWTP-2 achieved only moderate reductions (69% COD, 51% BOD5) and low pharmaceutical removal, with negative efficiencies for persistent compounds such as carbamazepine, diclofenac, and ibuprofen. Weak correlations between macro- and micropollutants indicated that traditional indicators cannot predict pharmaceutical behavior. This work is the first to integrate physicochemical monitoring, pharmaceutical profiling, and multivariate analysis in Algerian WWTPs. The findings highlight the limitations of conventional treatment in semi-arid conditions and provide a critical baseline for adopting advanced technologies to mitigate pharmaceutical pollution in North Africa.