Due to the high consumption and incorrect disposal of pharmaceutical active compounds (PhACs), they are recognized as contaminants of emerging concern. Wastewater treatment plants (WWTPs) may be inefficient in removing PhACs, therefore discharging them into surface waters. The removal efficiencies of five WWTPs located in the south of Portugal (Alentejo) were evaluated in 2020. Twenty-six PhACs were analyzed in wastewater influents, effluents, and surface waters, upstream and downstream of the WWTPs by solid-phase extraction (SPE) and ultra-performance liquid chromatography coupled with tandem mass detection (UPLC–MS/MS). The most representative PhACs in influents were acetaminophen, caffeine, naproxen, ibuprofen, and diclofenac with minimum-maximum concentrations of 49–225 µg/L, 26–46 µg/L, 5.9–13 µg/L, 5.2–22 µg/L, and 1.3–2.5 µg/L, respectively. For effluents, it was acetaminophen, caffeine, and diclofenac with minimum-maximum concentrations of 0.054–7.8 µg/L, 0.084–4.8 µg/L, and 0.28–3.3 µg/L, respectively. The highest removal efficiencies were observed for acetaminophen, sulfadiazine, cortisone, testosterone, metoprolol, and propranolol (100%). The lowest removal efficiencies were observed for carbamazepine (2.7%) and diclofenac (−13.2%). The risk quotient of sulfamethoxazole and diclofenac were higher than 1 for receiving waters, indicating they probably pose high risks to aquatic organisms.
