Pharmaceutical residues in wastewater treatment plants in Poland: Removal efficiency and risk assessment

Conventional wastewater treatment plants (WWTPs) are the largest sources of pharmaceuticals and their metabolites in surface waters. To ascertain which pharmaceuticals are removed in WWTPs and which are not, this study comprehensively examines the presence and removal efficiencies of 88 pharmaceutical compounds in WWTPs employing various treatment technologies in Poland (central Europe). The analysis was performed using a liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Of these 88 compounds 49 were quantified in influents and 44 in effluents, with caffeine exhibiting the highest influent concentration of 185 μg/L. Overall, among the 88 pharmaceutical compounds analyzed, a substantial share was effectively removed, although the efficiency varied widely among compounds. Notably, caffeine, paracetamol, and paraxanthine demonstrated almost complete removal, while lamotrigine exhibited significantly negative removal rates, highlighting challenges in its treatment and effluent contamination in WWTP. The highest concentrations found in effluent were noted for tetracycline (5.6 μg/L), followed by iohexol (5.21 μg/L), and carbamazepine (4.73 μg/L). We therefore conclude that effluents contain a variety of pharmaceuticals, primarily those resistant to wastewater treatment processes, as well as trace amounts of degradable substances that may not have undergone complete transformation. Among these drugs, valsartan, detected in effluent samples, posed the highest human health risk, particularly for children, as indicated by its age-dependent human risk quotient (HRQ) exceeding the safety threshold. From an ecological perspective, caffeine and sulfamethoxazole quantified in effluent samples pose significant threats to algae, with environmental risk quotient (ERQ) values reaching 34.67 and 3.38, respectively. This work highlights that conventional WWTPs are inadequately designed to eliminate all emerging contaminants like pharmaceutical compounds in wastewater, leading to transferring those compounds via effluent to surface waters. There is consequently an urgent need to develop advanced wastewater treatment technologies to address the persistent issue of pharmaceutical contaminants, ensuring environmental and public health protection.