Pharmaceuticals in Belgrade's wastewater: Impact on surface waters and environmental risk assessment

In the Belgrade region, direct discharges of untreated wastewater into the Sava and Danube Rivers have a detrimental impact on water quality. This study investigates this impact by investigating the presence of pharmaceuticals in Belgrade's wastewater and corresponding surface water, alongside the associated environmental risk. A highly sensitive and selective LC-MS/MS method was developed, validated and applied to the analysis of water samples. Thirteen out of seventeen target pharmaceuticals were detected in wastewater, while nine compounds were found in surface water, with diclofenac reaching the highest concentration (1.1 ?g L-1). Metoprolol, carbamazepine, and diclofenac were the most prevalent in both wastewater and surface water samples. Risk assessment indicated that diclofenac and azithromycin posed a high environmental risk (RQ > 1), while mixture toxicity assessment suggested a cumulative hazard at all sampling sites. Additionally, the study evaluated pharmaceutical removal efficiencies in two wastewater treatment plants in Serbia, revealing variable efficiencies and even negative removal rates for some compounds, highlighting the inadequacy of conventional treatment plants in effectively eliminating these substances. The results emphasize the urgency of regulatory actions and the need for adequate treatment technologies to reduce pharmaceutical pollution in aquatic environments.