The ability of UWWTP to remove NSAIDs: Impact on water quality in the Odra River Czech Republic concerning incoming European legislation

• The urban wastewater treatment plant in Ostrava effectively removes selected drugs. • Statistical analysis confirms seasonal variations of diclofenac and ibuprofen. • 8.5 kg and 30.5 kg of ibuprofen and diclofenac were discharged throughout the year. • First data on ibuprofen and diclofenac concentrations in the Odra River, Czechia. Increased consumption of pharmaceuticals has resulted in their detection in wastewater. If wastewater treatment plants (WWTPs) fail to eliminate these substances adequately, they can seep into the environment, posing potential risks. As non-steroidal anti-inflammatory drugs (NSAIDs) belong to the pharmaceuticals most frequently examined in wastewater, this study aimed to monitor wastewater from the municipal wastewater treatment plant in Ostrava (UWWTP) over the course of a year, specifically assessing how the presence of these substances in discharged wastewater could contaminate the Odra River. To further understand the impact of NSAIDs, we evaluated the effectiveness of UWWTP technology in removing the following selected drugs: diclofenac (DCF), ibuprofen (IBU), naproxen (NAP) and ketoprofen (KET) - as well as their main metabolites: 4′-hydroxydiclofenac (hydroxyDCF), carboxyibuprofen (carboxyIBU), desmethylnaproxen (desmethylNAP), and ketoprofen glucuronide (glucuronideKET). Wastewater samples were collected at both the inflow and outflow of the urban wastewater treatment plant (UWWTP) Ostrava from October 2022 to September 2023. The analysis was performed using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The concentrations of the monitored substances at the UWWTP inflow varied significantly, ranging from 79 ng/L to 112,125 ng/L, with the highest levels detected for ibuprofen (IBU), diclofenac (DCF), and their metabolites. The UWWTP demonstrated impressive treatment efficiency for IBU, exceeding 98%, while for DCF, it ranged between 56% and 87%. Building on these findings, a monitoring campaign was initiated along the Odra River to evaluate the concentrations of IBU and DCF - substances that had not been measured before. Water samples were taken from various locations along the Odra River from October to November 2023 and analyzed using the same methodology as the wastewater samples. The results indicate that, in line with the proposed environmental quality standards (EQS), IBU and DCF do not pose a significant contamination risk to the Odra River.