Fate of pharmaceutical residue in two Romanian rivers receiving treated water: Occurrence, distribution and risk assessment

This study presents the first set of data on the removal of proton pump inhibitors (PPIs) and histamine H2 receptor antagonists (HRAs) and their transformation products in two Romanian wastewater treatment plants (WWTPs), as well as the impact of these organic pollutants on freshwater receiving effluents. The research investigated eight target pharmaceuticals and three metabolites using a newly developed and validated Liquid Chromatography - Mass Spectrometry (LC-MS/MS) method. The combined determination had a range of quantification limits varying from 0.13 ng/L to 0.18 ng/L for surface water and from 0.28 ng/L to 0.43 ng/L for wastewater. All analytes except cimetidine and 5-hydroxy-omeprazole were identified in water samples. The study found similar overall removal efficiencies for both WWTPs (43.2 % for Galati and 51.7 % for Ramnicu-Valcea). The research also showed that ranitidine and omeprazole could pose a low to high ecological risk to aquatic organisms. The findings suggest that the treatment stages used in the two Romanian WWTPs are insufficient to remove the target analytes completely, leading to environmental risks associated with the occurrence of pharmaceutical compounds in effluents and freshwater.