Investigation of organic micropollutants in urban wastewater and the feasibility of reusing treated wastewater for irrigation purposes

Wastewater treatment plants (WWTPs) are a major source of organic micropollutants (OMPs) in aquatic environments, as conventional treatments fail to achieve complete contaminant removal, posing risks to aquatic ecosystems. Although the recent European Directive on wastewater represents significant progress in regulating key pollutants in urban wastewater, the overall regulatory framework remains insufficient. This study aimed to monitor a wide range of pharmaceuticals and pesticides in influent (IWW) and effluent (EWW) wastewater from three WWTPs in Eastern Spain, assess environmental risks, and evaluate the feasibility of reusing EWW for soil irrigation. Analyses were performed using liquid chromatography–tandem mass spectrometry with numerous isotope-labeled internal standards, ensuring excellent sensitivity and selectivity. The reliability of the data was confirmed through quality control (QC) sample analysis, with most recoveries ranging between 70 % and 120 %. A recent multicriteria assessment based on contaminant occurrence, persistence, bioaccumulation, and toxicity facilitated the identification and prioritization of those posing the greatest risk to aquatic environments. A similar approach was applied to assess the feasibility of using EWW as reclaimed water for soil irrigation. Our findings revealed significant concentrations of OMPs in both IWW and EWW, with varying removal efficiencies across the three WWTPs. Among the 78 compounds analyzed, diclofenac, losartan, tramadol, and chlorpyrifos were identified as the most concerning. These results highlight the urgent need for improved wastewater treatment processes to mitigate environmental risks and support the safe reuse of treated effluents for irrigation. • Wide monitoring of pharmaceuticals and pesticides in three WWTPs. • EU regulations propose stricter controls on WWTPs to minimize contaminants. • Most contaminants were poorly or partially removed in WWTPs. • A risk assessment by OPBT approach was used to prioritize contaminants of most concern. • Improved wastewater treatments are needed for effluents reuse in irrigation.