Occurrence, removal, and ecological risk of emerging contaminants in major wastewater treatment plants across the United Arab Emirates

Emerging contaminants (ECs) have received growing global attention. Yet, data on the distribution and fate of pharmaceuticals, personal care products, and pesticides in wastewater generated in the United Arab Emirates (UAE) remain limited. This study is the first to investigate the occurrence and removal efficiency of 48 ECs across major wastewater treatment plants (WWTPs) in the five northern emirates (Sharjah, Umm Al Quwain, Fujairah, Ras Al Khaimah, and Ajman). The study revealed that a total of 14 compounds exceeded concentrations previously reported in other regions, with acetaminophen (19,682.85 ± 10,474.19 ng/L), caffeine (17,487.37 ± 4512.90 ng/L), and salicylic acid (8786.81 ± 5242.74 ng/L) showing the highest levels in influent wastewater. Certain compounds, such as N, N-diethyl-meta-toluamide and lincomycin, exhibited marked temporal fluctuations over the six months. This underscores the need for ongoing seasonal and local monitoring. In effluent wastewater, compounds like acetaminophen, caffeine, furosemide, sulfadiazine, and methylparaben consistently showed high removal efficiencies (75.60–100.00%). In contrast, some demonstrated frequent negative removal efficiencies. This includes venlafaxine, carbamazepine, and acetamiprid. Distance matrix analysis showed that Fujairah and Ajman were the most similar, whereas Umm Al Quwain and Ras Al Khaimah were the most distinct in treatment performance. Risk quotient values for compounds detected in WWTP effluents ranged from 4.54 × 10−6 (cimetidine) to 5.70 (diclofenac), representing negligible to high environmental risk. Notably, diclofenac, gemfibrozil, and azoxystrobin posed ecological risks to all three test organisms. Collectively, these results emphasize the necessity of monitoring ECs and support the establishment of regulations that advance a One Health framework, protecting human, animal, and ecosystem health.