Mitigation of emerging contaminants by full-scale horizontal flow constructed wetlands fed with secondary treated wastewater

•We studied the removal of emerging contaminants (ECs) in 12 constructed wetlands.•HFCWs were able of removing 43% of ECs on average.•The acute toxicity (EC50) on Daphnia magna dropped by more than 60%.

The discharge of emerging contaminants (ECs) from wastewater treatment plants into the aquatic environment is a matter of great importance due to the potential adverse effects that they can exert on aquatic biota. This study assesses the capacity of 12 full-scale horizontal-flow constructed wetlands (HFCWs) (18,000 m2 in total) used as tertiary treatment to remove 16 ECs from secondary treated wastewater (423,500 PE). Benzotriazole, 5-methylbenzotriazole, ketoprofen, and diclofenac were the most abundant (>2000 ng L−1 on average) in the secondary treated wastewater effluent. EC removal levels ranged from no removal to 92%, with an average removal of 43%. A significant relationship was observed between the removal of ECs in the HFCWs and their log Kow and molecular weight. The HFCWs were able to attenuate the predicted ecotoxicological effects of ECs on aquatic biota (Daphnia magna) by 66%. This study indicates that HFCWs are suitable for removing ECs from WWTP effluents and, therefore, reduce the ecotoxicological effects associated with pollutant discharges.

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