Assessment of plant-driven removal of emerging organic pollutants by duckweed

Constructed treatment wetlands have the potential to reclaim wastewaters through removal of trace concentrations of emerging organic pollutants, including pharmaceuticals, personal care products, and pesticides. Flask-scale assessments incorporating active and inactivated duckweed were used to screen for plant-associated removal of emerging organic pollutants in aquatic plant systems. Removals of four of eight pollutants, specifically atrazine, meta-N,N-diethyl toluamide (DEET), picloram, and clofibric acid, were negligible in all experimental systems, while duckweed actively increased aqueous depletion of fluoxetine, ibuprofen, 2,4-dichlorophenoxyacetic acid, and triclosan. Active plant processes affecting depletion of experimental pollutants included enhancement of microbial degradation of ibuprofen, uptake of fluoxetine, and uptake of degradation products of triclosan and 2,4-dichlorophenoxyacetic acid. Passive plant processes, particularly sorption, also contributed to aqueous depletion of fluoxetine and triclosan. Overall, studies demonstrated that aquatic plants contribute directly and indirectly to the aqueous depletion of emerging organic pollutants in wetland systems through both active and passive processes.