An evaluative mode for assessing the fate and effects of contaminants in engineered wetlands

To investigate the potential of engineered wetlands to remove contaminants from wastewaters, a steady-state and temporal multimedia model was developed for a free water surface design. The model estimates contaminant fate throughout wetland media, assesses the potential for bioaccumulation, and evaluates ecological risk using relevant toxicological endpoints (i.e. EC5). Illustrative examples for pyrene, arsenic, a naphthenic acid, and a chemical universe defined by a range of log KOW (-0.5 – 7.5) and log KOA (-4.5 – 11.5) were used to demonstrate the models applications. In these illustrative applications, the steady-state removal efficiencies of pyrene, arsenic, and the naphthenic acid from the wetland were 41%, 83%, and 31%, respectively. The most efficiently removed chemicals had a log KOW ≈ 6 and log KOA ≤ 2.5. Removal efficiency was lowest for substances showing reduced evapotranspiration flux. This study concluded that wetland treatment could be a feasible method of remediation for certain contaminants in wastewater.