Capturing Contaminants of Emerging Concern (CECs) with Biofiltration

Project summary:

Biofiltration practices are an urban stormwater treatment practice designed to capture pollutants such as sediment, nutrients, and polycyclic aromatic hydrocarbons (PAHs), among others. The mixed media within biofiltration practices, such as biochar, have the potential to also capture contaminants of emerging concern (CECs), but the effectiveness and best mix design have yet to be determined. This project will measure the effectiveness of media components (e.g., compost, biochar, peat, iron, spent lime, etc.) at common mix ratios to capture CECs using outdoor mesocosm experiments (Question 1). These experiments will optimize the components to balance cost and CEC removal to produce the most cost-effective shovel-ready design.

In addition, existing biofiltration practices will be monitored by the United States Geological Survey personnel to measure CECs in paired inflow (untreated) and outflow (treated by biofiltration media) stormwater samples (Questions 2 and 3). Results from the outdoor mesocosms will be compared to field-monitored CECs (Question 4) to demonstrate how outdoor experiments can be extrapolated to field installation performance. This project expands upon nearly $296,000 invested by the Minnesota Stormwater Research Council and the University of Minnesota Water Resource Center Stormwater Research Program on biofiltration mesocosm experiments and complements approximately $646,000 that has been requested from the Environment and Natural Resources Trust Fund (CEC removal by biofiltration). Through this combined outdoor experiment-scale and field pilot-scale study, guidance will be developed to empower water resource planners and managers with a treatment practice design to remove harmful CECs from stormwater runoff and protect Minnesota's water resources.