Capturing contaminants of emerging concern with biofiltration

Project overview

This project is is a continuation of two previous studies of biofiltration media mixes. You can read about those projects by following these two links:

Contaminants of Emerging Concern (CECs) are newly recognized stormwater pollutants that are not yet regulated. These include pesticides, herbicides, and pharmaceuticals. When these compounds enter our waterbodies, they harm fish, mussels, insect larvae, and humans. Therefore, stormwater managers need cost-effective designs for stormwater treatment features that are capable of removing CECs from stormwater.

Cities, counties, and watershed districts rely on stormwater ponds and biofiltration basins to remove sediment and nutrients from runoff. Biofiltration features have not been designed to remove CECs, but they have the potential to do so. The goal of this research project is to develop new biofiltration designs that can remove CECs from stormwater runoff.

To do that, the research team will conduct outdoor experiments that will determine the best materials (compost, biochar, peat, iron, spent lime) and mix ratios for capturing CECs. Using this knowledge, the team will optimize the mises to produce the most cost-effective design.  

Research questions

  • Which biofiltration media mix ratios of compost, biochar, peat, and iron-sand are optimal for removing CECs from stormwater runoff?
  • Which CECs are present in urban runoff to biofiltration practices, and at what concentrations?
  • Which CECs are captured by one or more existing field-installed biofiltration practices, and at what efficiency?
  • Does CEC performance in mesocosm experiments correlate with field-measured capture in existing biofiltration practices?

Key innovation/contributions

This project will identify filter media mixes can remove CECs from runoff.

What does this mean for Minnesota?

This will help us understand how to design biofiltration practices that can capture CECs before they are carried into our waterbodies, which will help stormwater managers to cost-effectively meet their stormwater treatment goals. Ultimately, this will help to preserve and improve water resources and habitats throughout Minnesota.

Additional research is underway that will expand our understanding of how to support plant growth on biofiltration media mixes.

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Reports and Presentations