Project overview
The primary objective of this project is to characterize the effectiveness of stormwater best management practices (BMPs) that incorporate biochar-augmented filtration media for comprehensive contaminant removal from stormwater at the catchment scale. While biochar- augmented filtration systems are an emerging technology for improved removal of bacteria and dissolved contaminants from stormwater, little is known regarding (i) the type(s) of biochars that are most effective for comprehensive contaminant removal, and (ii) how biochar maintains its contaminant removal capacity upon field deployment.
We therefore propose to (1) conduct laboratory tests to evaluate the effectiveness of Minnesota-produced biochars for removal of a suite of contaminants from stormwater, and (2) evaluate the most promising biochar for its performance in field-scale filter media testbeds. We will install biochar-augmented filter media into an existing testbed located at the Mississippi Watershed Management Organization (MWMO) office building. This system treats the building’s roof and parking lot runoff using three filter cells in parallel, enabling comparison across three different media configurations. We propose to evaluate a broad suite of stormwater contaminants, including bacteria (i.e., E. Coli), chloride, nutrients (e.g., total nitrogen and phosphorus), heavy metals (e.g. zinc and copper), organic contaminants (e.g., pesticides).
The intended outputs of this project will be (1) a peer-reviewed publication that advances knowledge regarding the comprehensive contaminant removal performance of biochar-augmented filter media following field deployment, and (2) a written report that provides practitioners with best practice recommendations with respect to the design of BMPs that incorporate biochar-augmented filter media.
Research findings
- Retention of total suspended suspended solids improved gradually over the first 2 years
- Compared to the sand filter, the biochar filter retained more nitrate/nitrite and zinc, even though it received a greater treatment volume
- The biochar filter did not show increased retention of total organic carbon (TOC) or E. coli. These results moderately contrast previous studies’ results, but the difference may be due to the different temperatures that the biochar is produced at.
What does this mean for Minnesota?
This project aimed to assess the effectiveness of biochar in removing pollutants from stormwater, and its results show that biochar is a viable option to put in filters. With a new material to work with, practitioners will be better able to amend filters and infrastructure to keep our stormwater cleaner.
Project assets
Reports and Presentations
- Final report 2023.pdf
- Project update 2021 .pdf
Publications and student work
- Evaluating the simultaneous retention of organic matter, organic contaminants, and Escherichia coli (E. coli) in biochar-amended biofilters, Environmental Science Water Research & Technology, 2025.