Nitrogen (N) and phosphorus (P) contamination of surface waters from non-point source agricultural pollution are a serious concern nationwide, as well as in the Midwestern US, including Minnesota. Hypoxia in the Gulf of Mexico has been an issue since the mid 1980’s, and is largely attributed to nutrient enrichment of marine waters by N and P entering the Gulf from the Mississippi River. A federal task force recommended a 45% reduction in N and P loads entering the Gulf of Mexico from the Mississippi River in order to reduce the long-term average area of the Gulf hypoxic zone to 5,000 km2 or less (Green et al, 2009).
This innovative proof-of-concept project offers the potential for mitigating significant quantities of nitrogen (N) and phosphorus (P) from entering into agricultural drainage ditches which carry the vast majority of nutrients that enter surface streams and rivers in the Midwestern region. We propose to investigate the potential of a BioElectroChemical Reactor (BECR) to remove N and P from tile drainage water. The system would contain both denitrifying and phosphorus sorbing materials which would be renewable, replaceable and/or recyclable. This approach could also result in reduced hydraulic residence time for treatment of water in the BECR which would mean that more water could be treated in less time than previous methods. This novel approach would remove both N and P, which has not been the case with previously studied bioreactors that were designed to remove only N at the end of subsurface drains, or only P in regions where overland flow occurs. If successful, this project could lead to greater sustainability of agricultural production in Midwestern regions where corn and soybeans are produced.