Bioreactors on the Shore
Protecting Maryland’s Eastern Shore Ecosystems with Nature-Based Scientific Solutions
Wood Chip Bioreactor Flyer
Step 1: Phosphorus Sorbing Filter
We constructed the first Phosphorus Sorbing Filter in the country using a newly patented process developed by Chad Penn at Oklahoma State University. Our project area is located behind a large farm pond. This pond receives drainage from 320 acres of crop land and from the production area of the dairy via shallow groundwater and surface flows. We pull oxygenated water from the surface of the pond using a Faircloth Skimmer that floats on the surface. This enables us to maintain a constant, controlled flow through our projects and increase the storage capacity of the pond during storm events.
Step 2: Wood Chip Bioreactor
Once water passes through the 68 tons of treated slag (a by-product of steel production), the water is fed to a wood chip bioreactor. The bioreactor is a trench, 100 feet long and 30 feet wide, lined with a pond liner and filled with 1-2 inch wood chips covered with about a foot of dirt. This creates an anaerobic environment that facilitates the conversion of nitrate, a water soluble and biologically available form of nitrogen, into nitrogen gas. Nitrogen gas is stable and harmless. In fact it makes up 70% of the air we breathe.
Natural Solutions
The entire project is a gravity fed system. There are no mechanical parts. Monitoring conducted by the Midshore Riverkeeper Conservancy shows a greater than 90% removal of nitrate in these bioreactors in Maryland when eight hours of retention time can be achieved. The Phosphorus Filter medium will work for approximately two years at full efficiency. Ongoing monitoring will address questions of the rate of continued nitrate removal. We are hopeful that we can find funding to replace the slag to increase the life span of the project at that time.
We worked closely with Maryland Department of Agriculture, Kent County Soil Conservation District and USDA Natural Resources Conservation Service in the design and installation of these projects.