How Bioreactors Work
Bioreactors consist of a of buried trench with woodchips through which the tile water flows before entering a surface water body. Microorganisms from the soil colonize the woodchips. These microorganisms "eat" the carbon from the woodchips and "breathe" the nitrate from the water. Just as humans breathe in oxygen and breathe out carbon dioxide, these microorganisms breathe in nitrate and breathe out nitrogen gas, which exits the biofilter into the atmosphere. Through this mechanism, called the denitrification pathway, nitrate is removed from the tile water before it can enter surface waters. Dr. Richard Cooke, University of Illinois.
first generation bioreactors
The first generation bioreactors simply had tile on both ends and woodchips filling the hole. Most of the water bypassed the bioreactor.
second generation bioreactors
In the second generation, a control structure was installed on one end with a diversion structure on the other.
third generation bioreactors
In third generation systems, the diversion and capacity control structures have been combined into one, resulting in lower installation costs and easier installation.
Embarras River Watershed
The following pictures show a research bioreactor installation draining 50 acres in the Embarras River Watershed in Illinois in 2012.