University of Illinois Extension
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Bioreactors, Water Table Management, and Water Quality

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.

Bioreactors aid in denitrification of nitrates

Image Courtesy U.S. Geological Survey

Image Courtesy Farm Journal Magazine

Image Courtesy Farm Journal Magazine

How Bioreactors Work


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.

first generation bioreactors


second generation bioreactors

In the second generation, a control structure was installed on one end with a diversion structure on the other.

second generation bioreactors

second generation bioreactors


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.

third generation bioreactors

third generation bioreactors


Embarras River Watershed

The following pictures show a research bioreactor installation draining 50 acres in the Embarras River Watershed in Illinois in 2012.

  • Embarras River Watershed
  • Embarras River Watershed
  • Embarras River Watershed
  • Embarras River Watershed
  • Embarras River Watershed
  • Embarras River Watershed
  • Embarras River Watershed
  • Embarras River Watershed
  • Embarras River Watershed
  • Embarras River Watershed