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Rosenquist Bioreactor Project

The Rosenquist Bioreactor Project is being facilitated by the MFCRWD through the MN BWSR Drainage Water Quality Program. The goal of this project is to imrpove water quality flowing into Diamond Lake, which is currently impaired due to nutrient loading. 

This site already has an established bioreactor that was installed about ten years ago on the west corner of the Rosenquist's field. The new project will build upon that success by installing another woodchip bioreactor where tile lines converge before discharging into Diamond Lake. 

Woodchip bioreactors are used as an edge-of-field conservation practice designed to reduce nutrient losses, specifically nitrate-nitrogen) from agricutlural drainage water. When tile-drained water leaves a field, it is routed through a trench filled with woodchips, typically locted within a grassed buffer strip. 

Aerial image with labeled areas: "future Bio reactor site," "wants the tree gone," houses, roads, and "Diamond Lake."
Location of future bioreactor site on the Rosenquist field.
Diagram of woodchip bioreactor. Demonstrates how water flows into the bioreactor, a water control structure is used to divert tile flow into the bioreactor, goes through the woodchips for filtration, and the nitrogen gas and water exits the bioreactor.
Diagram of woodchip bioreactor. Demonstrates how water flows into the bioreactor, a water control structure is used to divert tile flow into the bioreactor, goes through the woodchips for filtration, and the nitrogen gas and water exits the bioreactor.
Aerial image with labeled areas: "future Bio reactor site," "wants the tree gone," houses, roads, and "Diamond Lake."
Diagram of woodchip bioreactor. Demonstrates how water flows into the bioreactor, a water control structure is used to divert tile flow into the bioreactor, goes through the woodchips for filtration, and the nitrogen gas and water exits the bioreactor.

 

Inside the bioreactor, microbes use the carbon from the woodchips as food and, in the process, convert nitrate from the water into nitrogen gas, which safely returns to the atmosphere. This process, known as denitrification, naturally removes excess nitrogen from drainage water before it reaches nearby water bodies. 

According to the Minnesota Department of Agriculture (MDA), "a woodchip bioreactor system utilizes woodchips as a carbon source and the ability of certain bacteria to use nitrates for respiration under low oxygen conditions"(MDA), Field Evaluation of Controlled Drainage and Woodchip Bioreactors in Reducing Contaminant Losses, 2019). 

How will this impact water quality quality? Will it help Diamond Lake? Diamond Lake has been experiencing nuttient loading and algal blooms due to excess nitrogen and phosphorus enetering from the surrounding landscape. This bioreactor will help by:

  • Filtering and cleaning tile drainage water before it enters Diamond Lake
  • Reducing nitrogen runoff and improving nutrient management 
  • Improving local water quality
  • Supporting ongoing restoration efforts
  • Reducing outflow of nutrient-rich water, contributing to healtheir aquatic ecosystems

 

Learn more about woodchip bioreactors, how they work, and their water quality benefits through the following resources:

MN NRCS's Contructing a Dentrifying Woodchip Bioreactor

 

Improving Water Quality in Agricultural Drainage with a Wood Chip Bioreactor (Prinsco Inc)

 References:

  • Minnesota Department of Agriculture (MDA). Field Evaluation of Controlled Drainage and Woodchip Bioreactors in Reducing Contaminant Losses from Farmed Fields with Natural Background Estimate.
  • U.S. Department of Agriculture – Natural Resources Conservation Service (USDA NRCS). Conservation Practice Standard: Denitrifying Bioreactor (Code 605).
  • Iowa State University Extension and Outreach. Woodchip Bioreactors for Nitrate in Agricultural Drainage.