McHenry County Bioreactor

Background

Since 2015, IFB has contributed to an impressive statewide effort, the NLRS. Through leadership and participation from our farmer members across the state, IFB has been able to make meaningful contributions toward water quality improvements in Illinois. From 2016 to present, IFB has committed approximately $1.5 million of its own funding to build and maintain its sustainability programs. The NLRS is a science-based framework for using research, technology and industry experience to assess and reduce nutrient loss to Illinois waters and to the Gulf of Mexico. The NLRS sets forth a plan to leverage existing programs to optimize nutrient loss reduction while promoting collaboration, research, and innovation among the private sector, academia, non-profits, wastewater treatment agencies, the agricultural sector, and state and local government. The primary goals include reducing nitratenitrogen losses by 15% and reducing total phosphorus losses by 25% by the year 2025 from established baseline conditions. The NLRS was released in July of 2015 after multiple years of stakeholder discussions in which IFB actively participated. Since 2015, IFB has continued its participation in NLRS meetings and work groups in order to strategically guide the effort. In addition, IFB created new programs in 2015 to support farmer implementation of best management practices (BMPs) to help Illinois meet the goals of the NLRS. For the past several years, IFB has made it an organizational priority to lead on environmental issues, most notably, the NLRS. IFB’s NLRS efforts focus in four priority areas: 1) education and outreach to farmers, landowners and the general public; 2) supporting research of best management practices to reduce nutrient loss from agricultural fields; 3) supporting farmer implementation efforts across the state; and 4) demonstrating progress toward the long-term goals of the NLRS. The IFB Board of Directors committed significant financial resources and support from staff to accomplish some ambitious goals, allowing IFB to tackle environmental challenges head-on. IFB will continue to prove that voluntary, incentive-based conservation, based on science, will move the needle on water quality improvements in our state. The IFB Nutrient Stewardship Grant Program is one example of the many ways IFB is creating lasting impacts in implementing the NLRS across Illinois. This program funds CFB projects throughout the state focused on improving soil health and water quality. Since 2015, IFB has dedicated over $550,000 to CFBs to complete a wide range of unique projects, including planting test plots of cover crops, watershed planning, water testing, hosting education and outreach activities.

 

 

 

In 2020, the McHenry County Conservation District and the McHenry County Farm Bureau partnered up for the woodchip bioreactor field day at the site where the bioreactor was installed. Since Spring of 2021, MCCD volunteers have begun taking water samples at the inlet and outlet structures of the bioreactor, which were then delivered to research partners at the University of Illinois with the help of the McHenry County Farm Bureau. The pictures above show these partners gathering for a Nutrient Stewardship Field Day at the site of the bioreactor. The bioreactor project, initiated by the Illinois Farm Bureau, serves the purpose of standardizing the implementation of water-quality practices and prioritizing envirnomental sustainability. The woodchip bioreactor has proven to be successful in reducing nutrient loss, which is something that every farmer strives for. The Illinois Farm Bureau has already invested over $1.5 million toward nutrient loss reduction in Illinois. Below are videos surrounding both the 2020 Woodchip Bioreactor Field Day and the 2021 Woodchip Bioreactor Field Day.

 

2020 shortened version (click on image to open link):

 

2020 full length version (click on image to open link):

 

2021 shortened version (click on image to open link):

 

2021 full length version (click on image to open link):

 

 

The Science Behind It

 

Nitrogen is an element that is essential for life on this planet but excess amounts of nitrogen in water cause concern for human and environmental health. When excess amounts of nitrogen are found in water, such as tile drainage, a woodchip bioreactor is one option to clean the water before the nitrogen causes a problem downstream.

A woodchip bioreactor is a trench full of woodchips that cleans nitrogen from water by maximizing the process of denitrification. Denitrification is a natural part of the nitrogen cycle where native bacteria convert nitrate (a form of nitrogen) in the water to harmless nitrogen gas. It’s these bacteria that lend the “bio” to the name bioreactor. The woodchips serve as the bacteria’s food source, and as nitrate in the water flows by the bacteria, they convert the nitrate to nitrogen gas, thus cleaning the water.

 

WOODCHIP BIOREACTOR DESIGN

With the assistance of an Illinois Farm Bureau (IFB) Nutrient Stewardship Grant and in partnership with McHenry County Farm Bureau (CFB), a 40 ft wide x 40 ft long bioreactor on a McHenry County Conservation District (MCCD) property was built in 2020 to clean nitrate in water from a 45-acre tile drained field. The drainage system outlet pipe was 12” in diameter, which was relatively large compared to the 6” or 8” outlet pipe size for which most conventional bioreactors are designed. Most of these conventional bioreactors are long and narrow trenches, for example, 10 ft wide x 50 ft long. However, because this outlet tile pipe was a larger diameter and would thus carry more water than most bioreactor situations, this bioreactor was purposely designed to be wider. Water that is not captured by the bioreactor bypasses to the stream and is untreated.

 

NITROGEN TREATMENT RESULTS IN YEAR 1

In summary, from April 2021 to April 2022, the bioreactor captured 78% of the flow and removed 170 pounds of nitrate-nitrogen. This means the bioreactor removed 11% of the nitrogen that would have otherwise gone downstream.

 

 

Devoted volunteers have collected samples of water entering and exiting the bioreactor at least weekly since April 2021. Every sample event shows that nitrate is being removed across the bioreactor. In other words, the nitrate concentrations in the water leaving the bioreactor (blue triangles in the figure) are all lower than the nitrate concentrations in the water entering the bioreactor (red circles) for samples collected on the same date.

The nitrate concentration reduction provided by the bioreactor (the difference between the circles and triangles) is impacted by how fast the water moves through the woodchips. When the bioreactor’s flow rate was less than 15 gallons per minute, like in late summer 2021, the bioreactor generally removed all the nitrate that entered. However, when drainage flows increased starting in October 2021, the difference between the nitrate concentrations for water entering and exiting the bioreactor was reduced. This is because the water was moving faster through the bioreactor, which gives less time for the natural bacteria to do their biological process of denitrification.

An additional compounding factor is that winter and spring drainage water flows are cooler than summer flow. Water temperature impacts all biological processes, including denitrification, with cooler temperatures slowing these processes.