Rob Stout | Washington County

Written by Teresa Munn, West Fork Crooked Creek watershed coordinator 

Q. Bioreactors seem to be a relatively new concept in southeast Iowa. What exactly is a bioreactor and how does it work?
A. A bioreactor is a medium of a good carbon source, in my case wood chips, through which tile water is passed and the nitrates are then released as nitrogen gas into the atmosphere.

Q. How did you learn about bioreactors and what made you decide to install one?
A. As a part of the West Fork Crooked Creek watershed, we received a grant from IDALS to improve our watershed by using methods listed in the Iowa Nutrient Reduction Strategy. This was one of the ways to reduce nitrogen in the water that would be a long-term solution so I volunteered a farm to see if there was a location suitable for construction of a bioreactor.

Q. What type of location is best for a bioreactor? What did you take into consideration when choosing your location?
A. The best location is to build it to treat a watershed of 50-75 acres. You need a location beside an existing tile line so that you can divert the water through the bioreactor to remove the nitrates and then allow the clean water to go flow back into the tile system. Then we picked an area that is pattern tiled so that we weren't going to add a lot more tile onto the system. Lastly, we wanted an area that could be easily accessed so that regular monitoring could be done to determine its effectiveness.

Q. Was it difficult to get a design done? Difficult to find a contractor?
A. The district engineer for NRCS designed the project. I asked my contractor that has been building terraces and installing tile for us for the past 30 years to do it and he agreed. He had never built one before but has constructed wetlands projects which use some of the same components. I also have a friend who manages a sawmill who supplied the wood chips, which were of very high quality, which contributes to the success.

Q. Now that you've had the bioreactor for awhile, what do you think of it?
A. I am very pleased with my bioreactor. The results have been far better than was expected. The Iowa Soybean Association has done the monitoring from just after it was constructed through the end of October, and through that time period reduced nitrates in the tile water 97%.