Attendees of the Iowa Learning Farms webinar on Wednesday joined Dr. Laura Christianson, assistant professor, Department of Crop Sciences, University of Illinois, for a “stay-cation” tour of bioreactors around the world. Denitrifying woodchip bioreactors are promoted in the U.S. Midwest to clean nitrate from tile drainage, but they are also being tested around the world for a variety of applications.
Denitrifying woodchip bioreactors are a practical and flexible technology. They involve routing tile water through a bed of woodchips and often do not require land to be taken out of production. Bacteria use the woodchips as a carbon source and, through the process of denitrification, convert the nitrate in the water into nitrogen gas. The use of bioreactors is driven by the local context, needs, and goals, and the practice can be adapted as needed.
Stops on the tour included Denmark, Germany, Spain, Iran, and Madagascar. In Denmark, the local goal is to remove nitrogen and phosphorus from agricultural drainage water and the bioreactors are paired with wetlands to address excess nitrogen and phosphorus. A stop in Germany showed how bioreactors can be used in drainage ditches to remove nitrogen, an idea that has also been trialed in Illinois and Belgium.
In Spain, desalination of groundwater for irrigation led to the concentration of nitrate in the brine and on-farm desalination systems were banned after a eutrophication event in the nearby saltwater lagoon. Woodchip bioreactors have been proposed as a course of action to denitrify the nitrate-rich brine from the desalination process. In Iran, bioreactors are being used to treat nitrogen in their irrigation and drainage effluent. In Madagascar, bioreactors are being used to treat human fecal sludge using locally sourced filter materials.
To learn more about how bioreactors are being used around the world, watch the full webinar!
Join us next week, on Wednesday, January 27 at noon, for the webinar “The Iowa State Rural Drinking Water Survey: Some Preliminary Results and Insights” presented by Gabriel Lade, assistant professor of economics, Macalester College.