Identifying Nitrogen Removal Limitations in Constructed Wetlands Treating Agricultural Tile Drainage

  • Denitrification-mediated nitrogen (N) removal has occurred at a limited rate in constructed wetland 1 (CW1) located in Bureau County, Illinois.
  • Sediment organic matter (OM) concentrations increased greatly within CW1 from nearest the inlet and decreasing to the wetland outlet during 2016 and 2017, while nitrate decreased from the inlet to the outlet at the same locations.
  • The outlet half of the wetland consistently had higher concentrations and more labile OM with a higher abundancy of known denitrifying bacteria that resulted in higher removal efficiency as captured tile drainage moved through the wetland towards the outlet.