"US: "Bioreactors" capture nitrates from drainage water"

South Dakota State University Extension is leading a project that will have five demonstration "bioreactors" installed by the end of 2013. The conservation drainage systems are designed to reduce nitrates that may be in drainage waters. A bioreactor includes a subsurface trench located along the edge of a field and filled with a carbon source, typically wood chips, through which the drainage water is passed. The carbon source in the trench serves as a material for soil microbes to colonize. The microbes feed on the carbon source and "breathe" the nitrate, converting it into nitrogen gas. This denitrification releases nitrogen gas harmlessly into the atmosphere. The demonstration project was funded by a Conservation Innovation Grant. The sites will be monitored for their performance in removing nitrates and the information will be utilized in helping establish best management practices and potential cost share guidelines for installation of future sites through NRCS conservation programs.

For more info:

http://igrow.org/news/protecting-water-quality-is-the-goal/