A constructed wetland with woodchips can clean drainage water for nitrogen (and phosphorus). The drainage water is passed through 1-several basins with woodchips, which form a form of natural treatment plant, where microorganisms reduce the nitrogen concentration in the drainage water before it is passed on to the aquatic environment. The exact size of the mining area is adjusted according to how large the catchment area is, a constructed wetland at 0,2-03 hectare will be able to clean drainage water from about 100 hectares.
Example of project working with constructed wetland with woodchips: SupremeTech
Videos: The MMM-project (Minivådområde Med Matrice = constructed wetland with matrice (woodchips)
Farms with drone videos