Woodchip bioreactor (a.k.a., denitrifying bioreactor)
A woodchip bioreactor is a trench filled with woodchips through which subsurface drainage water is routed. In this system, denitrification is the main nitrate removal mechanism through which nitrate is microbiologically converted into mostly nitrogen gas. Denitrification occurs under anaerobic conditions wherein the woodchips constitute the main source of carbon food source for the denitrifying microbial community.