CONSTRUCTED WETLANDS WITH FREE WATER SURFACE FLOW (FWS)

FWS systems consist in basins or channels where the water surface is exposed to the atmosphere and the soil, constantly submerged, constitutes the support for the roots of the emerged plants; in these systems too the water flow is horizontal and the height of basins is generally limited to a few tens of centimetres.

In these systems removal mechanisms reproduce exactly all characteristics of natural autodepurative capacity of wetlands.