An Electrowetland is a natural wastewater treatment system that generateselectricity from the oxidation of the organic matter. It is based on aconventional Horizontal Subsurface Flow Constructed Wetland (HSSF CW) inwhich electrodes are introduced. Therefore, it consists on a planted and permanently flooded gravel basin in which wastewater flows horizontally fromone side to the other of the system crossing the electrode layer.

Electrodes implementation and the electrical connection stablished through themstimulate the development of an exoelectrogenic biofilm able to transfer theelectrons resulting from the degradation of the organic matter to an externalcircuit thus generating electricity. Wastewater treatment efficiency is alsoimproved resulting in lower wetland surface requirements when compared toconventional wetlands.

To date, very few Electrowetland pilot-scaleexperiences have been reported and therefore, the design specificationsstablished in this document constitute a proposal based on the conclusionsobtained in the lab-scale experiments already published.