Floating covers are made to cover fluids such as water, vinasse and/or effluent treatment. By covering the fluids, the shelters of external elements that may dilute or let it evaporate. Floating covers are also used for biodigesters and create an anaerobic environment (oxygen-free) and to capture methane gas from the anaerobic bacterial process. Floating covers are made of different types as geomembranes HDPE, LLDPE, EPDM, XR5, and others. They generally have a system of checks, floats and pumps to drain rainwater to keep floating directly on the effluent.