Flotation is a physical type process, used for the separation of solid or liquid particles from a liquid phase. The main goal is to remove non-emulsified oils and greases and, in general, all those substances, having a low specific weight, hard to be settled, which are present in the liquid to be treated. In fact, the separation is carried out by bubbling within the liquid phase minute air bubbles, which adhere to the particulate material with a dragging effect. If the buoyancy force of the resulting particle is high enough, this will tend to rise toward the surface of the liquid. n particular, the process includes a first phase, during which a part of the treated water, exiting from the flotation tank, is pumped, mixed and pressurized with air at 6 bar, in order to bring into solution the greatest possible amount of air. Subsequently this mixture is suddenly depressurized and fed back into the flotation tank, mixing it to water input to be treated. The particles, that in consequence of flotation are collect on the surface of the liquid, are continuously removed by a scraper blade and conveyed into a storage tank.

The main advantage of a flotation treatment, compared to sedimentation one, is the ability to remove more completely and in shorter time slight particles of minute dimensions, characterized by extremely low sedimentation speed.