Flotation DAF is a process using air dissolved in water in order to achieve solid/liquid separation.
In order to increase the process efficiency, chemical additives are normally dosed. Coagulation followed by flocculation inside the treated fluid is achieved. Coagulation is meant to destabilize solid particles in stable equilibrium inside the fluid, while flocculation is meant to gather the particles into bigger and more extended flocks.
Flotation, consisting of saturation of a certain quantity of water (about 5 BAR which reduces the pressure in the system), takes place when flocks collide with water saturated with air, creating an aggregate made of flock - microbubble of air rising up to the liquid surface by means of the density difference of the aggregate face to the surrounding liquid.