Grit removing, deoiling and degreasing is a treatment carried out after the fine screening process. The objective is to send the effluents into tanks / basins allowing the reduction of flow velocities thus making deposit / decant the sands and float the grease. In the case of combined units, the injection of micro-air bubbles allows acceleration of the flotation of fat. In the majority of cases, the sands are extracted and conveyed by an Archimedes’ screw and the greases are scraped at the surface.