The grease separators are used for the pretreatment of waste water, civil (coming from the kitchens, washing machines, sinks, showers, etc). before they are discharged into the public sewage system or to mount an adequate treatment plant (activated sludge, sub-irrigation, filtration system percolating, etc).

The fat is separated by a physical process of removing all of the substances whose specific gravity is less than that of the wastewater, which is the type of substances that are typically found in wastewater from kitchens, restaurants or canteens.

The fat should be removed because it can have serious harmful consequences in the course of the next treatment, for example, during the biological process, aerobic, anaerobic digestion, decanting or lifting.