Abstract: Oil is separated from an aqueous mixture by first feeding the oil-water mixture into a separation tank and allowing the mixture to separate by gravity so that the oil rises to the surface, forming a layer above the aqueous phase; then removing the layer of oil from the surface. The lower aqueous phase, typically containing residual oil in emulsified form, is removed through an outlet near the bottom of the tank and transferred to a second tank, forming a pool therein. The water is removed from the second tank by the action of an air-operated pump through a float-controlled ball valve to an external filter for removal of residual oil.