Abstract: An apparatus and a method for separating a light liquid from a heavy liquid in a mixture of these liquids are provided which enhance the gravitational separation of such liquids. Thus, water laden with greases such as from a commercial kitchen is contemplated to be substantially rid of the greases by the present apparatus and method. The apparatus comprises a separation chamber; an inlet port; an exit port for each of the light and heavy liquids, with the exit for the light liquid being positioned at about the fluid level of the mixture of liquids; a level control for maintaining the fluid level; and a heater element to heat the mixture, thereby decreasing the viscosity of the light liquid and further driving its separation from the heavier components of the mixture. In the preferred practice of the invention, a skimmer and a series of fluid flow obstacles are also employed along with the heater element to achieve optimal separation.