A method and apparatus for separating mixtures of fluids having different densities. According to one aspect of the invention, a lower density fluid is separated from a higher density fluid. A mixture of the two fluids is received in a tank. A centrifugation of the mixture is induced in the tank. The lower density fluid is evacuated from the tank until the level of an interface created at least in part by the centrifugation between the higher density fluid and the lower density fluid reaches a predetermined threshold.