A cavitation device is used to heat and facilitation the separation of mixtures and emulsions of oil and water. Waste heat from the power source for the cavitation device may be utilized to elevate the temperature of incoming mixtures or emulsions. The heated mixture of emulsion is sent to a separation vessel where vapor may be removed and/or recovered, and where oil is removed as it separates into an identifiable layer. The separation vessel may be a flash tank.