An oily waste emulsion, in which oil is dispersed in the water phase, may contain any one of several types of oil in a wide range of concentrations. They may be fats, lubricants, cutting fluids, heavy hydrocarbons such as tars, grease, crude oils, and diesel oils, and also light hydrocarbons such as gasoline, kerosene, and jet fuel. Treating the emulsion is usually accomplished using coagulants dosed at an appropriate level to neutralize the electrostatic charge.