Abstract: Disclosed is an improved process for purifying waste water in which a waste water containing contaminants, including dispersed solids, water-immiscible organic materials, and metallic cations, is first introduced to a sedimentation zone to remove water-insoluble materials having a density higher than that of water, then to a flotation zone to separate as an upper layer water-insoluble and water-immiscible materials having densities lower than that of water. The waste water stream is then introduced to an adsorption zone, where activated carbon particles are added to adsorb remaining water-insoluble and water-immiscible materials, following which the solids are removed in a liquid-solids separation zone. The aqueous phase from the last zone is then passed through a cation exchange zone to remove cations.