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.

Abstract: Improvement in the reduction of Mg, Ca, Na, K and Al in crude phosphoric acid using an ion exchange resin bed, comprising preclarifying the feed acid with flocculant polymer and placing a filter aid precoat on the resin bed. As part of the preclarification process, a compatible soluble sodium compound, such as sodium carbonate, is added to the feed acid to speed the flocculation process.