Abstract: Apparatus and method are provided for concurrently decreasing the cyanide and heavy metal content of an aqueous solution, such as a waste water.The apparatus comprises an electrochemical cell provided with separate cathode and anode compartments. Each of the compartments contains a bed of electrically conductive particles. The compartments are separated by an electronically nonconductive foraminous member.In accordance with the method, an aqueous solution containing cyanide ion and at least one heavy metal in soluble form is passed sequentially through the beds of electrically conductive particles contained in each of two compartments of an electrochemical cell. A direct electric current is passed between the two compartments making one compartment cathodic and the other anodic. The heavy metal is deposited upon the particles in the cathodic compartment and the cyanide is oxidized in the anodic compartment.

Abstract: A method for chemically removing phosphates from waste waters by treating the phosphate-containing waste water with a trivalent rare earth salt, generally as a mixture of such salts, to form an insoluble rare earth phosphate precipitate, and then separating the precipitate from the waste water. The rare earth precipitant salt, such as lanthanum chloride or sulfate, may be regenerated by treating the rare earth phosphate precipitate with a strong or weak alkali as regenerant, preferably aqueous sodium hydroxide or sodium carbonate, to form a soluble alkali metal phosphate. The aqueous alkali regenerant may be recovered by treatment of the formed sodium phosphate with lime to precipitate the phosphate as a calcium phosphate complex salt.Where it is desired to precipitate phosphate but avoid regeneration of the rare earth precipitant salt, a combination treatment using aluminum-lanthanum or iron-lanthanum as precipitant salt is preferred.

Abstract: Apparatus and method are provided for concurrently decreasing the cyanide and heavy metal content of an aqueous solution, such as a waste water.The apparatus comprises an electrochemical cell provided with separate cathode and anode compartments. Each of the compartments contains a bed of electrically conductive particles. The compartments are separated by an electronically nonconductive foraminous member.In accordance with the method, an aqueous solution containing cyanide ion and at least one heavy metal in soluble form is passed sequentially through the beds of electrically conductive particles contained in each of two compartments of an electrochemical cell. A direct electric current is passed between the two compartments making one compartment cathodic and the other anodic. The heavy metal is deposited upon the particles in the cathodic compartment and the cyanide is oxidized in the anodic compartment.