METHOD OF REGENERATING EXHAUSTED SOLUTIONS CONTAINING SULFURIC ACID Russian patent published in 2000 - IPC

FIELD: waste water treatment. SUBSTANCE: invention, in particular, concerns exhausted solutions formed in electroplating shops, at metallurgical and chemical enterprises, etc., containing sulfuric acid, iron and other metal ions. Exhausted concentrated solutions are preliminarily combined with wash waters and mixtures are passed through cathode space of the first electrolyzer of an electrolyzer series and fed into oxidation reactor to oxidize ferrous ions to ferric ions. Ferric hydroxide is separated on filter. Filtrate consecutively passes through cathode spaces of subsequent series electrolyzers and, after each step, intermediate metal hydroxides are separated. After separation of metal hydroxides in the last step, solution is passed through anode spaces of the series electrolyzers in the inverse direction. Solution coming out of the first electrolyzer is subjected to low-temperature evaporation, after which concentrate of purified acid is recycled and condensed water vapor is used in washing operations. EFFECT: reduced consumption of sulfuric acid, developed wasteless process, and enabled recovery of metals in reusable form. 1 dwg