Process for the recovery of chromic acid solution from waste water containing chromate ions

Abstract

A chromic acid solution can advantageously be recovered from the waste water by a process which comprises passing the waste water successively through an anion-exchange column system consisting of two or more serially interconnected anion-exchange resin columns each packed with an anion-exchange resin thereby deionizing the waste water, and, in the course of this deionization treatment, column backwashing the first anion-exchange resin when the anion-exchange capacity thereof has fallen to the point where the influent to and the effluent from the first anion-exchange resin column have become substantially equal in terms of chromate ion content. In the course of the regeneration treatment, the waste water is diverted to enter the anion-exchange column system through the second anion-exchange resin column. After the regeneration treatment has been completed, the first anion-exchange resin column is put back into service in the anion-exchange system so as to serve as the last stage. Thereafter the procedure described above is repeated with respect to the successive anion-exchange resin columns composing the system thereby permitting passage of the waste water to be carried out continuously. The eluate which results from the regeneration treatment is recovered as a reusable chromate solution.

Dependencies are inferred from the claim text.