PROCESS FOR PURIFYING CHROMIC ACID WASTE WATER CONTAINING CHROMATE IONS AND RECOVERING A CHROMIC ACID SOLUTION

摘要

1449529 Purifying water containing chromate ions TOKICO Ltd 21 Nov 1974 [21 Nov 1973] 50605/74 Heading C1C A process for purifying waste water which contains chromate ions and simultaneously recovering a chromic acid solution comprising the steps of: (i) continuously passing the waste water through an anion-exchange column system consisting, when all the columns are in service, of two or more serially inter-connected anion-exchange resin columns, to thereby deionize and thus purify the waste water; (ii) subjecting an anion-exchange resin column in the upstream part of said anion-exchange column system to a regeneration treatment when or after the anion-exchange capacity thereof has fallen to such an extent that the influent to the column and the effluent from the column have a substantially equal chromate ion content, the waste water being by-passed around said column during the regeneration treatment; (iii) after completion of the regeneration treatment, returning the regenerated anion-exchange resin column to service in said anion-exchange column system at a downstream part of said anion-exchange column system; (iv) repeating steps (ii) and (iii) on successive upstream anionexchange resin columns when, in turn, their anion-exchange capacity falls to the extent defined in step (ii); and (v) recovering a chromic acid solution which forms the eluate in the regeneration treatment of step (ii).