Special Features of Electro-Membrane Recovery of Acids and Alkalis from the Water-Soluble Wastes of Nuclear Power Plants.

The results of studying of the nitric acid and NaOH + KOH alkalis' mixture recovery from concentrated solutions in filter-press-type electrodialyzers with anion-exchange, cation-exchange, and bipolar membranes are presented. The necessity of the technological solutions preliminary purification from calcium and boron compounds was established, in order to obtain crystalline boric acid (H3BO3) and gypsum (CaSO4·2H2O). The possibility of obtaining, from purified concentrated salt solutions, acids and alkalis with a concentration of ~300–600 g/L suitable for reuse is shown. This can be provided only by the electrodialysis with anion- and cation-exchange membranes, while electrodialysis with bipolar membranes is complicated by noticeable contamination of both acidic and alkaline solutions with salts. [ABSTRACT FROM AUTHOR]