JPS6349523B

PURPOSE:To prevent the deterioration of an ion exchange membrane for a long period of time, by a method wherein an aqueous solution containing an electrolyte is treated with an oxidative substance and the treated solution is adjusted to 0.2ppm or more in the concn. of the reductive substance therein to perform electrodialysis. CONSTITUTION:In supplying an aqueous solution containing an electrolyte to an electrodialytic apparatus in accordance with an ion exchange membrane method, the aqueous solution containing the electrolyte is treated with an oxidative substance and an excessive amount of a reductive substance is added to the treated solution. In this case, the reductive substance in said solution is allowed to remain so as to adjust the concn. thereof to 0.2ppm or more before electrodyalysis is performed. The above mentioned method is adapted to the concn. and desalting of seawater, the desalting of underground water and the desalting and concn. of the other stock solution containing an electrolyte and the prevention of an ion exchange membrane from deterioration and the contamination inhibiting effect of not only said ion exchange membrane but also the interior of a dialytic apparatus are enhanced.