DEMINERALIZATION BY EDS.

Demineralization by electrodialysis can be facilitated and improved by an ion conducting spacer. At very low concentrations the effective thickness of the dialysate compartment with this spacer is equal to or lower than the geometric thickness, i. e. the total voltage drop is lower than the hypothetic ohmic resistance of a layer of dialysate in the absence of polarization. A simple method is suggested for scale control. Tap water is fed to the stack without acidification. The carbonate precipitate adhering to the membranes is dissolved by acid rinse at predetermined intervals. Sulphate precipitation is avoided.