New Approaches to Comprehensive Electrochemical Processing of Sulfate-Chloride High-Mineralized Wastewater Treatment Residues

Abstract

The results of electrochemical processing of spent acidic, neutral, and alkaline sulfate-chloride-containing regenerative solutions in two- and three-chamber electrolyzers are presented. It has been determined that the highest current efficiency for the products of electrodialysis can be achieved in the presence of hardness ions when processing acidic sulfate-containing solutions using three-chamber electrolyzers. It has been established that during electrodialysis of alkaline solutions after regeneration of anionites containing chloride ions, accumulation of alkali occurs in the cathodic region, and in the anodic region, chloride ions accumulate due to diffusion through the anion exchange membrane during the first stage, followed by preferential oxidation of chloride ions with liberation of free chlorine during the second stage. It has been shown that electrodialysis can effectively solve the problem of comprehensive processing of neutral, alkaline, and acidic regenerative sulfate-chloride-containing solutions, with the production of alkali and acid at concentrations suitable for reuse in regeneration processes.

Keywords

• electrochemical processing
• electrodialysis
• spent regenerant solutions
• sulfate-chloride solutions
• three-chamber electrolyzers
• anion membrane
• cation membrane