Study on Recycling Byproduct Salt using Bipolar Membrane Electrodialysis Equipment

Abstract

The number of leachate treatment facilities with desalination treatment is increasing. When desalination is performed, concentrated solution and dried salt (byproduct salt), which is obtained by evaporating and solidifying the concentrated solution, are produced together with the desalinated water. In recent years, some byproduct salt has been recycled as antifreeze agents, and some has been used as disinfectants at terminal treatment plants by generating NaClO through electrolysis. However, there are many areas that do not use antifreeze agents and nearby areas that do not use disinfectants. Using bipolar electrodialysis (BPED) as one of the recycling methods, a development study was conducted assuming that acids and alkalis are generated and used as a neutralizing agent. Currently, BPED is used in the food and medical fields as a method for producing organic acids and alkalis from organic salts and acids and alkalis from inorganic salts. In this study, we conducted a basic study with different generation sources (leachates from general waste and industrial waste) and different discharge types (concentrated solution and dried salt) of byproduct salt. As a result, HCl with a concentration of 2.82mol/L to 4.23mol/L and NaOH with a concentration of 1.43mol/L to 3.04mol/L were produced.