Electrodialysis desalination process system for seawater

An electrodialysis desalination method for seawater comprising:

• providing an electrodialyzer having a plurality of serially connected electrodialysis cells each comprising a plurality of alternating arranged cation exchange membranes and anion exchange membranes connected to one another between two electrodes to form a plurality of dilution compartments and concentration compartments therebetween;
• supplying seawater to the first electrodialysis cell for separating the seawater into two portions including a diluted solution from said dilution compartments and a concentrated brine solution from said concentration compartments, respectively, by electrodialyzing;
• extracting dilute solution from the dilution compartments of at least one of said electrodialysis cells;
• heating only the extracted dilute solution to within the temperature range of 30.degree.-90.degree. C. to maintain the dilute solution at a temperature higher than that of the concentrated brine solution in succeeding electrodialysis cells;
• returning all the heated extracted dilute solution to the corresponding dilution compartments of the next cell in said plurality of electrodialysis cells;
• and
• thereafter passing the heated dilute solution and concentrated brine serially through the remaining ones of said cells, said concentrated brine being supplied only to said concentration compartments and said dilute solution being supplied only to said dilution compartments in the remaining ones of said serially connected electrodialysis cells.