METHOD AND APPARATUS TO CONTROL A SALT STREAM TO BE TREATED IN AN ELECTRODIALYTIC WATER SPLITTER

2051664 9011819 PCTABS00002 An aqueous salt feed stream (37') is fed to an electrodialysis water splitter (33) and a dilute salt stream (45) is withdrawn from the water splitter (33). The dilute salt stream (45) is fed to an electrodialysis unit (48) comprising a concentration compartment (C) and a diluting compartment (D), at least part of the dilute salt stream (45') being fed to the concentration compartment (C). An electrodialysis product stream (60) is withdrawn from the concentration compartment (C). The product stream (60) and the raw salt stream (37) are controllably combined to form the aqueous feed stream (37'). In accordance with the method of the present invention the salt concentration of the product stream (60) can be maintained below the salt concentration of the raw salt stream (37). The pH of aqueous salt feed stream (37) can be controlled based on the pH of electrodialysis unit product stream (60).