Method for treating saline wastewater and device for treating same

The purpose of the present invention is to provide a saline wastewater treatment method which is low in cost as a matter of course and with which sodium chloride can be highly efficiently converted into an effectively utilizable substance in high yield with reduced environmental burdens. This saline wastewater treatment method is characterized by satisfying all of T2sodium hydroxide yielded on the negative electrode inserted into the negative-electrode chamber of an electrolytic tank is brought into contact with carbon dioxide to yield sodium carbonate and/or sodium hydrogen carbonate, T2 (°C) is the temperature of a precipitation tank in which the sodium carbonate and/or sodium hydrogen carbonate yielded in the aeration tank is crystallized and the crystals of sodium carbonate and/or sodium hydrogen carbonate are separated from an aqueous solution by solid-liquid separation and recovered, and T3 (°C) is the temperature of a heat exchanger in which the aqueous solution of sodium carbonate and/or sodium hydrogen carbonate separated in the precipitation tank is heated before being supplied to the negative-electrode chamber of the electrolytic tank.