SEAWATER TREATMENT METHOD

摘要

In a seawater treatment method which comprises subjecting seawater to coagulation with a coagulant and solid-liquid separation and then conducting RO treatment of the resulting seawater, the present invention makes it possible to provide high-quality feed water for the RO treatment, even when the amount of the coagulant added is reduced. The use of this high-quality feed water enables the RO treatment to be stably conducted over a long period. This seawater treatment method is a method for pre-treating seawater prior to membrane separation, said method being characterized by adding a cationic organic flocculant and/or an inorganic coagulant to seawater to conduct reaction, thereafter adding an alkaline solution of a high-molecular compound which has a phenolic hydroxyl group and which is insolubilized under a high salt concentration to the resulting seawater to conduct agglomeration, and then subjecting the thus treated seawater to solid-liquid separation. The treated seawater obtained by the method is thereafter desalinated by membrane separation.