METHOD FOR PRODUCING SODIUM HYPOCHLORITE, AND SODIUM HYPOCHLORITE PRODUCTION DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a method for producing sodium hypochlorite which, while suppressing production cost, can effectively remove scale causing substances from desalinated concentrated water derived from high salt-containing waste water and efficiently provide high concentration sodium hypochlorite.SOLUTION: Provided is a method for producing sodium hypochlorite comprising: a softening treatment step where desalinated concentrated water derived from high salt-containing waste water is subjected to a softening treatment in an unsaturated state showing a prescribed chlorine ion concentration to reduce the concentration of calcium; an electrolysis step where, from the desalinated concentrated water subjected to the softening treatment in the softening step, caustic soda and a chlorine gas are generated using an ion exchange membrane method; and a sodium hypochlorite synthesizing step where sodium hypochlorite is synthesized from the caustic soda and chlorine gas generated in the electrolysis step. The softening treatment step includes: a first softening treatment step where the concentration of calcium is reduced relative to the desalinated concentrated water by a precipitation process; and a second softening treatment step where the concentration of calcium is further reduced by a chelate adsorption method after the first softening treatment step.SELECTED DRAWING: Figure 1