To provide a method for preventing the capacity reduction of a discharging water-treating process caused by the discharging water formed in the process of recovering an aqueous alkali metal oxide solution of a high purity aromatic dihydroxy compound in treating waste aromatic polycarbonate resin (e.g. disused articles from aromatic polycarbonate products such as information media materials such as CDs, the head lamps, sheets, etc., of automobiles) inexpensively in a large amount.

This method for recovering the aqueous alkali metal hydroxide solution of the aromatic dihydroxide compound by dissolving the waste aromatic polycarbonate resin with an organic solvent and decomposing the polycarbonate resin in the organic solvent solution in the presence of an aqueous alkali metal hydroxide solution is characterized by heating the discharging water formed in recovering the aqueous alkali metal hydroxide solution of the aromatic dihydroxide from the waste aromatic polycarbonate resin at or higher than the boiling point of the used organic solvent, removing solid parts precipitated in the discharging water, and then performing the waste water treatment.

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