| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an apparatus for recovering nitric acid efficiently from a nitric acid-containing treatment-targeted liquid and recycling the recovered nitric acid.SOLUTION: A method of treating a treatment-targeted liquid comprises a step of using a nitric acid separation facility 20 for separating a nitrate ion and a sulfate ion from liquid waste containing the nitrate ion and the sulfate ion. The nitric acid separation facility 20 is a recycle system for generating a sulfate ion-removed nitric acid aqueous solution and returning the generated nitric acid aqueous solution to the source of generating the liquid waste. The nitric acid separation facility 20 includes a first nitric acid separation part 23 having a reverse osmosis membrane, in which the liquid waste is separated into permeated water and concentrated water, as a main element. The reverse osmosis membrane is characterized in that a desalting rate R1 of the nitrate ion becomes smaller than that R2 of the sulfate ion in an acid range and the nitrate ion can be separated from the sulfate ion since a large number of the sulfate ions are included in the concentrated water and a large number of the nitrate ions are included in the permeated water when the liquid waste is treated in the reverse osmosis membrane.SELECTED DRAWING: Figure 2 |
