| 摘要 |
PURPOSE:To recover highly concentrated acids economically and efficiently, by introducing filtered liquids separated by neutralization and precipitation after deacidifying acidic waste liquids containing mineral acids and their metallic salts into an electrodialysis device comprising bipolar membranes and ion-exchange membranes to regenerate acids and alkalis. CONSTITUTION:Acidic waste liquid 9 containing mineral acids and their metallic salts is supplied to a deacidifying room (a dialysis room) of an ion-exchange membrane electrodialysis device or a diffusion dialysis device 1, while dilute acid is supplied to a concentration room (diffusion room) 2, causing acids in acidic waste liquid 9 to be selectively transferred to the concentration room 2. And deacidified liquid 10 having decreased acid concentration is fed to a neutralization precipitator II, where the liquid 10 is neutralized by alkaline liquid 12, causing metallic salts in the liquid to precipitate as hydroxides, whereby sludge and slurry 13 are obtained. The neutralized, separated liquid 14 is fed to an intermediate room 6 of an ion-exchange membrane electrodialysis device III wherein cation exchange membranes 3, bipolar membranes 4, and anion exchange membranes 5 are arranged in series, whereby highly concentrated alkalis is obtained through the bipolar membranes 4 from a base room 8 and highly concentrated acids from a acid producing room 7. |
