Treatment method and device of liquid waste containing inorganic salt

Abstract

The invention relates to a treatment method and device of liquid waste containing inorganic salt. The treatment method and device fully remove the impurities contained in the liquid waste containing inorganic salt and recycle high-quality acid and alkali at low cost. The device is provided with an impurity removing device (10) for removing the impurities from the liquid waste containing inorganic salt and an electrodialysis device (20) for separating the treated liquid waste into acid solution and alkali solution through electrodialysis and recycling the acid solution and the alkali solution, wherein the impurity removing device (10) is provided with a crystallization device (12), a salt separation device (13), a dissolving tank (14) and a concentration device (15); the crystallization device (12) is used for precipitating the inorganic salt in the liquid waste; the salt separation device (13) is used for separating the precipitated inorganic salt from the filtrate; the dissolving tank (14) is used for generating the solution of the separated inorganic salt; and the concentration device (15) is used for evaporating and concentrating the filtrate generated in the salt separation device to supply the concentrated filtrate generated in the concentration device to the crystallization device (12).

Description

technical field [0001] The invention relates to a treatment method and device for treating inorganic salt-containing waste liquid such as factory drainage and leaching water. Background technique [0002] As a method for treating waste liquids containing various inorganic salts such as sodium sulfate (glauber's salt) and sodium chloride, a method of recovering acids and alkalis from waste liquids using an electrodialysis device has been known. For example, in Patent Document 1, a method is disclosed in which alkaline waste liquid of sulfate is subjected to dealkalization treatment and then supplied to an ion-exchange membrane electrodialysis device, thereby inhibiting the anion-exchange membrane of the electrodialysis device from worse. [0003] Patent Document 1: Japanese Patent No. 3015486 Contents of the invention [0004] However, for the treatment method disclosed in Patent Document 1, the pretreatment for supplying the waste liquid to the electrodialysis device is ...

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Problems solved by technology

[0005] In addition, due to the presence of impurities such as chloride ions, nitrate ions, and hydrofluoric acid ions that were difficult to remove through conventional pretreatments, hydrochloric acid, nitric acid, and hydrofluoric acid, etc. will be mixed into the recovered sulfuric acid, and it is easy to become a highly corrosive acid. Therefore, from the viewpoint of maintaining corrosion resistance, there is also a problem that the material cost of the equipment and the cost of the production line are increased.

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