Method for treating waste water containing neutral salts comprising monovalent ions
First Claim
1. A method for treating waste water containing neutral salts containing monovalent ions, comprising the steps ofsupplying a feed stream to a prepositive electrodialysis cell;
- separating the neutral salts from the waste water by electrodialysis in the prepositive electrodialysis cell to obtain a concentrated stream and a diluted stream;
supplying the concentrated stream from the prepositive cell to an electrolytic dialysis cell for separating the neutral salts into acids and bases; and
supplying the diluted stream from the prepositive cell to at least two main electrodialysis cells, comprising a first stage and a final stage, combined in series for reducing the concentration of the neutral salts in the diluted stream.
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Accused Products
Abstract
In order to reduce releasing of neutral salts comprising monovalent ions contained in industrial waste effluent to the environment, the waste effluent to be treated is supplied into a prepositive electrodialysis cell comprising ion exchange membranes which transfer monovalent ions selectively for concentrating the salts, concentrated stream is supplied into an electrolytic dialysis cell for separating and recovering acids and bases, subsequently diluted stream is circulated as supplying stream to the prepositive electrodialysis cell, the diluted stream in said prepositive electrodialysis cell is subsequently supplied to and desalted by one or plural electrodialysis cells combined in series, the diluted stream after the desalination is released to the environment, and the concentrated stream is merged to the supplying stream to the prepositive electrodialysis cell. In accordance with the present invention, concentration of impurity in recovered acid decreases to less than 1/10, and necessary electric power for dialysis treatment and recovery of the acid and the base decreases to less than 1/2.
24 Citations
20 Claims
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1. A method for treating waste water containing neutral salts containing monovalent ions, comprising the steps of
supplying a feed stream to a prepositive electrodialysis cell; -
separating the neutral salts from the waste water by electrodialysis in the prepositive electrodialysis cell to obtain a concentrated stream and a diluted stream; supplying the concentrated stream from the prepositive cell to an electrolytic dialysis cell for separating the neutral salts into acids and bases; and supplying the diluted stream from the prepositive cell to at least two main electrodialysis cells, comprising a first stage and a final stage, combined in series for reducing the concentration of the neutral salts in the diluted stream. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification