Recycle loop for reduced scaling in bipolar membrane electrodialysis

1. A method comprising:

introducing seawater into an electrodialysis unit comprising at least one cell comprising a basified solution compartment, a bipolar membrane, an acidified solution compartment and an anion exchange membrane, wherein the seawater is introduced into the acidified solution compartment;

acidifying the seawater;

removing acidified seawater from the acidified solution compartment;

removing CO 2 from the acidified seawater to form a decarbonized seawater; and

introducing the decarbonized seawater into the basified solution compartment of the electrodialysis unit.

2. The method of claim 1 , wherein acidifying the seawater comprises applying a voltage to the at least one cell.

3. The method of claim 1 , wherein the electrodialysis unit comprises cells with a bipolar membrane (BPM) compartment, a cation exchange membrane (CEM), and an anion exchange membrane (AEM), and where in addition to an acid and a base stream, a desalinated stream also exits from the electrodialysis unit.

4. The method of claim 1 , wherein removing the CO 2 from the acidified seawater comprises vacuum stripping of the CO 2 from the acidified seawater.

5. The method of claim 4 , further comprising capturing the CO 2 .

6. The method of claim 1 , further comprising introducing untreated seawater with the decarbonized seawater into the basified solution compartment of the electrodialysis unit.

7. A method comprising:

introducing sea water into an electrodialysis unit comprising at least one cell comprising a basified solution compartment and an acidified solution compartment and an anion exchange membrane, wherein the seawater is introduced into the acidified solution compartment;

acidifying the seawater to generate carbon dioxide (CO 2 );

removing acidified seawater from the acidified solution compartment;

removing the CO 2 from the acidified seawater to form decarbonized seawater;

introducing in a first instance, untreated seawater into the basified solution compartment of the electrodialysis unit and, in a second instance, the decarbonized seawater into the basified solution compartment of the electrodialysis unit; and

collecting the CO 2 .

8. The method of claim 7 , wherein removing the CO 2 from the acidified seawater comprises vacuum stripping of the CO 2 from the acidified seawater.

9. The method of claim 7 , wherein in the second instance, introducing both the untreated seawater and the decarbonized seawater into the basified solution compartment.

10. A system comprising:

an electrodialysis unit comprising an acidified solution compartment, a basified solution compartment, a bipolar membrane, an input to the acidified solution compartment and an input to the basified solution compartment; and

a desorption unit coupled to an output of the acidified solution compartment, the desorption unit operable to remove CO 2 from a solution from the acidified solution compartment, the desorption unit comprising a solution output that is coupled to the input to the basified solution compartment.

11. The system of claim 10 , wherein the electrodialysis unit comprises a seawater source coupled to the input to the acidified solution compartment.

12. The system of claim 10 , wherein the electrodialysis unit comprises an untreated seawater source coupled to the input to the basified solution compartment.

13. The system of claim 12 , wherein the system is operable to introduce a solution from the untreated seawater source along with a solution from the desorption unit solution output into the basified solution compartment.

14. The system of claim 12 , further comprising a controller operable to control the flow of a solution from the untreated seawater source and a solution from the desorption unit solution output into the basified solution compartment.