Between two juxtaposed similar ion exchange membranes (AEMs or CEMs), an ion depletion zone and ion enrichment zone are generated under an electric field. As cations are selectively transferred through the CEMs, for example, anions are relocated in order to achieve electro-neutrality, resulting in the concentration drop (increase) in ion depletion (enrichment) zone. The use of a sacrificial metal anode allows electrocoagulation (EC) concurrently with ICP thereby permitting concentration of both ionic and non-ionic impurities to occur at the same time within the same cell or device.

Processes, systems, and techniques for multivalent ion desalination of a feed water use an apparatus that has a cathode, an anode, and an electrodialysis cell located between the cathode and anode. The cell has a product chamber through which the feed water flows, a multivalent cation concentrating chamber on a cathodic side of the product chamber through which the concentrated multivalent cation solution flows, and a multivalent anion concentrating chamber on an anodic side of the product chamber through which the concentrated multivalent anion solution flows. The product chamber and the multivalent cation concentrating chamber are each bounded by and share a cation exchange membrane, and the product chamber and the multivalent anion concentrating chamber are each bounded by and share an anion exchange membrane. A monovalent ion species is added to at least one of the concentrated multivalent cation solution and the concentrated multivalent anion solution.

Between two juxtaposed similar ion exchange membranes (AEMs or CEMs), an ion depletion zone and ion enrichment zone are generated under an electric field. As cations are selectively transferred through the CEMs, for example, anions are relocated in order to achieve electro-neutrality, resulting in the concentration drop (increase) in ion depletion (enrichment) zone. The use of a sacrificial metal anode allows electrocoagulation (EC) concurrently with ICP thereby permitting concentration of both ionic and non-ionic impurities to occur at the same time within the same cell or device.

The invention relates to an electrodialysis device for the desalination of water for oil and gas applications comprising: a membrane stack comprising alternating cation- and anion-exchange membranes (2.1, 2.3) and a plurality of spacers (2.2, 2.4), each spacer being arranged between two successive membranes; wherein at least one of the spacers (2.2, 2.4) comprises a recessed area (3.2) and a non-recessed area (3.3), a central opening (3.1) within the recessed area (3.2); the spacer (2.2, 2.4) is provided with at least four orifices (3.4, 3.5) within the non-recessed area (3.3); and with respective channels (3.6) which connect at least two of the orifices (3.4) with the central opening (3.1); and one membrane (2.1, 2.3) is accommodated in the recessed area (3.2). The invention also relates to a water desalination process using the electrodialysis device mentioned above.

This lithium recovery device 10C is provided with a processing tank 1 that is partitioned into a supply tank 11 and a recovery tank 13 by a lithium ion-conducting electrolyte membrane 2. In order to selectively move Li+ to an aqueous solution RS in the recovery tank 13 from an aqueous solution SW in the supply tank 11, the aqueous solution SW containing Li+ and other metal ions Mn+, this lithium recovery device 10C is also provided with: a first power supply 51 which is connected between a first electrode 31 that has a porous structure and is arranged so as to be in contact with a supply tank 11-side surface of the electrolyte membrane 2 and a second electrode 32A that is arranged within the recovery tank 13, in such a manner that the first electrode 31 functions as the positive electrode; and a sub power supply 53 which is connected in series to the positive electrode of the first power supply 51, while having the positive electrode thereof connected to a sub electrode 41 that is arranged within the supply tank 11 at a distance from the electrolyte membrane 2.