The final step is a second stage of reverse osmosis, linked directly to an electro-deionisation system, which is used to extract the last remnants of dissolved minerals (ions). The salts are retained by an ion exchange resin, which would usually be regenerated with acid and lye. With electro-deionisation, however, the ions of the resin are drawn to the outside by means of an electrical potential difference. The special membranes only allow charged ions to pass through, as a result of which the last remaining salt can be disposed of via side channels.
After this final step, the water has a purity of approx. < 0.065 µs/cm. Via its very own pipeline, it is then transported to the steam system of the nearby oilfield.
