Development of a four-grade and four-segment electrodialysis setup for desalination of polymer-flooding produced water

An electrodialysis (ED) setup with an 11 m3/h water treatment scale was designed based on a small experimental device. The setup adopts four-grade and four-segment (four-GS) reversal electrodialysis (EDR) technology to desalinate polymer-flooding produced water (PFPW). The removal rate of total dissolved solids (TDS) with different flow rates was measured with different grades and segments. The operating performance of this setup was determined to meet design standards. The maximum treatment capacity and the optimal operation conditions of the tested setup were studied. The design standards were met only by adopting a four-GS ED setup. The maximal capacity of the four-GS ED setup for treating PFPW was 5 m3/h. The optimal operating condition and results were at an operating electric current of 86 A, 62.5% production rate of diluted treated PFPW, 0.89 kW∙h/m3 energy consumption, and 78.7% TDS removal rate. Under optimal conditions, the treated PFPW has two beneficial uses. First, the diluted treated PFPW is feasible for preparing polymer solutions. Second, the concentrated treated PFPW is feasible for replacing the original PFPW as the injecting water in the water-flooding process for high permeability layers.