Seawater predesalination with electrodialysis

The suitability of ED for seawater desalination was investigated and we quantified the energy losses that play a role in electrodialysis. The combination of electrodialysis (ED) and brackish water reverse osmosis (BWRO) is presented as an alternative desalination strategy for seawater reverse osmosis (SWRO). Experiments have been performed with a recycling batch electrodialyzer. From this we conclude that in most cases the membrane stack is responsible for the main energy loss in the system. Energy losses due to water transport are generally low. At low applied current density, osmotic water transport is relatively large and as such the energy loss, while electroosmosis was found to be directly proportional to the applied current density. The relative energy loss caused by back diffusion was found to be only of minor importance for higher current densities and was only more pronounced at the lowest applied current density of 10 A/m(2). Combining ED with BWRO in a hybrid system does not lead to a reduction in energy consumption compared to ED as standalone technique, when the applied current density becomes lower than 50 A/m(2). At low applied current density (10 A/m(2)) ED can perform desalination energetically cheaper at lower operational costs than SWRO. (C) 2013 Elsevier B.V. All rights reserved.