Shock Electrodialysis and Other Electrochemical Water Purification Methods

Large-scale seawater desalination is essentially a solved problem, despite its inherent cost, as reverse osmosis plants approach the thermodynamic efficiency limit. In contrast, grand challenges remain in how to efficiently treat lower salinity feedwater, e.g. from brackish sources, municipal waste, or industrial streams, in order to reduce salt, disinfect, remove toxins, and/or separate valuable chemicals with geographical flexibility and smaller, portable systems. Existing electrochemical methods, such as electrodialysis and capacitive deionization, can address some, but not all, of these needs. This talk will introduce a new process called "shock electrodialysis", which exploits deionization shock waves in charged porous media for continuous and simultaneous deionization, separations, and disinfection. The first shock ED prototype achieves 99.99% salt removal and up to 80% water recovery, although material optimization is still required to improve the energy efficiency and boost the flow rate.