Energy Recovery and Process Design in Continuous Flow–Electrode Capacitive Deionization Processes

Flow-electrode capacitive deionization (FCDI) is an electrically driven water desalination process based on the adsorption of ions in pumpable carbon flow-electrodes, also called slurry electrodes, which act as an electrical double-layer capacitor. The pumpability of the electrodes enables a fully continuous operation of FCDI and a whole range of new process designs in contrast to capacitive deionization processes based on static electrodes. In this work, we demonstrate continuous energy recovery of up to 36% of the energy applied during the desalination step during the regeneration of the carbon flow-electrodes. The process performance and energy demand for desalination and pumping of the flow-electrodes are investigated for different FCDI process layouts. The potential of FCDI systems is compared to state-of-the-art desalination methods regarding the energy demand. The energy demand and influence of specific process parameters, such as the applied voltage and the feedwater salinity, are discussed on the...