Energy-efficient resin wafer electrodeionization for impaired water reclamation

Abstract

A robust ion-exchange resin wafer electrodeionization technology was used to demonstrate the energy efficiency of impaired water desalination. The loose ion exchange resin beads used in conventional electrodeionization were immobilized and molded to form a porous resin wafer material. In this study, the energy efficiency of brackish water desalination using resin wafer electrodeionization was evaluated along with salt removal ratio, current efficiency and productivity. Several key operating factors, including treatment time, applied electrical energy and feed flow rate were selected through experimental design. In addition, the removal rate constant in resin wafer electrodeionization was determined via a pseudo first-order kinetic model, and then correlated with operation parameters. Furthermore, the prediction models of the productivity and energy consumption were established using response surface methodology. Results suggest that resin wafer electrodeionization can improve energy efficiency to greater than 35% in comparison to reverse osmosis (normally ∼12%) for impaired water desalination. The energy consumption of resin wafer electrodeionization was found to be 0.35–0.66 kWh/m3 with productivity of 20.1–44.7 L/hr/m2 (i.e., 5.3–11.8 gal/hr/m2) for brackish water desalination. Furthermore, a preliminary economic evaluation on impaired water desalination using resin wafer electrodeionization comparable to commercial reverse osmosis process was provided. It suggests that resin wafer electrodeionization offers the potential for an abundant source of fresh water from impaired water desalination at a cost-effective manner, which should be viewed as a crucial component in the portfolio of water supply options.