Enhancing the efficiency of electrodialysis brine concentrator to reduce the levelized cost of salt production through dynamic model-based simulations

Electrodialysis (ED) is a membrane-based, electro-driven desalination technology that treats nontraditional water for fit-for-purpose applications. Modern ED systems could play a crucial role in brine valorization because the resulting diluate and concentrate streams can be tailored to generate unique water chemistries with valuable end-uses. ED brine concentrator (EDBC) is an emerging technology developed to cost-effectively concentrate brine up to 200 g/L salts in lieu of energy-intensive conventional thermal brine concentrators. This study developed a semi-empirical dynamic model based on bench-scale batch and steady-state experiments to explore the potential and limitations of EDBC and to optimize operational conditions and system performance. In addition to optimizing the experimental conditions, this study examines the influence of channel height (spacer thickness) on EDBC performance. The experimental and model simulation results reveal that reducing the channel height by half (from 0.076 cm to 0.038 cm) enhanced the salt migration in EDBC by 11.1 %. After system optimization and scaling up to a full-scale single-pass configuration treating 378.5 m3/d of brine, the technoeconomic assessment estimated specific energy consumption and a levelized cost of salts of the EDBC to be 0.18 kWh/kg and $0.86/kg of salts transported, respectively. Following these optimizations, the system effectively concentrates the brine from 50 g/L to 200 g/L while producing a diluate with a salt concentration of 200 mg/L for beneficial reuse. This study demonstrates that desalinated water production while brine solution production via EDBC is more energy and cost-efficient than emerging low salt rejection reverse osmosis and falling film evaporators methods.