Performance evaluation of resin wafer electrodeionization for enhanced nitrogen recovery from ammonium-containing water environment

Ammonium ion (NH₄⁺) is a common pollutant from various sources like human and animal waste, industrial effluents, agricultural runoff, and commercial products, with traditional treatment methods often generating secondary contaminants, such as nitrite and nitrate. In this study, an energy-efficient resin-wafer electrodeionization (RW-EDI) process was employed for nitrogen recovery from ammonium-rich water. The system was operated in a continuous mode, with voltage-current curve measurements identifying a limiting current density of 2.2 A cm⁻². With the NH₄⁺ concentration of 1 g/L and a flow rate of 2.4 mL min⁻¹, the system was tested at various cell voltages (1.2–7.2 V). The system could achieve 80 % NH₄⁺ removal efficiency at a cell voltage of 3 V, current density of 2.2 A cm⁻², influent NH₄⁺ level of 3 g/L, and flow rate of 6.4 mL min⁻¹. The observed current efficiency and the calculated power consumption were 41 % and 0.78 kWh m⁻³, respectively. Finally, a mass balance model was developed to predict the number of RW-EDI stacks for complete removal of NH₄⁺ from the feed. Overall, the result from this study demonstrates that the RW-EDI-based system could be a promising technology for recovering nitrogen from wastewater.