Research on the Ammonia Removal from Synthetic Wastewater by Electrodialysis and Electrodeionization

In this work, the technical capabilities of lab-scale electrodialysis (ED) and the electrodeionization (EDI) processes on removing ammonia from synthetic wastewater were investigated. The overall performance of ED and EDI process in the removal of ammonia from high ammonia concentration synthetic wastewater was assessed by applied electric potential, feed concentration, and energy consumption. Under the conditions of working electric potential, ED showed that ammonia concentration could be reduced from 1,000 to 309 mg/L with a best removal efficiency of 69.1%, EDI showed that the ammonia concentration could be reduced from 1,000 to 120.9 mg/L with a best removal efficiency of 87.91%, the energy consumption of ED and EDI were in the range of 1.7–12.96 Wh/L and 6.2–149.2 Wh/L, respectively. Under the conditions of feed concentration, ED and EDI obtained a best removal efficiency of 57.93% and 98.5%, respectively, the energy consumption was in the range of 9.36–53.55 Wh/L and 62.7–218.1 Wh/L, respectively, excessive applied electric potential and concentration will lower current efficiency and increase energy consumption. The ammonia removal efficiency of EDI was found to be higher than ED, but the current efficiency of EDI was lower than ED, and the stack current of EDI increased quickly under constant voltage when the feed concentration was over 1,000 mg/L. The results showed that EDI was suitable for low concentration solution treatment, whereas ED was suitable for high concentration solution treatment. As a novel technology of groundwater contamination treatment, the process was proved to be feasible and provided foundation for further research.