Enhanced Electrolytic Removal of Ammonia from the Aqueous Phase with a Zeolite-Packed Electrolysis Reactor under a Continuous Mode

Abstract

This research investigated the mechanism and effect of influencing factors for aqueous ammonia removal by electrolysis in continuous mode with a zeolite-packed electrolysis reactor. Under the conditions of 30-min hydraulic retention time (HRT), 1.8-A current, and 300-mg/L chloride ion concentration, the ammonia concentration decreased from 25 to 0.3 mg N/L within 1.5 h electrolysis time. A total of 4.4 mg N/L nitrate, 0.03 mg N/L nitrite, and 0.3–0.8 mg N/L chloramines were detected in effluent, which accounted for 76% removal of total nitrogen from the aqueous phase. Moreover, the ammonia-presaturated zeolite was almost completely regenerated during the same time period. HRT, current, and chloride ion concentration were found to have a significant effect on ammonia removal as well as zeolite regeneration. Whereas other conditions were fixed, a minimum of 10-min HRT, 1.0-A current, and 210-mg/L chloride ion concentration were required to keep the effluent ammonia concentration below 1 mg N/L. For the treatment of municipal wastewater, minimum HRTs of 7.5, 11, and 21 min were suggested for initial ammonia concentrations of 13.5, 30.2, and 53.5 mg N/L under the conditions of 300-mg/L chloride and 1.8-A current.