Evaluation of ammonia–nitrogen removal efficiency from aqueous solutions by ultrasonic irradiation in short sonication periods

In this study, mechanisms and efficiency of ammonia–nitrogen removal from aqueous solutions by ultrasonic irradiation were investigated. Depending on the factors affecting the sonication (initial concentration, initial pH, ultrasonic power density, and sonication period), sonication tests were carried out and ammonium–nitrogen removal efficiency by ultrasonic irradiation was determined. In these experiments, ammonia–nitrogen removal efficiency was achieved in the range of 8–64%. In short sonication periods, the best ammonia–nitrogen removal efficiency was achieved at pH 8.2–11. Lower ammonia–nitrogen removal efficiency was observed in high initial ammonia–nitrogen concentration solutions. It was observed that high initial ammonia–nitrogen concentrations may lead to decreased ammonia–nitrogen removal efficiency; however, the quantity of ammonia–nitrogen removal was higher. Because high initial concentration had a negative impact on the sonochemical reactions, the heat of cavitation bubbles was reduced. Ammonia–nitrogen removal efficiency was increased with ultrasonic density and sonication period. This study showed that effective ammonia–nitrogen removal could be achieved by ultrasonic irradiation in short sonication periods (as 60–600 s). Specific cost of ammonia–nitrogen removal by ultrasonic irradiation from simulated groundwater, surface water, wastewater, and landfill leachate was also calculated. The specific removal cost varied between 0.01 and 0.25 $/g ammonia–nitrogen.