Air stripping of ammonia using a gas-liquid contactor: Effect of pH, temperature, airflow rate, and initial ammonia concentration

Abstract

Ammonia is one of the most important parameters to be considered in the treatment of domestic and industrial wastewater. If the ammonia discharged to receiver media (river, lake, and sea) is not treated, it may cause environmental problems. The present study examines the impact of pH, airflow rate, initial ammonia concentration, and temperature on ammonia stripping by using air stripping with a gas-liquid contactor. In the system operated in batch mode, the operations were conducted with fixed pH throughout the stripping period (360 min.) and the optimum pH level was determined to be 11. It was shown that high airflow rate and temperature have significant effects on ammonia stripping efficiency and overall volumetric mass transfer coefficient (𝐾𝐿𝑎). When removing ammonia by altering the initial ammonia concentration, no significant changes were observed in ammonia stripping efficiency and 𝐾𝐿𝑎. With pH of 11, initial ammonia concentration of 100 mg/L, airflow rate of 20 L/min, and temperature of 55 °C, it was determined that removal of ammonia took approximately 90 min. and the highest overall volumetric mass transfer coefficient for this setting was found to be 0.0462 min-1.