Off-Gas Treatment of Ammonia Using a Diffused Air Stripper: A Kinetic Study

The presence of excess ammonia nitrogen in aqueous environments has caused various problems such as eutrophication, oxygen depletion and aquatic toxicity. Hence, it is necessary to have special consideration in the discharge of ammonia to environment. The aim of this study was to study kinetic of ammonia degasification at a short-time (6 hours) with relatively constant pH and temperature. Ammonia degassing was carried out using a diffused air stripper. The unit consisted of 1 L cylindrical column with dimension of 30 × 8 cm. The flow rate was set at 2 L/minute at 6 hours. The operating parameters such as ammonia, nitrate, nitrite, electrical conductivity (EC), the oxidation-reduction potential (ORP), and pH were analyzed according to standard methods. According to obtained results, the maximum removal efficiencies were determined 17%, 35.5%, 31%, 66%, and 85.5%, for 50, 100, 200, 500 and 1000 mg/L ammonia concentrations, respectively. A first-order kinetic model was adopted to represent the ammonia degassing. The ammonia degassing is a simple and suitable technology for ammonia removal at high concentration. Undesirable removal efficiency (17%, 35.5% and 31%) can be occurred in suitable pH 11 in the presence of lower ammonia concentrations (50, 100 and 200 mg/L).