AIR STRIPPING FOR AMMONIA REMOVAL FROM LANDFILL LEACHATE IN VIETNAM: EFFECT OF OPERATION PARAMETERS
Abstract
Leachate is the wastewater from landfill that contains various pollutants at high concentrations. The treatment of leachate requires a complicated wastewater treatment system including chemical, physico-chemical, biological, and advanced treatment processes. The high ammonia concentration of leachate usually causes inhibition for microorganism in biological treatment. Therefore, it is necessary to remove ammonia from the leachate to lower concentrations to make it suitable for further treatment processes. In this study, we designed an air stripper for removal of ammonia in both synthetic and leachate wastewater. The effects of pH, hydraulic loading rate (HLR), gas/liquid (G/L) ratio, and recirculation of liquid on the ammonia stripping efficiency were investigated. The results show that rising pH from 9 to 12 increased significantly ammonia removal efficiency, irrespective of the changes of G/L or HLR. At both HLR of 57.6 and 172.8 m3/m2.day, increase G/L ratio led to the enhancement of removal efficiency, getting the highest value of 56% at HLR of 172.8 m3/m2.day, pH 12, and G/L of 728. Furthermore, recirculating of leachate improved the stripping efficiency of ammonia up to 99.0% after three hours with the output concentration of 25.2 mg/L. The results from this study hence proved the effectiveness of air stripping as a pre-treatment process for ammonia removal from landfill leachate and suggested suitable operating conditions.