Intensified ammonia stripping from landfill leachate using a high-performance rotating reactor

Abstract

Rotating bed devices have proven their rapid and intensified mass transfer compared to conventional packed columns in separation processes, especially ammonia stripping. However, the prospect of implementing rotating bed devices for this purpose is still unclear since the previous data was only obtained from experiments with synthetic ammonia wastewater. Practical wastewater, such as landfill leachate, possesses various complex characteristics that have been reported to inhibit ammonia stripping efficiency. Therefore, this study was conducted to clarify the possibility of using the rotating bed device by investigating the stripping of ammonia from landfill leachate using the High-Performance Rotating Reactor (HP2R). The effect of parameters such as initial pH (pHi), rotational speed (ω), the gas-to-liquid flow rate ratio (QG/QL), and the liquid flow rate (QL) on the stripping efficiency (η) and volumetric liquid mass-transfer coefficient (KLa) was evaluated. The results of η and KLa varied from 17.1% to 71.8% and 0.0005 s−1 to 0.0039 s−1 at a controlled laboratory temperature of 30 °C under a variety of operational parameters. The ammonia stripping efficiency from leachate was slightly lower compared to the data of the synthetic wastewater experiment due to the solid particle formation from pre-alkalinization and precipitation of carbonate salts during the stripping process. The benefit of using HP2R over the conventional packed column in ammonia stripping was the improvement of η at lower pHi of 9.5 by optimizing the ω and QG/QL. Additional stripping cycles resulted in a higher ammonia stripping efficiency from leachate up to 94.6%.