Gas transfer model for a multistage vortex aerator: A novel oxygen transfer system for dissolved oxygen improvement

A novel aerator for enhancing the oxygen transfer rate and efficiency, named multistage vortex aerator (MVA), was developed. It uses vortex flow in repeated stages to increase the gas-liquid interfacial area and to decrease the thickness of the stagnant layer at the interface between the two phases. The basic characteristics of oxygen transfer using this aerator were investigated using the American Society of Civil Engineers standard procedure. The MVA could rapidly transfer oxygen to water to a concentration higher than 40 mg/L in 60 min owing to the effect of high purity oxygen, additional pressure induced by water and gas, and vortex flow dynamics. A gas transfer model was developed for describing the non-steady state operation of the aerator. This model is based on the mass and molar balances of oxygen in gas and water. It could successfully simulate the DO change inside the aerator. This study can help better understand the oxygen transfer mechanism and evaluate the performance of the new aerator at the various temperatures, pressures, and gas compositions found in diverse environmental systems. [Display omitted] •We present an aerator that uses vortex flow and oxygen to enhance oxygen transfer.•The DO concentration exceeded 40 mg/L in 60 min at Qo2 3.0 L/min, T = 24 °C.•Standard oxygen transfer efficiency exceeded 50% without any tall tower.•Gas transfer model based on oxygen mass/molar balances in gas and water is provided.•The model is able to simulate performance of the aerator in diverse conditions.