Kinetics of Oxygen Dissolution and Modeling of the Aeration Process in Wastewater Treatment Bioreactors

Abstract

Aeration is a key and the most energy-intensive process in biological wastewater treatment using activated sludge systems in aeration tanks, accounting for up to 50-90% of the total energy consumption of wastewater treatment plants. The efficiency of biological treatment largely depends on providing activated sludge microorganisms with a sufficient concentration of dissolved oxygen as well as ensuring proper mixing of the sludge mixture within the reactor. Therefore, improving the efficiency of aeration systems is an important task for reducing operational costs and increasing the overall sustainability of wastewater treatment facilities. This paper examines the theoretical foundations of the aeration process in biological wastewater treatment systems. Particular attention is given to the mechanisms of oxygen mass transfer from the gas phase into the liquid phase and the factors influencing this process. The key parameters characterizing oxygen transfer efficiency are analyzed, including the volumetric oxygen mass transfer coefficient (KLa) and the α-factor, which reflects the influence of wastewater properties on oxygen transfer. Understanding these parameters is essential for the correct design, optimization, and operation of aeration systems in activated sludge reactors. The presented theoretical analysis contributes to improving the energy efficiency and operational performance of modern wastewater treatment plants.