Wastewater aeration is the process of adding air to wastewater to allow aerobic biodegradation of pollutant components. It is an integral part of most biological wastewater treatment systems. Unlike chemical treatment that uses chemicals to react and stabilize contaminants in the wastewater stream, biological treatment uses microorganisms that occur naturally in wastewater to degrade wastewater contaminants.

Aeration is the most critical component of a treatment system using the activated sludge treatment process. A well-designed aeration system has a direct impact on the level of wastewater treatment it achieves. A wide and evenly distributed distribution of oxygen in an aeration system is the key to rapid, economically viable and efficient wastewater treatment.