Which of the following is not associated with an aeration tank?

When considering the components typically associated with an aeration tank, it is important to understand the primary role of these tanks in the wastewater treatment process. Aeration tanks are designed to promote the growth of aerobic bacteria, which are essential for the breakdown of organic matter found in wastewater.

Activated sludge is a mixture of water, microorganisms, and organic matter in the aeration tank. This mixture is aerated to facilitate the aerobic degradation of pollutants. As oxygen is supplied to the tank, the aerobic bacteria consume the organic materials, helping to purify the water.

Oxygen diffusion is also a critical aspect of aeration tanks. It involves the introduction of air or oxygen into the tank to ensure that the aerobic bacteria have the necessary oxygen to thrive and effectively treat the wastewater.

However, rotating biological contactors (RBC) are a separate type of wastewater treatment system that uses a different method involving rotating disks to provide surface area for biofilm growth. While RBC systems may have some similarities to aeration tanks in terms of functioning within a biological treatment framework, they do not directly occur within an aeration tank setup. Therefore, RBC is not associated with the specific processes conducted within an aeration tank.