In secondary suspended growth processes, what is the purpose of aeration tanks?

The purpose of aeration tanks in secondary suspended growth processes is to facilitate the growth of aerobic bacteria. These tanks are designed to introduce air into the wastewater, providing the necessary oxygen for aerobic microorganisms to thrive. These bacteria play a crucial role in breaking down organic matter present in the wastewater, leading to the reduction of pollutants before the treatment continues.

Aerobic bacteria consume organic pollutants as part of their metabolic processes, which results in the production of carbon dioxide, water, and additional biomass. This biological treatment is vital for achieving the desired effluent quality, as it helps to significantly reduce biochemical oxygen demand (BOD) and other organic contaminants.

In contrast, increasing the temperature of the water or cooling it before discharge does not directly relate to the function of aeration tanks. Similarly, while some processes may involve the removal of heavy metals, it is not the primary role of the aeration step in secondary treatment, where the focus is on organic matter degradation through the action of aerobic bacteria.