What does the activated sludge process in wastewater treatment involve?

The activated sludge process is a crucial method used in the secondary treatment phase of wastewater treatment that involves aerating wastewater to promote biological decomposition of organic matter. In this process, wastewater is mixed with a controlled population of microorganisms, primarily bacteria, which consume the organic pollutants present in the water.

Aeration provides the oxygen necessary for these microorganisms to thrive and facilitates the breakdown of organic materials. As the microorganisms metabolize the organic matter, they grow and multiply, forming a floc or sludge that can then be separated from the treated water in a secondary clarifier. This biological treatment is effective in reducing biochemical oxygen demand (BOD) and suspended solids in the wastewater.

The activated sludge process is particularly effective because it allows for the continuous recycling of a portion of the biomass, enabling a stable microbial community that can respond efficiently to variations in wastewater composition. Therefore, the correct answer accurately reflects the key functions and characteristics of the activated sludge process in wastewater management.