What is the purpose of recycling thickened activated sludge?

Recycling thickened activated sludge serves a crucial function in wastewater treatment processes by helping to maintain a stable population of microorganisms, which are essential for effective biological treatment. When thickened sludge is returned to the aeration tank, it reinvigorates the microbial community responsible for breaking down organic matter in the wastewater. These microorganisms are vital for the biochemical processes that degrade pollutants, and their stability ensures that the treatment process operates efficiently over time.

The recycling process promotes the continuity of active biomass in the system, allowing the treatment facility to respond effectively to variations in influent quality and flow. By sustaining a healthy population of microorganisms, the treatment plant is better equipped to handle fluctuations in loading and can maintain optimal performance levels in removing contaminants.

In contrast, reducing odor, integrating chemicals, or improving the aesthetic quality of sludge does not directly benefit the biological treatment efficiency as recycling does. These factors can be influenced by other treatments or processes that do not focus specifically on maintaining microbial populations.