Why is it necessary to control the mixed liquor solids in an aerator?

Controlling mixed liquor solids in an aerator is vital primarily to maintain the proper biochemical oxygen demand (BOD) in the treatment process. Mixed liquor solids, which consist of microorganisms and settled sludge, play a crucial role in breaking down organic matter in wastewater. If the mixed liquor is either too concentrated or too diluted, it can lead to inefficiencies in the biological processes that consume oxygen and reduce BOD. Maintaining the right concentration of mixed liquor solids ensures that there are enough microorganisms to effectively degrade organic pollutants while optimizing oxygen transfer and overall treatment efficiency.

While other factors like odor production, settlement efficiency, and filamentous growth are also important aspects of wastewater treatment, they are more often results of how well the mixed liquor solids are managed rather than direct reasons to control them. Therefore, focusing on the management of mixed liquor solids fundamentally supports the goal of maintaining proper BOD levels, which is essential for effective wastewater treatment.