What common term do operators use to refer to MLSS?

The term that operators commonly use to refer to Mixed Liquor Suspended Solids (MLSS) is "bugs." This informal terminology originates from the role that microorganisms, particularly bacteria, play in the biological treatment of wastewater. In the activated sludge process, for example, these "bugs" are crucial for breaking down organic matter and promoting the overall treatment efficiency. They contribute to the formation of a biomass, which is measured in terms of MLSS, indicating the total mass of suspended solids in the mixed liquor of the aeration tank. By using the term "bugs," operators emphasize the biological aspect of wastewater treatment and the active role these microorganisms have in the process.

While "flocs" refers specifically to clusters of microorganisms that settle out of the mixed liquor during the sedimentation process, and "particles" or "granules" might refer to solids in a broader context, "bugs" captures the essence of the living organisms that drive biological treatment. Thus, the use of "bugs" reflects both a practical understanding and a more familiar terminology within the field of wastewater treatment.