What is the term for the mixture of activated sludge and wastewater in the aeration basin?

The term for the mixture of activated sludge and wastewater in the aeration basin is known as mixed liquor. In wastewater treatment processes, particularly in activated sludge systems, mixed liquor is a crucial component. It refers to the biological mixture that includes microorganisms, organic matter, and nutrients.

In the aeration basin, air is introduced to promote the growth of these microorganisms, which feed on the organic pollutants in the wastewater, thus facilitating the treatment process. The term emphasizes the combined nature of the activated sludge and the incoming wastewater, highlighting the importance of biological activity for effective treatment.

Other terms, such as return sludge, which refers to the portion of sludge that is returned to the aeration basin from the secondary clarifier to maintain adequate biomass in the reactor, or primary sludge, which refers to the solids collected from the primary clarifier before biological treatment, do not accurately describe the active mixture occurring in the aeration basin. Settled sludge, on the other hand, relates to the solids that accumulate at the bottom of a clarifier after the biological treatment process, further distinguishing it from the mixed liquor in the aeration stage.