In terms of sludge thickening, wasted activated sludge (WAS) typically can be described as ___________

Wasted activated sludge (WAS) is characterized by its tendency to form a light, fluffy floc that does not settle well. This property stems from the nature of the biological process in activated sludge systems, where microorganisms develop a more delicate structure. The light and fluffy nature of the floc indicates that it contains a higher amount of water and has a reduced density compared to denser, compact sludge.

As a result, this type of floc can be challenging during the thickening or settling process because the particles do not have the weight necessary to settle quickly beneath the water column. This characteristic is important in the management and treatment of wastewater, as effective sludge handling relies on the ability to thicken and dewater sludge efficiently. Understanding the behavior of WAS helps operators optimize processes such as thickening and ensure proper handling in the treatment system.

In contrast, the other options present different attributes unrelated to the typical characteristics of WAS. For example, compacting easily and having a low sludge volume index are features more aligned with denser sludge or well-settling sludge, while settling rapidly is indicative of sludge that is more compact and less flocculent.