Zoogloeal mass is best described as which of the following?

• A. A type of algae in wetlands
• B. A chemical additive used in primary treatment
• C. A sludge thickener
• D. Jelly-like mass of bacteria found in trickling filters or activated sludge process

Answer: (D)

Zoogloeal mass is a gelatinous, jelly-like aggregation of bacteria that forms in wastewater treatment systems. It comes from bacteria such as Zoogloea producing a mucilaginous extracellular matrix, which binds cells and solids into a cohesive mass. In trickling filters and activated sludge processes, this bacterial mass can appear as a visible, jelly-like clump and plays a role in how solids are trapped and flocculate. It’s a biological phenomenon, not an algae, not a chemical additive, and not a sludge thickener device. That jelly-like bacterial mass description best matches what zoogloeal mass is.