Tennessee Wastewater Operator Practice Exam

Which type of foam is primarily associated with Microthrix parvicella?

1. Stable, viscous brown foam

2. Thin, white foam

3. Bubbly, white foam with odors

4. Frothy, green foam

The correct answer is: Stable, viscous brown foam

Microthrix parvicella is a filamentous bacterium often associated with wastewater treatment systems, particularly in activated sludge processes. This microorganism tends to produce stable, viscous brown foam, which is a common problem in wastewater treatment plants experiencing filamentous bulking. The reason stable, viscous brown foam is specifically indicative of Microthrix parvicella is due to the organism's ability to thrive in environments with high organic loading and low nutrient availability, resulting in the generation of this characteristic foam. The foam is not only visually distinct but also tends to be more resistant to collapse compared to other types of foams produced by different organisms. Understanding the type of foam helps operators identify potential issues in the treatment process, as the presence of this stable foam could lead to operational inefficiencies, hindered treatment performance, and the need for process adjustments to manage the growth of Microthrix parvicella effectively.