Wastewater New York State Practice Exam

What microorganism should ideally accompany Nocardia in a healthy activated sludge system?

1. Filamentous bacteria

2. Mastigophora

3. Floc-forming bacteria

4. Amoeba

The correct answer is: Mastigophora

In a healthy activated sludge system, the ideal microorganism to accompany Nocardia is Mastigophora. Mastigophora includes flagellated protozoa that play an essential role in the microbial ecosystem of wastewater treatment systems. These microorganisms are beneficial as they help in the degradation of organic matter and contribute to the overall stability and efficiency of the sludge. Mastigophora can assist in the digestion of specific substrates that might be less effectively processed by other microbial communities. Their presence in the system can also indicate good settling characteristics of the activated sludge, which is crucial for effective separation of treated water from biomass. The interaction between Mastigophora and filamentous bacteria, as well as other microorganisms, can promote a balanced microbial community. Filamentous bacteria may sometimes be problematic if they overgrow and lead to foaming or poor settling characteristics, while floc-forming bacteria play important roles in creating stable aggregates but do not provide the same type of synergetic benefits as flagellated protozoa. Amoeba can help control filamentous growth, but their role is more of a regulatory nature rather than one that supports stability like Mastigophora does. Thus, the presence of Mastigophora alongside Nocardia is