Florida Wastewater Practice Test

What condition do low DO and nutrient deficiencies promote the growth of?

1. Pathogenic bacteria

2. Filamentous bacteria

3. Aerobic bacteria

4. Sludge organisms

The correct answer is: Filamentous bacteria

Low dissolved oxygen (DO) levels and nutrient deficiencies create an environment that is conducive to the growth of filamentous bacteria. Under such conditions, aerobic processes are hindered due to the lack of oxygen, which often leads to a shift in the microbial community. Filamentous bacteria thrive in low-DO environments because they can use alternative metabolic pathways that do not rely on oxygen. These organisms, characterized by their thread-like structure, can form mats or filaments, particularly in activated sludge systems, which can have implications for wastewater treatment, including settling problems. The nutrient deficiencies may also stress the system, allowing filamentous bacteria to outcompete other microbial populations that are more dependent on aerobic conditions or adequate nutrient availability. This interplay of low DO and nutrient balance is essential for understanding microbial dynamics in wastewater treatment processes.