Florida Wastewater Practice Test

Low dissolved oxygen (DO) and nutrient deficiency promote the growth of what?

1. Pathogenic bacteria

2. Filamentous bacteria

3. Sludge worms

4. Algae

The correct answer is: Filamentous bacteria

The correct choice highlights that low dissolved oxygen (DO) levels and nutrient deficiency create an environment that favors the growth of filamentous bacteria. These bacteria thrive in conditions where organic matter decomposition is occurring at a high rate, typically in stagnant or overloaded wastewater systems. When nutrient levels, particularly nitrogen and phosphorus, are low, it can lead to a specific form of nutrient limitation that may cause some microorganisms, like filamentous bacteria, to proliferate as they can utilize the limited resources efficiently. Additionally, low oxygen levels can further enhance the dominance of filamentous forms because they can tolerate or even prefer anaerobic conditions, which can occur when dissolved oxygen is not sufficient. These bacteria have a unique morphology that aids in their management within treatment systems, often forming long filaments that can contribute to bulking in activated sludge processes. Understanding the interplay between dissolved oxygen levels, nutrient availability, and the types of bacteria that thrive under these conditions is crucial for effective wastewater treatment management. This relationship is often a key factor in addressing operational challenges in wastewater treatment facilities.