Tennessee Wastewater Operator Practice Exam

What concentration of dissolved oxygen (DO) is necessary to prevent the growth of low DO filaments?

1. 1 mg/L

2. 2 mg/L

3. 3 mg/L

4. 4 mg/L

The correct answer is: 2 mg/L

To effectively prevent the growth of low dissolved oxygen (DO) filaments, it is essential to maintain a concentration of at least 2 mg/L of dissolved oxygen in wastewater treatment systems. Below this threshold, conditions may favor the proliferation of filamentous organisms that thrive in low-oxygen environments, which can lead to issues such as poor settling characteristics and increased sludge volume in the treatment process. By ensuring that the DO concentration is kept at 2 mg/L or higher, operators can create an environment that supports the growth of more beneficial microorganisms that require adequate oxygen levels for aerobic respiration, thus promoting a balanced and healthier biomass in the treatment system. This concentration acts as a critical threshold for maintaining operational efficiency and preventing the negative impacts associated with filamentous growth.