Basic Wastewater Operator Practice Exam

What is a common indicator of biological activity in a treatment plant?

1. Temperature

2. pH level

3. Dissolved oxygen content

4. Turbidity

The correct answer is: Dissolved oxygen content

Dissolved oxygen content serves as a vital indicator of biological activity in a wastewater treatment plant because it reflects the amount of oxygen available for aerobic microorganisms, which play a crucial role in breaking down organic matter during the treatment process. High levels of dissolved oxygen typically suggest a healthy and active biological system, as these microorganisms require oxygen for respiration and metabolic processes. In contrast, temperature is important for influencing biological activity but does not directly measure it. pH levels are essential for optimal microbial function and can affect various biochemical processes, but they do not provide a direct indication of the level of biological activity. Turbidity relates more to the clarity of water, influenced by suspended particles, rather than the metabolic state of the organisms present. Thus, dissolved oxygen content stands out as the most direct measure of biological activity within a treatment facility.