Florida Wastewater Practice Test

What is a common consequence of low dissolved oxygen in treatment systems?

1. Improved effluent quality

2. Increased algae growth

3. Inhibited bacterial activity

4. Rapid sedimentation

The correct answer is: Inhibited bacterial activity

In wastewater treatment systems, low dissolved oxygen levels can significantly impact the biological processes that are essential for treating wastewater. Bacteria play a crucial role in breaking down organic matter and nutrients in the treatment process, and these microorganisms require a sufficient amount of dissolved oxygen to thrive and function effectively. When dissolved oxygen levels are low, it inhibits the activity of aerobic bacteria, which are responsible for the oxidation of organic matter. This inhibition can lead to reduced treatment efficiency, as less organic material is broken down, ultimately compromising the overall quality of the effluent. The other consequences, while they may seem relevant, are not directly tied to the primary function of dissolved oxygen in the treatment process. Improved effluent quality would not occur due to low oxygen levels, as this typically results in poorer treatment outcomes. Increased algae growth is more commonly associated with high nutrient levels and excess sunlight rather than low dissolved oxygen. Rapid sedimentation relates to physical processes in sedimentation tanks and is not primarily influenced by oxygen levels in the same direct manner as bacterial activity. Thus, the focus on inhibited bacterial activity as a consequence of low dissolved oxygen levels provides a clear understanding of the importance of maintaining appropriate oxygen levels in wastewater treatment systems.