Tennessee Wastewater Operator Practice Exam

In aerobic ponds, the primary source for dissolved oxygen is derived from which process?

1. Photosynthesis

2. Natural aeration

3. Mechanical diffusion

4. Thermal stratification

The correct answer is: Photosynthesis

In aerobic ponds, the primary source for dissolved oxygen primarily comes from the process of photosynthesis. This process occurs when aquatic plants, algae, and microorganisms use sunlight to convert carbon dioxide and water into glucose and oxygen. The presence of sunlight in an aerobic pond allows these organisms to thrive, releasing oxygen as a byproduct. This oxygen becomes dissolved in the water and is essential for maintaining the aerobic conditions that support the microbial processes necessary for effective wastewater treatment. While natural aeration can contribute to oxygen levels through mechanical means like wind or wave action, it is not the primary source of dissolved oxygen in these environments. Mechanical diffusion, which involves the physical movement of air into water, contributes less significantly to the oxygen supply compared to biological processes like photosynthesis. Similarly, thermal stratification refers to temperature layers in the water body which can affect oxygen distribution but does not directly contribute to its generation. Thus, photosynthesis is the key mechanism for oxygen production in aerobic ponds, making it the correct answer.