Tennessee Wastewater Operator Practice Exam

What gas is mainly produced by bacteria in any type of pond system?

1. Methane

2. Oxygen

3. Nitrogen

4. Carbon dioxide

The correct answer is: Carbon dioxide

In pond systems, bacteria play a crucial role in the breakdown of organic matter, a process known as anaerobic decomposition when oxygen is absent. This process primarily leads to the production of carbon dioxide. As bacteria decompose organic material, they generate energy and release carbon dioxide as a waste product. This gas becomes suspended in the water and is often measured to assess the level of biological activity within the pond. Carbon dioxide is essential for the growth of aquatic plants, which utilize it during photosynthesis to produce oxygen, but the primary gas produced by the bacterial degradation process in these systems is carbon dioxide. In contrast, while methane is a by-product of anaerobic decomposition in some conditions, especially in certain environments, it is not the main gas produced in typical pond systems. Similarly, oxygen is produced by photosynthetic organisms, not primarily by bacteria. Nitrogen can be released during the nitrogen cycle, but it is not a primary product of bacterial activity in a pond setting. Thus, carbon dioxide is the correct answer as the main gas generated by bacteria in pond systems.