Tennessee Wastewater Operator Practice Exam

What does denitrification convert nitrite and nitrate into?

1. Ammonia

2. Nitrogen gas

3. Carbon dioxide

4. Oxygen

The correct answer is: Nitrogen gas

Denitrification is a crucial biological process in the nitrogen cycle where denitrifying bacteria convert nitrite (NO2-) and nitrate (NO3-) into nitrogen gas (N2). This process occurs under anaerobic conditions, meaning it takes place in environments devoid of oxygen, such as in sediment or during certain stages of wastewater treatment. The primary outcome of denitrification is the release of nitrogen gas into the atmosphere, which is essential because it helps reduce the concentration of nitrogen compounds in water environments, thus preventing issues like eutrophication. Nitrogen gas is a stable, inert gas that constitutes a significant portion of the Earth's atmosphere. The other possible answers represent different processes or compounds that do not accurately describe the end products of denitrification. Ammonia is produced in different stages of the nitrogen cycle, but it is not a direct product of denitrification. Meanwhile, carbon dioxide is released during processes like respiration and aerobic decomposition, not denitrification. Oxygen is a byproduct of photosynthesis and does not play a role in the denitrification process. By understanding this process and its significance in water treatment, operators can better manage nitrogen levels in wastewater to ensure environmental safety and compliance with regulations.