Tennessee Wastewater Operator Practice Exam

Where does nitrogen gas end up after being produced during denitrification?

1. In wastewater treatment tanks

2. In the atmosphere

3. In soil layers

4. In the biomass

The correct answer is: In the atmosphere

During the denitrification process, nitrogen gas (N2) is produced as nitrates and nitrites are converted to gaseous forms of nitrogen by microorganisms in anaerobic conditions. This process effectively reduces the amount of nitrogen in wastewater, which is essential for controlling pollution and preventing eutrophication in aquatic ecosystems. The nitrogen gas generated during denitrification is released into the atmosphere, making it the correct conclusion of where nitrogen gas ultimately ends up. This gaseous nitrogen is a major component of the Earth's atmosphere, where it makes up approximately 78% of the air we breathe. In contrast, wastewater treatment tanks are where the biological processes take place, but they do not serve as the end destination for the nitrogen gas produced. Soil layers may retain some nitrogen in different forms, but not as N2 gas produced in denitrification. Similarly, biomass refers to the living organisms in the treatment system, which utilize nitrogen in different forms for growth but do not hold onto it as nitrogen gas. Thus, the primary fate of the nitrogen produced during denitrification is its release into the atmosphere.