Tennessee Wastewater Operator Practice Exam

What condition must be met for denitrification to take place?

1. Presence of high oxygen levels

2. DO no longer available

3. High ammonia concentrations

4. Temperature must be low

The correct answer is: DO no longer available

Denitrification is a biological process in which nitrate is reduced to nitrogen gas or other nitrogenous compounds, effectively removing nitrogen from the ecosystem. This process is primarily carried out by certain bacteria under anaerobic conditions, which means that oxygen is not present. For denitrification to occur, the availability of dissolved oxygen (DO) must be minimal or absent. When oxygen levels are high, denitrifying bacteria typically use oxygen for respiration instead of nitrates. Therefore, the lack of dissolved oxygen creates an environment conducive to denitrification, allowing these specialized bacteria to utilize nitrates as an alternative electron acceptor during their metabolic processes. In environments where oxygen is scarce, such as in certain layers of wastewater treatment systems or in sediment-rich areas, denitrification can thrive, leading to a reduction of harmful nitrates in the water. Understanding this critical requirement highlights the importance of oxygen levels in the context of wastewater treatment and nutrient management.