Tennessee Wastewater Operator Practice Exam

Which nitrogen compound is typically not found in influent wastewater?

1. Amonnia

2. Nitrate

3. Nitrite

4. Urea

The correct answer is: Nitrite

The nitrogen compound that is typically not found in influent wastewater is nitrite. In the context of wastewater treatment, influent refers to the wastewater entering a treatment facility, which consists mainly of raw sewage containing various nitrogen sources. Ammonia and urea are commonly found in influent wastewater as they are products of organic matter decomposition and human waste. Nitrate is generally a product of the nitrification process that occurs within treatment systems, where ammonia is converted first to nitrite and then to nitrate by nitrifying bacteria. However, nitrite does not generally appear in significant amounts in the influent, as it is a transient intermediate stage of the nitrification process. It quickly gets oxidized to nitrate before wastewater leaves the treatment plant. This context highlights that nitrite is not typically present in influent, as it is more frequently observed during the treatment process rather than in the raw influent itself.