Tennessee Wastewater Operator Practice Exam

Which of the following is NOT a type of nitrogen removal system?

1. Sand filtration

2. Nitrogen stripping

3. Denitrification

4. Ammonia reduction

The correct answer is: Sand filtration

Sand filtration is considered a physical process primarily aimed at removing suspended solids and some pathogens from wastewater. While it can help reduce turbidity and provide some level of treatment, it is not specifically designed for nitrogen removal. The primary types of nitrogen removal systems focus on biochemical or chemical processes that directly address nitrogen forms, such as ammonium and nitrate. Nitrogen stripping, denitrification, and ammonia reduction are all processes that specifically target nitrogen compounds. Nitrogen stripping involves the volatilization of ammonia from the wastewater, transforming it into the atmosphere. Denitrification is a biological process where nitrates are converted into nitrogen gas, thus removing nitrogen from the water. Ammonia reduction focuses on converting ammonia to less harmful substances through various biological or chemical methods. Understanding that sand filtration does not effectively target nitrogen compounds helps clarify why it does not belong to the group of nitrogen removal systems.