Tennessee Wastewater Operator Practice Exam

Which type of bacteria is primarily responsible for the removal of ammonia in wastewater treatment?

1. Heterotrophic bacteria

2. Nitrifying bacteria

3. Denitrifying bacteria

4. Pathogenic bacteria

The correct answer is: Nitrifying bacteria

Nitrifying bacteria are crucial in the biological treatment of wastewater, specifically for the conversion of ammonia into nitrites and then into nitrates, a process known as nitrification. This is particularly important in wastewater treatment systems as ammonia can be toxic to aquatic life and should be reduced to safe levels before the treated water is discharged into water bodies. Nitrifying bacteria are aerobic organisms, meaning they require oxygen to function effectively. This group primarily includes two types of bacteria: ammonia-oxidizing bacteria (AOB) that convert ammonia to nitrite and nitrite-oxidizing bacteria (NOB) that further oxidize nitrite to nitrate. The activity of these bacteria is vital to ensuring that ammonia is transformed into less harmful compounds, thereby enhancing water quality and facilitating compliance with environmental discharge standards. Other types of bacteria mentioned in the options play different roles within the wastewater treatment process. Heterotrophic bacteria primarily break down organic matter, while denitrifying bacteria are responsible for the conversion of nitrates back into nitrogen gas, a process called denitrification, which helps to remove excess nitrogen from the water but does not directly target ammonia removal. Pathogenic bacteria, on the other hand, are associated with disease and are not involved in the wastewater treatment