Tennessee Wastewater Operator Practice Exam

What type of odor should an operator expect from an aerobic digester?

1. Harsh and chemical

2. Foul and rotten

3. Pleasant and musty

4. Neutral and unnoticeable

The correct answer is: Pleasant and musty

An aerobic digester typically emits a pleasant and musty odor, which is a result of the biological activity taking place within the digester. In aerobic digestion, microorganisms break down organic material in the presence of oxygen, leading to the stabilization of wastewater sludge. This microbial activity can produce odors that are often described as earthy or musty rather than harsh, foul, or chemical. The presence of oxygen supports the breakdown of organic compounds, resulting in fewer odors associated with anaerobic processes, which are commonly characterized by strong and unpleasant smells due to the production of hydrogen sulfide and other volatile organic compounds. Therefore, the musty odor from the aerobic digester is an indicator of the active biological processes that are beneficial for treating the wastewater, highlighting the effectiveness of aerobic treatment in managing odors compared to other methods.