Tennessee Wastewater Operator Practice Exam

What problems do septic conditions in the collection system cause at the treatment plant?

1. Excessive nutrients

2. Odor and oxygen demand

3. Decreased flow rates

4. Increased temperature

The correct answer is: Odor and oxygen demand

Septic conditions in the collection system primarily lead to odor and elevated oxygen demand at the treatment plant. When wastewater becomes septic, it indicates an anaerobic environment where organic matter is decomposed by bacteria that don't require oxygen. This process generates foul odors due to the production of gases like hydrogen sulfide and methane. Additionally, septic conditions increase the biochemical oxygen demand (BOD) of the wastewater, which is the amount of oxygen that microorganisms will consume while decomposing organic matter. A higher BOD means that more oxygen is required to treat the wastewater effectively, potentially leading to challenges in maintaining sufficient levels of dissolved oxygen in the treatment process. This can affect the performance of aerobic treatment processes, resulting in inefficient treatment and further odor problems. The other options relate to different issues that may not be the primary concern stemming from septic conditions. Excessive nutrients can occur from various sources but are not directly linked to septic conditions. Decreased flow rates tend to relate more to blockages or sedimentation in the collection system rather than septic conditions. Increased temperature is not a direct consequence of septic conditions but can be influenced by various environmental factors.