Wastewater Treatment Operator Certification Practice Test

What is true about surface loading and detention time?

1. They stay fairly constant throughout the day

2. They are impacted by the influent BOD

3. They are indirectly related to flow

4. They are directly related to flow

The correct answer is: They are directly related to flow

Surface loading and detention time are both directly affected by the flow entering a treatment system. When flow increases, surface loading, which is the amount of wastewater applied to a treatment surface area per unit time, also increases. This means that more wastewater is being treated in the same area over a period of time. Similarly, as flow increases, the detention time, which refers to the amount of time wastewater remains in a treatment tank, typically decreases because the same volume of water must now be processed at a faster rate. Therefore, there is a direct relationship between flow and these two parameters, reflecting how the efficiency and effectiveness of wastewater treatment can be influenced by variations in influent flow rates. The understanding of this concept is critical for operators when designing and managing treatment systems to ensure optimal performance.