Tennessee Wastewater Operator Practice Exam

In wastewater treatment, what is the main purpose of a settling pond?

1. To increase dissolved oxygen levels

2. To reduce TSS levels

3. To sterilize the water

4. To enhance nutrient absorption

The correct answer is: To reduce TSS levels

The main purpose of a settling pond in wastewater treatment is to reduce Total Suspended Solids (TSS) levels. Settling ponds are designed to allow solid particles suspended in the wastewater to settle out of the liquid phase due to gravitational forces. This process occurs as the flow velocity decreases within the pond, enabling heavier solids to settle down to the bottom and form sludge. Effective removal of suspended solids is crucial, as high TSS levels can lead to various issues, including water quality degradation in receiving waters and reduced efficiency in subsequent treatment processes. By promoting the settling of solids, these ponds play an essential role in the primary treatment of wastewater, making it less turbid and preparing it for further treatment steps. The other options, while related to aspects of water treatment, do not accurately summarize the primary function of a settling pond. For instance, increasing dissolved oxygen levels occurs in aeration processes and is not the focus of settling ponds. Sterilization of water is generally achieved through disinfection processes, and nutrient absorption might take place in different biological treatment systems but is not a primary function of settling ponds.