Tennessee Wastewater Operator Practice Exam

What percentage of total suspended solids (TSS) do primary clarifiers typically remove?

1. 10-30%

2. 50-70%

3. 30-50%

4. 70-90%

The correct answer is: 50-70%

Primary clarifiers are key components in wastewater treatment systems designed to remove solids from the wastewater before it undergoes further treatment. They function via gravity separation, allowing heavier solids to settle at the bottom while lighter materials, such as oils and greases, float to the surface. The correct answer, which indicates that primary clarifiers typically remove 50-70% of total suspended solids (TSS), reflects the efficiency of these systems in reducing the concentration of solids in the wastewater. This range is substantiated by the operational characteristics of primary clarifiers, which can effectively manage a significant portion of the suspended solids present in the influent. This removal percentage is critical as it directly impacts the overall effectiveness of the wastewater treatment process. By reducing the TSS load entering secondary treatment processes, primary clarifiers not only enhance the subsequent biological treatment outcomes but also help in decreasing the overall burden on the treatment system, leading to better operational performance and compliance with environmental regulations. In contrast, the other ranges presented do not accurately represent the capabilities of primary clarifiers. Removing less than 50% of TSS would indicate a less effective process, while suggesting a removal higher than 70% would imply that the primary clarifiers are functioning at a level that typically requires