Tennessee Wastewater Operator Practice Exam

What is the purpose of flow proportional weirs in velocity control horizontal flow grit basins?

1. Help in sedimentation

2. Maintain a constant velocity

3. Allow for larger particle removal

4. Control chemical dosing

The correct answer is: Maintain a constant velocity

Flow proportional weirs are specifically designed to maintain a constant velocity in flow control systems, such as those found in velocity control horizontal flow grit basins. These weirs adjust to changes in inflow rates, ensuring that the velocity of the water passing through the grit basin remains consistent. This is crucial because maintaining a constant velocity helps in the effective separation of grit and sediment from the wastewater, allowing for optimal performance of the grit removal system. A stable velocity prevents the resuspension of settled sediment and ensures that heavier particles are effectively removed, thus enhancing the overall efficiency of the treatment process. The function of these weirs directly supports the operational goals of the basin, making them critical in wastewater treatment.