Tennessee Wastewater Operator Practice Exam

What type of design is often used to enhance the settling of grit in a grit basin?

1. Sloped floors

2. Conical bottoms

3. Vortex design

4. Flat surfaces

The correct answer is: Vortex design

The vortex design is specifically intended to enhance the settling of grit in a grit basin by creating a circular flow that helps to keep larger particles suspended momentarily while allowing smaller, dense materials to settle more quickly. In a vortex system, the rotational movement of water enhances the segregation of grit from the rest of the wastewater. The centrifugal force generated pushes denser materials like grit towards the outer wall, where they can more easily settle and be collected. This design contrasts with methods that rely on gravity alone, such as sloped floors, conical bottoms, or flat surfaces, which may not effectively manage the flow dynamics necessary for optimal grit removal. Each of those traditional designs has its advantages but typically lacks the specific efficiency of a vortex design in terms of rapid grit settling and minimizing the potential for re-suspension of settled particles. Thus, the vortex design is particularly advantageous in wastewater treatment facilities that need to efficiently handle grit removal.