Tennessee Wastewater Operator Practice Exam

What will typically cause a decrease in grit removal efficiency when using cyclones in a grit removal process?

1. High cyclone inlet pressure

2. Cyclone outlet blockage

3. Cyclone inlet pressure too low

4. Excessive grit concentration

The correct answer is: Cyclone inlet pressure too low

The effectiveness of a cyclone in a grit removal process is highly dependent on the configuration of fluid dynamics occurring within the cyclone. When the cyclone inlet pressure is too low, the flow velocity entering the cyclone decreases, which can lead to insufficient centrifugal force generated in the cyclone. This force is crucial for separating the grit particles from the lighter organic material and water. Inadequate inlet pressure means that grit particles do not experience the strong forces necessary to settle out of the suspension effectively. As a result, grit may bypass the collection zone intended for solid removal, thus reducing the overall efficiency of the grit removal process. Low inlet pressure can also cause turbulence within the cyclone, preventing the creation of a well-defined flow pattern that is essential for effective separation. A properly optimized inlet pressure is important to ensure that grit particles are effectively captured and removed before the effluent exits the cyclone.