Tennessee Wastewater Operator Practice Exam

At what rotation rate do most hydraulically driven rotary distributors on trickling filters typically operate?

1. 0.5 RPM

2. 1 RPM

3. 2 RPM

4. 3 RPM

The correct answer is: 1 RPM

Most hydraulically driven rotary distributors on trickling filters typically operate at a rotation rate of 1 RPM. This rotation speed is ideal for evenly distributing the wastewater over the filter media, which is crucial for maximizing treatment efficiency. At this rate, the distributors provide enough time for the flow of water to meet the media surface, allowing for optimal contact time between the wastewater and the biological films on the media. If the rotation speed were significantly lower, such as 0.5 RPM, it may lead to excessive pooling and inadequate distribution across the filter, reducing treatment effectiveness. Conversely, a higher speed like 2 RPM or 3 RPM could result in insufficient contact time, potentially causing the wastewater to flow off too quickly and not allowing sufficient treatment. Therefore, a rotation of 1 RPM strikes a balanced approach, ensuring even dispersion and effective biological treatment on trickling filters.