Tennessee Wastewater Operator Practice Exam

What characteristic defines high speed surface aerators?

1. Impeller is externally driven

2. Impeller direct coupled to the motor

3. Multi-stage pumping capability

4. Use of compressed air systems

The correct answer is: Impeller direct coupled to the motor

High speed surface aerators are characterized primarily by having their impellers directly coupled to the motor, allowing for efficient transfer of energy into the wastewater for aeration. This direct coupling is crucial because it minimizes mechanical losses and improves the overall efficiency of the aeration process. The configuration ensures that the aerator can deliver a high level of oxygen transfer, which is essential for the effective treatment of wastewater. In contrast, other characteristics mentioned do not specifically define high speed surface aerators. While external driving of the impeller could apply to certain designs, direct coupling tends to be the more efficient and common method for these types of aerators. Multi-stage pumping capability is generally associated with other types of pumps rather than surface aerators, as they work well for different operational requirements. The use of compressed air systems typically pertains to diffused aeration systems, which operate differently from high speed surface aerators. Understanding these distinctions helps clarify the specific function and design of high speed surface aerators in wastewater treatment processes.