Tennessee Wastewater Operator Practice Exam

Which statement accurately describes the purpose of mixer aerators in treatment systems?

1. They primarily remove heavy metals from wastewater

2. They increase the dissolved oxygen levels while mixing the wastewater

3. They add nutrients to aid in the biological treatment

4. They help in the precipitation of suspended particles

The correct answer is: They increase the dissolved oxygen levels while mixing the wastewater

Mixer aerators play a crucial role in wastewater treatment by both increasing the dissolved oxygen levels in the water and promoting the mixing of the wastewater. This process is vital because many biological treatment processes, such as activated sludge systems, rely on the presence of dissolved oxygen to facilitate the breakdown of organic matter by aerobic microorganisms. By efficiently mixing the wastewater, mixer aerators help distribute the oxygen throughout the treatment system, ensuring that all parts of the wastewater are adequately aerated. The importance of oxygen in these systems cannot be overstated, as it directly affects the efficiency of the microbial processes taking place. The enhanced mixing also helps prevent the settling of solids, promoting a more uniform treatment and optimizing the overall performance of the system. While other choices touch on aspects related to wastewater treatment, they do not accurately reflect the primary function of mixer aerators. Options discussing the removal of heavy metals or the addition of nutrients, for example, refer to different components and processes in wastewater treatment that are not directly associated with mixer aerators.