Tennessee Wastewater Operator Practice Exam

What should an operator check if an aerated grit basin shows a smooth surface and poor mixing today?

1. Flow rate

2. Diffuser for rags

3. Aeration level

4. Grit removal system

The correct answer is: Diffuser for rags

In the context of an aerated grit basin, a smooth surface combined with poor mixing typically signifies that the water is not being agitated properly, which can lead to sediments like grit not being adequately removed. This situation often indicates that the air diffusers, which are responsible for introducing air into the basin and thereby creating the mixing action necessary for proper grit removal, may be obstructed or malfunctioning. When the air diffusers are blocked or clogged with debris—such as rags or other materials—it can prevent air from rising through the water effectively, leading to a lack of adequate mixing and a flat water surface. This condition is a critical observation because the aerated grit basin relies on those diffusers to ensure that grit is suspended and flows toward the grit removal system. While checking the flow rate, aeration level, or the grit removal system may also be important in maintaining the overall operational efficiency of the treatment facility, in this particular scenario, the immediate focus should be on the diffusers since they directly influence the agitation and mixing required in the basin. Ensuring the diffusers are functioning correctly is crucial for maintaining the necessary conditions for effective grit separation and removal.