Tennessee Wastewater Operator Practice Exam

When should the air be turned on in an aerated grit chamber that is being returned to service?

1. Before the wastewater is introduced

2. When the wastewater reaches the diffusers

3. After the chamber is fully filled

4. Once the grit is settled

The correct answer is: When the wastewater reaches the diffusers

The aerated grit chamber is designed to facilitate the removal of grit from the wastewater before it undergoes further treatment processes. Turning on the air when the wastewater reaches the diffusers is essential because it ensures that the aeration process is initiated at the appropriate moment, allowing for effective mixing and the establishment of the desired flow conditions in the chamber. By activating the air supply only when the wastewater is present, the system can promote optimal contact between the wastewater and the air, enhancing the effectiveness of grit removal. This timing helps to prevent issues such as the settling of grit before sufficient aeration has occurred, which could lead to ineffective grit separation or the buildup of grit in the chamber. In contrast, turning on the air before the wastewater is introduced could lead to unnecessary turbulence and hinder the proper settling of grit. Activating the aeration after the chamber is completely filled could result in an inefficient aeration process and may not adequately prepare the chamber for optimal grit removal when wastewater is introduced. Finally, turning on the air only after grit has settled does not support the primary purpose of the aerated grit chamber, which is to keep the grit in suspension until it can be efficiently removed.