What is the typical shape of an aerated grit chamber?

• A. Circular.
• B. Rectangular.
• C. Cylindrical.
• D. Spherical.

Answer: (B)

Aerated grit chambers are built to let heavy grit settle out while keeping lighter organic matter in suspension, using air sparging to promote mixing and prevent settling of organics. To accomplish this, the basin is designed as a long, shallow channel so the flow has enough residence time for grit to settle, without the flow becoming turbulent or short-circuited.

A rectangular shape provides a uniform, wide flow path across the full width of the basin, making it easy to distribute air evenly and install grit collectors and baffles along the bottom. This setup ensures consistent settling across the basin and straightforward construction and maintenance.

Circular or cylindrical basins tend to encourage swirling flows and uneven aeration, complicating uniform grit removal. Spherical shapes are impractical for construction and flow control in grit handling.