Which grit removal type uses air injection to create spiral flow?

• A. Horizontal flow
• B. Vortex
• C. Bar screen
• D. Aerated

Answer: (D)

The key idea is using air to create a spiral flow that drives grit toward a collection point. In an aerated grit chamber, air is bubbled into the flow, and the rising bubbles generate a corkscrew motion through the water. This spiral movement helps keep organic material in suspension while heavier inorganic grit is carried along to the grit hopper or outlet. This aeration-created swirl is what sets this type apart from others. Horizontal flow grit chambers rely on straight, non-spiraling flow; vortex chambers achieve swirl through geometry and flow dynamics without deliberate air injection; bar screens remove large solids before grit treatment, not by creating a spiral flow.