In a vortex-type grit chamber, how are solids separated from the wastewater?

• A. The water and grit rotate slowly around the vertical axis, allowing heavier solids to settle at the bottom.
• B. The flow is directed straight through a central pipe without rotation.
• C. Grit is removed by dissolving the solids in chemical treatment.
• D. The chamber relies on UV disinfection to separate grit.

Answer: (A)

In a vortex grit chamber, solids separation happens through the swirling motion around a vertical axis. The rotation creates a centrifugal effect that drives heavier grit toward the outer wall and down to the bottom, where it collects as settled solids. Lighter materials stay more in suspension and are carried toward the outlet, so the wastewater leaving the chamber has much less grit. That’s why the description of rotating water and grit with heavier solids settling at the bottom is the best fit. The other ideas don’t describe how grit is separated: a straight-through flow lacks rotation needed for settling, dissolving solids chemically isn’t grit separation, and UV disinfection isn’t a method for removing grit.