What is the primary purpose of a grit chamber in a municipal wastewater treatment plant?

• A. To aerate wastewater.
• B. To remove grit before biological treatment.
• C. To settle solids after treatment.
• D. To remove advanced pollutants.

Answer: (B)

Grit removal is about protecting downstream treatment and equipment by letting heavy inorganic particles settle out early. Grit—things like sand, gravel, and small stones—can cause abrasive wear on pumps, pipes, screens, and clarifiers, and can accumulate in basins if not removed. A grit chamber slows the flow just enough that these heavier particles settle by gravity, while lighter organic matter stays in suspension. This happens before biological treatment, so the equipment that follows isn’t damaged or clogged and the treatment processes work more effectively. It’s not about aerating the water, settling solids after treatment, or removing advanced pollutants, which require other steps. Therefore, removing grit before biological treatment is the primary purpose.