What is the purpose of grit removal in preliminary treatment?

• A. Removes dissolved solids
• B. Sedimentation removes grit
• C. Kills pathogens
• D. Removes odors

Answer: (B)

Grit removal focuses on getting rid of heavy inorganic particles that can cause problems later in the treatment process. In preliminary treatment, wastewater passes through a grit chamber where dense particles like sand, gravel, and grit settle to the bottom by gravity. By removing these particles early, you protect pumps, screens, and piping from abrasion and reduce deposits that could interfere with downstream treatment steps. This is why the correct idea is that grit is removed by sedimentation in a grit chamber.

Dissolved solids aren’t removed by this step because grit removal targets physical, settleable particles, not dissolved materials. Pathogens are addressed by disinfection later in the process, and odors are controlled by dedicated odor management steps, not grit removal.