What is the purpose of grit removal?

• A. To remove organic solids
• B. To reduce odors
• C. To remove heavier inorganic particles (grit such as sand and gravel)
• D. To remove suspended solids via clarification

Answer: (C)

Grit removal focuses on pulling out heavy inorganic particles that would cause wear and blockages in the treatment system. Grit such as sand, gravel, and cinders is much denser than organic matter, so when flow is slowed in a grit chamber these particles settle out and are removed. This protects pumps, pipes, and downstream equipment from abrasion and accumulation.

Organic solids, by contrast, are lighter and typically require clarification or primary treatment to be removed, not grit removal. Odors come from decomposing organics further along in the process, not from grit. Clarification units remove suspended solids in a different step, whereas grit removal specifically targets the heavier inorganic particles.