Which step in the regeneration process uses water to float carbon fines created by the heat treatment?

• A. Washing
• B. Defining
• C. Rinsing
• D. Clarifying

Answer: (B)

The step tested here is flotation-driven separation of fines. After heat-treating activated carbon, tiny carbon fines are produced. To remove these fines without losing too much solid material, the process uses water to lift the fines to the surface so they can be skimmed off or separated. This flotation-based removal is the step described as “defining,” since it focuses on defining and removing the fines from the regenerated carbon by buoyancy in water. Washing or rinsing mainly cleans surfaces, and clarifying is about separating solids and liquids by settling, not specifically removing fines by flotation.