The use of diffused air to accelerate the formation of oil and grease scum is called which process?

• A. Flotation
• B. Aeration
• C. Clarification
• D. Precipitation

Answer: (A)

Flotation. Introducing air bubbles into the wastewater creates a large number of tiny bubbles that attach to oil and grease droplets. Those bubbles provide buoyant force, lifting the oily droplets to the surface where they form a scum that can be skimmed off. This use of air to promote separation of immiscible oils from water is what defines flotation (often called air flotation). Aeration mainly adds oxygen for biological treatment, not targeted removal of oil. Clarification relies on gravity to settle solids, and precipitation uses chemical reactions to form insoluble solids.