DAF is a treatment method that can be used for removal of which contaminant?

• A. Oil
• B. Color
• C. Bacteria
• D. Nutrients

Answer: (A)

Dissolved Air Flotation works by introducing tiny air bubbles that attach to floatable contaminants, causing them to rise to the surface so they can be skimmed off. This makes it especially effective for removing oil and grease, which form droplets that readily attach to the bubbles and float. In industrial wastewater, oily layers and emulsified oils are common targets for DAF because they are buoyant and can be separated quickly this way.

Color, bacteria, and nutrients aren’t the primary targets of DAF. Dissolved color often comes from dissolved compounds that require different treatment approaches, bacteria are typically removed by disinfection or filtration, and nutrients usually need biological processes or chemical precipitation.