DAF is used to remove which substances from wastewater?

• A. Dissolved Salts
• B. Suspended Solids
• C. Oil and Grease
• D. Nutrients

Answer: (C)

Dissolved Air Flotation targets materials that tend to float in wastewater. In this process, water is saturated with tiny air bubbles that attach to oil droplets and other light, floating particles. The bubbles reduce the overall density of these contaminants, lifting them to the surface where they form a skimmed layer that can be removed. This makes it especially effective for removing fats, oils, and greases, which are buoyant and often form emulsions that are hard to separate by settling or filtration alone. Dissolved salts remain dissolved and typically require other treatment methods like reverse osmosis or precipitation. Nutrients are usually removed by biological or chemical processes rather than flotation. So oil and grease is the best match for what DAF is designed to remove.