DAF Units Explained: How Dissolved Air Flotation Removes FOG and TSS
Dissolved Air Flotation (DAF) is a physical-chemical process used to remove suspended solids, fats, oils and grease from wastewater before biological treatment. For high-strength industrial effluent, a DAF unit is often the difference between a stable plant and one that constantly struggles.
How dissolved air flotation works
Water is saturated with air under pressure and then released into the flotation tank, where it forms microscopic bubbles. The bubbles attach to suspended particles and float them to the surface, where a skimmer removes the float layer. Coagulant and flocculant dosing upstream makes fine particles clump together so they capture more easily.
What a DAF unit removes
- Fats, oils and grease (FOG)
- Total suspended solids (TSS)
- A portion of the organic load (COD/BOD bound to solids)
Where DAF fits
DAF is widely used in food and beverage plants, dairies, slaughterhouses and oily process streams. It usually sits as pretreatment ahead of a biological stage such as MBBR or MBR, protecting that stage and improving overall reliability. See how it fits into a complete industrial wastewater treatment system.
Have a greasy or high-solids stream? Send us your water analysis and we will advise on DAF sizing and chemistry. See our DAF units or contact our engineers.