Flotation is a physical separation process used to remove suspended solids, oils, greases, algae and other low-density contaminants from water. Fine gas bubbles attach to particles, causing them to rise to the surface where they are removed as a floating sludge layer.
Flotation is one of the most widely used particle-removal processes globally and sits alongside sedimentation, filtration, membrane filtration, activated carbon, ion exchange and coagulation and flocculation.
Common flotation technologies
- DAF (Dissolved Air Flotation). Air is dissolved under pressure and released as microbubbles.
- IAF (Induced Air Flotation). Mechanically generated bubbles are introduced into the water stream.
- Electroflotation. Gas bubbles are generated electrolytically at electrodes.
Typical applications
- Municipal wastewater treatment
- Industrial wastewater treatment
- Food and beverage processing
- Aquaculture and RAS systems
- Algae harvesting
- Oil and grease removal
Advantages
- Efficient removal of fine suspended particles
- Effective oil and grease separation
- Lower footprint than many sedimentation systems
- Can improve downstream filtration performance
Limitations
- Requires energy and mechanical equipment
- Often benefits from coagulants or flocculants
- Generates sludge requiring handling and disposal
- Performance depends on particle characteristics and bubble generation
See also filtration, activated carbon, ion exchange, reverse osmosis and PFAS removal.