The dissolved air flotation is a technology that can be used for the removal of suspended solids, oil and grease or the thickening of sludge.
Flotation systems the dissolved air (DAF) are based on solids or the oily particles separation via its drag by air microbubbles (20 to 50 microns). A fraction of the clarified liquid is recirculated into a pressurized vessel (saturation vessel) within which there is the solubility of the compressed air (typically subjected to pressures of the order of 4 to 5 atm) in the liquid phase.
This mixture goes to the flotation chamber, subjected to a much lower pressure (atmospheric pressure). The air that was dissolved in the pressurized stream is eliminated into the atmosphere in the form of microbubbles, which adhere to solid and / or oil particles in the water or effluent and follow an upward trajectory.
The sludge is removed from the top of the flotation chamber through a scraper surface, while the clarified will be withdrawn beneath the bed of sludge.
For some applications, dissolved air flotation technology has important advantages compared to sedimentation:
- The hydraulic application and solids rates and solids are much larger, making it more compact flotation chambers and shallower than the clarifiers;
- The good separation of solids is independent of sludge facility in compact form flakes, which is a key differentiator for biological wastewater treatment systems;
- The concentrations of the separated solids are larger (3 to 5% dry solids), eliminating the sludge thickening stage;
- Efficient for water with emulsified oils and fats, raw water with low turbidity and high color and water reservoirs with algae blooms; flotation is the technique that allows the best quality of treated water.
UPE has several references in dissolved air flotation systems for the treatment of water and wastewater, designing and manufacturing rectangular and circular systems for clients in different segments.