Dissolved Air Flotation (DAF)


Dissolved Air Flotation (DAF)

Dissolved air flotation (OAF) is a water treatment process that clarifies waste water (or other water) by the removal
of suspended matter such as oil or solids. This removal is achieved by dissolving air in the water or wastewater
under pressure and then releasing the air at atmospheric pressure in a flotation tank basin. The released air forms tiny bubbles which adhere to the suspended matter causing the suspended matter to float to the surface of the water where it may then be removed by a skimming device.

The OAF separator provides effective separation of suspended solids, fats, oils and greases from liquids by dissolved air flotation. Flotation of the solids is accomplished by the introduction of tiny air bubbles into the process water. As the bubbles rise, they attach themselves to the particles in suspension and carry them to the surface for removed.


Advantages of Using DAF over other Clarification Processes

  • OAF is more efficient in removing low-density floe than, sedimentation processes
  • The problem of algae clogging filters and reducing filter run times usually occurs in the plants. But OAF is effective in removing algae from water supplies. In fact, air bubbles formed in OAF can also remove some taste and odour compounds from the water which can be considered as a secondary benefit
  • OAF is more effective than sedimentation in removing pathogens such as Giardia cysts and Cryptosporidium oocysts
  • OAF plants have a lesser footprint compared to sedimentation plants on account of smaller tanks. In some cases, OAF is placed over filtration reducing the plant footprint further
  • OAF produces floating sludge with higher percent of solids which possibly reduces biological sludge treatment and disposal
  • Energy savings is higher in OAF compared to sedimentation plants as smaller motors are used to run the flocculator, longer filter runs, and less filter back washing of filters
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