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Dissolved Air Flotation Tank (DAF)

Dissolved Air Floatation System
  • DAF is the process of removing suspended solids, oils and other contaminates via the use of air bubbles flotation. Air is dissolved into water, mixed with the wastewater stream and released from solution while in intimate contact with the contaminants. Air bubbles form, attach to the solids, increase their buoyancy and float the solids to the water’s surface where they are mechanically skimmed and removed from the tank.

  • A percentage of the clean effluent wastewater is recycled into the saturation vessel, where it is mixed together with air. In the saturation vessel the mixture of air and recycled effluent is pressurized and after reaching a certain level, it is injected into the DAF separation chamber. Hereby, the dissolved air comes out of solution in the form of very fine bubbles that attach to the contaminants. The bubbles and the contaminants rise to the surface and form a floating bed of material that is removed by a surface skimmer into an internal hopper for further handling. This handling may include a belt filter press or a rotary vacuum drum with DE applied.

  • Dissolved air flotation systems are designed to remove fats, oils and grease (FOG), suspended solids (TSS), biological oxygen demand (BOD), chemical oxygen demand (COD), food/animal production/processing wastes, industrial wastes, hydrocarbon oils/emulsions and many other contaminants. Clarification rates as high as 97 % or more can be achieved using DAF systems combined with the right allocation of chemicals. The DAF system is manufactured fully in stainless steel materials, to ensure a long lasting performance.

Typical Removal Rate by Watterson DAF :

  • The DAF unit is an open tank separator for dissolved air assisted separation of particles from water.

  • Figure 1 illustrates the different chamber within the DAF System and how those chambers are interconnected.

Dissolved Air Floatation System
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