Circular Dissolved Air Flotation (DAF)

Thickeners are used in water and wastewater applications to take solids from other liquid solids separation processes and thicken the solids prior to further dewatering and/or digestion. The drive is mounted on the walkway or bridge. The rotating portion of the drive turns a structural torque tube or shaft, which in turn rotates the solids removal mechanism.


  1. Can develop high torque in compact units.
  2. Torque tube is generally more economical than a torque cage in
    smaller units.
  3. Can be installed in concrete or steel tank configurations.
    Generally, most economical in tanks less than 50’ in diameter.
  4. Generally the most economical way to provide lifting of rake arms
    under severe torque loads.

5.Lifting device option allows for heavy sludge loading.


  1. Walkway or bridge must span the tank and support the weight and torque of the mechanism, the bridge will be more expensive than for a center pier supported unit.


Center Feed Dissolved Air Flotation (DAF)

Rectangular Dissolved Air Flotation (DAF)

Chain and Flight Detail



Rectangular Dissolved Air Flotation (DAF)


1.Typically ship fully shop assembled

2.Can build integral coagulation and flocculation chambers

3.Lower installed costs

4.Can fit in narrow space (i.e. between buildings)


1.Chain and flight system is more prone to fail / higher maintenance

2.Less capacity for floating solids removal



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