In vertical shaft flocculator, impeller is attached to a vertical shaft. The shaft is rotated by an external gear reducer powered by an electric motor capable of running at various speeds using a variable frequency drive. The impellers are broadly classified as radial flow impeller and axial flow impellers, depending upon the flow pattern. Radial flow impeller directs flow outward from the impeller blades in horizontal direction. Axial flow impeller directs the flow parallel to the vertical shaft. Axial flow impellers can be upward pumping or downward pumping type.

The vertical shaft flocculators with axial flow impeller are generally used for flocculation process in water treatment. They can be classified based on the design of the blade:

• Hydrofoil Flocculator: The impeller has three or four blades with variable angle of contact. Hydrofoil blades generate high flow and create least shear when compared to other design of blade.
  
  
• Pitched Blade Turbine flocculator: In this type of flocculator, the blades of impeller have constant angle of attack. The most common is impeller with 3 or 4 blades pitched at 32o. When higher mixing intensity is required and higher fluid shear is acceptable, impeller with 4 blades pitched at 45o is also used.
  The standard material of construction of all type of vertical shaft flocculator is stainless steel.
  
  

.: Belize City, , Belize, Flocculators

.: Lagos, , Nigeria, Flocculator