Flocculation and polymer dosing


After forming small flocs in the coagulation step (see coagulation), flocculant is dosed in order to create bigger and more stable flocs. The flocculant is often called polymer or poly-electrolyte.
Flocculant / poly-electrolyte must be prepared from a powder polymer or a fluid concentrated polymer.
Polymer is a product that must be well mixed with water to prevent clot formation. After mixing with water a certain maturation time is necessary to "unfold" the polymer chain.
Flocculant needs to "mature"  (30 to 45 minutes) before it can be dosed.
Matured polymer is a sticky liquid.
In smaller plants the production is matured in a "manual polymer mixing unit".  Usually the powder or liquid is mixed in a reaction tank 1 x per day.
For larger installations we strongly recommend automatic polymer make up stations for both powder and liquid polymer applications.
An automatic polymer make-up station consists mostly of three compartments with a dosing screw and a powder storage.

  • In the first compartment (A) the powder is mixed with water. The ratio water/powder can be set-up perfectly.
  • The second compartment (B) is a maturation tank with stirrer (11).
  • From the third compartment (C) the matured polymer is pumped into the flocculator. A level probe (2) mounted in an acrylic holder (3) controls (1) the make-up station.

The dosing screw (8) at the bottom of the powder storage (9) is provided with a heating element (10) to prevent condensation.
In a polymer make up station of liquid polymer, the entire powderbuffer and dosing screw is replaced by a polymer dosing pump

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