Optimal Polymer Mixing - Mixers & Polymer Make-Up Systems

Optimal Polymer Mixing in water and wastewater treatment processes is based on the best and efficient water to remove solid particles and other materials found in the wastewater stream.  A popular method in modern waster treatment system to eliminate contaminants is through the use of polymers in a sludge-creating process by using polymers to coagulate suspended solids and produce flocs which can be easily removed.

Types Of Polymers

Polymers are available in a variety of forms and supplied as either dry powders or liquids with each variation presents challenges when sizing mixers for the polymer vessels.

Dry Polymers:

• Polymers supplied in powder form must be blended in a mixing tank and often “aged” in a conditioning tank.

Liquid Polymers:

• Emulsion Polymer – An emulsion product allows the manufacturer to provide concentrated liquid polymer formulations that are not in a water-soluble form.  Emulsion polymers must be diluted before use and are generally done in a polymer feed system.
• Solution Polymer – Polymers supplied in this form are easier to dilute, handle and feed than the emulsion and dry polymers and generally be used without pre-use mixing.

Optimal Polymer Mixer Design

Polymers need to be mixed during the activation stage but with care, as the polymer is shear sensitive and the mixer needs to be low-speed, low-shear design to minimise the damaging the polymer.

Low Shear Polymer Mixers:

• Low Output Speed;  Portable mixers are generally sized to output speeds of 90-100 RPMs as standard for avoiding damage to the polymer.
• Impeller Design: Impeller is designed to minimize shear behind the impeller blade to promote good mixing/pumping within the vessel while keeping the shear level to a minimum.