Floculant Preparators

PREPARATION OF ORGANIC POLYMERS

A deeply knowledge of the properties and characteristics of the organic polymers used in water treatment is important for the optimal use of these reagents.

The Polymer preparators are units for automatic preparation of organic polymers of flocculants.
This flocculant is to be put into the Decanters to make the detachment of solid-Liquid process going forward.
The construction can be done in stainless steel, in polyethylene (PE) or polypropylene (PP).

Characteristics:
Organic flocculants are:
• High molecular weight which  can range from 3.000.000 to 20.000.000;
This allows the flocculant to agglomerate the already destabilized particles.
• An ionic charge that varies from 0 to 100 % anionicity (-) or cationicity (+), depending on the effluent to be treated.
• Various physical forms: liquid, powder, beads, emulsion, dispersion.

There are two categories of flocculant :
• Anionic flocculants that bring anionic charges (-) into the medium.
• Cationic flocculants that bring cationic charges (+) into the medium.

 
Several commercial forms exist and they come from different methods of polymerization :
• Powders: : The monomers are polymerized in a gel form. The gel obtained is then ground and dried. The main advantage of these products is the 100% active matter.
• Emulsions : The monomers are emulsified in a solvent and then polymerized. At the end of polymerization, a surfactant is added to make the emulsion dilutable in water. The main advantages of these products are their liquid form (easy to use) and an increased efficiency on certain applications (possibility of obtaining specific molecular structures).
• Liquids : Monomers are polymerized at low concentration in aqueous solution. The main advantage with these products is the simplicity of use.

Process Description:
Once they are in the aqueous solution, the flocculants have active groups: (+) charges or (-) charges. Depending on whether the flocculant is more or less ionic, the interaction with the particles is accomplished through ionic or hydrogen bonds.
The type and the percentage of electrical charge chosen for flocculation should be tested in the laboratory to insure good results with the types of particles present in the water: mineral or organic. With their very high molecular weight, the flocculants allow the size of the already destabilized particles (coagulated or natural) to be increased and thus to accelerate the liquid/solid separation.

Use and dosage:
The flocculants must be completely dissolved before use. This dissolution depends on the commercial form :
• For products in solid form: after good dispersion of each grain separately in the water, agitation for one hour is necessary for getting maturation. The agitation should be sufficient to maintain the product in suspension, but not too fast thereby avoiding the mechanical degradation of the polymer. After maturation, a uniform, viscous solution is obtained.
• For emulsions : aggressive agitation is necessary when the emulsion comes into contact with the water. Maturation is quicker and the solution can be used immediately.
• For liquids : an in-line dilution with a static mixer is sufficient.

We recommend active material concentrations of 1 g/l for the anionic flocculants and 3 g/l for the cationic flocculants.

Industrial preparation
Industrial use depends mainly on the commercial form of the polymers.


LIQUIDS:
The liquid products such as the organic coagulants and the flocculants resulting from a reaction require relatively simple equipment. They can easily be pumped and diluted either by in-line dilution with a static mixer, or in an agitated tank.

EMULSIONS:
For the flocculants in emulsion form, simple dilution in water is impossible. Indeed, two phenomena occur during the preparation of a polymer solution obtained from an emulsion:
• An inversion phase: the flocculant passes from the continuous oil phase to a continuous water phase.
• A dissolution phase: fast.

The quality of the inversion/dissolution depends on the following rules :
• The emulsion must be added to water and not the reverse.
• High cut should be applied when the emulsion comes into contact with the water. This prevents the formation of lumps.

POWDERS:
Solid flocculants require specific equipment for their dissolution with at least one flocculant dispersing device and an agitated tank. In addition, it is important to take into account the maturation time. That is why there are usually at least 2 tanks, one for dissolution and the other for feeding the solution.

CONIEX has develop the series Polymaker for continuous systems of preparing the polymer in powder, totally automatic, up to 5.000 lt./h in concentrations of 1 to 5 g/lt., that allows obtaining a final product of high quality.
The systems Polymaker already include a big number of accessories and automatisms, to monitoring all the process.

LIST OF THE AVAILABLE MODELS:

Coniex