Coagulation - Flocculation

1. Description: Drinking or waste water, in varying amounts, contains suspended material, solids that may settle at rest or dispersed solids that do not settle with ease. A considerable part of these solids that do not settle can be colloids. In colloids, each particle is stabilized by a series of charges of the same sign on its surface, making the two nearby particles repel each other as two magnetic poles do. Since this prevents particles from crashing into each other and thus forming larger particles, called flocs, these particles do not settle.

Coagulation and flocculation operations destabilize colloids and cause them to settle. This is usually accomplished with the addition of chemical agents and applying the mixture energy. The terms coagulation and flocculation are both used interchangeably with the formation of aggregates. However, the conceptual differences between these two operations should be noted. Confusion comes from the fact that both operations often occur simultaneously. To clarify ideas, we will define coagulation as the destabilization of colloidal suspension, while flocculation is limited to the transport phenomena of coagulated particles to cause collisions among them, promoting their agglomeration. Therefore: Coagulation is a colloid destabilization caused by the elimination of double electrical layers surrounding all colloidal particles with formation of microscopic nuclei; meanwhile flocculation consist on destabilized particle agglomeration, first in micro floccules and later in large clumps called flocs.

2. Design ranges: please consult our Engineering Department.

Important factors to consider in the design:

     a. pH influence.

     b. Influence of dissolved salts.

     c. Water temperature influence.

     d. Coagulant dosage influence.

     e. Mixture influence.

     f. Turbidity influence.

     g. Flow treatment.

     h. Chemical dosing.

3. Applications: Industrial plants (metallurgical, chemical, petrochemical, pharmaceutical, etc.).

4. Benefits:

     a. Low cost of operation and maintenance.

     b. Neutralization of contaminants.