Flocculation
Introduction
Flocculation is a chemical process by which, with the addition of substances called flocculants, the colloidal substances present in the water are agglutinated, thus facilitating its decantation and subsequent filtering "Filter (hydraulics)"). It is a step in the process of purifying surface water and treating domestic, industrial and mining wastewater.
The compounds present in water can be:
Process
The flocculation process is preceded by coagulation, which is why we usually speak of coagulation-flocculation processes. These facilitate the removal of suspended substances and colloidal particles:
The factors that can promote coagulation-flocculation are the gradient of velocity, time and pH. Time and velocity gradient are important by increasing the probability that the particles come together and giving more time for the particles to descend, due to gravity, and thus accumulate at the bottom. On the other hand, pH is a prominent factor in the destabilizing action of coagulant and flocculant substances.
The most appropriate flocculating solution for the nature of the suspended materials in order to achieve clean settled waters and the formation of thick sludge is determined by tests, either in the laboratory or in the field.
In mining, the flocculants used are high molecular weight synthetic polymers, whose molecules are long chain and have great affinity for solid surfaces. These macromolecules are fixed to the particles by adsorption and thus cause flocculation by the formation of interparticle bridges.
Types of flocculation
Ionic flocculation
Through ionic flocculation, the molecules dissolved in a fluid are modified through the action of the so-called ionic flocculators, which are material elements composed of stainless steel, silver or copper tubes, which connected at their end to poles of direct current, positive or negative, generate ionic activity. Ionic flocculators immersed in the fluid produce a low intensity electric field with constant ionic activity, which increases the energy of the bonding electrons; then, the atoms that make up the molecules diluted in the medium undergo a change in their structure that takes them to their most elemental form, confirming the electrolytic theory of dissociation.