Flokulaation

Flokulaation is a process in colloid chemistry and environmental engineering in which fine suspended particles aggregate into larger clumps called flocs. This growth in particle size facilitates the removal of contaminants by sedimentation, flotation, or filtration, and is a common step in water and wastewater treatment as well as in some industrial processes.

The process usually follows coagulation, where destabilized particles have their surface charges neutralized. During flokulaation, gentle mixing promotes frequent particle collisions and bonding, often aided by polymeric flocculants that bridge particles together. Key mechanisms include charge neutralization, bridging flocculation where long polymer chains connect particles, and sweep flocculation, in which newly formed precipitates physically enclose suspended matter.

Operational parameters include coagulant dose, polymer dosage, mixing intensity and duration, pH, temperature, and ionic strength of the water. Optimizing these factors often involves jar tests or similar pilot procedures. Commonly used substances are inorganic coagulants such as aluminum sulfate or ferric chloride, sometimes supplemented by lime, and organic flocculants like polyacrylamides or starch-based polymers. Natural polymers can also be employed in some cases.

Applications span drinking water treatment, municipal and industrial wastewater treatment, and process water in mining, pulp and paper, and food industries. Flokulaation also plays a role in soil stabilization and environmental remediation by aggregating fine particles to improve handling and transport.

Measurement and control tools include turbidity reduction monitoring, zeta potential assessment to gauge surface charge, and particle size distribution analyses. Operational challenges can include overflocculation, under-flocculation, residual coagulants, and energy costs associated with mixing.