Coagulante

Coagulante, or coagulant, is a substance that promotes coagulation, the process of destabilizing and aggregating dispersed particles in liquids so they can be removed. In water and wastewater treatment, coagulants neutralize the electrical charges on colloids, reducing repulsion and enabling floc formation. The resulting flocs settle in clarifiers or are captured by filters.

Common inorganic coagulants include aluminum salts (such as alum) and iron salts (ferric chloride, ferric sulfate); polyaluminum chlorides are also used. Organic coagulants comprise synthetic polymers, including cationic polyacrylamides and polyamines, which bridge particles to form larger aggregates. Natural or plant-based coagulants, such as extracts from Moringa seeds or tannin-rich materials, are studied as low-toxicity alternatives.

Coagulants act mainly by charge neutralization and, in some cases, polymer bridging, depending on dose, pH, and water chemistry. Dosage and mixing conditions are optimized to maximize floc growth while minimizing sludge production and residuals in the treated water. Typical processes involve rapid mixing to disperse the coagulant, followed by slower mixing to form flocs, then sedimentation or filtration for removal.

Applications include municipal drinking water treatment, wastewater treatment, and industrial process water in sectors such as paper, textiles, and mining. Advantages include effective removal of turbidity and color; disadvantages include sludge handling, chemical costs, and potential residuals that require management. Environmental and health regulations govern coagulant use and residual limits, guiding safer and more sustainable practices.