Koagulaation

Koagulaation, or coagulation, is the process by which dispersed particles become a solid or gel, or a phase that settles from suspension. The term is used in several disciplines, most notably biology and chemical engineering. In both contexts, surface charges on particles are altered so that they can come together and form a network that traps additional material.

In physiology, coagulation refers to hemostasis, the body's response to vascular injury. Platelets adhere to exposed surfaces, aggregate, and provide a scaffold for the coagulation cascade. This cascade involves a series of clotting factors that activate thrombin, which converts fibrinogen into fibrin to form a stable mesh that reinforces the platelet plug. Calcium ions and vitamin K are essential cofactors. The process is tightly regulated by anticoagulant pathways to prevent excessive clotting. Defects in coagulation can cause bleeding disorders such as hemophilia or von Willebrand disease, while abnormal coagulation can lead to thrombosis.

In water and wastewater treatment, coagulation refers to the addition of chemical coagulants, such as alum or ferric salts, to neutralize the surface charges of colloidal particles and promote their aggregation into larger flocs. This is followed by flocculation, a gentler mixing step that builds even larger aggregates for easier removal by sedimentation or filtration. The efficiency of coagulation depends on pH, coagulant type and dosage, temperature, and mixing conditions, and is often paired with flocculants for improved solids removal.

Clinical and industrial contexts also use coagulation as a diagnostic or processing concept; in clinics, tests like PT and aPTT assess the coagulation system, while in industry, controlled coagulation is key to water quality and process efficiency.