Flocculants are chemicals that bind fine particles of the dispersed phase in aggregates, causing sediment to precipitate out of the colloids.

Flocculants have the ability to interact with and form chemical bonds on the particle surface of the dispersed phase. As a result of adsorption, the so-called flocculi are formed on particle molecules to initiate the coagulation of emulsions. The next stage is the creation of large aggregates, which precipitate out of the solution in the form of a sediment or turbid suspension. They can be separated from the water by sieves or by filtration or decantation. Flocculation can be accelerated by gently mixing the system. The flocculants then reach the particles faster and encapsulate them to form larger aggregates that can be removed more quickly.

Polymer compounds such as polyacrylamides, polyacrylic acids and their derivatives are used as flocculants. They are characterized by good solubility in water and high biodegradability.

Three types of flocculants are distinguished based on their chemical nature:

• anionic flocculants – used in alkaline and neutral environments; they are used mainly for clarifying and dehydrating mineral suspensions,
• cationic flocculants – used in acidic environments; most commonly used to clarify suspensions of organic substances,
• inert flocculants – have the widest range of applications in various industries, e.g. coal and metal ore processing.

Flocculants are used in sewage treatment plants, water treatment plants and in many industrial processes where it is necessary to separate products suspended in colloidal form.