Polyamine is a water-soluble cationic polymer widely used as a coagulant in water and wastewater treatment. It contains multiple amine functional groups that carry positive charges, enabling it to neutralize negatively charged colloids and suspended solids. By reducing electrostatic repulsion, polyamine promotes particle aggregation and rapid floc formation. Compared with inorganic coagulants, polyamine produces less sludge and works effectively over a wide pH range. It is commonly applied in drinking water treatment, industrial wastewater clarification, sludge dewatering, papermaking, and oilfield water treatment. Polyamine is valued for its fast action, high efficiency, and compatibility with other flocculants.