Flocculant is a commonly used water treatment agent in the field of sewage treatment. It can reduce or eliminate the precipitation stability and polymerization stability of dispersed particles in water, and agglomerate and flocculate dispersed particles into aggregates to remove a class of substances. According to chemical composition, flocculants can be divided into three categories: inorganic flocculants, organic flocculants and microbial flocculants.

The following mainly introduces the more commonly used organic flocculant-polyacrylamide. Organic flocculants can be divided into anionic, cationic, non-ionic, and amphoteric types according to the charge properties of the charged group of polymerized monomers, and can be divided into two categories: synthetic and natural polymer flocculants according to their sources .