Flocculant: It is a kind of thing that can reduce or eliminate the precipitation stability and polymerization stability of dispersed particles in water, so that dispersing particles condense and flocculating into aggregates. According to the chemical composition, flocculants can be divided into inorganic flocculants, organic flocculants and microbial flocculants three categories. Inorganic flocculants include aluminum salts, iron salts and their polymers. For example: polyferric chloride, polyaluminum chloride, polyferric sulfate, ferrous sulfate, ferric chloride, etc. Organic flocculants, the organic coagulants used in sewage treatment are mostly water-soluble linear polymer substances. 80% are polyacrylamide products.