What are coagulants and why are they important?

Coagulants are chemicals used in the coagulation process in which suspended colloidal particles in wastewater are destabilized or electrically neutralized, so that the particles can collect and settle out of the water. Colloidal particles are insoluble particles that are dispersed throughout another substance. Coagulants are typically used in combination with flocculants in wastewater treatment process prior to clarification in order to condense the solid waste for the settling process. 

Coagulants can come in both inorganic and organic compounds, and depending on the desired outcome of the product they can be used to either change the insoluble particles chemically or physically.