Solids in water refer to suspended or dissolved materials in drinking, surface and brackish waters, as well as domestic and industrial wastewaters. Solids may affect water and wastewater quality in a number of ways. Waters with high dissolved solids are generally of lower quality and may cause adverse physiological responses in the consumer, so a maximum of 500 mg of solids per liter is desirable for drinking water.

The separation of fine and colloidal particles takes a long time, so chemical coagulants are used to enlarge the particles and reduce the settling time. When the coagulant is added to water, some of it is used to adjust the electrical potential of the particles, and some of it is combined with the alkalinity of the water.

Coagulants are key components for the wastewater treatment process that stick to the suspended solids and settle them so that they can be easily removed and the treatment process is carried out. It is very important to choose the type and amount of coagulant to prevent non-compliance and overdraft as well as to reduce the cost of consumption. The appropriate and practical choice of a coagulant can be critical for the success of a process. Coagulants are used to remove the disorganization of colloidal suspensions and neutralize suspended solids.