A coagulant binds together very fine suspended particles into larger particles that can be removed by settling and filtration. It is an alkaline compound that is added to the water for pH adjustment. Since filter alum is an acidic salt, it lowers the pH of the water, and lime is used to neutralize this effect. Chlorine destroys pathogenic microorganisms, oxidizes undesirable elements such as iron and manganese and reduces some tastes and odors. Before the use of Chlorine, water-borne diseases such as typhoid fever were the source of devastating epidemics.
Chlorine is the most important chemical added to water in terms of public health.
Mainly because of safety concerns, Greensboro switched from Chlorine gas to Sodium Hypochlorite in 1999. Sodium Hypochlorite, NaOCl, is a clear, greenish-yellow solution commonly used in bleaching. When necessary, Hypochlorite is also added in the distribution system to assure adequate levels of Chlorine for disinfection. Calciquest is designed to sequester iron, manganese and calcium to keep them in solution. It also provides a tough monomolecular film on the interior surface of water lines to prevent corrosion.