Granular activated carbon (GAC) is a proven option to remove certain chemicals, particularly organic chemicals, from water. GAC also can be used to remove chemicals that give objectionable odors or tastes to water such as hydrogen sulfide (rotten eggs odor) or chlorine.
Granular activated carbon (GAC) has been used as a substitute for granular filter media and as an additional process in conventional treatment plants for the removal of organic compounds including compounds producing taste and odors, pesticides, and other synthetic organic compounds. GAC can be manufactured from a large variety of materials including wood, nuts, shells, coal, peat, or petroleum residues. GAC used in water treatment plants is typically manufactured from bituminous or lignite coal by heating the coal under anaerobic conditions. The product of this process is then activated by exposure to a mixture of steam and air at a temperature of 1500 °F, which oxidizes the surface of the carbon pores and allows the surface to attract and hold organic compounds. After being used at a water treatment plant, the spent GAC can be regenerated through steam, thermal regeneration, and chemical means.
