Granular Activated Carbon (GAC) adsorbs dissolved organic contaminants from
water into its structure. GAC Towers are usually proceeded by a conventional
water treatment plant to pretreat the raw water. Contaminants removed by GAC
include taste and odour, VOC's (volatile organic chemicals -
trichloroethylene), SOC's (synthetic organic chemicals - pesticides) and
polynuclear aromatic hydrocarbons (Nepheline).
GAC's are very effective at removing taste and odour problems from drinking
water as well as providing a barrier to organic based chemical spills.
There are many design parameters in choosing the correct GAC tower, which are
dictated by the contaminant(s) and its concentration. Variables in design
include: choice of carbon (lignite, peat, bone bituminous etc.), empty bed
contact time (EBCT), bed surface loading rate and carbon particle size.