Activated Carbon Filters (ACF)
Activated carbon (AC) is similar to ion exchange resin in density and porosity. It adsorbs many dissolved organics and eliminates chlorine or other halogens in water. It does not remove salts. AC filters are one of the only low-cost methods available to remove low-molecular weight (<100 MW) organics and chlorine.
Granular activated carbon is made from raw organic materials (such as coconut shells or coal) that are high in carbon. Heat, in the absence of oxygen, is used to increase (activate) the surface area of the carbon; this is why these filters are sometimes referred to as “charcoal” filters. The activated carbon removes certain chemicals that are dissolved in water passing through a filter containing GAC by trapping (adsorbing) the chemical in the GAC.
Activated Carbon (AC) filtration, as with any water treatment method, is not capable of removing every possible type of contaminant. For example, sodium, microbes, fluoride, and nitrates cannot be removed with AC filtration. Water softening also cannot be achieved with AC filters. In addition, heavy metals, such as lead, can only be removed with a very specific kind of activated carbon water treatment, which is typically used only in residential point-of-use filters.