Carbon filtering is the mode of filtering that utilizes a bed of activated carbon for eliminating contaminants and impurities, by using chemical adsorption. Each granule and particle of carbon gives a huge surface area or pore structure, enabling contaminants the maximum possible contact to the active sites in the filter media.
Activated carbon works through the process referred to as adsorption, whereby the pollutant molecules present in the fluid to be treated are trapped in the pore structure of the carbon substrate. Carbon filtering is usually used for the water purification, air purifiers and the industrial gas processing, for instance the elimination of the hydrogen sulfide and siloxanes from the blogas. It is also utilized in many other applications like respirator masks, purification of sugarcane and in precious metals recovery, especially gold.
As far as the types of carbon filter are concerned, there are two major types of these filters that are used in filtration industry; powdered block filters and the granular activated filters. Generally, the carbon block filters are considered more effective for eliminating lager amount of contaminants on the basis of the increased carb surface area. There are a lot of carbon filters that also utilize secondary media like silver for preventing bacteria growth in the filter. As an alternative, the activated carbon might itself be impregnated with secondary material for giving this bacteriostatic quality.
Carbon filter have been in use for few hundred years and are taken as one of the oldest modes of water purification. At present, these filters are used in residential homes as point of use water filters, landfill leachate, groundwater remediation, industrial wastewater and on occasion basis in municipal water treatment plants. These are also used being pre-treatment devices for reverse osmosis systems and as tailored filters developed to eliminate chlorine-resistance cyst like cryptosporidium and giardia.