Activated carbon, also called activated charcoal, is a form of carbon that has been processed with oxygen to create millions of tiny pores between the carbon atoms. This increases the surface area of the substance from 500 to 1,500m2/g, or 300-2,000 square meters per gram. One pound of activated carbon has the surface area equivalent of six football fields.


The increased surface area of activated carbon makes the material suitable for adsorption, a process by which impurities in substances such as fluids, vapors or gas are removed. Impure molecules are held within the carbon’s internal pore structure by electrostatic attraction or chemisorption. The adsorption process helps carbon reduce dangerous matter, activate chemical reactions, and act as a carrier of biomass and chemicals.

Activated carbon is usually made from charcoal, but can be produced from wood, peat or even coconut shells. There are over 150 grades of activated carbon, each with their own uses and applications.

Typically, powdered activated carbon is dosed into the process stream (gas or liquid) and, after a certain contact time, separated by filtration or settling. Some of the issues involved: required contact time, dosing system, single or multi-stage dosing, carbon separation, safety measures.

Granular Activated Carbon (GAC) is mostly used in fixed filter beds, or alternatively in (pseudo) moving filter beds. Some of the issues involved: required contact time (alternatively: hydraulic space velocity), permanent or mobile filter vessels, filling and emptying facilities, safety measures. Further, a crucial consideration regarding GAC refers to possible regeneration, in situ or off site.