Activated Carbon FAQ’s
What is Activated Carbon
Using carbon as a filter media dates back many centuries to the Egyptians who used the charcoal for medical purposes around 1500 bc. The romans are also known to have used charcoal as a filtration medium to filter such fluids as water and beer. During the 20th century the uses of activated carbon have multiplied as the pace of technology has accelerated. Activated carbon has a unique position amongst filter media and has become an important part of environmental protection and a leading component in the prevention of air and water pollution.
How does Activated Carbon work
Carbons success is due to its extremely high internal surface area and network of pores within each granule. The carbons surface attracts contaminant molecules, which are then held firm by van der Vaals forces. Many different compounds can be absorbed onto the carbon by this process of physisorption.
How is Activated Carbon manufactured
Activated carbon is manufactured from raw materials such as coal, coconut shell and wood. The raw material is first processed to produce a char and then put through a secondary stage called the activation process.
The activation process involves heating the char to 800 to 1000 degrees in an atmosphere of steam. This process develops the high surface area and extensive pore network common in activated carbon granules.
Activated Carbon for Dechlorination
Specialised water uses in brewing, soft drinks and others such as pharmaceutical industries, Require the complete removal of all odour and taste constituents including free chlorine, Before water is acceptable for their particular processes.
Activated carbon is capable of the removal of all such constituents including chlorinated hydrocarbons, as well as the removal of free chlorine, which may have been previously introduced to render the water biologically sterile.
Activated Carbon for Industrial effluent and wastewater
Activated carbons are effective adsorbents for the traces of herbicides, pesticides, fungicides and insecticides, which ultimately find their way into surface waters.
The majority of these compounds are of very low solubility and are ideal subjects for physical absorption. Detergents and surfactants in general can be adsorbed in high efficiency, a property that is of great value when materials, which are resistant to biological degradation, must be removed.
Activated carbons also display high efficiencies when used for the screening of industrial effluents. Solvents, which may be toxic to the fauna of receiving streams, can be removed on a cyclic basis in many instances.
Carbon s may be used directly in physio chemical processes or may be used in conjunction with biological processes to produce high-grade effluents for recycle or disposal. This is particularly important where strict water authority standards must be met.
Activated Carbon in relation to Ozone
Ozone is used extensively in the water treatment industry for the oxidisation of species which may cause a problem in potable water supplies.
The role of activated carbons in such systems is to remove those materials, which may undergo partial or degradation or may resist oxidation under prevailing conditions.
Ozone has a relatively low stability level in water and provides no residual sterility.
In certain wastewater treatment processes ozone is used to degrade recalcitrant materials, which may be then physically adsorbed onto activated carbon beds.
The carbon can support large bacterial colonies, which utilise adsorbed materials and greatly prolong the life of such beds.
Excess ozone in the system degrades at the carbons surface and in doing so provides an oxygen rich environment for the colonising species.
Ozone is also used in the treatment of water in municipal swimming pools, where it is finding increasing favour due to the facts it does not produce any by products of the type produced by chlorine.
Activated carbon is the medium, which can be used to adsorb breakdown products and to remove residual ozone concentrations prior to recirculation.
Colonisation cannot be tolerated in this instance and carbons containing a bacteriostat are produced for this purpose.