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Introducing
of activated Carbon
Activated carbon is a
very mature technology that is designed to help remove taste and odor from
water through adsorption of the compounds that cause problems.
There are a variety of different types of carbon that are used
industry-wide. They include wood, lignite, coal, and coconut as the most
common sources for activated carbon.
Activated carbon operates
through adsorption. Adsorption is a surface phenomenon and is therefore
directly related to the surface area of the media. In the case of activated
carbon, the surface area is related to the pore structure of the raw
materials. The cost of the media is also related to the raw materials, so
there are other factors that must be taken into consideration besides the
total surface area.
Adsorption takes place due to
intramolecular attraction between the carbon surface and the substance that
is being adsorbed. The force of the attraction can be altered by increasing
the density of the carbon or by reducing the distance between the carbon
surface and the substance being adsorbed (typically by reducing the median
pore size). As the fluid (often water) passes over and through the carbon,
the attractive forces between the compounds that are the most attracted to
the carbon are adsorbed onto the surface. The compounds that are the most
highly attracted are typically organic compounds (which can cause taste,
odor and appearance problems), volatile organic compounds (VOCs) and
halocarbons such as trihalomethane (THM) compounds and other process
wastes.
Once all of the surface area
of the carbon has been exhausted through adsorption, the carbon can be
regenerated in a number of different manners. The most common is offsite
furnace re-activation which involves heating the carbon up to drive off the
organic materials that are adsorbed.
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