Activated carbon (AC) units are usually installed as point-of-use
(POU) systems. They
are generally placed at the kitchen faucet and used to purify water intended for
drinking and cooking purposes only.
Carbon Filtration - Activated carbon filters
are primarily used to remove taste, odor and some of the contaminants in water supplies.
AC is effective at removing organic compounds such as volatile organic
compounds, chlorine, pesticides, trihalomethanes and benzene and gasoline. They
are moderately effective at removing removing metals that are bound to organic
molecules, chloride and radon. They are an efficient, cost-effective means of
treating your water.
Activated carbon is an extremely porous, black solid substance with a very large surface
area resembling granular or powdered charcoal. An ounce of AC has an
estimated 30,000 square yards of surface area. Contaminants accumulate
on the surface of the AC in a process called adsorption.
Activated Carbon is effective at filtering or
- chlorine, lead, mercury, radon
- hydrocarbons, pesticides, PCBs
- volatile organics like benzene
Activated Carbon (AC) filters eventually become fouled with contaminants and loses
to adsorb pollutants. At such time, the filter needs to be replaced.
Eventually, the surface of the AC will be
saturated with adsorbed pollutants, and no further purification will occur. This
is called breakthrough - the pollutants have broken through the filter to emerge
in the treated water. An AC
filter may become fouled before they slow water passing through, in this
case contaminants will pass through into your drinking water while the filter
appears to be functioning normally. Worse, an AC filter can support
bacterial growth. Condition for bacterial occurs when the filter is saturated with
organic contaminants. It is unclear
whether the bacteria growing on the carbon poses a health threat.
It is difficult to know when to replace the various components
of an RO system.
Verification of a system's performance can only be determined by chemical
Rust, scale, sand or other sediments can clog
an AC filter. One solution to
this problem is to place foam, paper or cotton filters (often called sediment or fiber
filters) between the cartridge and incoming water. When the sediment
clogged, it can be replaced more cheaply than the replacement of the AC filter.
Physical and chemical characteristics of the water will also affect
performance. The acidity and temperature can be important. Greater acidity and
lower water temperatures tend to improve the performance of AC filters.