||Solid Block Activated Carbon (SBAC):
Activated carbon is the primary raw
material in solid carbon block filters; but instead of carbon
granules comprising the filtration medium, the carbon has been
specially treated, compressed, and bonded to form a uniform matrix. The effective
pore size can be very small (0.5 - 1 micron). SBAC, like all filter cartridges, eventually
become plugged or saturated by contaminants and must be
changed according to manufacturer's specifications.
Depending on the manufacturer, the filters can be designed to
better reduce specific contaminants like arsenic, MTBE,
||The advantages of SBAC filters include:
||Provide a larger surface area for adsorption to take
place than Granular Activated Carbon
(GAC) filters for better contaminant reduction.
||Provide a longer contact time
with the activated carbon for more complete contaminant reduction.
||Provide a small pore size to
physically trap particulates. If the pore size is small
enough, around 0.5 micron or smaller, bacteria that
become trapped in the pores do not have enough room to
multiply, eliminating a problem common to GAC
||Completely eliminate the channeling and dumping problems associated with GAC filters.
||SBAC filters are useful in
emergency situations where water pressure and
electricity might be lost. They do not require
electricity (like distillation) to be completely effective, and
water can even be siphoned through them.
||SBAC filters do not waste water like reverse osmosis.
||Many dissolved minerals are not
removed by activated carbon. In the case of
calcium, magnesium, potassium, and other beneficial
minerals, the taste of the water can be improved, and
some (usually small) nutrient value can be
gained from the water.
||Simple, economical maintenance.
Typically an inexpensive filter cartridge needs to
be changed every few months to a year, depending on water use and the
||This combination of features
provides the potential for greater adsorption of many
different chemicals (pesticides, herbicides, chlorine,
chlorine byproducts, etc.) and greater particulate
filtration of parasitic cysts, asbestos, etc. than many
other purification process available. By using
other specialized materials along with specially
prepared activated carbon, customized SBAC filters can
be produced for specific applications or to achieve
greater capacity ratings for certain contaminants
like lead, mercury, arsenic, etc.
|| The disadvantages of SBAC filters
filters, like all activated carbon filters, do not
naturally reduce the levels of soluble salts (including
nitrates), and some other potentially harmful
minerals like arsenic (unless specially designed and
certified to do so) and
cadmium. The fluoride ion is also not removed by
activated carbon. If these contaminants are present in your
water, reverse osmosis would usually be the most
economical alternative followed by distillation.
||As described above, hot water should NEVER be run through a carbon filter
||As SBAC filters remove contaminants from the water they gradually lose effectiveness until they are no
longer able to adsorb the contaminants. There is no easy way to
determine when a filter
is nearing the end of its effective life except that the 'filtered' water eventually begins to taste
and smell like the
unfiltered water. The manufacturer's guidelines for changing filter cartridges should always be followed.
To ensure that marketing claims are accurate, check NSF
International to see if the SBAC filtration system you are
interested in purchasing is certified to significantly reduce the
contaminants you are concerned about.
An example of a certified list of
contaminants significantly reduced by a high-end SBAC filtration
(** at 200 percent of capacity - that's after filtering twice
the rated volume of the filter**)
For Standard 042 -
Chlorine Reduction, Class I (actual chlorine reduction 99.9%)
Particulate Reduction, Class I (actual particulate reduction down to 0.5
Chloramine Reduction (actual chloramine reduction greater than 96%)
Taste and Odor Reduction
For Standard 053 -
contaminants of health concern and measured percent reduction
Asbestos Reduction >99%
Chlordane Reduction >99.8%
Cyst Reduction 99.9%
Lead Reduction >98%
Mercury Reduction >99.3% (pH 8.5) >91.4 (pH
MTBE Reduction 96.6%
PCB Reduction >98%
Toxaphene Reduction >93%
TTHM Reduction (Trihalomethanes) >99.8%
Turbidity Reduction >99%
VOC Reduction (volatile organic chemical) Reduction -
you will see a long list of specific VOCs
reduction for the various VOCs can be found on the product certification
below, but most are 98-99% or more).
For NSF Standard 401 -
Emerging Compounds/Incidental Contaminants
There are 15 contaminants on the list
A few SBAC filtration systems
have also been certified for arsenic reduction: