Delivering Clean Water With Ceramics

tech emphasis filtration
Delivering Clean Water
With Ceramics
By Tim Evans
Ceramic filter
technologies remove
pathogens and
improve water quality
N
early two centuries after
Henry Doulton invented
it, the ceramic water filter
continues to be manufactured by the
millions. It plays a significant role
in the provision of clean, safe water
throughout the world.
The filter elements are produced
using modern manufacturing techniques to provide a hollow, porous
ceramic that is fired at temperatures
in excess of 1,830°F. They are most
often made from diatomite, which in
its raw state is a chalky, fine-grained,
low-density material.
Diatomite contains a high
percentage of silica, has a cellular
nature, and is characterized by
a porosity of around 80%. Most
people think of ceramics as brittle,
but the way the shaped diatomite is
sintered, often with organic binders
and lubricants, aids densification and
produces a strong final component.
Why Ceramic?
The smaller the pore size in the
filter wall and the more tortuous the
path the water must follow, the more
effective the particle removal process.
Ceramics have a small, complex,
interconnected pore structure—sometimes down to 0.2 µ—making them
ideal for the job.
Furthermore, major manufacturers
such as Fairey Industrial Ceramics,
which has been producing the Doulton
range for 187 years in the U.K., are
able to accurately control this pore
structure, thus ensuring product
consistency. Ceramic filters are chemically inert, so they can be used right
away or brought out of storage after
many years, and will perform with
identical effectiveness.
Shaping Up
Figure 1: Multi-Stage Filtration Using Ceramic Filter Cartridges
Water passes from the outside
to the inside of the candle.
Filtered water exits
through the candle mount.
Stage 1: Outer ceramic
shell – microfiltration
Stage 2: Anti-bacterial formula within the
ceramic gives bacteriostatic protection
Stage 3: Activated carbon block integrated inside certain
filter candle grades removes chlorine, chloramines,
organics and VOCs, improving taste and odor
Stage 4: Heavy metal removal media also can be
incorporated in the carbon block to remove lead
Stage 5: Slow-release scale inhibitor reduces
scale build up downstream of the filter
16
Water Qualit y Products
When it comes to the fired ceramic
tubes, there are two established shapes:
the candle and the cartridge, designed
in such a way that the water passes
from the outside to the inside.
Ceramic candles are formed with
a domed, closed end at the base and
are open at the top. The open end is
closed off with a food-grade plastic
mount, which enables the candle to fit
into a filter housing.
By contrast, ceramic cartridges are
formed with both ends open, which
also are closed off with plastic mounts.
The mount at the base is completely
closed, while the one at the top has an
opening through which the filtered
water flows after it has passed through
the ceramic.
In both configurations, ceramic
tubes offer a rigorous two-stage filtration process—surface filtration and
then depth filtration—in order to trap
particles and pathogens.
In surface filtration, particles larger
than the pore cannot pass through,
and smaller particles hitting the pore
at the same time collide, adhere and
form a bridge. Additionally, due
to inertial mass, particles do not
Ceramic filters are effective at removing
pathogens from drinking water. The addition
of other media, such as activated carbon or
ion exchange media, can further expand their
treatment potential.
automatically follow the water flow
through the pores anyway, and can
collide with non-porous areas of the
tube wall and be held there.
Particles that do penetrate the
ceramic wall then are subjected to
depth filtration. This works in three
ways. Particles much smaller than
the pores are intercepted within the
ceramic wall, because the water is
forced to flow through a complex
series of labyrinths. The path through
the filter has many sharp angles due to
the complicated ceramic structure, so
particles become trapped within it.
Secondly, as with bridging on the
surface, small particles can combine to
form clusters large enough to become
trapped in dead-end cavities.
Thirdly, dispersion forces cause other
small particles to become attracted to
the ceramic and simply adhere to it in a
process known as adsorption.
The versatility of ceramic filters
also can be enhanced when used in
tandem with special water treatment
cartridges. Typical examples would be
prefilters, to prevent premature clogging of filters in high-sediment areas;
limescale reduction cartridges, for hard
water areas; and fluoride reduction
cartridges, which help reduce both
natural and added fluoride.
Trusted Technology
In addition to removing dirt particles, ceramic filters have been shown
via independent test results to be
effective against pathogenic bacteria,
microbial cysts and heavy metals. At
the same time, they leave the oxygen
and trace mineral content unchanged,
resulting in a clean, fresh taste.
All around the world, wherever
consumers rely on untreated water
supplies, stored water or simply only
have access to polluted water, people
face potentially fatal disease through
the ingestion of pathogenic bacteria.
Added to that is the danger posed
by waterborne microbial cysts—resistant to chlorine treatment—that cause
stomach and intestinal problems,
including potentially life-threatening
diarrheal disease. The size of the threat
cannot be underestimated: Globally,
diarrheal disease kills 800,000 children every year.
When it comes to pathogenic
bacteria, ceramic systems can filter out
the organisms and parasites that cause
cholera, typhoid fever, cryptosporidiosis, amoebic dysentry, colibacillosis,
schistosomiasis and more. Additionally,
The Case for Ceramic
• Effective Barrier: Ceramic in
Doulton systems can remove
virtually 100% of submicron
particles and pathogenic bacteria
from drinking water.
more than 99.99% of microbial cysts
are removed.
Other undesirables elements in
water also can be eliminated. Chlorine
affects both the taste and odor of
water, but is easily addressed with the
addition of activated carbon to the
ceramic filter. Where lead contamination is an issue, the inclusion of an ion
exchange resin effectively deals with
the problem. wqp
Tim Evans is business development
executive (North America) for Doulton
The L-Series!
A patented keyed design and available
a
auto shut-off make the L-Series
ie
es unique!
New Quarter Turn Design for
easy change-outs.
Available with or without auto shut-off.f.
Available with vertical or horizontal
• Anti-Bacterial: The locking of
silver within the ceramic structure
inhibits microbiological growth on
the filter, meaning there is no need
to sterilize the candles.
Patented Keyed design.
Custom Keys available
Variety of media options
• Multi-Stage Filtration: Other
filter media can be put inside
the candles to make them more
effective. Options include activated
carbon to remove chlorine, or ion
exchange media to remove heavy
metals such as lead.
1/4” or 3/8” Quick Connect ports.
available including:
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• Mineral Retention: Minerals that
are beneficial to health are not
filtered out by ceramic; they are
retained in the water.
The Best Inline Water
Filter in the World...
Pure and Simple®.
• Environment: Ceramic filter
candles are a 100% natural product.
• Compliance: Major manufacturers, such as Fairey, are ISO
9001:2008 compliant and hold
NSF Intl. and Water Regulations
Advisory Scheme certificates.
For more information on this subject
write in 1005 on this issue’s reader
service card.
Omnipure Introduces Our
Newest Family Member...
• Long Life: Ceramic filters are
easily cleaned and can be cycled
several times. A useful life of
six months is not untypical. This
makes them cost-effective.
• Inert: Because they are chemically
inactive, ceramic filters do not add
anything to the water.
Water Filters. Evans can be reached
at tevans@faireyceramics.com
or +44.1782.66.44.30.
®
1-800-398-0833 USA
www.Omnipure.com
sales@omnipure.com
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