This is the final article in a three-part series discussing
water chemistry and technology basics.
In this last section of a three-part series, the use of ozone, ionization, distillation and aeration is discussed in a simple fashion to help the beginner rationalize the importance for a full understanding of these technologies and the need, again, for a professional water treatment specialist. Each of these subjects has had much written about them, and an assault of information in magazines, books, libraries and the Internet can be found. Water treatment and the technologies involved are vast and complex, as is the water to be treated. No two water sources ever seem to be the same, and what may work for one source and application may fail with another. A high-quality analysis of both the application and the raw water needs to be addressed before a treatment can be rendered.
Ozone
Ozone, or O3, has been around since time began. Lightning
produces ozone during thunderstorms and cleanses the air. The sun produces
ozone when it strikes hydrocarbons in the atmosphere and cleanses the air we
breathe by producing ozone with ultraviolet (UV) light. O3 is a naturally
occurring, strong oxidizing and disinfecting agent. Elemental oxygen exists as
two atoms of oxygen combine to form the O2 molecule. An unstable allotropic
form of the gaseous oxygen occurs when UV rays from the sun strike the O2
molecule, break the bonds and form single oxygen atoms. A portion of these
split atoms recombines with other O2 molecules to form O3. The energy released
by lightning produces the same results and one can smell the fresh scent of the
air after a thunderstorm. Photocopying machines and other electrical equipment
produce ozone in small but noticeable quantities as well. Even though ozone has
been protecting mankind since the beginning of time, it wasn’t until 1783
that a Dutch scientist, Van Marum, made the discovery. Christian
Schönbein, a German scientist, named the substance “ozone” in
1840 after the Greek word “ozein” (meaning to smell) because of its
unique odor. Ozone has a sharp, distinct, pungent odor beginning at
concentrations as low as 0.02 ppm. Inhalation of ozonated air with one-tenth of
a part per million by volume may cause irritation of the eyes, upper respiratory
system and lungs as well as headaches.
Manufactured ozone generators produce O3 by exposing oxygen
molecules to UV radiation or high electrical discharge. The weak bond in ozone
makes this substance very unstable and, due to this instability, an oxidizing
reaction occurs. The collision between the ozone molecule and an oxidizable
substance such as inorganic materials (i.e., iron and manganese) or organic
materials (i.e., plastics, rubbers and microorganisms such as bacteria, viruses
and parasitic cysts) make this substance very good at removing or precipitating
contaminants out of water and air.
Ozone has been used for many years in water treatment.
Documentation dates back to 1906 when the municipality of Nice, France, used
ozone for disinfection of its drinking water. The first commercial pool in the
United States to use ozone was in Brynam, N.J., dating back to 1937. An ozone
system was displayed at the New York’s World Fair in 1939 and was touted
as the future of water treatment. The first ozone water treatment system to be
used for municipal water treatment in the United States was used in Whiting,
Ind., in 1940. Since that time ozone has gained wider acceptance, and the
technologies used to produce ozone have become more cost efficient. Los Angeles
and Dallas have the largest ozone plants in the world for treating their
cities’ drinking water, and Las Vegas, Nev., began construction in 1998
of a treatment facility that is just as large. So, ozone is not new but is more
accepted and cost-effective and is becoming a viable option in the water
treatment industry.
Without going into a lot of detail on the properties of
ozone as they are very complex, the uses of ozone are numerous if applied
correctly and dosed properly. Ozone is not the cure all by any means, but it
does have advantages over chemical dosing and is safer and more environmentally
friendly. It is the most powerful oxidizer that can be safely used in water
treatment. Not only is it great for treating drinking water, its use is widely
applied in bottled water plants, ultrapure waters, swimming pools, spas, ponds,
cisterns, breweries, aquariums, soft drinks, cooling towers and many other
applications. Remind customers that this treatment technology needs to be
addressed by a water treatment professional who has experience in this field in
order to achieve the desired end results.
Distillation
Distillation is another technology that has been around a
long time and even today continues to be used as a water treatment solution.
The basic concept is seen in nature as the hydrological cycle. As the sun
evaporates water from sources such as lakes, streams, rivers and oceans the
vapor contacts cooler air and recondenses to form dew or rain. This process is
imitated artificially and more rapidly than in nature by using alternative
sources of heating and cooling. Anyone who has accidentally boiled a pot of
water until there was no water left is familiar with this process and the crust
of contaminants left behind after the water is gone. Distillers use this same
process, but they capture the steam. As the steam is condensed back into the
liquid form, it is contaminant-free.
The water is bacterial free, but the cost can outweigh the
benefits. Over the years these systems have become more efficient and
cost-effective for producing larger amounts of water. Some systems can produce
millions of gallons of water a day and remove a variety of contaminants if
designed properly. These superheated units use steam pressure to flash vaporize
some of the cooler water in each chamber. Each chamber is self-sustaining in
nature and, therefore, is very efficient with the electric or gas heating
element required. Both the multistage and vapor compression distillers can
incorporate various forms of filtration to make up an effective treatment.
These systems require water that is softened in order to be practical to
prevent debilitating scaling and the resultant heat transfer losses and
maintenance costs. Distillation is used in arid regions that are adjacent to
oceans for distilling seawater for drinking water. Distillation also has been
used for removal of such impurities as arsenic, benzene, lead, nitrates,
trihalomethanes and radium, to name a few.
Aeration
Aeration is a method that is used by nature as a means of
water purification. This method has been observed by everyone who has seen a
waterfall, crashing wave or white-water rapids. All of these methods transfer
air into water and provide oxygen so the aerobic bacteria can survive. Aerobic
bacteria require oxygen to survive and decompose plant material in water.
However, these “good bacteria” need oxygen to work and burn up the
supply of oxygen in the water. When the oxygen in the water is exhausted,
anaerobic (or non-oxygen using) “bad” bacteria begin to decompose
the plant material, and this is when water begins to smell and taste bad due to
gasses that are released. Ferrous iron becomes ferric iron when exposed to
oxygen. Aeration is a method to precipitate this type of iron into an insoluble
form of iron that can be filtered. Other impurities such as hydrogen sulfide
can be aerated out of water. Ponds, cisterns and lagoons can use aeration
devices that use an air stone to transfer air to water. Water that becomes
stagnant begins to grow algae and waterborne parasites.
Ionization
Ionization is defined as the loss or gain of an electron.
Copper and silver ionization is the loss of an electron that is created by
applying a charge to an anode and forcing the electron off and into the stream
of water. This small particle that becomes suspended in the water has bacterial
disinfection qualities. Colloidal copper and silver have significant effects on
many bacteria, viruses and impurities in water. Copper is very effective
against algae and this electrically charged water also keeps bicarbonates such
as calcium and magnesium in suspension longer by reversing the effects of static
electricity caused by the flow of water within a pipe. This phenomenon reduces
the risk of scaling in pipes because of these heavy minerals.
Other benefits also have been observed. The reduction of
chlorine is one effect that is caused by the use of ionization. Since the
copper and/or silver take the brunt of the disinfection process, the need for
chlorine is reduced. Swimming pool owners and cooling tower operators have used
this method of water treatment for a number of years. There have been many studies
done that prove this method of bacteria and algae reduction is effective.
Copper and silver ionization is not new technology but, like
ozone, it has not been used, understood or applied correctly. This type of
water treatment dates as far back as the Egyptian era when they used copper and
silver containers for water. In addition, the pioneers crossing the United
States used copper and silver coins for water purification. Copper pennies
thrown in wishing wells helped keep the bacteria and algae from growing.
However, today we use electronic controllers to dose the correct amount of
copper into the water, and each application can benefit when properly measured
and applied.
As one may have learned from all the technologies that have
evolved over the years, water treatment is an interesting and challenging
occupation. The science of water chemistry and the understanding of water
treatment technology are very complex. Every water source and application in
the world is slightly different, and the desired result can be a challenge for
a water treatment professional. The preceding articles only scratched the surface
of what is available in water treatment and how to treat water effectively and
efficiently. A knowledgeable water specialist should be employed with most
every water treatment so the proper analysis can be made and the best method of
treatment determined.
Parts one and two of this article may be viewed in the
article archives at www.waterinfocenter.com.
