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Removing Contaminates from Water





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22, 2017

            To quote Lyle Hurd, “What a paradox,
that water, the essential nutrient, the exlir of life, contains potentially
toxic elements that could jeopardize the immune system, leaving us vulnerable
to organ damage and deadly disease.” Chlorine has disinfected drinking water
for over a hundred years (Huange, 1401). It was introduced to create an
essentially, “safer” and “healthier”, water for us to drink. It is now used
every day in our drinking water to help prevent epidemics. As water is the most
abundant compound in the human body (Hurd, 42) it is extremely important to
find ways to keep it both clean and safe for the public to drink. Chlorine is
said to be one of the strongest advances in disinfectant history. There are
many uses for chlorine and chlorination was experimented with in many different
ways before it was decided that chlorine gas be used to treat the water and
before the chlorine dioxide that is used in pools was discovered.  

Chlorine was supposedly discovered in the
thirteenth century, but was first created into a pure substance by Carl Wilhelm
Scheele in 1774. Scheele heated brown stone (manganese dioxide; MnO2)
with hydrochloric acid (HCl) (Lenntech). When these substances are heated the
bonds are broken, causing manganese chloride (MnCl2), water (H2O)
and chlorine gas (Cl2) to form (Lenntech). Chlorine gas was first
introduced as a method to clean drinking, or potable, water in 1903 in Middlekerke, Belgium. But, before then, it had only
been used as a cleaning solution and a sort of precaution in places such as
hospitals—as a type of ‘industrial soap’. It was only thought to be put into
drinking water after it was discovered that micro-organisms caused the majority
of diseases. Chlorine was first used in the U.S.
as a major disinfectant in 1908 in Jersey City, New Jersey (Centers for Disease
Control and Prevention, 1), specifically at the Boonton reserve. By the
late 1920s, the chlorination of drinking water was said to have virtually eliminated all waterborne epidemics and
diseases from the U.S. and LIFE magazine recently cited the filtration
of drinking water and use of chlorine as “probably the most significant
public health advance of the millennium.”(Scientific American).

has freed civilization from the constant dangers of waterborne epidemics that
once inflicted suffering, disease and premature death (Hurd, 42). The world
can credit the chlorination of drinking water with the responsibility for a
large part of the 50 % increase in life expectancy (Bengston, 2). As a primary
disinfectant, chlorine is applied to disinfect and to control microbial
activity in the distribution system (EPA, Water Treatable Database). Now,
Chlorine is even added to the public water supplies to kill disease-causing
microbes (Keiley, 68). Chlorine plays an important role in medical science
(Lenntech). It is not only used as a disinfectant, but it is also a constituent
of various medicines (Lenntech). The majority of our medicine contains chlorine
or are developed using chlorine-containing byproducts (Lenntech). Even
pain relievers such as Acetaminophen or in
antibiotics such as Vancomycin.

Chlorine is added to the water in public
water reserves, giving those with access to the public or ‘city water’ the
chlorinated water. Those with a well or private water supply have the choice to
add in their own chlorine, although this process can be dangerous if not done
correctly with aqueous chlorine, as chlorine gas is toxic. People on private wells don’t enjoy the
benefit of having someone else monitoring contaminant levels in their water so
they must be diligent about testing it themselves and maintaining their wells
(Keiley, 68). It is a long and difficult process for most, as extra steps and
precautions must be followed.

Although in public water supplies, the
chlorine is always added in its gas form, its solution/liquid form (NaOCl) is
considered a better choice for private consumers, because when small amounts of chlorine are breathed in even
during short time periods, this can affect the respiration system (Lenntech). “Pure
chlorine is very toxic, even small amounts can be deadly. During World War I
chlorine gas was used on a large scale to hurt or kill enemy soldiers”

is available as compressed elemental gas, sodium hypochlorite solution (NaOCl)
or solid calcium hypochlorite (Ca(OCl)2). All forms of chlorine,
when applied to water, form hypochlorous acid (HOCl). Gaseous chlorine
acidifies the water and reduces the alkalinity, whereas the liquid and solid
forms of chlorine increase the pH and the alkalinity at the application point
(EPA). Chlorine can be added for disinfection to drinking water in several
different ways. When ordinary chlorination is applied, the chlorine is simply
added to the water and no prior treatment is necessary. Pre- and post-chlorination
is adding chlorine to water prior to and after other treatment steps. Rechlorination
means the addition of chlorine to treated water in one or more points of the
distribution system in order to preserve disinfection.” (Lenntech, Water Treatment

There is no preferred method out of the three, as they all do, essentially, the
same thing. Although, the more informed consumers prefer pre- and
post-chlorination as it is the most thorough cleaning process.

Chlorine can also be dangerous in the
sense that it can form extremely reactive and toxic products (such as hydrogen
chloride—HCl) (Lenntech). When hydrogen chloride dissolves in water it becomes
hydrochloric acid (Lenntech). These ions react with any kind of substance they
come in contact with, even metals that are corrosion resistant under normal
circumstances (Lenntech) for example; some forms of concentrated hydrochloric
acid even corrode stainless steel. This is why it is stored either in glass or
in plastic (Lenntech) and cannot be dealt with directly, or by consumers. And
although dangerous, Chlorine is used to kill bacteria—or used in our medicines
as discussed above—for the same reasons. When chlorine reacts with organic
substances, it often takes less than a minute to kill off the bacteria of
everyday use (for example with E. Coli) which is faster than some synthetically
prepared disinfectants. It can even kill Hepatitis A in only 16 minutes, leading
consumers to believe that it was the ‘all-powerful cleaner’.

            Although Chlorine had been the
principle disinfectant of community water supplies for several decades (National,
4) and it was already such a big and proclaimed improvement in the water
treatment industry, scientists still searched for a stronger and more cost effective
solution to treat drinking water. This led them to the use of chlorine dioxide,
an easier to control cleaner. The switch from chlorine to the even more
powerful chlorine dioxide was an easy decision; Chlorine dioxide was a stronger
disinfectant, thus requiring a lesser concentrate (less of the element needed
also helped reduce costs for the government). This new alternative could also
be used for the control of iron, manganese, and taste and odor causing
compounds (Volk, 323-324). In fact, it was such an improvement that the U.S. Government
took a mere 14 days for the switch between chlorine and chlorine dioxide.

Yet, not everyone was happy or educated
enough to appreciate the switch. Chlorine dioxide has an intense greenish
yellow color with a distinctive odor (Gordon, 204). Due to this slight change, the
general public was concerned with the change in water treatment. Consumers
had complaints of taste, odor, and (or) water discoloration (Volk, p.324).
Most governments had to switch back to chlorine for the main-stream drinking
water treatment, but continued to use chlorine dioxide in pools like we
continue to do now, as it can battle stronger bacteria’s such as feces.

conclusion, chlorine is a powerful and useful element in the disinfectant
world. For the past hundred years, it has protected us from certain-death
epidemics and acted as a booster to keep our bodies in tip-top shape. From the
use of the general public to private homes, the chlorination of water has
become a large part of our lives. And although the change to chlorine dioxide
was unsuccessful, it continues to clean our pools. Rick Hind, the legislative director at Greenpeace USA, once called Chlorine “the replaceable chemical” and yet the world would not be where it is today, in
the sense of clean and drinkable water, without it.














Works Cited

Harlan. “The History of Water Chlorination – A Major Public Health

Engineering, 13 July 2010, p.1-13

for Disease Control and Prevention. “Drinking Water.” Centers for Disease Control and Prevention, 22 June 2015, p.1-2,

Protection Agency, United States. “Water Treatability Database.” EPA, Environmental Protection Agency, 5
Feb. 2007, p.1-2,

Gordon, Gilbert, Aaron A. Rosenblatt.
“Chlorine Dioxide: The Current State of the Art.” Ozone: Science &
Engineering, vol. 27, no. 3, 2005, pp. 203–207.

Miao, and Yiping Hang. “Ion Chromatography for Rapid and Sensitive
Determination of Total Chlorine in Water.” Analytical
Letters, vol. 45, no. 11, 15 July 2012, pp. 1401–1411.

Lyle. “Water: The Essential Nutrient.” Total
Health, vol. 25, no. 4, Aug. 2003, pp. 42–43.,

Lynn. “Safe Drinking Water.” Mother Earth
News, no. 198, June/July 2003, p. 65.

Lenntech. “Disinfectants—Chlorine”
Water Treatment Solutions. Lenntech Water Treatment & Purification,

Research Council (US) Safe Drinking Water Committee. “The Chemistry of
Disinfectants in Water: Reactions and Products.” Drinking Water and Health: Volume 2., U.S. National Library of
Medicine, 1 Jan. 1980,

American. “How does chlorine added to drinking water kill bacteria and other
harmful organisms? Why doesn’t it harm us?” Scientific

Volk, C J, et al. “Implementation
of chlorine dioxide disinfection: Effects of the treatment change on drinking
water quality in a full-Scale distribution system.” Journal of Environmental Engineering and Science, vol. 1, no. 5,
Sept. 2002, pp. 323–330.



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