Chlorine: water after it was discovered that micro-organisms





Removing Contaminates from Water





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22, 2017

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, pp.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). When these substances are heated the bonds are
broken, causing manganese chloride (MnCl2), water (H2O)
and chlorine gas (Cl2) to form (Lenntech, Water Treatment Solutions). 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.”

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. It
is not only used as a disinfectant, but it is also a constituent of various
medicines. The majority of our medicine contains chlorine or are developed
using chlorine-containing byproducts (Lenntech, Water Treatment Solutions).
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”

Chlorine 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). There is no preferred
method out of the three, as they all do, essentially, the same thing, although
some consumers pre- and post-chlorination as it is the most thorough cleaning

Chlorine can also be dangerous in
the sense that it can form extremely reactive and toxic products (such as
hydrogen chloride—HCl). As mentioned above when hydrogen chloride dissolves
in water it becomes hydrochloric acid. These ions react with any kind of
substance they come in contact with, even metals that are corrosion resistant
under normal circumstances. Concentrated hydrochloric acid can 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’.

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.

            In 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 we are today, in
the sense of clean and drinkable water, without it.




















Works Cited

Bengtson, Harlan. “The History of Water Chlorination
– A Major Public Health Advance.”   

Brighthub Engineering,
13 July 2010, p.1-13

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

Environmental 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.

Huang, 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.

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

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

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

National 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,

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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