Geoffrey James
Preventing Contaminants from Entering Your Body: Engineering in Water Purification
Drinking unclean water has cost millions of lives. Unclean water transmits harmful bacteria,
viruses and unwanted chemicals that could be very detrimental to our bodies. This problem has
resulted in numerous life-threatening epidemics taking place throughout history. People have
attempted to develop water purification systems from as early as the ancient Mesopotamian
period, but unseen contaminants continue to cause health problems. These facts drive scientists
and engineers to develop more sophisticated ways to purify drinking water.
Introduction
Human beings have many basic physiological needs that must be met to ensure their survival.
Without food, humans can survive for more than three weeks. On the other hand, without water,
they are only able to survive for at most three days since every living cell inside the human body
needs water to keep functioning [1]. Water is fundamental to sustaining humans’ lives, so our
water supply needs to be kept hygienic. Drinking dirty water is dangerous because it often carries
undesirable chemicals and harmful bacteria that could be damaging to our bodies. Hence, for
scientists and engineers, water purification is a field that has limitless areas for improvement
because purified water standards always become more stringent as new water related diseases are
discovered. Water purification has evolved from a relatively simple process into one of the most
complex engineering processes. Today, technology has advanced so much that it is possible to
create a more advanced water purification process.
Background of Water Purification
Efforts to purify drinking water began in approximately 4000 B.C. The initial development of
water purification techniques began with an attempt to filter the water using charcoal, as is
shown in Figure 1. Once filtered, the water was heated through exposure to sunlight or by
boiling, after which the water was strained. After that, the water was considered potable. Potable
water exclusively refers to safe drinking water, not referring to clean water for washing and
household use. [2]. People measured the quality of their drinking water by its turbidity, or the
state of water clarity. The higher the turbidity, the cloudier the water appeared. This turbidity
level provided an indication of how contaminated the water was [3].
Figure 1. Charcoal Filtration. http://www.practicalprimitive.com/images/newsletters/charcoalfilter/fullfilter.jpg
In early 1700s, water filtration, a process to remove hazardous particles was invented but
filtration only began to get popular in the early 1800s in Europe. At that time, engineers started
to play a role in creating effective water filtration techniques. The problem with filtration at that
time was that there were some contaminants that were not visible to the naked eye, so filtration
alone could not ensure that the water was safe to drink. For example, cholera, a disease that
haunted London in 1854 and killed hundreds of people, is caused by bacteria found in
contaminated water. John Snow, an English scientist, found that an ineffective water filtration
mechanism on one of the street pumps caused the cholera epidemics. This tragedy shows us that
microscopic organisms could be present in dirty water. Hence, it drives engineer to improve
water purification systems to filter out most microbes that could be harmful to our health [4].
Furthermore, engineers began to use chlorine as a disinfectant to reduce turbidity, and this effort
has successfully reduced the risk of contracting water-related diseases such as typhoid,
dysentery, or cholera. This process was later called chlorination; along with filtration, it has
become one of the most effective methods of water purification. However, it was not the end of
the engineering journey, because in the 1980s it was found that some chlorine-resistant
pathogens could exist in purified water. The pathogens were quite dangerous; they could cause
hepatitis, gastroenteritis, or cryptosporidiosis, which could greatly threaten human lives [2]. This
issue forces more engineers and scientist to devote their full attention to improving water
purification methods so that more bad chemicals can be removed from the water.
Implications for Health
Approximately 3.5 million people still succumb each year to diseases that are caused by drinking
contaminated water. Most of the time, approximately half of the world’s hospital beds are
occupied by people suffering from plagues that were the result of drinking dirty water. These
statistics indicate that the lack of access to clean drinking water is very severe in the world [5].
According to the National Academy of Sciences, illnesses that are caused by drinking dirty water
can be categorized into five types: waterborne, water-washed, water-based, water-related and
poor sanitation. However, only waterborne illnesses are associated with the danger of drinking
dirty water. As shown in Figure 2, waterborne diseases result from drinking water that carries
micro-parasites, bacteria and viruses that live in waste-contaminated water. Examples of the
diseases are typhoid, cholera, dysentery, hepatitis, and Giardia [5].
Figure 2. Waterborne disease. http://blog.ace4it.com/wp-content/uploads/2011/02/disease.png
The diseases usually come from bacteria that contaminate the water. The bacteria often originate
from human and animal wastes that go back into the water supply and contaminate the water [6].
Not only that, but there are also industrial and agricultural chemical wastes that could pollute the
water [7]. These chemicals are claimed to be very damaging to our bodies. The risks to human
have become more threatening than before because of the increase in agricultural and industrial
chemical uses. Once this polluted water reaches the consumers, it is too late to prevent them
from getting catastrophic diseases [8]. Therefore, an advanced water purification system is
needed to prevent this dirty water distribution problem from happening as we consume water on
a regular basis. Thus, purified water helps us to be more healthy and protected from all the
potential diseases.
Measuring the Quality of Drinking Water
In order to create an efficient water purification system, it is important to know the standards that
determine whether the water is safe to drink. Appraising the water quality is quite tricky. How
can we tell if any given water sample is hygienic? Is it the color or the odor? Yes, it is true that
color and odor are the most obvious ways to assess the quality of the water. Nonetheless,
scientists and engineers found that taste and odor are not the only parameters of safe drinking
water. Just because the water looks clear and tasteless does not mean there are no harmful
bacteria and chemicals that are not visible to the naked eye [9].
There are several factors that determine whether water is safe to drink, including pH level,
turbidity, odor, nutrients, total suspended solids (TSS), and hardness. PH is a scale ranging from
0 to 14 that measures how acidic or basic the water is. If the pH level is too far from 7 (neutral),
it indicates the possibility of there being some undesirable pollutants in the water that could be
threatening to human health. As shown in Figure 3, turbidity has been one of the most important
factors in determining water quality. If the water condition is muddy, it means that the turbidity
level is high. Thus, it implies that people who drink the water will be more likely to experience
gastrointestinal disease such as diarrhea. In addition, TSS are small solid materials that are
contained in the water. They usually consist of calcium, chlorides, nitrate and other ions particles
that are able to pass through the water filter. Higher concentrations of suspended solids can serve
as carriers of toxic chemicals. For instance, pesticides used on irrigated crops might get carried
away when the concentration of TTS is high, which could be dangerous when the water is
consumed by humans. Last but not least is the idea of hardness in water. If the water is hard, it
contains a substantial amount of calcium and magnesium, as well as a variety of other metals. As
water goes through rock and soil, it dissolves a minuscule amount of minerals and holds them in
solution. Hard water is safe to consume as long as the metal substances do not exceed 10% of the
whole water solution [10]. These parameters allow water suppliers to examine the drinking water
thoroughly so that the water passes the minimum standards for potable water, even if the water
quality is not perfect.
Figure 3. Turbidity. http://steinhardtapps.es.its.nyu.edu/nyuhudson/wp-content/uploads/2012/10/turbidity.jpg
Drinking Water Purification Process
To sanitize the water, several steps need to be taken. The water purification process is useful
because it may significantly decrease the number of particles including suspended solids,
parasites, microscopic organisms, algae, viruses, fungus and a range of dissolved and particulate
materials in the water [11]. There are several techniques for making potable water. Even though
in different places the water purification standards may vary, the necessary steps of purifying
water are still the same.
The most widely used water purification requires six fundamental steps. First, the water is taken
from a water source such as a well, river, lake, or reservoir. [12]. Then, coagulants like lime and
alum are added to the water. A coagulant is a magnet-like substance that causes particles inside
the water to cluster together. Once the particles are clustered together, they are called floc. Next,
the water is clumped and shaken together. After that, the water is left for 24 hours so that the
clumped materials can gravitate to the bottom of the water. This separation between floc and
water is called clarification. After that, the water is filtered so that the water can be entirely
separated to the floc. By this time, most harmful particles will have been discarded. However, we
still need to remove the residual tiny particles that are not able to be removed by filtration. The
water is then stored in a closed tank in order for it to be disinfected by both chlorine and ozone
so that most viruses, germs and fungus are eliminated. Then, the water is aerated because lack of
oxygen in water increases the relative population of microorganisms. Aeration is the process that
increases the oxygen saturation, so that the water carries more oxygen. Ultimately, the water is
channeled to households through pipes for distribution [13]. This method of water purification,
as shown in Figure 4, has been adopted in most places because of its effectiveness in treating
dirty water so that it becomes safe to drink.
Figure 4. Water purification process. https://www.ecwa.org/content/learningcenter/treatment.gifs
Future Developments
By using the current water purification method, we can arrive at water that is relatively safe to
drink. However, scientists and engineers are still trying to find better ways to improve this
technique, since there could still be a very tiny harmful particle that is very difficult to remove
using the current method. This results in more people expecting scientists and engineers to come
up with a new advanced way of purifying water. Although most water purification systems in the
U.S. are already sophisticated enough, there are still small fractions of people who do not have
access to clean water. One potential future water treatment was found by the Southern California
Institute of Architecture when they held a contest to select the best project for the 4-mile area
near the Los Angeles River and promised ten thousand dollars in prizes for winners. Project
Umbrella ended up winning the competition, it is mushroom-like structures named solar
evaporators that penetrate into the city's sewage, gathering and purifying the dirty water
originating from the surrounding neighborhoods. Through the process of evaporation and
condensation, clean water is allocated and released into the streets which reconstructs the
conventional streets into a network of lush and cultivated landscapes as shown in Figure 5 [14].
Figure 5. Project Umbrella. http://brentwoodlifestyle.losangelesrealestatevoice.com/2010/10/07/new-constructionseries-project-umbrella/
However, if we look to many developing countries such as countries in Africa or South East
Asia, the problem of dirty water is much worse. So we should not only care about developing the
United States’ water purification system, we could also help other developing countries to
revitalize their water treatment processes. The problem is that most developing countries do not
have tremendous resources like the United States has with the Project Umbrella so they might
not be able to create large-scale water purification processes which cost a lot of money.
Consequently, small-scale devices are being developed for developing countries where the
regular water purification system is not yet capable of generating clean water. The device is a
lifestraw, which is a tube that can be used to purify the unclean water and make it safe to drink,
as shown in Figure 6. This straw can greatly reduce the chance of people contracting familiar
water-related diseases such as typhoid, cholera, and diarrhea. Also, this device is not expensive,
so that it is possible for destitute families to afford it and use it on a daily basis [15].
Figure 6. Lifestraw. http://inhabitat.com/6-water-purifying-devices-for-clean-drinking-water-in-the-developingworld/
The lifestraw example indicates that we do not have to invent an expensive, huge, or futuristic
water purification process. A simple tool that can make other lives easier is enough for the future
development of water purification. Now, it becomes a challenge for engineers to come up with
better and cleverer methods of purifying water that could decrease the number of casualties due
to drinking dirty water.
References:
[1] C. Binns et al (2013, November). How Long Can a Person Survive Without Water? [Online].
Available: http://www.livescience.com/32320-how-long-can-a-person-survive-withoutwater.html
[2] The History of Drinking Water Treatment [Online]. Available:
http://www.epa.gov/safewater/consumer/pdf/hist.pdf
[3] Water Quality – Turbidity [Online]. Available: http://www2.vernier.com/sample_labs/ESV12-COMP-water_quality_turbidity.pdf
[4] E. R. Tufte, “John Snow and the Cholera Epidemic,” in Visual and Statistical Thinking:
Displays of Evidence for Making Decisions, 5th ed. Cheshire, CT: Graphics Press LLC,
1997, pp. 5-16.
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m
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[9] Is it Safe to Drink? [Online]. Available:
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[10] Measurement of Water Quality [Online]. Available:
https://wiki.engr.illinois.edu/download/attachments/31394596/Week5.pdf?version=1
[11] Decontamination: What Exactly is Decontamination [Online]. Available:
http://mantisenvironmental.com/decontamination/
[12] Where Does Our Household Water Come From? [Online]. Available:
http://water.usgs.gov/edu/qa-home-wherefrom.html
[13] Water Treatment Process [Online]. Available:
http://water.epa.gov/learn/kids/drinkingwater/watertreatmentprocess.cfm
[14] F.R. Smith. Community Watch… Project Umbrella [Online]. Available:
http://brentwoodlifestyle.losangelesrealestatevoice.com/2010/10/07/new-constructionseries-project-umbrella/
[15] 6 Water-purifying Devices for Clean Drinking Water in the Developing World [Online].
Available: http://inhabitat.com/6-water-purifying-devices-for-clean-drinking-water-inthe-developing-world/