Session A9
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Disclaimer — This paper partially fulfills a writing requirement for first year (freshman) engineering students at the University
of Pittsburgh Swanson School of Engineering. This paper is a student, not a professional, paper. This paper is based on
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FROM WASTE TO FUEL: ANAEROBIC DIGESTION IN WATER
TREATMENT
Tristan Witek, [email protected], Vidic, 2:00, Emma Minck, [email protected], Sanchez, 5:00
Abstract - Systems of pipes to transport water have been used
throughout human history; from Roman aqueducts carrying
drinking water to the indoor plumbing implemented in nearly
every home today. At modern wastewater treatment centers,
the waste is set through three processes to remove suspended
solids, biodegradable organics, pathogenic bacteria, and
nutrients. The primary steps involve simple filtration methods,
but the final steps involve chemical disinfection with chlorine,
which can leave chemical residue that builds up, causing
more damage to the water in the long term. Chlorination must
be properly controlled or it leaves behind an odd taste and
odor and results in the turbid waters becoming more
susceptible to bacterial infection. However, after many
expensive, potentially dangerous years of chemically treating
our waste, a safer and cheaper method has arisen: anaerobic
digestion. Anaerobic digestion is a life process performed by
one genus of bacteria that requires no oxygen and, in the end,
produces methane, which can be burned for energy. This
paper will fully address the process of anaerobic digestion
and how it can be entirely implemented into sewage systems
and wastewater treatment centers to ensure cleaner, safer
water as well as supply an efficient amount of energy. This
technology ensures a cost-effective method of purifying the
very thing civilizations survive on and can reduce the spread
of disease. If anaerobic digestion is used in the treatment
process, and perhaps even directly embedded into the
materials used in treatment facilities, the problems
surrounding both clean water and energy renewal can be
properly addressed.
Key Words – Anaerobic digestion, Aqueduct, Chlorination,
Methane, Pathogenic bacteria, Protozoa, Wastewater
treatment center
WHERE IT ALL STARTS
The History Behind Water Treatment
It’s no secret that water is essential for all forms of life. It
is present in the air, the ground, food, animals, and humans.
Ancient civilizations began around sources of water, such as
Egypt along the Nile or Mesopotamians along the Tigris and
Euphrates. When empires began to spread, people were faced
University of Pittsburgh Swanson School of Engineering 1
31.03.2017
with the issue of transporting water from rivers, lakes, and
oceans to their newly established cities. The Romans
constructed aqueducts to do the job, using gravity to bring in
water from distant sources to fully supply their houses,
fountains, baths, and latrines.
Current Water Treatment Methods
Later societies only expanded on the idea of aqueducts,
developing sewer systems to help direct wastewater away
from the residential areas and reduce the spread of disease,
ensuring a cleaner environment. Wastewater treatment
centers to help recycle water, instead of simply dumping the
contaminated liquids, were constructed, and tend to follow
three overall processes: primary, secondary, and tertiary,
illustrated in Figure 1.
FIGURE 1 [1]
Main process of initial wastewater treatment
The primary treatment acts as an initial filter to remove
larger suspended solids. Secondary treatment removes
dissolved organic matter with the use of microbes and settling
tanks. Any additional impurities that make it past the tertiary
treatment are disinfected chemically with chlorine [1].
Some of this treated water leaves the center and is returned
as surface and ground water. Some of this is recycled as
sewage or industrial water once more. Some of it, however, is
Emma Minck
Tristan Witek
treated again to be used as drinking water, as Figure 2
demonstrates.
Pittsburgh, Pennsylvania
Early February 2017, a boil water advisory was sent out
across Pittsburgh, Pennsylvania. The issue arose due to the
detection of low chlorine levels, meaning the water was likely
not fully cleaned in the wastewater filtration process.
Although the advisory only lasted a few days, it certainly
rattled the nerves of residents. The ingestion of the water
without boiling during this period resulted in nausea,
headaches, fever, diarrhea, and vomiting. Had this continued
longer, infections and long-lasting bacterial diseases would
have occurred [3].
Chapel Hill, North Carolina
FIGURE 2 [2]
Treatment process of turning wastewater to drinking
water
Around the same time as the Pittsburgh case, another case
arose further down the east coast in Chapel Hill, North
Carolina. The Orange Water and Sewer Authority issued their
own boil water advisory alert when a water main broke. The
damage resulted in a pressure build up in the water flow. The
still water caused an accelerated growth of disease-causing
bacteria. Schools, restaurants, and businesses all shut down
and eventually any use of water was prohibited, boiled or not.
This disrupted daily behavior and sent shockwaves through
citizens and government officials alike for several weeks [3].
While this case does not revolve solely around the
chlorination process, it shows a need for improvement in the
transportation of waste and drinking water. The structure of
the wastewater treatment centers and their connecting
pipelines are causing as many problems as the treatment itself
is.
This treatment follows a similar systematic process. The
water is first chemically treated through coagulation and
flocculation, two reactions that binds particles together to
enlarge them. The water goes through sedimentation next,
allowing the large particles to settle at the bottom of the tanks.
Next it is filtered in a manner similar to the primary treatment
of wastewater. The final step is disinfection, which is done so
chemically through the use of chlorine as well [2].
The majority of problems occur at the end of each of these
process, through the act of chlorination. While chlorination is
one of the most common methods of disinfection, it can be
dangerous when gone unmonitored. If too little chlorine is
added, not all bacteria will be killed and the water returns still
contaminated. If too much is added the chlorine leaves behind
residue that will build up over time and contaminate the very
water it was meant to clean. The result of either case tends to
be an increase in disease-causing bacterium such as E-Coli
and coliform. Chlorine can also increase general illnesses,
especially in young children and the elderly [3]. The U.S.
Council of Environmental Quality even claims that those who
drink chlorinated water have a cancer risk “as much as 93
percent higher than among those whose water does not
contain chlorine,” [4]. The impact of this chemical process is
clear and devastating, especially in the long term.
Flint, Michigan
One of the largest modern cases of water contamination in
the United States arose in Flint, Michigan in April of 2014.
The first of many boil water advisories occurred when fecal
coliform bacterium was detected in the water. In response to
this advisory, the city decided to flush the system and increase
the amount of chlorine in the water. This became a constant
pattern over the years. Boil water advisories would call for
more chlorine in the water which would build up and result in
another advisory, continuing in a positive feedback loop of
contaminated water.
The result was an increase in odd illnesses, particularly in
children, and nearly unusable water across the city. The issue
continues to this day with more than 17,000 residents filing a
$722 million class action lawsuit against the EPA [3].
CURRENT WATER ADVISORIES IN THE
U.S.
This contamination is appearing in cities across the
country, raising a few questions about the state of wastewater
treatment centers in the United States in terms of both the
cleaning processes and the structures themselves. The
following cases illustrate the issues with the modern way of
disinfecting waste and drinking water.
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Emma Minck
Tristan Witek
bacteria can then move on to the next step, acidogenesis. In
acidogenesis, the bacteria take the compounds from the first
step and digest them again, this time returning ammonia,
volatile fatty acids, and alcohols. The third step, acetogenesis,
draws from the compounds of both hydrolysis and
acidogenesis to form acetic acid, hydrogen, and carbon
dioxide. With these three compounds now in the mixture, the
bacteria are ready to finish their digestion. Finally, in
methanogenesis, the bacteria process the acetic acid,
hydrogen, and carbon dioxide to produce methane gas, and
more carbon dioxide. The entire process is illustrated in
Figure 3.
ANAEROBIC DIGESTION: AN ORGANIC
WAY TO CLEAN
With so many issues plaguing America’s current water
treatment systems, an alternative method would benefit the
country. As such, following Europe’s lead would be the best
course of action, as they have implemented an effective
technology called anaerobic digestion. Anaerobic digestion
itself involves certain bacteria, known as anaerobic bacteria,
and the way they respire. Thus, as anaerobic digestion occurs
naturally, the real technology comes from how to actually
take advantage of anaerobic digestion [5].
However, such a technology would require special
conditions and as such, would require special treatment
facilities. Thus, implementing this technology would require
reworking current water treatment plants to comply with these
conditions. Nevertheless, adapting the plants for anaerobic
digestion would make them less complex, taking up fewer
resources and space.
FIGURE 3 [5]
Flow chart describing the process of anaerobic digestion
Bacterial Life Processes
All life on the planet has evolved to interact with and
benefit from other species. This simple observation explains
why treating water with bacteria benefits humans. Everything
starts with the nitrogen cycle, something that all organisms
experience and contribute to. To understand the workings of
the nitrogen cycle, consider a deer.
The deer, an herbivore, eats plants to sustain itself. In doing
so, organic matter travels through the deer, and eventually
back to the ground in the form of feces. Various species of
bacteria then break down the organic matter to keep
themselves alive, rearrange the compounds in the feces, and
turn some of those compounds into gases in the process. The
same bacterial process happens to the deer itself once it dies;
again, bacteria consume the organic matter the deer leaves
behind. This cycle goes on and on, recycling and repurposing
the nitrogen and carbon in all living beings.
Anaerobic digestion works by taking advantage of this
natural cycle. Seeing as human feces are organic matter just
as deer feces, bacteria will consume and repurpose human
feces just the same. However, anaerobic digestion is slightly
different from the regular decomposition of organic matter. In
the deer example, regular bacterial digestion was described,
not anaerobic digestion. Anaerobic digestion is the same thing,
except that it uses a genus of bacteria called anaerobic bacteria,
and of course the word anaerobic, which means “requiring an
absence of free oxygen.” In other words, anaerobic digestion
only happens in environments devoid of gaseous oxygen,
making a closed container of sewage the perfect environment
for these bacteria to perform their life processes [5].
Once in this environment, the bacteria start with hydrolysis,
the process of breaking down the non-soluble proteins,
carbohydrates, and lipids that make up the fecal matter. Once
these are broken into amino acids, sugars, and fatty acids, the
The methane and carbon dioxide, both being gases, bubble
out of the solution, forming an atmosphere of organic gases
overhead. Thus, on an elemental level, everything that once
was a part of the fecal matter either became gas and removed
itself from the former wastewater, or stayed behind to keep
the bacteria alive, allowing the same bacteria to continue
digesting other organic matter in the wastewater [6].
Necessary Design Upgrades
Unfortunately, the vast majority of current wastewater
treatment plants in the United States could not support a
simple change of method. For those plants that cannot be
converted, a total overhaul of the current design is required.
This situation accounts for about 11,800 treatment plants in
the US. The main reason these plants cannot receive direct
upgrades is their pipe and tank layout. Figure 4 represents a
simplified version of current wastewater treatment plants, and
illustrates these discrepancies.
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Emma Minck
Tristan Witek
have. As a result, current plants’ pipe systems would have to
be reworked, branched off, and equipped with degasifier
technology to make an anaerobic digester work.
Implementing these changes on the existing structure shown
in figure 3 would be awkward, time consuming, and a waste
of both space and money.
Since direct upgrades are infeasible, the only other option
is to replace the cleansing tanks and piping systems. Once
those have been taken apart, the facilities that would take their
place would only use a fraction of the original land, as Amit
Dhir notes, “the other major advantage of UASB [an
anaerobic digester] is its low land requirement” [8]. So, when
anaerobic digesters are built from the ground up, they not only
take less space than current treatment systems, but also take
significantly less space than the result of trying to directly
upgrade current plants. Having discussed how anaerobic
digestion technology works, one can make a more properly
educated decision on the benefits and drawbacks of using this
technology.
FIGURE 4 [2]
Common layout of a current wastewater treatment plant
When looking at figure three, one can easily see that the
treatment tanks have open tops. This already poses a
compatibility problem with using anaerobic digestion, as the
oxygen in the atmosphere would interfere with the bacterial
process. Theoretically, such a problem would disappear if one
simply put a lid on each open tank. While this fix would allow
anaerobic digestion to occur, it trivializes the largest benefit
anaerobic digestion has to offer; methane gas collection. An
anaerobic digestion tank needs to have a piping system that
allows it to collect the methane, and to resend the wastewater
through the system, as shown in Figure 5 [7].
ADVANTAGES AND DISADVANTAGES
As with any process, anaerobic digestion has its own
advantages and disadvantages. While current disinfection
methods are completely chemical, the anaerobic process is not.
It occurs naturally throughout life and in the nitrogen cycle as
shown in the illustration of the deer. It follows the steps
current water treatment centers do, breaking down large
particles from things like proteins and carbohydrates into
amino acids and sugars [6]. They are continuously digested
until the bacteria has converted the fecal matter in gases such
as Carbon Dioxide (CO2) and Methane. Anything left over
does not contaminate the way excess chlorine does. Instead,
it fuels the bacteria to repeat the process again [5].
In addition, anaerobic digestion does not have to be as
closely monitored. Too much or too little chlorine can be
devastating, but this digestion occurs naturally and is
monitored solely by the bacteria completing the task. Extra
waste is converted to gas or simply used in the process again.
The methane gas produced can even be used as a source of
renewable energy, unlike anything produced or removed in
current water treatment processes [4].
Anaerobic digestion, however, is not perfect. One of the
major issues comes with the physical construction of the
anaerobic digesters, since they are still relatively new and not
widely used. Many treatment centers would need to be
entirely reconstructed, would could be costly as well as time
consuming. The process may also result in odors if there is a
high number of methanogens present. There is some
monitoring needed in this process as well in the temperature
and pH level, though not nearly as much as chlorine [5].
Overall, the advantages of anaerobic digestion
demonstrate a significant improvement when compared to
current chemical processes. The disadvantages are
FIGURE 5 [7]
Basic layout of an anaerobic digester
By using a simple valve leading to a pipe in the top of the
container, the plant operator can allow the methane to escape,
where it would flow through the pipe and into holding tanks.
This use of the new plant’s design allows for very efficient
collection of methane, a flammable natural gas that can be
burned for energy. However, it is important to note that not
all methane produced would evaporate and be collected. Due
to the equilibrium between the gaseous and dissolved forms
of methane, roughly 15% of the produced methane will stay
dissolved in the wastewater. Since leaving this excess
methane in the water would clearly be harmful, another part
of the system, called a degasifier, extracts it. The valve is a
simple enough addition, but the degasifier requires special
piping that many current wastewater treatment plants do not
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Emma Minck
Tristan Witek
unavoidable, as with anything, but they will not result in the
same long term damages chlorine does.
which burdens them with the cost. Therefore, by spreading
out the cost of upgrading such that only a few hundred plants
receive upgrades each year, the original price tag becomes
much more manageable. And, as time progresses, the
technology’s installation price will decrease, making it more
and more affordable as it becomes more available [7].
In addition to spreading out the cost, another way to make
this technology work economically lies within the very
purpose of using it. Anaerobic digesters cost significantly less
to maintain than do their current counterparts: current plants
cost around $333,000 to maintain per year, whereas anaerobic
digesters cost a mere $11,000-$51,000 per year. Just on
upkeep alone, a brand new anaerobic digester would pay for
itself in three and a half years. For a plant that received direct
upgrades, that figure falls just under two years. Factoring in
the revenue from any energy the plant decides to sell, these
plants can easily pay for themselves in a little over a year of
operating [8].
The American government stands as the last major
obstacle for implementing anaerobic digestion in wastewater
treatment plants. The Department of Homeland Security
(DHS) notes that around 16,000 treatment facilities are
publicly owned. This would not be a problem, assuming that
the government funds wastewater treatment well enough to
cover the costs. However, trends found by the University of
North Carolina at Chapel Hill have found that government
spending on wastewater management has been trending
downwards since 2010 [3].
That same study also noted that the federal government
only accounts for 4 billion dollars of spending, out of over one
hundred billion dollars of spending overall. The other 96% of
spending comes from state and local governments, where
spending can vary wildly across different states. Looking at
Figure 6, one can see that federal spending has stayed fairly
stagnate for the past two decades. Due to inflation, this is
tantamount to the federal government spending less on
wastewater treatment each year [9].
IMPLEMENTATION IN THE US
After seeing the advantages outweigh the disadvantages so
heavily, one may ask why the US shies away from using
anaerobic digestion for water treatment. Aside from the
apparent unease in abandoning familiar methods,
implementing this new technology in the United States would
take considerable effort.
Since only 1,200 of the nation’s 17,000 water treatment
plants currently use anaerobic digestion, that leaves a
substantial 15,800 plants to convert over to anaerobic
digestion. However, when discussing what the new plants
would look like, it was mentioned that only 11,800 plants
would require a complete overhaul. This discrepancy arises
because of those 15,800 that do not use anaerobic digestion,
about 4,000 of them can receive direct upgrades to their
existing facilities and buildings. That 25% significantly
facilitates the process of implementing these new plants in the
United States, as it would take less time, and less money [7].
In theory, these upgrades should be simple enough, but
putting new technology into practice always has different
impacts and unforeseen issues. Thus, it would be important to
proceed cautiously if this were the first time that such a
technology was introduced to the world. Luckily, this is not
the first time. Many European countries have already invested
in anaerobic digestion, with great success; the water in Europe
remains safe, and they even produce energy from the process.
With an already successful example in the world, America
can follow in their footsteps.
Economic Requirements and Feasibility of
Implementation in the US
Having already discussed the physical replacement of
water treatment plants previously, the cost of the upgrades
constitutes the largest challenge. In Whitewater, Wisconsin,
the city government released a report on a study of wastewater
treatment using anaerobic digestion. They explored many
different alternatives before concluding that anaerobic
digestion was the best option, and went on to project costs for
the project. They projected that the technology and equipment
needed for anaerobic digestion would cost $444,000, and that
the cost for a new plant, with the cost of technology included,
would be $976,000. Compared to current, typical wastewater
treatment systems, costing around $500,000-$1,000,000,
anaerobic digestion clearly falls within the price range of
using the old methods. However, when considering how
many plants there are to upgrade, the cost ends up being
around 17 billion dollars, even with the 4,000 direct upgrades.
For an individual company, such a cost would be near
impossible to handle. While there are a few privately-owned
water treatment plants, most are owned by the government,
FIGURE 6 [9]
Federal (red) and State (blue) government spending on
water and wastewater utilities
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Emma Minck
Tristan Witek
producing less pollutants than other fuel sources. While the
United States does not have as severe air pollution problems
like those in China or India, where the public faced beyond
dangerous levels of air pollution indoors, US cities still face
dangerous levels of pollutants in the air. The vast majority of
this pollution stems from the multitude of automobiles and the
presence of power plants and other industrial buildings.
Focusing on the power plants, using the methane produced
from anaerobic digestion could reduce the dependence on
power plant driven electricity. Using natural gas instead of
other fuels like coal or gasoline for power would drastically
reduce pollutants in the air [10].
Another consequence of using natural gas instead of coal
or oil lies in the collection of the fuel source. Eventually, oil
and coal deposits will run out, as these are non-renewable
energy sources. Before the use of anaerobic digestion, natural
gas was also a non-renewable source of energy. However,
natural gas could easily be replenished by using anaerobic
digestion to simply produce more of it whenever a city treats
its wastewater One batch of wastewater, according to T.Z.D.
et al, produces an average of about 1,200 cubic meters of
methane [5]. Also, because the use of natural gas would lead
to less use of oil and coal, there would be less incentive for
companies to use the controversial technique “fracking.”
Overall, while natural gas is not perfect for the environment,
compared to current usage of fossil fuels, the methane from
anaerobic digestion would be very beneficial to the
environment.
That fact, coupled with likely upcoming budget cuts due
to an increase in military spending, will deplete federal
spending on water infrastructure. However, it is likely that in
response to this, the states will increase their own spending to
make up for the deficit, as they did in 1986 when the federal
government originally cut their spending. Although this
would put excess strain on state governments, the amount of
overall funding should stay the same, allowing technology
like anaerobic digestion a chance at being funded. While
upgrading to anaerobic digestion in the United States would
be costly and time consuming, with proper support from
either the federal or local government, these upgrades are
feasible.
THE SUSTAINABILITY OF ANAEROBIC
DIGESTION
Beyond whether or not implementing a technology is
feasible lies the question, “Should this be used?” By
considering all the advantages and disadvantages discussed
earlier, it is possible to look to the future and predict with
decent accuracy the consequences of implementing anaerobic
digestion in wastewater treatment centers. This technology
especially affects the environment, and the lives of the
citizens it would serve.
Environmental Impacts
Social Impacts
The first notable impact involves the methane produced by
anaerobic digestion. Collecting the methane, regardless of
energy purposes, is important because methane acts as a
greenhouse gas, 20 times more potent than carbon dioxide at
trapping heat. If these new digesters simply allowed the
methane to escape, the added methane would contribute to
global warming exponentially compared to carbon dioxide. In
addition to keeping the methane out of the atmosphere, using
that methane as fuel can also lead to less carbon dioxide in the
atmosphere. The US Energy Information Association (EIA)
states that “burning natural gas [methane] for energy results
in fewer emissions of nearly all types of air pollutants and
carbon dioxide per unit of heat produced than coal or refined
petroleum products” [8]. In fact, burning methane produces
about 117 pounds of carbon dioxide per million British
thermal units (btu) of heat produced, whereas sources like
coal produce more than 200 pounds of carbon dioxide per the
same amount of btu. So, while burning methane still
contributes negatively to air pollution and greenhouse gases,
it contributes at a rate far less than that of other traditional
energy sources. This could lead to a decrease in the
dependence on fossil fuels, thereby reducing the harmful
effects humans have on the atmosphere.
In addition to fighting global warming, using methane as a
fuel helps make the air the public breathes cleaner by
The other major impact involves the citizens of the United
States. If anaerobic digestion were to be implemented, the
main benefit would come in the form of a couple of major
health benefits for citizens.
The first major health benefit ties to the simple concept of
clean, and available, drinking water. For example, California
had been experiencing a state of almost constant drought for
five years. Since there was not as much rainfall as usual, it
would be beneficial for Californians to have been able to reuse
any water possible, something that can be done using
anaerobic digestion. The digestion process cleans the water
well enough that humans can drink it with no health issues or
concerns, an inevitable future according to the Anas
Ghadouani of the University of Western Australia. So,
Californians could recycle their wastewater and use it to do
anything from shower to cook to water plants, if they had
anaerobic digesters for treating wastewater. Another example
of this benefit is avoiding water crises. If water treatment
facilities in say, Flint, Michigan had been upgraded, the entire
crisis could have been avoided, and the thousands of affected
citizens would likely have been safe. A crisis like that could
easily happen again, as history repeats itself, but having these
upgrades could help ward off these disasters [10].
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Tristan Witek
The next health benefit comes from the reduced air
pollution. It is well known that pollutants in the air can
damage lungs, eyes, and nostrils, and even potentially cause
cancer or blindness. Therefore, lowering pollutant levels
would be in the interest of public health. As was noted before,
anaerobic digestion does indirectly lower pollutants in the air
by using a cleaner energy source. Once again, public health
would benefit from the implementation of anaerobic digestion,
this time thanks to better quality of air to breathe [6].
Another benefit to society would fall to those who happen
to live near wastewater treatment facilities. Houses built
around such facilities usually sell for much less than houses
built elsewhere, for one distinct reason: the smell. Because of
the open top treatment tanks, the smell of sewage wafts
through the air around a neighborhood, creating a zone of foul
smelling atmosphere. On the other hand, an anaerobic
digester has a closed top, and all gases are contained within
the system, never released to the open air. As a result, those
who live near water treatment plants would not be constantly
bombarded by foul odors. While this is not a major victory,
it’s a change that many citizens would appreciate [10].
The use of anaerobic digestion clearly has an enormous,
positive impact on the community, both environmentally and
socially. The entire process filters and cleans water in a
manner current wastewater treatments cannot accomplish
without some level of contamination. Present chemical
treatment is rather dangerous and tends to cause more long
term problems that outweigh the immediate satisfaction of
supposedly clean water. Anaerobic digestion is a process that
cuts down on the toxicity of wastewater and purifies the very
thing that civilizations live and thrive on.
1.8.2017.http://water.worldbank.org/shw-resourceguide/infrastructure/menu-technical-options/wastewatertreatment
[3] CNN Wire Service. “Flint Water Crisis Fast Facts.” Fox
News
6.
2.2.2017.
Accessed
2.10.2017.
http://fox6now.com/2017/02/02/flint-water-crisis-fast-facts/
[4] N. Hearn. “Chlorine in Drinking Water.” Accessed 3.25.
2017.http://www.waterbenefitshealth.com/chlorine-indrinking-water.html
[5] T.Z.D., A.J.M, J Stams, G. Zeeman. “Methane production
by anaerobic digestion of wastewater and solid wastes.”
Accessed
1.4.2017.
hhttps://www.researchgate.net/profile/Marcel_Janssen/publi
cation/40129041_Bio-methane_Biohydrogen_Status_and_perspectives_of_biological_methane_
and_hydrogen_production/links/5419520a0cf203f155add97
6.pdf#page=59
[6] M. Lono-Batura, Y. Qi, N. Beecher. “Biogas Production
and Potential from U.S. Wastewater Treatment.” Biocycle.
Published
12.2012.
Accessed
1.25.2017.
https://www.biocycle.net/2012/12/18/biogas-productionand-potential-from-u-s-wastewater-treatment/
[7] “Sewer System Design.” LDC The Civil Engineering
Group.
Accessed
1.8.2017.http://www.ldccorp.com/services/civilengineering/sewer-system-design.html
[8] A. Dhir, C. Ram. “Design of an Anaerobic Digester for
Wastewater Treatment.” International Journal of Advanced
Research in Engineering and Applied Sciences. 11.2012.
Accessed
2.8.2017.
http://garph.co.uk/IJAREAS/Nov2012/6.pdf
[9] “Ohio City Anaerobic Digestion Upgrade to Harness
Wastewater for Renewable Energy.” 1.20.2014. Accessed
2.8.2017. http://www.waterworld.com/articles/2014/01/ohiowastewater-treatment-plant-upgrades-anaerobicdigestion.html
[10] Center for Sustainable Systems, University of
Michigan. “U.S. Wastewater Treatment Factsheet.”
University of Michigan. Published 8.2016. Accessed
1.25.2017.
http://css.snre.umich.edu/sites/default/files/U.S._Wastewater
_Treatment_Factsheet_CSS04-14.pdf
FINAL ANALYSIS
After reviewing all the facts put forth in this paper and
weighing the different importance’s between them, the final
answer is no surprise. The constant failings of water treatment
facilities across the nation illustrate the need for a change.
With anaerobic digestion as an option, and seeing that it offers
far more benefits than it does drawbacks, it makes sense that
anaerobic digestion would be a good choice. When applying
these advantages and disadvantages to the real world, the
benefits that arise from using anaerobic digestion are
numerous and meaningful to the nation’s environment,
economy, and citizens. In conclusion, as an alternative to
current water treatment methods, anaerobic digestion cleans
just as well, works more efficiently cost-wise, and results in
better outcomes for the country.
ADDITIONAL SOURCES
J. Kemsley. “Using Bacteria to Clean Water.” 8.29.2011.
Accessed 1.8.2017. http://pubs.acs.org/doi/pdf/10.1021/cenv089n035.p034
“Types of Bacteria Used in Wastewater Treatment.”
Operation Matters. Published 6.2012. Accessed 1.25.2017.
https://kyocp.wordpress.com/2012/06/14/types-of-bacteriaused-in-wastewater-treatment/
Z. Xia. “Biomimetic Principles and Design of Advanced
Engineering
Materials.”
7.19.2017.
Accessed
SOURCES
[1] “Design of Sewer System.” Accessed 1.8.2017.
http://civilengineerspk.com/design-of-sewer-system/
[2]
“Introduction
to
Wastewater
Treatment
Processes.”
Accessed
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Emma Minck
Tristan Witek
1.8.2017.https://books.google.com/books?id=8udODAAAQ
BAJ&pg=PA151&lpg=PA151&dq=could+bacteria+be+pur
posefully+embedded+in+certain+materials&source=bl&ots
=lJM-pAz73F&sig=cleTrFLWMA-LQnLPnwNvtdRYTQ&hl=en&sa=X&ved=0ahUKEwiPotWntrjRAhVIbi
YKHW2NCAcQ6AEIJjAC#v=onepage&q&f=true
ACKNOWLEDGMENTS
We would like to acknowledge our roommates’ inputs and
assistance in some peer editing of our paper, as well as our
co-chair who provided immense guidance through her past
work.
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