1. UNIVERSITY OF WISCONSIN
Desalination
An investigation into desalination, its brine
waste, and ways to mitigate its impact.
Kevin M. Gildea
5/10/2012
Department of Geological Engineering

2. 2
Table of Contents:
1) Executive Summary Page 3
2) Introduction Page 4
3) Technical Background
a) Abundance Page 4
b) Water Quality Criteria Page 5
c) Direct Comparison of MSF vs. RO Page 5
d) Reverse Osmosis Page 6
e) Multi-Stage Flash Page 7
f) The Brine Waste Page 9
4) Environmental Impacts
a) Alteration of Ecosystems Page 10
b) Elevated Rates of Coastal Erosion Page 10
c) Salinated Inland Water Wells Page 11
5) Potential Solutions
a) Precipitation of Silver Chloride Page 12
b) Electrolysis of Aqueous Sodium Chloride Page 13
6) Recommendation Page 14
7) Conclusion Page 14
8) References Page 15
9) Appendix Page 16

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1) Executive Summary:
One-third of the world’s 7 billion people are living in regions of water scarcity (NAE,
2008) yet less than 1% of the water on Earth is directly available for human use (USGS, 2012).
In order to satisfy the water demands of everyone, the water beyond this 1% must be used as
well. Desalination is the main way to use saltwater or brackish water and can be done in many
different ways. The first way involves thermal energy and heating the saltwater until freshwater
begins to evaporate. The second way involves energy to pressurize the saltwater so that it passes
through a membrane. As the water passes through the membrane, the salt is extracted. Reverse
Osmosis is the most popular by such a wide margin that it is not worth considering other
membrane processes in this paper. There are key differences between thermal and membrane
processes when it comes to such factors as energy consumption and the nature of the bi-products.
Thermal desalination requires anywhere from three times to nine times as much energy as
membrane desalination (Lattemann and Hopner, 2008). This leads to a large carbon footprint
and an increasing popularity of thermal processes in areas where fossil fuels are abundant and
cheap, such as the Arabian Gulf (Macedonio, et al., 2012). Membrane desalination requires a lot
of pre-treatment chemicals to prevent compounds from forming on the membrane, which is a
phenomenon known as scaling (Sadhwani, et al., 2005). It also requires chemicals to prevent the
water from foaming up due to the pressure. A problem common to both processes is the
concentrated brine waste that is often discharged directly back into the near-shore marine
ecosystem.
Desalination is the answer to the water shortages of the future but the environmental
impacts associated with its brine waste must be addressed before it starts causing long term
damage to the world’s near-shore marine ecosystems. Extracting chlorine from the brine waste
is a priority because toxic levels have been found in discharge sites and have led to declining
populations of three types of algae (Sadhwani, et al., 2005). These algae are responsible for
sediment stability and preventing erosion. Other environmental impacts could be salinated
groundwater wells and the alteration of near-shore marine ecosystems.
Precipitation and electrolysis techniques are the focuses in this paper to extract key
chemicals. A precipitation reaction producing silver chloride and the electrolysis of aqueous
sodium chloride are both processes that create useful bi-products. The paper concluded that the
electrolysis of sodium chloride is the best choice because it could produce chlorine and hydrogen
gas that could be sold (Ganesh, 2001). The profit generated by the sale of the gas could go
towards research to develop machines that could run on hydrogen. This reaction would decrease
the chlorine concentration in the brine waste and decrease the fossil fuel consumption.

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2) Introduction:
Providing access to clean water is one of the 14 grand challenges for engineering put
forth by the National Association of Engineers (NAE, 2008). That is no surprise considering
there are 3.3 million deaths reported per year related to water quality and one-third of the world’s
7 billion people are living in countries plagued by water scarcity (Macedonio, et al., 2012).
However, only 3% of the Earth’s water is freshwater and 68.6% of this freshwater is locked in
the polar ice caps (United States Geological Survey, 2010). In response to the lack of
groundwater and surface water but abundant supply of seawater, desalination has become a
growing technology that is required in many arid, coastal regions around the world to produce
the potable and agricultural water necessary to sustain human life. Water is desalinated either by
intense heat or by passing through a membrane and this paper will explain both processes in
great detail.
A problem common to all desalination plants is the highly concentrated brine waste,
which is commonly fed back into the near-shore marine environment. Continual dumping can
have long term effects such as elevated rates of coastal erosion, altered marine ecosystems, and
salinated inland water wells. This paper will explain the adverse environmental effects in greater
detail and why it is important to lower the concentration of certain chemicals in the brine waste.
As potential solutions, this paper will investigate precipitating silver chloride out of the brine and
undergoing an electrolysis reaction involving the aqueous sodium chloride. Each solution is
based on how useful its by-products are and whether or not it is economically justifiable. An
investigation has concluded that the electrolysis of aqueous sodium chloride is an option that
should be further researched.
3) TechnicalBackground
a) Abundance:
According to the International Desalination Agency (IDA), there are currently 15,988
plants worldwide producing over 66 million cubic meters of water per day. Production increased
11.02% from 2009 to 2011 according to calculations using data from the IDA’s 2009 and 2011
reports. More plants with a production capacity of 11 million cubic meters per day are either
under construction or are contracted (IDA, 2011). Desalination can occur by thermal means or
by passing through a membrane, which account for 35% and 65%, respectively, of plants
worldwide. The predominating thermal and membrane technologies are multi-stage flash (MSF)
and reverse osmosis (RO), respectively. This paper will explain MSF and RO in great detail in
the following sections. Figure 1 shows the market share of the two compared to other processes:

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The MarketShare of EachDesalinationProcess
Figure 1: A figure displaying the relative abundance of each desalination process. RO=Reverse
Osmosis (membrane), MSF=Multi-Stage Flash (thermal), MED=Multi-Effect Distillation,
(thermal), ED=Electrodialysis (membrane) Reference: (Henthorne, 2012)
b) Water Quality Criteria:
This paper uses the term parts per million (ppm) frequently. Water is categorized
according to the ppm of various elements and compounds. Potable water must have the total
dissolved solids be less than 500 ppm (EPA, 2009). Less strict regulations apply for water
going toward agricultural use. Average seawater is approximately 35,000 ppm, and the
elemental breakdown is shown in Table 2 on Page 6.
c) Direct Comparison of MSF and RO:
Water is desalinated either by intense heat or by passing through a membrane. Table 1
outlines the key aspects of each process. Overall, thermal processes can handle more
concentrated solutions but do so at a much higher energy cost. Reverse osmosis can have a
higher recovery factor but that might be partly due to the lower raw water ppm. When it comes
to the price per cubic meter, reverse osmosis is about half the price as any thermal process.
Reverse osmosis is clearly more practical for brackish water applications. Brackish water is

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found in the groundwater inland in states that boarder the coast and is a mix between freshwater
and saltwater.
A Direct Comparison of Membrane vs. Thermal Technology
Thermal desalination processes (MSF,
MED, VC)
Membrane desalination processes (RO)
Typical salt content of raw water=30,000–
100,000 ppm
Typical salt content of raw water = 1,000–45,000
ppm
Desalted water with low total dissolved
solids concentrations (10–20 ppm)
Desalted water with total dissolved solids
concentrations between 100 and 550 ppm
Thermal energy consumption = 12
kWh/m3 (data for MSF)
Thermal energy consumption = 0
Energy consumption (MSF) = 17–18
kWh/m3
Energy consumption = 2.2–6.7 kWh/m3
Recovery factor ≈ 40% Recovery factor ≈ 40–60%
High capital costs Low capital costs
High operating costs Low operating costs
Desalted water cost ≈ (0.90–1.40) $/m3
(MSF) – 0.7–1.0 (MED, TVC)
Desalted water cost≈ (0.50-0.70) $/m3 (in the
most part of SWRO plants) and 0.36 $/m3 (from
brackish water sources)
Table 1: Compares the reverse osmosis process to the most common thermal processes.
(Macedonio, et al., 2012)
d) Reverse Osmosis:
The most common form of membrane desalination is reverse osmosis (RO). About 60%
of all desalination plants run on reverse osmosis technology. Figure 1 demonstrates the need for
membrane technologies to be improved to produce water with salt concentrations as low as MSF.
It is the better process when it comes to electricity consumption per liter of water produced. The
water starts off by being treated to remove any suspended, colloidal matter that could clog up the
membranes (Sadhwani, et al., 2005). Some common chemicals used in this process are ferric
(III) chloride and polyacrylamide [3]. After pre-treatment the water is pressurized to create a
gradient between the two sides of the membrane it will pass through. It requires energy to
pressurize the water and to have it flow through at a determined rate. Throughout the RO
process, the water goes through a series of membranes, each of which is optimal for filtering out
a certain size range of particles.

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The Reverse Osmosis Process
Figure 2: Notice how the concentrated seawater disposal is left out in the open. In other
words, it gets directly released back into the ocean. (Ali, 2010)
The main drawbacks with RO are due to the chemicals that must be added to prevent the
membranes from getting damaged and the pressurized discharge water. When salty water passes
through the membranes, there is the tendency for compounds to form on the membrane and
prevent water from passing through. Membrane efficiency is determined by the material it is
made out of and the surface area. Engineers try to make membranes with as high of a surface
area as possible within a given area. This increases the permeability of the membrane and
decreases the amount of antiscalants necessary. The pressurized water is high in CO2, which
acidifies the ocean (Stanley, 2009). Coral reefs are already experiencing a decline in population
due ocean acidification. Calcite, the main component of a coral reef system, dissolves readily in
water below a pH of 8 (check for accuracy and exact pH). Multi-stage flash desalination does
not discharge water that is high in CO2 but it has other issues.
e) Multi-Stage Flash Desalination:
Thermal desalination, the most popular of which is Multi-Stage-Flash desalination (MSF),
uses thermal energy to evaporate freshwater from the saltwater. Since it requires a large amount
of energy to operate at 110-120 degrees Celsius (Latteman, Hopner, 2008), MSF has higher

8. 8
energy costs than the membrane processes. MSF is the process used in approximately 20% of all
plants worldwide. Figure 1 shows how the seawater flows through pipes to the heating steam
and then through three different pressure stages.
The Multi-Stage Flash Desalination Process.
Figure 3: Displays the MSF process. The seawater is fed through the heating steam, which
brings the temperature to around 112 degrees Celsius. After the seawater is heated up it goes
through stages that apply decreasing grades of pressure. Once the freshwater evaporates in each
stage it is captured by a bath located at the top of each pressure stage. (Jayachandran, 2011)
The three stages, depicted by the blue shaded L-shaped regions, are held at different
pressures. The first stage is held at the highest pressure (Macedonio, et al., 2012). The water is
then passed through stages of decreasing pressures because decreasing the pressure of the
atmosphere within each stage lowers the boiling point of the water (Macedonio, et al., 2012). As
freshwater evaporates out of the saltwater, it rises to the top of the current stage where it is
captured in a bath. Once captured, the freshwater is fed to a pipe and then is transported for
storage. Of all of the thermal processes, MSF requires the least amount of anti-scalants because
of the way it uses steam to heat up the saltwater instead of directly applied metal (Macedonio, et
al., 2012). Anti-scalants are used to prevent the build-up of undesired compounds on the
equipment. This is important when considering the chemical makeup of the brine waste.

9. 9
A drawback of MSF, like all other thermal processes, is that it requires the addition of
biocides to prevent the build-up of bacteria that would thrive in its high temperature, high
moisture environment (Sadhwani, et al., 2005). Another drawback is that MSF requires at least
four times as much energy as RO (Macedonio, et al., 2012). In the Arabian Gulf, where fossil
fuels are cheap, this isn’t as much of a controlling factor, which explains why MSF is so popular
in this area. Also, the brine reject stream from an MSF plant is 5-15 degrees Celsius warmer
than average ocean temperatures (Latteman and Hopner, 2008). Surface ocean temperature plays
a key role in atmospheric temperature, wind patterns, and ocean circulation (Stanley, 2009).
The change in ocean circulation patterns would alter the nutrient distribution in the discharge
area. Populations of many organisms are only temporarily resistant to these types of changes.
f) The Brine Waste
An engineering difficulty characteristic of them both is the brine waste. After looking
closely at Figure 2 and figure 3, both diagrams contain brine discharge pipes that are suddenly
cut in the picture. This demonstrates the lack of pre-treatment and the lack of attention that the
brine discharge gets in the design of a plant. Table 2 displays the concentrations of key elements
contained in both the brine waste and average seawater.
Elemental Concentrations of the Brine Waste
Element Seawater
g/Liter
Brine Reject
g/Liter
Calcium .450 .814
Magnesium 1.520 2.751
Sodium 11.415 20.657
Potassium .450 .814
Bicarbonate .250 .452
Chloride 20.8 37.639
Sulphate 3.110 5.628
Silicon .005 .009
Total Dissolved
Solids
38 68.764
Table 2: Shows the amount of grams per liter of the intake
water (seawater) and the brine reject stream. The reject stream
is approximately 1.81 times as concentrated as the seawater.
This data is taken from an RO plant. (Sadhwani, et al., 2005)
The brine waste is 1.4 to 3.3 times as concentrated as ocean water and commonly
contains over 68 grams per liter of dissolved ions (Sadhwani, Veza, Santana, 2005). According
to Sadhwani, Veza, and Santana there are 37.639 grams of chlorine in each liter of brine waste,

10. 10
meaning over 913 billion kilograms of chlorine are contained in the brine waste globally every
year (Appendix I). The brine is highly corrosive as it flows through the metal piping, corroding
off trace amounts of heavy metals and releasing them into the ocean as well. Iron, nickel, and
chromium are such examples (Lattemann and Hopner, 2008). Iron, chromium, and nickel are
created from the corrosion of steel discharge pipes and if the heat exchangers in the MSF process
contain nickel-iron exchangers (Lattemann and Hopner, 2008).
4) Environmental Impacts
When a desalination plant is up for proposal, the site choice for its brine discharge pipes
is important. Plants try to discharge their reject streams in an active tidal area that has a steep
continental slope (Purnala, 2003). Bays are an example of an area that would be prone to a
discharge pipe because of the slow moving, shallow water that doesn’t get as much of an
opportunity to mix with the remaining ocean. Good site choice is either not being practiced, or is
not enough to prevent the impact of the brine waste because chlorine has been found above toxic
levels in discharge sites (Latteman, Hopner, 2008). The potential impacts cannot be ignored.
a) Alteration of marine ecosystems:
Chlorine is added in both the RO and MSF processes to prevent biofouling. Organisms
get caught in the membranes of reverse osmosis plants and bacteria thrive in the high moisture,
high temperature environment that an MSF plant provides. Biocides and chlorine will kill
important microorganisms such as plankton and algae. Sadhwani, Veza, and Santana reported
declining populations of three species of algae off the Mediterranean coast of Spain. Not only do
larger organisms, such as whales and fish, rely on them for food, they also rely on them for
environmental composition.
Plankton soak up sunlight, impacting surface temperature and the maximum depth in the
water column that light can reach. Autotrophic plankton use CO2 to undergo photosynthesis and
increase ocean pH in the process (Stanley, 2009). The concentrate is already slightly acidic due
to pretreatment chemicals like hydrochloric acid and the carbonation of the salty water during the
process (Lattemann and Hopner, 2008). If it also kills the organisms who buffer the pH, it
creates a positive feedback loop for more acidic seas. Biological organisms are not only
responsible for buffering ocean pH, but also aid in sediment stability.
b) Elevated rates of coastal erosion:
The sediment stability suffers due to the regression of algal populations that hold the
sediments together (Sadhwani et al. 2005). These populations have fallen in waste sites due to
elevated levels of chlorine and chlorine containing compounds, such as hypochlorite (Lattemann
and Hopner, 2008). Since reject water from RO plants is more dense than the water in the ocean,

11. 11
it will sink to the benthic zone. As benthic organisms, which reside in the sediments of the ocean
floor and help to hold them together, are constantly exposed to changes in salinity and chlorine
containing compounds, they will experience population decreases. As the benthic organisms
population decreases, the near shore sediments weaken and their ability to handle stress from the
shoreline will decrease, causing increased erosion rates. This is combined with the fact that
growing urban centers built on the coast will be applying increasingly heavy loads to the
sediments in the future. In fact, two thirds of the world’s population lives within 400 km of the
ocean (Hinrichsen, 2007).
c) Intrusion of inland groundwater tables:
As the near shore environment becomes more saline, the salt gradient between it and the
continental ground water table becomes sharper. The coastal saline water then balances out this
gradient by intruding into the continental groundwater tables, which contain freshwater. Fresh
groundwater is already being pumped at a rate that is higher than it is being replenished, which is
done naturally by rain, snow melts, and glacial melting. The National Oceanic and Atmospheric
Administration, which is a part of the U.S. Department of Commerce, reports that salinated
groundwater occurs randomly in nature, but increasing the salinity of coastal waters will only
increase its likelihood.
Salty groundwater changes the soil composition and requires the groundwater to be
desalinated before it is desirable. The soil composition has an impact on agriculture in the area.
High levels of sodium cause soil to have concrete type properties, making it difficult for plants to
acquire water and nutrients (Pearson, et al., 2003). The roots of the plant also have difficulty
spreading through soil under this condition (Pearson, et al., 2003). It is also proven that plants
spend a lot more energy trying to absorb water from a brackish source. Therefore, if the salt
content of the groundwater increases, the plants’ ability to absorb water from the ground will
decrease. Growing crops requires more water under increasingly saline soil conditions.

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A Look at a Grounwater Aquifer
Figure 4: This figure shows how saltwater intrudes into a freshwater aquifer. Water
from an RO plant sinks due to its high density and will push existing saltwater further up
into the aquifer. (Barlow, 2003)
The potential environmental impacts of desalination are elevated rates of coastal erosion,
alteration of marine ecosystems, and the salination of inland water wells. The alteration of
marine ecosystems has to do with toxic levels of chlorine, elevated salinity levels, and elevated
temperature levels. Some of these changes are due to the influx of brine waste into the local
environment. The brine waste must be treated in some way before it is dumped back into the
natural environment. Some potential solutions involve precipitation reactions and electrolysis
reactions.
5) Possible Solutions
a) Precipitation of silver chloride:
Silver chloride, which has the chemical symbol AgCl, precipitates easily in solution. It
has a solubility product constant equal to 1.77x10^-10 (Chang, 1986), meaning that if 143.34
grams of AgCl are added to one liter of water, only 0.002 grams of AgCl will dissolve at 25
degrees Celsius, which is 77 degrees Farenheit. This makes it an easy target compound when

13. 13
trying to investigate ways of precipitating out chlorine at high levels. Silver chloride is used in
spectroscopy to make mini cells (Cystran, 2012) and has several antibacterial applications as
well. When cement and glass are manufactured with silver chloride, the AgCl prevents bacteria
and other micro-organisms from growing on the concrete or glass (saltlatemetals.com).
Saltlakemetals.com sells one kilogram of silver chloride for $2,150.00, meaning that the
production of silver chloride is very lucrative. A silver nitrate solution could be purchased in 55
gallon drums and added to the brine reject stream in the presence of a salt screen. The salt screen
would be there to capture the silver chloride precipitate. However, the nitrate would be left over
in large amounts. It would be best if a pure silver solution could be added but that would be
difficult to find. It is usually present with an anion such as nitrate or chloride. Chlorine attacks
membranes so eliminating the chlorine will reduce the damage done to the membranes and
increase their effectiveness (Macedonio, et al., 2012).
b) Electrolysis of aqueous sodium chloride:
An electrolysis reaction involving aqueous sodium chloride would produce hydrogen gas
and chlorine gas as well as sodium hydroxide. The reaction could produce enough gas to
generate daily revenues of $2,197,050/day at an electricity cost of about $49,572/day at a
standard desalination plant (Appendix II). It is important to note that hydrogen gas is produced
from natural gas at a cheaper cost than from the electrolysis of aqueous sodium chloride, but
electrolysis also creates chlorine gas. These numbers are under the assumption that all of the
hydrogen and chlorine gas is sold. They are also under the assumption that the electrolysis
reaction has a 100% success rate, but it would be much lower in reality.
electrolysis
2 NaCl(aq) + 2 H2O(l) 2 Na+(aq) + 2 OH-(aq) + H2(g) + Cl2(g)
Figure 5: The chemical equation for the electrolysis of aqueous sodium chloride. It
requires an applied voltage of 1.36 volts. (Bodner Research Group)
The daily cost also does not include the costs of the plant property and equipment that
goes into the electrolysis reaction. Prices of the equipment are only available to companies who
are willing to purchase, but a $2,147,478 daily cost cushion is worth looking into considering the
long term nature of the operation. Some of the initial costs would be towards electrolysis
equipment that would last for multiple years. Any profits from the electrolysis operation could
go towards research and development into desalination technology that runs on hydrogen as fuel.
Once research points to hydrogen powered plants being feasible, the hydrogen gas could start
being stored for future use. This would reduce one of the main drawbacks of desalination, the
energy cost.

14. 14
The aqueous sodium hydroxide is another major factor. Stratification could be used to
extract the sodium hydroxide, but given how many different ions are contained in the brine waste
it is unclear how well it would stratify. It is important to note that CO2 and aqueous sodium
hydroxide create baking soda as a precipitate. Water in reverse osmosis plants is slightly
carbonated due to the pressure and may be slightly acidic due to the addition of hydrochloric acid
during pretreatment (Sadhwani, et al., 2005). Aqueous sodium hydroxide creates a basic
solution but if it could be counteracted to produce baking soda when exposed to the CO2 in the
water or neutralized by the HCl, it wouldn’t be a problem.
6) Recommendation:
The final recommendation is to test the electrolysis of the aqueous sodium chloride. This
will create hydrogen gas, chlorine gas, and aqueous sodium hydroxide as by-products. The
hydrogen gas and chlorine gas could be sold for the profit and the proceeds could go towards
research. The research would be to develop desalination equipment that can run on hydrogen.
Hydrogen burns more efficiently than natural gas and has no by-products. This would decrease
the amount of fossil fuels consumed throughout the process, thus driving down the annual cost of
energy and cutting fossil fuel emissions. Such benefits may draw federal subsidies.
The main caveat of the electrolysis reaction is the aqueous sodium hydroxide that is left
over. This could either be partially neutralized by HCl that is already added in the process, or, in
the case of a reverse osmosis plant, it would react with CO2 in the water to produce baking soda.
Another caveat is how the reaction would occur in the midst of the other ions in the brine waste.
Reactions conducted in lab often contain pure solutions, rather than a mix of several ions (Table
2). An economic study determined that this reaction is well worth researching on a small scale.
7) Conclusion:
Desalination is going to be a big part of our lives going forward as the world enters a
global water crisis. Experts are even predicting world wars fought over water in the coming
centuries. Desalination is the only option today to capitalize on the large saltwater reservoir,
which is about 97% of Earth’s water. The high fossil fuel consumption is easy to target as a
weakness but the brine waste is also devastating. It can alter ecosystems, increase coastal
erosion, and cause the intrusion of groundwater tables. If the desalination industry ignores the
impacts of its brine waste, these environmental impacts will start occurring and escalating. An
electrolysis reaction targeting the aqueous sodium chloride would aim to reduce not only the
energy costs, but more importantly the brine waste. It could be used in conjunction with other
chemical reactions that may target different elements.

15. 15
8) References:
Alameddine, I., & El-Fadel, M. (2007). Brine discharge from desalination plants: A modeling
approach to an optimized outfall design. Desalination, 214(1–3), 241-260.
Ali, “How do you like your brine?,” wordpress.com, Septe.ner 2010. [Online] Available:
http://walkerrant.wordpress.com/2010/09/02/how-do-you-like-your-brine/. [Accessed Apr.
14, 2012].
Barlow, Paul M. 2003. Ground Water in Freshwater-Saltwater Environments of the Atlantic
Coast. Circular 1262. U.S. Geological Survey.
Bodner Research Group. “Electrolytic Cells”. Bodner Research Web, Purdue University.
[Online]. Retrieved from http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch20/faraday.php#aq.
Chang, J. C. (1986). "Solubility Product Constants." Handbook of Chemistry and Physics. Weast,
Robert C., ed. 67th ed. Boca Raton, FL: CRC Press, Inc., p.B208.
Environmental Protection Agency. (2012). “National Primary Drinking Water Regulations”
[Online]. Retrieved from http://water.epa.gov/drink/contaminants/index.cfm.
Cystran Ltd. (2012). “Silver Chloride (AgCl)” [Online]. Available:
http://www.crystran.co.uk/silver-chloride-agcl.htm. [Accessed April 14, 2012].
Ganesh, R., Leong, L., Schroeter, J. H., & Tikkanen, M. W. (2001). Guidance manual for the
disposal of chlorinated water (Manual). Renton, Washington: The Vita-D-Chlor Company.
Hawthorne, J. (2009). “The Current State of Desalination” [Online]. The International
Desalination Agency, 2009 report. Available from
http://www.idadesal.org/PDF/the%20current%20state%20of%20desalination%20remarks%20no
v%2009%20by%20lisa%20henthorne.pdf.
Henthorne, L.W. (2011). “The State of Desalination 2011”, [Online] Retrieved from
http://desalination.edu.au/wp-content/uploads/2011/09/IDA-State-of-Desalination-2011.pdf.
Hinrichsen, D. (2007). “Ocean Planet in Decline” [Online]. Peopleandplanet.net. Available
from http://www.peopleandplanet.net/?lid=26188&topic=44&section=35. Accessed:
November 7, 2007.
Jayachandran, “Sea water desalination” September, 2011. Tecneem.co.in. URL:
http://www.techneem.co.in/2011/09/sea-water-desalination.html
Lattemann, S., & Höpner, T. (2008). Environmental impact and impact assessment of seawater
desalination. Desalination, 220(1–3), 1-15.

16. 16
Macedonio, F., Drioli, E., Gusev, A. A., Bardow, A., Semiat, R., & Kurihara, M. (2012).
Efficient technologies for worldwide clean water supply. Chemical Engineering and
Processing: Process Intensification, 51(0), 2-17.
Pearson, K. E., Warrence, N. J., Bauder, J. W. (2003). “The basics of salinity and sodicity effects
on soil physical properties” [Online]. Retrieved from
http://waterquality.montana.edu/docs/methane/basics_highlight.shtml
Purnalna, A., Al-Barwani, H. H., & Al-Lawatia, M. (2003). Modeling dispersion of brine waste
discharges from a coastal desalination plant. Desalination, 155(1), 41-47.
Sadhwani, J. J., Veza, J. M., & Santana, C. (2005). Case studies on environmental impact of
seawater desalination. Desalination, 185(1–3), 1-8.
Stanley, S. M. (Ed.). (2009). Earth system history (Third ed.). W.H. Freeman and Company:
Clancy Marshall.
United States Geological Survey. (2012) “Water Resources” [Online]. United States’ Department
of the Interior. Retrieved from http://www.usgs.gov/water/
National Academy of Engineering. (2008) “Introduction to the grand challenges for engineering”
[Online]. Retrieved from http://engineeringchallenges.org/cms/8996/9221.aspx.
9) Appendix:
I) (37.639 grams Cl- / Liter)*(66,480,000 cubic meters / day)*(1,000 Liters / cubic
meter)*(365 days / year)*(1 Kg / 1,000 grams)=913,317,862,800 Kg Chlorine
II) a. For one liter: (0.27 amps)*(3600 seconds / hour)*(24 hours / day)*(1 coulomb / 1
amp)=23,328 Coloumbs / day
b. (23,328 Coulombs / day)*(1 mol e- / 96,485 coulombs)=0.242 mols e-
c. (0.242 mols e-)*(1 mol e- / 1 mol Cl2 or H2)=.242 mols H2 or Cl2
d. (0.242 mols e-)*(70.91 grams Cl2 / 1 mol Cl2)=17.16 grams of Cl2 per liter
(0.242 mols e-)*(2.016 grams H2 / 1 mol H2)=0.488 grams of H2 per liter
e. For standard plant of 25,000 cubic meter per day capacity: (17.16 grams Cl2 and
0.488 grams H2 / 1 Liter)*(25,000,000 Liters / day)=440,250 kg Cl2 per day and
12,200 kg H2 per day
f. Revenues: (440,250 kg Cl2)*($1 / kg)=$440,250
(12,200 kg H2)*($144 / kg)=$1,756,800
Total Revenues: $2,197,050 per day
Expenses: (1.5 volts)*(0.27 amps)*(24 hours)*(25,000,000 liters)*(1 kW / 1,000
Watts)*($0.204 / kWh)=$49,572 per day
http://www.chemicool.com/elements/hydrogen.html