Ms. Nikki A Mehalic
12
Development of a Solar-Powered Water-Purification Device for Developing Countries
Environmental Technology
Commercialization Plan
Billions of people currently face water scarcity, and typical purification systems are energy intensive, struggle to get
funding, and are extremely complex. This system employs simple principles of solar distillation to purify water for
those in need in developing countries. Its simplistic design is made up of inexpensive, easily accessible, and
adaptable materials that will boost local economies while saving billions from dehydration and other water scarcity
concerns.
Executive Summary
The purpose of this project was to develop a small, cost-effective, and efficient solar distillation prototype
to provide pure water to individuals and families in the developing world. Many of the commonly used water
purification devices implemented in these countries are expensive, complex, and energy intensive. Modifying
currently available systems, this project was designed to be environmentally-friendly and accessible to those in need.
The project consisted of three main phases: building the prototype, testing its efficiency, and testing its
purification ability. Solar distillation principles, which imitate the natural water cycle, were used in the design
development. The system consists of a skillet and a lid that houses the water as it evaporates. As it recondenses,
PVC piping transports the water to a receptacle at the bottom of the structure. Efficiency was investigated by
measuring the system’s output of water over time, both outside using only the sun and inside using heat lamps. To
test the prototype’s purification ability, total dissolved solids [TDS] and pH levels were measured for a variety of
samples and for all water outputs by the system.
The market for this product is large because over two billion people currently face water scarcity problems.
The system would be intended for small-scale use in developing countries and would be marketed directly to
individuals and families, as well as to non-profit organizations. The cost-effectiveness, simplistic design, adaptable
materials, and low environmental impact of this system give it a competitive edge that makes it a desirable water
purification solution.
Problem Statement and Proposed Solution
The World Economic Forum’s January 2015 Edition announced that the water crisis is the number one
global risk of devastation to society (“Water Facts,” n.d.). While billions of people, especially those in developing
countries, are currently facing water scarcity issues, the typical water purification solutions employed are entirely
unsatisfactory. Most systems employ very energy intensive tactics to purify water, in turn causing environmental
damage. Because these systems are often very large and expensive, they struggle to receive funding, and are
generally too complex to manufacture and repair without outside help. In an attempt to find a solution to this
problem, a small-scale solar distillation prototype will be made to act as a source of water purification for those in
need. This system will be extremely environmentally friendly as it requires no energy generation nor harmful
chemicals, will be inexpensive for families, and will be very simplistic to use and maintain.
Summary of STEM Concepts and Principles
This device follows the principles of a traditional solar still, in which sunlight alone is utilized to mimic the
Earth’s natural water cycle and purify contaminated water. The evaporation and condensation of water, along with
basic properties of gravity, are essential to the collection of purified water. When contaminated water is placed in
the upper basin of the prototype, it is gradually heated by the sun, and will begin to slowly steam and evaporate
upward to the underside of the plastic wrap covering of the upper basin. Upon reaching the plastic wrap, the water
vapor will condense into water droplets. The prototype is built with the plastic wrap weighted in the center to create
a constant downward slope. Because of this design, gravity slowly attracts these droplets down the slope of the
plastic wrap until they reach its lowest point in its center. Here, their momentum causes them to drop off of the
plastic wrap and fall into a pipe that is fixed through the upper basin and rests right below the lowest point of the
plastic. The driving idea behind the effectiveness of solar stills is the principle that when water is heated and
evaporates, only the pure H2O evaporates and all contaminants are left behind. This important underlying concept
makes solar distillation a valuable alternative to typical, energy-intensive methods of purification and desalination.
The purity of water is determined by a multitude of different factors, but this project’s experimentation focused on
total dissolved solids [TDS] and pH level. High TDS levels in water can be harmful for consumption, and extreme
pH values also threaten safety. Though the testing of this system provided promising purification results, additional
scientific testing must be completed to confirm the results and test other measures of purification, including the
removal of bacteria and parasites. Along with that, in order to improve the efficiency of the system, more testing
needs to be conducted in a variety of climates. With this additional information design improvements and
modifications can be made.
Commercial feasibility
Problem:
Billions of people currently face water scarcity issues while many of these people have easy access to
various sources of contaminated water, like oceans and lakes. The major problem these individuals face is finding
means of purification, and most water purification systems are extremely energy intensive, struggle to receive
funding, and are too complex for untrained individuals to manufacture or run.
Proposed solution:
A small-scale solar distillation prototype will be made to act as a source of water purification for those in
need. This system is extremely environmentally friendly as it requires neither energy generation nor harmful
chemicals, is inexpensive for families, and is very simplistic to use and maintain [Figure 1].
Target customers/intended users:
The target customers and intended users for this system would be individuals and families in developing
countries, especially those struggling with finding reliable means of water purification. This system was designed to
be used on a small-scale, so individuals and small families would be the intended users. Besides these families,
targeted customers could include non-profit organizations or large groups and communities that work to provide
help to those in need. Because billions of people currently face water scarcity issues, the potential market for this
system is very large.
Competitors:
This system’s competitors would be any company that sells water purification devices. Companies
providing large desalination plants to communities and large cities are one group of competitors. These companies
include IDE Technologies and Veolia, and their systems can cost up to 100 million dollars annually. Another group
of competitors would include those selling more similar, smaller-scale solar distillation systems, including H2O
Labs, whose products range in price from $1,500 to $3,100, and Aquamate, whose solar still kit is priced at $238.
Because charitable organizations only have the ability to support some companies, this system would also compete
with other companies that sell products to non-profit organizations.
Customer value proposition & competitive advantage:
Value of this device is shown in a variety of areas. The main concern of customers is having a reliable way
to purify water, which this device satisfies. Additionally, this device is extremely simple for customers to use and
maintain. Many other aspects of this system give it a competitive edge. For instance, this device requires no
generation of energy, so it has a very low impact on the environment. Because it is built small-scale, this device is
portable and only requires a small amount of space to be used. Also, it is very inexpensive compared to its
competitors, and while being inexpensive, it has the ability to promote local economies by encouraging the use of
local materials for its build.
Principal revenue streams:
This product would be marketed as two different packages. Both packages would include a detailed
instruction booklet with descriptions about how the system works and is built. This booklet would further detail
different options for materials. Along with this booklet, the first package would include the entire system assembled
[Figure 1]. The material cost for the full system is detailed in Table 1, and the cost comes out to be just below $50.
The total cost to produce the system is estimated to be around $80 when factoring in additional costs, like labor and
shipping. Package number one would be priced at $100, and a $20 profit would be expected. The second package
would include the instruction booklet and just the necessary, specialty materials needed for construction, like the
skillet, lid, PVC pipe, plastic wrap, tape, and the rubber pads. By allowing customers to use inexpensive, local
materials to build the main components of the system, they have the opportunity to cut costs and promote their local
economy. This package would be priced at $60 as the material cost is about $30. This package would impose
smaller additional costs since labor for assembly would be unnecessary; with $45 of total costs, a $15 profit could be
expected. Further into the future, additional packages may be offered that differ in basin size so the amount of water
produced can be tailored specifically to the needs of the customer.
Startup and operating costs:
The first startup cost necessary would be that to improve construction of the prototype and complete further
testing on samples of water with various types of contamination. Creating the packages to be sold to customers
would incur startup and operating costs. First, a book would be developed detailing specifics of solar still operation
and capabilities, as well as different design options and detailed descriptions of the building process. Variable
operating costs would include the reproduction of booklets and packages, as well as shipping costs. Fixed operating
costs would include factory real-estate. Labor costs could be considered both a fixed and variable operating cost.
Science and Technology Proof of Concept
Review of Literature:
Water Crisis
The World Economic Forum’s January 2015 Edition announced that the water crisis is the number one
global risk of devastation to society (“Water Facts,” n.d.). Over one billion people around the world do not have
access to water, while a total of 2.7 billion people face water scarcity problems during at least one month of each
year (“Water Scarcity,” n.d.). It is projected that by 2030, almost half of the world will live under high-water stress
(Powers, n.d.).
Water Purification
The purification, or distillation, of water is the transformation of contaminated water into safe, drinkable
water. According to McCracken and Gordes, “ninety-seven percent of the earth’s water mass lies in its oceans. Of
the remaining three percent, ⅚ is brackish, leaving a mere .5 percent as fresh water,” so water purification methods
are entirely necessary (McCracken & Gordes, n.d.).
Many factors impact the purity of water. First, total dissolved solids [TDS] are any minerals, salts, metals,
or other charged ions that are dissolved in water. TDS is measured by mg per unit volume of water or “parts per
million” [ppm]. Monitoring the TDS of water is important because high levels of TDS can be harmful to consume
and different levels of TDS exist in various water sources. For example, the Environmental Protection Agency
advises a maximum consumption level of 500 ppm (“What is TDS,” n.d.). Another factor, the “power of hydrogen”
[pH], is also important to consider when checking for water purity. The pH value is determined on a scale, from
zero to fourteen, where one side is acidic [zero] and the other side is basic [fourteen]. Water must be neutral, inbetween acid and basic on the pH scale, to be safe for consumption (Kemker, 2014).
Solar Distillation
All of the freshwater on Earth has been “solar distilled,” or purified by sunlight, through the water cycle.
Imitating the water cycle, solar distillation uses solar energy to evaporate and condense water in a closed system
(“Solar Distillation,” n.d.). There are many benefits of solar distillation. First of all, this method uses much less
energy to purify water than the alternatives, making solar stills environmentally-friendly. Freshwater and saltwater
sources can both be made safe for drinking with a solar still because when water evaporates, salt and other impure
substances are left behind. Therefore, solar distillation, especially in areas already near a large source of water, can
reduce a country's dependence on rainwater and ensure supply of water during times of drought. Other benefits of
this technique, as highlighted by McCracken and Gordes, include, fostering “cottage industries, animal husbandry,
and hydroponics for food production in areas where such activities are limited by inadequate supplies of pure
water,” and permitting “settlement in sparsely-populated locations” (McCracken & Gordes, n.d.).
Solar Still Designs
Solar stills are devices that distill water by trapping the heat from the sun to evaporate and condense
purified water (“Water: Purification Methods,” 2012). McCracken and Gordes state the premise behind solar
distillation with, “moisture rises, condenses on the cover and runs down into the collection trough, leaving behind
the salts, minerals, and most other impurities, including germs” (McCracken & Gordes, n.d.). To initiate this
process, most stills are made up of a dark, shallow basin with a glass cover. The dark surface better absorbs heat
and the shallowness of the basin allows the water to be heated much more quickly than if it were a deep tank. Also,
a downward sloping glass cover allows condensed water droplets to roll down and fall into a collection area
(McCracken & Gordes, n.d.).
Materials for solar stills need to be chosen carefully with consideration toward safety, longevity, cost, and
effectiveness. The basin that holds the water needs to be waterproof and a dark color for maximum sunlight
absorption (McCracken & Gordes, n.d.). The material used to cover the still is the next most important part of
construction because it must transmit as much light as possible into the still and then keep it from escaping. A glass
or a plastic is most frequently used for this cover (McCracken & Gordes, n.d.). The distillate trough is the area
where the purified water is collected, and is commonly made out of metal. It is also important to have an effective
sealant for making the structure airtight. The sealant should withstand heat, sunlight, and other weather conditions
and be compatible with the other building materials (Arunkumar et al., 2012; McCracken & Gordes, n.d.).
Marketed Products
Gabrielle Diamanti has developed a unique open-source solar still design called the Eliodomestico
(Diamanti, n.d.). This product is made up of three main components, a black boiler to hold the contaminated water,
a collection basin, and a pipe to connect the two. When water in the top boiler begins to vaporize, the building
pressure pushes the steam to escape the boiler by moving down through the middle pipe (Treacy, 2012). After the
vapor travels down the middle pipe, it condenses on the sloping top of the collection basin and then runs down into
the basin. Diamanti’s system costs $50 to build, but is not yet on the market (Treacy, 2012).
Scientists at Purdue University have developed a prototype solar still in a tubular design. Their still consists of a
large parabolic reflector on which sits a transparent pipe (Badore, 2013). The large size of the parabolic reflector is
unique compared to most solar still designs but offers strong amplification of the sun’s rays for heating the water
inside the tube (Badore, 2013).
One company, Suns River, has created a solar still that can feed directly from streams, saline wells, wastewater sources, rivers, and oceans (Markham, 2012). Their product’s design looks similar to a traditional singlebasin still with a sloping cover, but Suns River claims it can increase standard still productivity by a factor of five
while also cutting production and maintenance costs (Markham, 2012).
Testable Hypothesis:
A small-scale solar distillation system can be made that purifies water, has low environmental impact, and
is inexpensive and accessible to those in need in developing countries.
Methods:
Design
This prototype’s design was inspired by Gabrielle Diamanti’s Eliodomestico but included modifications.
Materials mainly consisted of household items that could easily be substituted to promote accessibility. The design
of the prototype consisted of four main components. A skillet was used on top that holds the contaminated water
and allows it to evaporate and condense on a lid. Supporting this basin, acting as a table, is a wooden box that
houses another basin and a PVC pipe which connects the two [Figure 1].
Build
The largest component of the prototype was a box-like structure constructed from three 16 in.x 16 in.
boards and one 16 in.x 16 in. board of lauan. The 16 in.x 8 in. board was originally a square like the others, but it
had to be cut to a smaller size so that the inside water-collection basin could be easily detached and pulled out from
the system. Each board was cut with an electric circular saw, and then four pieces of pine wood that were 1.5 x 0.75
x 16 in. were cut to support the edges of the box. This pine was screwed to the lauan with an electric drill and 0.25
in. screws into the shape of a box. Then, two pieces of melamine shelving, to be used for the top of the box, were
cut into 8 in.x 16 in. rectangles which would be screwed together with a mending plate because a 16 in.x 16 in. piece
was not available. Because the melamine was white, this square was painted with Rust-oleum Flat Protective
Enamel in black paint in order to help attract more sunlight to the prototype.
Another important component of the prototype was the PVC pipe that runs from the inside of the skillet
down to the bottom basin for the purified water. In order for the PVC to collect the evaporated and condensing
water in the skillet and then bring this water to the other basin, the PVC needed to go up through the wooden top of
the box and the skillet. A 1.25 in. paddle bit on a hand drill was used to cut a circular hole in the center of the
particle board piece. Because the PVC pipe had a diameter of 1.25 in., the hole made by the paddle bit was too
small for the PVC pipe and had to be shaved to a larger size with another drill-bit. Then, a hole had to be cut in the
skillet to also allow the PVC to move up through it. A hole saw was used to cut a hole in the skillet of a diameter of
1 in. This hole was then shaved down with a Dremel until the PVC fit snugly. Finally, after the PVC pipe could fit
up through the wooden piece and the skillet with a snug fit, the PVC was cut to a length of 14 in. so it would be the
correct length for the size of the device.
The top component was then completed by covering the skillet with a piece of Giant Eagle Plastic Wrap
and taping it down around the edges so it could be removed with ease. The actual glass lid to the skillet was added
on top of the plastic wrap to preserve the wrap and better contain heat inside.
A small plastic bowl was used for the bottom water-collection basin. The lid provided with the plastic
bowl was used to create a good seal around the container so any water vapor that was forced down the PVC to this
container would be unable to escape. A 1 in. paddle bit was used to cut a hole in this lid for the PVC to fit through.
Because this lid was plastic and bendable, the 1 in. hole fit the PVC with no extra shaving.
The entire system was then put together by first setting the particle board on top of the box structure and
then placing the skillet on top of both of those. The bottom container was placed inside under the box, and the PVC
pipe was run through all of the components starting with the skillet and pushing down.
Experimentation
Efficiency Testing
Outdoor Testing
For the first testing of the entire system, instead of using a permanent sealant, the tiny gap around the hole,
and the PVC were sealed with a thick layer of petroleum jelly so the water that was placed inside could not escape.
An analog thermometer was then placed inside of the skillet, and 2 cups of room-temperature tap water were
slowly poured inside. Then, Giant Eagle brand plastic wrap was stretched across the top of the skillet and taped
along its sides. Uxcell cylinder adhesive rubber pads, which easily stuck together and could be stacked to any
height, were attached to the underside of the glass lid. These pads were added to push the center of the plastic wrap
down, over the opening of the PVC, to create a downward slope. The downward slope was important in leading
condensed water droplets on the plastic wrap toward the center into the PVC pipe. The first two tests were
conducted in this fashion. Because the petroleum jelly proved to be an unreliable sealant, J-B Weld “Steel
Reinforced Epoxy” was used to permanently seal the PVC to the skillet. This sealant mixture was applied around
the PVC and the skillet in a thick layer with the same small paintbrush. The skillet with the sealant was sat and left
untouched to dry for 35 hours, exceeding the sealant cure time of 15-24 hours. The third test was conducted after
the sealant had cured and the following two tests followed the same procedure as earlier. For the sixth and seventh
test, 1.5 cups of water were placed into the prototype instead of 2 cups. The 2 cup amount was altered with intent to
increase water output, but all other procedural stipulations remained constant.
Indoor Testing
Because this prototype is intended to be used in a very hot, sunny environment, changes had to be made to
better simulate these conditions since the temperatures in the outdoor testing environment were low. In the first test
with altered conditions, the prototype was placed inside, and a 125 watt heat lamp was positioned above it, two cups
of room-temperature tap water were placed in the prototype, and the plastic wrap was replaced. The second test
followed the same procedure. For the third indoor test, two heat lamps were used instead of just one, and they were
both directed toward the prototype. The rest of the procedure remained the same. For the fourth heat lamp test, 1.5
cups of water were used inside of the prototype instead of the 2 cups always used in the past. The same procedure
from earlier was repeated for the two following tests. Another testing modification was made for the seventh indoor
test to again attempt to increase water output. A Sylvania “Spot-Gro” 60 watt light bulb, which claims to imitate
sunlight, similar to a UV light, was purchased and put in a small desk lamp to also direct heat toward the system
during the heat lamp tests. The intention was that the Spot-Gro bulb, in combination with the heat lamps, would
increase water output by better mimicking sunlight.
Purification Testing
Food Coloring
The first test run for purification purposes was a simple visual test. An amount of 1.5 tsp. of Kroger brand
red food color was mixed and dissolved in a glass of 2 cups of room temperature tap water. The purpose of the food
coloring was to determine if the prototype would evaporate and collect only pure [clear] water. The earlier testing
procedure was followed. The first red food coloring test was repeated to verify the previous results with quantitative
data. A half cup sample from this colored water was taken and placed aside. After the test, the collected water was
measured and kept as a sample. This exact procedure was repeated for a total of ten tests.
The samples from all ten tests were then analyzed with a light meter to compare the light level [lux]
through the liquids. Because a clearer solution will have a higher light level, these values showed how the prototype
can alter the clarity of the water. The intention behind this phase of testing was to examine the prototype’s ability to
remove unwanted particulates from the input water. The experimentation set-up consisted of a ring stand with the
ring positioned 7.5 in. off the table with a Vernier Go! Link light sensor positioned directly underneath with its
sensor placed in the center of the ring. A clay triangle was centered on the ring. A compact fluorescent light bulb
was positioned directly above the ring stand at 31 in. off the table. Samples to be tested for light level were placed
in a small, clear, plastic container and sat on the clay triangle so that the sensor was centered .375 in. below the
container. In the first test, the light level of a 2 tsp. sample of distilled water was measured as a control to compare
against the other samples. After light level of this sample was recorded, it was removed from the triangle and placed
back on the triangle after 10 s. to record another two readings. Afterward, a 2 tsp. sample of the output water and a
2 tsp. sample of the original input water was measured in the same fashion.
Salt Water
Next, a saltwater mixture was made to test the desalination ability of the prototype. Research suggested
that mock-ocean water is made at 35 parts per thousand salt (“Simulated Seawater,” n.d.). This measurement means
that for every 1000 grams [g.] of seawater, 35 g. of it is made up of salt. In order to mix this ratio, 35 g. of salt were
used with 965 g. of water [965+35=1000]. This solution’s total dissolved solids [TDS] value, a measure of salinity,
was measured using an HM Digital “TDS Meter.” The meter uses sensors to measure the amount of TDS when
dipped into the water sample and can read the TDS value for solutions ranging from 0 to 9990 parts per million
[ppm.]. This first saltwater solution had too high of a salt concentration for the meter to read [>9990 ppm] and the
meter displayed “---”. Despite the absent reading on this test, 1.5 cups of the salt water sample were placed inside
the skillet and the plastic wrap was replaced. Two heat lamps were directed at the prototype and temperatures were
recorded. After seven hours, the prototype was checked and water had leaked from the skillet and all over the
collection container and the floor. A crack in the sealant was observed. A fresh mixture of the sealant was applied
around the PVC and the skillet in a very thick layer with the same small paintbrush as before. The sealant was left
inside and untouched to dry for over 72 hours, exceeding the cure time of 15-24 hours. After the 72 hours, a fresh
mix of the salt water solution was made by mixing only 1 tsp. of salt with 2 cups of water in order to get an accurate
reading on the TDS meter. The meter was then used to measure the amount of TDS, or in this case, salinity, in the
water. Starting with this test, HACH “Aquacheck” strips were also dipped into the water and used to measure pH
according to a color comparison scale on the bottle. The same earlier test procedure was followed and at the
conclusion of this test, the water in the collection basin was measured again for TDS and pH.
The following test’s saltwater solution was made with the original ocean-water ratio and TDS and pH were
measured. The same previous procedure was followed for this test and the following two. For the next ten tests,
saltwater solution was again made by mixing 1 tsp. of salt and 2 cups of water until fully dissolved, otherwise, the
same previous procedure was followed.
Pond Water
Water from ponds and creeks was collected and tested for the next stage of testing. Samples were taken
from the ponds between Misty Oak Pl. and Eastchester Dr. in Gahanna, Ohio. Clean and empty plastic water bottles
were directly immersed in the water source and held under until filled. For the nine pond water purification tests,
1.5 cups of this pond water were first measured for TDS and pH and then poured into the skillet. The same earlier
procedure was followed.
Discussion:
Cost Analysis
All of the materials used to build the prototype for this project were selected because they were already
available, but they can be easily adapted. The cost of materials is recorded in Table 1.
Testing Results
The outdoor tests of the prototype serve as the first set of efficiency testing results. The consistent output
of water provides valid proof of concept; the prototype worked as its design intended. No system leakages occurred,
excluding the 11/5/15 test, the components of the system were sealed, and water could only enter the collection
container by first evaporating, condensing, and dropping into the PVC. Outdoor efficiency results ranged from .75
tsp. to 2 tsp. over an average period of six hours. Therefore, during the outdoor water tests, the prototype
successfully output water using only solar energy, but with low levels of return.
The indoor heat lamp tests of the prototype serve as the second set of efficiency testing results. The heat
lamps better mimicked the weather that the prototype would be ideally be exposed to, and, in turn, the water inside
of the skillet reached much greater temperatures. The UV light and radiation from the sun could not be modeled by
the heat lamps, so this intended environmental aspect was absent. Indoor efficiency results ranged from .25 tsp. to
5.25 tsp over an average testing period of six hours. The consistent output of water again provides valid proof of
concept because no system leakages occurred, the components of the system were sealed, and water could only enter
the collection container by first evaporating, condensing, and dropping into the PVC.
After the prototype was tested for efficiency, it was tested for effectiveness at purifying water. The first
purity test involved mixing food coloring into the sample of testing water. Comparing the samples and a sample of
distilled water from the food coloring test with a light level sensor showed a drastic increase in light level between
the food coloring sample and the output sample in all tests [Graph 1]. These results suggest that after distillation by
the prototype, the clarity of the water improved significantly [Table 2].
Another group of purity tests measured the prototype’s desalination ability. Salinity of water was measured
using a TDS meter, and results show that the output water’s salinity was drastically lower than that of the input
water in each test [Graph 2]. The output water also contained less TDS than the tap water did before even making it
a salt solution. Analysis of the results shows that there was a statistically significant difference between the TDS in
the input water and the output water, as well as between the tap water and the output water [Table 3]. The pH of the
water remained constant at a neutral 6.8 for each measurement.
The last group of purification tests measured the prototype’s ability to purify pond water. As shown in
Graph 3 and Table 4, the output water had a more neutral pH than the beginning sample, and the number of TDS
significantly dropped in each test [Graph 4, Table 5]. Neutralizing the pH and decreasing the TDS in the water
improve its quality and make it safer for consumption. As a result, the prototype seems to also be successful at
purifying pond water.
Conclusion:
The purpose of this project was to design, build, and test a solar distillation device that is smaller, more
portable, efficient, and inexpensive than the systems currently available. While the prototype fell short regarding
efficiency, the design was relatively inexpensive and portable with promising purification results. The efficiency,
represented by water output over time, of this prototype was not satisfactory and cannot compare to other solar stills
and purification systems on the market. The target environmental conditions in which this system is intended for
use could not be fully simulated, so the true efficiency ability of this system remains unknown. A combination of
high heat and large amounts of sunlight would likely increase water output.
The design of the prototype, however, had some benefits because of its portability and simplicity. The
system is basically just a 16 in. x 16 in. box. The inner basin for water collection also easily detaches for quick
access to and transport of the purified water. The cost analysis presents the price of this system to be $49.85, which
is slightly below Gabrielle Diamanti’s Eliodomestico model. This cost is not too high, but ideally improvements
would be made to further decrease the cost. Because the entire system was made from common materials, it can be
easily adapted for availability. For instance, this prototype uses a skillet for the main basin, but a variety of sturdy
materials, like clay, could be substituted and work well. Therefore, local artisans could craft a similar design to this
prototype with their own inexpensive, available materials. Because the system only consists of a few vital
components, building it is simplistic. Compared to purification systems that run on complicated technology,
building and repairing this system is ideal for the common-person with no background knowledge or experience.
Additionally, this system is intended to be largely a one-time cost. In this specific design, however, plastic wrap
and tape were used and replaced with each test; these materials would incur a small variable cost with use. Because
the variable cost is low, this system, if efficiency was increased, would easily pay for itself.
This prototype’s purification component produced promising results. The heat lamp tests, which simulate
ideal environment temperature, created output water with less TDS and a more neutral pH each time. In the salt
water tests, the huge drop in TDS represents salt levels drastically decreasing. Therefore, this system seems to be
not only effective at purifying water, but also at desalinating it.
Recommendations
Many alterations to testing procedures and design are recommended in order to increase the efficiency and
results. First, this system should be tested in the summer when the weather is very hot and sunny. Ideally, testing
would take place in a climate near the equator, but summer testing would at least better mimic the hot and arid
conditions in the developing countries for which this prototype is intended. The design of the prototype should be
altered to promote ease and decrease cost. A more sturdy and enduring material should replace the plastic wrap
cover to the main basin. The plastic wrap was inconvenient because it had to be constantly replaced, so it became a
variable cost. Creating a sealable spout into the main basin would also make the entire system more airtight and
make it much easier to put new water into the system. Finally, extensive testing of purification should be
emphasized with focus on measuring a larger variety of factors that impact the purity and safety of water.
Acknowledgments
First, I owe many thanks to my instructor, Mr. Bruns, for answering every one of my excessive questions
about my project. I would also like to thank him for helping me through multiple construction challenges and for
providing me with many of the materials I used for testing. Without his answers, help, and contributions, my project
would have remained just an idea. I am very gracious for all of the assistance Mrs. Rice offered regarding the
formatting and writing of this paper. Jason Mehalic deserves special thanks for contributing countless ideas during
the design process, for being the driving force behind the construction of the prototype, and for his endless interest
and support. I am thankful for my parents’ allowing me to run long tests in inconvenient areas and for giving me
almost all of the materials I used throughout this process.
References
Arunkumar, T., Vinothkumar, K., Ahsan, A., Jayaprakash, R., & Kumar, S. (2012). Experimental study on various
solar still designs. Accessed 01 Nov 2015: http://www.hindawi.com/journals/isrn/2012/569381/#B2
Badore, M. (2013, October 28). Sun-powered water purification system created by Purdue scientists. Accessed 03
Nov 2015: http://www.treehugger.com/clean-water/sun-powered-water-purification-system-createdpurdue-scientists.html
Diamanti, G. (n.d.). Eliodomestico : Gabriele Diamanti. Accessed 01 Oct 2015:
http://www.gabrielediamanti.com/projects/eliodomestico/
Kemker, Christine. (2014, June 13). Turbidity, total suspended solids and water clarity. Accessed 15 Oct 2015:
http://www.fondriest.com/environmental-measurements/parameters/water-quality/turbidity-totalsuspended-solids-water-clarity/
Markham, D. (2012, May 11). Looking backward to move forward: Solar stills could be the low-cost leader in water
desalination. Accessed 02 Nov 2015: http://www.treehugger.com/solar-technology/looking-backwardmove-forward-solar-stills-could-be-low-cost-leader-water-desalination.html
McCraken, H., & Gordes, J. (n.d.). Original:Understanding solar stills. Accessed 01 Nov 2015:
http://www.appropedia.org/Understanding_Solar_Stills
Powers, M. (n.d.). Water Scarcity Issues: We're running out of water. Accessed 05 Nov 2015:
http://www.fewresources.org/water-scarcity-issues-were-running-out-of-water.html
Practices of science: Making simulated seawater. (n.d.). Accessed 03 Nov 2015:
https://manoa.hawaii.edu/exploringourfluidearth/physical/density-effects/density-temperature-andsalinity/practices-science-making-simulated-seawater
Solar distillation. (n.d.). Accessed 08 Oct 2015: http://www.appropedia.org/Solar_distillation
Treacy, M. (2012, September 11). Solar oven makes clean drinking water from salt water. Accessed 01 Nov 2015:
http://www.treehugger.com/clean-technology/solar-oven-makes-clean-drinking-water-salt-water.html
Water facts. (n.d.). Accessed 12 Nov 2015: http://water.org/water-crisis/water-facts/water/
Water: Purification methods. (2012, October 15). Accessed 20 Oct 2015:
http://channel.nationalgeographic.com/doomsday-preppers/articles/water-purification/
Water Scarcity. (n.d.). Accessed 05 Oct 2015: http://www.worldwildlife.org/threats/water-scarcity
What is TDS? (n.d.). Accessed 01 Nov 2015: http://www.tdsmeter.com/what-is
Appendix
Cost Analysis
Material
Brand
Skillet
eBay Food Network
$8.99
Glass lid
eBay Pampered Chef
$7.95
Lauan plywood
Lowe's
$14
Pine strips
Lowe's
$1.33
Screws
Amazon
$0.87
PVC
Home Depot Charlotte
$3.23
Container
Freund
$0.55
Paint
Rust-Oleum
$3.87
Sealant
J-B Weld
$3.23
Rubber pads
Adafruit
$2.85
Plastic wrap
Giant Eagle
$2.19
Tape
Scotch Magic Tape
$0.79
Total Cost
Table 1 Cost Analysis
Price
$49.85
Figure 1 Solar Still Prototype
Light Level Testing (Lux)
Overall Mean
Output v. Input
0.12628 0.123057
p=3.6338E-21
Output v. Distilled p=0.003025001
Table 2 Light Level Testing Statistics
Graph 1 Light Level Testing
0.072353
Salt Water TDS
Mean
Tap: 193.6
Salt: 8820
Output: 48.6
Salt v. Output
p= 1.19927E-14
Tap v. Output
p=1.37422E-08
Table 3 Salt Water TDS Statistics
Graph 2 Salt Water TDS
Graph 4 Pond Water TDS
Graph 3 Pond Water pH
Pond Water pH
Mean
Input v Output
Pond Water TDS
Input: 7.74
Output: 6.8
p= 1.09701E-05
Table 4 Pond Water pH Statistics
Mean
Input v Output
Input: 265.333
Output: 24.667
p=2.28226E-18
Table 5 Pond Water TDS Statistics