1. 1

Abstract--This report describes a purification system
beginning at a flowing water source and ending just before
distribution into a village-wide plumbing system. This system, as
is, is capable of providing clean, drinkable water out of the tap for
a large number of households. The Purification Team aims to
design and develop a low-technology, economical, and efficient
method to filter contaminated water and provide rural villages
with a reliable source of clean water. The combination process of
collecting and disinfecting water begins with a water inlet, which
connects to a slow-sand filtration system, and ends at a chamber
where UV-C light will be emitted. Implementing rain harvesting
collectors will take advantage of the six-month long rain season of
Northern Thailand, while the sand filter can remove bigger
particles in the water. Finally, the UV-C radiation will kill
pathogenic bacteria and viruses in the water, turning infected
water to potable water. Our ultimate goal is to put together a
purification system that is feasible to not only one village, but
villages in other parts of Thailand.
Index Terms— E. coli, electrolysis, energy efficient, filter,
potable, slow sand filter, Thailand, UVC filter, water
I. NOMENCLATURE
A nomenclature list, if needed, should precede the
Introduction.
II. INTRODUCTION
URRENTLY, many sources of water in developing
countries in regions such as Southeast Asia and sub-
Saharan Africa are contaminated. In Southeast Asia, the most
common source of contamination in the rural regions is
coliform bacteria. Coliform bacteria are not the only disease-
causing pathogens in water, but presence of coliform bacteria
Financial support should be acknowledged here. Example: This work was
supported in part by the U.S. Department of Commerce under Grant BS123.
The paper title should be in uppercase and lowercase letters, not all
uppercase.
The name and affiliation (including city and country) of each author must
appear on the paper. Full names of authors are preferred in the author line, but
are not required. Initials are used in the affiliation footnotes (see below). Put a
space between authors' initials. Do not use all uppercase for authors'
surnames.
Examples of affiliation footnotes:
J. W. Hagge is with Nebraska Public Power, District Hastings, NE 68902
USA (e-mail: j.hagge@ieee.org).
L. L. Grigsby is with the Department of Electrical Engineering, Auburn
University, Auburn, AL 36849 USA (e-mail: l.grigsby@ieee.org).
in water sources indicates other diseases-causing organisms
may be present. One of the families of coliform bacteria is
fecal coliform group, which is found in intestinal tracts of
warm-blooded animals.[1] Presence of coliform bacteria in
these water sources could indicate the water had been
contaminated with fecal waste. Currently, the sources of water
in the villages of Northern Thailand, namely two specific
villages in the Omkoi District(Chiang Mai Province), Ka Thaw
and Ma Oh Jo, have been tested Escherichia coli positive,
which proves that fecal contaminants exist in their water
source. While some villages are diligent in boiling water their
drinking water, many villagers are uneducated or are unwilling
to spend the necessary effort. Moreover, since the local
schools and other public areas in the villages are poorly
equipped, children often drink water from the tap, which is
from the contaminated water source. This raises concerns
because many diseases can be spread through fecal
transmission: typhoid fever, and hepatitis A. When drinking
contaminated water, one may experience diarrhea, cramps,
nausea, and possibly jaundice.[2]
Our Purification Team aimed to design and develop a
low-technology, economical, and efficient system to villages in
rural region of Northern Thailand with the aim of providing a
reliable source of clean water. When approaching this
problem, the team kept to two basic principles: to be
sustainable and to be economical. We would like to see this
project become the village’s project; such that they are able to
build, maintain, and expand the system as they see fit.
The goal of this report is to present the results of a year and a
half of research and engineering design. In this report, the
Purification Team intends to describe in detail a
comprehensive water treatment system which can be modified
to suit varied circumstances and situations. ITDP (What does
this stand for? Need to add detail on group.) already employs
several of the systems described in this report, and
recommendations will be given to augment or improve the
current systems.
III. PROJECTION DESCRIPTION
A. Existing Solution
The current water filtration system that is implemented has
greatly improved the health and quality of life of villagers who
Water Filtration and Sterilization with Slow
Sand Filter and Ultraviolet – Type C in
Developing Area of Northern Thailand
J. W. Hagge, Senior Member, IEEE, and L. L. Grigsby, Fellow, IEEE
C

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are served by the filtration system. Cases of diarrhea and
malaria, while still major health issues for the villagers, have
been greatly reduced since the water filtration system was
implemented but they have not been totally eliminated.
Samples taken during ESW UCSD’s trip to the village
indicated presence of coliform bacteria in the filtered water.
The village’s system consists of two stages: water input and
water filtration. Water is piped from a water source via simple
mechanical principles to filter to screen out large debris. The
water is then piped down to a slow sand filter which helps to
filter and purify the water. This component is described later in
the report.
B. Statement of Requirements
The two major issues with the current setup are that the
source pre-filter has to be manually cleaned frequently (2-3
times a week during rainy season) and that the slow sand filter
alone is not providing complete water purification. Ease of
maintenance and filter effectiveness are the main aspects of the
system which need to be improved upon. Preventing the water
source from clogging would not only reduce the amount of
time and labor spent maintaining the system, but it would also
increase the amount of water the filter takes in, as water flow
would not be reduced. The current slow sand filters are very
effective at reducing water turbidity (amount of suspended
particles) but do not reduce coliform concentration to
acceptable levels. The system should reduce coliform
concentration such that it cannot be detected with a home
water quality testing kit.
IV. OVERALL DESIGN SOLUTION
****NEED INTRO OF SECTION****
A. Water Intake
The source of water for these villages is the Ping (may be
wrong) river (http://www.mapsofworld.com/thailand/thailand-
river-map.html ). They have a water inlet[3] in a stream fed by
this river which takes the water to their village’s. If the design
of the current dam[4] is improved then there can be less effort
put into maintaining the system[5].
V. DAM
The dam currently in place becomes covered with mud and
other debris during heavy rainfall, and must be manually
cleared several times a week during the rainy season. Having a
dam that encircles the water catchment T[6] would allow
greater control of what enters the water catchment system
while reducing the amount of work needed to maintain
adequate water flow to the filter.
A. Characteristics of the Dam
The dam is composed of four walls, two of which face the
banks[8] of the stream and prevent the erosion of excess
sediment into the system. The other two face upstream and
downstream to allow for water flow into the system. The wall
facing upstream contains a gap which allows for adjustments
of water flow to be made by the placing or removal of sand
bags. The wall facing downstream contains only minor
drainage holes closest to the floor of the system. This ensures a
flow out of sediment at a steady rate as well as a controlled
volume in the dam.
The dam is intended to fill with water so that it contains a
mixture of fresh water and sediment. The water catchment T
will be placed at the proper height within the system and at a
proper distance from the inlet such that sediment will sink well
below it and be flushed out of the system via the drainage
holes in the back wall.
The dam’s foundation will stay in place by a mixture of
anchoring and weight. The dam is intended to be built as a
mini arch-gravity dam[9](Fig. 1) that has a great deal of weight
(translating to lots of mortar and rocks in our case) at its
bottom relative to its top. The wall facing downstream will be
curved into the inflowing water. The front wall should be
designed as in Figure 2 where a cross section looks similar to a
triangle. The lowest part of this triangle represents the part of
the dam of greatest thickness. Each wall can be made
individually and mounted into the ground by burying at least a
third or so of the wall into the ground to prevent it from
drifting away. The walls can then be “glued” together by using
mortar in between the cracks formed by putting them next to
and touching one another.
Fig. 1 ***NEED DESCTIPTION***
Fig. 2 ***NEED DESCTIPTION***
The water catchment T will be placed through the back wall
of the dam and then be led to the slow sand filter. Ideally the
dam should be made so that all water flowing down the stream

3. 3
should pass through it. The length of the inlet and outlet[10]
can be adjusted based on the most feasible width of the stream.
The stream width can be adjusted through proper
consideration of water flow through the stream on average
(especially during the heaviest flow of water).
The dam may be constructed entirely of mortar and due to
shear weight ought to be constructed as furthest up the stream
as possible. A frame can be made and filled with mortar for
each wall (the side walls of the dam will be exactly the same,
whereas the inlet and outlet will require special individual
frames).
B. Benefits and Impacts of the Dam
The benefits of implement the dam in front of the water
intake include:
 Will allow for adjustable water flow using sandbags to
adjust height of front wall of dam. This is ideal for
seasonal variations in rainfall which lead to variations
in river flow and subsequently the water intake of the
system.
 A greater distance between the water catchment system
and the floor of the enclosed dam will ensure less
soot enters the system.
 A sturdy arch-gravity dam design will ensure a lasting
damming system.
 The materials necessary are flexible, allowing for the
use of a variety of materials (like mortar[7] and
rocks).
 Prevents collapsing of dirt around dam walls, leaving
only mud flowing downstream to worry about when
water enters the dam.
Some potential negative impacts of the dam system
include:
 If the water-flow changes too quickly for anyone to add
sandbags the overflow or underflow of water will
cause problems (overflow brings more soot,
underflow brings less water).
 Flow rates are not controlled well, thus there may be
either too little or too much flow of water to keep the
sediment concentration in the system under control.
 Will still require some maintenance from villagers,
who will sometimes need to clean soot buildup in and
around the dam.
VI. SLOW SAND FILTER
A slow sand filter is any kind of water filter which uses a
bed of fine-grained sand as its primary filtration method. In
these filters, the sand acts as a screen to prevent waterborne
particles from flowing past the sand bed. As water flows
through the filter, any microorganisms present in the water are
also trapped in this sand bed. Most raw water sources also
harbor organisms which use other microorganisms, including
pathogens, as a food source. As these pathogen-eating
microorganisms multiply and develop in the sand bed, they
form a bio-layer, also referred to as the Schmutzdecke.[11]
This bio-layer, if properly formed and maintained, can be
effective at removing bacteria, viruses, color, and odor. . This
biological layer forms in the top 5 to 10 cm (active up to
20cm) on the wet sand after allowing the water to flow through
the gravel and sand layer for about 3 or 4 weeks.[12]
The slow sand filter is composed of several layers: (from
top to bottom) fine sand, medium grained sand, gravel, and
large rocks. The sand grains which comprise the top layer
should have an effective diameter of 0.15-0.35mm which
allows for the biolayer to form.[13] Activated charcoal can be
added between the large sand and gravel layer to provide an
additional purification and odor-removal layer.
Fig. 4. Gradient of components in slow sand filter. From top to bottom:
biolayer, fine sand, medium grained sand, gravel, and large rocks.
VII. ULTRAVIOLET LIGHT – TYPE C FILTER
Ultraviolet light is radiation with the wavelength shorter
than the ones of visible light, in the range of 10 nm to 400 nm.
Specifically, ultraviolet type C (UVC) refers to the
electromagnetic waves that fall between the wavelength of 280
nm and 100 nm. Ultraviolet type C effectively destroys nucleic
acids in microorganisms, which in turns disrupts the structure
of DNA. DNA is the genetic material for most

4. 4
microorganisms, and microorganisms pass on this genetic
information by a process called replication. UVC produces
substances called photoproducts, which obstruct the
replication process. Unlike chlorination, using UVC to treat
water has no disinfection byproducts. This prevents
microorganisms from reproducing, and sterilizes contaminated
water.[14] One UVC device, known as UV Waterworks, is
20,000 times more energy efficient than boiling water over a
stove. [15]
Exposure to UVC radiation is harmful to humans, as it is
harmful to microorganisms. UVC can result in skin irritation
and severe eye damage. It is important to take all safety
precautions when operating UVC lamps and to avoid direct
exposure by ensuring closure of UVC chamber when it is
plugged into the power source, regardless of the light is on or
off.
To prevent a microorganism from replicating its DNA, it
must be exposed to a certain amount of radiation – this is
known as fluence. Fluence is calculated as the product of
exposure time, light, and intensity at a given wavelength.14
One can think of fluence as the “dose” of UVC radiation. The
fluence depends on several variables associated with the
operation specifications of the UVC purification device, as
well as the characteristics of the contaminated water. The more
the water in device, the longer exposure time is needed for
similar effects compared to thin layers of water in the same
device.
The recommended specifications for bacterial, viral and
parasite control is between 10 - 12 gallons/watt*hour (12 – 15
liters per hour, per watt). This fluence is considered high
exposure, and this will ensure UV dosage sufficient to prevent
most waterborne diseases[16]. UVC purification effectiveness
is limited by the water’s turbidity, a metric of how much
suspended particulate the water contains. Before going
through the UVC device the water must be filtered to decrease
turbidity. In our system, this is accomplished by the slow sand
filter. If the water has large amount of sediment or suspended
particles, these particles can block the UVC radiation.
A. Set Up of UVC Filter
The UVC filter can be placed after the slow sand filter.
That way, most of the debris and dirt in the water will be
filtered out before entering the UVC chamber. If the water is
murky and dirty, the particles block some of the UVC
radiation, preventing sterilization of the water.
Fig. 5 UVC chamber filter sterilizes water after running through slow sand
filter
One downside to UVC purification is that the lamp must be
periodically replaced. For modern UVC devices, however, this
rating is exceedingly high. UV lamps can be rated up to
20,000hrs before needing to be replaced. Routine cleaning and
inspection conducted once every six months is highly
recommended to ensure smooth operation.
Fig. 6. UVC chamber filter planned to be used in Omkoi District in June 2013
VIII. ELECTROLYSIS
Water purification by electrolysis is not well documented
and an optimal set up for such a system has yet to be seen. The
volume and value of the studies being conducted is
encouraging the development of more efficient and effective
electrolysis systems. As it stands today, however, there is a
lack of consensus on the efficiency of electrolysis systems, and
we recommend alternatives that are much better documented
and have been put into practice.
Electrolysis systems work by inducing an electric potential
difference between two metal plates submerged in water
contained in separate chambers. The potential difference
causes a buildup of excess charge on each plate. Each charged
plate then induces negatively charged anions and positively
charged cations. These charged molecules create a pH
imbalance and react with pathogens suspended in the water,
thus establishing the purification aspect. After a certain
amount of time, the two water chambers are mixed together
and a pH balance is reestablished.
The concept of electrolysis is simple in theory, but slightly
more complex in practice. The plates are specially made for
the purpose of conduction and are made of metals such as

5. 5
aluminum and copper. In various experiments, these plates are
coated with different materials. The effectiveness of the filter
is also dependent on the amount of power that can be provided
over time to the filter. In one study done by the University of
Chile, a 4.9W power supply applied over 90mins resulted in a
90% reduction in the pathogen count. In the few experiments
that have been conducted, there are no results that have
reported the desired 99% pathogen reduction. In the cases
where there are not secure and reliable power supplies, this
can result in anomalous results.
There are several problems which arise in such a system as
well. First, the charged molecules that the plates induce are
mostly found within the vicinity of the plates. Isolated pockets
of unpurified water can be remedied by circulating the water
around the plates. Second, the plates will degrade over time
due to the pH imbalance and plates that are not carefully
treated will do more harm than good to the purification of
water. Aside from requiring regular replacement due to natural
degradation, the metal precipitants from the plates may also
become suspended in the water. Thirdly, the scientific
literature suggests that the purification of the water is
dependent on the voltage and voltage frequency used, the
exposure time, and the amount of water purified. Because of
these factors, there is no clear optimal time-watt-liter ratio to
be certain the water is purified.
Fig. 7 ************ NEEDS DESCPT**
A. Suggestion: Benefits and Impacts of Electrolysis
Some of electrolysis’ characteristics are beneficial for
developing regions. The system is clearly very reusable as long
as the metal plates are well maintained. The water chambers
only have to be mixed to balance the pH levels, though it is not
clear how many uses a typical setup can go through as it is
highly dependent on the quality of the metals used.
The system as a whole is environmentally friendly, as the
only waste produced are the metal plates, which can be
recycled. The system requires no chemicals to function, though
adding electrolytes can help speed the purification process.
However, there are some negative impacts of electrolysis.
Materials to assemble the system are not easy to acquire as the
metal sheets are precisely cut and coated with material.
Another downside is that the system needs a source of power
to run. The effectiveness of the system is also dependent on the
amount of power that a source can provide.
IX. CONCLUSION
A. Dam Suggestion
Landscaping: To avoid potential erosion around either side
of this enclosure, a sloped bed of rock should be made lining
the banks of this diverted stream. Above this bed of rocks, on
the floodplain[17] of the stream, erosion controlling plants
should be planted (trees, shrubs, etc.). The roots of these plants
will help maintain the foundation of the side of the stream, the
rocks will support this as well.
Building: The flow rates of the stream should be considered
when designing the dam’s front wall. For instance, if the flow
rate is sparse for a long period of time, then the wall’s lowest
open point (the point where water may pass into the dam)
should be lowered.
B. Slow Sand Filter Suggestion
The formation of the Schmutzdecke is the most vital
component of the Sand Filter. Typical scenarios that may
prevent the biolayer from forming are: the lack of fine sand to
trap food for the biolayer, a strong water flow that disrupts the
surface of the water, sporadic water flow, and the lack of a
water layer on which the biolayer can rest. It is important that
these problems be mitigated in order that the slow sand filter
can purify the incoming water.
C. UVC Filter Suggestion
The filter must have an adequate power supply so that it can
purify the water effectively. The hydroelectric team has
designed a system that can supply the appropriate voltage and
power requirements. The flow requirements for the UV filter
will not be a problem as flow restrictors will be able to slow a
strong water flow and allow the filter to purify at an optimal
rate. It is recommended that the filter be sheltered from
damage.
D. Electrolysis Suggestion
There is no conceivable way to construct a system that will
effectively purify a constant flow of water. We therefore
recommend that one stray away from implementing an
electrolysis system, but keep the prospect in mind. Despite the
promising future that it has, there is no guarantee that it will
work effectively in the present. The many working systems
such as UV filtration and Slow Sand Filter filtration have been
proven to work and have already been designed effectively.
A primary section heading is enumerated by a Roman
numeral followed by a period and is centered above the text. A
primary heading should be in capital letters.

6. 6
E. Abbreviations and Acronyms
Define less common abbreviations and acronyms the first
time they are used in the text, even after they have been
defined in the abstract. Abbreviations such as IEEE, SI, MKS,
CGS, ac, dc, and rms do not have to be defined. Do not use
abbreviations in the title unless they are unavoidable.
See Appendix A of the Author’s Kit for additional
information and standard abbreviations.
X. APPENDIX
Appendixes, if needed, appear before the acknowledgment.
XI. ACKNOWLEDGMENT
The authors gratefully acknowledge Steve Porter for
allowing us to use their lab space to sift sand for our slow sand
filter prototype; Chris Cassidy from the Design Studio, and the
Urey Hall underground workshop for helping us construct our
UV Filter Demo; Student Sustainability Collective for their
support for student projects.
The authors would like to give a final thanks to Mike Mann,
our contact in Thailand, without whom, all of this would not
be possible.
XII. REFERENCES
[1] Vermont Government. Vermont Department of Health. Coliform
Bacteria in Water. Burlington: , 2011. Web.
<http://healthvermont.gov/enviro/water/coliform.aspx>.
[2] Fresno County Department of Public Health. Environmental Health
Division. E. Coli or Fecal Coliform Bacteria Notice. Fresno. Web.
<http://www.co.fresno.ca.us/uploadedFiles/Departments/Public_Health/
Divisions/EH/content/Water_Surveillance/content/Fecal_Coliform_Noti
ce_-_Private_Wells.pdf>
[3] The front of the dam (facing upstream) where water flows into the
system.
[4] Any structure which slows down the source water so it may be collected
into pipe inlet.
[5] Refers to all components within the dam (water catchment T, sediment,
walls, and water).
[6] The “T” shaped, blue PVC pipe fitting placed in the diverted stream that
collects water.
[7] A mixture of sand, water and cement or lime that is used to fix bricks or
stones to each other when building walls.
[8] The land alongside or sloping down to a river or lake.
[9] An arch dam having also sufficient mass and breadth of base to provide
gravity stability.
[10] The back of the dam (facing downstream) where water flows out of the
system.
[11] Fewster, Eric, Adriaan Mol, and Sheryl Haw. "The BioSandFilter ."
BioSandFilter.org. BushProof, n.d. Web. 2004.
<http://www.biosandfilter.org/biosandfilter/index.php/item/255>.
[12] AWWA Research Foundation, Slow Sand Filtration, June 1991
<http://www.oasisdesign.net/water/treatment/slowsandfilter.htm>
[13] Tech Brief. A National Drinking Water Clearinghouse Fact Sheet, Slow
Sand Filter, June 2000. <
http://www.nesc.wvu.edu/pdf/dw/publications/ontap/2009_tb/slow_san
d_filtration_dwfsom40.pdf>
[14] "Basics of Ultraviolet Disinfection Technology."rael.berkeley.edu. N.p..
Web. 12 Nov 2012. <http://rael.berkeley.edu/sites/default/files/very-old-
site/uvtube/uvdisinfection.htm>
[15] Ashok, Gadgil. "UV Waterworks 2.0." lbl.gov. Indoor Environmental
Program, n.d. Web. June 2012.
[16] Strohmeyer, Carl. "Ultraviolet Sterilization." American Aquarium;
Aquatic Information; Supplies. American Aquarium Products, 27 2012.
Web. June 2012.
[17] An area of low-lying ground adjacent to a river, formed mainly of river
sediments and subjectto flooding
[18]
[19] D. Ebehard and E. Voges, "Digital single sideband detection for
interferometric sensors," presented at the 2nd Int. Conf. Optical Fiber
Sensors, Stuttgart, Germany, 1984.
[20] Process Corp., Framingham, MA. Intranets: Internet technologies
deployed behind the firewall for corporate productivity. Presented at
INET96 Annu. Meeting. [Online]. Available: http://home.process.com/
Intranets/wp2.htp
XIII. BIOGRAPHIES
Wendy Cheung, undergraduate student at the
University of California, San Diego, majoring in
Environmental Engineering.
Erik Hauenstein, undergraduate student at the
University of California, San Diego, majoring in
Environmental Engineering
Peggy Ip, undergraduate student at the University of
California, San Diego, majoring in Mechanical
Engineering
Patrick Charles, undergraduate student at the
University of California, San Diego, majoring in
Mechanical Engineering
Michelle Tang, undergraduate student at the
University of California, San Diego, majoring in
Environmental Engineering.

7. 7
Alexander J. Ty, undergraduate student at the
University of California, San Diego, majoring in
Engineering Physics.