Preliminary Design Review
Senior Design Project 2003
Professor Anderson
Piseth Toch
Joel Patruno
Neusa Veiga
ndubuisi nduaguba
Many of us today are not aware of a major problem that plagues people around
the world. We Americans have such a readily accessible source of clean water that we
take it for granted. Many third world countries have little or no access to clean drinkable
water which leads to high infant mortality rates and lower life expectancies. In many
cases, purification of water is unattainable because there simply is not a source of energy
or many manual purification techniques are just too expensive. The goal of our project is
to produce a water purification system that uses the energy from the sun to implement
proven techniques which can reduce and eliminate dangerous microorganisms and
viruses. We plan to develop a system such that we can purify one gallon of water in one
day. This sounds like a small amount of water however this model can be scaled up to
produce hundreds of gallons a day, which is enough for a family to survive and perform
everyday activities.
There are a myriad of ways to disinfect water. Some of which are better than
others. The easiest and most common way to treat water is to simply boil it. However this
requires a heat source and expends a lot of energy. This technique also produces a limited
amount of water depending on how it is scaled. Also, we could have a large tank of water
but it would take forever to heat up, and we could have small amounts of water but that
would take also a long time to produce the same amount of water.
Another way to disinfect water is to use chemicals such as iodine or chlorine
through a process known as chlorination. The main advantage chlorination is that mass
amounts of water can be treated for a very little amount of money. This is of course
assuming you have the proper equipment and infrastructure to support the process, which
can be a disadvantage. This is why Americans have good access to clean water. Poor
countries on the other hand are not able to treat their water in the fashion we do. Another
disadvantage to chlorination is that it changes the chemical composition of the water and
leaves a taste to the water. If chlorination isn’t done properly it can actually become
dangerous to those drinking it.
The latest technique in water purification is ultraviolet radiation. By exposing
bacteria and viruses to a simple UV light we can kill them or modify their DNA enough
to the point that they become harmless. The advantage to UV radiation is that it is not an
extremely difficult technique to implement. The process can sanitize water in mass
amounts and overexposure does not change the water, leaving it safe for consumption.
The disadvantage to UV radiation, however, is that if the water isn’t used within a few
days some bacteria that haven’t been killed may regenerate and infect the water again.
Also UV radiation only works in a specific range of UV wavelengths, those being
between 230nm and 280nm. Only germicidal mercury lamps can effectively produce
these wavelengths. These lamps themselves have to be treated with care because they can
pollute the environment. Ultraviolet radiation becomes ineffective if the water is turbid.
The bacteria and microorganisms, many on the scale of microns, can hide behind the
much larger particulate in the water and actually dodge the UV rays.
Our idea is to implement a system where we can utilize at least two techniques of
water purification which makes the system efficient, easy to use, and most importantly
produces clean drinkable water. Our current strategy is to implement physical filtration
and further disinfect with UV radiation. Plans to use chemical disinfection are also still
up in the air.
Our main plan of action is to use a sun tracking solar panel from last years design
project to provide power to an ultraviolet light. Stages before UV radiation include a prefiltering process using physical filters to remove turbidity and improve ultraviolet
effectiveness. From there we have to create a control system which ensures proper
exposure to the UV light. Once we have clean water we need to ensure there is no cross
contamination of clean water with dirty water. This all has to be done with a limited
source of power because the solar panel generates about 1.9 amp hours during an eight
hour period of full sun exposure. The system therefore has to be extremely efficient and
self balancing meaning the amount of power available has to be proportional to the
amount of clean water that can be produced. Attached is a preliminary diagram of our
anticipated design.
To review, our product specifications are as follows:
-
The system must be standalone where the user can introduce water, from a river
for example, and simply walk away.
The system utilizes only solar power.
The system must produce one (1) gallon of water during an eight hour period of
sunlight.
The system must be designed with low maintenance in mind.
The system must prevent cross contamination.
The system must use its power wisely so as to not use more power than available.
The system must have target maintenance free period of 2 years.