Student's six-foot water and solar-powered lens purifies polluted water

Aug 15, 2014 by Marcene Robinson
Student’s six-foot water and solar-powered lens purifies polluted water
Deshawn Henry working on the water lens that can heat a liter of water to between 130 and 150 degrees Fahrenheit in a little more than an hour, destroying 99.9 percent of bacteria and pathogens.

(Phys.org) —Water may appear to be an abundant resource, but in some parts of the world clean water is hard to come by.

That could change through the work of Deshawn Henry, a University at Buffalo sophomore civil engineering major, who researched how to improve a 6-foot-tall, self-sustaining magnifying glass.

Properly termed a water lens, the device uses another abundant resource—sunlight—to heat and disinfect . Since the frame for the lens can be constructed from commonly found materials—wood, plastic sheeting and water—the lens can be built for almost no cost, offering an inexpensive method to treat water.

The device may not look like much, but it can heat a liter of water to between 130 and 150 degrees Fahrenheit in a little more than an hour, destroying 99.9 percent of bacteria and pathogens.

"The water lens could have a huge impact in developing countries," says Henry, a Queens' native who performed the study under James Jensen, professor in the Department of Civil, Structural and Environmental Engineering.

"Millions of people die every year from diseases and pathogens found in unclean water, and they can't help it because that's all they have. Either they drink it or they die."

The lens consists of a plastic sheet covered with water supported by a wooden frame. The frame holds a small container of water below the lens in line with a focal point created from a concentrated ray of sunlight. Barring the weather, once assembled, the lens functions freely. Due to the sun's movement throughout the day, Henry needs to repeatedly shift the container to match the .

Henry's research tested how altering the thickness of the plastic sheet and the volume of water over the sheet affected the efficiency of the lens. The device was tested with that were 0.7, 1 and 2 millimeters thick, and water volumes of four, six and eight liters.

The study found that adding more water to the lens improved efficiency, as larger areas of water transmitted more energy from sunlight. However, thicker plastic sheets consumed more energy from light, lowering the lens' efficiency.

A plastic sheet that was too thin or excessive amounts of water could break the lens. Henry concluded that the 0.7-millimeter sheet could efficiently heat the container while supporting eight liters of water, but any more and the sheet could potentially break.

With 1.1 billion people lacking access to clean drinking water, Henry's work could make a difference in the world, says Jensen, who frequently mentors undergraduate students during summer research programs.

Henry studied under Jensen through the UB Louis Stokes Alliance for Minority Participation (LSAMP) program, which connects underrepresented students with research opportunities in STEM fields. LSAMP is one of many programs in the Office of Undergraduate Education focused on increasing experiential-learning opportunities for students.

"I have seen how intense research activities can inspire UB students and educate the next generation of innovators," says Jensen. "Deshawn's work would allow a family in sunny regions to treat drinking water without having to expend energy or rely on imported technologies."

Building a larger water lens that remains efficient is the next step in Henry's research. A family of five would need a at least three times the size of the device he constructed, which was designed to heat one liter of at a time, says Henry.

Explore further: Pioneering method for water purification

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User comments : 9

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bearly
4 / 5 (1) Aug 15, 2014
A Fresnel lens from an old rear projection TV will do the same ,only better, as demonstrated on the doomsday preppers TV show.
EnergySage
1 / 5 (2) Aug 15, 2014
A solar-powered lens that's able to purify polluted water is only one example of the potential of solar energy. There are so many new innovations in the solar industry out there that it can be difficult knowing when to invest in solar energy. Fact is, solar is here now and it could save you on electricity costs and earn you annual returns. Read more for help on deciding when to go solar. http://bit.ly/Z3KxzF
tadchem
not rated yet Aug 15, 2014
I see a rigid frame. In 1 hour the sun's angle changes 15 degrees, so the objective lens should track the sun with an equatorial drive of some sort (ask any telescope enthusiast).
Actually, a lens is overkill. A solar oven could do the same with less expense. Line a box with aluminum foil and surround it with reflectors to gather more sunlight into the box, which should have a transparent clover to make a greenhouse.
max_gabreski
1 / 5 (2) Aug 15, 2014
Yes, as said above, a solar oven would be much more efficient.
Anyway, heating polluted water up to roughly only 55 - 65 °C (130 - 150 F) will not purify it. I would not dare drinking water supposedly "cleaned" this way.

If you don't want to use chemicals, you must at the very minimum boil it (212 F) during a sufficient time to be sure to eliminate all the micro organisms. And this won't even eliminate other kinds of pollutants such as chemicals, and particularly those absorbed by the water when heating it in a plastic "bag".

Once again, a hoax to promote solar, by people who should learn how to produce drinkable water before building this particularly useless device that may just poison people.
max_gabreski
1.5 / 5 (2) Aug 15, 2014
I need to withdraw my comment on "the chemicals absorbed by water when heating it in a plastic bag". Apparently, only the water lens is made of plastic. Anyway, that doesn't make this device less useless. Boiling the water on a simple fire would be better.
And also, building decent sewage. Worldwide, diarrheal diseases caused by poor sanitation and unsafe water kill around 1.4 million children a year, more than AIDS, malaria and measles combined, and in most cases, this is directly linked to the lack of a proper sewage.
Mike_Massen
5 / 5 (1) Aug 16, 2014
There are many toxins from bacterial waste which is not denatured by these devices, eg Staph Aureus which is a commensal (on the body) if on food or in water generates toxins harmful to health. ie You can eat the bacteria in the millions with no problems but not be immune to its waste products.

Other bacteria such as Salmonella are much more pathogenic eg as little as 100 can cause infection and serious illness but are easily killed by these devices even as low as ~70 deg C.

Unfortunately, there are also 'spore forming' bacteria as well which need temps of ~130 deg C to be destroyed - hence products such as UHT milk etc to handle these...

At least these solar devices improve awareness but are not a complete solution by any means.
amoore_az
not rated yet Aug 16, 2014
Funny this YouTube video from 2011 shows a similar design used to burn wood and heat a pan with water in it. The design is very similar. Maybe some credit should be given.

http://youtu.be/eeSyHgO5fmQ
sdrfz
5 / 5 (1) Aug 16, 2014

Not every primitive community has access to firewood for boiling water, and collecting firewood sometimes requires considerable effort that may not be practical when you've also got crops and animals to tend. This contraption allows people to treat water with virtually no effort to allow them to focus their daily efforts elsewhere.
Lex Talonis
Aug 18, 2014
This comment has been removed by a moderator.
rockwolf1000
3 / 5 (2) Aug 18, 2014
METRIC - METRIC - METRIC - you STUPID American idiots.

95% of the ENTIRE worlds population, is outside of the USA - and we ALL use METRIC, not fucking imperial.

You dumb cunts.


Aww. Lexy is having another fit because he is illiterate in imperial measures.

I'm pretty sure Phys.org wants to change to metric but they aren't because it's so much fun to read Lexy's tantrum's where he shows his ignorance in not being able to use the units most commonly used by Phys.org's main target market - USA.

Here you go dumb dumb:
130 - 150°F = 54.4 - 65.5°C

Now go ask mommy for a tissue to wipe your tears away. Maybe she will offer you some cocoa.

Surely there must be a European science blog you can go read where all the units are in Metric no?

If not, blame those stupid Europeans and their silly 4 syllable measuring lexicon.

Retard.

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