| ISEF: Sterilizing Water with Trash! |
| Written by Jozef Winter | ||
| Tuesday, 20 May 2008 | ||
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Access to clean drinking water has been, and will be, a global concern. Even when water is available, sometimes in abundance, it can be unsuitable for drinking due to microbial contamination. This is often the case with river water in Belo Horizonte, Brazil, ioand Veronica Santos and Julia Parreiras have developed a low cost / no cost disinfectn solution for those who use rivers, or other unpotable sources, to obtain their drinking water. The system can be created and assembled using 100% recycled materials, in fact, the entire system is made out of waste. The basic principle is to heat water using a solar concentrator, thereby killing bacteria and making the water safe to drink. Of course you don’t just find solar concentrators every day, so they built, and will teach those in need to build, their own using scrap cardboard and a reflective surface. When I asked if aluminum foil was readily available in rural Brazil, thinking they used that for reflection, they smiled and pointed out that if you turn an empty bag of potato chips inside out, you get a very good reflective device. Their concentrators, made from such crude materials, are very efficient. They have achieved temperatures upwards of 70C, but only need to sustain at least 50C for 4 hours to ensure disinfection. To hold the water they use PET bottles, half painted black in order to absorb more heat, making the process more effective. They chose PET bottles because, from their spectrophotometerical analysis, they afforded more UV transmittance and were thicker, therby extended their usable life. They also found that with some modifications, allowing adjustable reflectors for the concentrator, the total exposure time could be reduced to 2 hours from the original 4, getting potable water to whoever needs it that much faster.
Comments
(5)
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written by RS , May 20, 2008
I´m in love
What leaches into the water...
written by Robert Thille , May 20, 2008
from the PET @ 50C? I'd certainly feel better about glass or metal than plastic, but I guess given the choice between unsterilized and feminizing, I'm not sure which is worse...
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written by DJ Strouse , May 20, 2008
Nothing worse than what'd you have otherwise. Studies show its generally safe:
http://www.sodis.ch/Text2002/T-PETBottles.htm
Congratulations Brazil
written by Marcelo Molina , May 21, 2008
Congratulations to the girls!
Parabens 'as Gurias... Pena que essa noticia nao seja tao divulgada no Brasil... Estou colocando o link no meu blog www.tecnomodo.com
PEV chemicals?
written by Michael Stange , May 22, 2008
Ok, what a wonderful idea, but why don't they use glass bottles? PEV leaches all kinds of dangerous chemicals into water when the bottles are exposed to sunlight, so I would be interested to learn what leaches in with concentrated sunlight. Basically, the bacteria are gone, but cancer and birth defect-causing chemicals intensify. Hmmm...Catch 22 anyone?
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