23-06-2012, 12:16 PM
TEN YEARS OF SOLAR DISTILLATION APPLICATION ALONG THE U.S.-MEXICO BORDER
[attachment=25207]
ABSTRACT
For the past decade, solar distillation has been introduced
and applied as an option for household drinking water for
several colonias communities along both sides of the U.S.-
Mexico border. Purifying water through distillation is a
simple yet effective means of providing drinking water in
a reliable and cost-effective manner. Solar stills
effectively eliminate all water borne pathogens, salts, and
heavy metals. Solar distillation produces an ultrapure
water that is superior to most commercial bottled water
sources. Three organizations have been active in
promoting the use and development of solar distillation on
the Border, namely the El Paso Solar Energy Association.
INTRODUCTION
The arid U.S. Mexico Border faces serious water supply
issues that are comparable to those found in many parts of
the developing world. There is one leading solar energy
technology in particular that can literally revolutionize
water quality throughout the less developed world with
widespread adoption: solar distillation. This technology
not only purifies water sources, but also effectively
desalinates.
CAPABILITIES
A solar still operates using the basic principles of
evaporation and condensation. The contaminated feed
water goes into the still and the sun's rays penetrate a glass
surface causing the water to heat up through the
greenhouse effect and subsequently evaporate. When the
water evaporates inside the still, it leaves all contaminants
and microbes behind in the basin. The evaporated and now
purified water condenses on the underside of the glass and
runs into a collection trough and than into an enclosed
container. In this process the salts and microbes that were
in the original feed water are left behind. Additional water
fed into the still flushes out concentrated waste from the
basin to avoid excessive salt build-up from the evaporated
salts.
BORDERLANDS SOLAR STILL EVOLUTION
Solar still technology has gradually improved over the past
decade along the Border. The greatest problem for the first
generation stills designed by EPSEA in the mid-1990’s (an
improvement on the original McCracken solar still) was that
when they dried out, the inner membrane silicone lining
would outgas. This in turn deposited a fine film on the
underside of the glass, causing the water droplets to bead up
and fall back into the basin rather than trickle down the glass
to the collection trough and thus still water production drops
dramatically (about 80% or more drop). The first still used a
food grade silicone and were made out of plywood and
concrete siding. It was found that the stills (3’ x 8’) were
often producing far more water than the users needed,
especially in the summer.
CONCLUSIONS
Clean drinking water remains one of the most challenging
international health issues of today, and solar distillation
offers important and effective solutions in meeting potable
water needs. Low cost solar stills offer an immediate and
effective solution in reliably providing safe drinking water
year after year. Single-basin solar stills are easy to build,
inexpensive and extremely effective in distilling water with
a high total dissolved salt content and in killing bacteria such
as cholera and E. Coli.
[attachment=25207]
ABSTRACT
For the past decade, solar distillation has been introduced
and applied as an option for household drinking water for
several colonias communities along both sides of the U.S.-
Mexico border. Purifying water through distillation is a
simple yet effective means of providing drinking water in
a reliable and cost-effective manner. Solar stills
effectively eliminate all water borne pathogens, salts, and
heavy metals. Solar distillation produces an ultrapure
water that is superior to most commercial bottled water
sources. Three organizations have been active in
promoting the use and development of solar distillation on
the Border, namely the El Paso Solar Energy Association.
INTRODUCTION
The arid U.S. Mexico Border faces serious water supply
issues that are comparable to those found in many parts of
the developing world. There is one leading solar energy
technology in particular that can literally revolutionize
water quality throughout the less developed world with
widespread adoption: solar distillation. This technology
not only purifies water sources, but also effectively
desalinates.
CAPABILITIES
A solar still operates using the basic principles of
evaporation and condensation. The contaminated feed
water goes into the still and the sun's rays penetrate a glass
surface causing the water to heat up through the
greenhouse effect and subsequently evaporate. When the
water evaporates inside the still, it leaves all contaminants
and microbes behind in the basin. The evaporated and now
purified water condenses on the underside of the glass and
runs into a collection trough and than into an enclosed
container. In this process the salts and microbes that were
in the original feed water are left behind. Additional water
fed into the still flushes out concentrated waste from the
basin to avoid excessive salt build-up from the evaporated
salts.
BORDERLANDS SOLAR STILL EVOLUTION
Solar still technology has gradually improved over the past
decade along the Border. The greatest problem for the first
generation stills designed by EPSEA in the mid-1990’s (an
improvement on the original McCracken solar still) was that
when they dried out, the inner membrane silicone lining
would outgas. This in turn deposited a fine film on the
underside of the glass, causing the water droplets to bead up
and fall back into the basin rather than trickle down the glass
to the collection trough and thus still water production drops
dramatically (about 80% or more drop). The first still used a
food grade silicone and were made out of plywood and
concrete siding. It was found that the stills (3’ x 8’) were
often producing far more water than the users needed,
especially in the summer.
CONCLUSIONS
Clean drinking water remains one of the most challenging
international health issues of today, and solar distillation
offers important and effective solutions in meeting potable
water needs. Low cost solar stills offer an immediate and
effective solution in reliably providing safe drinking water
year after year. Single-basin solar stills are easy to build,
inexpensive and extremely effective in distilling water with
a high total dissolved salt content and in killing bacteria such
as cholera and E. Coli.