Extracting Pure water From Atmospheric Humidity
Pure water, not only pure but
usable surface water is going to be, or is a big threat to the existing living
system on earth. That is the reason now we are spending considerable amount
of time and money to find an alternate planet with water and other livable
conditions. The scenario may different like, we can migrate to new space or we
can transport water from there to our reservoirs. But my gut feeling is, we
have spent more time to think, how we can reduce the use of water, how we can
avoid wastage of water, and more importantly how we can produce water.
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Production of water from air humidity |
Production of water from atmospheric
air
This is a very hot topic to
discuss and a lot of research and investment is going on this topic. Even in
hot and dry area, there is a lot of moisture available in air. And due to
increasing in global warming, the moisture content in the air is going to more
in future and surface and ground water availability will go down.
This idea will succeed only if
the production cost is nominal and the technology is simple and affordable. In future
our main target is developing a renewable source of water and fuel production.
There are mainly two process
involve in water production from atmospheric air.
1. Absorption
of humidity from air
2. Separation and condensation (desorption)
Absorption of water from atmospheric air
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| Absorption of atmospheric humidity |
In order to make the absorption of the air humidity in the
saline solution as efficient as possible, a large interface with the air and a
long contact time are necessary. This is done by allowing the saline solution
to flow slowly down sorption strings in tower-shaped, naturally ventilated
plant modules and to absorb the water from the air. By means of a special
design of the sorption strings an efficient mass transfer is achieved and the
saline solution is diluted by the substantial absorption of water.
Desorption : distillation and
condensation
The water has to be separated from the circulating saline
solution (desorbed), and so a distillation process follows. The distillation is
effected by means of gravity-assisted, multiple-stage vacuum evaporation. To do
this, the saline solution, diluted with water, is subjected to a vacuum, which
considerably reduces the evaporation temperatures. The advantage of this is
that these temperatures can be achieved with simple solar thermal collectors or
also with waste heat. Since the plant works with a negative pressure, it is
also possible to use the thermal energy employed several times in various
evaporation stages with different pressures. The water vapor produced in the
distillation is condensed and can be used as high-quality drinking water.
A combined tower-construction for the sorption and
desorption makes it possible to use the gravity of the process flows to create
the required vacuum. Energy-intensive vacuum pumps are no longer needed.
This is an exaple of pracal application of the technology Biilsboard that produce water in Peru.
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