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Potable Water From Air

Ateneo is at the forefront of producing water from air.

By Paul Cabacungan (Ateneo M.S. ECE Student)

Water covers 70 percent of our planet. And only 3 percent of that is considered to be fresh water while the remaining is undrinkable salt water. National Geographic cited that even if all the water in rivers, lakes and streams combine, this would only produce 1% of the world’s fresh water. If fresh water is also considered to be a scarce resource then how much more for safe and clean drinking water.

An article in the January 2008 issue of the IEEE Transactions on Industrial Electronics mentioned that 2.4 billion people in the world lack access to safe water.  It is estimated that there are about 1.7 million deaths per year worldwide because of diseases found in poor water quality.  Even the use of chemical treatments such as chlorine in water was scientifically proven to have hazardous side effects if taken excessively.

Remote areas and many provinces in the Philippines do not have access to safe drinking water. Even in cities, potable water is very limited. At times, people have to spend so much just to ensure having good quality drinking water from water purifying companies. Trying to supply people with unlimited safe drinking water is a problem that needs to be addressed fast.

The Ateneo de Manila University Innovation Team composed of faculty members and students are working on a system that can produce water from air alone. The system not only collects water from air, but it is also able to purify the water to make it safe and potable. The stand-alone system runs on solar power which makes it very possible to provide clean water even in remote places where electricity is not available.

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Figure 1. Water from air with filtration and purification.

How does the system work? A dehumidifier is used to collect water from air. Like any air-conditioning unit, the dehumidifier has a compressor inside. Water is produced when the air gets in contact with the compressor’s cold coils. The coils become cold when the compressor puts pressure on the refrigerant.  Initially, the pressure raises the refrigerant’s temperature but the heat exchange in the coils allows the refrigerant to condense and flow through the expansion valve.  As it passes through the expansion valve, the liquid refrigerant moves from high to low-pressure zone. It then evaporates and absorbs heat, thus making the coils cold.

The cold coils produce moisture when air gets in contact with them. This accumulated moisture would now be the water collected from air. With the said dehumidifier, a continuous run of 9 hours produces about 7 liters of water for every 4.7 kilowatt-hour power.

The water then passes through a filtration and purification process to make the water potable.

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Figure 2. The dehumidifier producing both cold and hot water.

The filtration system plans to make use of stones and clays to filter impurities or sediments as water passes through the system. Red clay mixed with dry organic material such as coffee grounds, rice hulls or tea leaves can be used as a catch basin for the water collected. Immediately under the clay is an activated carbon.  The activated carbon is made from coconut shells from the by-products of copra processing. Compared to other materials (such as wood, rice husk or corn cob), the carbon from the coconut shell has the more potent ability to absorb color or unpleasant odor. Tony Flynn of the Australian National University has demonstrated that this type of ceramic filter can remove 96.4 to 99.8 percent of E-coli bacteria.

As for the next stage of purification, the water is passed through ultraviolet light.  UV radiation effectively destroys bacteria, viruses, and cysts found in contaminated water.

Actual water produced has been tested. The bacteriological evaluation of this water conforms to the Philippine National Standards for Drinking Water (PNSDW) conducted by the Biology Department of Ateneo de Manila University, School of Science Engineering.

And finally to make the system stand-alone, a typical car battery is used to power the whole system. And what makes this unique is that the batteries will be charged via solar power through the use of solar panels attached in the system.

Because the Philippines is a tropical country and weather is mostly humid, this condition makes the project very feasible because more water can be produced from the humid air. Even for rainy season, the system is very flexible that it can directly get rain water and use the same filtration and purification system to produce clean potable water.

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Figure 3. A solar panel is testied to measure its power output.

Topic revision: r2 - 03 Sep 2008 - 11:01:17 - BearTiu
 
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