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Since spring 2010, the dwellers of the village Rema have access to disinfected water.

Sodis method: within 6 hours, UV rays and heat kill 99.9 percent of all pathogens, Lombok / Indonesia.

The Trunz Water Systems cleans 900 liters per hour and draws its energy from solar panels or windmills.

With Cell Membrane Electrolysis a chemically generated acid kills all disease-causing germs.

Nedap Naiade water purifier with integrated solar panel, here in Brazil.

Electrically generated disinfectant rays by Osram deliver up to 80 liters of clean drinking water per hour.

Clean water – a human right

At the beginning of the twenty-first century, every seventh person throughout the world must continue to live without sanitary drinking water. Affected are mainly the peripheral areas in developing countries. At the same time, an entire series of technologies are available to allow these people, too, access to clean water.


The UN Secretary Generals agree. In 2006, Kofi Annan said: "Access to clean water is a central human need and thereby a human right," and his successor Ban Ki-moon doubled that in 2010: "Clean drinking water is decisive for people's survival, health, and dignity." The urgency of this verdict is well founded: 1.8 million people die from diarrhea every year; the majority is children in developing countries.
The UN is therefore determined to cut in half the number of people without access to drinking water by 2015. According to prognoses, however, mainly urban settlements—thanks to connections to mains networks—will profit, whereby many rural areas will continue to be cut off from clean water in the future.
Yet that does not have to be the case. Research and industry have meanwhile developed an entire palette of water sterilization technologies that are especially qualified for use in remote regions. Common to all these facilities is that they have low running costs, can be maintained without a great deal of effort, and are simple to operate. The greatest differences between the individual solutions are in the principles used for sterilization and capacity.

UV rays
The simplest technique for disinfecting water was developed by the Swiss Federal Institute of Technology Zurich. The Sodis Method (Solar Water Disinfection) requires only a plastic PET bottle, heat, and sunlight as resources. The bottle is filled with contaminated water and set outside in the sun for six hours. In this time, the UV rays in combination with the high temperatures reached inside the bottles kill 99.9 percent of the pathogens. Recommended by WHO, Unicef, and IKRK, the method has already been employed in numerous developing countries. The advantage: Sodis costs nothing, works without installation or additional technology, requires no electrical energy, and can be employed as needed without limits. Disadvantages: due to the low capacity, Sodis can supply only the needs of individuals. During the rainy period the method does not work or only with limitations. (www.sodis.ch)
The water disinfection method developed by Osram likewise works with UV rays. However, free sunlight is not at the base of the procedure, but a disinfection radiator operated with 12 or 230 volts that is put into tanks with polluted water. The UV light emitted by the radiator kills the germs and delivers eighty liters of clean water per hour. Advantage: an easily transportable and simple to use system. Disadvantage: the disinfection radiator is reliant on an electrical network to charge the batteries or must be run on electricity. (www.osram.ch/_global/pdf/osram_de/produkte/leuchten/leuchten/sonderleuchten/puritec_de.pdf)
A third technique based on UV comes from Naiade. The company has developed a compact device with an ultraviolet lamp inside that disinfects contaminated water. The necessary energy comes from an integrated solar panel. The Naiade system has been tested by the internationally active certification company Kiwa and the Unesco Institute for Water Education, and is employed in numerous developing countries. It, too, delivers eighty liters of clean water per hour. Advantage: simple maintenance and independence from the electricity network together with its performance render the device suitable for use in small settlements and schools. (www.safe-drinkingwater.com)

Filter
The firm Trunz Water Systems builds both stationary and mobile water preparation facilities with a capacity of 900 liters per hour. The technology is thereby suitable for entire villages. The basis for disinfection is a three-part filter that in a first step removes larger dirt particles, and in the following steps, kills viruses and bacteria (by means of so-called reverse osmosis). The facility draws its energy from solar panels or windmills, whereby a battery guarantees independent operation for up to twenty-four hours. Advantage: qualitatively high-class building components promise longevity and low maintenance costs. In contrast to all of the other techniques, the Trunz facilities are also capable of removing inorganic particles from the water. Disadvantage: comparably high initial investment costs. (www.trunz.ch)

Cell Membrane Electrolysis
The method of water sterilization developed by the firm LVPG is based on so-called Cell Membrane Electrolysis (CME). Contaminated water is mixed with salt while adding electricity at the same time. The resulting chemical reaction produces acid. This acid has strong disinfectant qualities and kills all of the disease-causing germs. After successful disinfection, it returns to its initial components—water and salt. LVPG's facilities meet WHO standards and are suitable for use in industrial areas, for example, the Frankfurt Airport, as well as in developing areas, for example, Ethiopia (see box). Advantage: CME technology delivers disinfected water within seconds. There are no detrimental secondary or end products. Disadvantage: relatively complicated technology. (www.lvpg-international.de/)

Christian Schmidt is a scientific journalist in Zurich.



Rema, a village in a remote area of Ethiopia, has been one of the most important working areas of the Solar Energy Foundation since 2005. While at first the main concern was to supply electricity to the 4500 inhabitants, the foundation soon added the task of supplying the people with clean water. This goal has now been realized. In spring 2010, the firm LVPG brought one of its facilities and installed it in Rema. Village dwellers have since had access to clean water. The water is stored in a central tank and then pumped to individual collection stations. The facility has a capacity of up to 100,000 liters in 24 hours. "For the village dwellers, the clean water signifies a clear improvement in their quality of life," says Harald Schützeichel, founder and CEO of the Solar Energy Foundation.



Source: sun-connect 4 | November 2010 (p. 10-11)

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