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Clean water for troubled regions

In 2010, more than 884 million people worldwide did not have access to safe drinking water. Water-borne illnesses such as dysentery, e-coli and rotavirus infections are the largest environmental threat to children and infants in the developing world, claiming the lives of about two million children every year. This picture is further complicated when natural disasters strike or conflict breaks out. Water purification with ultraviolet (UV) light is one of the most efficient sanitary methods for eliminating viruses and bacteria in drinking water and could help drastically reduce the number of deaths. Yet until recently, conventional UV purification methods remained unsuitable for use in the world's poorest regions, where clean water is most needed.

The main reason is that UV purification plants require large-scale investments in their construction and operation. Not to mention trained personnel and elaborate water pump systems that expose water to UV light evenly.

Dating back to the early 1900s, UV water purification is the newest and most effective of the three main methods for removing pathogens from drinking water. The other two methods are boiling the water and adding chlorine bleach. Boiling the water before ingestion is by far the oldest method, first documented in Sanskrit writings dating back as early as 2 000 BC. It remains the main method of water purification in the world today, used by an estimated 500 million people in China alone. On the flipside, it is an alarming cause of deforestation and greenhouse gases.

A solution to the problem of our time?

With its low-cost and easy-to-implement portable UV water purification system, European Inventor Award nominees Ashok Gadgil's and Vikas Garud's UV water disinfection device offers a cost-effective, easy-to-use solution for water purification that holds the potential to be a key tool in combating one of the most troubling problems of our time: access to safe drinking water.

The importance of water is highlighted by non-profit organisation The Water Project, which views access to clean drinking water as the foundation of all development. It identifies a lack of access as one of the greatest causes of poverty in Africa. This view is echoed in the United Nations' World Water Development Report 3, which states that history shows a strong link between economic development and water resources.

Clean water, where it most needed

Introduced in 1996 under the name UV Waterworks, the water purification system invented by Ashok Gadgil -- a senior scientist at the Lawrence Berkeley National Laboratory -- and his assistant Vikas Garud, weighs only 15 pounds. It is roughly the same size as a microwave oven and disinfects water using an energy-efficient 40 watt UV light bulb at a rate of 1 000 litres of water per hour. It can be used outside of electrical grids by using a car battery or a small photovoltaic panel for power.

The cost/performance-ratio of UV Waterworks is impressive: Using about 20 000 times less energy than boiling water, one UV Waterworks unit can clean about 16 litres of water per minute for less than €0.01. The system had its successful jump-start during hurricane relief efforts in the Caribbean in 1998 and proved successful in providing clean water to survivors throughout tsunami-stricken areas of Sri Lanka following the infamous earthquake and related tsunami that struck Asia in December 2004. By 2010, the technology had already been installed in more than ten countries worldwide, delivering clean water to over two million people.

"Zapping" pathogens with light

Ashok Gadgil began re-examining the potential of UV light in 1992, whilst pondering how he could come up with a compact and energy-efficient solution to the catastrophic water-shortages that are common in his native country India.

The use of UV light as a method of sterilisation had been introduced by American scientist John Keys in 1919, who patented a UV steriliser to kill germs in water or milk. It relies on submerging a UV lamp, surrounded by a quartz casing for protection, into the liquid in order to guarantee complete and even disinfection.

The invention makes use of a basic biochemical principle: Ultraviolet (UV) light consists of electromagnetic radiation in the range 10 nm to 400 nm, a wavelength shorter than visible light.  Aimed at health hazards such as viruses or bacteria for short intervals - about 12 seconds - UV light damages their DNA, rendering them unable to replicate and infect their human hosts.

Other inventors improved on the method, including Charles Pole with an intricate system of radial water tubes and light reflectors to evenly expose water to UV light, patented in 1921. But all UV systems exhibited one major flaw: Because the UV lamps are submerged into the liquid, their casing collects organic and chemical residue over time. This requires (costly) maintenance on a regular basis and may even prove a health hazard in itself.

By placing the UV lamp above a water-filled treatment tray, the two inventors solved the problem of residue build-up and regular maintenance. What's more: their design also uses gravity and a carefully planned hydraulics design to ensure even water flow, eliminating the need for a pump system.

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