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  Safe water from SODIS and SPOWTS

Two environmentally-soulful, low-cost technologies —SODIS and SPOWTS—are capable of producing safe drinking water from polluted water sources in remote areas. Both deliver sharp slaps on the notion of safe water having to come in priced bottles that are thrown away as litter.

For those of us, now made forgetful by electric UV-treated water units in our homes, here’s a quick primer on ultra violet rays [UV] and Ozone. The sun constantly radiates UV light, which if it enters the atmosphere unrestrained, is harmful to life. But luckily we have the ozone layer in the stratosphere. Ozone is a highly reactive form of oxygen and is equally destructive to life forms in large quantities. However, when UV meets the ozone layer, most of the former is blocked and absorbed. Which by the way, is the reason why we need an intact ozone layer. The purpose of this primer is to remind ourselves that diffused UV is everywhere around us in nature. When polluted water is exposed to UV or made to interact with ozone, harmful micro life forms are destroyed.

The Solar Water Disinfection Process [SODIS], a Swiss innovation, is simplicity itself. Polluted water is prepared for treatment by nominal filtering for sediments. Discarded plastic bottles are cleaned, partially filled with water that is to be treated and shaken vigorously, in order to oxygenate it. The bottles are then filled fully, closed and placed in full sunlight for between 6 and 8 hours. The combination of heat and oxygen-UV interaction kills all pathogens, rendering water safe for drinking.

Obviously SODIS works best in sunny climes— which are also places where safe drinking water is a concern. The process is helped by placement of a black sheet under the bottle to enhance heating. Also, PET bottles are better than PVC ones. It must be remembered chemical, toxic pollutants are not removed by this process.

SODIS is becoming popular in South America, Thailand and Kenya. In Kenya for example, people took quickly to the idea because their tradition was to wash and sun-dry utensils. Goes to show that when we go close to ‘native-ways’, a lot of good sense is revealed.

You will find detailed practical help with the SODIS process at its official site. It is also worth browsing the links to gain an idea of SODIS’s potential.

Solar Powered Ozone Water Treatment Systems [SPOWTS] is technologicaly a couple of notches higher than SODIS, but still quite friendly to use. It was introduced in Nepal by those concerned by the litter of empty water bottles that trekkers leave behind. Also, as trekkers found branded, bottled water more pricey as they moved away from market towns there was an economic opportunity that could lead to micro businesses.

A SPOWTS installation consists of a solar photovoltaic panel driving a 1gm/hour ozone generator. Water to be treated is circulated by a small electric pump and made to interact with controlled dosages of ozone.

Sagarmatha Pollution Control Committee has estimated that 11,508 litres of kerosene and 125,272 kg of firewood were used by organized Everest expeditions in 1996, equating to 256 tonnes of CO2 to make polluted water safe for drinking. SPOWTS is targeted to be a solution to this problem. It was developed in New Zealand by Empower Consultants and manufactured by Lotus Energy in Nepal and implemented by Himalayan Light Foundation. The whole exercise has been co-ordinated by Annapurna Conservation Area Program. So far 16 SPOWTS installations have come up in remote areas. Trekkers quite happily patronise these micro businesses. Empty water bottles are recycled and money stays in the village.

SODIS and SPOWTS are worth the consideration of organisations involved in development initiatives.