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SOLWA (SOLar WAter)
Introduction

SOLWA (SOLar WAter) solar still consists in a new system of producing drinkable water from the desalination of waters with elevated salt concentration or polluted waters, with the sole use of solar power. In recent years public opinion has become more aware of environmental issues, of the scarcity of environmental resources and of the necessity to guarantee their best use. Environmental resources are no longer perceived as renewable and inexhaustive, but as assets that are, at the same time, insufficient and fundamental to life, and requiring particular care for their management and use. Certainly, water is one of the fundamental assets at risk.

Water pollution and water scarcity do not only entail problems for human consumption, but they have also created usage of low quality water irrigation in many barren areas. The use of qualitatively insufficient waters creates a decrease of agricultural production and causes damages to the atmosphere, the ground and the aquifers [Thameur 2003]. The second global report by the United Nations on the promotion of water resources evidences that nearly one inhabitant of the planet in five has no access to drinkable water and that 40% of the world-wide population do not have a basic service of water depuration. In the course of the 20th century, water consumption increased sixfold, whilst world-wide population only increased threefold.

The barren and desert zones in the world are today facing huge issues due to an increase of desertification. This phenomenon, characterized by the decrease of the water table levels and by an increase of the salts contained, leads to the demise of life forms present within [National Academy of Sciences 1973]. At the same time, these regions present a high energy potential from the sun, which can probably be the best resource for their development, as S. Galal and A.A. Husseiny have noted. During the last few years, water desalination has compensated for these problems by supplying drinkable waters at decreasing costs and developing ever efficient technologies. Among these desalination technologies, some suggest an “environmentally friendly” approach. In particular, ever efficient and productive models of solar still have been realized simulating the natural water cycle. The solar still called SOLWA strengthens some aspects of this cycle, in particular water evaporation and condensation.

The SOLWA solar still helps solving the problem of the scarcity of drinkable water for populations living in poor areas. It helps producing discreet amounts of drinkable water starting from polluted waters, from waters that are not fit for human consumption or from waters with elevated salinity, like sea water.

Unlike other methods currently in commerce, this technology employs solar energy as its only source. Its characteristics avoid corrosion and require only low quantity of labor. Moreover, the solar still can be easily moved and located in any territory with certain characteristics, subject only to the presence of the sun. The solar still has a very contained cost of installation (approximately 50 €/m2), and does not require additional costs, thus satisfying day-to-day human requirements of good quality water.

The SOLWA helps solving an issue of primary importance for human development, such as water supply, even in areas not provided with normal connections to traditional energy resources. It can be installed in any tropical and equatorial territory.