Desalination provide us fresh water. The natural process
Desalination of water can be undertaken by using any of the two known processes namely distillation and filtration . Both these processes eventually result in the purification of the original source of water. Mother Nature too relies on desalination to provide us fresh water. The natural process of evaporation, condensation, saturation and precipitation which gives us rain is a classic example of the nature’s distillation process. Yet another process of desalination as seen in nature is the filtration process that helps in maintaining the ground water table by multi-stage permeation filtration.
These processes in the nature have been understood and used by man, as early as the 1600s when sailors boiled seawater to produce freshwater to meet their drinking water requirements. The world’s first commercial traditional distillation plant called Tigne was built in Sleima, Malta in 1881 with the first land-based plant being built in 1928 at Curacao, Netherlands Antilles. Since then, various technologies have been developed, see Figure 1, and tried out. The motivation behind these developments has been to be able to cost effectively produce fresh water as it is the only rain-independent fresh water source for human beings. Today, over 16,000 desalination plants, both big and small, exist in the world.The major problem with these desalination plants is the fact that the cost of the fresh water produced is much higher, due to the use of power to run these plants, than that spent in recovering ground water.
However, with limited alternatives available, desalination on land using sea water is the only available option for mankind. Currently, over one billion people (around 1 per cent of the world’s population) lack access to fresh water and an additional 2.7 billion face scarcity that lasts for at least one month a year . According to the UN projections , by 2030, the world’s demand for freshwater will exceed the supply by 40 per cent leading to nearly 14 per cent of the world’s population to encounter water scarcity, which is going to become even more severe due to rising sea levels caused by climate change and extreme weather.