Article courtesy of India Current Affairs | November 9, 2009 | Shared as educational material only
The National Institute of Ocean Technology (NIOT) an autonomous body of the Ministry of Earth Sciences has indigenously designed developed and demonstrated desalination technology for conversion of sea water into potable water based on Low Temperature Thermal Desalination System (LTTD). The LTTD is a process under which the warm surface sea water is flash evaporated at low pressure and the vapour is condensed with cold deep sea water. This technology is efficient and suitable for island territories of India.
The initial estimated cost of production of Kavaratti Plant was 10 paise per litre depending on the charges of power/electricity. The estimated cost of production of demonstration plant is inclusive of capital and other fixed costs. The operational cost of production is about 6-7 paise per liter.
Water news regarding seawater converted to potable water:
Siemens turns seawater into drinking water for half the energy:
Article courtesy of greenbang.com | July 4, 2011 | Shared as educational material only
Having completed early tests of an energy-saving method for turning saltwater into clean drinking water, Siemens is preparing to take its technology to the product development phase.
The technology, which uses half as much energy as other desalination processes, was tested at a demonstration plant built in Singapore. Siemens now plans to set up a full-scale system in cooperation with Singapore’s national water agency PUB by 2013.
Singapore, an island nation, is one of many parts of the world in which seawater is becoming an increasingly important source of drinking water. However, desalination is an extremely energy-intensive process.
“Our new technology marks a revolution in seawater desalination,” said Ruediger Knauf, vice president of Siemens Water Technologies’ Global R&D. “The results of our pilot facility show that the new process not only functions in the laboratory but also on a larger scale in the field. Because of its high energy efficiency and thus good CO2 footprint, electrochemical seawater desalination can play a major role in regions suffering from freshwater shortages.”
Instead of using reverse osmosis, which requires high-pressure pumps to force water through semi-permeable membranes, the Siemens process relies on electrochemical desalination. The process combines electrodialysis (ED) and continuous electrodeionization (CEDI), both applying an electric field to draw sodium and chloride ions across ion exchange membranes and out of the water. As the water itself does not have to pass through the membranes, the process can be run at low pressure, and hence low power consumption.
Why can’t we convert salt water into drinking water?
Article courtesy of Nicholas Gerbis | September 2, 2013 | howstuffworks.com | Shared as educational material only
It seems strange that water should be such a scarce resource when our planet is drenched in 326 million trillion gallons of the stuff. But it turns out that less than one-half of 1 percent of it is drinkable. Out of the rest, 98 percent is oceanic salt water and 1.5 percent remains locked up in icecaps and glaciers. The stark irony of Samuel Coleridge’s immortal line “Water, water, everywhere / Nor any drop to drink” is manifest each year in coastal disasters around the world, like Hurricane Katrina, the 2004 Indonesian tsunami and the 2010 Haiti earthquake, as people within sight of entire oceans are threatened with dehydration.
Between droughts, natural disasters and the large-scale redistribution of moisture threatened by climate change, the need for new sources of potable water grows with each passing day. Each year, the global population swells by another 85 million people, but worldwide demand for freshwater increases at twice the rate of population growth, doubling every 20 years or so [sources: OECD, UNDP]. Throughout the world, our most vital resource is under stress from pollution, dam construction, wetland and riparian ecosystem destruction, and depletion of groundwater aquifers, with poor and marginalized populations getting the worst of it [sources: Gleick, Gold, OECD, UNDP, UNESCO-WWAP].
So why can’t we convert seawater into drinking water? Actually, we can and we do. In fact, people have been making seawater drinkable at least as far back as the ancient Greeks. But when taken to the scale of cities, states and nations, purifying seawater has historically proven prohibitively expensive, especially when compared to tapping regional and local sources of freshwater. However, as advancing technology continues to drive costs down and freshwater continues to grow scarcer and more expensive, more cities are looking to seawater conversion as a way to meet this vital demand [source: Maloni].
Read on to find out how and where seawater is being converted into drinking water today, including how desalination is bolstering disaster relief in Haiti.
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