About 70% of the earth’s surface is covered with water. 97% of the water on the earth is salt water. Salt water is filled with salt and other minerals, and humans cannot drink it. Less than 1% of all the water on earth is fresh water that we can actually use. We use this small amount of water for drinking, transportation, heating and cooling, industrial, and many other purposes.
Development of cost-effective ways of producing fresh water
Most of the modern interest in desalination is focused on developing cost-effective ways of providing fresh water for human use. Along with recycled wastewater, desalination is one of the few rainfall-independent water sources. Due to the relatively high energy consumption involved, the costs of desalinating sea water are generally higher than the alternatives (fresh water in the form of surface water such as rivers and lakes, groundwater, water recycling and water conservation), but alternatives are not always available and rapid overdraw and depletion of reserves is a critical problem worldwide.
Israel produces 40% of its water from seawater desalination
In 2002 there were about 12,500 desalination plants around the world in 120 countries. The most important users of desalinated water are in the Middle East and North Africa. Among industrialized countries, the United States is one of the most important users of desalinated water, especially in California and parts of Florida. The cost of desalination has kept it from being used more often.
Desalination is also used on many seagoing ships and submarines. One of the largest percentages of desalinated water used in any country is in Israel, which produces 40% of its water for domestic use from seawater desalination.
What is reverse osmosis?
The Ashdod Seawater Desalination Plant is located in Ashdod, Israel, some 40 km along the coast from Tel Aviv. Construction took place between 2012 and 2015, and the final result was a 20,000 m² plant with a production capacity of 100 million m3 per year set up for the seawater reverse osmosis desalination process.
Reverse osmosis is a water purification technology that uses a semipermeable membrane. The various areas of the plant, such as intake chambers for the seawater, preparation basins, disinfection areas, the purification section and the outlet section have to be protected with a reliable, robust chemical- and abrasion-resistant lining.
Basins have to be highly chemical resistant
The waterproofing material has to withstand abrasion caused by sand from the seawater, and has to be chemically resistant against saltwater and every chemical used in the de-mineralization and re-mineralization process. To ensure the watertightness of the structure, crack bridging properties are also essential. After the appropriate professional surface preparation by high-pressure water jetting, all surfaces were leveled with Sikagard®-720 EpoCem, followed by an epoxy primer, SikaFloor®-156. Every inch of the surfaces, covering 20,000 m², spray Polyurea, Sikalastic®-841 ST.
69% of world`s fresh water takes the form of ice
But almost all our fresh water takes the form of ice (69% of it, to be exact). If you could melt all that ice, and the earth’s surface was perfectly smooth, sea levels would rise to an altitude of 2.7 km. So we would do well to take care of this ice. Finally, take all the water on earth and you would have a blue sphere less than a third the size of the moon. And whether it is saltwater or fresh, this needs to be sustainably taken care of.
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