INTRODUCTION OF SEAWATER DESALINATION METHODS
Desalination is the use of seawater desalination to produce fresh water. It is an open-source incremental technology to realize the utilization of water resources. It can increase the total amount of fresh water without being affected by time, space and climate. The water quality is good and the price is gradually becoming reasonable.
The process of obtaining fresh water from sea water is called desalination. If fresh water could be obtained from sea water, it would be a huge natural resource. Although desalination is not economically justified in most cases, there are now hundreds of SWRO Desalination System in operation around the world.
The first desalination plant was built in the United States in 1954 and is still operating in Freep-ort, Texas. The desalination plant in Key West, Florida, is one of the largest in the world and supplies the city with water.
The Seawater Desalination methods currently used include seawater freezing method, electrodialysis method, distillation method and reverse osmosis method. At present, the reverse osmosis method using reverse osmosis membrane has quickly occupied the market with its advantages of simple equipment, easy maintenance and equipment modularization, and gradually replaced it. Distillation is the most widely used method.
There are two methods of desalination used.
One is called reverse osmosis. Typically, a concentrated solution can absorb water from an external dilute solution, just as plant roots can absorb water from soil. Conversely, in order to penetrate the water in the concentrated solution, high pressure must be applied. This method of infiltrating fresh water from seawater under the action of external high pressure is reverse osmosis. The applied high pressure is proportional to the salt content of the seawater. Generally, reverse osmosis seawater desalination should be added to 80 atmospheres. Therefore, the size of the reverse osmosis container should not be too large, otherwise, the strength of the reverse osmosis membrane and the container will be a problem. Therefore, the Seawater Desalination Reverse Osmosis method is only suitable for small-scale desalination of islands and brackish water desalination in inland areas, because the salt content of brackish water is much lower than that of seawater.
The other is called distillation. The principle of this method is very similar to boiling water at home. Boil seawater in a kettle, and there will be condensed distilled water on the lid of the kettle, which is desalinated water. However, when desalination, in order to save energy, the steam from the first pot is used to burn the steam of the second pot and then the third pot, and so on, and then all the condensed water is collected, which is the production of desalination water.