A Finnish University recently discovered the benefits of crystallization, or freezing water in order to purify it. Essentially, these scientists found that the upper layer of ice from a lake in Finland was nearly ten times cleaner than the water beneath. In addition, ice that had formed more slowly was noticeably cleaner than rapidly formed ice. This event called crystallization can only occur with the presence of a solvent and solute, such as water and salt. A professor from Lappeenranta University of Technology (LUT) made the statement below regarding the study.
“Lake water contained about ten times more impurities than the ice…the slower the layer of ice grows, the cleaner the ice is.” – Professor Marjatta Louhi-Kultanen
Researchers from LUT admitted that this process does not completely purify sea water, however it is a great method of removing impurities. Evidently, clean ice is a naturally forming product in the Arctic Circle. Crystallization is also energy efficient because it uses seven times less energy than evaporation to create cleaner water. Once the ice is collected it can go through a secondary purification stage like membrane filtration and then will be ready for use. Researchers at LUT suggest this method be used in places that require large volumes of water, but not completely pure water, such as mining practices or other industrial efforts. Overall, crystallization is a unique method to keep in mind when you think of all the salt water covering Earth. Read more on freezing water purification here.