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60. Depletion of ions through freezing concentration for water desalination

K. RUDOLPH (1), P. Hahner (1), T. Kunz (1), F. J. Methner (1); (1) Technische Universität Berlin, Berlin, Germany


Of the total amount of water on earth, 97% occurs as salt water and just 3% as fresh water. Only 0.3% of fresh water is available as drinking water. Due to an increasing global industrial demand, water consumption is increasing steadily (70% of fresh water is used for food production). There are methods for seawater treatment, such as reverse osmosis and evaporation, however, these are very complex and expensive. Therefore, it is necessary to find alternative methods for seawater desalination. One possibility is the freezing concentration. If salt water is frozen, only the pure fresh water freezes. The salt is displaced, because it cannot be integrated in the ice crystal lattice. In order to yield water with high purity and drinking quality, it was important to avoid spontaneous crystallization during the freezing process, which occurs due to the supercooling of water. The disadvantage of spontaneous crystallization is that due to the rapidity of the freezing process the concentrated brine is incorporated in the lattice, and therefore, the ice purity decreases. Controlled crystallization was achieved through the application of seed ice. The purity of ice and, therefore, the depletion of salt could be increased up to 40–60% by controlled crystallization compared to spontaneous crystallization. It was observed that all ions were depleted to the same extent over the freeze concentration. This fact is of great interest for the beverage industry, especially for the brewing sector. It is possible to treat water and wastewater specifically by freeze concentration. For example, to increase the colloidal stability of the beer, the content of iron in the brewing water can be decreased in advance.

Kerstin Rudolph obtained her graduate engineering degree in food technology, with thematic priority on extraction of food ingredients and food microbiology, from Technische Universität Berlin in 2013. In her diploma thesis in the Department of Food Technology and Food Chemistry, Chair of Brewing Science, she investigated, in cooperation with Herbstreith & Fox KG, the effectiveness of pectin in the colloidal stabilization and fining of beer. Since 2013 she has been employed at the Chair of Brewing Science as a scientific assistant. In August 2014 she started working on the cooperative project Seawater Desalination through Freezing Concentration.

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