Demonstration of the Natural Freeze-Thaw Process for the Desalination of Water from the Devils Lake Chain to Provide Water for the City of Devils Lake

摘要

Natural freeze-thaw (FT) desalination of saline surface water is demonstrated in North Dakota for the purpose of providing a new water supply for the City of Devils Lake. The project took saline feed water directly from Devils Lake and desalinated it using the natural FT process. Samples of feed, treated water, and concentrated brine were collected and analyzed during operations to allow sufficient data to be collected to determine the performance and cost of a full-scale FT plant and to validate the demonstration of the process. Site selection, simulation testing, and design and construction of the FT demonstration plant were performed during the summer and fall of 1998 followed by plant startup and shakedown in late December of that year. The FT plant was operated in the freezing mode for 2 and one half months (from January 1 to March 15, 1999) during which time 4.4 million gallons of Devils Lake water was applied to two freezing pads. Over the next 2 and one half months (through June 2, 1999) the ice was allowed to melt, resulting in the recovery of 3.68 million gallons (84 percent by volume) of treated water with a salinity of 450 ppm total dissolved solids.