2025 AIChE Annual Meeting
Optimization of Cost-Effective Cryodesalination As a Water Purification Technique
About 71% of Earth consists of water, which equates to approximately 326 million cubic miles of water, but only 2.5% of that is potable. Of that 2.5%, only 0.3% is accessible to humans. Although water is a fundamental source of life, disparities in the world result in 1 out of 10 people lacking access to clean drinking water. As the Earth’s population continues to increase, it becomes more crucial to find alternative desalination methods to provide potable water to humans across the world. Cyrodesalination is a desalination technique that removes salt from seawater via cooling. By utilizing saltwater’s thermodynamic properties and carefully controlling the system temperature, saltwater can be cooled enough to freeze only the freshwater, leaving the salt behind. UC San Diego’s current prototype utilizes affordable and abundant materials to execute the desalination. The design features a pre-filter that reduces contaminants in the starting solution, a cooling bath using 99% acetone and dry ice, copper cups to hold the solution, and stir bars for mixing. In the past 2 years, the heat transfer efficiency has increased by reducing the time to reach freezing in half, using stir rods to minimize temperature gradients within the solution. Inclusively, 99% acetone as a coolant material (insulated using a cooler) prevents heat loss/gain from the surroundings and the cooling bath. The current prototype has had a successful reduction of salt concentration from 23 ppt to 16 ppt. To further reduce salt concentration and optimize the efficiency of the process, our next steps are to update various process parameters, which will be scheduled to test. Future work will target filtration materials, such as fine sand and granulated activated charcoal, that exhibit promising filtration properties to remove contaminants present in seawater. By implementing such materials in the pre-filtering step, salt concentration readings will yield more accurate results. Lastly, to increase the heat transfer area, copper fins will be attached to the cups holding the solution to increase the surface area for heat transfer between the cooling bath and brine.