A new approach to water desalinization suggests solvent extraction technology could successfully treat high salinity water for a fraction of the energy needed for other methods. If successfully commercialized, the technique could be a “disruptive technology,” according to the research engineer managing the project.
Temperature swing solvent extraction “is a radically different desalinization technology” that does not involve membranes nor evaporative phase change, said Ngai Yin Yip, assistant professor of earth and environmental engineering at Columbia University and leader of the research project. As published online in Environmental Science & Technology Letters, the study asserts TSSE technology can desalinate high salinity brines “up to seven times the concentration of seawater.”
The research demonstrates TSSE, described as “low-temperature heat and a low-polarity solvent with a temperature-dependent water solubility,” selectively extracts water over salt from saline feeds. It tested high-salinity brines simulated by NaCl solutions with three amine solvents and up to 234,000 TDS. Results achieved 98.4 percent salt removal.
“This study underscores the unique capabilities of TSSE for desalinization of hypersaline brines,” the research paper concluded.
For years, large scale desalinization projects relied on reverse osmosis and thermal distillation, both very energy intensive. According to the International Desalination Association, more than 20,000 desalination plants are operated in 150 countries and provide water to 300 million people.
The high capital investment and operating costs and the environmental concerns raised by their energy consumption has limited the number of desalinization plants around the world. Traditional sources of freshwater remain less expensive than desalinization in most places.
Temperature swing solvent extraction “can displace costly distillation of high-salinity brines and tackle higher salinities that RO cannot handle,” researcher Yin Yip said. He added that because it requires far less heat than distillation, TSSE could be cheaper to scale if it used industrial waste heat, geothermal or oilfield associated gas.
Providing inexpensive and sustainable freshwater while reducing the prevalence of hypersaline streams would “eliminate pollutions problems and create cleaner, more useable water for our planet,” Yin Yip said.