All around the world, countries are investing in plants to turn saltwater into fresh water to make sure their people have enough to drink in an increasingly drought-prone and populated world.
But prevailing methods of desalination are both expensive to operate and end up creating more wastewater than drinking water, an environmental hazard that potentially undermines their purpose.
Now a team of researchers at Columbia University claim to have created a “radical” alternative form of desalination called “temperature swing solvent extraction” (TSSE) that is more effective, cheaper, and can even clean the toxic sludge generated by other methods, according to a study published in the science journal Environmental Science & Technology Letters.
TSSE works by adding briny water to a unique solvent. The briny water sinks to the bottom because of its higher density, and then the mixture is placed in a low-heat temperature bath, where the water separates into the solvent. The solvent, now containing the water, is extracted and put into another temperature bath, which allows the water to be cleanly extracted.
The researchers say that the method removes up to 98.4% of salt, which is same efficacy rate of reverse osmosis, the preferred industrial method. TSSE can treat brine that’s seven times as concentrated as seawater, making it twice as powerful as reverse osmosis, according to the researchers.
The team thinks that the method can be used to turn brine into water that’s suitable for irrigating crops, industrial cooling purposes, and even human consumption.
“We think TSSE will be transformational for the water industry,” Ngai Yin Yip, the report’s lead author, said in a press release. “It can displace the prevailing practice of costly distillation for desalination of high-salinity brines and tackle higher salinities that RO cannot handle.
“This will radically improve the sustainability in the treatment of produced water, inland desalination concentrate, landfill leachate, and other hypersaline streams of emerging importance,” he added. “We can eliminate the pollution problems from these brines and create cleaner, more useable water for our planet.”
Currently, the desalination industry creates trillions of tons of toxic sludge each year that often gets disposed of in ways that pollute surface and groundwater sources.
Additionally, reverse osmosis plants require enormous amounts of energy, which, when powered by fossil fuels, cause greenhouse gas emissions.
TSSE doesn’t produce the same type or amount of wastewater and doesn't require a lot of energy. In fact, the method can be powered in sustainable ways, including through heat created by waste facilities and solar energy.
"A lot of industries generate low grade heat, and that means our technology can take this heat and use it to achieve our desalination process," Yip told Global Citizen. "So you’re looking at a very sustainable, cost-effective desalination process."
Yip said that TSSE isn't meant to replace current desalination efforts. Instead, it can act as a supplement that helps to mitigate the industry's environmental risks.
"This technology is not meant to compete against reverse osmosis," he said. "We’re trying to tackle brine that’s much saltier than reverse osmosis is able to handle."
"Our technology has the potential to enhance the ability to manage challenging waste streams," he said, pointing to the brackish wastewater generated by the oil and gas industry and inland desalination plants.
Yip said that he's already received dozens of calls and email inquiries over the past few days about bringing the technology to market. He hopes to oversee a pilot program within the next few years, and noted that it won't be hard to scale the process.
"All the components can be scaled up," he said. "They are readily available on the market for other applications, so you can very readily adapt them to our system."
By 2050, more than half of the global population could face water shortages. Climate change, meanwhile, will create winners and losers when it comes to water availability, as it shuffles global precipitation patterns, inundating some countries with water, and subjecting others to drought.
Pollution is another major threat. In Latin America, Africa, and Asia, nearly all rivers have been harmed by industrial runoff, the UN reports, and 80% of global wastewater and sewage is dumped without treatment into bodies of water.
To make matters worse, forests, wetlands, and soil have been heavily degraded around the world, impairing the ability of the planet to purify water.
Against this backdrop, TSSE could help countries better manage a precarious future.