Desalination plants turn seawater into drinking water, providing a critical resource for many dry regions around the world.
But this process comes with a big downside: for every liter of fresh water produced, it creates about 1.5 liters of salty waste, known as brine. Globally, desalination plants produce over 37 billion gallons of brine waste every day.
This brine is often stored in large evaporation ponds, injected underground, or dumped into the ocean—methods that take up space and can damage the environment.
Now, engineers at the University of Michigan have developed a new membrane technology that could make desalination more eco-friendly by reducing or even eliminating brine waste.
Their research, published in Nature Chemical Engineering, introduces a more efficient way to concentrate and remove salt using less energy.
Instead of relying on evaporation or standard reverse osmosis, which struggles with high salt levels, the team uses a process called electrodialysis.
Electrodialysis separates salt from water using electricity.
As salt in water exists in the form of charged particles (ions), electrodialysis uses a series of membranes with alternating electrical charges to guide these ions into separate channels. One stream becomes purified water, while the other becomes concentrated brine.
The challenge with current electrodialysis membranes is that they tend to leak salt at high concentrations, or they work too slowly to be practical.
The University of Michigan team solved this by packing their new membranes with a much higher number of charged molecules. This not only blocks leaks more effectively but also increases the membrane’s ability to carry salt—making the process faster and more energy-efficient.
To prevent the membranes from swelling and becoming diluted—something that happens when they absorb too much water—the team used special carbon connectors to hold the charged molecules tightly together. These connectors allow the membranes to stay dense and maintain strong performance.
An exciting feature of the new membranes is that they can be tailored for different uses. Depending on the situation, engineers can tweak the membranes to balance how much salt they let through and how much energy they need. This flexibility could make the technology useful in many types of desalination systems.
Besides producing fresh water, this approach could also help recover valuable materials like lithium, magnesium, and potassium from seawater—resources needed for batteries, fertilizers, and more.
If widely adopted, this new membrane technology could make desalination cleaner, more efficient, and more sustainable, offering real hope in the fight against global water shortages.
