A new desalination process called Reverse Osmosis-Pressure Retarded Osmosis (RO-PRO) is being developed in California.
Researchers from Humboldt State University and the University of Southern California believe that their system could lower the cost of desalination and reduce its impact on the environment.
It incorporates both reverse osmosis — a commonly used process in desalination plants — and pressure-retarded osmosis to help overcome the drawbacks associated with reverse osmosis, namely that it is expensive, energy-intensive and can negatively impact the environment when the leftover salty brine is reintroduced into the ocean.
With PRO, fresh water is combined with sea water in a pressurized chamber, creating water pressure and generating power. As Humboldt State University explains, when combined with RO that energy can be used to power the entire system. The researchers say that the process uses 30 percent less energy than traditional desalination methods.
Moreover, the highly-concentrated saltwater is eventually diluted back to seawater, reducing environmental harm.
"If used on a large scale, it could have a positive environmental effect and result in significant cost and energy savings," said Andrea Achilli, an Environmental Resources Engineering professor at Humboldt State University.
The research team has been awarded a $600,000 grant from the California Department of Water Resources to develop a portable, prototype RO-PRO system in Samoa, Calif. It will be installed at the Samoa Pump Mill, where water from the Mad River meets the Pacific Ocean.
After a year-long trial testing the efficiency of the system, the researchers hope the technology will be built into desalination facilities in California and elsewhere.