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Researchers Work To Keep Desalinated Water Affordable

May 7, 2019

Water is a scarce resource in southern New Mexico. The Rio Grande often runs dry, forcing residents to pump fresh groundwater. But there’s another potential water source in the region: brackish groundwater. Researchers are studying how to transform this salty water into fresh, drinkable water - without breaking the bank or harming the environment.

 

On a dusty stretch of land in Alamogordo, there’s a whole facility dedicated to studying brackish groundwater. The space has a pretty lengthy name: the Brackish Groundwater National Desalination Research Facility. That’s quite a mouthful, so most people call it BGNDRF. It was built over a decade ago, to serve as a hub for researchers from all over the country.

On a recent facility tour, BGNDRF staff showed off the site. There’s room full of equipment that can transform brackish groundwater into fresh, clean water - the kind you could drink or sprinkle on crops - through a process known as desalination. There are two large evaporation ponds, and long rows of a special desert shrub that sucks salt out of the soil.

“Brackish groundwater desalination, that has been a mature technology for many years,” says Pei Xu, who teaches civil engineering at New Mexico State University. “So the technologies are there. But these technologies are challenged by a few technical and environmental issues.”

One of the biggest environmental issues is what to do with something called brine - the salty concentrate that gets left behind during the desalination process. This is a unique challenge for inland states, like New Mexico. Coastal cities have a vast supply of salty seawater. They convert that into drinking water, then inject the brine back into the ocean. That’s not an option here.

“We have limited options for the brine disposal,” says Xu. “So right now one option is through the deep well injection, inject it underground.”

Another is to discharge the brine into an evaporation pond, like the ones at BGNDRF. Once the water evaporates, the salt can be carted off somewhere else. But these and other proposed options all have potentially negative environmental impacts. So Xu and other researchers are looking at ways to minimize those impacts.

“The concentrate disposal is a key component for us to consider,” Xu says.

Another major challenge is simply the cost. Desalination is expensive. And that cost will likely fall on consumers, in the form of higher water bills.

“We’ve been blessed with cheap water for a long time,” says Phil King, with the civil engineering department at NMSU. “We are not going to run out of water. However, we are out of cheap water.”

That’s why BGNDRF was founded. The goal is for researchers to develop the most cost effective desalination technologies, so consumers aren’t hit quite as hard.

Alamogordo is currently building a desalination plant. Water experts hope breakthroughs at the nearby research facility can help keep the costs down and the environmental impacts minimal, and provide a model to other inland states.