Native Bacteria Used To Clean-Up Uranium Mines

Oct 10, 2014

Senior Scientist Jim Clay on a foggy day at Smith-Highland Uranium Mine near Douglas, WY.
Credit Melodie Edwards

There are currently over 4,000 abandoned uranium mines in remote corners of the US. Out of sight, but for people living nearby, not out of mind. Uranium produces radon, which is known to cause lung cancer. In 2012, uranium was found in the tap water on the Wind River Indian Reservation. Many say the time has come to clean up the mess. But that could cost billions. The Obama Administration is tackling the job by pushing for new fees on mining companies, but the industry says they’re too punishing. Now, new research could make uranium clean-up significantly cheaper.

Fog drapes heavy over the rolling prairie at the Cameco uranium mine in eastern Wyoming. It’s not what you imagine a mine to be. A few steel huts and little metal boxes visible through the clouds--that’s it. No open pit in sight. That’s because it’s an in situ mine--a network of pipes underground. And those little boxes?

“Those are simply covers from well heads,” says Cameco Spokesman Ken Vaughn. “And what we’ve done here is figure out where the uranium is underground. It’s in an aquifer. An aquifer that’s not drinking water quality obviously. For one thing, Mother Nature put a lot of uranium down there with it.”

This mine at Smith-Highland Ranch near Douglas is no longer in production. It’s ready for clean-up. But the problem is that all the usual methods use massive amounts of water. Hundreds of thousands of gallons blasted through the mine’s pipes. And afterward, it has to be stored as waste water forever. And it isn’t cheap. A single mine like this one could cost as much as $15 million to restore. University of Wyoming Geology Professor Kevin Chamberlain is working on the project. And he says none of the usual options provide a permanent fix.

“They come three, four months later and it’s rebounded because the uranium was not actually fixed chemically,” he says. 

"I believe one of the big issues of the 21st Century will be water. Not just here but in the entire world. The techniques that are being worked upon here are hopefully transferable to other mines."

So scientists from the University of Wyoming, Los Alamos National Laboratory and several others have been searching for better, cheaper methods. Chamberlain says they’ve struck upon something that isn’t actually new. It’s already been used to clean up environmental disasters like oil spills and super fund sites….It’s bacteria.

“They’re incredible little critters,” Chamberlain says. “We can’t live without them. Our body is full of them. But they also interact with the environment in ways that clean up our messes.”

But what is new is using the native bacteria that naturally thrive near uranium deposits. In fact, some scientists think these local bacteria might have been part of the process of depositing the uranium in the ground in the first place.

“And the beauty of the approach we’re taking is that the bacteria do this naturally as part of their lifecycle,” Chamberlain says.

The way it works is that the bacteria take uranium in its wet form-- where it could contaminate groundwater-- and convert it to a nice, safe crystalline form.  Normally, though, this natural process is geologically slow. Literally. So the scientists started trying to find the perfect potion to get these native bacteria jazzed up in hopes of speeding the process along. A few years back, Cameco thought they had the recipe.

“They talked about how the perfect mix was Coca-Cola, molasses and alcohol.  They were feeding the bacteria a cocktail,” says Chamberlain.

But the bacteria at Smith-Highland Ranch apparently were teetotalers. No sign of reduced uranium. The scientists were back to square one.

Enter Microbiologist John Willford. He’s the guy babying these bacteria in a freezer lab. Today’s he’s refilling lab tubes full of the magic native bacteria with Cameco’s mine water.

“They really just needed somebody to grow bacteria well,” Willford says, laughing. “That’s something I definitely feel I can do.”

Willford was the one who discovered the bacteria’s ambrosia. It wasn’t sugar or booze. They prefer milk. A protein called triptone, to be exact. But Willford says that’s just the picky eating habits of these bacteria at this mine. 

“Your microbial populations are going to be different. Your geochemistry is different. And so you wouldn’t necessarily expect that the same food is going to feed the system and have it work in the same way.”

So triptone works here. But, for instance, it might not work to restore the nuclear weapons mine in Rifle, Colorado. The bacteria there might just prefer that Coca-Cola cocktail.

The time has come to try the project in the field. Cameco’s Senior Scientist Jim Clay shows me into the header house where the new pump is waiting to circulate the triptone through the underground pipes. 

“There’s a mixture there we’ll add a powder to the water and it’ll mix it up and turn it into a solution.”

Clay wears thick, round glasses and a white lab suit…and looks just like a mad scientist cartoon character. Clay says he’s confident the project will work—and not just for his company.

“I believe one of the big issues of the 21st Century will be water,” Clay says. “Not just here but in the entire world. The techniques that are being worked upon here are hopefully transferable to other mines.”

And with more nuclear power plants going up than ever before, especially in China and India, Clay says it’s critical to make it cheaper and simpler to clean up uranium mines around the world.