Bacteria could be the key to a safer, greener way of processing rare-earth metals

The word “bacteria” doesn’t exactly evoke positive images, but scientists at Cornell University recently discovered a novel way to replicate and use a bacterium from Oneida Lake in New York state.

It’s called Shewanella oneidensis, and it has a special affinity for the rare-earth elements — such as so-called lanthanides, metals that are important for clean, renewable energy technology.

The bacteria can be used to process rare-earth metals through a method called biosorption, which is considered safer and less taxing on the environment than current means of extraction.

Marketplace’s Lily Jamali discussed the findings with Buz Barstow, a professor of biological and environmental engineering at Cornell and a lead researcher on the project.

The following is an edited transcript of their conversation.

Buz Barstow: So it enables us to make, we think, [an] extremely scalable, environmentally friendly process for separating individual lanthanides — exactly the thing you need for electric vehicles, wind turbines, superconductors. And it lets you do it not just, say, in China or other sort of less advanced economies. This is a process that we think is good enough, is environmentally friendly enough, to let us do this in the more advanced nations with more stringent environmental regulations. So it avoids us getting into this — my program manager, he called it eco-colonialism, where we externalize the CO₂ problem. We say, “We want to solve this environmental problem, so we’re going to create these other environmental problems over in this other country.” This technology and technologies like it let us avoid that dilemma.

Lily Jamali: And why is that a better alternative to how we process rare-earth elements today?

Barstow: That’s a great question. It doesn’t involve any harsh chemicals. So today, we rely on a solvent extraction process to purify them. So organic solvents, they have a tendency to be carcinogenic. They’re terrible for the environment in other ways as well. We also use what’s called an organophosphorus-based extractant as well. That’s a molecule, again, carcinogenic, that has a small preference for one or a small number of rare-earths. Because that doesn’t have an enormous preference for any one rare-earth, you have to do this sort of successive enrichment process. So you need gallons and gallons and gallons of it. And you need sort of incredibly long separation processes as well. So there’s loads of potential for leakage as well.

Jamali: So in addition to being more environmentally sustainable, is this approach that researchers are working on, is it also more scalable?

Barstow: I would like to think so. We’re not the only people who are working on biological approaches to separating rare-earth elements. I can think of at least two colleagues — Joey Cotruvo at Penn State, Cecilia Martinez-Gomez at [the University of California] Berkeley — who are also coming up with bio-approaches. And they’re taking sort of, you know, very different approaches to the one we are. I’d like to think Shewanella and biosorption, in general, it has a lower specificity than their approaches. But it’s easier to get the rare-earths off the surface of the absorbing agent. So it might make for a faster, more scalable process. Also, biosorption doesn’t require that you purify anything, either. All it requires is biomass. We just have to grow cells, that’s really easy, doesn’t require any purification.

Jamali: When do you think we could see this in real life, a test run, a pilot?

Barstow: You know, I think it’s like, where there’s a will, there’s a way. I’d like to think that there’s enough momentum behind these technologies, there’s enough interest to fund them. I’ll use this opportunity to give a plug for my grad student, Sean Medin. Sean was the first author on this paper. and he and Alexa Schmitz — Alexa was my first postdoc [researcher] in my lab — founded a company called Reegen to commercialize this technology and also technology for engineering microbes to dissolve rocks to get rare-earths out of them as well. What they’ve done is they have opened up the opportunity for sort of commercial investment in this.

More on this

According to the U.S. Geological Survey, China is the global leader in rare-earth metals, producing 70% of the world’s supply.

But a report from the Yale School of the Environment finds that has come at a cost to the country in the form of serious water and soil pollution issues.

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