Following a corn harvest, the husks, stalks and cobs left in the field form what’s called “stover.”
But that stover is far from garbage. At the Idaho National Laboratory, Dr. David Reed, Dr. Yoshiko Fujita, and Dr. Vicki Thompson are part of a team working with scientists at Purdue University and the U.S. Department of Energy to address a fast-growing crisis—e-waste that is piling up in poisonous amounts in the U.S. and globally. They published their research in Sustainable Chemistry and Engineering.
As corn stover blankets post-harvest fields, it provides nutrients to the soil beneath it. But some of that stover can be used for other purposes too, including making ethanol. Reed, Fujita, and Thompson said their findings show that Gluconobacter bacteria can extract metals from e-waste so they can be recycled by converting stover into sugars that feed and energize the metal-fetching bacteria.
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As the “gluco” part of their name suggests, Gluconobacter bacteria have a sweet tooth. They like sugar, similar to how people like cakes and donuts. The scientists were able to convert corn stover into the sugars those bacteria crave. Once loaded up with their own version of donuts, the bacteria are fueled to do the work of removing metals from e-waste.
The bacteria then dissolves and extracts metals in a process called “bioleaching.”
“The advantage of these bacteria is that they are so tiny they can cover the metal’s surface, and make their acid right where the metals are,” Thompson told The Daily Beast. “So they can get down in where other processes cannot, and can dissolve the metals more easily, [making] the metal change from solid to liquid. The acid the bacteria generate can essentially bind up the metals very tightly, so that acts to pull the metals out into a solution. Metals can then be extracted from the solution for recycling.”
Scientists have tried other similar avenues for mitigating e-waste, but they’ve proven to be prohibitively expensive and (ironically) environmentally unsafe. “From both an environmental and economic perspective, we needed to find a more efficient process,” Thompson said.
That’s when the team stumbled upon Gluconobacter’s acid-producing microbes.
“This process is a greener technology than a lot of other chemical processes, and probably all chemical processes,” Reed said.
Economic advantages to Iowa—the world’s largest corn producer—and other regional states could be considerable, as farmers would be paid for the stover they sell to bioleaching facilities. The team is researching plans for large-scale commercial facilities, where e-waste could be brought in by consumers or agencies, then recycled using the stover-fueled process. “In the lab the process is very small, but we’ve been able to scale it up,” Reed said. “We’ve been able to show that scale-up fairly resembles the smaller-scale studies we’ve carried out.”
No ivory tower is blocking out the realities of construction. “Any time you scale up, there are challenges,” Thompson noted. “We want to get to the point where we can demonstrate a pilot plant. Once we’ve demonstrated that, we can go full scale.”
“We’re looking at making the process cheaper than we already have,” added Reed.
It helps that sleek, powerful new technologies debut often. Consumers are enticed to update their devices, tempted to just throw old ones in a garbage can. Toxic e-waste pollutes air and water that’s hazardous to humans, especially children. Mountains of e-waste are creating a crisis globally, in landfills where it’s tossed. Some developed countries ship e-waste to undeveloped nations where trash regulations are few, creating literal pools of hazard.
According to the World Health Organization, more than 40 million tons of e-waste are produced each year and that number increases every day. Only about 25 percent of total e-waste worldwide is safely recycled. There is lead or lithium in wiring boards and batteries, mercury in printer ink and toners, and cadmium in semiconductor chips and phones. None of this is a good thing when it nestles into human lungs.
According to the National Institutes of Health, components can be cancer-causing if not recycled safely. A computer can contain beryllium, in addition to cadmium, mercury, or lead. There is evidence of beryllium and cadmium in cancer. Over time, cadmium can accumulate to toxic levels in the kidneys. Lead can be toxic to the nervous system, resulting in motor neuropathy, anemia, and genitourinary diseases.
Mercury is a neurotoxin that can damage the nervous system and fetuses. Mercury can drift into rivers, lakes and oceans, where it does not degrade, but instead continues to poison water long after it first sinks in.
Straining collection efforts is the reality that there are not enough e-waste facilities to manage the tidal wave of gadgets that are passing into and out of the modern world. Moreover, there is significant lack of public awareness that e-waste should be recycled and not just trashed.
“Collecting the e-waste is really a major need, a gap that needs to be filled,” Reed said.
“Our research is just one step within a very large chain of things that have to happen,” Fujita explained. “In order for recycling to occur, one of the big challenges is gathering the e-waste. We do not have a good collection system. Building that up is part of a much larger system. It’s a large and expensive challenge, as we don’t have a collection system.”
She said that even if bioleaching turns out to be a great way to recycle, unless consumers can be persuaded to contribute, it won’t work. “People want to get rid of it,” Reed said. “So unfortunately, it goes in the trash.”
