Science can solve mining risks, but only if we demand it

Bioreactors in an old Erie mine pit remove sulfates. (PHOTO: Clearwater Layline, LLC)

Aaron J. Brown

Aaron J. Brown is an Iron Range blogger, author, radio producer and columnist for the Hibbing Daily Tribune.

As a nerd who grew up on an Iron Range junkyard, I appreciate anything that combines groundbreaking science with homemade contraptions. That’s why I’m fascinated by a daisy chain of unobtrusive barrels floating in an old Erie Mining pit outside Babbitt, Minnesota. They may save our world.

Jeff Hanson put them there. Hanson is an Iron Range native who now lives part time at his family land near Birch Lake. His training in mechanical engineering led him to the forefront of scientific efforts to understand and mitigate the environmental risks posed by mining, farming and treating wastewater.

Hanson spent 26 years working on environmental processes for mines in Brazil. Now he’s part of a company called Clearwater Layline, LLC. They’re on the precipice of technology that could protect Northern Minnesota waters forever.

So what’s in the barrels? Long strands of ultra thin fibers. These threads add enormous surface area inside the barrel. Bacteria collected from deep below nearby stream beds thrive on them. In fact, Hanson would prefer we call them “bioreactors.

Those bacteria eat sulfates.

You’ve heard that word before. The debate over sulfates, sulfides and mining is at the heart of a raging political and cultural battle in Minnesota. The very mention of the word invokes an almost hopeless impasse. Until you get to know about these bioreactors.

“So what we are doing is mimicking nature,” said Hanson.

Scientists culture sulfate-reducing bacteria in bioreactors. In an oxygen-free environment these bacteria chemically convert sulfide to a benign solid, iron sulfide, instead of the poisonous form at the heart of the debate.

“Nature also does this if there is sufficient iron available,” said Hanson. “We just make sure of that. We’re doing it in a mine pit lake. We take it out before it goes downstream. This protects wild rice and all plants.”

These bacteria feast on sulfates year-round since the bioreactors reach below the winter ice.

Much of the sulfate standard debate centers on whether or not proposed nonferrous mines like PolyMet or Twin Metals should receive environmental permits. But that belies a more immediate reality. Sulfate-laden mine pits dot the entire Iron Range right now. That’s why mining companies remain nervous, even hostile, about the state sulfate standard.

Bioreactors process sulfates at a retired iron mining pit near Babbitt, Minnesota (PHOTO: Clearwater Layline, LLC)

No matter what happens on controversial new projects, the existing problem requires a solution.

PolyMet currently proposes to use reverse osmosis technology at its mine. This technology works in trials, but it’s very expensive to build and run. Taconite mines and city wastewater plants flatly refuse to consider it due to cost.

Further, reverse osmosis is essentially a machine that would need to be maintained in perpetuity. Think of a pickup truck you try to keep running for 500 years. Not a simple or affordable task. It’s easy to imagine some future owner running out on the whole deal.

Hanson says his company’s systems cost less than 10 percent the price of a reverse osmosis system. Further, they require only minimal maintenance afterward. Essentially, the bacteria do the work. As long as they’re fed and kept in an oxygen free environment they’ll keep going. One reactor can process 500 gallons of water from 1,000 ml of sulfate to zero in a single pass. If you need to process more water than that, just add more reactors.

“Our campaign is to get the mines to authorize us to put something in,” said Hanson. “We would love public support, but private backing here would be appropriate. We want the public to understand that there are solutions, maybe other than us, too — we don’t have to be just shouting at each other all the time.”

Hanson said early talks with Ojibwa tribes in the region have been promising. By focusing on technology that cleans the water, rather than the economic argument about the mines, common ground may be reached.

This brings us to another important aspect of this discussion: public policy and regulations.

Hanson and I agree on one important point. Minnesota should have a defined sulfate standard as part of its clean water regulations.

“I think a lot of people have the idea that we can’t regulate the mines without killing the mines,” said Hanson. “That’s not true.”

Hanson said the standard should be closer to the current unenforced standard (10 mg/L) than the mines would like. You might have seen mining representatives tout a standard well about 1,000 m/L. Hanson, who supports mining, isn’t buying that argument.

“Whether [the standard should be] 5, 10, 50, 100, I don’t know,” said Hanson. “All I know is that it’s not 1,000. I haven’t seen any scientific data that supports anything much higher than 10.”

Sulfates aren’t poison. You can drink them and swim in them. But they pose a risk to become harmful sulfides once released from a pit, especially years later. Sulfides don’t just kill wild rice, they turn rivers into canals of poison, usually long after the mine closes. We can prevent this by treating the sulfates in the pit. That’s why we have the regulation in the first place.

That doesn’t mean that we have to abandon mining or its important role in supplying our nation with raw materials (and yes, employing a number of us here in Northern Minnesota). It means that we have to use human knowledge and a small fraction of corporate profits to mitigate the risks.

I’d like to see what these bioreactors can do in the pit lakes across the Iron Range. Wouldn’t you? We could solve an obvious problem and cool a hot debate. Most important, we could help keep Iron Range water clean forever without jeopardizing our economy in the short run.

But it’ll never happen if we don’t accept low-sulfate water as a shared goal.

Aaron J. Brown is an author and college instructor from northern Minnesota’s Iron Range. He writes the blog and hosts the Great Northern Radio Show on Northern Community Radio. This piece first appeared in the Sunday, July 15, 2018 edition of the Hibbing Daily Tribune.


  1. Aaron:
    Great post – its encouraging to read about new technological approaches. I have a background in mine remediation and am intimately familiar with acid mine drainage in the western US. Because of that, I have been deeply suspicious of proposed non-ferrous mining in northern MN. This technology would help and you are dead right about establishing a sulfate standard.

    What still bothers me is the dismal track record of precious metal mining companies in following through on their promises to protect the environment. It is still far easier for them to file for bankruptcy and walk away, which is still the business model they employ. I am not confident that negotiated financial assurances can really work.

    Have you looked into this aspect? Your blog would be a good place to explore this problem.

  2. Joe Musich says

    Wow ! I remember growing up in Hibbing with a mining father. And then him losing his job when Oliver pulled out. And then becoming excited for his possible return home on a permanent basis from leading a nomadic existence to support the family upon hearing about the miracles of the taconite process. Remember Hemitite vs taconite in science discussions as a child ? Well taconite got up and running and some people had work again close to home. But the waste creation of mining continued. Science offers mitigation but solutions come slowly and through investment tinkering and patience. It just hope if this can work on a macro scale it is up and running tomorrow. The forces pushing for the sulfide mining process have all the money in the world to fight their battle. Just look how long the effort to block the current standard for sulfates went unused.

  3. Bill Hansen says

    Clearwater Layline and other mitigation’s do offer hope for cleaning up the dozens of existing facilities that have been allowed to violate sulfate standards for decades. Hopefully, it will scale and allow for an effective cleanup that is long over due, creating good jobs and a new 21st century Minnesota industry in the process. Kudos to Hanson and his colleagues for their important work.

    In the context of new copper/nickel mines, better pollution control does not change the fact that it is simply bad economic development. Both economic studies and real-world experience show that copper/nickel mining destroys more economic activity than it provides, is subject to crippling cycles of boom-and-bust and leaves regional communities in persistent decline when the mining is over. (Not to mention that Glencore and Antofagasta are among the most corrupt, rapacious, and reviled companies in the world.)

    Companies like Clearwater Layline and Cirrus Designs, just to name couple, offer a better model for a real economic development strategy. A recommitment to excellent public education, support for entrepreneurs, single payer health insurance, universal daycare/pre-school and strengthened unions would be a good start to improving life for all of us in northern Minnesota.

  4. Gray Camp says

    Nice! Hope this technology can be proven on a bigger scale and implemented and that no one starts a bacteria rights campaign.

  5. NRRI is involved in the bioreactor research, and it refuses to disclose the mercury numbers they are seeing. Individuals involved have had to sign non-disclosure agreements. The sulfate standard is not just about wild rice, although the mining industry and the Minnesota Chamber of Commerce has done their best to make sure it stays that way. The sulfate standard is also, and most importantly, about methyl mercury and the health of generations of northeastern Minnesota’s children.

Speak Your Mind


This site uses Akismet to reduce spam. Learn how your comment data is processed.