Toxin-Eating Fungi

Tear A Part Auto Recycling leads the way locally in exploring the use of mushroom mycelium to reclaim heavy metals from polluted soil. We speak with their environmental specialist, Kirsten Brinkerhoff.

The Red Butte oil spill of 2010 dumped 30,000 gallons of crude oil down one of Salt Lake’s main waterways, contaminating not only water but also the soils it came into contact with. Cleanup likely added even more chemicals into the mix. It was a progression from clean water to chemical cocktail. But what if there were an alternative, a way to clean up spilled hydrocarbons that was less harmful than the problem? Some scientists and industry specialists believe that there is, and that solution begins with mushrooms.

At Tear-A-Part, an auto recycling business along Redwood Road on Salt Lake’s west side, petroleum, mercury, lead and other substances leak from the wrecked vehicles on the lot every day. But here, these chemicals aren’t just going down the drain and into the soil. Instead, they are getting gobbled up by oyster mushrooms.

Containing these toxins is just as important as recycling the cars, says TearAPart co-owner Chris Mantas, who bristles at the assumption that all junk yards are dirty. When Mantas and his family started Tear-A-Part in 2002, they designed their business with an eco-friendly mission. In 2006, confronted with writing a stormwater pollution prevention plan, they decided to hire an environmental specialist—Kirsten Brinkerhoff, a native of Altamont, Utah. Armed with a degree in environmental science from the University of Utah and unstoppable enthusiasm, Brinkerhoff set Tear-A-Part on a course that not only separates them from other auto yards, but places the business at the forefront of innovation in the industry of bioremediation.

In a small corner office at Tear-A-Part, a bustle of activity can be seen through a huge picture window. As Brinkerhoff takes a quick phone call, I watch the comings and goings on the other side of the glass. A man and his son examine car batteries displayed on a shelf while staff in bright red hoodies buzz back and forth helping the customers that stream through the doors. The room is noisy with chatter and the muffled sound of machinery from outside.

In the office, a computer screen displays an Excel document with color-coded columns reading aluminum, copper, mercury down the side, and across the top what looks like a list of chemical compounds. Creased open and face-down over the keyboard is a copy of Paul Stamets’ Mycelium Running: How Mushrooms Can Help Save the World.

mushrooms kristenBrinkerhoff finishes her call and turns back to me. “I want to show you something,” she says, ducking her head under the desk. She re-emerges holding a toaster oven-sized clear Tupperware box. Opening the lid, she shows me her latest experiment. Inside are shredded pieces of what she calls cellulose; to me it looks like oily, damp ribbons of cardboard. She digs back a handful to show me the white threads growing between two layers of cardboard near the bottom. To my untrained eyes it looks like mold, but it’s actually mycelium. It’s the beginnings of a mushroom.

“Unfortunately, it’s not growing too well,” she tells me, putting the box away. “The conditions aren’t right, but I thought I would try anyway.”

Before the mushrooms, Brinkerhoff’s main antagonist was the stormwater pollution project. The high water table under Tear-A-Part’s lot made contaminants difficult to catch before they entered the water, but there was no good way to eliminate the storm drains. Research led her to filter boxes that could sift the contaminants and toxic sediment out of the water as it washed through the drain. With help from her co-workers, she built a three-celled mesh cage, the bottom cell filled with charcoal and the middle cell filled with straw. The top cell captured the toxic sediments.

The filters worked—almost too well. She was left with hundreds of pounds of toxic sludge filled with antifreeze, gasoline, motor oil and heavy metals. How to dispose of that mess?

Then, her brother gave her the Mycelium Running, and she was off and running.

To understand the power of fungi, a family of organisms that have been on Earth for at least 1.3 billion years (much longer than plants), we must first understand mycelium. The mushrooms that we know and love are only the small fruiting part of an often vastly larger organism, the mycelium. Like the roots of a tree, this vegetative part of the fungus, only a single cell thick, grows through soil and other substrates. Mycelia produce enzymes and acids that break down cellulose and dismantle chains of hydrogen and carbon, beginning the decomposition process.

This process is at the core of mycoremediation, a specialized form of bioremediation that uses fungi. In simple terms, even backyard compost is a form of bioremediation, or the breaking down and metabolization of organic materials. Bioremediation refers to the use of microorganisms to break down and extract contaminated materials—cadmium, lead, salts—from a site for safe disposal elsewhere. Mycoremediation uses special fungi to perform the extraction process. Of an estimated 1.5 million species of fungi on the planet, fewer than 10 species are known to be capable of mycoremediation.

Mycoremediation experimentation began in the 1980s, writes Harbhajan Singh, author of Mycoremediation: Fungal Biore­me­di­ation, focusing on a group of wood-decaying fungi classified as “white rot.” The project ended in failure, says Singh, due to poor marketing. Incre­dibly, the one place where mycoremediation didn’t get shelved was in Utah.

Today, Midvale-based engineering consultant group EarthFax Engin­eer­ing still occasionally uses mycoremediation—their most recent project having concluded a year and a half ago in New Zealand. Company president Richard White, a civil and environmental engineer, remembers when mycoremediation was on everyone’s mind. “In the early ’90s, researchers at Utah State University were working on developing a new technique using white-rot technology. The professors had applied for funding through a program which funded university level research into ideas with commercial viability and that’s where we came across the idea.”

The technology showed potential and was eventually patented. Earth­Fax took part in early pilot scale lab tests. The white-rot demonstrated effective at controlling dioxins, pesticides and hydrocarbons, so the company moved on to larger applications.

On sites in North Carolina and New Zealand, EarthFax treated wood preservative chemicals that had spilled and leached into the ground. Both projects finished with good results, but the small success was not enough to keep white-rot mycoreme­diation on the top of the list for bio­remediation practices. In the end, money, time and complexity weighed in against the technology. “Excavation and burying the soil in a landfill, even with the liability associated with that, is cheapest, so that’s what companies do,” explains White.

In 2000, a mycoremediation renaissance began when mycologist Paul Stamets, an independent re­searcher of mushrooms in the old growth forests of the Northwest, teamed up with researchers from Battelle labs in Bellingham, Wash­ington, to see if oyster mushrooms could clean petroleum out of contaminated soil. In the experiment, four piles of dirt were saturated with diesel and petroleum. One was treated with enzymes, one with bacteria, one with nothing and the last with oyster mushroom mycelium.mushrooms box

Within eight weeks all of the piles remained messy masses of lifeless dirt—except for the mycelium pile, which was vigorously growing enormous oyster mushrooms. Soil tests revealed that the dirt, once containing 10,000 parts per million (ppm) of hydrocarbons, now contained fewer then 200 ppm. Left alone for another few weeks, the researchers and Stamets witnessed insects returning to the soil, birds feeding off the insects and eventually other plants taking root. “These mushrooms are a gateway species,” declared Stamets, “a vanguard species that opens the door for other biological communities.”

Inspired by this account in Mycel­i­um Running, Brinkerhoff approached the Mantas family and found them surprisingly receptive to her new pollution control plan. In 2009, Brinkerhoff conducted her first experiment using microfiltration. Growing the mycelium in a bed of straw, she experimented with pouring the contaminated water over the grown oyster mushrooms and straw mats. “Instead of the water filtering through, the straw repelled it and the water ran off the sides,” recalls Brinkerhoff.

Water-repellant straw was soon to be the least of Brinkerhoff’s worries. As it turns out, growing mushrooms is more difficult than it sounds. Har­bha­jan Singh explains that successful mycoremediation depends on “the nature of carbon materials, quality and quantity of nitrogen, presence of specific stimulators, temperature, hydrogen ion concentration, aeration, water availability and water potential.” On top of all that, mycelium has fluctuating seasonal growth patterns that affect the rate of decomposition.

Brinkerhoff requested the time and money to travel to Washington. She went to train with Paul Stamets.

Brinkerhoff hands me a white hard hat and fits one of her own over her head of long, wavy blonde hair. We step out into the back lot where we dodge a tractor. I have to walk close to Brinkerhoff to hear her as she starts our tour past rows of old cars lined up on the oily black cement, waiting to be stripped.

As we enter a large shed where most of the noise is coming from, a mechanic pokes his head up from under the hood of a vehicle and waves casually. “Hola, como estas?” asks Brinkerhoff brightly. She leads me downstairs where huge metal tanks are filling with the car’s left over fluids. “Most of the damaging liquids never make it to my filters,” she says, patting the tanks plastered in warning stickers.

Back outside, we take a look at the drains. There are four in the processing lot, she explains, four in the post-processing yard and three in the parking lot outside the gates.

Once the filters fill up with the toxic sediment, Brinkerhoff collects it and mixes it with shredded cardboard substrate. “A food source for the mycelium,” she explains. Since the mushroom spores are too delicate to start the process, Brinkerhoff buys mushroom spawn from Stamets. She then seeds unsterilized layers of cardboard with the mycelium and, in troughs made of strawbales that look like a makeshift raised garden bed, she layers the spawn-seeded cardboard lasagna-style with the toxic sediment. “The mycelium will grow through the cardboard and fuse laterally,” says Brinkerhoff. “As the mycelium grows stronger it pushes to the top. I put wet cardboard as the top layer to insulate it and keep the moisture levels high.”

Very similar to Stamets’ experiments, Brinkerhoff’s best soil samples from Tear-A-Part show starting hydrocarbon levels at 30,000 ppm, reducing to 1,860 ppm after 12 weeks.

According to the EPA, at 220 ppm that soil is acceptable as road base— safe enough to be paved over by a four-inch-thick layer of asphalt, similar to standard commercial results from bioremediation used in large industry. That’s not clean enough for Brinkerhoff.

Chemical oxidation, the currently preferred remediation method, injects oxidizing materials such as hydrogen peroxide, ozone and potassium permanganate into the ground at the site of contamination. The chemicals are capable of converting petroleum hydrocarbon into carbon dioxide and water. These soils remain underground, or if at the surface they are removed to a landfill or incinerated. Though the process can be simple and cost effective, a 2004 EPA document on chemical oxidation lists some of the disadvantages, including “significantly altering aquifer geochemistry, producing significant quantities of explosive off-gas and presenting significant health and safety concerns.”

Laurie Goldner, president of Salt Lake-based environmental consulting business SAGE Environmental, a group that often uses chemical oxidization in remediation projects, thinks mycoremediation is interesting but not competitive. Goldner admits that the fact that it is a natural process is appealing, but many of SAGE’s bioremediation projects involve leakage from buried storage tanks, requiring a method that is effective 10 or 12 feet underground. “With mycelium we’d have to excavate the soil, build a treatment area, build a watering system, buy the spawn and give it constant attention. It is a balancing act and there is a lot to consider.”

Brinkerhoff hopes mycoremediation will someday replace other forms of bioremediation, including at an industrial level. “Eventually, I want soil good enough to grow food on again,” says Brinkerhoff. “If I had my wish, some day we could use mycoremediation to turn Superfund sites into clean land.”

Back at Tear-A-Part she is already planning two new experiments: a multigenerational spawning, repeatedly growing oyster mushrooms on the same sample to extract more hydrocarbons, and a multispecies experiment, using multiple varieties of mushrooms in an attempt to absorb the compounds left by the oyster variety. By June, Brinkerhoff should even have her very own growing office, a huge greenhouse space in the car lot, devoted to mycoremediation.

Learn to grow gourmet mushrooms with Kirsten

The first farmer I ever worked for was new at the business and eager to try everything. He bought goats for milking, oxen for pulling his plow; he planted blueberry bushes and grew grapevines—he even tried mushrooms. I was never involved in the mushroom project, but I recall watching two other farm volunteers working hunched over a log with a drill and some cork-shaped plugs. It seemed a strange way to get mushrooms, but apparently it was one of the farmer’s saner schemes.

Homegrown, DIY mushroom kits like the one I witnessed being assembled, usually of the easy-to-grow oyster variety, are readily available and for those who want a little more direction with their pile of inoculated straw or log with pegs there is now a Growing Gourmet Mushrooms class taught by Kirsten Brinkerhoff and offered this month through the Wasatch Community Gardens.

Learn about mushroom cultivation from start to finish with Kirsten and, for an additional fee, take home a mushroom log from the class. Pre-registration is required.

Saturday, March 10, 1-3 p.m. $15, log is an additional $20. Grateful Tomato Garden, 800 S. 600 E. 801-359-2658. http://wasatchgardens.org

UPDATE: The class listed above is full, but Wasatch Community Gardens will be holding another one (and a mushroom foraging class) later in the season. Keep in touch with WCG for details.

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Katherine Pioli

Katherine Pioli

Katherine Pioli fights fires in the summer, and travels the world and writes for CATALYST the rest of the year. 

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