Mushrooms could help breakdown PCBs, according to research funded by Spokane’s wastewater system
A city-funded study to see whether fungi can break down persistent industrial pollutants before they enter the Spokane River has come back with a resounding “maybe.”
Over the past year, researchers with The Lands Council, a local nonprofit environmental group, tried to grow various strains of mushrooms in sludge from city storm drains.
The goal was to see whether the fungi could survive in a polluted environment, and whether they might be able to eat polychlorinated biphenyls, or PCBs, a family of chemicals used in flame retardants, coolants and more until they were banned in 1979.
PCBs are believed to cause cancer, and in large enough quantities may impair many systems in the human body, according to the U.S. Environmental Protection Agency.
All eight species of mycelium, the technical name for the rooted part of the fungus that usually grows below ground, survived in jars where typical food like wood chips was mixed with storm drain sludge. Some species grew robustly, filling the jar, while others struggled more or showed some contamination from mold.
As for eating PCBs, the results were more mixed. Overall, concentrations of ten types of PCBs showed a statistically significant decrease, while concentrations of 19 other PCBs increased.
Mike Petersen, executive director of the Lands Council, said those results are exciting, even with the uncertainty.
“PCBs are really hard to break down and so the fact that this actually did something I think was kind of amazing,” he said. “And it did it in two months.”
The PCBs which had decreased concentrations were larger molecules that tend to have more severe health effects. Petersen speculated the fungi were able to break those down into smaller PCBs, which would explain why the concentration of some molecules increased.
“It actually seemed to have done something significant. That’s pretty exciting in a lot of ways,” Petersen said.
The research was funded with a $30,000 grant from the city to the Lands Council.
What makes the results interesting is that PCBs almost never degrade. Most efforts to mitigate their effects involve moving them from somewhere where they can accumulate in animals or people, like the Spokane River, to somewhere where they’ll be less harmful, said the city’s utilities spokeswoman, Marlene Feist.
“It’s promising from that perspective,” she said.
But it’s unlikely the city will fund extended research to hone in on how the fungi are interacting with the molecules and whether they’d be a viable solution, Feist said.
“It really probably belongs in a research institution,” she said.
Petersen would like to see more research in a few areas. One would be trying to grow the fungi in higher concentrations of stormwater sludge to see whether they might eat more of the harmful molecules.
“Fungi kind of train themselves to whatever they’re presented to eat,” he said. If researchers lowered the amount of wood chips available to them, they might start eating PCBs earlier and make more progress.
Another option would be to build storm gardens using some of the fungi species that were most effective, and seeing whether they remove PCBs from water before it enters the river. That approach would need to find a way to trap the stormwater with the fungi long enough for the fungi to eat the chemicals.
Feist said the city will talk with the Lands Council about possible paths forward.