Forever chemicals are everywhere. These burnt wood chips could help change that
Used in many household products, some highly toxic PFAS take a thousand years to break down
Forever chemicals are everywhere, from cookware to cosmetics to clothes to carpets. For decades, they've been building up in the environment and our water – and in our bodies.
Now Canadian researchers say they have developed a practical way to remove the toxic compounds from our drinking water.
"There's no natural way for this thing to break down," said Johan Foster, an associate professor of chemical and biological engineering in the University of British Columbia's Faculty of Applied Science and the senior researcher on the team that developed the technology.
"They have found [forever chemicals] in everything from glaciers to mountain lakes to killer whales."
But by soaking wood chips in an iron chloride solution, then burning them at a high temperature, Foster's team was able to produce a new type of activated carbon that can capture and destroy forever chemicals.
"We are purifying the water," said Pani Rostami, a UBC master's student who is working on the project. "We are turning something that is very bad for the environment, a pollutant, to something that is causing no harm."
The results by UBC researchers were recently reported in a peer-reviewed paper in Nature Communications Engineering.
Widespread use, widespread problem
Since the 1950s, forever chemicals have been used in a wide variety of household products and industrial processes for their water-repellent and stain-resistant qualities.
The term "forever chemicals" refers to a group of over 10,000 distinct synthetic compounds, formally classified as per- and polyfluoroalkyl substances (PFAS).
They are nearly impossible to break down through conventional methods, and have been building up in the environment for decades.
"It doesn't break down in the body, just sunlight is not going to break it down," said Foster. "So it just accumulates. It accumulates in the environment, in the water or in the human body."
PFAS are bioaccumulative, which means they're absorbed by living organisms faster than the body can break them down and excrete them.
"It's in all of us," said Jane Fowler, an assistant professor of environmental microbiology at Simon Fraser University. "We can detect it in all of our blood samples and breast milk and that kind of thing."
The forever chemical dilemma
Foster says forever chemicals have a unique and extremely stable chemical composition.
"It becomes very, very difficult to degrade because of that carbon-fluorine bond," said Foster. "It's a fantastic, strong bond, which makes it a great chemical, but also a forever chemical."
Carbon-fluorine bonds are among the strongest known to chemistry – and PFAS can have dozens of them. This makes them extremely hard to break down.
Under normal conditions, breaking the strong bonds within a PFAS molecule requires lots of energy, making destruction impractical.
"You heat [PFAS-contaminated water] to 370 C under a lot of pressure and they will start to degrade," said Foster. "But the problem in drinking water specifically, [PFAS are] in such small quantities that heating all of your drinking water to that temperature is just unrealistic."
Currently, the only option for treatment facilities to remove PFAS from drinking water is to capture them using technologies like activated carbon or ion exchange.
"Those technologies remove the PFAS and trap it from the drinking water supply, but don't eliminate the problem," said Inder Singh, director of quality control for Metro Vancouver water services.
"Because of the insidious nature of PFAS compounds, they are then simply discharged back into the environment."
Trap and destroy
The new method developed at UBC aims to capture and eliminate PFAS with no major energy inputs required.
"It brings in two technologies," said Upal Ghosh, a professor from the Dept. of Chemical Engineering at University of Maryland, Baltimore County.
"I'm excited to see those efforts going on … we want to have the capability to break down these compounds in the long term."
Essentially, the iron-soaked, burnt wood chips – or "biochar" – act as a more effective form of activated carbon, grabbing PFAS molecules out of the water. The iron then acts as a catalyst, making it easier to snap those strong carbon-fluorine bonds.
"The PFAS compound attaches to the catalyst and then a reaction basically degrades it into smaller and smaller innocuous compounds that won't affect the human body," said Foster.
When ground into a powder, the material was able to destroy over 85 per cent of perfluorooctanoic acid (PFOA), a common type of PFAS, within three hours. These results were collected under low levels of ultraviolet light to simulate ambient sunlight, but the reaction is only slightly less efficient in the dark.
"I think it's promising," said Fowler. "Not only can they pull it out of the water, they can also start degrading those PFAS molecules so that they're not just creating a new waste product."
The team is now looking to scale up their operation. They have found an industrial partner in the B.C. Interior to help produce the biochar, Foster said.
Health Canada makes 'rare' move to address PFAS
In a rare move last month, Health Canada published new, stricter objectives for PFAS levels in drinking water. Though non-binding, it marks a shift in policy from regulating each type of PFAS individually to addressing them as a group.
It follows the issuance of strict regulations in places like the United States and European Union.
Those new objectives are meant to supplement Health Canada's official guidelines, issued in 2018 and 2019, which focus on only a handful of individual PFAS molecules.
Those guidelines call for provinces and territories, which regulate drinking water quality, to limit levels of PFOS – a common type of PFAS – to 600 nanograms per litre. That is 150 times higher than the new U.S. regulation of just four nanograms per litre.
"In rare instances, and PFAS was one of those, the science is moving very, very fast," said Stephanie McFadyen, research manager of the water quality program at Health Canada.
McFadyen said the objectives are meant to communicate that new evidence to the provinces and territories while Health Canada continues to develop new guidelines – a process that typically takes four to seven years.
"So to not act, well, give the appearance anyway, of not acting … did not seem like a reasonable approach."
McFadyen emphasized that part of the problem has been a lack of data. Few municipalities have been regularly testing for PFAS in drinking water, though she said that is starting to change. In the meantime, Health Canada has relied on academic studies.
For instance, one study looking at tap water in Quebec found PFAS in 99.3 per cent of samples.
"It took everybody by surprise, I think," said McFadyen. "It's in everything and everywhere … I think probably, maybe only plastics compare to the scale of the problem."
Dozens of hot spots across Canada
In Canada, most PFAS hot spots are either in industrial areas, where they have been widely used, or around airports and Canadian Armed Forces bases.
"Anywhere where there's been firefighting training and they've used these firefighting foams," explained Fowler. "They used it in really high concentrations in those types of foams until fairly recently."
Many of these hot spots were highlighted in a CBC investigation in 2020.
Several Canadian cities have also made headlines in recent years due to high levels of PFAS in their drinking water.
McFadyen with Health Canada said that when it comes to drinking-water sources, almost all communities can be affected. Groundwater tends to be the most susceptible, but surface water can also experience contamination.
Metro Vancouver's 'unique' drinking water
In Metro Vancouver, however, drinking water comes from protected mountain reservoirs.
"Metro Vancouver's drinking water is quite unique… there's no industry, no commercial operation," said Singh at the Seymour-Capilano water treatment plant in North Vancouver. "So the only source of PFAS contaminants would be airborne transport. And unless there's some specific industry that's going to be putting that into the atmosphere, the risk is minimal."
Since Metro Vancouver started biannual testing for PFAS, levels have consistently been below detection limits.
Singh said that as long as those levels remain that low, there is little reason for Metro Vancouver to implement this kind of PFAS removal technology – but also acknowledged that the science is changing quickly, and the district has to be ready to change with it.
"It's a public safety, public health issue, and any prudent public utility will be responsive to those regulations and meeting those requirements."
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With files from Georgie Smyth and Quirks and Quarks