Feature: Chemical Engineering
Special Report for International Year of Chemistry
Elizabeth Edwards has been a driving force in propelling bioaugmentation from pie-in-the-sky lab research to real-world practice.
By Stephen Strauss
First in a five part series profiling Canadian women in the chemical sciences and engineering in celebration of the International Year of Chemistry.
Over the past 17 years a super-energetic, sports-loving University of Toronto professor of chemical engineering has led a revolution in what was previously seen as a fundamentally flawed and over-hyped enterprise — adding bacteria to contaminated sites and then letting natural processes break noxious chemicals down into harmless sub-components.
Indeed, until Elizabeth Edwards was able to bridge the chasm between lab science’s promise and field science’s failures, “bioaugmentation” — the term used to describe the process — was routinely followed by the words “snake oil salesmen.”
“People would sell you a magic pixie dust that you were just supposed to sprinkle over a site and it would do all the clean up for you,” says Edwards in the midst of a work day so harried that she has had to skip lunch for an interview.
“It was just oversold and that is still happening today.”
Except, one has to quickly add, where Elizabeth Edwards has become involved. She is today a driving force in a university researcher/environmental consulting company collaboration that has taken the snake oil and pixie dust out of bioaugmentation in which naturally existing microbes are applied to the degradation of tetrachloroethene (PCE) and trichloroethene (TCE).
These compounds, which are widely used in dry cleaning and metal cleaning, have become synonymous with the unintended ecological consequences of 20th century chemical engineering. “The notion was that they were completely harmless,” says Edwards who speaks about her work both with a passion and with that most unusual of rhetorical flourishes — complete sentences. “They were inert; they didn’t burn; they didn’t react with anything. So after you cleaned your clothes you just could dump them out in back and let them evaporate.” While TCE and PCE did evaporate a little, what they mostly did is sink into the ground and then contaminate the groundwater underneath them.
How Edwards came up with a magic bacterial mix - which breaks the chlorinated chemicals down in the anaerobic world they inhabit - grows out of a life and career path that seemed destined from birth to first get a PhD and then turn research into practical application.
She grew up in Montréal, daughter of two McGill University professors. Her own career path was anything but straight forward when she entered McGill. “I liked math and I liked the environment,” she recalls, “and I thought for a while I would go into geology, but what changed my mind at the last minute was a chemical engineering brochure I saw one day which said ‘Versatility is the hallmark of chemical engineering.’ And I thought ‘yeah’ I don’t have to make up my mind, I can just do whatever chemical engineering is.” When she graduated there were no jobs in her field so she did a masters in biomedical engineering. Then she got a job at Seagrams Ltd. in Montréal learning how to grow micro-organisms for brewing processes and that led her to the belief that microbiology — particularly as it related to the environment — was her future. It was also in a way in her then-present, because at McGill she met her husband Aled Edwards, who is now a professor of biochemistry at the University of Toronto.
She then went off to get a PhD at Stanford — on the day of the interview she is proudly wearing a Stanford sweater. There her thesis was on the anaerobic biodegradation of toluene, benzene and xylene. Then, what is known in academe as the “two-body problem” arose. Her husband got a position at McMaster University in Hamilton and Edwards decided that it was going to be easier for her take a job in industry rather than seek one herself in an over-crowded academic work setting. So after hearing David Major, principal environmental scientist at Geosyntec Consultants in Guelph, give a talk on the efforts of his company to understand the biodegradation of chlorine compounds, she approached him for a job.
But there was also another motivation for going into industry. The born-from-the-womb academic wanted to subject her university research to practical scrutiny. “I wanted to see if there were indications of how it could be used in the field. I wondered, ‘is this really real, can it really happen?’” she says. So in 1992 Edwards found herself in a new city, completing her PhD thesis, working full time, pregnant with her third child, while looking after the other two.
“It was,” she explains with a dryness that could make vermouth seem soppy,“a challenging year.” And the bioremediation reality she encountered in the field was disheartening.
At some sites that Geosyntec was trying to clean up, nature’s chloride degradation biochemistry seemed to be working perfectly. At others nothing was occurring even after nutrients were added to stimulate the bacteria.
Edwards discussed the problem with Evan Cox, a consultant at Geosyntec and the two had a mini-eureka moment. The ecological presumption, based on previous experience with hydrocarbon decomposition, was that the chloride degrading microbes existed everyplace on earth. But maybe that wasn’t the case. Maybe what was happening was there were no effective PCE and TCE decomposing bacteria in some locales. To test the hypothesis Edwards took a batch of dirt from a site in Ontario where biodegradation was occurring, mixed it with a soil sample from New York State where it didn’t happen. She sealed the bottle, added a bit of hydrogen to make the mixture anaerobic and then observed what followed.
Within two days the chlorinated compounds which hadn’t broken down in 200 days were completely dechlorinated. “I thought holy moly, I can’t believe it,” says Edwards “and then I had to spend a lot of time proving to myself that it was true.”
What followed was a torrent of scientific research from her and others. There was a search for the most efficient biodegrading microbes. These turned out to be the Dehalococcoides which unlike other dechlorinating bacteria didn’t finish acting until they had completely turned TCE and PCE into non-toxic ethene. The genome for several Dehalococcoides species was also sequenced. This indicated that the Dehalococcoides were niche specialists which only thrived in the deoxygenated environments like those found in contaminated underground water. Even more compelling was the demonstration that their sole food stuff was chlorinated compounds.
This understanding combined to allow Edwards to create a bacterial culture specifically designed to rapidly and completely break down chlorinated compounds. She named it KB-1. The initials stand for “kick butt” which was the name her mother gave a beloved red pickup truck. “When I told my mom about what we had done, she said “oh, it’s like a kick butt culture,” laughs Edwards.
KB-1, a bioremediating anaerobic
microbial culture created by
Elizabeth Edwards, is injected
into the ground from a beer-keg-like
pressure canister at a site in eastern
Indiana, U.S., which is contaminated
with trichloroethene (TCE). TCE is the
most common industrial degreasing solvent,
used in all metal manufacturing and in the
What flowed from KB-1 has first been a new business enterprise for Geosyntec. It created SiREM, a company which uses bioaugmentation strategies to clean up chlorinated waste sites. Over 200 places in Canada, the U.S. and Europe have availed themselves of SiREM’s services and with a proof in place of the principle of bioaugmentation other firms have begun selling their own dechlorinating bio-cultures.
All of this has combined to create a paradigm shift in people’s view of the worth of bioaugmentation in general.
“I think it sounds hyperbolic to talk about a revolution taking place, but it actually is kind of true,” says Stephen Zinder, a Cornell University microbiologist who has worked closely with Edwards. “This is now how we deal with contaminated sites. And Elizabeth really helped us understand how the organisms worked in their environment.”
If Elizabeth Edwards is not solely responsible for bioaugmentation’s 21st century rehabilitation, she has been a key player in making it happen and for a very clear reason.
She keeps checking to see if what she is finding in her university laboratory is “really real” in nature. “What she has brought is an appreciation of the needs of the field. How do you reduce what you do to practice, not pure research, not pie-in-the-sky?” says Major. “And she has added to that real data about how the process works, not the bogus stuff people were coming up with before.”
So what lies ahead for the mistress of really, real bioaugmentation? “We are looking at other compounds, in particular fluorinated compounds like Teflon. The question is can we do anything to break them down,” she says. Not to mention ways of using anaerobic processes to generate ethene from waste products.
What has her journey into a world where biology meets man-made chemicals taught Edwards? “Evolution is our friend,” she reflects. “You have to look at sites or locations or places where whatever transformation you seek has been happening for many, many, many decades or centuries. There you will find microbes which will have evolved to do what you are looking for. The idea is to mine these historically impacted sites.” And that’s a really, real truth.
Stephen Strauss is a Toronto-based journalist who was for a long time the science writer at The Globe and Mail. More recently he has written a regular column for CBC.ca and numbers of features and news stories for Nature Biotechnology.
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