Natural solution protects land, groundwater from toxic substances

The Researcher

University of Toronto researcher Courtney Toth

The Challenge

Protecting human and environmental health from hydrocarbon contamination

The Solution

Novel, green solution that ‘eats away’ at petroleum contaminants

The Outcome

The innovative technology is now being deployed at contaminated sites where oxygen is limited, including deep soils and groundwater

Petroleum-contaminated sites, such as old gas stations, number in the thousands across Canada. Postdoctoral researcher Courtney Toth helped develop a natural and affordable solution to tackle the problem.

Researcher develops cocktail of microbes that ‘eat’ some of the world’s most widespread contaminants

For the past several years, University of Toronto researcher Courtney Toth has been keeping a close eye on fermenters. But instead of brewing beverages like beer or wine, she’s growing a cocktail of microbes that ‘eat’ some of the world’s most widespread contaminants. 

Toth — a postdoctoral researcher working under the supervision of Professor Elizabeth Edwards in the Department of Chemical Engineering & Applied Chemistry at the University of Toronto — has helped develop anaerobic microbial cultures (mixtures of bacteria and other microscopic organisms that grow in the absence of oxygen) that completely break down a toxic class of petroleum hydrocarbons known as BTEX – benzene, toluene, ethylbenzene, and xylene. The innovative technology builds on decades of research and is now being deployed at contaminated sites where oxygen is limited, including deep soils and groundwater. In Canada alone, petroleum-contaminated sites, such as old gas stations and orphaned oil wells, number in the thousands. 

“Wherever we use petroleum products, there is a risk of hydrocarbon contamination. BTEX is especially hazardous when it enters groundwater systems, as it can spread far from the source of contamination. To protect human and environmental health, we need cost-effective, sustainable solutions that can clean it up,” said Toth. “That’s where our cultures really shine.” 

“The beauty of our technology is that it’s completely natural,” explained Toth, who is part of a multidisciplinary team of researchers across Canada tackling anaerobic hydrocarbon degradation. “It relies on species of microbes that have been able to break down BTEX and other hydrocarbons for millions, if not billions, of years. Now that we have an understanding of the microbiology and biochemistry behind these processes, we can employ them for our own use.” 

After conducting dozens of lab experiments, Toth and her team have shown that the cultures developed can reliably degrade BTEX, and are safe for use in the environment. Next, they scaled up the cultures to large volumes for field deployment. Specialized drilling equipment is used to inject the cultures deep underground into plumes of hydrocarbon contamination. It’s then up to the microbes to do the rest. 

“All we’re doing is increasing the number of active BTEX-degrading microbes,” said Toth, explaining that they will continue to grow and ‘feed’ on the contaminants until they are completely depleted. “It’s one of the least intrusive ways of treating a site.” 

Not only is the solution viable, it is a fraction of the cost of other remediation approaches that require excavation or multiple rounds of treatment. And by speeding up natural degradation processes, this technology could feasibly shave years off of remediation timelines and save millions of dollars in site-management costs. 

Due to rapid interest in the approach, the cultures are now being produced and distributed by Guelph-based remediation company SiREM under the brand name DGG™ Plus, in homage to microbiologist Dunja Grbić-Galić, who pioneered the field of anaerobic hydrocarbon degradation. Field tests are underway at five North American contaminated sites and early field data is mirroring the success of the lab results. Toth played a key role in obtaining federal approval to manufacture and sell the cultures in Canada. 

The innovative research has earned Toth the 2022 Mitacs Award for Commercialization, presented at a ceremony at the National Arts Centre in Ottawa on November 22, 2022. The award recognizes a Mitacs intern for their work in bringing an idea from research to market. 

Toth acknowledges that the project may not have happened without Mitacs’s support. She had just finished defending her PhD thesis when Professor Edwards invited her to work on scaling the cultures, but the project required funding. “I’m so honoured to be a part of this project and to work alongside an incredible team of scientists,” said Toth. “Mitacs was instrumental for making this possible and helping us along the path to commercialization.” 

Mitacs’s programs receive funding from valued partners across Canada. We thank the Government of Canada, the Government of Alberta, the Government of British Columbia, Research Manitoba, the Government of New Brunswick, the Government of Newfoundland and Labrador, the Government of Nova Scotia, the Government of Ontario, Innovation PEI, the Government of Quebec, the Government of Saskatchewan, and the Government of Yukon for supporting us to foster innovation and economic growth throughout the country. 

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