Sandra Dworatzek (Ontario) will present “Advances in Anaerobic Benzene Bioremediation: Microbes, Mechanisms, and Biotechnologies” at Virtual Remediation Technologies (RemTech) 2020 at 13:50 on October 15, 2020.

Sandra’s co-presenters are Jennifer Webb, (SiREM), Elizabeth Edwards, Nancy Bawa, Shen Guo, Courtney Toth, (University of Toronto), Kris Bradshaw, Rachel Peters, (Federated Co-operatives Ltd.), and Krista Stevenson, (Imperial Oil).

Sandra is a Principal Scientist with more than 25 years of experience in bioremediation of chlorinated solvents, petroleum hydrocarbons, emerging contaminants and other recalcitrant compounds. She has specific technical experience in the design of laboratory treatability studies, the scale up of growth of aerobic and anaerobic microbial cultures for bioaugmentation laboratory and field pilot tests, and evaluation of aerobic and anaerobic bioremediation, zero valent iron and chemical oxidation technologies in the laboratory. She currently provides senior technical oversight of laboratory treatability studies and the development and scaleup of new bioaugmentation cultures, including novel cultures for BTEX compounds under anaerobic conditions and aerobic 1,4-dioxane bioremediation. Sandra currently is the industry lead on a Genome Canada funded project for the commercialization of anaerobic BTEX degrading cultures.

The Remediation Technologies Symposium 2020 (RemTech™ 2020) is the premier remediation technology transfer event for environmental professionals, encompassing the latest innovations in soil and groundwater remediation. Building on the overwhelming success of last year’s event, RemTech™ 2020 is expected to exceed the standards set by its predecessor. Offering a larger, more diversified program, with additional keynote speeches and networking sessions, this is an event you won’t want to miss! Considerable work is conducted in the field of contamination remediation and industrial pollutant treatments. RemTech™ 2020 provides a forum for industry experts to present these leading-edge technologies. Co-sponsors and participating organizations include government, academic institutions, and private sector organizations active in site remediation, research and application.

Established in 1987, the Environmental Services Association of Alberta (ESAA) is one of Canada’s leading business associations with over 210 member companies. Dedicated to building a strong environmental industry, ESAA is an industry association with a business approach in providing programs that lead to its members’ corporate success.


Benzene, Toluene, Ethylbenzene and Xylene (BTEX) are widespread groundwater pollutants. Groundwater contamination with benzene is of particular concern due to its persistence in anoxic environments and confirmed carcinogenicity. Intrinsic anaerobic processes impact the fate of BTEX as well as other hydrocarbons at petroleum contaminated sites. Ongoing applied research has shown that anaerobic bioremediation processes represent viable options for plume control and site cleanup for BTEX. Benzene, the most toxic of these compounds, is also the most challenging for bioremediation, because the requisite microorganisms are relatively slow growing and reaction mechanisms are not well understood. Thanks to molecular genomics, the microorganisms responsible for benzene transformation have been identified and bioaugmentation cultures are now being grown in volumes sufficient for field application.

This presentation highlights significant milestones in characterizing anaerobic benzene biodegradation and their applications to developing better groundwater bioremediation solutions. It has recently been documented that anaerobic benzene biodegradation is catalyzed by a very narrow subset of microorganisms. Two such microbes reside in a methanogenic consortium (DGG-BTM; harbors Deltaproteobacteria ORM2) and a nitrate-reducing consortium (NRBC; harbors Peptococcaceae sp. Pepto-Ben). ORM2 and Pepto-Ben-like microbes have been detected in almost every established benzene-degrading enrichment culture worldwide and are frequently present in benzene-contaminated groundwater. In nature, however, their concentrations are often several orders of magnitude too low to contribute to active benzene biodegradation. Indeed, this emphasizes that effective anaerobic benzene bioremediation technologies should aim to enrich or augment ORM2 and Pepto-Ben-like microbes in situ.

Results from laboratory treatability studies demonstrated enhanced benzene biodegradation rates with DGG-BTM bioaugmentation and provided information to aid in field pilot-test design. One field pilot-test performed in November 2019 at a site in Saskatchewan  included three injection points, two of which received up to 10 liters of the DGG-BTM culture. A third injection point  received killed culture, which will serve as a control to rule out if dead cells, or media components, can promote benzene degradation. It is anticipated that benzene degradation rates will be accelerated in situ through bioaugmentation as observed in corresponding treatability studies. Two additional field applications (one in October 2019 and one in April 2020) are also being monitored. These first-to-field projects will establish clear guidelines and approaches for using these novel bioaugmentation cultures, including a better understanding of dosing requirements, timeframes for obtaining results and ranges of conditions over which the cultures are effective. As with chlorinated solvents, bioaugmentation for BTEX compounds has the potential to decrease remediation time frames and increase the range of sites to which bioremediation is applicable providing a much-needed, cost-effective alternative for BTEX remediation in groundwater.

More Information

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