Phil Dennis (Ontario) will present “Discovery and Tracking of a Novel Sulfolane-Degrading Bacterium through Laboratory and Field Studies,” and “How Are Nitrogen Compounds Attenuating at Your Site? Implications for Site Remediation and Climate Change” at RemTech 2022 (Banff) at the Fairmont Banff Springs in Banff, Alberta on October 12-14, 2022.

Phil Dennis is a Principal Molecular Biologist with more than 20 years of experience focused environmental microbiology, molecular genetic testing, enhanced bioremediation and technology commercialization. He currently directs the molecular testing services, next generation sequencing and is the innovation lead for SiREM’s research and development program. He has also played a leading role in developing relationships with many universities and serves on the Board for University of Waterloo Center for Microbial Research.

The Remediation Technologies Symposium 2022 (RemTech™ 2022) is the premier remediation technology transfer event for environmental professionals, encompassing the latest innovations in soil and groundwater remediation. RemTech 2022 will feature outstanding presentations, interesting keynote speakers, and numerous networking opportunities.

Considerable work is conducted in the field of contamination remediation and industrial pollutant treatments. RemTech™ 2022 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

The Environmental Services Association of Alberta (ESAA) was established in 1987, and with over two hundred member organizations it has grown to become one of Canada’s leading environment industry associations. ESAA members represent a wide cross section of the environment industry not just in Alberta but across the country. Its members are recognized as leaders in their field including: remediation, reclamation, air, water, waste, consulting, equipment, laboratory services, legal and regulatory services and industrial services.

Conference Participation

Discovery and Tracking of a Novel Sulfolane-Degrading Bacterium through Laboratory and Field Studies
Presenter: Phil Dennis, SiREM
Date/Time: Wednesday, October 12, 2022 from 4:20 p.m. – 4:50 p.m.
Phil Dennis’ co-authors are Jeff Robert, SiREM; and Savannah Volkov and Eric Nesbit, Geosyntec Consultants.


Nitrogen compound contamination of surface water and groundwater can originate from many sources including fertilizer application and production, human and livestock waste, and mining operations. Anthropogenic nitrate, ammonium and their breakdown products, such as nitrous oxide, have substantial negative environmental effects. Nitrate and nitrite are toxic to humans and are regulated in drinking water in Canada. Ammonium and nitrate contribute to eutrophication of natural water bodies. Nitrous oxide (N2O) is produced by partial denitrification and comprises approximately 6% of global warming emissions.

Microbial processes can convert problematic compounds into inert nitrogen gas, primarily via denitrification and anammox. Nitrification is also critical, functioning in tandem with denitrification to remove nitrogen mass. Dissimilatory reduction of nitrate to ammonium (DRNA) can reduce nitrogen mass in water or soil via volatilization of ammonia. To understand and optimize nitrogen compound remediation it is important to monitor not only the forms of nitrogen, but also microbial groups and functional genes critical to nitrogen metabolism. Multiple microbial and functional gene targets for nitrogen pathways are routinely monitored by quantitative polymerase chain reaction (qPCR) tests and next generation sequencing including denitrification, anammox bacteria, nitrification and DRNA. Other useful tests include compound specific isotope analysis (CSIA) which provides compelling evidence for ammonium and nitrate transformation. Also, total organic carbon and volatile fatty acids analysis can be used to determine if sufficient electron donor is available to drive denitrification or DNRA.

A former dry blend fertilizer plant, site near the Cape Fear River in North Carolina was characterized using a suite of molecular, analytical, and isotopic tests (NitroGen™) to assess intrinsic nitrogen removal processes. The site was contaminated with petroleum hydrocarbons, naphthalene, metals, and ammonia in groundwater at concentrations above regulatory standards. Ammonia exceeded the standard of 1.5 mg/L in all samples, with the highest concentration of 30.8 mg/L. The presence of nitrification, denitrification and anammox functional genes in groundwater at the site was confirmed by qPCR tests, and indicated multiple pathways for nitrogen mass removal that varied according to location. The potential for transformation of ammonium was confirmed by the detection of nitrification functional genes and anammox bacteria and was confirmed by 15N enrichment using CSIA. Even though nitrate was undetected, denitrification genes were detected, as were electron donors, supporting the possibility for denitrification. The data set provided compelling evidence that ammonia remediation was occurring at the site and likely utilized multiple pathways.

Once the existing pathways for nitrogen metabolism are understood at a site, a variety of approaches can be used to improve remediation performance including electron donor addition, to enhance denitrification and/or oxygen addition to enhance nitrification. Bioaugmentation has potential to introduce microbes with complete nitrogen pathways to enhance mass removal and reduce nitrous oxide emissions and global warming impacts. Effective monitoring of nitrogen metabolism and related parameters is an important first step to understand intrinsic bioremediation processes and to determine if enhanced bioremediation could improve system performance.

How Are Nitrogen Compounds Attenuating at Your Site? Implications for Site Remediation and Climate Change
Presenter: Phil Dennis, SiREM
Date/Time: Thursday, October 13, 2022 from 2:00 p.m. – 2:30 p.m.
Phil Dennis’ co-authors are Linda Eastcott and Arujala Thavendrarasa, Imperial Oil, Ltd.; Trent Key, ExxonMobil; Ximena Druar, Melody Vachon, Jennifer Webb, and Sandra Dworatzek, SiREM; Eva McLean, and Sylvain Hains, and Andrew Madison, WSP.


Sulfolane is a constituent of concern at former oil and gas sites where is used in the Sulfinol process for sweetening gas. Sulfolane is an emerging contaminant with chemical properties that promote transport in groundwater, including high solubility, low sorption potential and low volatility. While biodegradation of sulfolane under aerobic conditions has been demonstrated in laboratory and field-scale studies, it is critical to establish the site-specific intrinsic capacity for sulfolane biodegradation and to evaluate remedial strategies to enhance sulfolane biodegradation, for full-scale remedial design.

A former gas plant was piloted for enhanced attenuation via biosparging to increase the aerobic biodegradation of sulfolane in groundwater. Biosparging amended the groundwater with oxygen to enhance the growth of sulfolane-degrading microorganisms and increase sulfolane degradation rates. Field-scale biosparging resulted in sulfolane biodegradation to below criteria. To confirm and understand the observed decreases in sulfolane, multiple lines of evidence were employed, including traditional site data, culture-based techniques, and molecular biological tools  to identify and assess enhancement of sulfolane-degraders.

To propagate sulfolane degraders, a defined microbial growth media containing sulfolane was inoculated with site groundwater. Next generation sequencing (NGS) was used to characterize the culture’s microbial community and to assess changes due to varying sulfolane concentration. To isolate putative sulfolane degraders, the culture was plated on a differential media and colonies of a putative Rhodococcus were identified. Rhodococcus has not previously been reported to degrade sulfolane but is a known degrader of phenolic compounds and polycyclic aromatic hydrocarbons. The 16S rRNA sequence of the isolate was used to develop a quantitative polymerase chain reaction (qPCR) test used to quantify this microbe in the culture and in site groundwater.

Assessment of the site groundwater microbial community by qPCR indicated increases in total microbial abundance by over 100-fold in response to biosparging, while NGS indicated a shift to a more aerobic microbial community. The putative Rhodococcus isolate was tracked via the developed qPCR test and its abundance was positively correlated of with the presence of sulfolane and biosparging.

In summary, we have developed an enrichment culture capable of degrading sulfolane, identified a novel putative sulfolane-degrader, developed and demonstrated a qPCR assay for in situ tracking of this microbe and corelated it’s abundance with zones with high sulfolane degradation rates. Ongoing work to sequence the genome of the novel isolate as well as tests to identify genes involved in the degradation of sulfolane will be discussed.

 More Information

About the event: RemTech – ESAA
About the Environmental Services Association of Alberta: ESAA
For consultation regarding Nitrogen Compounds and Novel Sulfolane-Degrading Bacterium, contact Phil at
Learn more about Phil: Phil Dennis | LinkedIn