Jeff Roberts (ON) will present “Applications of Anaerobic Petroleum Hydrocarbon Bioremediation” and “Monitoring Metals/Metalloid Reduction and Their Impacts in Aquatic Environments Through Molecular Genetic Tools” at the Remediation Technologies Symposium (RemTech 2021) in Banff Alberta, on 13-15 October 2021.
His co-presenters for “Applications of Anaerobic Petroleum Hydrocarbon Bioremediation” are Sandra Dworatzek & Jennifer Webb (SiREM), Elizabeth Edwards, Ph.D., O.C., Nancy Bawa, Shen Guo & Courtney Toth, Ph.D., (University of Toronto), Kris Bradshaw & Rachel Peters (Federated Co-operatives Ltd) and Krista Stevenson, Colette McGarvey & Ada Wang (Imperial Oil).
Jeff’s co-presenters for “Monitoring Metals/Metalloid Reduction and Their Impacts in Aquatic Environments Through Molecular Genetic Tools” are Phil Dennis (SiREM), Silvia Mancini, Ph.D., Andrew Holmes, Ph.D. & Rachel James (Geosyntec Consultants).
Jeff Roberts is the Operations Manager at SiREM with extensive technical experience in the laboratory assessment and field implementation of soil, sediment and groundwater remediation technologies at sites containing contaminants including chlorinated solvents, petroleum hydrocarbons, emerging contaminants and other recalcitrant compounds. Over the past 18 years he has conducted and managed hundreds of bench-scale batch and column treatability studies and has technical experience in the growth, scale up and field implementation of several anaerobic microbial cultures for bioremediation remedies. Jeff has several years of passive sampling experience and was a lead member in the development of the SP3™ sampler.
The Remediation Technologies Symposium 2021 (RemTech™ 2021) is the premier remediation technology transfer event for environmental professionals, encompassing the latest innovations in soil and groundwater remediation. Considerable work is conducted in the field of contamination remediation and industrial pollutant treatments. RemTech™ 2021 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 is a business association with a business approach to providing programs leading to its members corporate success! Since it has been established ESAA has continued to provide its members with educational publications and conferences much needed in the ever-changing environmental industry, as well as providing important networking opportunities. ESAA is committed to promoting its many members and their services. ESAA is proud to serve its member organizations!
Applications of Anaerobic Petroleum Hydrocarbon Bioremediation
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.
Recent advancements in molecular genomics have allowed us to identify the microorganisms responsible for anaerobic benzene, toluene and xylene (BTX) transformation and SiREM has commercialized an anerobic BTX culture (DGGTM Plus) for field application. The microbial composition of DGGTM Plus is relatively complex (i.e., not a pure culture) due to its origin as enrichments from diverse natural microbial communities. DGGTM Plus is a blend of three separately grown cultures that are comprised of mixture of prokaryotic Bacteria and Archaea. Anaerobic hydrocarbon-degrading consortia rely on a synergistic web of activities of different groups of microorganisms to ultimately achieve the complete degradation of BTX to innocuous products.
Based on the microbial community composition and metagenome of the cultures (Devine, 2013; Luo et al., 2016; Toth et al., 2021), the consortium has the predicted (functional) capability of participating in the following biogeochemical pathways:
- Fermentative BTX degradation (Deltaproteobacteria ORM2, Desulfosporosinus, and Peptococcaceae)
- Fermentation of a range of organic compounds
- Fermentation of dead microbial biomass (Ca. Nealsonbacteria, and others)
- Facultative sulfate reduction (Deltaproteobacteria ORM2, Peptococcaceae, Desulfovibrio, Desulfobacca, and others)
- Metals reduction (Geobacter)
- Facultative aerobic metabolism of organic compounds (minor organisms including Pseudomonas, and others)
- Methanogenesis (Methanosaeta, Methanoregula, Methanomethylovorans, and other methanogenic archaea)
Results from laboratory treatability studies demonstrated bioaugmentation promoted enhanced benzene biodegradation rates 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 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) with DGG-B™ and one field injection (Summer 2020) with DGG™ Plus are also being monitored.
These first-to-field projects using these novel bioaugmentation cultures, are providing 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.
Monitoring Metals/Metalloid Reduction and Their Impacts in Aquatic Environments Through Molecular Genetic Tools
Molecular genetic tools including targeted quantitative polymerase chain reaction (qPCR) tests and next generation sequencing (NGS) can be used to better understand and to optimize microbial communities involved in reduction of metals and metalloids. NGS provides comprehensive microbial profiles of a test sample including both metal and non-metal reducing microorganisms. Whereas qPCR methods provide more specific and quantitative information by targeting functional genes directly involved in metals/metalloid metabolism.
Treatment of dissolved metals can involve direct microbial reduction, that reduces solubility and toxicity, for example the reduction of selenate to elemental selenium or hexavalent chromium conversion to trivalent chromium. The use of qPCR allows quantitative monitoring of specific genes involved in metal reduction processes such as selenium reductases, or mercury reductases. Selected metals and divalent cations (e.g., arsenic, zinc) can be precipitated as metal sulfides, this process is driven in part by sulfate reducing microorganisms, which can be monitored by qPCR. NGS can be used to monitor important microbial groups involved in metal treatment processes such as sulfate reducers, groups known to directly precipitate metals and to monitor other members of microbial communities relevant to aquatic systems such as nitrate reducers.
The combination of NGS and qPCR can vastly increase our ability to understand how microbiology impacts metals treatment processes. The deployment of molecular tools at metal-impacted sites can aid in the ongoing monitoring of impact assessment, as well as performance assessment of remedial water treatment and source control technologies and alert operators to upset conditions that could lead to increased ecological impacts. Molecular tools can also enhance ongoing monitoring of water treatment processes including solid bed reactors, providing valuable operational feedback to inform optimization of amendment delivery, such as electron donors, or other nutrients, and bioaugmented microorganisms. NGS can also be used to assess the ecological impacts of metals, using environmental DNA (eDNA) approaches which can be performed on water and sediment samples to monitor biota such as fish, aquatic insects and amphibians. Surveys using eDNA are relatively easy to perform, and inexpensive, when compared to traditional bioassessments that require collection and identification of a wide variety of organisms such as benthic macroinvertebrates.
This presentation will cover how increased knowledge of metal/metalloid metabolic pathways combined with the growing array of molecular tools is increasing our ability to advance biotreatment of metals/metalloids and to assess their environmental impacts.
About the event: https://esaa.org/remtech/
About ESAA: https://esaa.org/
For consultation regarding SiREM’s bioaugmentation cultures for BTEX remediation, contact Jeff (email@example.com) or Sandra (firstname.lastname@example.org).
For consultation on molecular tools for monitoring for metals and metalloids, contact Jeff (email@example.com) or Phil (firstname.lastname@example.org).
Learn more about Jeff: https://www.linkedin.com/in/jeff-roberts-209a048/