Our next webinar is scheduled for Thursday, March 28th, 2019 12:00 PM – 1:00 PM EDT, featuring Dr. David Freedman.
SiREM’s webinar series features guest speakers who are subject matter experts to provide the latest information on technology advances in environmental remediation and site characterization. The webinars will combine recent research and development activities for new and emerging contaminants and technologies with real word applications to characterize and remediate contaminated sites.
We hope you will join us for our next webinar:
Documenting Biodegradation when the Products are Difficult to Discern
For common groundwater contaminants such as chlorinated ethenes, demonstrating biodegradation activity based on detection of daughter products is straightforward, since the products are readily discernable from background sources. However, this is not the case for all contaminants. With chlorinated methanes (i.e., carbon tetrachloride, chloroform, and dichloromethane), for example, anaerobic reductive dechlorination is not the only degradation pathway. Dichloromethane is a significant product from carbon tetrachloride and chloroform but it does not undergo a significant level of reductive dechlorination. Instead, dichloromethane undergoes organohalide fermentation to products such as CO2 and organic acids, which are not unique to the parent compounds. Likewise, aerobic biodegradation of 1,4-dioxane yields products (e.g., CO2, soluble compounds, and biomass) that are not distinguishable from other processes. When it becomes necessary to provide evidence that these contaminants are undergoing biodegradation in situ, one way to do so is to employee 14C-labeled compounds in laboratory controlled experiments. Two examples will be highlighted. The first involves the use of 14C-chloroform to identify the products formed by KB-1 Plus, a commercially available bioaugmentation culture. The second involves use of 14C-1,4-dioxane with cultures that grow on the contaminant or cometabolize it following growth on propane, as well as with groundwater samples taken at several locations. Use of 14C-labeled compounds can provide valuable information about degradation pathways as well as the biodegradation rates.
Dr. David Freedman is a professor and chair of the Department of Environmental Engineering and Earth Sciences at Clemson University. He received his PhD in Environmental Engineering from Cornell University, where he worked with Jim Gossett on organohalide respiration of chlorinated ethenes and organohalide fermentation of dichloromethane. He started his academic career at the University of Illinois and moved to Clemson University where he has been since 1996. Dr. Freedman has received research support from the Strategic Environmental Research and Development Program, EPA, US DOE, US Army Construction Engineering Research Laboratory, US Air Force Office of Scientific Research, Westinghouse Savannah River Corporation, and numerous consulting firms. One of his current projects with SERDP is evaluating the potential for degradation activity of chlorinated ethenes in fractured rock at three Department of Defense sites.
Ms. Dworatzek is a Senior Manager of SiREM and an environmental microbiologist with advanced technical experience in laboratory treatability studies. Over the past 25 years she has conducted and overseen numerous bench-scale studies examining enhanced in situ remediation in groundwater. She has specific technical experience in the design of laboratory treatability studies, the scale up of growth of 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.