Categories: News & EventsWebinars

Webinar Series – Next Webinar, February 23, 2017

Our next webinar is scheduled for Thursday February 23, 2017 featuring Dr. Shaily Mahendra.

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:

Biodegradation of 1,4-Dioxane: Bacteria, Pathways, Co-contaminant Effects and Monitoring Tools

Dr. Shaily Mahendra (Professor, Department of Civil and Environmental Engineering, UCLA) will discuss: the challenges with current remediation techniques for cleanup of 1,4-dioxane contaminated sites, a culture which can grow using 1,4-dioxane as its only source of carbon and energy, and the role of monooxygenase enzymes in catalyzing 1,4-dioxane degradation. Sandra Dworatzek (SiREM) will provide an update on the work SiREM is doing to grow 1,4-dioxane cultures, testing the culture in laboratory microcosm studies and culture scale up for field applications.



1,4-Dioxane, a probable human carcinogen, is emerging as a contaminant of concern in water. Improper practices during manufacturing, use and disposal of solvents have resulted in the contamination of surface water and groundwater with 1,4-dioxane. Its high water solubility and low Kow and Koc values limit high-resolution detection methods and remediation using air stripping, thermal desorption, and soil vapor extraction inefficient for sites with large, dilute 1,4-dioxane plumes. While evidence for natural attenuation is growing, cleanup is likely to be challenging because 1,4-dioxane is often commingled with chlorinated volatile organic compounds (CVOCs) and most technologies that target CVOCs are not effective for 1,4-dioxane removal. Furthermore, CVOCs such as TCE, cis-1,2-DCE, 1,1-DCE and heavy metals such as Cu2+, Ni2+, Cd2+ and Cr6+, inhibit 1,4-dioxane biodegradation in the environment. Aggressive technologies, such as advanced chemical oxidation, efficiently degrade 1,4-dioxane, but they are costly and energy intensive, especially for pumping and ex-situ treatment. Indeed, biodegradation of 1,4-dioxane has been previously reported in a number of laboratory and field studies, yet reliable analytical tools to assess natural attenuation and bioremediation in the field are lacking. We recently developed a novel Compound Specific Isotope Analysis (CSIA) method for determining the enrichment of 13C and 2H in 1,4-dioxane. Pseudonocardia dioxanivorans, which can grow using 1,4-dioxane as its only source of carbon and energy, was isolated and characterized in our previous work. The role of monooxygenase enzymes in catalyzing 1,4-dioxane degradation was confirmed using several independent lines of evidence, and a biochemical degradation pathway was described. We have developed molecular biological probes targeting monooxygenase genes to serve as monitoring tools for 1,4-dioxane bioremediation in contaminated groundwater. These studies will provide mechanistic and quantitative data needed to change the landscape in 1,4-dioxane treatment technology by: 1) changing the industrial and regulatory perception of 1,4-dioxane biodegradability, 2) understanding treatment mechanisms, especially in contaminant mixtures; and 3) improving tools to validate natural or enhanced remediation effectiveness.

The Presenters:

Dr. Shaily Mahendra is an Associate Professor in the UCLA Department of Civil and Environmental Engineering, and a member of the California NanoSystems Institute and the Molecular Toxicology Program.
She received Ph.D. from University of California, Berkeley, and post-doctoral fellowship from Rice University. She recently won National Science Foundation CAREER Award, DuPont Young Professor Award, Northrop Grumman Excellence in Teaching Award, Samueli Fellowship, Hellman Fellowship, Poptech Science and Public Leadership Fellowship, and Environmental Science & Technology Excellence in Review Award. Her research areas are microbial processes in natural and engineered systems, applications of molecular and isotopic tools in environmental microbiology, environmental applications of nanomaterials, and biotransformation of water contaminants.

Sandra Dworatzek, M.Sc. Microbiology, University of Waterloo.
Sandra is a Senior Manager of SiREM and an environmental microbiologist with advanced technical experience in laboratory treatability studies. Over the past 23 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.

To view previously recorded webinars click here.

Pam Wood

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