“Practical Assessment and Optimization of Redox-Based Groundwater Remediation Technologies” by Dr. Paul Tratnyek and Dr. Richard Johnson

Many approaches to remediation of contaminated groundwater rely on contaminant degradation processes that are, directly or indirectly, based on redox reactions. Predicting and optimizing such processes requires reliable methods for characterizing in situ redox conditions, but the existing methods (such as ORP measurement) have repeatedly been shown to be inadequate. Recent research has taken a “chemical probe reaction” approach, which involves injecting (e.g., by a push-pull test) probe/indicator substances that react with the medium and monitoring this reaction, usually spectrophotometrically. The probe response can be related to contaminant degradation (measured independently) and then applied at future/field site for predicting the overall performance of in situ processes for contaminant attenuation. This webinar summarized proven and innovative approaches for evaluating in situ redox conditions, comparing their strengths and limitations, and discussing some promising developments for further improvements.

Dr. Paul G. Tratnyek is a professor in the Institute of Environmental Health at the Oregon Health & Science University. His research interests are associated with a wide range of oxidation-reduction reactions that occur in the environment, and the contribution of these reactions to the fate of organic pollutants. In most of his work, the focus is on pathways, kinetics, mechanisms and other fundamental molecular aspects of environmental chemistry. His research includes some of the earliest work on chemical reduction of contaminants, especially zero-valent iron. He is the principal investigator on several past and ongoing projects funded by SERDP related to aspects of abiotic natural attenuation, in situ chemical reduction, in situ chemical oxidation and redox characterization. Dr. Tratnyek received a Bachelor’s degree in Chemistry from Williams College and a Ph.D. in Applied Chemistry from the Colorado School of Mines.

Dr. Richard L. Johnson is a professor in the School of Public Health at the Oregon Health & Science University. His recent research has centered on large-scale studies of groundwater contamination and diagnostic tools for characterization of in situ remediation processes. In addition, for more than 20 years, Dr. Johnson has emphasized the coupling of physical and numerical models to examine the transport and fate of chemicals in the subsurface. He has extensive field experience in a range of oxidation- and reduction-based in situ remediation technologies including chemical reduction with zero-valent iron. Dr. Johnson received a Bachelor’s degree in Chemistry from the University of Washington, and M.S. and Ph.D. degrees in Environmental Science from the Oregon Graduate Center.