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Ralph D. Ludwig
Dr. Ludwig is a member of GWERD’s Applied Research and Technology Support Branch. He has a B.Sc. in Biology, and an M.Sc. and Ph.D. in Environmental Engineering from McGill University. Dr. Ludwig provides technical assistance to EPA’s regional offices and conducts field research in the area of in situ chemical redox manipulation/modification.
Dr. Ludwig’s research are is in situ chemical reduction. He is specifically focused on in situ chemical modification of aquifer formations to promote reducing reactions that transform or remove contaminants from solution. This has included the use of ferrous iron-based reductant solutions to form in situ reactive zones capable of passively treating groundwater contaminants, such as Chromium(VI) moving through the reactive zone under natural gradient conditions. He has also been involved in the performance monitoring of organicbased permeable reactive barrier systems that promote sulfate-reducing conditions for removal of heavy metals and arsenic.
Selected Publications
Ludwig, R.D., D.J.A. Smyth, D.W. Blowes, L.E. Spink, R.T. Wilkin, D.G. Jewett, and C.J. Weisener. (2009). “Treatment of Arsenic, Heavy Metals, and Acidity Using a Mixed ZVICompost PRB.” Environ. Sci. Technol., 43, 6: 1979–1976.
Ludwig, R.D., C. Su, T.R. Lee, R.T. Wilkin, and B.M. Sass. (2008). “In Situ Source Treatment of Cr(VI) Using an Fe(II)-Based Reductant Blend: Long-Term Monitoring and Evaluation.” J. Environ. Eng., 134, 8: 651–658.
Ludwig R., C. Su, T.R. Lee, R.T. Wilkin, S.D. Acree, R.R. Ross, and A. Keeley. (2007). “In Situ Chemical Reduction of Cr(VI) in Ground Water Using a Combination of Ferrous Sulfate and Sodium Dithionite.” Environ. Sci. Technol., 41: 5299–5305.
Su, C. and R.D. Ludwig. (2005). “Treatment of Hexavalent Chromium in Chromite Ore Processing Solid Waste Using a Mixed Reductant Solution of Ferrous Sulfate and Sodium Dithionite.” Environ. Sci. Technol., 39: 6208–6216.
Ludwig, R.D., R.G. McGregor, D.W. Blowes, S.G. Benner, and K. Mountjoy. (2002). A Permeable Reactive Barrier for Treatment of Heavy Metals.” Ground Water, 40, 1: 59–66.
McGregor, R.M., S. Benner, R. Ludwig, D. Blowes, and C. Ptacek. (2002). “Sulfate Reduction Permeable Reactive Barriers to Treat Acidity, Cadmium, Copper, Nickel, and Zinc: Two Case Studies. In Handbook of Groundwater Remediation Using Permeable Reactive Barriers. Elsevier Science.
Chapelle, F., J. Wilson, and R. Ludwig. “Redox Processes for Remediation of Chlorinated Hydrocarbons and Methyl tert-Butyl Ether.” In: Workshop on Monitoring Oxidation-Reduction Processes for Ground Water Restoration, Workshop Summary, Dallas, Texas – April 26–27, 2000 (PDF) (148 pp, 1.49 MB) (EPA/600/R-02/002) January 2002
Ludwig, R.D., M. Barcelona, and K. Piontek. “Redox Processes in Petroleum Hydrocarbon Site Characterization and Remediation.” In: Workshop on Monitoring Oxidation-Reduction Processes for Ground Water Restoration, Workshop Summary, Dallas, Texas –April 26–27, 2000 (PDF) (148 pp, 1.49 MB) (EPA/600/R-02/002) January 2002