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This SERDP and ESTCP webinar presents results on remediating groundwater contaminated with 1,4-dioxane mixed with other contaminants. Specifically, investigators will present the use of two technologies (linked membrane reactors and coupled electrochemical treatment and biological oxidation) to demonstrate effective reduction of 1,4-dioxane, 1,1,1-trichloroethane (TCA), trichloroethene (TCE), and/or other chlorinated solvents.
“Synergistic Reductive Dechlorination of 1,1,1-Trichloroethane and Trichloroethene and Aerobic Biodegradation of 1,4-Dioxane” by Dr. Bruce E. Rittmann (SERDP Project Webpage)
Groundwater co-contaminated with 1,4-dioxane and TCA and/or TCE is common. A pressing need for DoD is a means to simultaneously remove 1,4-dioxane, TCA, and TCE. As part of this SERDP effort, we proposed and tested a synergistic platform featuring anaerobic TCE/TCA reduction in a H2-based Membrane Palladium-film Reactor (MPfR) followed by 1,4-dioxane biodegradation in an O2-based Membrane Biofilm Reactor (MBfR). As discussed in the presentation, our experimental evaluations of TCE/TCA reduction in the H2-based MPfR documented rapid and selective reductive dechlorinating TCE/TCA to ethane. Likewise, 1,4-dioxane was mineralized in an O2-based MBfR to which we delivered ethane. We then configured the synergistic platform by linking the TCE/TCA-reducing H2-MPfR with a 1,4-dioxane-oxidizing O2-MBfR in sequence. During 130 days of continuous operation, 1,4-dioxane and minor by-products from the H2-MPfR were fully biodegraded through oxidation in the O2-MBfR. Results of the continuous operation period showed that all contaminants could be removed to below their Maximum Contaminant Levels or detection limits. In summary, we demonstrated proof-of-concept for removing TCE, TCA, and 1,4-dioxane without significant accumulation of toxic intermediates in a synergistic platform featuring a H2-based MPfR for Pd-catalyzed TCE/TCA reduction followed by an O2-based MBfR for biological degradation of 1,4-dioxane.
“Bioelectrochemical Treatment of 1,4-Dioxane in the Presence of Chlorinated Solvents” by Dr. Jens Blotevogel (SERDP Project Webpage)
Biodegradation processes are challenged to reduce 1,4-dioxane groundwater concentrations to low- or sub-ppb regulatory limits, especially in the presence of inhibiting chlorinated solvents. This project supports SERDP’s efforts to reduce DoD liabilities by developing a sustainable technology for cost-effective remediation of 1,4-dioxane in mixed plumes. Electrochemical water treatment is an emerging technology for the destruction of persistent organic pollutants. This webinar will present the findings of laboratory-scale flow-through reactor studies, provide treatment design, process and sustainability considerations, and discuss technology scale-up for field implementation of this technology. Using commercially available mesh electrodes, electrochemical water treatment can be implemented both ex situ and in situ. To increase the efficiency of this advanced oxidation process, electrochemical treatment can be coupled with biological degradation. The synergistic benefits that can be harnessed through combined bioelectrochemical treatment originate from microbial utilization of anodically generated oxygen as electron acceptor, concurrent electrochemical removal of inhibiting chlorinated solvents, and transformation of 1,4-dioxane into more readily degradable, growth-supporting organic intermediates. As discussed in the presentation, results of combined bioelectrochemical treatment include capital and operational costs that are about one order of magnitude lower compared to electrochemical oxidation only, while achieving the strict regulatory limits for 1,4-dioxane.
Dr. Bruce E. Rittmann is Regents’ Professor of Environmental Engineering and Director of the Biodesign Swette Center for Environmental Biotechnology at Arizona State University. His research focuses on the science and engineering needed to “manage microbial communities to provide services to society.” Dr. Rittmann is a member of the National Academy of Engineering; a Fellow of the American Association for the Advancement of Science, Water Environment Federation, International Water Association, Association of Environmental Engineering and Science Professors, and National Academy of Inventors. He is also a Distinguished Member of the American Society of Civil Engineers. Dr. Rittmann is the co-winner of the 2018 Stockholm Water Prize. He has published over 730 journal articles, books, and book chapters, and he has 17 patents.
Dr. Jens Blotevogel is a Research Assistant Professor in the Department of Civil and Environmental Engineering at Colorado State University (CSU) and Co-Director of CSU's Center for Contaminant Hydrology. Dr. Blotevogel’s research revolves around the fate of emerging contaminants, conducting laboratory- and field-scale studies to elucidate their degradation in both natural and engineered systems. He has developed sustainable water treatment technologies, theoretical models for contaminant degradation prediction, and various advanced analytical methods with a focus on high-resolution accurate mass spectrometry. Besides 1,4-dioxane and chlorinated solvents, Dr. Blotevogel is currently working on solutions for managing per- and polyfluoroalkyl substances, nitroaromatic compounds, perchlorate, and oil & gas produced water. He holds a Doctoral degree in Environmental Chemistry from CSU, a Diploma in Environmental Engineering from the Technical University Berlin, and has worked for several years as project engineer for in situ groundwater remediation.