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Significance: Our long-term goal is to develop novel, sustainable, solar-powered and environmentally-friendly electrochemical technologies for remediation of contaminated groundwater, especially in karst regions. We will use solar panels to apply low direct electric currents through electrodes in wells to manipulate groundwater chemistry by electrolysis. Our target contaminants are chlorinated solvents, specifically trichloroethylene (TCE), but the process will also be designed to treat other common groundwater contaminants and their mixtures. Our goals are relevant to the EPA’s strategic plan for compliance and environmental stewardship, which strives for cleanup programs that use natural resources and energy efficiently, reduce negative impacts on the environment, minimize pollution at its source, and reduce waste to the greatest extent possible.
Specific aims: In this project, we measure simultaneous transformation of TCE and a mixture of contaminants (e.g., chromium, selenate, nitrate and arsenic) by electrochemically-induced reduction and oxidation in groundwater. Chemical transformation is dependent on the ratio of flow rate to the electric current. Our system couples iron anode and a high surface area cathode (Cu foam) to remove all dissolved TCE from simulated groundwater while improving transformation of other contaminants including dichromate, selenate, and arsenite (Mao et al. 2011; Mao et al. 2012a; Mao et a. 2012b). A batch and flow-through undivided electrochemical systems are developed to support the electrochemically-induced oxidation (Electro- Fenton Reaction) of TCE (Yuan et al. 2012; Yuan et al. 2013). By a novel two electrode system with polarity reversal (Rajic et al. 2014) and optimized electrode arrangement with the use of proper cathode materials (Rajic et al. 2015a; Rajic et al. 2015b) we improve both electrochemical reduction and oxidation to remove TCE from groundwater. Further, we will investigate the performance of the technology in the presence of naturally occurring substances (e.g. humic substances, chlorides) and ability to degrade other commonly found groundwater contaminants and species (di-2-ethylhexyl phthalate or DEHP, nitrates etc.) along with TCE.
In the project, we will also investigate the pathways of electrochemically-induced degradation and their associated effects on groundwater toxicity to ensure the efficiency of the electrochemical processes in transformation of individual and mixtures of contaminants. The change in toxicity during the course of contaminant degradation in batch experiments will be measured using a newly-developed mechanistic toxicogenomics-based assay using gfp-fused real time reporter whole-cell libraries of E. coli and yeast (Onnis-Hayden et al. 2009; Gou et al. 2010; Gao et al. 2012; O’Connor et al. 2012). The correlation between the transformation products identified and the variations of toxicity levels and mechanisms during the course of the electrochemically-induced transformation will disclose the potential causal agents of toxicity along the chemical transformation pathway.
Project’s final goal is field implementation of developed electrochemical systems and in order to facilitate translating the process from laboratory scale to full scale application, we will implement and measure the performance of the process in a small field-scale test using a single- or multiple-well. Treatment units in the wells will be connected to solar panels/controllers and different operation modes will be tested and observations wells will be used to monitor changes.
Akram Alshawabkeh, Project Leader
April Gu, Investigator
Associate Professor and College of Engineering Faculty Scholar
Department of Civil and Environmental Engineering, Northeastern University
Ingrid Padilla, Investigator
Associate Professor in Environmental and Water Resources Engineering
Civil Engineering, University of Puerto Rico at Mayaguez
Dorothy Vesper, Investigator
Associate Professor, Department of Geology
West Virginia University