Project 5: Green Remediation by Solar Energy Conversion into Electrolysis in Groundwater

P5

Experimental Setup in Laboratory

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Significance: TCE, a chlorinated solvent, is among the most frequently encountered contaminants in soil and groundwater at regulated sites. The method we are developing to remove TCE from the environment is a simple, environmentally-friendly design.  The aims 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. Our project is also significant for improving the state-of-knowledge on electrochemical transformation of chemicals in water.

P52

Conceptual Design of Proposed Green Remediation Strategy (Click to Enlarge)

Our long-term goal is to develop novel, sustainable, solar-powered and environmentally-friendly 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 a mixture of contaminants. Two specific transformation mechanisms are evaluated: electrochemical reduction and chemical oxidation. We evaluated the enhancing effect of iron anode on electrolytic dechlorination of TCE. Coupling iron anode and a high surface area cathode (Cu foam) will achieve a TCE removal rate of greater than 99% in simulated groundwater. A patent application for the process has been submitted. Several variables, including electrode type (iron, MMO, copper foam), electrolytic system, electrode configuration, copper foam cathode thickness and flow rate were tested. The potential of the iron electrolysis system for the treatment of other possible groundwater contaminants, including chromium, selenate, nitrate and arsenic, is evaluated. In a mixture of contaminants, the ferrous species produced from the iron anode not only enhances the transformation of TCE on the cathode, but also facilitates transformation of other contaminants including dichromate, selenate, and arsenite. The results show that the overall system, comprising the electrode-based and electrolyte-based barriers, can be engineered as a versatile and integrated remedial method for a relatively wide spectrum of contaminants and their mixtures. Limestone column experiments are being conducted to evaluate TCE transformation by the process in a simulated karstic aquifer. Experiments are ongoing for further evaluation of iron electrolysis in a simulated karst aquifer.

Akram Alshawabkeh, Project Leader

Professor, Geotechnical and Geoenvironmental Engineering
Department of Civil and Environmental Engineering, Northeastern University
aalsha@coe.neu.eduwebsite

April Gu, Investigator

Associate Professor and College of Engineering Faculty Scholar
Department of Civil and Environmental Engineering, Northeastern University
april@coe.neu.edu 

Ingrid Padilla, Investigator

Associate Professor in Environmental and Water Resources Engineering
Civil Engineering, University of Puerto Rico at Mayaguez
padillai@uprm.edu

Dorothy Vesper, Investigator

Associate Professor, Department of Geology
West Virginia University
djvesper@mail.wvu.edu