The purpose of this industrial PhD research project was to develop electrochemical zones for in situ degradation of chlorinated solvents and degradation products. Literature indicates that fast electrochemical reduction and oxidation of chlorinated solvents on the electrodes can be obtained and that reactants can be generated, subsequently contributing to the contaminant degradation. Focus of the project was on intelligent use and combination of different electrochemical processes to optimize the zone for efficient degradation of the chlorinated solvents in field-realistic systems.
Chlorinated solvents have been widely used in e.g. dry-cleaning and metal processing. Due to spills, leakage etc., the chlorinated solvents have been introduced to the environment. Contamination of chlorinated solvents now threatens the quality of the Danish drinking water resource and poses a health risk to its consumers. Thus, protecting the groundwater from this group of contaminants is important. Unfortunately, the compound’s properties challenge the current treatment systems, e.g. pump-and-treat (P&T) systems commonly used for keeping plumes from reaching water supply wells. However, these treatment facilities are long-term solutions with a significant carbon footprint, limited efficiency towards the chlorinated degradation products and generation of a secondary waste stream.
Development of an alternative solution to P&T for protection of the drinking water resource is in request by regions and private landowners in that P&T facilities are effective at hydraulic containment, but not at contaminant mass removal. In the Capital Region alone, 67 P&T facilities are currently operating, and more are expected in the years to come. Similar trends are seen for the remainder of the regions in Denmark. Furthermore, there is a global demand for such an alternative solution, especially in North America.
This applied research project contributes with valuable insight into the governing degradation processes in field-realistic systems, influence of natural hydrogeochemistry and groundwater temperatures on the electrochemical removal of the chlorinated solvents, and the resulting changes on the hydrogeochemistry induced by the established electrochemical zones.
Supervisors: Lisbeth M. Ottosen (DTU Byg), Eline B. Weeth (COWI A/S), Lone T. Karlby (COWI A/S), Lars Nissen (COWI A/S), Rasmus Jakobsen (GEUS), David B. Gent (US Army Corps of Engineers), Niels D. Overheu (Capital Region of Denmark).
Download the PhD thesis