Electrochemical transformation of an aged tetrachloroethylene contamination in realistic aquifer settings

Bente Højlund Hyldegaard*, Rasmus Jakobsen, Lisbeth M. Ottosen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Electrochemical removal of chlorinated ethenes in groundwater plumes may potentially overcome some of the challenges faced by current remediation technologies. So far, studies have been conducted in simplified settings of synthetic groundwater and inert porous matrices. This study is a stepwise investigation of the influence of field-extracted groundwater, sandy sediment and groundwater aquifer temperatures on the removal of an aged partially degraded contamination of tetrachloroethylene (PCE) at a typical groundwater flow rate. The aim is to assess the potential for applying electrochemistry at contaminated sites. At a constant current of 120 mA, pH and conductivity were unaffected downgradient the electrochemical zone. Major groundwater species were reduced and oxidized. Some minerals deposited, others dissolved. Hydrogen peroxide, a strong oxidant, was formed in levels up to 5 mg L−1 with a limited distribution into the sandy sediment. Trichloromethane was formed, supposedly by oxidation of organic matter in the sandy sediment in the presence of chloride. The more realistic the settings, the higher the PCE removal, bringing concentrations down to 7.8 ± 2.3 μg L−1. A complete removal of trichloroethylene and cis-1,2-dichloroethylene was obtained. The results suggest that competing reactions related to the natural complex hydrogeochemistry are insignificant in terms of affecting the electrochemical degradation of PCE and chlorinated intermediates.
Original languageEnglish
Article number125340
JournalChemosphere
Volume243
Number of pages10
ISSN0045-6535
DOIs
Publication statusPublished - 2020

Keywords

  • Electrochemistry
  • Chlorinated ethenes
  • Groundwater
  • Sandy sediment
  • Remediation
  • Applied potential

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