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Title: In Situ Dechlorination of TCE During Aquifer Heating

Abstract

Laboratory and field efforts were undertaken to examine trichloroethene (TCE) dechlorination as a function of temperature as an aquifer is heated to temperatures approaching boiling. Experiments were conducted using sediment samples during electrical resistance heating (ERH) treatment at the Fort Lewis East Gate Disposal Yard, which contains non-aqueous phase TCE and hydrocarbon contamination. Laboratory microcosms with these sediments showed TCE dechlorination at 70oC with measured products of acetylene, ethene, and ethane, indicating an abiotic component of the degradation. In contrast, TCE was dechlorinated to cis-1,2-dichloroethene in experiments at 10oC, likely by biological reductive dechlorination. The observed products at 70oC suggest dechlorination catalyzed by reduced sediment iron. Indications of in situ dechlorination were observed in periodic groundwater samples collected during field-scale electrical resistance heating from an average ambient temperature of about 19oC to near boiling. Dechlorination indicators included an increase in chloride concentration at the onset of heating and observation of acetylene, ethene, and methane at elevated temperatures. The data collected in this study suggest that dechlorination can occur during ERH. The overall cost-effectiveness of ERH may be enhanced by fortuitous in situ dechlorination and, potentially, can be further enhanced by specifically designing and operating ERH to maximize in situ dechlorination.

Authors:
; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
918459
Report Number(s):
PNNL-SA-48752
Journal ID: ISSN 1069-3629; GWMREV; 400403209; TRN: US200819%%286
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Ground Water Monitoring and Remediation, 27(2):96-105; Journal Volume: 27; Journal Issue: 2
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; AMBIENT TEMPERATURE; AQUIFERS; DECHLORINATION; HEATING

Citation Formats

Truex, Michael J., Powell, Thomas, and Lynch, Kira P.. In Situ Dechlorination of TCE During Aquifer Heating. United States: N. p., 2007. Web. doi:10.1111/j.1745-6592.2007.00141.x.
Truex, Michael J., Powell, Thomas, & Lynch, Kira P.. In Situ Dechlorination of TCE During Aquifer Heating. United States. doi:10.1111/j.1745-6592.2007.00141.x.
Truex, Michael J., Powell, Thomas, and Lynch, Kira P.. Sun . "In Situ Dechlorination of TCE During Aquifer Heating". United States. doi:10.1111/j.1745-6592.2007.00141.x.
@article{osti_918459,
title = {In Situ Dechlorination of TCE During Aquifer Heating},
author = {Truex, Michael J. and Powell, Thomas and Lynch, Kira P.},
abstractNote = {Laboratory and field efforts were undertaken to examine trichloroethene (TCE) dechlorination as a function of temperature as an aquifer is heated to temperatures approaching boiling. Experiments were conducted using sediment samples during electrical resistance heating (ERH) treatment at the Fort Lewis East Gate Disposal Yard, which contains non-aqueous phase TCE and hydrocarbon contamination. Laboratory microcosms with these sediments showed TCE dechlorination at 70oC with measured products of acetylene, ethene, and ethane, indicating an abiotic component of the degradation. In contrast, TCE was dechlorinated to cis-1,2-dichloroethene in experiments at 10oC, likely by biological reductive dechlorination. The observed products at 70oC suggest dechlorination catalyzed by reduced sediment iron. Indications of in situ dechlorination were observed in periodic groundwater samples collected during field-scale electrical resistance heating from an average ambient temperature of about 19oC to near boiling. Dechlorination indicators included an increase in chloride concentration at the onset of heating and observation of acetylene, ethene, and methane at elevated temperatures. The data collected in this study suggest that dechlorination can occur during ERH. The overall cost-effectiveness of ERH may be enhanced by fortuitous in situ dechlorination and, potentially, can be further enhanced by specifically designing and operating ERH to maximize in situ dechlorination.},
doi = {10.1111/j.1745-6592.2007.00141.x},
journal = {Ground Water Monitoring and Remediation, 27(2):96-105},
number = 2,
volume = 27,
place = {United States},
year = {Sun Apr 01 00:00:00 EDT 2007},
month = {Sun Apr 01 00:00:00 EDT 2007}
}