COUPLING THERMAL TREATMENT AND MICROBIAL REDUCTIVE DECHLORINATION FOR THE ENHANCED REMEDIATION OF CHLORINATED ETHENES
targeted, synergistic implementation of in situ thermal treatment (ISTT) with microbial
reductive dechlorination (MRD) has potential to enhance biodegradation of
tetrachloroethene (PCE), trichloroethene (TCE), and their chlorinated daughter products,
while reducing remedial costs and cleanup time relative to conventional in situ
remediation technologies. Growth rates and activity ... read moreof reductively dechlorinating
bacteria have been shown to increase during or following field-scale ISTT, but the
causal mechanisms are poorly understood. Two of the most likely mechanisms were
investigated: 1) increased availability of bioavailable substrates in the aqueous phase
and 2) direct temperature stimulation of the microbial community. Through a series of
laboratory-scale batch reactor and 1-D column studies, electron donors and fermentable
precursors released from porous media during thermal treatment were identified,
quantified, and evaluated for their ability to promote the complete microbial reductive
dechlorination of PCE to non-toxic ethene. Column studies were also completed to
elucidate the impacts of temperature on the growth and activity of a dechlorinating
consortium under continuous flow conditions. Results indicate that compounds released
from soil organic matter during thermal treatment can represent a substantial source of
bioavailable reducing equivalents, capable of sustaining bacterial ethene formation even
in the absence of an external electron donor source. Sustained ethene formation was also
demonstrated at elevated temperatures previously believed to inactivate key reductively
dechlorinating bacteria. Collectively, results reaffirm the argument for the coupled
implementation of ISTT and microbial reductive dechlorination technologies, and
underscore the potential to improve contaminant degradation
Thesis (Ph.D.)--Tufts University, 2018.
Submitted to the Dept. of Civil Engineering.
Advisors: Natalie Capiro, and Kurt Pennell.
Committee: Frank Loffler, and Ayse Asatekin.
Keyword: Environmental engineering.read less