TY - JOUR
T1 - Synergistic Zerovalent Iron (Fe0) and Microbiological Trichloroethene and Perchlorate Reductions Are Determined by the Concentration and Speciation of Fe
AU - Rangan, Srivatsan Mohana
AU - Mouti, Aatikah
AU - Lapat-Polasko, Laurie
AU - Lowry, Gregory V.
AU - Krajmalnik-Brown, Rosa
AU - Delgado, Anca G.
N1 - Funding Information:
The authors would like to thank Harry Brenton and Bridget Hoagland from Matrix New World Engineering for their assistance in procuring aquifer materials from PGAN Superfund site. We would like to thank Daniel W. Elliott from Geosyntec Consultants for guidance on selection of Fe products and concentrations tested in microcosms. We would also like to thank Brad Elkins from EOS Remediation LLC for providing SDC-9 culture. This project was supported by Matrix New World Engineering. Partial funding to SMR was also provided by the National Science Foundation (NSF) Engineering Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG) under NSF CA No. EEC-1449501. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect those of the NSF. 0
Publisher Copyright:
© 2020 American Chemical Society.
PY - 2020/11/17
Y1 - 2020/11/17
N2 - Trichloroethene (TCE) and perchlorate (ClO4-) are cocontaminants at multiple Superfund sites. Fe0 is often used during TCE bioremediation with Dehalococcoides mccartyi to establish anoxic conditions in the aquifer. However, the synergy between Fe0 abiotic reactions and microbiological TCE and ClO4- reductions is poorly understood and seldom addressed in the literature. Here, we investigated the effects of Fe0 and its oxidation product, Fe2+, at field-relevant concentrations in promoting microbial TCE and ClO4- reductions. Using semibatch microcosms with a Superfund site soil and groundwater, we showed that the high Fe0 concentration (16.5 g L-1) expected during Fe0 in situ injection mostly yielded TCE abiotic reduction to ethene/ethane. However, such concentrations obscured dechlorination by D. mccartyi, impeded ClO4- reduction, and enhanced SO42- reduction and methanogenesis. Fe2+ at 0.25 g L-1 substantially delayed conversion of TCE to ethene when compared to no-Fe controls. A low concentration of aged-Fe0 synergistically promoted microbiological TCE dechlorination to ethene while achieving complete ClO4- reduction. Collectively, these results illustrate scenarios relevant at or downstream of Fe0 injection zones when Fe0 is used to facilitate microbial dechlorination. Results also underscore the potential detrimental effects of Fe0 and bioaugmentation cultures coinjection for in situ treatment of chlorinated ethenes and ClO4-.
AB - Trichloroethene (TCE) and perchlorate (ClO4-) are cocontaminants at multiple Superfund sites. Fe0 is often used during TCE bioremediation with Dehalococcoides mccartyi to establish anoxic conditions in the aquifer. However, the synergy between Fe0 abiotic reactions and microbiological TCE and ClO4- reductions is poorly understood and seldom addressed in the literature. Here, we investigated the effects of Fe0 and its oxidation product, Fe2+, at field-relevant concentrations in promoting microbial TCE and ClO4- reductions. Using semibatch microcosms with a Superfund site soil and groundwater, we showed that the high Fe0 concentration (16.5 g L-1) expected during Fe0 in situ injection mostly yielded TCE abiotic reduction to ethene/ethane. However, such concentrations obscured dechlorination by D. mccartyi, impeded ClO4- reduction, and enhanced SO42- reduction and methanogenesis. Fe2+ at 0.25 g L-1 substantially delayed conversion of TCE to ethene when compared to no-Fe controls. A low concentration of aged-Fe0 synergistically promoted microbiological TCE dechlorination to ethene while achieving complete ClO4- reduction. Collectively, these results illustrate scenarios relevant at or downstream of Fe0 injection zones when Fe0 is used to facilitate microbial dechlorination. Results also underscore the potential detrimental effects of Fe0 and bioaugmentation cultures coinjection for in situ treatment of chlorinated ethenes and ClO4-.
KW - Dehalococcoides mccartyi
KW - bioremediation
KW - chlorinated ethenes
KW - perchlorate
KW - zerovalent iron (FeZVI)
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U2 - 10.1021/acs.est.0c05052
DO - 10.1021/acs.est.0c05052
M3 - Article
C2 - 33151674
AN - SCOPUS:85096347754
SN - 0013-936X
VL - 54
SP - 14422
EP - 14431
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 22
ER -