Title

Biostimualtion and bioaugmentation to enhance reductive dechlorination of TCE in a long term flow through column study

Document Type

Article

Journal/Book Title/Conference

Ground Water Monitor

Volume

35

Issue

10693629

Publisher

Blackwell Publishing Ltd

Publication Date

5-7-2015

First Page

76

Last Page

88

DOI

10.1111/gwmr.12113

Abstract

Large laboratory columns (15.2 cm diameter, 183 cm long) were fed with groundwater containing trichloroethylene (TCE), were biostimulated and bioaugmented, and were monitored for over 7.5 years. The objective of the study was to observe how the selection of the carbon and energy source, i.e., whey, Newman Zone® standard surfactant emulsified oil and Newman Zone nonionic surfactant emulsified oil, affected the rate and extent of dechlorination. Column effluent was monitored for TCE and its degradation products, redox indicators (nitrate-N, Fe(II), sulfate), and changes in iron mineralogy. Total bacteria and Dehalococcoides mccartyi strains were quantified using q-PCR. Complete dechlorination was only observed in the whey treated columns, occurring 1 year after bioaugmentation with addition of a culture known to dechlorinate TCE to ethene, and 3 years later in the non-bioaugmented column. The addition of the emulsified oils with or without bioaugmentation resulted in dechlorination only through cis-DCE and vinyl chloride. While Dehalococcoides mccartyi strains are the only known bacteria that can fully dechlorinate TCE, their presence, either natural or augmented, was not the sole determiner of complete dechlorination. The establishment of a supporting microbial community and biogeochemistry that developed with continuous feeding of whey, in addition to the presence of D. mccartyi, were necessary to support complete reductive dechlorination. Results confirm that careful selection of a biostimulant is critical to the success of TCE dechlorination in complex soil environments. © 2015, National Ground Water Association.

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