Comparison of lactate, formate, and propionate as hydrogen donors for the reductive dehalogenation of trichloroethene in a continuous-flow column

Mohammad F. Azizian, Ian P.G. Marshall, Sebastian Behrens, Alfred M. Spormann, Lewis Semprini

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50 Scopus citations


A continuous-flow column study was conducted to analyze the reductive dehalogenation of trichloroethene (TCE) with aquifer material with high content of iron oxides. The column was bioaugmented with the Point Mugu (PM) culture, which is a mixed microbial enrichment culture capable of completely transforming TCE to ethene (ETH). We determined whether lactate, formate, or propionate fermentation resulted in more effective dehalogenation. Reductive dehalogenation, fermentation, and sulfate, Fe(III), and Mn(IV) reduction were all exhibited within the column. Different steady-states of dehalogenation were achieved based on the concentration of substrates added, with effective transformation to ETH obtained when ample electron donor equivalents were provided. Most of the metabolic reducing equivalents were channeled to sulfate, Fe(III), and Mn(IV) reduction. When similar electron reducing equivalents were added, the most effective dehalogenation was achieved with formate, with 14% of the electron equivalents going towards dehalogenation reactions, compared to 6.5% for lactate and 9.6% for propionate. Effective dehalogenation was maintained over 1000 days of column operation. Over 90% of electron equivalents added could be accounted for by the different electron accepting processes in the column, with 50% associated with soluble and precipitated Fe(II) and Mn(II). Bulk Fe(III) and Mn(IV) reduction was rather associated with lactate and propionate addition than formate addition. Sulfate reduction was a competing electron acceptor reaction with all three electron donors. DNA was extracted from solid coupon samples obtained during the course of the experiment and analyzed using 16S rRNA gene clone libraries and quantitative PCR. Lactate and propionate addition resulted in a significant increase in Geobacter, Spirochaetes, and Desulfitobacterium phylotypes relative to "Dehalococcoides" when compared to formate addition. Results from the molecular biological analyses support chemical observations that a greater percentage of the electron donor addition was channeled to Fe(III) reduction when lactate and propionate were added compared to formate, and formate was more effective than lactate in supporting dehalogenation. The results demonstrate the importance of electron donor selection and competing electron acceptor reactions when implementing reductive dehalogenation remediation technologies.

Original languageEnglish (US)
Pages (from-to)77-92
Number of pages16
JournalJournal of Contaminant Hydrology
Issue number1-4
StatePublished - Apr 1 2010

Bibliographical note

Funding Information:
This study was supported through grant R-828772 by the U.S. Environmental Protection Agency-sponsored Western Region Hazardous Substance Research Center and grant ER-1588 by the Strategic Environmental Research and Development Program (SERDP) . Any opinions, findings, conclusions, or recommendations expressed in this material are the opinions of the authors and do not necessarily reflect the views of these organizations. Mention of trade names or commercial products in this paper is solely for the purpose of providing specific information and does not imply recommendation or endorsement by these organizations. We would like to thank Dusty Rose V. Berggren, Ph.D. student for her helpful discussion of the ideas presented in this paper. Appendix A


  • "Dehalococcoides"
  • Clone libraries
  • Continuous-flow column
  • Electron donors
  • Fe(III) reduction
  • Fermentation
  • Mn(IV) reduction
  • Reductive dehalogenation
  • Sulfate reduction


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