Microbial characterization of groundwater undergoing treatment with a permeable reactive iron barrier

Marcio L.B. Da Silva, Richard L. Johnson, Pedro J.J. Alvarez

Research output: Contribution to journalArticle

21 Scopus citations

Abstract

Phylogenetic analyses of micro-organisms in groundwater samples from within and around a zero-valent iron (ZVI) permeable reactive barrier (PRB) identified several bacteria that could utilize H2 produced during anaerobic ZVI corrosion and residual guar biopolymer used during PRB installation. Some of these bacteria are likely contributing to the removal of some groundwater constituents (i.e., sulfate). Bacteria concentrations increased from ∼101 cells mL-1 at 2 m upgradient to ∼10 2 cells mL-1 within the PRB and ∼104 cells mL-1 at 2 to 6 m downgradient. This trend possibly reflects increased substrate availability through the PRB, although a corrosion-induced increase in pH beyond optimum levels within the iron layer (from pH 7 to 9.8) may have limited microbial colonization. Micro-organisms that were detected using quantitative PCR include (iron reducing) Geobacter sp. (putative methanogenic) Archaea, and (sulfate reducing) δ-proteobacteria such as Desulfuromonadales sp. Sequencing of DGGE bands also revealed the presence of uncultured dissimilatory metal reducers and Clostridia sp., which was dominant in a sample collected within the ZVI-PRB. These results suggest that indigenous microbial communities are likely to experience population shifts when ZVI-PRBs are installed to exploit several metabolic niches that evolve when ZVI corrodes. Whether such population shifts enhance ZVI-PRB performance requires further investigation.

Original languageEnglish (US)
Pages (from-to)1122-1127
Number of pages6
JournalEnvironmental Engineering Science
Volume24
Issue number8
DOIs
StatePublished - Oct 1 2007

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Keywords

  • Groundwater samples
  • Permeable reactive barrier
  • Phylogenetic analyses
  • Zero-valent iron

ASJC Scopus subject areas

  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution

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