Zero valent iron as an electron-donor for methanogenesis and sulfate reduction in anaerobic sludge

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Abstract

Zero valent iron (ZVI) is a reactive media commonly utilized in permeable reactive barriers (PRBs). Sulfate reducing bacteria are being considered for the immobilization of heavy metals in PRBs. The purpose of this study was to evaluate the potential of ZVI as an electron donor for sulfate reduction in natural mixed anaerobic cultures. The ability of methanogens to utilize ZVI as an electron-donor was also explored since these microorganisms often compete with sulfate reducers for common substrates. Four grades of ZVI of different particle sizes (1.120, 0.149, 0.044, and 0.010 mm diameter) were compared as electron donor in batch bioassays inoculated with anaerobic bioreactor sludge. Methanogenesis was evaluated in mineral media lacking sulfate. Sulfate reduction was evaluated in mineral media containing sulfate and the specific methanogenic inhibitor, 2-bromoethane sulfonate. ZVI contributed to significant increases in methane production and sulfate reduction-compared to endogenous substrate controls. The rates of methane formation or sulfate reduction were positively correlated with the surface area of ZVI. The highest rates of 0.310 mmol CH 4 formed/mol Fe0·day and 0.804 mmol SO 42 reduced/ mol Fe0·day were obtained with the finest grade of ZVI (0.01 mm). The results demonstrate that ZVI is readily utilized as a slow-release electron donor for methanogenesis and sulfate reduction in anaerobic sludge; and therefore, has a promising potential in bioremediation applications.

Original languageEnglish (US)
Pages (from-to)810-819
Number of pages10
JournalBiotechnology and Bioengineering
Volume92
Issue number7
DOIs
Publication statusPublished - Dec 30 2005

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Keywords

  • Anaerobic
  • Bioremediation
  • Elemental iron
  • Elemental metal
  • Fe
  • Metallic iron
  • Permeable reactive barriers

ASJC Scopus subject areas

  • Biotechnology
  • Microbiology

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