Arsenic bioremediation by biogenic iron oxides and sulfides

Enoma O. Omoregie, Raoul Marie Couture, Philippe Van Cappellen, Claire L. Corkhill, John M. Charnock, David A. Polya, David Vaughan, Karolien Vanbroekhoven, Jonathan R. Lloyd

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    Abstract

    Microcosms containing sediment from an aquifer in Cambodia with naturally elevated levels of arsenic in the associated groundwater were used to evaluate the effectiveness of microbially mediated production of iron minerals for in situ As remediation. The microcosms were first incubated without amendments for 28 days, and the release of As and other geogenic chemicals from the sediments into the aqueous phase was monitored. Nitrate or a mixture of sulfate and lactate was then added to stimulate biological Fe(II) oxidation or sulfate reduction, respectively. Without treatment, soluble As concentrations reached 3.9±0.9 μMat the end of the 143-day experiment. However, in the nitrate- and sulfate-plus-lactate-amended microcosms, soluble As levels decreased to 0.01 and 0.41±0.13 μM, respectively, by the end of the experiment. Analyses using a range of biogeochemical and mineralogical tools indicated that sorption onto freshly formed hydrous ferric oxide (HFO) and iron sulfide mineral phases are the likely mechanisms for As removal in the respective treatments. Incorporation of the experimental results into a one-dimensional transport-reaction model suggests that, under conditions representative of the Cambodian aquifer, the in situ precipitation of HFO would be effective in bringing groundwater into compliance with the World Health Organization (WHO) provisional guideline value for As (10 ppb or 0.13 μM), although soluble Mn release accompanying microbial Fe(II) oxidation presents a potential health concern. In contrast, production of biogenic iron sulfide minerals would not remediate the groundwater As concentration below the recommended WHO limit. © 2013, American Society for Microbiology.
    Original languageEnglish
    Pages (from-to)4325-4335
    Number of pages10
    JournalApplied and environmental microbiology
    Volume79
    Issue number14
    DOIs
    Publication statusPublished - Jul 2013

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