Passive bioreactors hold promise for the sequestration of metal(loids) in waters associated with legacy orphaned mining operations. While generally understood to rely on biogenic sulfide evolution to precipitate metals of concern such as zinc and copper, their implementation is more “black box” in nature with limited spatial and temporal biogeochemical insights. To this end, we investigated microbial and geochemical interactions with a focus on the influence of organic substrate, inoculum and resulting microbial ecological selection on metal immobilization and stability in laboratory, pilot, and field scale scenarios. Our results reveal a robust microbial assemblage with respect to time and depth that relies on fermentative syntrophy in support of sulfate reducing bacteria. A combination of synchrotron-based analyses, electron microscopy, x-ray spectroscopy, and geochemical digests further revealed diffuse carbonate and more discrete sulfide-associated precipitation regimes that were largely dictated by inorganic ligand availability rather than localized community structure or diversity profiles.<br/> <br/> <br/>

Biogeochemical investigations of mine water attenuation in lignocellulose-based sulfate reducing bioreactors

253rd National Meeting (2017)

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