Sulfate-reducing bacteria (SRB) may be used to biologically sufidate reactive zero valent iron surfaces, which may lead to improvements in the rates of the surface-mediated dechlorination of trichloroethene (TCE) and tetrachloroethene (PCE). This work examines the influence of reactive iron particles upon the sulfate reducing bacteria used during sulfidation. Previous work has shown that nanoscale zero valent iron (nZVI) particles may inhibit SRB, but the influence of surface-sulfidated iron, nanoscale or otherwise, on indigenous SRB is unknown. To address this knowledge gap, batch experiments were setup to compare the impact of sulfidated and non-sulfidated ZVI particles (nanoscale and macroscale) on a sulfate reducing culture enriched from contaminated sediments. Results with nZVI show significant enrichment of methanogens when enrichment cultures are exposed to non-sulfidated nZVI particles, presumably due to H<sub>2</sub> production from nZVI. In contrast, microbial communities exposed to sulfidated nZVI showed some loss of diversity and richness but suppressed methanogenic growth. Systems containing sulfidated macroscale ZVI also showed suppression of methanogens but maintained overall richness and diversity. Ongoing transcriptomic studies aim to identify changes in bacterial gene regulation following exposure to particles. Our preliminary data show that biological sulfur amendments, in addition to promoting abiotic dechlorination activity, may minimize changes to indigenous microbial consortia in the subsurface when used as an <i>in situ</i> remediation technology.

Influence of surface-sulfidated iron particles on sulfate-reducing microbial communities

ACS Spring Meeting 2021

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