(145e) Microbial Interactions with Nanoscale Zero Valent Iron: Environmental Applications and Implications

Nanoscale zero valent iron particles (NZVI) are a promising technology for in situ remediation of chlorinated solvent contaminated groundwater. Treatment requires large amounts of nanomaterials (in g/L concentrations) to be injected into the aquifer. This raises concerns over the potential impact of these reactive nanomaterials in the environment and motivates an assessment of how NZVI injection may alter ecosystems. Microbial communities are an integral part of aquifer ecosystems, driving chlorinated solvent natural attenuation or heavy metal immobilization processes as well as nutrient cycling. This microcosm study demonstrates the microbiological and geochemical impact of NZVI injection on TCE contaminated aquifer material. NZVI creates reducing conditions and generates cathodic hydrogen, stimulating microbial sulfate reduction and methanogenesis. NZVI does not decrease total bacterial abundance, but it significantly changes the microbial community composition. These changes appear to be caused primarily by the changes in geochemical conditions. Biodegradable polyaspartate coatings on NZVI increase Eubacterial populations by an order of magnitude. Combined, these results have positive implications for coupling NZVI treatment with bioaugmentation with dechlorinating microorganisms for chlorinated solvent remediation. Additional studies are underway to discover whether or not synergism can be achieved between the two treatment methods.