Effect of Nanoscale Zero-Valent Iron Treatment on Biological Reductive Dechlorination: A Review of Current Understanding and Research Needs
Critical reviews in environmental science and technology
Nanoscale zero-valent iron (nZVI) is a strong non-specific reducing agent that is used for in situ degradation of chlorinated solvents and other oxidized pollutants. However, there are significant concerns regarding risks posed by the deliberate release of engineered nanomaterials 20 into the environment, which have triggered moratoria, for example, in the United Kingdom. This critical review focuses on the effect of nZVI injection on subsurface microbial communities, which are of concern due
... re of concern due to their important role in contaminant attenuation processes. Corrosion of ZVI stimulates dehalorespiring bacteria, due to the production of H 2 that can serve as an electron donor for reduction of chlorinated contaminants. Conversely, lab studies show 25 that nZVI can be inhibitory to pure bacterial cultures, although toxicity is reduced when nZVI is coated with polyelectrolytes or natural organic matter. The emerging toolkit of molecular biological analyses should enable a more sophisticated assessment of combined nZVI/biostimulation or bioaugmentation approaches. While further research on the consequences of its application for subsurface microbial communities is needed, nZVI continues 30 to hold promise as an innovative technology for in situ remediation of pollutants. It is particularly attractive for the remediation of subsurface environments containing chlorinated ethenes because of its ability to potentially elicit and sustain both physical-chemical and biological removal despite its documented antimicrobial properties.