New Paper: Pilot Scale Injection of nZVI
PGT
Johnson, R. L., J. T. Nurmi, G. O’Brien Johnson, D. Fan, R. O’Brien Johnson, Z. Shi, J. Salter-Blanc Alexandra, P. G. Tratnyek, and G. V. Lowry. 2013. Field-scale transport and transformation of carboxymethylcellulose-stabilized nano zero-valent iron. Environ. Sci. Technol. ASAP (11-Jan-2013).
Laboratory column experiments, deep-bed filtration theory and a radial flow and transport model are used here to examine nano- and micrometer-sized zero-valent iron (ZVI) movement away from an injection well. Column experiments using three highly-mobile ZVI materials and a naturally-occurring aquifer sand indicate that the relationship between pressure drop and specific deposit is in good agreement with literature data for other particle types. Particle transport and pressure data from the column studies yielded filtration parameters that are used as inputs to the flow and transport model to examine filtration and plugging. The model indicates that relatively large volumes of those ZVIs (e.g., kilograms) could be injected before plugging of the formation became problematic (e.g., injection pressure increased by an order of magnitude). However, the model also indicates that injection pressure during radial flow will increase dramatically unless near-well filtration of the particles is kept to a minimum. In addition, even for the best scenario modeled here, the fraction of total injected mass transported greater than 1.5m from the well is very small (~1.5%) and >85% of the mass remains within 1m of the injection point. We conclude that filtration/plugging theory coupled with column studies provides a straightforward method to predict if delivery of ZVI under radial flow conditions will be successful.