Designing laboratory metallic iron columns for better result comparability
Résumé
Despite the amount of data available on investigating the process of aqueous contaminant removal by metallic iron (Fe0), there is still a significant amount of uncertainty surrounding the design of Fe0 beds for laboratory testing to determine the suitability of Fe0 materials for field applications. Available data were obtained under various operating conditions (column characteristics, Fe0 characteristics, contaminant characteristics, oxygen availability, solution pH) and are hardly comparable to each other. The volumetric expansive nature of iron corrosion has been univocally reported as major drawback for Fe0 beds. Mixing Fe0 with inert materials has been discussed as an efficient tool to improve sustainability of Fe0 beds. This paper discusses some problems associated with the design of Fe0 beds and proposes a general approach for the characterization of Fe0 beds. Each Fe0 column should be characterized by its initial porosity, the composition of the steady phase and the volumetric proportion of individual materials. Used materials should be characterized by their density, porosity, and particle size. This work has introduced simple and reliable mathematical equations for column design, which include the normalisation of raw experimental data prior to any data treatment.