APPLICATION OF NANOSCALE ZERO-VALENT IRON FOR GROUNDWATER REMEDIATION: LABORATORY AND PILOT EXPERIMENTS

It is known that the reductive effects of zero-valent iron (Fe⁰) and the sorptive capability of iron and its oxides can be used for both the dehalogenation of chlorinated hydrocarbons (CHC), especially of chlorinated ethenes (PCE → TCE → DCE → VC → ethene, ethane), and the removing of heavy metals from groundwater by turning them into a less-soluble form through changes of their oxidation state, or by adsorption. These consequences are being exploited in the construction of iron filling permeable reactive barriers for a longer time.¹ The advantages of nanoscale zero-valent iron (nanoFe⁰) over the macroscopic one consist not only in the better reactivity implicit in their greater specific surface area but also in their mobility in rock environment.^2,3 Numerous laboratory experiments, especially the batch-agitated experiments, with samples from seven various contaminated localities in Europe have been carried out with the aim to discover the measurement of the reductive effect of the nanoFe⁰ on selected contaminants. It was found that the nanoFe⁰ can be reliably usable as a reductive reactant for in-situ chemical decontamination of sites polluted by chlorinated ethenes (CEs), or hexa-valent chromium (Cr^VI). The rate of reductive reaction and the optimal concentrations for the real remediation action were determined. On the basis of these laboratory experiments, the methods for pilot application of nanoFe⁰ have been specified. Subsequently the pilot experiments were accomplished in surveyed localities.