Use of the ferrates (FeIV-VI) in combination with hydrogen peroxide for rapid and effective remediation of water--laboratory and pilot study.

In recent years, particles of iron in higher oxidation states (Fe(IV-VI)), commonly called ferrates, have been presented theoretically as very effective oxidants. They can potentially be used for elimination of a wide range of organic and inorganic contaminants. However, so far the majority of applications have been carried out only as laboratory tests using model samples in many cases. The application of ferrates in remediation programs has so far proved to be more complicated with results failing to meet expectations. Therefore there is a necessity to consider the suitability of their use or consider their possible combination with other agents in order to reach required removal efficiencies in remediation. This study is focused on laboratory experiments using industrial groundwater leading to the proposal of a pilot field application realized as an ex-situ remediation. The combination of ferrates with hydrogen peroxide was used in this study in order to enhance the removal efficiency during pilot remediation of groundwater strongly contaminated by a wide range of organic contaminants. This combination has been shown to be very effective. During the 24-hour reaction time the majority of detected contaminants were removed by approximately 60-80%. Moreover, the unpleasant odor of the water was suppressed and suspended particles were removed by the flocculation effect of ferric sludge.

The Application of Nano-Sized Zero-Valent Iron for In Situ Remediation of Chlorinated Ethylenes in Groundwater: A Field Case Study.

In this paper, the authors present the pilot in situ application of nano zero-valent iron (nZVI) for effective remediation of groundwater in an industrial area contaminated by chlorinated ethylenes (CEs), which create a significant group of global environmental contaminants. This work covers the entire 1-year remediation process, including systematic laboratory tests and field application techniques for nZVI. The application was carried out in the area of a metal fabrication industrial facility in the Czech Republic. Contamination of CEs in this area is a consequence of old ecological loads. The entire remediation process contained the following steps: monitoring of the area, selection of the most relevant hot spot, selection of the most appropriate application borehole, systematic laboratory tests, application of nZVI, and postapplication monitoring. Ten kilograms of nZVI were applied as a water suspension into the selected borehole. Significant decreases in concentrations of selected contaminants were observed in the first month after application. The reaction in the borehole was completed within approximately 5 to 6 months after the application and during this period almost 50% elimination of contamination was achieved.