Preliminary tests concerning zero-valent iron efficiency in inorganic pollutants remediation

This study was aimed to a preliminary evaluation of the applicability of granular Zero-Valent Iron (ZVI) to the on site remediation of groundwater polluted by inorganic contaminants by means of a Permeable Reactive Barrier (PRB). A particular interest was devoted to groundwater impacted by Acid Mine Drainage (AMD) that was caused by the oxidation of metal sulphide minerals contained in mine wastes, especially iron disulphide pyrite. Although AMD consequences were particularly evident in surface waters, the percolation through mine wastes may heavily alter the groundwater quality, therefore is particularly important the development of a restrained cost remediation technique for groundwater polluted by AMDs. Approach: In this study the degradation efficiency of Brown size 8/50 ZVI (Peerless Powders and Abrasive Inc., Detroit, US) was evaluated performing a leaching column test and analyzing the Oxidation Reduction Potential (ORP), metals, nitrates, chlorides and sulphates profiles along the column. Results: This test allowed simulating the solid-liquid contact characteristic of a real PRB behavior that proved to be a possible solution for the remediation of inorganic pollutants in groundwater. Conclusion: The considered material showed efficiency above 99% in metals removal, although further tests, involving biotic processes and more reducing conditions, are necessary to improve the degradation of sulphates and nitrates.