Permeable Reactive\nBarrier with Zerovalent Iron Grit\nfor the Remediation of Metal Contaminated Groundwater with High Mineralization:\nA Comprehensive Field Assessment

A large-scale field trial was conducted at a metal-contaminated\nsite to evaluate the effectiveness of a permeable reactive barrier\n(PRB) containing zerovalent iron (ZVI) grit for remediating groundwater\nwith high concentration and mineralization of metals. The work was\nbased on laboratory and field investigations, which indicated that\niron grit was the only economically viable solution. An extensive\nnetwork of monitoring wells was used to observe the site before and\nafter PRB installation, focusing on: (i) metal mass discharge using\npassive mass flux samplers; (ii) impact on microbiota; (iii) metal\ncapture and material characterization with scanning electron microscopy.\nSeven months after the installation of the PRB, the average mass fluxes\nof Zn, Pb, and Ni in the outflow decreased by 82%, 72%, and 79%, respectively,\ncompared to concentrations before the installation. The average Mn\nmass flux increased by approximately 67% due to the dissolution of\nMn oxides, and gradually declined over time following the PRB installation.\nThe treatment did not cause any apparent harmful side effects on the\npresent microbiota. Results indicate this setup might also be appropriate\nfor other locations dealing with high groundwater mineralization,\nthough the Mn leaching should be further investigated.