Permeable Reactive Barriers with Zero-Valent Iron and Pumice for Remediation of Groundwater Contaminated with Multiple Heavy Metals

In this study, we present an optimized method for remediating multiple metals and metalloids using pumice permeable reactive barrier with zero-valent iron (ZVI) and with a modified reactor packing bed. The objective was to determine the effect of the contaminant breakthrough capacity of the modified bed, volumetric discharge of treated water, and the reactive material. Arsenic, manganese, iron, and zinc species with the initial concentrations of 0.001, 275.31, 0.61, and 0.063 mmol/L were used as the reference contaminants, respectively. ZVI and pumice were studied to remove the contaminants from synthetic groundwater. Contaminant breakthrough capacity (removal efficiency of 1) was not observed in the ZVI reactor bed with pumice for the 90-day period. The application of irregular reactive bed packing enhanced gas and water transport and removal of heavy metal(loid) for ZVI and pumice column reactor. Although contaminant breakthrough capacity (removal efficiency of 1) was not observed in the ZVI column reactor, clogging phenomena was characteristic. The column with only pumice exhibited zinc and manganese breakthrough capacity after 8 days owing to poor adsorption characteristics because the dominant remediation mechanism was cation exchange. Reactive material characteristics, and the remediation mechanism and for each reactive system, are described in this study. This study showed that the asymmetrical bed geometry could aid in the remediation process and venting of gas buildup.