Environmental Life Cycle Assessment of Permeable Reactive Barriers: Effects of Construction Methods, Reactive Materials and Groundwater Constituents

The effects of the construction methods, materials of reactive media and groundwater constituents on the environmental impacts of a permeable reactive barrier (PRB) were evaluated using life cycle assessment (LCA). The PRB is assumed to be installed at a simulated site contaminated by either Cr(VI) alone or Cr(VI) and As(V). Results show that the trench-based construction method can reduce the environmental impacts of the remediation remarkably compared to the caisson-based method due to less construction material consumption by the funnel. Compared to using the zerovalent iron (Fe⁰) and quartz sand mixture, the use of the Fe⁰ and iron oxide-coated sand (IOCS) mixture can reduce the environmental impacts. In the presence of natural organic matter (NOM) in groundwater, the environmental impacts generated by the reactive media were significantly increased because of the higher usage of Fe⁰. The environmental impacts are lower by using the Fe⁰ and IOCS mixture in the groundwater with NOM, compared with using the Fe⁰ and quartz sand mixture. Since IOCS can enhance the removal efficiency of Cr(VI) and As(V), the usage of the Fe⁰ can be reduced, which in turn reduces the impacts induced by the reactive media.