Edinburgh Napier University

  A novel remediation strategy, the zero-valent iron fracture reactive barrier (Fe0 FRB), is proposed to clean up chlorinated solvent pollution of groundwater in a fractured aquifer. A Fe0 FRB is an extended reactive zone where the fractures are partly filled with iron. It can be created by injecting a viscous, biodegradable gel suspended with iron particles into selected fractures via boreholes. To aid in the design and performance assessment of such complex systems, an approach has been developed for an idealised, single, partly iron-filled fracture wherein the physical and chemical processes are represented by a first-order lumped rate parameter. The lumped model was validated against a laboratory fracture experiment. A numerical model coupled with the lumped rate parameter model was also used for the performance assessment of an Fe0 FRB in a hypothetical chalk aquifer. The performance assessment of the chalk aquifer suggests that Fe0 FRB could be used to treat groundwater contaminated with chlorinated solvents. High treatment efficiency of the FRB can be achieved by employing highly reactive nanoscale iron or by using a high proportion of microscale iron fill and fracture enlargement. The modelling assessment also provides some preliminary conclusions on the optimal design of a Fe0 FRB, such as the proportion of iron fill, the size of the FRB, the amount of fracture enlargement, etc.