Reactive Walls: An Overview

Conventional remediation methods such as pump-and-treat have been used for decades to clean up contaminated sites. However, these technologies have limitations both in terms of cost and cleanup efficiency. Partly in response to perceived shortcomings of conventional remediation technologies and partly for their advantages, a group of alternative remediation technologies called ‘reactive walls’ are under investigation.

In its simplest form, a permeable material is placed in a trench downgradient of the contaminant plume and the contaminant is transported through the soil by the natural hydraulic gradient into the reactive wall where it is modified in some way. Beneficial modification of the groundwater may be achieved by the correct selection of a biological or chemical process in the reactive wall. Possible treatment options include sorption, biodegradation, precipitation, metal-enhanced abiotic dechlorination, oxidation and photoremediation. Because of the range of treatment methods available, reactive walls can be helpful in managing a whole range of contaminants; these include heavy metals, inorganics, chlorinated solvents, hydrocarbons and other organic contaminants.