Permeable Reactive Barriers for Heavy Metal Removal

Abstract

Heavy metal contamination of groundwater is a worldwide problem. Landfill leachate and acid mine drainage are possible sources for groundwater contamination by heavy metals. Heavy metals from groundwater can enter the food chain through bio-accumulation and bio-magnification, posing a threat to all forms of life. A permeable reactive barrier is one of the technologies employed for remediation of heavy metal contaminated groundwater. The concept of a permeable reactive barrier involves the emplacement of a permeable barrier containing reactive materials across the flow path of the heavy metal contaminated groundwater to intercept and treat the heavy metals as the plume flows through it under the influence of the natural hydraulic gradient. Site selection and selection of reactive media, as well as construction and operation, are some of the challenges faced in the application of permeable reactive barriers. A variety of inorganic and organic reactive media are employed in a permeable reactive barrier to remove the heavy metals. Heavy metal removal is accomplished through processes such as adsorption, precipitation and biodegradation. In this chapter, various aspects of treating heavy metal groundwater contamination using the permeable reactive barrier technology have been reviewed. The major topics include: (1) causes of heavy metal contamination in groundwater, (2) types of reactive media used in a permeable reactive barrier, (3) criteria for selection of reactive media, (4) mechanisms for removal of heavy metals by reactive media, and (5) comparison of performance of various reactive media.