Metal-Contaminated Soils: Remediation Practices and Treatment Technologies

Abstract

Heavy metals have polluted many sites in industrial countries and pose risks for ecological systems. In the United States, metals are present at about three-quarters of Superfund and Department of Defense sites. Further, there are relatively few soil treatment projects that have treated metals compared to organic contaminants. The enormous quantity and the complexity of metal-contaminated soils (MCS) constitute an important challenge for their remediation. This paper provides: (1) a summary of the remedial options and treatment technologies for MCS; and (2) a review of the field applications of the treatment technologies performed in the United States over the past 25 years. The discussion focuses on the alternatives to ex situ solidification/stabilization (S/S) through a review of 128 case studies. Additionally, a comparison of the practices used in Europe and in the United States relating to the treatment of MCS is also presented. Soil washing, phytoremediation, electrokinetics and, in situ stabilization techniques provide an effective alternative to conventional S/S and disposal options. Further research is needed to improve understanding of the phytoremediation and in situ metal stabilization processes.