Traditional and innovative treatment methods for Cr(VI) in soil

There are several treatment technologies available for soils that have elevated levels of chromium. The technologies applicable to a particular chromium site depend on the clean-up goals, the form of the chromium present, and the volume and physical chemical properties of the chromium-containing soils. In many cases the clean-up goals are based on the Cr(VI) concentration in the soils. Therefore, most of the available treatment technologies consist of (I) removing the Cr(VI)-containing soils from the site, (2) immobilizing the chromium so that it will not leach after treatment under field conditions, or (3) reducing the Cr(VI) in the soils to the Cr(lll) state. This article discusses the treatment technologies available for each of these remediation strategies, their advantages and disadvantages, and their relative treatment costs. Technologies evaluated include excavation and offsite disposal, soil washing, soil flushing, electrokinetics, solidificafion/stabilization, vitrification, and chemical and biological reduction. Particular emphasis is given to evaluating the technologies ability to treat soils that have Cr(VI) throughout the soil matrix rather than simply on the surface of the soil particles.