Waste immobilization technologies

Waste immobilization techniques prevent the free movement of contaminants in waste. Three major types of immobilization techniques, namely, the temporary containment techniques, cost effective solidification/stabilization techniques, and permanent vitrification techniques are described. The purpose of this paper is to provide a comprehensive list of waste immobilization techniques with sufficient descriptions including advantages, disadvantages, and limitations. The selection of an appropriate waste immobilization technique depends on site conditions and type and amount of waste. Several temporary containment techniques such as pumping, capping, draining, and slurry walls are discussed, solidification/stabilization techniques can be either chemical or nonchemical. Chemical methods are very popular and cost effective. Contaminated soils can be effectively solidified and stabilized using chemical methods, but the resulting products may not always be reused as construction materials or consumable materials. Vitrification is an innovative technology that incorporates hazardous and contaminated waste into a chemically, durable glass-like product. Vitrification can be either in situ or ex situ. The containment techniques are usually used to "buy time" under emergency or temporary conditions. Contaminated soils can be effectively solidified and stabilized using chemical methods, but the resulting products may not always be reused as construction materials or consumable materials. The Environmental Protection Agency has declared vitrification to be the "best demonstrated available technology" for heavy metals and high-level radioactive waste.