Introduction
Industrial activities in the United States and other developed countries generate large volumes of by-products wastes. These by-products must be properly disposed in order to avoid threats to both the environment and public health. Waste immobilization techniques are the recent technologies proposed to prevent the free movement of contaminants in waste and surrounding media. Immobilization can be temporary as in containment or almost permanent as in the case of vitrification. To select an effective immobilization technique, some basic characteristics of wastes must be evaluated. Table 1 presents common types of contaminated wastes and current treatment methods. Some parameters for their classifications are types ~urban, industrial, radioactive wastes!; form ~solid, liquid, semisolid!; size ~small, medium, large areas!; locations ~urban, rural!; contaminant concentration.
In addition, many wastes, when mixed with other wastes or other materials, can produce effects that are harmful to human health and the environment USEPA ~1991!, such as
• Heat or pressure,
• Fire or explosion,
• Violent chemical reaction,
• Toxic dust, fumes or gases, and
• Flammable fumes or gases.
All the above factors should be considered in selecting a proper immobilization technique. Immobilization techniques can be broadly categorized into containment, solidification, and vitrification.