Solidification/Stabilization Technologies for the Prevention of Surface and Ground Water Pollution from Hazardous Wastes

Abstract

Solidification/stabilization treatment processes immobilize hazardous constituents in the waste by changing these constituents into immobile (insoluble) forms, binding them in an immobile matrix, and/or binding them in a matrix which minimizes the material surface exposed to weathering and leaching. Solidification/stabilization treatment processes can include aluminum silicate and cement-based fixation, pozzolanic-based fixation, or vitrification.

The process of solidification/stabilization is a widely accepted treatment/disposal process for a broad range of wastes, particularly those classified as toxic or hazardous, which are not suited for normal methods of disposal and where special treatment is necessitated. Portland cement is a material found to be most useful for solidification/stabilization purposes due to its ability for heavy metals fixation and immobilization. For the immobilization of waste containing high concentrations of heavy metals, as in the case of the galvanization process, solidification is a very acceptable treatment. This is also consistent with the recent EU directions, which refereed to the solid waste management. Solidification/stabilization processes will play a more important role since, in the near future, only inert or stabilized wastes should be landfilled. Solidification/stabilization process means binding the hazardous material in the hydraulic binders for safe landfilling or use in civil engineering purposes. Various types of cement and pozzolanas (e.g., coal burning fly ash, lime, blast-furnace slag and similar materials) are mostly used as the stabilizing matrix. Those stabilization techniques are used for the immobilization of inorganic or organic waste. The end product of the treatment, usually after sufficient curing, is solid monolithic material which, depending on characteristics of leaching, can be usefully applied or disposed of in a safe way.