A critical review of stabilization/solidification technology

The processes and techniques of stabilization/solidification (S/S) have matured into an accepted, and important, part of environmental technology. As a result, a great many S/S methods have been promoted recently and offered for the treatment of hazardous and other wastes from industry, municipalities, and government sources. The purpose of this article is review these methods critically in light of the current regulatory atmosphere that controls and often mandates their use. An overview of the technology is provided. The generic and proprietary S/S processes (chemical processes, physical processes, and thermal processes) are described. Of these, six generic chemical processes dominate the field and encompass nearly all of the treatment work and proprietary products to date: Portland cement, cement/flyash, cement/soluble silicate, lime/flyash, kiln dust, and phosphate. Current and anticipated major waste streams using S/S technology today are summarized. The S/S approach for each of these are reviewed. For metals, the primary factors affecting immobilization are pH control, chemical speciation, and redox potential control. For organics, immobilization of constituents can be broken down into two primary classifications: reactions that destroy or alter organic compounds, and physical processes such as adsorption and encapsulation.