The cement industry as a scavenger in industrial ecology and the management of hazardous substances

The cement industry uses a variety of secondary materials and fuels, thus fulfilling the role of scavenger in industrial ecology (IE). The use of wastes in cement production has been advocated to reduce cement production costs and to achieve the degradation and immobilization of hazardous compounds. In dealing with hazardous elements contained in the wastes, this development has side effects such as relatively significant stack emissions of heavy metals and leaching of hazardous compounds during the life cycle of cement-derived products. Emissions and leaching potential may be substantially lowered by reducing levels of hazardous elements in wastes before they are included in cement production and by selectively capturing mercury from stack gases. An analogy to metabolic functions of selective uptake, sequestration, and selective excretion is presented.