Emissions measurement and metals processing in smokes. The case of cadmium, mercury and lead - State-of-the-art

Energy consumption and industrial production have increased throughout the 20. century and have given rise to enormous problems of environmental pollution, especially by heavy metals (mercury, lead, cadmium etc...). The presence of many forms of these elements of anthropic origin in different compartments of ecosystems (water, the sediments, soils and the atmosphere), at toxic levels, illustrates the consequences of improperly managed metallic emissions. Heavy metals are characterized by their persistence, their toxicity, and their accumulation capacity in the environment. Their release into the air can cause an environmental hazard in the long term. Furthermore, they can be transported through the air over long distances and deposited far from the initial source. The pollutants considered responsible for toxic environmental hazard by order of importance are: mercury, cadmium and lead in this state of the art. Mercury is considered as a major pollutant due to its transportation over long distances, its bio transformation into toxic methylated compounds and its bioaccumulation in the trophic chain. Cadmium is considered as the most toxic metal but is relatively rare and is mainly found in metal ores. Its accumulation in sediments and remobilization capacity constitute the most important hazards. Although less toxic than mercury and cadmium, lead is more abundant in natural forms in the environment and is used in great quantities in industry, which makes it a permanent hazard to health. This state of the art was elaborated in four distinct parts: - the first part sets an inventory of the origins of heavy metals (Cd,Hg, Pb), the last emission amounts of these metals in the atmosphere and the results of the recent epidemiological studies concerning the noxious effects of these three metals on the human health and the environment. - the second part is an inventory of the different norms relating to the three heavy metals studied. - the third part concerns the metrology of heavy metals (Cd, Hg, Pb), it is composed of an inventory of the measurement techniques presently used to detect these metals and their compounds in the air. - the last part presents the different industrial sectors which emit heavy metals(Cd, Hg, Pb) and presents the different processes presently available for removing these heavy metals from the gaseous effluents. (author)