Mercury emissions power plant

Although the petrochemical and metals industries were the primai y focus of the toxic air pollutants legislation, approximately forty of these substances have been detected in fossil power plant flue gas. Mercury, which is found in trace amounts in fossil fuels such as coal and oil, is liberated during the combustion process and these emissions may be regulated in the future. EPA issued an Information Collection Request (ICR) that required all coal-fired plants to analyze their feed coal for mercury and chlorine. Since these data will be used in making a regulatory decision on mercury near the end ot the year 2000, it is critical that the power industry provide the most accurate data possible. 

Reductions in U.S. mercuiy emissions from medical and municipal waste incinerators and other industrial sectors have already occurred. Additional emission reductions from some coal-fired power plants have also already begun as co-benefits from technologies used to control SO2 and NO emissions. These mercury emissions from power plants are, however, expected to be reduced further over the next few decades. Meanwhile, changes in mercuiy emissions in other parts of the world may also affect some U.S. ecosystems. 

Chu, P and D.B. Porcella. 1995. Mercury stack emissions from U.S. electric utility power plants. Water Air Soil Pollut. 80 135-144. 

Methylmercury, which we referred to in the neurotoxicity section, occurs in fish and shellfish found in both the ocean and fresh water systems. The mercury that is the source of methylmercury arises from power plant emissions and industrial processes. Some even comes from... 

Mercury is one of a number of toxic heavy metals that occur in trace amounts in fossil fuels, particularly coal, and are also present in waste materials. During the combustion of fuels or wastes in power plants and utility boilers, these metals can be released to the atmosphere unless remedial action is taken. Emissions from municipal waste incinerators can substantially add to the environmental audit of heavy metals, since domestic and industrial waste often contains many sources of heavy metals. Mercury vapor is particularly difficult to capture from combustion gas streams due to its volatility. Some processes under study for the removal of mercury from flue gas streams are based upon the injection of finely ground activated carbon. The efficiency of mercury sorption depends upon the mercury speciation and the gas temperature. The capture of elemental mercury can be enhanced by impregnating the activated carbon with sulfur, with the formation of less volatile mercuric sulfide [37] this technique has been applied to the removal of mercury from natural gas streams. One of the principal difficulties in removing Hg from flue gas streams is that the extent of adsorption is very low at the temperatures typically encountered, and it is often impractical to consider cooling these large volumes of gas. 

Appreciable interest has been generated in the use of activated carbons for flue gas cleanup, especially for the removal of SOx and NO the adsorption of mercury from flue gases was discussed earlier. From the environmental point of view, emissions from the combustion of fossil fuels in power plants and similar industrial processes are major contributors to a lowering of air quality. The flue ga.ses carry traces of SOi and NO, which can be oxidized and converted to their acid forms in the presence of atmospheric water vapor, and they may also combine with other volatile organics to form ozone and smog. Similarly, low level SOj and NOx emissions from automobiles, while insignificant for individual vehicles, become a large source of pollution when multiplied by the millions of vehicles that are on the roads. 

Charnley G. Assessing and managing methylmercury risks associated with power plant mercury emissions in the United States. MedGenMed 2006 9(8) 64. 

If this development continues, there is little doubt that more regional problems will appear. Incidents of "red tide" are reported from the North Sea area. This is an over-growth of toxic algae which follows excessive deposition of nitrates by precipitation and kills the fish. Watersoluble mercury compounds in the atmosphere, partly due to emissions from coal-fired power plants and partly due to an oxidation of the natural mercury vapour, have resulted in a serious contamination of freshwater fish in Scandinavia. Already fish from many lakes cannot be marketed in Sweden, because the mercury content exceeds 1 mg/kg. 

In many previous chapters, the discussion of questions regarding various environmental aspects of environmental chemistry in air, water, and soil compartments touched upon the problems of heavy metals. However, we should pay more attention to these pollutants, which are of crucial environmental concern in the Asian region. In this chapter, the emphasis will be given to heavy metal emissions from coal (including lignite) burning power plants, and to the specific aspects of environmental behavior of the most dangerous contaminants, like arsenic, mercury and lead. The problems of heavy metal site remediation will be considered in Chapter 16. 

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