| The proportion of coal consumption in my country is maintained at a very high level.The massive use of coal resources will cause harm to the environment.Trace elements such as Hg,As,Se,Pb,Cd,and Cr pose a high threat to the environment and the human body.As one of the main emission sources of trace element pollution,coal-fired power plants will also remove trace elements in the flue gas when using advanced pollutant control devices to remove pollutants.Trace elements such as mercury will also be removed.There are relatively few studies on the migration and enrichment of elements in the wet flue gas desulfurization system.In this paper,a typical domestic ultra-low emission coal-fired power plant is selected as the research object to analyze the six types of mercury in the wet flue gas desulfurization system.The distribution ratio of trace elements,migration and enrichment and ecological environment pollution assessment have been studied systematically.The solid-liquid-gas-phase samples of the wet flue gas desulfurization system of the power plant were sampled,detected and analyzed,and the distribution and migration laws of trace elements such as mercury in the system were analyzed through the improved trace element material balance calculation method.The five elements of Se,Pb,Cr and Cd have different levels of removal effects,but As is re-released.The content of trace elements such as mercury in the desulfurization wastewater sludge is much higher than that in the desulfurization gypsum.Desulfurization wastewater treatment system The removal efficiency of Hg,As.Se,Pb,Cd and Cr elements reached 79.2%,50.3%,50.5%,57.4%,34.4%and 59.7%respectively;the desulfurization wastewater treatment process has a certain enrichment of Hg and Se The effect is not obvious on the enrichment effect of As.Pb and Cr elements,and it does not play an enrichment effect on Cd.The element migrates and enriches into the solution in the form of occurrence with higher solubility in the way of internal circulation;The study on the occurrence of typical solid phase by-products of the desulfurization system by the advanced extraction method found that the solubility of Cd in wastewater sludge is relatively high,and other trace elements mainly exist in the form of residues.The environmental stability of trace elements ranges from large to The order is Cd>Se>Cr>Pb>As,and the environmental stability of gypsum is slightly better than that of sludge.The high concentration of trace elements enriched in the reflux water is mainly caused by the fine particles that are not easy toform gypsum in the desulfurization slurry and the gypsum dehydration filtrate.The stacking of by-products of coal-fired power plants will cause ecological environmental pollution.This article selects three methods to conduct ecological potential risk assessment and risk characteristic index analysis.The research shows that the assessment of potential ecological hazard index method found that gypsum constitutes a slight ecological hazard,the main performance is For medium-risk Hg pollution,sludge constitutes a strong degree of ecological hazard risk.Its index is as high as 876.87,which is represented by high-risk Hg pollution and medium-risk Cd pollution.Take a comprehensive look at the byproducts of these two desulfurization systems before they enter the soil environment.It is extremely necessary to carry out the corresponding trace element disposal. |
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