Analysis of Flue Gas Desulfurization wastewaters b y Agilent 7700x ICP-MS

Application Note

Authors:
Richard Burrows – TestAmerica Laboratories Inc. USA
Steve Wilbur – Agilent Technologies Inc. USA

The U.S. Environmental Protection Agency (USEPA) is in the process of revising effluent guidelines for the steam electric power generating industry, due to increases in wastewater discharges as a result of Phase 2 of the Clean Air Act amendments. These regulations require SO2 scrubbing for most coal-fired plants resulting in “Flue Gas Desulfurization” (FGD) wastewaters. The revised effluent guidelines will apply to plants “primarily engaged in the generation of electricity for distribution and sale which results primarily from a process utilizing fossil-type fuel (coal, oil or gas) or nuclear fuel in conjunction with a thermal cycle employing the steam water system as a thermodynamic medium. “ [1]. This includes most large scale power plants in the United States. Effluents from these plants, especially coal-fired plants, can contain several hundred to several thousand ppm of calcium, magnesium, manganese, sodium, boron, chloride, nitrate and sulfate. Measurement of low ppb levels of toxic metals (including As, Cd, Cr, Cu, Pb Se, Tl, V and Zn) in this matrix presents a challenge for ICP-MS, due to the very high dissolved solids levels and potential interferences from matrix-based polyatomic ions. Furthermore, FGD wastewater can vary significantly from plant to plant depending on the type and capacity of the boiler and scrubber, the type of FGD process used, and the composition of the coal, limestone and make-up water used. As a result, FGD wastewater represents the most challenging of samples for ICP-MS; it is very high in elements known to cause matrix interferences, and also highly variable. To address this difficult analytical challenge, in 2009 the EPA commissioned the development of a new ICP-MS method specifically for FGD wastewaters. This method was developed and validated at TestAmerica Laboratories Inc. using an Agilent 7700x ICP-MS equipped with an Agilent ISIS-DS discrete sampling system.

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