| OCR Text |
Show trace metals were reported in ppmw of the fuel. The only exceptions were the ftlm plastics and RL&HP streams, where low temperature ashing was required prior to sample digestion. Results were reported as ppmw of the dry fuel rather than the ash, however. Mean, minimum, and maximum values were obtained for each parameter in the proximate and ultimate analysis, and in the trace metal composition. Following analysis of the light fraction or RDF, the "grits" were analyzed. The "grits" analysis was performed in a manner analogous to the paper streams of the RDF, as the material was digested directly in order to determine trace metals content. Again, four samples were employed for each parameter (e.g. carbon content, higher heating value, chromium content). Methodology for Addressing Metals Speciation The nature of WDOE regulations requires addressing metals speciation as well as total metals concentration. This task can be performed analytically for chromium. For all of the other IARC compounds, however, metal speciation can only be addressed by computer modeling and related thermodynamic analyses because analytical techniques do not exist to measure speciation at the levels required by WDOE regulations. In order to document this fact, Ebasco Environmental surveyed the following laboratories: Hazen Research; AmTest; Advanced Combustion Engineering Research Center, University of Utah; Fuels Engineering Department, University of Utah; Energy and Environmental Research Center, University of North Dakota; Analytical Technologies; and Northwest Environmental Laboratory. Each laboratory and research group cited the impossibility of measuring specific metal species at detection levels below 100 ppmw. Even advanced techniques such as ESCA (Electron Spectroscopy for Chemical Analysis) and NAA (Neutron Activation Analysis) were considered insufficient for the task at hand (Masset, 1990). Regulators had entered an arena in which measurement could not be conducted. Indirect methods of approximation were required. In order to address speciation, then, the IARC metals were divided into two groups: those that required a literature review and those that could be analyzed by computer modeling. Those metals where speciation was best addressed by literature review included arsenic, cadmium, and chromium; those addressed by computer modeling included barium, beryllium, lead, nickel, strontium, and zinc. The literature review examined theoretical work with respect to arsenic and cadmium (see, for example, Behrens and Mason, 1981; Kazenas et. al., 1984; Schuffenecker et. al., 1981), and empirical research with respect to chromium (see, for example, Stumbar et. al., 1989; Butler, Knoll, and Midgett, 1986). The metal speciation analysis based upon computer modeling employed the Gordon-McBride thermodynamic model commonly utilized to calculate products of combustion at equilibrium (S. Gordon et. al., 1971; Gordon and McBride, 1976). This model has been employed previously for analyzing the fate of trace metals in a wide variety of combustion and incineration settings (Barton et. al., 1988; Barton et. al., 1989; Brittain et. al., 1988; Seeker et. al ., 1987); and it has been used to indicate not only the -5- |
