Chemical and toxicological properties of coal fly ash - University of ...

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Figure 26. Changes in the concentrations of selected aqueous constituents in the LTE extract of fly ash W2 with time.In each solution, most of the constituents were in greater concentrationsduring the first week of extraction than they were later. Beginning almostirrmediately after the first day, these same constituents decreased inconcentration, and this trend prevailed for about 60 to 120 days. Afterthat interval, the concentrations of these constituents no longer changedsignificantly, having reached relatively steady state conditions.In both the initially acidic solutions (I2 and 17) the concentrations of B,Ba, Ca, Cd, Mg, Mn, Na, Ni, Si, S04, and Zn as well as pH becameconstant in 3 to 5 weeks (Tables 14, 16). The dominant factor controllingthe solubility of inany metals is pH. Both acidic extracts became neutralin pH and, as a consequence, several constituents were less soluble in theresulting nonacidic solution. Therefore, Al, Be, Cd, Cr, Cu, Fe, and Niwere in greater concentrations during the early phase of the extractions.Molybdenum steadily increased during the entire extraction interval of theacidic fly ashes and had not reached a steady state when the LTEs wereterminated.These changes in solubility over time make generalized solubility trendsdifficult to predict with certainty. For example, the ranking of theamount in solution versus the total amount in the solid for fly ash I2after 24 hours of extraction was Cd, Zn > S04-S > B > Ca, Mg > Cu > Na,Be, Ni, K > Mn > Cr > A1 > Ba, Si, Mo, Pb, and Fe. After 142 days, therelative solubilities were: S04-S > B > Mg > Mo, Ca > Cd > Na > Se > Mn> Zn > Sb, K > Ni > Ba > Cu, Cr, Pb, and Si. The change in solubility
trends is a reflection of the shifts in equilibria controlling thesolubility of the constituents during the extraction interval.In contrast, the pH of the two alkaline solutions (I3 and 18) remainedabove pH 10 during the entire extraction interval (140 days), and slowlydecreased thereafter. In both the acidic and alkaline solutions, A1 wasmore soluble during the ea ly phases of the procedure but significantlydecreased i n concentrat ion with time. In contrast to the two alkalinesolutions produced by the llinois Basin fly ashes, the pH of the solutiongenerated by the lignite f y ash (W2) was essentially invariant for theentire solubilization-equi ibration interval (140 days). Moreover, thesolubility of A1 from the ignite sarople steadily increased with time.Other studies dealing with fly ash extracts have also noted analogouschanges in concentrations with time. Talbot et al. (1978) equilibrated awestern U.S. fly ash for 6 months in an open system. The pH of thealkaline extract decreased from 11 to 8.8 after 1 month, having reached asteady state.Townsend and Hodgson (1973) equilibrated an alkaline fly ash generated fromBri tish coals in a closed system. They observed that the pH and the OH andCa concentrations increased initially, and then became invariant, whereasthe B and SO concentrations decreased during the extraction interval.Helm et al. 41976) also noted that concentrations of SO4 and B decreasedwith time in solutions generated from shake tests with an alkaline fly ashproduced from eastern bituminous coals. Page et al. (1979) equilibrated a1:l fly ash-water mixture for 30 days. In the resulting alkaline solution,Ca and OH concentrations steadily decreased, whereas the pH remainedconstant.The present study may have several implications concerning the waterquality of ash disposal ponds in a chronological framework. The two flyashes that formed acidic extracts initially contained potentially toxictrace metals, such as Cd, dith time, these acidic solutions becameneutral, and several such trace constituents were no longer soluble,although other potential pollutants persisted in solution for longerperiods. The fly ashes that produced alkaline extracts generated solutionsthat reqained alkaline, and similarly, several potential pollutants alsopersisted in solution.These results indicate that fly ash, particularly acidic samples, are most .toxic to aquatic ecosystems when initially slurried to disposal ponds andthat their toxicity may decrease with time. However, if potentialpollutants are in metastable equilibrium in the pond, they may have longresidence times in the ash effluent, increasing the probability ofbioaccumulation by aquatic organisms. Excessive levels of Se have beendetected in various species of fish inhabiting a cooling lake associatedwith a coal-fired power plant in Illinois (Larimore and Tranquilli, 1979).Intermittent overflow of a nearby ash pond into the cooling lake may havebeen the source af the Se.The specific concentrations of the constituents exceeding EPM interimprimary or secondary drinking water standards or irrigation water criteriaare listed in Table 19. Depending on the solid waste, As, Cd, Cr, and Se
Page 1 and 2: lllinoiSTATSTAT
Page 3 and 4: V SURVEYatural Resources Building60
Page 5 and 6: TABLESSummary of the origin and gen
Page 7 and 8: The overall purpose of this investi
Page 9 and 10: steady state conditions in the disp
Page 11 and 12: total carbon determinations were ca
Page 13 and 14: y passing the extract through a col
Page 15 and 16: The GC-MS analyses were performed b
Page 17 and 18: with ultrapure water. The final HCl
Page 19 and 20: Be 3. Wlir~eraiogical composi'tion
Page 21 and 22: Table 6. Trace constituent concentr
Page 23 and 24: Table 7. Fly ash sample classificat
Page 25 and 26: Table 8. Carbon, sulfur, and benzen
Page 27 and 28: Wave number (cm-'Figure 8. Infrared
Page 29 and 30: Figure 12. HPLC chromatogram of the
Page 31 and 32: Figure 16. HPLC chromatogram of the
Page 34 and 35: Table 11. Organic components in the
Page 36 and 37: Figure 21. Gas chromatogram of the
Page 38 and 39: 4.Jrcrm c o mQU"* 'tn U.a-U U O NrO
Page 40 and 41: constituents. The amount of soluble
Page 42 and 43: Table 14. Change in chemical compos
Page 44 and 45: Table 16. Change in chemical compos
Page 46 and 47: Change in chemical composition as a
Page 50 and 51: Table 19. Corytituents in the long-
Page 52 and 53: Table 21. The LC-50 values, amount
Page 54 and 55: Table 23. The range of concentratio
Page 56 and 57: Table 25. The range of concentratio
Page 58 and 59: Table 27. The mean initial lengths
Page 60 and 61: Table 32. The mean final lengths an
Page 62 and 63: Several of the extrbivalves ( ~ are
Page 64 and 65: The mean concentrations of various
Page 66 and 67: 1972). Cadmium is a dangerous cumul
Page 68 and 69: Bl umer, M., 1957, Removal of eleme
Page 70 and 71: Furr, A. K-, T. F, Parkinson, R. A.
Page 72 and 73: Murtha, M. J., and G. Burnet, 1979,
Page 74 and 75: Standard methods for examination of

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