Literature Cited (1) “Adoption of a System for the Classification of Organic Compounds According to Photochemical Reactivity”, Staff Report #76-3-4, State of California, Air Resources Board, El Monte, Calif., Feb. 19, 1976. ( 2 ) Dimitriades, B., “Proceedings of the Solvent Reactivity Conference”, EPA-65013-74-010, Nov. 1974. (3) Zafonte, L., Rieger, P. L., Holmes, J. R., Enuiron. Sci. Technol., 11 ( 5 ) ,483 (1977).
(4) Shikiya, J. M., Daymon, D., Faigin, H., “The Hi-Vacuum Irradiation Chamber”, Publ. No. DTS-76-19, State of California, Air Resources Board, El Monte, Calif. (5) Gorse, R. A., Volman, D. H., J . Photochem., 3, 115 (1974). (6) Doyle, G. J.,Lloyd, A. C., Darnall, K. R., Winer, A. M., Pitts, J. N., Jr., Enuiron. Sei. Technol., 9,237 (1975).
Received for review January 12, 1977. Accepted May 9, 1977.
Comparison of Levels of Trace Elements Extracted from Fly Ash and Levels Found in Effluent Waters from a Coal-Fired Power Plant David R. Dreesen’, Ernest S. Gladney, James W. Owens, Betty L. Perkins, Caroline L. Wienke, and Lawrence E. Wangen Environmental Studies Group, M.S. 490, Los Alamos Scientific Laboratory, P.O. Box 1663, Los Alamos, N.M. 87545 Trace elements were extracted from a coal-fired power plant electrostatic precipitator ash with nitric acid, hydrochloric acid, citric acid, redistilled water, and ammonium hydroxide as extractants. Effluent waters at this plant were sampled to assess the elevation of trace element concentrations compared with intake waters. The results showed a positive correlation between those elements most extractable by water (B, F, Mo, and Se) or acid (As, B, Cd, F, Mo, and Se) and those elements most elevated in effluent waters (As, B, F, Mo, and Se). The expanding use of coal for electric power generation in the southwestern US., along with the high ash content of these coals, will necessitate the disposal of massive amounts of coal ash. The possible contamination of waters and soils by such coal ash disposal requires investigation. The solubility behavior of trace elements in the alkaline waters of this region may indicate that different elements are of concern here than those found in more acidic aquatic environments. A study has been initiated to identify which trace elements are most extractable from ash and to compare them with those elements that are observed at elevated concentrations in effluent waters from a coal-fired power plant in the southwestern U.S.
Experimental Methods Electrostatic precipitator ash for the extraction experiment, influent waters, and effluent waters were collected a t a large coal-fired power plant at Fruitland, N.M. A flow diagram of water usage a t this plant is given as Figure 1. Influent and effluent waters were sampled at four locations: (A) cooling lake intake; (B) cooling lake outlet a t the base of the dam; (C) decant channel-effluent water from the ash settling pond; and (D) ash pond-surface water. Ash slurry from the venturi scrubbers is sent to the ash pond where the ash settles and the water is decanted. Surface water in the ash pond was sampled for comparison with ash pond effluent water in the decant channel. The outlet of the cooling reservoir was sampled for comparison with cooling lake intake and ash pond effluent, as well as to approximate scrubber intake water. Coal ash effluents discharged into the cooling lake (1) may also influence trace element concentrations in the outlet. Each sample was filtered in the field with a Whatman No. 41 prefilter, a 0.45-1m Millipore membrane filter, and a backing pad; the filtered samples were acidified in the field and later frozen. The sampling train and bottles were made from plastic materials.
Trace elements in the precipitator ash were extracted using an ash-to-extractant ratio of 1:4. The extractants included 0.1 M H3C&07 (citric acid), 1.0 M HC1, 1.0 M “03, 0.1 M HN03, 0.01 M “OB, 0.001 M HN03, redistilled H20, and 0.1 M NH40H. The ash-extractant mixture was agitated for 3 h and then filtered through Whatman No. 41 followed by Whatman No. 542 filter paper. The filtrates were acidified and frozen in polyethylene bottles. Complete details of the extraction experiment are reported elsewhere (2).
Analytical Procedures Fluoride was measured in the sample solutions with an Orion Model 94-09A specific ion electrode and a Corning Model 112 digital volt meter ( 3 ) .The boron content was determined by thermal neutron capture prompt y-ray analysis ( 4 ) by evaporating 10 mL of the solutions to dryness on small polyethylene sheets. The capture y-ray facility at the Los Alamos Omega West Reactor was described by Jurney et al. (5). The remaining elements in solution were measured by flameless atomic absorption with a Perkin-Elmer Model 306 spectrophotometer equipped with a deuterium background corrector and a HGA-2000 graphite furnace. Perkin-Elmer electrodeless discharge lamps were used for As, Cd, and Se determinations, and Perkin-Elmer hollow cathode lamps were SAN JUAN R I V E R
AOUEDUCl
-
-
0 L 4
(El d
5
OUTLET CHANNEL
w
COOL I NO LAKE
DAM
5 A
a 1,
-
Y
INTAKE CANAL
I
w
(cl_ DECANT 1, CHANNEL
ASH POND
(D1
“
DISCHARGE CANAL
-
A
ASH SLURRY CHANNEL
POWER PLANT
Volume 11, Number 10, October
1977
1012
Table 1. Percentage of Trace Element Content of Ash Extracted by Each Solution and Trace Element Content of Precipitator Ash Molarity
1.0 M
Solution
"03
1.0 M
0.1 M
0.1 M
0.01 M
nci,
Cltric acid
HNO3
"03
0.001 M
0.1 M
HNO3
H20
NH40H
Initial pH a
0.5
0.5
2.2
1.4
2.2
3.1
7.4
11.3
Final pH
0.5
0.6
3.6
4.1
11.9
Oh
Oh
%
11.9 %
11.9
Oh
11.7 %
Oh
Yo
0.31 3.9
