Fly ash dynamics in soil‐water systems

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Abstract
Among traditional fossil fuel sources, coal exists in quantities capable of supplying a large portion of our future energy needs. According to the President's National Energy Plan, annual productions of 1.2 × 109 t by 1989 and 1.91 × 109 t by the year 2000 are anticipated. It appears reasonable to expect an increase in the percentage as well as the number of coal‐fired power plants. The increased use of coal will produce additional quantities of fly ash, one of the waste products of burning pulverized coal. Fly ash constitutes about 70% of the total amount of residue generated in coal‐fired power plants equipped with electrostatic precipitators or bag filters. Fly ash contains various substances of which trace metals, although present in a small fraction, are of special interest due to their cumulative build up, long life, and high toxicity to man, plants, and animals through air, water, and soil. Several estimates made by the Bureau of Mines suggest that the fly ash released into the atmosphere appears to be about 5 to 10% of the total ash in coal, and the solid waste produced in the form of ash after the combustion of coal is about 25 to 30%. Presently, less than 10% of the fly ash collected is utilized in some process other than direct burial. Since there is no consistent trend of effective utilization, the accumulating fly ash becomes a significant waste disposal problem. This paper deals with the fate and dynamics of fly ash in air, water, and land from the environmental deterioration point of view; however, optimism on its possible usefulness has not been ignored.