MIL-HDBK-1003/7
17.4
Solid Waste Disposal
Solid Waste Production. The sources and amounts of solid waste produced by a
17.4.1
fossil-fueled steam power plant are dependent mainly on the fuel type, fuel burn rate,
and degree of pollutant removal from the boiler exhaust. Other factors, such as fuel-
burning equipment, may also affect the solid waste production rate. Solid wastes
produced at a plant burning fossil fuel include fly ash, bottom ash, pulverizer rejects
(if pulverized coal is burned), and flue gas desulfurization scrubber solids (if an FGD
device is employed).
17.4.1.1 Fly Ash. Fly ash consists of the fine ash particles that are entrained in the
boiler exhaust gases. For further information, see Combustion Engineering, Combustion
Fossil Power Systems, and Boiler Emissions in TM-5-815-1/AFR 19-6. Particulate
emissions from natural-gas-fired boilers are negligible and thus are not a source of
solid waste.
17.4.1.2 Bottom Ash. Bottom ash consists of the large particles of solid combustion
products (ash) and unburned carbon that fall out in the bottom of the boiler.
17.4.1.3 Pulverizer Rejects. Pulverizer rejects consist of a variety of coarse, heavy
pieces of hard rock or slate and iron pyrite that are separated from coal during
pulverization. The amount produced varies with the particular coal being pulverized. A
reasonable estimate can be made, however, if it is assumed that rejects comprise 0.5
percent of the coal fired.
17.4.1.4 FGD Scrubber Solids. Solids from an FGD device consist of sulfate and sulfite
reaction products resulting from the absorption of sulfur dioxide from the boiler
exhaust. The particular solids formed depend on the scrubber type. See MIL-HDBK-
1003/6, Section 7.4, for details of scrubber waste products for various types of SO2
scrubbers. The quantity of scrubber solids produced vary with the amount of SO2 removed
from the boiler exhaust and with the type of solids produced. Generally, a mass balance
calculation is required to determine the quantity of scrubber solids generated.
17.4.2
Methods of Treatment and Disposal
17.4.2.1 Requirements. At this time, the solid wastes produced at a fossil-fueled
steam power plant are not categorized as hazardous by the Environmental Protection
Agency. Therefore, according to the Resource Conservation and Recovery Act (RCRA) of
1976, the wastes may be landfilled utilizing environmentally acceptable practices.
Since RCRA requires that a landfill not contaminate an underground drinking water source
beyond the solid waste boundary, leachate control must be incorporated. This is usually
accomplished through the use of liners, either clay or a synthetic membrane.
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