Page 174 - Wastewater Solids Incineration Systems

Emission Control and Monitoring 141

time and allows the CO and other volatilized organics to fully burn out. Carbon
monoxide emissions from a fluid bed incinerator are invariably less than 45 mg/Nm 3
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dv (50 ppm dv ) and in many cases less than 9 mg/Nm dv (10 ppm dv ); mass
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emission rates are typically less than 0.5 g/kg (1.0 lb/dry ton) of solids incinerated.
For a new facility, state regulatory agencies typically will require a CO emission limit
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of 90 mg/Nm dv (100 ppm dv ). A fluid bed incinerator can easily meet this limit.
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An MHF would require an afterburner operating at a minimum of 816°C (1500°F) to
meet this standard.
1.2.3 Volatile Organic Compounds
Volatile organic compounds, like CO, are PICs that result from the vaporization of
organic matter in the feed cake and partial oxidation of the volatilized com-
pounds. As previously stated, incomplete combustion is caused by inadequate
combustion conditions in the incinerator, such as insufficient temperature, resi-
dence time, or mixing.
Chemically, VOCs consist of a variety of compounds, including the following:

• Straight and branched chain aliphatic hydrocarbons (methane, ethane, acety-
lene, etc.).
• Oxygenated hydrocarbons (acids, aldehydes, ketones, etc.).
• Chlorinated hydrocarbons (perchloroethylene, trichloroethane, etc.).
• Saturated and unsaturated ring compounds (benzene, toluene, phenols, etc.).

Volatile organic compounds are regulated under the Part 503 regulations (U.S.
EPA, 1993), which require that total hydrocarbons emitted from an incinerator must
be less than 100 ppm as propane on a dry volume basis corrected to 7% oxygen (i.e.,
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100 ppm dv [140 mg/Nm dv ]).
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Because of the different combustion conditions that exist in an MHF and fluid
bed incinerator, VOC emissions from an MHF and fluid bed incinerator are dif-
ferent. The upper drying hearths of an MHF typically will have sufficient tempera-
tures to volatilize organic compounds but insufficient temperatures to fully oxidize
them. In general, VOC emissions from an MHF will vary significantly on a daily
basis depending on the feed cake rate and combustion characteristics (percent
solids, percent volatile solids, and heating value) and furnace operating conditions
(hearth temperatures, excess air level, burner firing rates on different hearth levels).
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Some MHFs can, however, meet the 140-mg/Nm dv (100-ppm dv ) standard
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