 Coalition for
Responsible Waste Incineration
INCINERATION AND THE COMBUSTION PROCESS
Incineration is one of the best methods of reducing the volume
and hazard of organic hazardous wastes. Through incineration, more than
90 percent of the volume of the original waste is typically reduced.
Any resulting residue (ash), if hazardous, is disposed of in a
licensed, secure landfill.
Matter is neither created nor destroyed in an incinerator.
Individual constituents are converted to more stable forms that are
less hazardous to human health and the environment. In addition, the
stable forms are more easily managed in an environmentally sound manner.
Wastewater treatment plants and landfills support incineration
in a comprehensive waste management system. Combustible constituents
are burned at incinerators; soluble constituents and suspended
particulates in wastewater are treated at wastewater treatment plants
and some residuals require landfilling.
PICs and POHCs
No process, including incineration, is 100 percent efficient.
Products of Incomplete Combustion (PICs) may be formed at trace
concentrations during incinerations of both hazardous and nonhazardous
wastes. PICs are organic compounds which are formed during partial
combustion due to incomplete mixing, insufficient time, or
insufficiently high temperatures, and are not completely destroyed.
PICs are more directly connected with how wastes are burned
rather than what is burned. For example, incomplete combustion of any
fuel or waste can generate carbon monoxide, smoke (carbon particles)
and a number of other partially burned organic compounds. PICs are
found in open burning of candles, fireplaces, outdoor grills and forest
fires. However, proper incineration design and operation minimizes PIC
formation as well as contains any of these byproducts in the enclosed
systems.
Hazardous wastes to be incinerated may contain Principal
Organic Hazardous Constituents (POHCs) that are carefully regulated.
POHCs are specific hazardous waste compounds identified by the EPA
which are selected for monitoring during the trial burn of a hazardous
waste incinerator. Typically, POHCs include the broad range of physical
and chemical characteristics of the wastes fed into the incinerator. In
addition, POHCs are selected to represent the quantity and quality of
compounds the incinerator is expected to handle during actual
operation. At least one of the compounds must be equally or more
difficult to burn than any waste to be burned in the unit. POHCs which
are present in the trial burn wastes in the greatest quantity and those
which are most toxic are often chosen for evaluation.
During the facility's trial burn, various wastes containing
POHCs are selected from a candidate list of approximately 500 for
testing. Once it is demonstrated that the facility is capable of
destroying these selected POHCs to an acceptable level, the
specifications are written into the operation permit. POHCs must be
destroyed and removed by at least 99.99 percent and sometimes even more
than 99.9999 percent. The later is the equivalent of burning 1,000,000
pounds of the constituent, treating the emissions, and leaving less
than a single pound. This destruction is achieved by operating at
temperatures ranging from approximately 1,600 to 2,000 degrees
Fahrenheit, while effectively mixing waste and air for a sufficient
amount of time.
Facilities for hazardous waste incineration are specifically
designed and operated to maximize destruction of POHCs and to minimize
formation of PICs to protect human health and the environment.
Furnaces, Boilers and Incinerators
The primary functions of furnaces, boilers and incinerators
are significantly different, although each plays an important role in
waste management. Furnaces are designed for converting secondary
materials into recoverable byproducts. Boilers recover energy through
combustion of fuels. Hazardous waste incinerators permanently reduce
the volume and toxicity of wastes. These industrial systems are
regulated under the Resource Conservation and Recovery Act (RCRA) as
well as certain provisions of the Clean Air Act. Boilers and industrial
furnaces burning hazardous waste are regulated under BIF (Boiler and
Industrial Furnace) regulations.
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