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Incineration of Hazardous Wastes 479
with gases as particulate matter. These particles, collectively referred to as “fly ash,” are collected
in the pollution control devices in accordance with RCRA regulations.
As a hazardous waste management practice, incineration has several unique attributes. If con-
ducted under optimum conditions, controlled incineration permanently destroys toxic organic com-
pounds within waste by converting them into stable molecules. Second, incineration reduces the
volume of hazardous waste. Land disposal of ash, as opposed to the disposal of untreated hazardous
waste, is therefore safer and should reduce long-term liability to the waste generator. Incineration,
however, does not destroy inorganic compounds within the waste such as metals. In fact, the residue
becomes more concentrated with the various nonburnables after the organic component has been
destroyed. Ash from incinerators is subject to applicable RCRA standards and may need to be
treated for metals or other inorganic constituents prior to land disposal.

15.3 OVERVIEW OF REGULATORY REQUIREMENTS
Emissions from hazardous waste combustors are regulated under two statutory authorities, RCRA
and the Clean Air Act (CAA). Relevant RCRA regulations include 40 CFR Part 264, Subpart O and
Part 265, Subpart O for incinerators, and 40 CFR Part 266, Subpart H for boilers and industrial fur-
naces (BIFs). RCRA requirements for these units are provided in 40 CFR Part 270. All of these units
are subject to the general treatment, storage, and disposal facility (TSDF) standards under RCRA.
Hazardous waste incinerators and hazardous waste burning cement kilns and lightweight aggregate
kilns are also subject to the CAA maximum achievable control technology (MACT) emission stan-
dards. The MACT standards set emission limitations for polychlorinated debenzodioxins (PCDDs),
polychlorinated dibenzofurans (PCDFs), metals, particulate matter, total chlorine, hydrocarbons,
carbon monoxide, and destruction and removal efficiency (DRE) for organic emissions. The com-
bustion standards under RCRA and the MACT standards under the CAA are discussed below.

15.4 COMBUSTION STANDARDS UNDER RCRA, SUBPART O
To minimize potential harmful effects of incinerator gaseous emissions, the U.S. EPA has developed
performance standards to regulate four pollutant categories: organics, hydrogen chloride and chlo-
rine gas, particulate matter, and metals (40 CFR Part 264.343). Boilers and most industrial furnaces
are assigned performance standards. For each category or type of emission, the regulations estab-
lish compliance methods and alternatives.
The Subpart O standards apply to facilities that destroy hazardous wastes, and regulate the
emissions from incinerator combustion processes. An incinerator burning hazardous waste must be
designed, constructed, and operated so that the performance standards outlined below are met.
Specifically, the RCRA regulations restrict gaseous emissions of organic compounds, hydrogen
chloride (HCl), particulate matter, fugitive emissions, and metals. All hazardous waste incinerators
must conform to the requirements of Subpart O unless the waste is considered “low risk” (40 CFR
Part 264.340). These include certain listed hazardous wastes (Subpart D) or those characterized as
hazardous due to ignitability or corrosivity. Incinerators in existence from May 19, 1980 were
allowed to continue burning hazardous waste if the units complied with the Part 265, Subpart O
interim status standards. However, on November 8, 1989, the interim status was terminated for all
existing hazardous waste incinerators unless the facility submitted a Part B permit application by
November 8, 1986 (§270.73(f)). Due to this deadline, there are very few incinerators presently oper-
ating under interim status (U.S. EPA, 2000).

15.4.1 ORGANIC COMPOUNDS
To obtain an operating permit, an incineration facility must demonstrate that the emission levels for
selected hazardous organic constituents are within applicable limits. The main indicator of incinerator