Page 514 - Materials Chemistry, Second Edition

CAT3525_C15.qxd 1/27/2005 12:40 PM Page 485
Incineration of Hazardous Wastes 485
generator of hazardous waste and must manage these residues in compliance with 40 CFR Parts 262
through 266.

15.5 MACT STANDARDS UNDER THE CAA
Hazardous waste incinerators, cement kilns, and certain aggregate kilns must also comply with
other emission limitations. The MACT emission standards are established within the CAA regula-
tions. Instead of using specific operating requirements to ensure that the unit meets performance
standards, the combustion facilities subject to MACT standards are permitted to use a specific pol-
lution control technology to achieve the stringent emission limits.

15.5.1 ORGANICS
To control the emission of organics, combustion units must comply with DRE requirements similar
to the RCRA requirements for hazardous waste combustion units. MACT combustion units must
select POHCs and demonstrate a DRE of 99.99% for each POHC in the hazardous waste stream.
Facilities that combust F020–F023 or F026–F027 hazardous waste are required to achieve a DRE of
99.9999% for each designated POHC. Additionally, for PCDDs and PCDFs, the U.S. EPA has prom-
ulgated more stringent standards under MACT. For example, MACT incinerators and cement kilns
that burn waste containing PCDDs or PCDFs must not exceed an emission limit of either 0.2 ng of
toxicity equivalence per dry standard cubic meter (TEQ/dscm) or 0.4 ng TEQ/dscm at the inlet to the
particulate control device. This unit of measure is based on a method for assessing risks associated
with exposures to PCDDs and PCDFs (U.S. EPA, 2002).

15.5.2 HYDROGEN CHLORIDE AND CHLORINE GAS
MACT combustion units do not use a tiered system to control HCl and chlorine gas emissions;
rather, facilities must ensure that the total chlorine emission does not exceed specific limits; for
example, the emission limit of total chlorine for a new incinerator is 21 ppmv. The facility may
achieve this emissions level by limiting or controlling the amount of chlorine-containing waste
entering the incinerator (U.S. EPA, 2002).

15.5.3 PARTICULATE MATTER
The EPA developed rather stringent standards for the control of particulate matter in order to limit
emissions of certain metals. For example, a new aggregate kiln cannot exceed an emission limit of
57 mg/dscm of particulate matter.

15.5.4 METALS
Hazardous waste incinerators, cement kilns, and aggregate kilns are not required to utilize the tiered
approach to control the release of toxic metals into the atmosphere. The MACT rule finalized
numerical emission standards for three categories of metals: mercury, low-volatile metals (arsenic,
beryllium, and chromium), and semivolatile metals (lead and cadmium). Combustion units must
meet emission standards for the amount of metals emitted. For example, a new cement kiln must
meet an emission limit of 120 µg/dscm for mercury, 54 µg/dscm for the low-volatile metals, and
180 µg/dscm for the semivolatile metals (U.S. EPA, 2002).

15.5.5 OPERATING REQUIREMENTS
To ensure that a MACT combustion unit does not exceed MACT emission standards, the unit must
operate under parameters demonstrated in a comprehensive performance test (CPT). Operating
parameters such as temperature, pressure, and rate of waste feed are then established, based on the