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Emerging Pollution Control Technologies 479

will have lower pressure drop than filters in series, whereas series filter will achieve a
higher PM collection efficiency than filters in parallel. The housing unit for parallel filters
will be larger than the housing unit for series filters.

9.2. Application to Air Emission Control
The use of HEPA filters for the control of PM provides advantages/disadvantages,
which are listed in Table 3. A list of remediation technologies that are compatible with

Table 3
Advantages and Disadvantages of HEPA Filters
Advantages Disadvantages
• Easy to operate. • Many require prefilters for exhaust with high
PM concentrations.
• Provide 99.9% or greater PM removal • Required housing units are expensive and may
efficiencies. be subject to corrosion.
• Filters are subject to fouling by high-humidity
exhaust gases.
• Filters must be replaced periodically because
of plugging caused by PM.
• High power costs because of pressure drop
across filter.

Table 4
Compatibilities of HEPA Filters with Remediation Technologies
Emission source Qualifications
Asbestos removal from building During the asbestos removal, HEPA filters must either
be installed in the building ventilation system or in
the negative air pressure system.
A bag-out housing units will be required for HEPA
filters and filter must be disposed of properly.
Enclosure ventilation system Inlet air with high PM concentrations may require
pre-filters.
Bag-out housing units may be required for
characteristics of PM (e.g, heavy metal or SVOC
contamination).
The lifetime of the HEPA filter will be shorten under
high-humidity application.
Hoods or enclosures of solidification/ Lime used in the process may subject the HEPA
stabilization mixing bins housing to corrosion.
Inlet air with high PM concentrations may require
pre-filters.
Bag-out housing units may be required for
characteristics of PM (e.g. heavy metal or SVOC
contamination).
The lifetime of the HEPA filter will be shorten under
high humidity application.