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Miscellaneous Organic Chemical Manufacturing
NESHAP (MON) Summary
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2. What Are the Emission Limits and Work Practice Standards?
The final rule regulates HAP emissions from miscellaneous
organic chemical manufacturing facilities that are determined
to be major sources. The standards apply to existing sources
as well as new sources.
Process Vents
 The final standards for existing batch and continuous process
vents are set at a floor level of control and include requirements
for organic and inorganic HAP. For batch process vents, the
final standards require sources to reduce uncontrolled organic
HAP emissions from the sum of all batch process vents within
the process by 98 percent if uncontrolled emissions exceed
4,540 kilograms per year (kg/yr) (10,000 pounds per year
(lb/yr)). No control of vents is required for processes that
are limited to uncontrolled emissions of 4,540 kg/yr (10,000
lb/ yr) or less, as calculated on a rolling 365-day basis.
A second control option for batch vents is to reduce the
sum of all batch process vents within the process by 95 percent
using recovery devices.
For continuous process vents, the final standards require
control of vents determined to have a total resource effectiveness
(TRE) index equal to or less than 1.9. Total resource effectiveness
(TRE) index means a measure of the supplemental total resource
requirement per unit reduction of total organic compound
(TOC) associated with an individual air oxidation vent
stream, based on vent stream flow rate, emission rate of
TOC, net heating value, and corrosion properties (whether
or not the vent stream is halogenated), as quantified by
the equation given under 40
CFR 60.614(e). The standards require you to reduce
HAP emissions by at least 98 percent by weight if the TRE
of the outlet gaseous stream after the last recovery device
is less than 1.9, or to reduce the outlet TOC concentration
to 20 parts per million by volume (ppmv) or less. For continuous
process vents, the US EPA referenced the process vent standards
contained in 40
CFR 63.980 subpart SS.
 For
inorganic HAP, the US EPA set the standards based on the
floor and made no distinction between batch and continuous
streams. The standards for hydrogen halide and halogen
HAP (i.e., HCl, hydrogen fluoride (HF), and chlorine (C12))
were determined to be 99 percent control of hydrogen halide
and halogen HAP from the sum of all process vents in processes
with uncontrolled hydrogen halide and halogen HAP emissions
equal to or greater than 1,000 lb/yr. The final rule also
requires control of hydrogen halide and halogen HAP emissions
generated by the combustion control of halogenated streams,
which are defined by a mass emission rate of halogen atoms
contained in organic compounds of 0.45 kilograms per hour
(kg/hr) or more. Specifically, hydrogen halide and halogen
HAP emissions must be reduced after the combustion device
by 99 percent, to no more than 0.45 kg/hr, or to no more
than 20 ppmv. Alternatively, the halogen atom mass rate
before the combustion device may be reduced to no more
than 0.45 kg/hr or to no more than 20 ppmv. The MACT floor
for PM HAP emissions from process vents at existing sources
is no emissions reduction, and a standard was not set above
the floor.
The final rule defined the term process to include all
equipment that collectively function
to produce a material or family of materials that are covered
by the source category. For batch process vents, the rule
also establishes an equivalent mass cutoff of 200 lb/yr
in the final rule that corresponds to the 50 ppmv concentration.
 The new source standards for batch and continuous process
vents follow the same formats as described above. However,
some of the applicability triggers are more stringent.
All batch process vents within a process for which the
uncontrolled organic HAP emissions from batch process vents
exceed 1,360 kg/yr (3,000 lb/yr) must be reduced by either
98 percent using a control device or 95 percent using a
recovery device. All continuous process vents with a TRE
of less than or equal to 5.0 must be controlled by 98 percent.
For inorganic HAP, the standards for new sources are identical
to the standards for existing sources. The new source standard
for particulate matter (PM) HAP emissions from process
vents is 97 percent control for each process with uncontrolled
PM HAP emissions greater than or equal to 400 lb/yr. Control
requirements for halogenated streams are also the same
as for existing sources.
Storage Tanks
The final rule requires existing sources to control
emissions from storage tanks having capacities greater
than or equal to 38 cubic meters (m3) (10,000
gallons (gal)) and storing material with a HAP partial
pressure of greater than 6.9 kilopascals (kPa) (1.0 pound
per square inch absolute (psia)). For new sources, the  standards
require control of storage tanks having capacities greater
than or
equal to 38 m3 (10,000 gal) and storing material
with a HAP partial pressure of greater than 0.7 kPa (0.1
psia). For both existing and new sources, the required
control is to use a floating roof or to reduce the organic
HAP emissions by 95 percent by weight or more. The US EPA
concluded in a revised analysis that for small storage
tanks (capacities <10,000 gal), that there is a "no
emission reduction"
MACT floor, and they did not specify a standard because
the total impacts of a more stringent regulatory alternative
were found to be unreasonable. Additionally, the US EPA
concluded that the new source MACT floor as proposed is
appropriate (95 percent control of all tanks with capacities
of 10,000 gal and storing material with a HAP partial pressure
of 0.1 psia) for all tanks.
Wastewater
The final rule requires management and treatment
of Group 1 wastewater streams and residuals removed from
Group 1 wastewater streams to be consistent with the requirements
contained in 40
CFR part 63, subpart G. For the purposes of 40 CFR part
63, subpart FFFF (MON), the characteristics of Group 1 wastewater
streams are defined
with the following characteristics at the point of determination
(POD):
- Process wastewater containing partially soluble HAP
at an annual average concentration greater than 50 parts
per million by weight (ppmw) and a combined total annual
average concentration of soluble and partially soluble
HAP of 10,000 ppmw or greater at any flowrate.
- Process wastewater containing partially soluble HAP
at an annual average concentration greater than 50 ppmw
and a combined total annual average concentration of
soluble and partially soluble HAP of 1,000 ppmw or greater
at an annual average flowrate of 1 liter per minute (lpm)
or greater.
- Process wastewater containing partially soluble HAP
at an annual average concentration of 50 ppmw or less
and soluble HAP at an annual average concentration of
30,000 ppmw or greater and a total annual load of soluble
HAP of 1 tpy or greater.
 At new sources, the requirements are identical to those for
existing sources, but the applicability triggers on individual
streams are more stringent. In addition to controlling streams
that meet the thresholds for existing sources, control is
also required for the following streams at their POD:
- Process wastewater containing an annual average HAP
concentration exceeding 10 ppmw
of compounds listed in Table
8 of 40 CFR part 63, subpart G, with annual average
flowrate greater than 0.02 lpm.
- Process wastewater containing partially soluble HAP
at an annual average concentration of 50 ppmw or less
and soluble HAP at an annual average concentration of
4,500 ppmw or greater and a total annual load of soluble
HAP of 1 tpy or greater.
The final rule also requires compliance with the requirements
of 40
CFR 63.105 for maintenance wastewater streams,
and compliance with the requirements in 40
CFR 63.149 for liquid streams in open systems
within an MCPU.
Transfer Racks and Ancillary Sources
 The
final standards for transfer racks, maintenance wastewater,
and heat exchange systems are unchanged from the proposal,
and they are identical to the requirements in the hazardous
organic NESHAP (HON). For transfer operations, we are
requiring the HON level of control for transfer racks
that load greater than 0.65 million liters per year
(l/yr) (0.17 million gallons per year (gal/yr)) of
liquid products that contain organic HAP with a partial
pressure of 10.3 kPa (1.5 psia). For each transfer
rack that meets these thresholds, total organic HAP
emissions must be reduced by 98 percent by weight or
more, or the displaced vapors must be returned to the
process or originating container. For maintenance wastewater,
you must prepare a plan for minimizing emissions. For
heat exchange systems, you must implement a monitoring
program to detect leaks into the cooling water.
Equipment Leaks
For equipment leaks, the final rule requires implementation
of a leak detection and repair (LDAR) program. For processes
with no continuous process vents, you must implement the
program in 40
CFR part 63, subpart TT. For processes with at least
one continuous process vent, you must implement the program
in 40
CFR part 63, subpart UU. Alternatively, you may elect
to comply with the requirements in 40
CFR part 65, subpart F (i.e., the Consolidated Federal
Air Rule).
Pollution Prevention
 The final rule also includes a pollution prevention
alternative for existing sources that meets the control
level of the MACT floor and may be implemented in lieu
of the emission limitations and work practice standards
described above. The pollution prevention alternative provides
a way for facilities to comply with MACT by reducing overall
consumption of HAP in their processes; therefore, it is
not applicable for HAP that are generated in the process
or for new sources.
Specifically, you must demonstrate
that the production-indexed consumption of HAP has decreased
by at least 65 percent from a 3-year average baseline set
no earlier than the 1994 through 1996 calendar years. The
production-indexed consumption factor is expressed as the
mass of HAP consumed, divided by the mass of product produced.
The numerator in the factor is the total consumption of
the HAP, which describes all the different areas where
it can be consumed, either through losses to the environment,
consumption in the process as a reactant, or otherwise
destroyed.
Emissions Averaging Provisions
The final rule incorporates the emissions averaging
provisions in 40 CFR part 63, subpart G (the HON), with
some changes to accommodate batch process vents. For example,
the final rule specifies that uncontrolled emissions from
batch process vents are to be calculated using the procedures
in 40
CFR part 63, subpart GGG (pharmaceutical), and performance
testing must be conducted under worst case conditions,
as defined in subpart
GGG.
Alternative Standard
The final rule contains an alternative standard for process
vents and storage tanks. When emissions are controlled
using combustion control devices, the alternative standard
requires control to an undiluted TOC concentration of 20
ppmv or less and an undiluted hydrogen halide and halogen
HAP concentration of 20 ppmv or less. For noncombustion
control devices, the TOC concentration and total hydrogen
halide and halogen HAP concentration both must be reduced
to 50 ppmv or less. Continuous monitoring of outlet TOC
and total hydrogen halide and halogen HAP is required for
compliance with this alternative standard.
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