United States
Environmental Protection
Agency
Office of Pesticides
and Toxic Substances
EPA 560/4-88-004q
March 1988
v°/EPA Title 111 Section 313
Release Reporting
Guidance
Estimating Chemical Releases From
Rubber Production and Compounding
Emergency Planning and
Community Right-to-Know Act of 1986
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Estimating Chemical Releases From
Rubber Production and Compounding
Facilities engaged in rubber production
and compounding may be required to report
annually any releases to the environment of
certain chemicals regulated under Section
313, Title III, of the Superfund Amendments
and Reauthorization Act (SARA) of 1986. If
your facility is classified under SIC codes 20
through 39 (rubber production and com-
pounding facilities generally fall under SIC
codes 2822 and 2830) and has 10 or more
full-time employees, for calendar year 1987
you must report all environmental releases of
any Section 313-listed chemical or chemical
category manufactured or processed by your
facility in an amount exceeding 75,000
pounds per year or otherwise used in an
amount exceeding 10,000 pounds per year.
For calendar years 1988 and 1989 (and
beyond), the threshold reporting quantity for
manufactured or processed chemicals drops
to 50,000 and 25,000 pounds per year,
respectively.
This document has been developed to
assist those who produce rubber in the
completion of Part III (Chemical Specific
Information) of the Toxic Chemical Release
Inventory Reporting Form. Included herein is
general information on toxic chemicals used
and process wastes generated, along with
several examples to demonstrate the types of
data needed and various methodologies
available for estimating releases. If your
facility performs other operations in addition
to rubber production, you must also include
any releases of toxic chemicals from these
operations.
Step One
Determine if your facility processes or
uses any of the chemicals sun/ect to
reporting under Section 313.
A suggested approach for determination
of the chemicals your facility uses that could
be subject to reporting requirements is to
make a detailed review of the chemicals and
materials you have purchased. If you do not
know the specific ingredients of a chemical
formulation, consult your suppliers for this
information. If they will not provide this in-
formation, you must follow the steps outlined
to handle this eventuality in the instructions
provided with the Toxic Chemical Release
Inventory Reporting Form.
The list presented here includes chemi-
cals typically used in rubber production that
are subject to reporting under Section 313.
This list does not necessarily include all of
the chemicals your facility uses that are
subject to reporting, and it may include many
chemicals that you do not use. You should
also determine whether any of the listed
chemicals are created during processing at
your facility.
Synthetic rubber manufacturing
Monomers: 1,3-butadiene, styrene,
acrylonitrile, ethylene, ethylene glycol,
propylene glycol, propylene, 1,3-toluene
diisocyanate, ethylene dichloride,
epichlorohydrin, acrylic acid, ethyl
acrylate; butyl acrylate, chloroprene,
ethylene oxide
Retarders: Phthalic anhydride,
n-nitrosodiphenylamine
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Catalysts: Cobalt compounds, nickel
compounds, titanium tetrachloride
Antioxidants: Phenylene diamine
Short stops: Hydroquinone
Solvents: Toluene, methyl chloride
(chloromethane) ,1,1,2-trichloroethane
Cooling tower corrosion inhibitors:
Chromium compounds, zinc compounds
Miscellaneous chemicals: Sodium
hydroxide, sulfuric acid, various additives
Rubber compounding
Processing aids: Zinc compounds
Accelerators: Zinc compounds, ethylene
thiourea, diethanolamine
Age restorers: Nickel compounds,
hydroquinone, phenol, alpha-
naphthylamine, p-phenylenediamine
Vulcanizing agents: Selenium
compounds, zinc compounds, lead
compounds
Initiator: Benzoyl peroxide
Accelerator activators: Zinc com-
pounds, lead compounds, ammonia
Plasticizers: Dibutyl phthalate,
dioctylphthalate, bis (2-ethylhexyl
adipate)
Miscellaneous ingredients: Titanium
dioxide, cadmium compounds, organic
dyes, antimony compounds
Step Two
Determine if your facility surpassed the
threshold quantities established for
reporting of listed chemicals last year.
You must submit a separate Toxic Chemi-
cal Release Inventory Reporting Form for
each listed chemical that is "manufactured,"
"processed," or "otherwise used" at your
facility in excess of the threshold quantities
presented earlier. Manufacture includes
materials produced as byproducts or impu-
rities. Toxic compounds that are incorpo-
rated into your products (for example,
monomers, plasticizers, and vulcanizing
agents) would be considered "processed"
because they become part of the marketed
finished product. Acids, caustics, solvent
carriers, degreasing solvents, cleaning agents,
and other chemicals that do not become part
of the finished product would be considered
"otherwise used."
The amount of a chemical processed or
otherwise used at your facility represents the
amount purchased during the year, adjusted
for beginning and ending inventories. To
ascertain the amount of chemical in a mixed
formulation, multiply the amount of the
mixture (in pounds) by the concentration of
the chemical (weight percent) to obtain the
amount of chemical processed.
Example: Calculating annual use of
sodium hydroxide at a synthetic
rubber manufacturing facility.
In 1987, a synthetic rubber plant
purchased 70,000 gallons of a 50 percent
sodium hydroxide solution for use in its
caustic washing process. At the beginning
of the year, 10,000 gallons of this solution
was in storage, and 5,000 gallons re-
mained in storage at the end of the year.
According to Section 313 definitions,
sodium hydroxide is considered "otherwise
used" in this process. The quantity of
sodium hydroxide otherwise used during
the year can be estimated by the following
calculation:
Annual usage of solution =
10,000 gallons (beginning inventory) +
70,000 gallons (purchased) -
5,000 gallons (ending inventory)
= 75,000 gallons
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Amount qfNaOH used =
75,000 gallons ofNaOH solution x
1.5253 (specific gravity of
50%NaOH) +
8.33 Vb/gal (density of water) x
0.5 Ib NaOH/1 Ib solution
= 476,866 Ib
A listed chemical may be a component of
several formulations you purchase, so you
may need to ask your supplier for informa-
tion on the concentration (percentage) of the
chemical in each. For chemical categories,
your reporting obligations are determined by
the total amounts of all chemicals in the
category.
You must complete a report for each
chemical for which a threshold is exceeded.
The thresholds apply separately; therefore, if
you both process and use a chemical and
either threshold is exceeded, you must report
for both activities. If neither threshold is
exceeded, no report is needed.
Step Three
Identify points of release for the
chemical(s) subject to reporting.
An effective means of evaluating points of
release for listed toxic chemicals is to draw a
process flow diagram identifying the opera-
tions performed at your facility. The figures
presented in this pamphlet are example flow
diagrams for synthetic rubber production by
the emulsion production process. Because
each facility is unique, you are strongly urged
to develop a flow diagram for your particular
operations that details the input of materials
and chemicals and the waste sources re-
sulting from the operation of each unit.
Releases from synthetic rubber produc-
tion are primarily in the form of wastewater.
Wastewater from these facilities comes from
one of three sources: 1) utility wastewater,
such as cooling tower blowdown; 2) process
wastewater, such as the decant water from
solvent separators; and 3) wastewater from
equipment and area washdowns. Process
wastewater and equipment cleanup waste-
water are usually combined in a single plant
effluent stream.
Solid wastes in this production process
are present primarily as suspended solids in
plant wastewater. The rubber solids that
collect on much of the process equipment are
either removed by hand or washed off with
water and discarded in the general plant
wastewater. These solids are subsequently
removed from the wastewater treatment plant
as sludge.
Atmospheric releases (primarily mono-
mers) generally emanate from the monomer
recovery process, absorber vents, and drying
operations. Fugitive emissions of gaseous
organic compounds are possible from vir-
tually all of the processes associated with
synthetic rubber manufacturing. These
fugitive emissions include minor leaks to the
atmosphere from pumps, relief valves and
fittings, and from loading, unloading, and
storage operations.
Releases from rubber compounding
facilities are primarily in the form of fugitive
air emissions and solid wastes. Fugitive air
emissions occur primarily from mixing opera-
tions. Solid wastes generally occur in the
form of scrap and scorched rubber; dusts and
powders from fabric filters in the mixing and
compounding areas and from unloading,
storage, and equipment cleanup operations;
and contaminated lubricating oil "oozings"
from process mixers.
Your reporting must account for all
releases.
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AIR RELEASE
CAUSTIC
UNINHIBITED MONOMER
PRODUCT
SHIPMENTS
WASTEWATER
Example Flow Diagram for Crumb Rubber Production by Emulsion Polymerization
(adapted from Source Assessment: Rubber Processing State-of-the-Art)
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CARBON BLACK
OIL
RUBBER, POLYMERS
MISC. CHEMICALS
BANBURY
RUBBER
MIXING
I
AIRBORNE PARTICULATE
TO FABRIC FILTER
T
FINISHED
PRODUCT
SPILLS, LEAKS,
FUGITIVE LOSSES
OF DRY CHEMICALS
SCRAP
RUBBER
Example Plow Diagram of Rubber Compounding Process
Step Four
Estimate releases of toxic chemicals.
After all of the toxic chemicals and waste
sources have been identified, you can esti-
mate the releases of the individual chemicals.
Section 313 requires that releases to air,
water, and land and transfers to offsite
facilities be reported for each toxic chemical
meeting the threshold reporting values. The
usual approach entails first estimating re-
leases from waste sources at your facility
(that is, wastewater, air release points, and
solid waste) and then, based on the disposal
method used, determining whether releases
from a particular waste source are to air,
water, land, or an offsite disposal facility.
In general, there are four types of release
estimation techniques:
• Direct measurement
• Mass balance
• Engineering calculations
• Emission factors
Descriptions of these techniques are provided
in the EPA general Section 313 guidance
document. Estimating Releases and Waste-
Treatment Efficiencies for the Toxic Chemical
Release Inventory Form.
Provisions of the Clean Air Act, Clean
Water Act, Resource Conservation and
Recovery Act, and other regulations require
monitoring of certain waste streams. If
available, data gathered for these purposes
can be used to estimate releases. When only
a small amount of direct measurement data
is available, you must decide if another esti-
mation technique would give a more accurate
estimate. Mass balance techniques and
engineering assumptions and calculations
can be used in a variety of situations to
estimate toxic releases. These methods of
estimation rely heavily on process operating
parameters; thus, the techniques developed
are very site-specific. Emission factors are
available for some industries in publications
referenced in the general Section 313 guid-
ance document. Also, emission factors for
your particular facility can be developed in-
house by performing detailed measurements
of wastes at different production levels.
The complexity of the rubber manufac-
turing and compounding processes, the many
separate steps involved, and the irregular
batch-type operation make release estimation
a difficult task. When direct measurement
data are not available, emission factors and
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mass balances, supplemented by engineering
assumptions, must be used. Mass balance
estimates are most effective for chemicals
that are "otherwise used," such as catalysts,
solvents, acids, and bases. Because these
chemicals do not become part of the product,
the quantity used is equal to the quantify
released as waste before treatment. Engi-
neering assumptions can then be used to
determine into which media the chemical is
released (air, wastewater, or solid waste).
Caution should be exercised when using the
mass balance technique to estimate chemical
releases when the raw material input and
product output streams are large, as small
errors in purchasing and production data can
lead to large errors in release estimates.
The mass balance estimation technique is
quite applicable to rubber compounding
operations because of the precision required
when weighing out additives for the rubber
recipe. Given detailed information on chemi-
cal Inputs and knowledge of the quantity of
chemical retained in the product and chemi-
cally transformed during processing, one can
calculate chemical releases by determining
the difference.
Toxic Releases Via Wastewater
Ideally, the wastewater streams will be
combined into a single effluent stream for
which measurements of flow and concen-
trations are available. Some monitoring
information may be available from waste-
water discharge permits and in-house
sampling studies. Wastewater flows and
release parameters such as biochemical
oxygen demand, chemical oxygen demand,
suspended solids, etc., will be summarized on
your discharge permit; however, concen-
trations for specific listed compounds may
not be available.
When direct measurement information is
unavailable, an alternative estimation tech-
nique must be used. For "otherwise used"
compounds with extremely low vapor pres-
sures (for example, metal catalysts), you may
assume that all of the chemical used is
released in wastewater. If wastewater treat-
ment is used, a portion of these compounds
will be transferred to the wastewater sludge
or biodegraded, whereas the remainder will
be discharged with the wastewater.
Example: Using a mass balance to
estimate releases of cobalt compounds
from a cobalt-based catalyst.
In 1987, a synthetic rubber production
facility produced 80,000 pounds of
polybutadiene. A homogeneous cobalt-
based catalyst was used in the reaction
process. Samples of the rubber product
contained 170 ppm of cobalt. Purchasing
and inventory records indicate that 64,000
pounds ofCoCl2 catalyst was processed.
Assuming that the catalyst is the only
source of cobalt in the process and that all
equipment-cleaning wastes are washed
into the facility's sewers, the quantity of
cobalt released can be estimated by mass
balance. The quantity of cobalt lost as
waste is calculated as follows:
Amount of cobalt entering process =
64,000 lbCoCl2x
59 Ib Co/130 Ib CoCl2
= 29,046 Ib
Amount of cobalt in product =
80,000 tons polybutadiene x
2,000 Ib/ton x
170 Ib cobalt/1,000,000 Ib
polybutadiene
= 27,200 Ib
Amount of cobalt lost as waste =
29,046 Ib (entering process) -
27,200 Ib (in product)
= l,846lb
It can be assumed that the 1,846
pounds of cobalt was lost through
equipment washdowns. If untreated
wastewater from the facility was
discharged to a publicly owned treatment
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works (POTW), the facility could report that
1,900 pounds of cobalt was "transferred to
POTW." If pretreatment was provided on
site and a wastewater sludge was
generated, estimates of the quantity of
cobalt released as solid waste would also
have to be considered.
The problems inherent with the use of
mass balances for large processes are
evident if you assume that the quantity of
cobalt found in the poly butadiene product
was 200 ppm rather than 170 ppm. At
200 ppm, the quantity of cobalt leaving as
product would be 32,000 pounds, which
exceeds the quantity of cobalt entering the
process. Thus, a small analytical error in
the product stream could cause a large
error in the release estimation.
Toxic Releases to Air
Atmospheric emissions data may be
available from process monitoring informa-
tion (vent flows and concentrations), air
operating permits, or the technical literature.
Most of the information available on air emis-
sions will be in the form of total VOC and
particulate emissions. Engineering calcu-
lations and assumptions can often be used to
convert this type of information into releases
of specific toxic compounds. If mass balance
calculations are used, you can assume that
any releases of extremely volatile compounds
(such as butadiene) will be to the
atmosphere.
'Example: Using an emission factor to
estimate atmospheric releases from a
monomer recovery process.
A monomer plant produces 40,000 tons
of crumb emulsion latex per year. Emis-
sion measurement data are not available,
and an accurate mass balance calculation
is difficult to perform because of the large
input and output streams. According to
ERA'S Compilation of Air Pollutant Emis-
sion Factors, total volatile organic
emissions are approximately 5.2 pounds
per ton of latex produced. An occupational
monitoring program at this plant indicated
that butadiene concentrations in the
ambient air were typically 9 times greater
than styrene concentrations. Because
butadiene and styrene will make up the
vast majority of the VOC emissions, it can
be assumed that total butadiene and
styrene air releases are 5.2 pounds per ton
of latex. Based on the 9-to-l ratio of
butadiene to styrene, process releases can
be calculated as follows:
Amount of 1,3-butadiene released =
40,000 tons latex x
5.2 Ib volatiles/1 ton latex x 90%
= 187,200 Ib
Amount of styrene released =
40,000 tons latex x
(5.2 Ib volatiles/1 ton latex) x 10%
= 20,800 Ib
These releases are sent to ajlare
before being discharged to the atmosphere.
Based on the manufacturer's experience
and test data, the flare destruction
efficiency is assumed to be 90 percent.
Thus, the plant in this example could
report annual releases of 19,000 pounds
of 1,3-butadiene and 2,100 pounds of
styrene.
Air releases from rubber compounding
operations, which are typically in the form of
particulates, are often controlled by fabric
filters. If the fabric filter efficiency and quan-
tity of particulate captured are known or can
be estimated, air releases can be calculated.
The specific chemical composition of the
fabric filter dusts can then be used to esti-
mate air releases of toxic chemicals.
Toxic Releases Via Solid Waste
In general, only direct measurement and
mass balance techniques are useful for esti-
mating toxic chemical releases in wastewater
treatment sludge. Direct measurement data
for wastewater sludge are 6ften required
before disposal will be approved. If direct
measurement data are used to estimate
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wastewater releases, you may find a mass
balance estimation technique useful for
estimating releases via wastewater sludge.
Estimating solid wastes generated from
rubber compounding operations usually
requires mass balances and/or engineering
calculations. For example, If the quantity of
scrap rubber discarded and the concentration
of a toxic constituent in the rubber product
are known, multiplying these values will yield
an estimate of the release of the constituent
in the scrap (solid waste). The key to this
approach is knowing the concentrations of
toxic chemicals In the rubber product.
Example: Estimating zinc releases in
solid wastes from a rubber
compounding operation.
Based on the recipes used, a rubber
compounder knows the concentration of
zinc oxide in a particular rubber mixture is
2.5 percent by weight. Production records
indicate that 2,000 tons of this rubber
mixture was manufactured in 1987.
Purchasing and inventory records indicate
that 105,000 pounds of zinc oxide was
processed during the year. The quantity of
zinc oxide (and thus zinc) lost as solid
waste can be calculated by mass balance
asfottows:
Amount ofZnO in product =
2,000 tons rubber product x
2,000 Ib/tonx
0.025 Ib ZnO/1 tb product
-100,000 Ib
Amount of ZnO in solid waste =
105,000 Ib ZnO (processed) -
100,000 Ib ZnO (in product)
- 5,000 Ib
Amount of zinc in waste =
5,000 Ib ZnO x
O.SlbZn/l'lbZnO
= 4,000 Ib
It may be assumed that all of the zinc lost
through cleanups, scrap rubber, and fabric
filter participate (assuming the fabric filter
capture efficiency is high) is released as
solid waste.
Other Toxic Releases
Other wastes in the rubber production
and compounding industry from which toxic
chemicals may be released include:
• Residues from pollution control
devices
• Wash water from equipment
cleaning
• Product rejects
• Used equipment
• Empty chemical containers
Releases from these sources may already
have been accounted for, depending on the
release estimation methods used. These
items (and any other of a similar nature)
should be included in your development of a
process flow diagram.
The contribution of sources of wastes
such as cleaning out vessels or discarding
containers should be small compared with
process losses. If you do not have data on
such sources (or any monitoring data on
overall water releases), assume up to 1 per-
cent of vessel content may be lost duririg
each cleaning occurrence. For example, if
you discard (to landfill) "empty" drums that
have not been cleaned, calculate the release
as 1 percent of normal drum content. If the
drums are washed before disposal, this may
contribute 1 percent of the content to your
wastewater loading.
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Step Five
Complete the Toxic Chemical Release
Inventory Reporting Form.
After estimating the quantity of each
chemical released via wastewater, solid
waste, and air emissions, you must deter-
mine the amount of each chemical released to
water, land, or air or transferred to an offsite
disposal facility. This determination will be
based on the disposal method you use for
each of your waste streams. Enter the re-
lease estimates for each chemical or chemical
category in Part III of the Toxic Chemical
Release Inventory Reporting Form. Also enter
the code for each treatment method used, the
weight percent by which the treatment
reduces the chemical in the treated waste
stream, and the concentration of the chemi-
cal in the influent to treatment (see instruc-
tions). Report treatment methods that do not
affect the chemical by entering "0" for
removal efficiency.
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For More Information
Emergency Planning
and Community
Right-to-Know
Hotline
Small Business
Ombudsman
Hotline
(800) 535-0202
or
(202) 479-2449
(in Washington, D.C.
and Alaska)
(800) 368-5888
or
(703) 557-1938
(in Washington, D.C.
and Virginia)
The EPA brochure, Title III Section 313
Release Reporting Requirements (EPA 560/4-
87-001) presents an overview of the new law.
It Identifies the types of facilities that come
under the provisions of Section 313, the
threshold chemical volumes that trigger re-
porting requirements, and what must be
reported. It also contains a complete listing
of the chemicals and chemical categories
subject to Section 313 reporting. The EPA
publication, Estimating Releases and Waste-
Treatment Efficiencies for the Toxic Chemical
Release Inventory Form (EPA 560/4-88-002),
presents more detailed information on gen-
eral release estimation techniques than is
included in this document.
Additional Sources of Information
on Releases From Rubber
Production and Compounding
U.S. Environmental Protection Agency.
Source Assessment: Rubber Processing
State-of-the-Art. EPA-600/2-78-004. PB
281423/4. Cincinnati, Ohio. March 1978.
U.S. Environmental Protection Agency. The
Rubber Processing Chemicals Data Base.
EPA-600/2-84-030. January 1984.
U.S. Environmental Protection Agency.
Compilation of Air Pollutant Emission Fac-
tors, Fourth Edition. AP-42. Research
Triangle Park, North Carolina. September
1985.
U.S. Environmental Protection Agency.
Industrial Process Profile for Environmental
Use. Chapter 9: The Synthetic Rubber
Industry. EPA-600/2-77-023. Cincinnati,
Ohio. February 1977.
10
*U.S. Government Printing Office : 1988 - 516-002/80179'
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