United States
Environmental Protection
Agency
National Risk Management
Research Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-96/136
December 1996
&EPA Project Summary
Addendum to Assessment of
Styrene Emission Controls for
FRP/C and Boat Building
Industries
Emery J. Kong, Mark A. Bahner, and Sonji L. Turner
This report is an addendum to a 1996
EPA report, Assessment of Styrene
Emission Controls for FRP/C and Boat
Building Industries. This addendum pre-
sents additional evaluation of the bio-
logical treatment of styrene emissions,
Dow Chemical Company's Sorbathene
solvent vapor recovery system, Occu-
pational Safety and Health Administra-
tion regulations and other policies that
affect the fiber reinforced plastics/com-
posites (FRP/C) and boat building in-
dustries, and secondary pollution and
natural gas usage resulting from vari-
ous emission control options.
This Project Summary was developed
by the National Risk Management Re-
search Laboratory's Air Pollution Pre-
vention and Control Division, Research
Triangle Park, NC, to announce key
findings of the research project that is
fully documented in a separate report
of the same title (see Project Report
ordering information at back).
Introduction
In 1995 and 1996, Research Triangle
Institute (RTI), under contract to the U.S.
Environmental Protection Agency's
(EPA's) Office of Research and Develop-
ment, investigated end-of-pipe controls to
reduce styrene emissions from the fiber-
reinforced plastics/composites (FRP/C)
and boat building industries. The types of
controls that were evaluated included ther-
mal oxidation (also called incineration),
catalytic oxidation, biofiltration, and
preconcentration/oxidation systems. In
preconcentration/oxidation systems, sty-
rene is typically adsorbed onto materials
such as activated carbon, zeolite, and
proprietary polymers, then desorbed (in a
concentrated stream) for catalytic oxida-
tion. Preconcentration/oxidation allows the
oxidizer to run nearly autothermally (with-
out additional fuel), even for the low sty-
rene inlet concentrations typically found in
the FRP/C and boat building industries.
The results of RTI's research were pub-
lished in a 1996 EPA report, Assessment
of Styrene Emission Controls for FRP/C
and Boat Building Industries.
Objectives
Subsequent to completion of the origi-
nal report, several additional issues re-
garding end-of-pipe controls for styrene
were identified. The goals of this project
were to address four additional issues:
1)Recently, studies on biofiltration/
bioscrubbing of styrene have been
identified that were not discussed in
the original EPA report. The EPA re-
quested further in-depth investigation
of these studies.
2)The EPA also identified Dow
Chemical's Sorbathene vapor recov-
ery system as a possible styrene re-
moval technology, and requested an
evaluation of the Sorbathene process
for removal of styrene emitted from
FRP/C and boat building facilities.
3)The EPA requested further documen-
tation and interpretation of Occupa-
tional Safety and Health Administra-
tion (OSHA) regulations that can af-
fect the viability of end-of-pipe con-
trols for styrene removal. The original
report contained cost calculations that
showed that, for a given styrene mass
input to a control device, cost can be
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substantially reduced if concentration
to the control device can be increased
(i.e., if air flow rate can be reduced).
The EPA requested exploration of is-
sues including operating spray booths
above the allowable Permissible Ex-
posure Limit (PEL) for styrene, with
respirators being worn by the opera-
tors, and fresh air supplied to the
operators in a "space suit."
4) In May 1996, a report containing cal-
culations of the noneconomic impacts
of incineration was prepared by Rob-
ert Haberlein (a consultant) for the
Society of the Plastics Industry/Com-
posites Institute (SPI/CI), a trade or-
ganization for the FRP/C industry.
Noneconomic impacts, including en-
ergy usage and the generation of sec-
ondary pollutants (e.g., nitrogen ox-
ides, sulfur dioxide, and carbon diox-
ide), were calculated, assuming ther-
mal oxidation of an exhaust stream
containing 20 parts per million (ppm)
of styrene. The EPA requested an
analysis of the assumptions in the
report, and calculation of noneconomic
impacts for other types of controls
(such as preconcentration/catalytic
oxidation).
Analyses and Results
RTI's further investigation of biofiltration/
bioscrubbing included contacts with six
biofiltration/bioscrubbing researchers and
suppliers. Four researchers/suppliers pro-
vided information, including data on flow
rates, emission sources, concentrations,
control efficiencies, frequency of regen-
eration, and costs (capital and operating).
Most of the installations that were identi-
fied were bench- or pilot-scale, with flow
rates of less than 1,700 m3/h (1,000 cfm).
The largest system controlling styrene was
a bioscrubber, operating on an automo-
tive parts plant in Germany, with a flow
rate of 20,000 m3/h (11,774 cfm). The
system capital costs for this application
were given as $450,000 to $700,000. This
can be compared to an estimated equip-
ment cost and total capital investment of
$301,000 and $619,000, respectively, from
the biofiltration cost spreadsheet devel-
oped in the original styrene controls as-
sessment. Most of the biofiltration sys-
tems were able to achieve a control effi-
ciency of 90% or greater, except during
acclimation periods (periods after pro-
longed shutdown), or process upsets.
Dow Chemical Company's Sorbathene
process was evaluated as a means of
controlling styrene emissions from FRP/C
and boat building operations. The
Sorbathene process is typically applied to
recover organic vapors from process vents,
storage tanks, and loading/unloading op-
erations. The process can be designed to
achieve 99.9% removal from vent streams
ranging in flow rate from 34 to 5,100 m3/h
(20 to 3,000 cfm), with volatile organic
compound feed concentrations between
1,000 and 500,000 ppm. RTI's investiga-
tion indicated that the Sorbathene pro-
cess would not be economically feasible
for the large flow rates and low styrene
concentrations typically associated with
FRP/C fabrication and boat building.
The principal OSHA regulations affect-
ing the design and economics of end-of-
pipe controls in the FRP/C industry deal
with allowable employee exposure to sty-
rene. Various organizations in the rein-
forced plastics industry voluntarily com-
mitted to meeting a 50-ppm 8-hr time-
weighted average (TWA) concentration in
July 1997. OSHA regulations require that
administrative or engineering controls (e.g.,
enclosure or confinement of the opera-
tion, general and local ventilation, and sub-
stitution of less toxic materials) must be
considered and implemented, if feasible.
If these controls are determined to be
infeasible, or while these controls are be-
ing implemented, respiratory protection is
required. RTI identified one boat building
facility operating a paint booth where
"space suits" with fresh air supply are
used to protect spray gun operators.
Calculations of the noneconomic (en-
ergy and environmental) impacts of incin-
eration were presented in a May 1996
report for the SPI/CI. These calculations
were based on incineration (thermal oxi-
dation) of an exhaust stream with a sty-
rene concentration of 20 ppm. RTI's in-
vestigation indicated that a styrene con-
centration of 20 ppm would be uncharac-
teristically low for an FRP/C facility per-
forming open mold spraying, and with an-
nual polyester resin usage greater than
900 Mg (1000 tons, corresponding to a
medium-to-large plant). Further, RTI's pre-
vious economic analysis indicated that
preconcentration/catalytic oxidation sys-
tems have lower annualized costs than
straight thermal oxidation, for styrene inlet
concentrations below approximately 300
ppm. Therefore, it would be unlikely that a
FRP/C company would choose a thermal
oxidizer for an exhaust stream containing
20 ppm of styrene.
RTI conducted noneconomic impact
analyses for three types of control de-
vices (thermal oxidizer, catalytic oxidizer,
and preconcentrator/catalytic oxidizer),
over styrene inlet concentrations ranging
from 20 to 260 ppm (the highest known
exhaust concentration for any existing fa-
cility with spraying operations). It was found
that natural gas usage and secondary pol-
lutant generation were much lower for
preconcentration/oxidation systems than
for straight thermal oxidation. Since
preconcentration/oxidation systems also
appear to have lower annualized costs
than straight thermal oxidation (below ap-
proximately 300 ppm), the choice of
preconcentration/oxidation systems in this
range reduces both economic and non-
economic impacts.
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E.J. Kong, M.A. Bahner, and S.L Turner are with Research Triangle Institute,
Research Triangle Park, NC 27709.
Norman Kaplan is the EPA Project Officer (see below).
The complete report, entitled "Addendum to Assessment of Styrene Emisssion
Controls for FRP/C and Boat Building Industries," (Order No. PB97-121156;
Cost: $21.50, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air Pollution Prevention and Control Division
National Risk Management Research Laboratory
U. S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection Agency
Center for Environmental Research Information (G-72)
Cincinnati, OH 45268
Official Business
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EPA/600/SR-96/136
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