United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-94/126 November 1994
EPA Project Summary
Evaluation of Containment and
Control Options for Methyl
Bromide in Commodity
Treatment
Glenn B. DeWolf and Matthew R. Harrison
Methyl bromide (MeBr) is an ozone-
depleting chemical scheduled to be
phased out by The Clean Air Act by the
year 2001. For agricultural commodity
fumigation, there is no ready substi-
tute for MeBr. This study was under-
taken to investigate means for MeBr
recovery, reuse, and destruction to pre-
vent atmospheric emissions if its lim-
ited use were still allowed.
Approximately 4-5 million Ib/yr
(1.8 - 2.3 million kg/yr) of MeBr is
used for commodity/agricultural
harvest fumigation. Commodity fu-
migation is carried out extensively at a
few locations, mostly major seaports.
Fumigation is conducted in chambers
built for holding the commodity during
fumigation and in temporary enclosure,
such as under tarpaulins and in ve-
hicles. The emissions are vented to the
atmosphere.
Few control systems exist for MeBr
emissions. Likewise, control system
research and development has been
limited. Vendors have proposed con-
trol technologies for MeBr control, re-
covery, and recycle, but few systems
have been built. Conventional vapor
control technologies, such as activated
carbon adsorption systems, appear to
be applicable to MeBr emissions. These
systems must also provide for recov-
ery. Control will probably be expensive
due to the small volumes of recover-
able material and the intermittent na-
ture of fumigation operations.
This Project Summary was developed
by EPA's Air and Energy Engineering
Research Laboratory, Research Tri-
angle Park, NC, to announce key find-
ings of the research project that is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
Methyl bromide (MeBr), with the
chemical formula CH3Br, also called
bromomethane, is listed by the 1991
Montreal Protocol as an ozone deplet-
ing chemical similar to the other haloge-
nated hydrocarbons such as the
chlorofluorocarbons (CFCs). The U.S.
Environmental Protection Agency's (EPA's)
regulations authorized by the Clean Air
Act (CAA) call for a phaseout of MeBr
production by the year 2001. This would
mean an end to uses of MeBr where the
material is emitted to the atmosphere since
no future supply of MeBr would be avail-
able. In some applications, there is no
apparent, ready substitute for MeBr. There-
fore, this study was undertaken to investi-
gate possible means for MeBr recovery
for reuse and for MeBr destruction to pre-
vent atmospheric emissions if its limited
use were still allowed.
MeBr is widely used in U.S. agriculture
as a fumigant. A fumigant is a material
that can exist as a gas in a concentration
lethal to a pest organism. As a gas, it can
penetrate the material being fumigated,
and then diffuse away after the fumigation
ends. MeBr is a very useful general fumi-
gant since it is a permeating gas at ambi-
ent temperatures and pressures and since
it has a very desirable toxicity to many
pest populations.
Table 1 shows that the primary use of
MeBr is in soil fumigation, where it is used
to kill nematodes and soil insects prior to
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Table 1. Methyl Bromide Use [million Ib/yr (million kg/yr)]
1991 Use from CPS
1990 Use from NAPIAP
Total
Soil Fumigation
Chemical Intermediate
Structural Space Fumigation
Commodity Space Fumigation
47
35
3.8
3.8
3.8
(21)
(16)
(1.7)
(1.7)
(1.7)
64
47
4 to 9
5
(29)
(21)
(1.8 to 4.1)
(2.3)
planting. According to Chemical Products
Synopsis (CPS), approximately 75% of
the 47 million Ib (21 million kg) of MeBr
consumed in 1991 in the U.S. was for this
application. An additional 8% of MeBr con-
sumption is as a chemical intermediate or
as a solvent. The remaining 16% of MeBr
consumption is used in space fumigation.
Half of that space fumigation is structural
fumigation, and half is for commodity fu-
migation.
The National Agricultural Pesticide Im-
pact Assessment Program (NAPIAP) of
the U.S. Department of Agriculture (USDA)
has produced use numbers for MeBr that
are different from the CPS numbers. How-
ever, both sources show that approxi-
mately 4-5 million Ib/yr (1.8 - 2.3 million
kg/yr) of MeBr is used for commodity/
agricultural harvest space fumigation.
This study has gathered preliminary data
that can be used to determine if some of
the essential agricultural commodity fumi-
gation applications of MeBr could be con-
tinued by the use of some emission control
methods on those commodity fumigation
applications.
Conclusions
MeBr Uses and Quantities
Since MeBr uses are relatively restricted,
MeBr can be viewed as a specialty fumi-
gant. The consumption of MeBr for space
fumigation of commodities represents
about 8% of MeBr use. The primary use
for MeBr in commodity fumigation is for
fruits and nuts. In the treatment of these
commodities, there are general commod-
ity containment schemes that are com-
mon throughout the industry, although
some details may vary with individual in-
stallations. The types of configurations for
commodity containment are relatively lim-
ited.
Fumigation is carried out extensively at
a few primary locations, mostly major sea-
ports. Two of the largest ports where MeBr
is used are San Diego and Philadelphia.
Other major ports include Seattle and Mi-
ami, but any port where fruit and nuts are
imported is a candidate. Also, fumigation
facilities are reported to be present at
some airports and military facilities.
Emission Source
Characteristics
Emissions sources are characterized in
terms of physical configuration and emis-
sion stream characteristics.
Physical configurations are divided into
two categories: (1) sources with a duct,
pipe, or stack outlet, and (2) sources with
multiple, irregular outlets. The former oc-
cur in chambers specifically built for hold-
ing the commodity during fumigation. The
latter occur with tarpaulin fumigation or
fumigation in vehicles where ordinary leak-
age or simply an open door is used to
vent the MeBr when fumigation is com-
plete.
The emissions arise when air is blown
through the commodity to remove the
MeBr. Currently the emissions are vented
directly to the atmosphere.
Little data are currently available for
stream characteristics. Information that is
available suggests flow rates in the range
of no more than a few thousand to a few
tens of thousand of cubic feet per minute
air flow with a MeBr content ranging from
a few hundred to a few thousand parts
per million.
Currently few control systems exist for
MeBr emissions. Likewise, research and
development related to control system de-
sign has been extremely limited.
Various vendors have proposed control
technologies for MeBr control, recovery,
and recycle. Few systems have been built.
Currently, systems are being investigated
and the Port of San Diego is installing a
MeBr treatment system. Some systems
have been installed overseas. Technical
details of these systems are not readily
available, so that further work would be
required to determine how extensively they
control emissions and how effective they
may be at recovery.
In general, conventional vapor control
technologies, such as activated carbon
adsorption systems, appear to be appli-
cable to MeBr emissions. However, in the
context of minimum or even zero emis-
sions, depending on the regulatory sce-
nario, control systems must also provide
for recovery. Conventional approaches
using condensation and other methods
appear to be applicable here. The funda-
mental technologies required appear to
exist, but the specifics of the application
of these technologies to the MeBr control
issue require much more investigation and
design data acquisition.
Process Economics
Process economics of MeBr control and
recovery are not well defined. Scattered
data on actual and possible costs of sys-
tems were skimpy. Because many com-
ponents of a control system would appear
to rely on existing technologies, costs and
the corresponding economics do not ap-
pear to be difficult to estimate. Costs can
be expected to be comparable to those of
other vapor control systems for similar
gas stream flow rates.
Preliminary economics of a conceptual
design prepared specifically for this report
indicate that control will be relatively ex-
pensive. The relative expense compared
with control systems of similar nature in
other applications is based on relatively
small volumes of recoverable material that
would be handled and the intermittent na-
ture of many of the fumigation operations
to which the control system would be ap-
plied. At this time, sufficient data are not
available for either design or costs to make
a definitive statement.
A factor that might considerably influ-
ence the economics of MeBr control is the
availability of future MeBr supplies. This
will be influenced by the regulatory sce-
nario. A total ban, but allowance of the
use of existing MeBr inventories with re-
cycle would, in effect, make recycle im-
practical for technical reasons. Chemical
reaction losses would quickly deplete the
supply. On the other hand, a selective
ban that would allow some manufacture
of MeBr to continue might drive up the
price, assuming a manufacturer were will-
ing to continue manufacture, because the
use volume would be sharply reduced.
Unit manufacturing costs would increase
sharply.
Current Research and
Development Activities
Current research and development ac-
tivities appear to be underway in several
quarters on the very issues discussed in
this report. These activities do appear to
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be limited at the present time, however.
Much of the current work appears to be
under the auspices of various vendors of
systems and equipment. Some govern-
ment agencies and industrial groups are
showing increasing interest in funding
some research. The United Nations Envi-
ronment Programme (UNEP) has had a
leading role in addressing some of these
issues.
Information Gaps
In general, information is lacking in two
fundamental categories: (1) MeBr emis-
sion source characterization and (2) con-
trol technology characterization. The
fundamental focus needs to shift beyond
mere reduction of emissions and toward
recovery and recycle. There also needs to
be an effort to gather some fundamental
performance data related specifically to
fundamental stream characteristics. This
is especially important because of the re-
ported potential for the accumulation of
various commodity chemical components
picked up by the MeBr on each cycle of
contact with the commodity being fumi-
gated. Detailed economic evaluations
based on existing data should be carried
out early in order to better direct the re-
search and maximize research efficiency.
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G. DeWolfand M. Harrison are with Radian Corp., Austin, TX 78720-1088.
Robert V. Hendriks is the EPA Project Officer (see below).
The complete report, entitled "Evaluation of Containment and Control Options for
Methyl Bromide in Commodity Treatment," (Order No. PB94-195070; Cost:
$27.00, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
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EPA/600/SR-94/126
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