United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
EPA-450/3-89-007
March 1989
Air
Alternative Control
Technology Document -
Ethylene Oxide
Sterilization/Fumigation
Operations
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EPA-450/3-89-007
Alternative Control
Technology Document -
Ethylene Oxide
Sterilization/Fumigation
Operations
Emissions Standards Division
U.S. Environmental Protection Agency
Region 5, Library (PL-12J)
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
March 1989
-------
This report has been reviewed by the Emission Standards Division of the
Office of Air Quality Planning and Standards, EPA, and approved for
publication. Mention of trade names or commercial products is not
intended to constitute endorsement or recommendation for use. Copies of
this report are available through the Library Services Office (MD-35),
U. S. Environmental Protection Agency, Research Triangle Park, N.C.
27711, or from National Technical Information Services, 5285 Port Royal
Road, Springfield, Virginia 22161.
n
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TABLE OF CONTENTS
Page
LIST OF FIGURES v
LIST OF TABLES vi
CHAPTER 1. INTRODUCTION !_1
CHAPTER 2. SUMMARY 2-1
CHAPTER 3. ETHYLENE OXIDE STERILIZATION/FUMIGATION PROCESSES AND
EMISSIONS 3_!
3.1 BACKGROUND INFORMATION "* 3.1
3.2 PROCESS DESCRIPTION '* 3.3
3.2.1 Bulk Sterilization 3,3
3.2.2 Single-Item Sterilization System 3.14
3.2.3 Beehive Fumigators 3_15
3.3 EMISSION SOURCES 3_15
3.3.1 Sterilization Chamber Vents 3_i;
3.3.2 Sterilization Chamber Vacuum Pump Drains... 3-17
3.3.3 Aeration Room Vent 3_17
3.3.4 Equipment Leaks ! 3_17
3.3.5 Storage and Handling ".... 3.19
3.4 EMISSION ESTIMATES .' 3.19
3.4.1 Commercial Sterilization Facilities..!!.*.*!! 3-19
3.4.2 Hospitals 3_2i
3.5 CURRENT REGULATIONS ! 3.22
3.5.1 Occupational Safety and Health Administra- 3-22
tion Standards
3.5.2 State Regulations "" 3.22
3.6 REFERENCES FOR CHAPTER 3 !!!.*."! 3_25
CHAPTER 4. EMISSION CONTROL TECHNIQUES 4_i
4.1 BULK STERILIZATION PROCESSES 4.!
4.1.1 Sterilization Chamber Vent Emissions ! 4-1
4.1.2 Sterilization Chamber Vacuum Pump Drain
Emissions 4_15
4.1.3 Aeration Room Vent Emissions !!!!* 4.16
4.2 OTHER STERILIZATION PROCESSES 4_22
4.2.1 Single-item Sterilization ! 4.22
4.2.2 Fumigation with Portable Units * 4-22
4.3 ALTERNATIVES TO EO STERILIZATION " 4_22
4.4 RETROFIT CONSIDERATIONS 4 23
4.5 IMPACTS OF A CFC REGULATION ON EO EMISSION
CONTROLS 4 73
4.6 REFERENCES FOR CHAPTER 4 ! 4 24
111
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TABLE OF CONTENTS (continued)
CHAPTER 5. EMISSION CONTROL COSTS ................................. 5_1
5.1
5.2
5.3
5.4
5.5
5.6
INTRODUCTION ................................
CONTROL COSTS FOR COMMERCIAL STERILIZATION
FACILITIES
5.2.1 Description of Components Costed
5.2.2 General Assumptions ............ ,
5.2.3 Capital Costs ..................
5.2.4 Annual ized Costs ...............
CONTROL COSTS FOR HOSPITAL STERILIZATION
CHAMBERS .............................. .....
CONTROL COSTS FOR OTHER STERILIZATION SYSTEMS
CONTROL COSTS FOR AERATION ROOMS .......
REFERENCES FOR CHAPTER 5
5_1
5_1
5-1
5.2
5_3
5.3
5.3
5-3
5.4
5-14
APPENDIX A. FEDERAL AGENCY CONTACTS, CONTROL DEVICE VENDORS, AND
ETHYLENE GLYCOL RECOVERY COMPANIES
APPENDIX B. COST INDICES AND SAMPLE COST CALCULATIONS
APPENDIX C. CONTROL DEVICE COSTS (CATALYTIC OXIDATION AND GAS/
SOLID REACTOR SYSTEM)
iv
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LIST OF FIGURES
Page
Figure 3-1. Schematic of a gas sterilizer 3_5
Figure 3-2. Sterilization cycle for 12/88 3_H
Figure 3-3. Sterilization cycle for pure EO 3-12
Figure 3-4. Schematic of emission sources at commercial
sterilization facilities 3_16
Figure 3-5. Hydrolysis rates of dilute, neutral aqueous solutions
of ethylene oxide 3_18
Figure 4-1. Countercurrent packed bed scrubbing system 4-5
Figure 4-2. Detoxification tower control system 4.7
Figure 4-3. Catalytic oxidation system 4-11
Figure 4-4. Condensation/reclamation system 4-13
Figure 4-5a. Once-through liquid-ring vacuum pump 4-17
Figure 4-5b. Recirculating liquid-ring vacuum pump 4.17
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LIST OF TABLES
Page
TABLE 2-1. CONTROL COSTS FOR ACID HYDROLYSIS AT COMMERCIAL
STERILIZATION FACILITIES 2-3
TABLE 3-1. LOCATIONS OF COMMERCIAL STERILIZATION FACILITIES—EPA
DATA BASE 3.2
TABLE 3-2. NUMBER OF FACILITIES AND STANDARD INDUSTRIAL
CLASSIFICATION (SIC) PER INDUSTRY CATEGORY-EPA
COMMERCIAL STERILIZATION DATA BASE 3.4
TABLE 3-3. CHAMBER SIZES—EPA COMMERCIAL STERILIZATION
DATA BASE 3_6
TABLE 3-4. PHYSICAL AND CHEMICAL PROPERTIES OF ETHYLENE OXIDE,
DICHLORODIFLUOROMETHANE, AND CARBON DIOXIDE 3-8
TABLE 3-5. STERILANT GAS TYPE USAGE-EPA COMMERCIAL
STERILIZATION DATA BASE 3.9
TABLE 3-6. AVERAGE EMISSIONS FOR COMMERCIAL STERILIZATION
FACILITIES—EPA DATA BASE 3_20
TABLE 3-7. AVERAGE EMISSIONS FROM HOSPITAL STERILIZERS 3-23
TABLE 3-8. STATE REGULATIONS FOR ETHYLENE OXIDE EMISSIONS 3-24
TABLE 4-1. ETHYLENE OXIDE EMISSION CONTROL DEVICES FOR
STERILIZATION CHAMBER VENTS—EPA COMMERCIAL
STERILIZATION DATA BASE 4_2
TABLE 5-1. CONTROL COSTS FOR ACID HYDROLYSIS 5.5
TABLE 5-2. COST OF DAMAS SCRUBBER MODELS (F.O.B.) 5.5
TABLE 5-3. INCREMENTAL CAPITAL COSTS OF MANIFOLDING
STERILIZATION CHAMBERS 5.7
TABLE 5-4. CAPITAL COST OF CHECK VALVE FOR CHAMBER 5.3
TABLE 5-5. MISCELLANEOUS OPERATING COSTS 5.9
TABLE 5-6. DATA USED TO CALCULATE CONTROL EQUIPMENT CAPITAL
COSTS 5_10
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LIST OF TABLES (continued)
Page
TABLE 5-7. DATA USED TO CALCULATE CONTROL DEVICE ANNUALIZED
COSTS 5_n
TABLE 5-8. HOSPITAL EMISSION CONTROL COSTS 5.43
TABLE A-l. CONTACTS AT FEDERAL AGENCIES A-l
TABLE A-2. CONTROL DEVICE MANUFACTURERS A-2
TABLE A-3. ETHYLENE 6LYCOL RECOVERY COMPANIES A-3
TABLE B-l. CAPITAL AND ANNUALIZED COSTS OF INSTALLING SCRUBBER.... B-6
TABLE C-l. CATALYTIC OXIDATION C-l
TABLE C-2. ACID-WATER SCRUBBER AND GAS/SOLID REACTOR SYSTEM C-2
vn
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1.0 INTRODUCTION
The Clean A1r Act (CAA) identified December 31, 1987, as the latest
date for attainment of the national ambient air quality standard (NAAQS)
for ozone. As of this writing, many areas of the country are not in
attainment with the ozone NAAQS. The U. S. Environmental Protection
Agency (EPA) has proposed to require States that have ozone nonattainment
areas to submit revised State implementation plans (SIP's) that describe
what steps will be taken to attain the standard (52 FR 45044, November 24,
1987).
Under the proposed rule (52 FR 45044), to demonstrate attainment of
the NAAQS for ozone, emissions of volatile organic compounds (VOC's) must
be reduced to a level that will produce ozone concentrations consistent
with NAAQS as demonstrated by atmospheric dispersion modeling. Once the
State has determined the VOC emission reduction required to meet the
NAAQS, it must identify and select control measures that will produce the
required reductions as expeditiously as practicable.
In 1985, EPA published a Federal Register notice titled "Assessment
of Ethylene Oxide as a Potentially Hazardous Air Pollutant." The
conclusion of that notice, based on the information available, was that
EPA intended to list ethylene oxide (EO) under Section 112 of the CAA if
emission standards were warranted. Therefore, a reduction in EO emissions
(which also is a VOC) contributes to attainment of the NAAQS for ozone and
reduces potential health risks from direct exposure to EO.
This report presents technical information that State and local
agencies can use to develop strategies for reducing VOC (i.e., EO)
emissions for sterilization/fumigation facilities. The information in
this document will allow planners to (1) identify available control
alternatives and (2) evaluate the VOC reduction and cost of implementing
controls.
This document provides information on sterilization/fumigation
processes, EO emissions, and emission reductions, and cost associated with
the application of control units. Section 2.0 presents a summary of the
findings of this study. Section 3.0 provides a description of
sterilization/fumigation facility operations and emission sources.
1-1
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Section 4.0 provides a description of alternative control techniques for
the reduction of ethylene oxide emissions. Section 5.0 presents a cost
analysis that includes a methodology for computing annualized equipment
and operating costs.
A list of contacts at various Federal agencies who are knowledgeable
about sterilization/fumigation processes is presented in Appendix A.
1-2
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2.0 SUMMARY
Ethylene oxide (EO) is used as a sterilant/fumigant in the production
of medical equipment supplies, in miscellaneous sterilization and
fumigation operations, and at hospitals. Available information indicates
that EO is used at over 200 commercial sterilization facilities in the
U.S. and at approximately 7,000 hospitals. These facilities use EO as a
sterilant for heat- or moisture-sensitive materials or as a fumigant to
control microorganisms or insects. A variety of materials are sterilized
or fumigated with EO, including medical equipment (e.g., syringes and
surgical gloves), spices, cosmetics, and Pharmaceuticals. These materials
may be sterilized at the facility that produces or uses the product or by
contract sterilizers (i.e., firms under contract to sterilize products
manufactured by other companies). Libraries and museums use EO to
fumigate books and other historical items. State departments of
agriculture control diseases of bees by fumigating beehives with EO.
Practically all of the EO used in sterilization/fumigation processes
is estimated to be emitted from three sources: (1) the sterilizer vent(s)
(i.e., the vent from the vacuum pump gas/liquid separator), (2) the vacuum
pump drain, and (3) the aeration room or chamber. Uncontrolled emissions
from these sources are assumed to be 50 percent, 45 percent, and 5 percent
of the EO use, respectively. The total amount of EO used by the
203 commercial sterilization facilities (i.e., not hospitals) represented
in the EPA sterilization data base is 2,270 Megagrams per year (Mg/yr)
(5 million Ib/yr). Estimated emissions from these 203 facilities are
760 Mg/yr (1.7 million Ib/yr) from sterilizer vents, 1,000 Mg/yr
(2.2 million Ib/yr) from vacuum pump drains, and 110 Mg/yr (0.25 million
Ib/yr) from aeration room vents. The sterilizer vent emissions are less
than 50 percent of the EO use because several of these 203 facilities
control EO emissions from the sterilizer vent. However, drain and
aeration room emissions at these facilities are assumed to be
uncontrolled. Based on approximately 80 responses to a 1986 information
request to Federal hospitals and information in the 1988 American Hospital
Association data base, EO use at hospitals is estimated to be
approximately 1,000 Mg/yr. Because the majority of hospitals do not use
2-1
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£0 emission controls, £0 emissions from hospitals are assumed to equal the
£0 use of approximately 1,000 Mg/yr.
Three primary techniques are applicable to the control of EO
emissions from sterilization/fumigation processes: acid hydroysis (i.e.,
acid-water scrubbers), oxidation, and a gas/solid reactor system that
chemically reacts EO and binds it to the solid reactor packing. Control
efficiencies for those techniques range from 98.0 percent to 99.0 percent
for sterilizer vent emissions. However, the control efficiencies of these
devices have not been demonstrated for the low EO concentrations from
aeration processes. Acid hydrolysis and thermal oxidation are applicable
to the control of sterilizer vent emissions from the larger sterilizers
(>2.8 m [100 ft3]) at commercial sterilization facilities. Several
hospitals use catalytic oxidation or scaled-down acid-water scrubbers to
control emissions from hospital sterilization chambers. Catalytic
oxidation and the gas/solid reactor system are used by several hospitals
and a few commercial sterilization facilities to control EO emissions from
aeration rooms or aeration chambers. Closed-loop recirculating fluid
vacuum pumps can virtually eliminate drain EO emissions by routing the
gaseous phase exiting the gas/liquid separator to the sterilizer emission
control device.
Federal regulations for stratospheric ozone-depleting
chlorofluorocarbons (CFC's) have been developed under EPA's Stratospheric
Ozone Protection Program (SOPP). The majority of commercial sterilization
facilities and almost all hospitals use a sterilant gas mixture known as
12/88, which is 12 weight percent EO and 88 weight percent
dichlorodifluorocarbon (CFC-12). The use of CFC's in sterilant gases is
one of the source categories subject to the CFC regulations. However, the
requirements of a CFC regulation would not affect the ability of a
sterilization facility to control EO emissions.
The cost of controlling EO emissions from sterilizer vents at three
of the commercial sterilization facilities represented in EPA's data base
are presented in Table 2-1. Acid hydrolysis was chosen as the basis for
the cost calculations because that control technique currently is
practiced at many commercial facilities and has been demonstrated at both
small and large commercial sterilization facilities. Detailed cost
2-2
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TABLE 2-1. CONTROL COSTS FOR ACID HYDROLYSIS AT COMMERCIAL
STERILIZATION FACILITIES4 b
Model
plant
Small d
Medium8
Large
Total
sterilizer
volume,
m3 (ft3)
2.8
(100)
28
(1,000)
168
(6,000)
Annual
EO use,
Mg
(lb/1,000)
0.18
(0.39)
3.9
(8.7)
109
(240)
Capital
costs, $
76,000
160,000
291,000
Annuali zed
costs, $
21,200
40,800
117,000
Annual emis-
sion reduc-
tion, Mg
(lb/l,000)c
0.17
(0.37)
3.7
(8.2)
102
(226)
These cost .estimates are not applicable to hospitals because the acid-
water scrubbers costed are not designed for the low flowrates from the
.vacuum pumps on hospital sterilizers.
DSee Chapter 5 and Appendix B for the methodology used to calculate these
control costs.
Calculated as (0.99)x(0.95)(EO use). Five percent of the EO use is
assumed to be retained in the product after sterilization and emitted
.from the aeration room, which is assumed to be uncontrolled.
°The small model plant has one chamber and uses 12/88 (EO/CFC-12).
Therefore, a model 100 scrubber (see Table 5-2) was chosen as the basis
for the calculations.
8The medium model plant has one chamber and uses 12/88 gas. Therefore, a
.model 400 scrubber was chosen as the basis for the calculation.
The large model plant has seven chambers and uses 100 percent EO. The
sum of the volumes of the two largest chambers is 2,000 ft . Therefore,
a model 500 scrubber (with explosion-proof valves) was chosen as the
basis for the calculations.
2-3
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estimates have not been developed for the control of EO emissions from
hospitals or aeration processes. However, preliminary control cost
estimates for hospitals have been developed by EPA's Office of Research
and Development (see Chapter 5). Also, the Office of Air Quality Planning
and Standards currently is developing control cost estimates for aeration
rooms, which should be available by June 1989. (See Appendix C for
preliminary aeration control costs.)
Possible alternatives to EO sterilization include radiation, chlorine
dioxide, gas plasma, hydrogen peroxide, ozone, X-ray (a new, developing
technology), deep freezing (museums and spice industry), and increased use
of disposable medical items in hospitals. However, none of these
alternatives can replace the use of EO in all applications.
2-4
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3. ETHYLENE OXIDE STERILIZATION/FUMIGATION PROCESSES AND
EMISSIONS
3.1 BACKGROUND INFORMATION
Ethylene oxide (EO) is used as a sterilant/fumigant in the production
of medical equipment supplies, in miscellaneous sterilization and fumiga-
tion operations, and at hospitals. Available information indicates that
EO is used at over 200 commercial sterilization facilities in the U.S. and
at approximately 7000 hospitals.1'3 These facilities use EO as a
sterilant for heat- or moisture-sensitive materials or as a fumigant to
control microorganisms or insects. A variety of materials are sterilized
or fumigated with EO, including medical equipment (e.g., syringes and
surgical gloves), spices, cosmetics, and Pharmaceuticals. These materials
may be sterilized at the facility that produces or uses the product or by
contract sterilizers (i.e., firms under contract to sterilize products
manufactured by other companies). Libraries and museums use EO to
fumigate books and other historical items. State departments of agricul-
ture control diseases of bees by fumigating beehives with EO.
Information about facilities that use EO as a sterilant/fumigant was
obtained from three sources: (1) a survey of medical equipment suppliers
conducted by the Health Industry Manufacturer's Association (HIMA) in
1985, (2) an information request submitted by EPA under Section 114 of the
Clean Air Act to miscellaneous sterilizers and fumigators (identified
during an extensive survey of potential users) in July 1986, and (3) an
information request in January 1986 to Federal hospitals and nine of the
largest non-Federal hospitals. A total of 203 commercial sterilization
facilities (i.e., not hospitals) responded to the HIMA survey and the July
1986 EPA information request. Data from these responses comprise the EPA
sterilization data base. Approximately 80 hospitals responded to the
January 1986 information request.
As shown in Table 3-1, the facilities represented in the EPA
commercial sterilization data base are located in 43 States and Puerto
Rico. These facilities were grouped by Standard Industrial Classification
(SIC) into the following categories:
3-1
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TABLE 3-1. LOCATIONS OF COMMERCIAL STERILIZATION FACILITIES—EPA
DATA BASE1'2
State
Arizona
California
Colorado
Connecticut
Delaware
Florida
Georgia
Illinois
Indiana
Iowa
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
No. of
facilities*1
3
21
3
6
2
5
4
8
4
3
5
9
8
6
2
Missouri
New Hampshire
New Jersey
New York
North Carolina
Ohio
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
Tennessee
Texas
Utah
Virginia
Washington
No. of
facilities*
5
2
18
14
7
2
10
14
2
3
3
11
2
5
2
Subtotal
89
Subtotal
100
The EPA data base includes one facility located in each of the following
States: Alabama, Alaska, Arkansas, Hawaii, Kentucky, Maine, Nebraska,
Nevada, New Mexico, North Dakota, Oregon, South Dakota, Wisconsin, West
Virginia.
Subtotal
Total No. of
facilities
14
203
JDoes not include hospitals.
3-2
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1. medical equipment suppliers;
2. Pharmaceuticals;
3. other health-related industries;
4. spice manufacturers;
5. contract sterilizers;
6. libraries, museums, and archives;
7. laboratories (research, testing, and animal breeding); and
8. State departments of agriculture.1*
Table 3-2 shows the number of facilities in the EPA commercial
sterilization data base for the eight categories listed above. Table 3-2
also shows the SIC codes represented by these industry categories.
3.2 PROCESS DESCRIPTION
There are two main types of EO sterilization processes: (1) bulk
sterilization and (2) single-item sterilization. These processes are
described below.
3.2.1 Bulk Sterilization
Bulk sterilization is the more commonly used EO sterilization
process; 98 percent of the commercial sterilization facilities represented
in the EPA data base use this process.1*2 The products to be sterilized
are placed in a sterilization chamber and are exposed to a sterilant gas
at a predetermined temperature, humidity level, and pressure. The
equipment, sterilant gases, and sterilization cycle used for bulk
sterilization processes are described below.
3.2.1.1 Equipment. A schematic of a gas sterilizer is shown in
Figure 3-1. The main components of the sterilizer are the chamber and
vacuum pump. Chambers used by commercial sterilization facilities
typically range in volume from 2.8 cubic meters (m3) (100 cubic feet
[ft3]) to 28 m3 (1,000 ft3).1'2 Table 3-3 presents size data for the
chambers in the EPA commercial sterilization data base. Sterilization
chambers at hospitals range from less than 0.3 to 2 m3 (10 to 70 ft3) but
are typically about 0.6 to 0.8 m3 (20 to 30 ft3).5
A vacuum pump is used to remove air from the chamber before
sterilization begins and to evacuate the sterilant gas after the
sterilization cycle is complete. Typically, a once-through, water-ring
vacuum pump is used. Oil-sealed vacuum pumps or vacuum pumps that use
3-3
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TABLE 3-2. NUMBER OF FACILITIES AND STANDARD INDUSTRIAL CLASSIFICATION
(SIC) PER INDUSTRY CATEGORY-ERA COMMERCIAL STERILIZATION DATA BASE'
Industry category
No. of
facilities3
SIC
Medical equipment suppliers
Pharmaceuticals
Other health-related industries
Spice manufacturers
Contract sterilizers
Libraries, museums, and archives
Laboratories (research, testing,
and animal breeding)
State departments of
agriculture
Total
64
40
25
25
17
13
11
3841, 3842
2834, 5122, 2831, 2833
3079, 3693, 5086, 2211,
2821, 2879, 3069, 3569,
3677, 3999
2099, 5149, 2034, 2035,
2046
7399, 7218, 8091
8411, 8231
0279, 7391, 8071, 8922,
7397
8 9641
203
aDoes not include hospitals.
3-4
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GAS LINE llQUIHEUGAS
FILTER 1O VAPORIZER
GAS
SOURCE
CO
I
01
CONTROI
PANEL
VACUUM PUMP
VAPOKI/ER
UOOR
Figure 3-1. Schematic of a gas sterilizer. (Courtesy of Union Carbide Corporation, Linde Division.)
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TABLE 3-3. CHAMBER SIZES—EPA COMMERCIAL STERILIZATION DATA BASE
1 2
Size range,
m* (ft*)
<1.4 (<50)
1.5-2.8
(51-100)
2.9-14
(101-500)
15-28
(501-1,000)
29-57
(1,001-2,000)
>58 (>2,001)
No. of
chambers* Percent
87 20
29 7
111 26
130 29
60 14
10 2
Cumulative
No. of chambers
87
116
227
357
417
427b
Cumulative,
percent
20
27
53
84
98
100
j*Does not include hospitals.
This number excludes four single-item sterilization units, one 55-gal
drum user, and two facilities that did not report a chamber size.
3-6
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recirculated water also are used. There are indications that some
commercial sterilization facilities and hospitals are converting from
once-through water-ring vacuum pumps to full sealant recovery vacuum pumps
in order to meet the 1 part per million by volume (1 ppmv) Occupational
Safety and Health Administration (OSHA) standard for EO and proposed State
regulations.6'7
3.2.1.2 Sterilant Gases. Ethylene oxide is an extremely effective
sterilant gas. The EO penetrates product packaging (e.g., cardboard
shipping box, plastic shrink wrap, paper box, and final product wrapping)
and destroys bacteria and viruses on the product. The product remains
sterile until use because bacteria and viruses cannot penetrate the
product wrapping.
The most widely used sterilant gas is a mixture of 12 percent by
weight EO and 88 percent by weight dichlorodifluoromethane (CFC-12),
referred to as 12/88. Two other commonly used sterilant gases are
(1) pure EO (i.e., 100 percent EO) and (2) a mixture of 10 percent by
weight EO and 90 percent by weight carbon dioxide (C02), referred to as
10/90. Other sterllant gas mixtures that are used include 20/80, 30/70,
and 80/20 (weight percents E0/C02).l»2 Gas mixtures that contain
20 percent or greater EO (by weight) are considered flammable. The 80/20
(E0/C02) mixture has the same flammability range as pure EO.12 Physical
and chemical properties of EO, CFC-12, and C02 are given in Table 3-4.
Table 3-5 shows the number of commercial sterilization facilities
represented in the EPA data base that use a particular gas type and the
amount of EO used for each gas type. Since many commercial sterilization
facilities operate more than one sterilization chamber, the gas usage
rates in Table 3-5 also are presented on a chamber basis.1'2
Seventy-five percent of the hospitals that responded to the 1986
information request use 12/88. The rest use pure EO in the form of
ampules or single-use cartridges. At hospitals, pure EO is generally used
only in very small (<0.3m3 [10ft3]) chambers.
The 12/88 mixture is the most popular sterilant gas for several
reasons. Unlike pure EO, 12/88 is nonflammable and nonexplosive.
Therefore, the use of 12/88 does not require explosion-proof rooms and
additional safety precautions that are necessary when pure EO is used.
3-7
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CO
oo
TABLE 3-4. PHYSICAL AND CHEMICAL PROPERTIES OF ETHYLENE OXIDE, DICHLORODIFLUOROMETHANE,
AND CARBON DIOXIDE8-"
Ethylene oxide
Other designations
Appearance
Chemical formula
Molecular weight
Vapor pressure at 20*C (68*F)
Boiling point at 101.3 kPa
(14.7 psi)
FlammabiIity Iimits in air
Water solubiIity
Heat of combustion, vapor at
25'C <77*F)
Threshold limit value (TLV)
8-h time weighted average (TWA)
1,2-epoxyethane, oxirane,
dimethylene oxide
Colorless liquid or gas
44.0
146.0 kPa (21.2 psia)
10.4'C (50.7'F)
Lower 3 percent by volume
Upper 80+ percent by volume9
Completely miscible
1.306 kJ/mol (12,760 Btu/lb)
I ppmv
01chIorod i fIuoromethane
CFC-12, refrigerant 12,
propel I ant 12
Colorless gas, readily liquified
under pressure and/or cooling
CC.2F2
120.9
567.6 kPa (82.3 psia)
-29.8*C (-21.6'F)
Nonflammable
Low solubiIity
111 kJ/mol (396 Btu/lb)
1,000 ppmv
Carbon dioxide
Carbonic acid gas,
carbonic anhydride
Colorless gas
co2
44.0
5,731.0 kPa (831 psia)
-78.5'C (-109.3'F)
Non fIammabIe
5,000 ppmv
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CO
I
TABLE 3-5. STERILANT GAS TYPE USAGE-ERA COMMERCIAL STERILIZATION DATA BASE1*2
No. of .
Sterllant gas facilities* b
12/88 (EO/CFC-12)
Pure EO
10/90 (E0/C02)
Other mixtures6
154
44
14
16
Percent of
facilities
76
22
7
8
No. of
chambers0
295
122
19
25
=SBS^==SSS=^==S=====
Percent of
chambers
68
28
4
6
EO use,
Mg/yr*
720
1,350
4
190
Percent of
total EO use
30
60
<0.01
10
K
bThere
these
"" "" ""•
» •••»•« "
Amount of EO in the sterllant gas mixture.
Includes mixtures of EO and C02 with a weight percent of EO ranging from 20 to 80 percent and custom
-------
The 10/90 mixture also is nonflammable and nonexplosive.12 But, because
10/90 is only 10 percent EO by volume whereas 12/88 is 27.3 percent EO by
volume, 10/90 requires higher operating pressures to obtain an EO
concentration that is sufficient for effective sterilization
(approximately 304 kilopascals [kPal, or 44 pounds per square inch
absolute (psial, for 10/90, as compared to 170 kPa [24.7 psial for
12/88). The chambers used for 10/90 sterilization must be ASME-rated
pressure vessels, (i.e., manufactured in accordance with Section VIII,
Division I, of the ASME Pressure Vessel Code) and are, therefore, more
expensive to construct than the chambers used with 12/88. However,
because of insurance requirements, many commercial sterilization
facilities use chambers that meet requirements for ASME-rated pressure
vessels when sterilizing with 12/88 or with explosive mixtures below
ambient pressure.
3.2.1.3 Sterilization Cycle. The typical sterilization cycle
consists of five phases: (1) presterilization conditioning,
(2) sterilization, (3) evacuation, (4) air wash, and (5) aeration.
Figures 3-2 and 3-3 show pressure/time curves for the first four phases of
the 12/88 sterilization cycle and the pure EO sterilization cycle,
respectively. Steps 1 through 4 typically require about 8 hours at larger
commercial sterilization facilities, and about 2 to 4 hours at hospitals.
3.2.1.3.1 Presterilization conditioning. After the products have been
loaded into the chamber and the airtight door sealed, a partial vacuum is
drawn inside the chamber. This initial vacuum, or drawdown, prevents
dilution of the sterilant gas. Also, if flammable sterilant gases are
used, the removal of air reduces the potential for ignition.12 The
chamber pressure is reduced to a pressure of about 6.9 to 69 kPa (1 to
10 psia) for 12/88 and 3 kPa (0.4 psia) for pure EO. The initial drawdown
takes from about 5 to 45 minutes, depending on the product being
sterilized. Certain products require a longer drawdown time because they
are damaged by sudden pressure changes. The chamber temperature is then
adjusted to between 38°C (100°F) and 54°C (130°F). A higher temperature
will increase the diffusion rate of EO into the products and, thus, will
reduce the time the products must be exposed to the sterilant gas to
ensure proper sterilization. Finally, the relative humidity is raised to
3-10
-------
HUMIOlflCAIlON
&
CONDI TONING
0 HOUR
1. PRESTERILIZATION CONDITIONING
2. STERILIZATION
8 HOUR
3. EVACUATION
4. AIR MASH
Figure 3-2.
Sterilization cycle for 12/88. (Courtesy of Union Carbide Corporation, Linde Division.)
-------
OJ
I
ro
0 HOUR
1. PRESTERILIZATION CONDITIONING
2. STERILIZATION
8 HOUR
3. EVACUATION
4. AIR WASH
Figure 3-3. Sterilization cycle for pure EO. (Courtesy of Union Carbide Corporation
Linde Division.) '
-------
about 45 percent by injecting steam. Proper numidification is important
to the process because the susceptibility of microorganisms to the
sterilant gas is increased under moist conditions.12
3.2.1.3.2 Sterilization. The sterilant, which is supplied as a
liquid, is vaporized and introduced into the chamber to achieve the
desired concentration of EO. The chamber pressure depends on the type of
sterilant gas used. Pure £0 is used under a slight vacuum at pressures of
about 94 kPa (13.7 psia); the 12/88 mixture is used at pressures of about
170 kPa (24.7 psia). The pressure is held for about 4 to 6 hours. This
exposure time is dependent on the temperature, pressure, humidity level,
type of sterilant gas, and products being sterilized. For example, porous
products require shorter exposures than nonporous products. Also, some
bacteria are more resistant to EO and take longer to destroy.
3.2.1.3.3 Evacuation. Following sufficient exposure time, the
sterilant gas is evacuated from the chamber with a vacuum pump. Typical
evacuation pressures are 13 kPa (1.9 psia) for 12/88 gas and 3 kPa
(0.4 psia) for pure EO. This postcycle vacuum phase lasts about
10 minutes.
3.2.1.3.4 Air wash. The pressure in the chamber is brought to
atmospheric pressure by introducing air (when nonflammable sterilant gases
are used) or either nitrogen or C02 (when flammable sterilant gases are
used). The combination of evacuation and air wash phases is repeated from
two to four times to remove as much of the EO from the product as
possible. The air wash typically lasts 2 to 15 minutes.
The purpose of the air wash is to allow residual EO to diffuse from
the product. Removal of EO from the product during the air wash helps
meet Food and Drug Administration (FDA) guidelines on residual EO levels
for medical devices, EPA residual tolerances for agricultural products,
and the OSHA standard for exposure in the workplace.
3.2.1.3.5 Aeration. After the last air wash, the chamber doors are
opened, and the sterile products are placed in an aeration room and kept
there for several hours to days depending on the product. The purpose of
aeration is to allow further diffusion of residual EO from the products
prior to shipping to comply with the FOA and EPA residual EO guidelines.
Ethylene oxide concentrations in the aeration room are maintained at
3-13
-------
relatively low levels by ventilating the room at a rate of about 20 air
changes per hour.
Recent information from industry contacts indicate that some
commercial sterilization facilities are aerating some or all of the
sterile products in heated enclosed aeration cells. In comparison to
traditional warehouse-type aeration rooms, these cells are smaller in
volume (<70m3 [2500 ft3]) with much lower ventilation rates.
Consequently, the EO concentrations are usually higher than the 1 ppmv
OSHA standard. However, worker exposure is reduced by not opening the
door until the EO concentration drops and by limiting the frequency of
opening the door. The main purpose of this type of aeration process is to
increase the diffusion rate of EO out of the sterile product (by
increasing the temperature) and, thus, reduce the aeration time.
Facilities that sterilize products infrequently may aerate in the
sterilization chamber. Two basic chamber aeration processes are used.
The first process involves cycling the chamber between atmospheric
pressure and a slight vacuum pressure (i.e., a pressure of about 94 kPa
[13.7 psia]) several times over a 12- to 24-hour period. The length of
the cycles depends on the chamber size and vacuum pump capacity. The
second process involves drawing an extreme vacuum (about 0.6 kPa
[0.1 psia]) in the chamber and holding the vacuum for 24 to 48 hours.
Some hospitals and commercial sterilization facilities with smaller
sterilizers (less than 1 m3 [40 ft3]) use aeration chambers (or cabinets),
which are similar to the sterilization chambers in size and design.
Sterile products at hospitals are aerated for about 24 hours.
3.2.2 Single-Item Sterilization System
Four of the 203 commercial sterilization facilities (2 percent) that
responded to the HIMA survey or the July 1986 EPA information request
reported the use of a single-item sterilization system.1'2 Three of these
facilities use the Sterijet® system manufactured by H. W. Andersen
Products; one facility uses another patented system that is similar to the
Sterijet® system. In contrast to the bulk sterilization chambers used by
most commercial sterilization facilities, these systems are designed to
sterilize small individual items (such as medical equipment supplies) in
sealed pouches. Marketing of these systems is primarily focused on
hospital sterilization.15
3-14
-------
The single-item sterilization systems consist of (1) a machine that
delivers the sterilant gas through a nozzle, (2) flexible plastic pouches,
and (3) an aeration cabinet. The process involves the following steps.
The product to be sterilized is placed in a plastic pouch. With the open
ends of the pouch sealed around the nozzle, a slight vacuum is drawn in
the pouch followed by injection of a premeasured quantity of sterilant
gas. The amount of sterilant gas injected depends on the size of the
pouch. After the gas is injected, the nozzle is automatically withdrawn,
and the pouch is heat sealed. The sealed pouches are placed directly into
an aeration cabinet or temperature-controlled aeration room. The enclosed
product is sterilized prior to the escape of the gas through the pouch,
which is designed to retain the EO long enough to ensure proper
sterilization. The products are sterilized for approximately 12 hours at
about 50°C (122°F) and aerated for 36 hours.15
3.2.3 Beehive Fumiqators
The process for beehive fumigators is essentially the same as bulk
sterilization; however, a unique feature of the fumigators warrants a
separate discussion. Whereas the sterilization processes described above
are performed at one location, six of the eight State departments of
agriculture represented in the EPA sterilization data base use portable
chambers to fumigate beehives.2 These fumigators are transported to and
used at numerous and variable locations in each of the six States. The
State departments of agriculture use an E0/C02 sterilant gas mixture.
Typically, a garden hose is connected to the fumigation chamber and is
placed along the ground for venting the sterilant gas during the
evacuation phase of the sterilization cycle. After the evacuation, the
beehive is removed from the chamber and aerated in the open air.
3.3 EMISSION SOURCES
The three principal sources of EO emissions from sterilization/
fumigation processes are (1) the sterilizer vent(s) (i.e., the vent on the
vacuum pump gas/liquid separator), (2) the sterilization chamber vacuum
pump drain (assuming that a once-through, water-ring vacuum pump is used),
and (3) the aeration room vent. A schematic of these emission sources is
shown in Figure 3-4. Other potential emission sources are equipment leaks
and storage and handling. For the purposes of developing emission
3-15
-------
(760 Mq/yr)
(1,000 Mg/yr> no Mq/yr)
VENT OR EMISSION
VENT — CONTROL DEVICE
(GAS)
VENT
SEPARATOR
(LIQUID)
DRAIN
ETHYLENE
OXIDE
"900UCTS FOR
STERILIZATION
STERILIZATION
CHAMBER
STERILIZED
PRODUCTS
AERATION
300M
Figure 3-4. Schematic of emission sources at commercial
sterilization facilities.
(Does not include hospitals).
3-16
-------
estimates and because bulk sterilization processes are the main source of
emissions, emission sources were assumed to be the same for both
sterilization processes (i.e., bulk and single-item).
3.3.1 Sterilization Chamber Vents
Sterilization chamber vent emissions are associated with the chamber
vacuum pump. These vacuum pumps are typically once-through, liquid-ring
designs that use water as the working fluid. During the evacuation phase
of the sterilization'cycle, a mixture of chamber gas and water is expelled
from the pump to a centrifugal gas/liquid separator. In the separator,
gas-phase EO is directed to a vent and emitted to the atmosphere. The
liquids from the separator are directed to a sewer drain.
3.3.2 Sterilization Chamber Vacuum Pump Drains
Some of the EO that is released from the chamber during the
evacuation phase enters the liquid-phase separator line with the vacuum
pump water. Although some EO may be hydrolyzed to ethylene glycol, the
conversion rate at ambient temperatures is extremely slow, requiring weeks
for completion (see Figure 3-5).8 Also, EO is rapidly released from an
aqueous solution when agitated.16 Therefore, virtually all of the EO that
dissolves in the vacuum pump water is emitted from the water. The
absorbed EO may be released at the 1-inch air break between the liquid
pipe and drain (required by local plumbing codes) or may diffuse into
other areas of the building as the water passes through the drain
system. Any remaining EO would desorb into the head space of the sewer
pipes (possibly creating flammable mixtures with air) and be emitted as it
passes through the sewer or waste treatment systems.6'8
3.3.3 Aeration Room Vent
All emissions from residual EO in the product are referred to as
aeration room vent emissions. As residual EO diffuses out of the sterile
products in the aeration room or is emitted to the sterilization room when
the chamber door is opened, it is emitted to the atmosphere via room
ventilation. High ventilation airflow rates are used to maintain EO
concentrations below the OSHA limit.
3.3.4 Equipment Leaks
Although equipment component counts (number of flanges, valves, etc.)
were not obtained for the commercial sterilization facilities, observations
3-17
-------
100 r
Figure 3-5. Hydrolysis rates of dilute, neutral aqueous solutions
of ethylene oxide.
(Courtesy of Union Carbide Corporation, Ethylene Oxide/Glycol Division.)
3-18
-------
made during site visits indicated that the number of components is
small. However, control of equipment leaks may be important to meet the
1 ppmv OSHA standard. For the purposes of this analysis, equipment leak
emissions are assumed to be negligible.
3.3.5 Storage and Handling
Ethylene oxide at commercial sterilization facilities and hospitals
is typically stored in pressurized cylinders rather than bulk
containers. Therefore, material losses associated with loading and
unloading bulk quantities of EO and storage tank breathing losses would
not occur. Although bulk storage of sterilant gas at sterilization
facilities is rare, at least one commercial sterilization facility stores
bulk quantities of 12/88 in a pressure vessel. During transfer of the
12/88 from the tank truck to the pressure vessel, the vessel and the tank
truck are vapor balanced. Therefore, emissions during transfer are
expected to be negligible. Also, because the storage tank is a pressure
vessel, no emissions should occur during routine operation. Consequently,
commercial sterilization facilities and hospitals are likely to have
negligible storage and handling emissions.
3.4 EMISSION ESTIMATES
3.4.1 Commercial Sterilization Facilities
The emission estimate for commercial sterilization facilities is
based on the facility-specific annual EO usages and emission control
levels reported in the 203 responses to the HIMA survey and the July 1986
EPA information request. Average EO emissions from these commercial
sterilization facilities, based on total sterilizer volume, are presented
in Table 3-6. The total amount of EO used by the 203 commercial
sterilization facilities (i.e., not hospitals) represented in the EPA data
base is 2,270 Mg/yr; approximately 16 percent (i.e., 370 Mg/yr) of this
amount is controlled. Therefore, the EO emission estimate for the
203 facilities represented in the EPA commercial sterilization data base
is 1,900 megagrams per year (Mg/yr).1'2 Of this amount, it is estimated
that 760 Mg/yr are emitted from sterilizer vents, 1,000 Mg/yr are emitted
from sterilization chamber vacuum pump drains, and 110 Mg/yr are emitted
from aeration room vents (see Figure 3-4). These estimates were developed
using the HIMA survey, the July 1986 EPA information request responses,
and the following assumptions:
3-19
-------
TABLE 3-6. AVERAGE EMISSIONS FROM COMMERCIAL STERILIZATION FACILITIES-
FDA nflTA nacr1.2
EPA DATA BASE •
Total chamber
volume at
facility, m1 (ft3)
<11 (<400)
11-56 (400-2,000)
>56 (>2,000)
No. of
facilities3
88
77
38
Mean EO use,
kg/yr (Ib/yr)
660 (1,500)
7,600 (17,000)
43,000 (94,000)
Mean EO emissions,
kg/yr (lb/yr)b c
640 (1,400)
6,800 (15,000)
34,000 (75,000)
jjDoes not include hospitals.
Mean emissions are less than mean EO use because of existing controls.
Emissions from all sources (i.e., sterilizer vent, vacuum pump drain
aeration).
3-20
-------
1. All of the EO reported as used in the sterilization process is
evacuated from the sterilization chamber or released from the product
during aeration.
2. Within each facility, EO emissions are distributed among three
emission points. The three emission points and the percentage of total EO
emissions allocated to each are:
a. Sterilizer vent(s)—50 percent;
b. Sterilization chamber vacuum pump drain~45 percent; and
c. Aeration room vent(s)--5 percent.
This 50/45/5 percent split is based on industry estimates, limited test
data, and engineering judgment.17
3. For the 355 sterilization chambers in the EPA commercial
sterilization data base that are uncontrolled, all of the EO that enters
the chamber vent(s) is released to the atmosphere. For the
79 sterilization chambers with emission control devices, the chamber vent
emissions are controlled at the efficiencies reported on the HIMA survey
and EPA information request responses.
4. At each facility, all of the EO that dissolves in the vacuum pump
water and subsequently enters the drain is assumed to be emitted
uncontrolled to the atmosphere at an outdoor ground-level drain near the
facility. This assumption is consistent with test data that suggest EO is
rapidly released from an aqueous solution when agitated.16
5. At each facility, all of the EO that enters the aeration room
vent is released uncontrolled to the atmosphere.
3.4.2 Hospitals
The EO emission estimate for hospitals is based on data from the
approximately 80 responses to the 1986 information request to hospitals
and information in the 1988 American Hospital Association (AHA) hospital
data base. Linear regression analyses of the 1986 data indicated that the
annual EO use correlates better with the number of hospital beds (r2 =
0.77) than with the number of surgical procedures (r2 = 0.68).18 A
nationwide EO use rate of approximately 1,000 Mg/yr was obtained by
extrapolating the 1986 data to the 1988 AHA data base, which contains
hospital-specific information on the number of beds for
7064 hospitals.19 Because the majority of hospitals do not use EO
3-21
-------
emission controls, EO emissions from hospitals are assumed to equal the EO
use of approximately 1,000 Mg/yr. Average EO emissions for hospitals,
based on the number of hospital beds, is presented in Table 3-7.
3.5 CURRENT REGULATIONS
3.5.1 Occupational Safety and Health Administration Standard
In 1984, OSHA established a permissible exposure limit for
occupational exposure to EO of 1 pprav determined as an 8-hour time-
weighted average (TWA) concentration. In addition, an action level of
0.5 ppmv as an 8-hour TWA was established as the level above which
employers must monitor employee exposure.20 In April 1988, OSHA
established a short-term excursion limit (EL) for occupational exposure to
EO emissions of 5 ppmv averaged over a 15-minute sampling period.21
3.5.2 State Regulations
Existing State regulations for EO are summarized in Table 3-8.
Several States are currently regulating EO or developing air toxics
22_28
programs.
3-22
-------
TABLE 3-7. AVERAGE EMISSIONS FROM HOSPITAL STERILIZERS
3,19
Hospital
size range
Small (<200 beds)
Medium (200 to 500 beds)
Large (>500 beds)
No. of
hospitals
4,907
1,645
512
Mean EO use,
kg/yr (lb/yr)d
70 (150)
200 (430)
790 (1,740)
aBecause most hospitals do not control EO emissions, the EO
emissions are assumed to equal the EO use.
3-23
-------
TABLE 3-8. STATE REGULATIONS FOR ETHYLENE OXIDE EMISSIONS
22.26
State
Florida3
Michigan3
Missouri
New Jersey
New York3
Ok Iahoma
Puerto Rico
Rhode Island3
Tennessee
Texas
Utah
Vermont
Virginia
Wyomi ng
Regulatory description
California • Developing air toxics program but a regulation may not be proposed fo~
i y0sr•
• South Coast—groposed rule for new (or modified) sources based on
maximum 10 * nsk level, including aeration processes.
• Bay Area—draft rule for new and existing sterilizers; no drain
emissions; 99.5 percent control of vent emissions if EOTuse exceeds
250 Ib/yr: exemptions—steriIizers smaller than 250 ft3 and aeration
procssscs.
Colorado • Regulate as a volatile organic compound (VOC).
- ... ^ * Reasonably available control technology (RACT) required for new source
Connecticut . Best avaiIabIe control technology (BACT) required for alI new "r
mod,f,«d sources exceeding a maximum allowable stack concentration
• MASC is calculated using exhaust gas flow rate, stack height, and the
distance from the discharge point to the property line. MASC would be
cycles. Therefore, BACT required on^ew^o/modff ied^sources'°"
Existing sources exceeding the maximum allowable ambient concentration
of 0.01 ppm have 3 years to comply with orders given by the
Connecticut Department of Environmental Protection
• Maximum risk level of 10'° for new or modified sources.
• BACT for all new sources. Requires emissions be indectable or subjected
to risk analysis (maximum allowable risk level is 10~6) For
industrial sterilizers using typical sterilization cycles, a control
erriciency based on a risk assessment analysis would be greater than
99 percent by weight.
• Regulate as a VOC.
• Regulate as a VOC.
• BACT requfred for new or modified sources.
' 2?Hr0x l"od!fied sources must receive 99 percent control or greater or
BACT (also at permit reviews) grearer, or
' l?AAiir«*TJ£lJm/P¥t, must."ot e,x.?eed guideline Acceptable Ambient Level
(AAL) of 6.67 yg/mj (a revised AAL of 0.019 yg/m7 is anticipated for the
next edition of Air Guide-1 [to be released by 01/901
• Certificate of operation includes the following statement-
Should significant new scientific evidence from a recognized
institution result in the decision by DEC that lower ambient levels
must be established, it may be necessary to reduce emissions from this
source prior to the expiration of this Certification of Operation."
Maximum ambient air concentration at property line is 1/100 of TLV.
Regulate as a VOC.
Emission control.s required for emissions greater than 3 Ib/h or 15 lb/d
Maximum risk level of 10'6 for new and existing sources
If BACT is used, nay consider 10~3 risk level.
Regulate under standards for process and nonprocess emissions.
BACT required for all new sources.
BACT required for alI new or modified sources. BACT requirements to go
into effect for existing sources.
Following the programs developed in New York.
Regulate as a VOC.
For any 24-hour concentration exceeding 1/100 of the TLV-TWA both
^ffln3 KndJ!e"1,faC.M!ties are re
-------
3.6 REFERENCES FOR CHAPTER 3
1. Letter and enclosures from J. Jorkasky, Health Industry Manufacturers
Association (HIMA), to D. Markwordt, EPA:CPB. February 21, 1986.
Survey responses from HIMA members.
2. Responses to July 1986 Section 114 information request regarding the
use of ethylene oxide by miscellaneous sterilization and fumigation
facilities.
3. 1988 Abridged Guide data base. American Hospital Association, 840
North Lake Shore Drive, Chicago, Illinois 60611.
4. Commercial Sterilization Standard Industrial Classification (SIC)
data base. Research Triangle Institute. July 1987. SIC
designations for facilities in the EPA commercial sterilization data
base.
5. Responses to the January 1986 Section 114 information request to
hospitals that use ethylene oxide as a sterilant.
6. Letter from Buonicore, A., Chemrox, Inc., to Markwordt, D.,
EPA:CPB. August 27, 1984. Comments on the sources of ethylene oxide
emissions draft report.
7. Responses to July 1988 information request to commercial
sterilization facilities regarding chamber operating parameters,
current controls, vacuum pumps, and aeration rooms.
8. Ethylene Oxide Product Information Bulletin. Union Carbide Corp.,
Ethylene Oxide/Glycol Division. 1983.
9. Ethylene Oxide: Material Safety Data Sheet. General Electric.
April 1983.
10. Dichlorodifluoromethane: Material Safety Data Sheet. Genium
Publishing Corporation. February 1986.
11. Handbook of Chemistry and Physics. 67th Edition. CRC Press, Boca
Rotan, Florida. 1986.
12. Gas Sterilants. Product information brochure. Union Carbide Corp.,
Linde Division. Undated.
13. Telecon. Taylor, G., MRI, with Conviser, S. and Woltz, C., Union
Carbide Corp., Linde Division. July 31, 1987. Discussion of
operating pressures for sterilization chambers.
14. Letter from Burley, R., Environmental Tectonics Corp., to Wyatt, S.,
EPArCPB. August 25, 1987. Comments on draft BID Chapter 3 for
ethylene oxide NESHAP.
3-25
-------
15. Mitigation of Worker Exposure to Ethylene Oxide. Goldqraben, R and
Zank, N. The Mitre Corp. 1981.
16. Conway, R., Wagg, G., Spiegel, M., and Berglund, R. Environmental
Fate and Effects of Ethylene Oxide. Environmental Service and
Technology. 1983. 17(2):107-112.
17. Abrams, W., McCormick and Company, Inc. Project No. 075320
Treatment of Spices-EtO Mass Balance. Final Report. November 26,
1985.
18. Memorandum. Nicholson, B. and Srebro, S., MRI, to Patel, N.
EPA/OAR. Baseline Freon 12* Emissions from Hospital Sterilization
Processes. September 30, 1986.
19. Memorandum. Markwordt, 0., EPA/CPB. Documentation of Human Exposure
Model Parameters for Ethylene Oxide Emissions from Hospitals
January, 1989.
20. Ethylene Oxide. Occupational Safety and Health Administration
Promulgated on June 22, 1984. 49 FR 25797. Office of the Federal
Register. Washington, D.C.
21. Occupational Exposure to Ethylene Oxide. Occupational Safety and
Health Administration. Promulgated on April 6, 1988. 29 CFR
Part 1910. Office of the Federal Register. Washington, D.C..
22. Summary of Regulations Pertaining to Ethylene Oxide by State.
Chemrox, Inc. Bridgeport, Connecticut. Undated.
23. Air Pollution Control. The Bureau of National Affairs, Inc
Washington, D.C. January 1987.
24. Telecon. Shine, B., MRI, with Vincent, R., California Air Resources
Board. February 14, 1989.
25. Telecon. Shine, B., MRI, with Glenn, J., Florida Department of
Environmental Regulation, Division of Air Resources Management.
February 14, 1989.
26. Telecon. Shine, B., MRI, with Schleusener, P., Michigan Department
of Natural Resources, Air Quality Division. February 14, 1989.
27. Telecon. Shine, B., MRI, with Wade, E., New York Department of
Environmental Conservation Division of Air Quality. February 14,
1989.
28. Telecon. Shine, B., MRI, with Morin, B., Rhode Island Department of
Environmental Management, Division of Air and Hazardous Materials
February 14, 1989.
3-26
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4. EMISSION CONTROL TECHNIQUES
4.1 BULK STERILIZATION PROCESSES
The three principal sources of ethylene oxide (EO) emissions from
bulk sterilization processes are:
1. The sterilizer vent(s) (i.e., the vent on the vacuum pump
gas/liquid separator);
2. The sterilization chamber vacuum pump drain; and
3. The aeration room vent.
The following sections describe the techniques available to control
EO emissions from these three sources. Table A-2 in Appendix A presents a
list of the emission control devices and manufacturers.
4.1.1 Sterilization Chamber Vent Emissions
Three primary techniques are used to control EO emissions from
sterilizer vents: hydrolysis, oxidation, and condensation. Ethylene oxide
is catalytically hydrolyzed to form ethylene glycol; oxidation decomposes
EO into carbon dioxide and water; and condensation allows the recovery of
the sterilant gas mixture. A fourth control technique for sterilizer
vents is a gas/solid reactor system that chemically reacts EO and binds it
to the solid packing of the reactor.1
Table 4-1 shows the emission control techniques and devices used by
the 203 commercial sterilization facilities (i.e., not hospitals)
represented in the EPA data base (refer to Chapter 3 for a description of
the contents and origin of the data base). Twenty-seven of these
203 commercial sterilization facilities (13 percent) reported the use of a
control device for sterilizer vent emissions. Nineteen of these
27 facilities use one emission control device for multiple chambers by
manifolding the chamber vents and staggering the evacuation of the
sterilant gas from the chambers. The remaining eight facilities control
emissions from single chambers.2'3
Nine additional commercial sterilization facilities reported the use
of a neutral-water scrubber to control EO vent emissions. Neutral-water
scrubbers reduce EO vent emissions by "washing" a portion of the EO to the
drain (facilities reported 20 to 100 percent of the total EO emissions
from the sterilizer chamber were "controlled" by a neutral-water
4-1
-------
-pi
I
TABLE 4-1. ETHYLENE OXIDE EMISSION CONTROL DEVICES FOR STERILIZER
VENTS-EPA COMMERCIAL STERILIZATION DATA BASE5*3
Emission control technique and device
Hydrolysis
Packed scrubber
Reaction/detoxification tower
Caustic scrubber
Oxidation
Flare
Catalytic oxidizer
Condensation
Condensation/reclamation system
TOTAI '
"Control efficiencies are those reported
Control
ef f iciency ,
percent3
99. Oc
99.0
30.0 and 95.0
98.0
99.0
50.0 - 86.0
-•
by the 203 comnu
No. of
facilities
(percent)6
14 (7)
2 (1)
1 (0.5)
2 (1)
1 (0.5)
7 (3)
27 (I3)e
«=-«>-=-="=»=
arcl al <;t»r i i i , =.
No. of
chambers
(percent)b
45 (10)
4 (1)
2 (0.5)
5 (1)
1 (0.2)
20 (5)
77 (18)f
======
Chamber
size, m3 (ft3)
4- HO
(140-6,000)
4-27
(140-960)
32 and 60
(1,150 and 2,120)
2-77
(60-2,720)
4
(130)
5-45
(190-1,580)
=S==s=^=i^='S5^*=SBHSSSS^^S^B^K
EO usage/
facility, Mg/yr (Ib/yr)
— . .
0.9-59
(2,000-130,000)
4 and 57
(9,500-126,000)
44
(98,200)
34 and 80
(74,200 and 176,000)
0.4
(1,000)
7-46
(15,000-100,800)
790 (1,750,000)
EPA-sponsore "
'a' ^-^IS ol'S^^^ efficiencies ranging from 96.0 to
that Can be achieved o« a continuous JLs4 "rubbers .ndicates that 99.0 percent is the maximum
^^ efficiencies of 99.0 and 99.7 percent
eachive at least 98 percent destruction efficienc! §PeC'fled con<"tions of waste gas heat content and flare exit velocity wilt
f Total number of facilities = 203.
Total number of chambers = 434
R.,r.S.n,s 35 p.rcen, ., ,„. tofa, E0
-------
2 3
scrubber). » Some cf the £0 that is washed to the drain may be converted
by hydrolysis to ethylene glycol; however, the conversion rate of EO to
ethylene glycol in neutral water at ambient temperatures is extremely
slow, requiring weeks for completion.*3 Since EO is rapidly released from
an aqueous solution when agitated, the vast majority of the EO washed to
the drain will off-gas uncontrolled from the air break in the drain line,
sewer lines, or the waste treatment system.s~8 Because the use of
neutral-water scrubbers merely changes the EO emission source, they are
not discussed here as a control technique.
The majority of hospitals do not control EO emissions from sterilizer
vents. However, some hospitals use emission controls because of State and
local regulations. Catalytic oxidation and the gas/solid reactor system
are two techniques that are known to be used by hospitals to control EO
emissions from sterilizer vents.9"11
4.1.1.1 Hydrolysis. Hydrolysis is the most common EO emission
control technique used by commercial sterilization facilities.2'3 This
technique is applicable for both pure EO and EO/inert gas mixtures such as
12/88 (12 percent by weight EO and 88 percent by weight dichlorodi-
fluoromethane [CFC-12]) and 10/90 (10 percent by weight EO and 90 percent
by weight carbon dioxide). The majority of commercially available
hydrolysis control devices are not designed for the low flow rates
associated with chamber volumes less than 1.4 m3 (50 ft3) and are,
therefore, not applicable to the control of most hospital sterilization
chambers. However, two manufacturers have designed scaled-down acid-water
scrubbers for flow rates less than 0.3 cubic meters per minute (m3/min)
[10 cubic feet per minute (ft3/min.)].1l*12
Ethylene oxide can be hydrolyzed under relatively mild conditions to
ethylene glycol products (without affecting the inert gas) as shown in the
following reaction:
C2H,0 + H20 » HOCH2CH2OH + HO(CH2CH2)nOH
H+ or OH- n
Ethylene glycol Polyethylene glycols
4-3
-------
Ethylene oxide will hydrolyze in neutral water, but this reaction is very
slow. (The half-life of EO in neutral water at ambient temperatures is
approximately 14 days.)8 The reaction rate is increased in an acidic or
basic solution. The reaction is approximately two orders of magnitude
faster under acidic conditions than under basic conditions, making acid
hydrolysis the preferred method. Sixteen of the 203 commercial
sterilization facilities represented in the EPA data base reported using
acid-water scrubbers; one facility reported using caustic scrubbers to
control EO emissions.2'3
4-1-1-1.1 Packed scrubbers. Figure 4-1 is a schematic of a packed
scrubbing system used to control EO emissions. The system consists of a
countercurrent packed tower, a reaction vessel, and a holding tank. In
the countercurrent tower, the sterilant gas is contacted with an acidic
water solution, generally aqueous sulfuric acid. Because EO is extremely
water soluble, most of the EO is absorbed into the scrubber liquor. Next,
the liquor is sent to the reactor vessel, which is a small storage tank
operated at atmospheric pressure, to complete the hydrolysis of EO. After
the reaction is complete, the liquor is sent to the storage vessel. The
liquor in the storage vessel is recirculated to operate the tower until
the concentration of the ethylene glycol in the liquor reaches a predeter-
mined weight percentage, past which point the scrubber efficiency
declines. Manufacturers of packed scrubbing systems suggest that the
scrubbing liquor is spent when the solution is 30 to 40 percent by weight
ethylene glycol. I3*l
-------
H20/H2SOH/ETHYLENE GLYCOL SOLUTION
STERILIZER
VACUUM PUMP
LIQUID-GAS
SEPARATOR
LIQUID
HEAT
EXCHANGER
Figure 4-1. Countercurrent packed scrubbing system.
-------
sterilization facilities ranges from 0.9 Mg/yr (2,000 Ib/yr) to 59 Mg/yr
(130,000 Ib/yr).2'3
Manufacturers of countercurrent packed scrubbers designed to control
EO emissions from sterilizer vents claim EO removal efficiencies greater
than 99 percent. 1'13'15 For a 12/88 sterilant gas mixture, the average EO
removal efficiency for three tests was 99.0 percent by weight (individual
test results were 99.0, 98.7, and 99.4 percent).16 These tests were
conducted using a scrubber that was designed to achieve an EO removal
efficiency of 99 percent. A representative of the manufacturer of the
tested acid-water scrubber stated that the company can design scrubbers to
achieve virtually any EO removal efficiency with any type of sterilant
gas. The results of an EPA-sponsored test on another acid-water
scrubber designed by this company indicated an EO removal efficiency
greater than 99.9 percent for 12/88.18 For pure EO, the EO removal
efficiency was greater^than 99.98 percent for each of four tests performed
at two facilities.16'19 However, a detailed review of the available test
data indicates that 99.0 percent is the highest EO removal efficiency that
can be achieved on a continuous basis."*
4-1-1-1.2 Reaction/detoxification towers. Another acid hydrolysis
scrubbing technique for EO emission control is a reaction, or
detoxification, tower. A schematic of this system is shown in
Figure 4-2. This system consists of a tank that holds the scrubbing
liquor, which is a sulfuric acid solution at a pH of 0.5 to 2.5. The
sterilant gas is bubbled upward through the liquor. The EO is absorbed
into the liquor where it hydrolyzes to ethylene glycol. The gas stream
then flows through the liquid surface and a demister. The demisting pad
prevents acid mist from exiting with the scrubbed gas and provides a final
hydrolysis reaction site for any EO remaining in the gas stream. Inert
gases (i.e., CFC-12 and C02) are exhausted unreacted to the atmosphere.
After ethylene glycol builds up in the stream to a maximum recommended
level^of 60 percent, the scrubber liquor is neutralized and disposed or
sold. (See Section 4.1.1.1.3 for a more detailed discussion of waste
disposal.) Possible methods of determining the scrubbing liquor changeout
point include (1) liquid level indicators, (2) specific gravity detectors,
and (3) measuring the amount of EO charged to the sterilizer. Reaction
4-6
-------
STERILIZER
SCRUBBED
GAS
-p-
i
I
I
I
L
HEAT
EXCHANGER
1
DETOX-
IFICATION
TOWER
DEHISTER
AQUEOUb 1
ACID /
SOLUTION <
r
1
IQUEOUS
U.KALINE
SOLUTION
I
HAItK
SUPPLY
Figure 4-2. Detoxification tower control system.
-------
towers are effective for chambers ranging from 1.4 m3 (50 ft3) to 45 m3
(1,600 ft ). • Two of the 203 commercial sterilization facilities
represented in EPA's data base use reaction towers to control EO emissions
from sterilizer vents. The sterilizers at these two facilities range in
volume from 4 m (140 ft3) to 27 m3 (960 ft3). One of these facilities
uses 4 Mg (9,500 Ib) of EO per year; the other uses 57 Mg (126,000 Ib)
annually. »
Manufacturers of reaction/detoxification towers claim 99+ percent EO
removal efficiency by weight.21'22 Third-party laboratory test results
indicate that EO emission reductions greater than 99.8 percent can be
achieved with reaction towers.23 However, a detailed review of the avail-
able test data indicates that 99.0 percent is the highest EO removal
efficiency that can be achieved by acid hydrolysis techniques on a
continuous basis.**
4.1.1.1.3 Waste disposal. The spent liquor from acid hydrolysis of EO
is typically 40 to 60 weight percent ethylene glycol and has a pH of 0 5
to 2.0. Because of the low pH, the solution is considered a hazardous
waste and, thus, requires special handling procedures for shipping if not
neutralized. However, the spent liquor can easily be neutralized with
sodium hydroxide (caustic) prior to disposal.
Two recovery companies have been identified that are willing to
purchase the aqueous ethylene glycol solution.2
-------
4.1.1.2.1 Thermal oxidation. Ethylene oxide, wnich has a high
heating value, a relatively low ignition temperature, and a very wide
range of mixtures combustible in air (see Table 3-4), can be easily and
efficiently destroyed by thermal oxidation using flares. Thermal
oxidation of EO produces carbon dioxide and water as follows:
2 CjH.,0+5 02 *4 C02+4 H20
thermal oxidation
Two of the 203 commercial sterilization facilities represented in the
EPA data base reported using flares to control EO emissions from the use
of pure EO as a sterilant gas.2 One of these facilities has one 76.7-m3
(2,710-ft ) chamber and uses 80 Mg (176,000 Ib) of EO per year. The other
facility has three chambers ranging in size from 75.2 to 76.9 m3 (2,655 to
2,715 ft ) and one smaller 1.7-m3 (60-ft3) chamber; this facility uses
98 Mg/yr (215,600 Ib/yr) of EO.2 Because of difficulties with sustaining
combustion, commercially available flares are not applicable for
facilities emitting only small amounts of EO.
A manufacturer of flare burners for the control of EO emissions
claims greater than 99 percent control efficiency for pure EO but no data
were provided to substantiate this claim.27 The EPA's position is that
flares operated within specified conditions of waste gas heat content and
flare exit velocity will achieve at least 98 percent destruction efficiency.
Flares can also be used with E0/C02 sterilant gas mixtures (e.g.,
10/90) but are not designed for use with EO/CFC-12 mixtures (e.q.
2728
12/88). » The EPA has not in the past and does not now recommend the
use of flares to control emission streams containing halogenated compounds
(e.g., CFC-12) because corrosive or toxic by-products may form. As shown
below, thermal oxidation of CFC-12 may produce the following corrosive or
toxic by-products at the high temperatures (400° to 800°C [800° to
1500°F1) associated with the use of flares:
CF2C12+02 » COC12 Phosgene
thermal oxidation COF2 Carbonyl fluoride
HC1 Hydrogen chloride
HF Hydrogen fluoride
CF,, Carbon tetrafluoride
C12 Chlorine
CO Carbon monoxide
4-9
5
-------
4.1.1.2.2 Catalytic oxidation. Catalytic oxidation of EO occurs in
the presence of a solid-phase catalyst as follows:
2 CzM+S 02 »4 c,02+4 H20
catalytic oxidation
This control technique is applicable to pure EO, E0/C02 mixtures, and
EO/CFC-12 mixtures. The CFC-12 does not react at the temperatures (150°
to 180°C [300° to 350°F]) that occur during catalytic oxidation, and,
therefore, the toxic CFC by-products that result from the higher
temperatures associated with thermal oxidation are not produced. During
an EPA-sponsored test of a catalytic oxidation unit, no CFC decomposition
by-products were detected; the detection limit was 200 parts per billion
(ppb) for the analyte chloride ion. The maximum operating temperature of
the unit during testing was 155°C (311°F).12
A schematic of a catalytic oxidizer is shown in Figure 4-3. The
spent sterilizer gas is first mixed with a large volume of air to reduce
the control device inlet EO concentration to 5,000 ppmv or less. This
dilution prevents excessive cataTyst bed temperatures (which can damage
the catalyst) from occurring during the oxidation of EO. The gas stream
passes through a filter for dust removal and then is preheated to the
reaction temperature with steam or electricity. The gas then enters the
catalyst bed(s) where the EO is oxidized. Part of the exiting gas stream
may be recycled for heat recovery before being vented to the atmosphere.
One manufacturer also sells a catalytic oxidizer that uses excess
catalyst, instead of diluent air, to absorb the heat of oxidation.29
Because of cost considerations, the excess-catalyst system has been used,
thus far, only for chambers less than 1 m3 [40 ft3]) in volume.29
Recent information indicates that the use of catalytic oxidation to
control EO emissions is increasing, particularly for hospital sterilizers
Q 1 A
and other small chambers. • In general, the large amount of diluent air-
required for most catalytic oxidation systems has limited the use of this
technique to smaller, hospital-size chambers. Also, some of the
manufacturers of hospital sterilizers are developing sterilizers that are
evacuated with air ejectors instead of a vacuum pump.30 The emissions are
then routed to a catalytic oxidizer.30
4-10
-------
STERILIZER
TO ATMOSPHERE
ON FAILURE L
AIR
1,500 CFM
FILTER
STEAM
COIL
CATALYST
BED
STEAM
9 PSIG
HEAT RECOVERY
FAN
TO ATMUbPIII HI
Figure 4-3. Catalytic oxidation system.
-------
Only one of the 203 commercial sterilization facilities represented
in the EPA data base reported the use of a catalytic oxidizer in 1986 to
control EO emissions from the chamber vent.2 This facility has one 4-m3
(130-ft ) chamber and uses 0.4 Mg/yr (1,000 Ib/yr) of EO in an E0/C02
sterilant gas mixture.2 However, data obtained in 1988 indicated that at
least one additional commercial sterilization facility has installed a
catalytic oxidation system to control EO emissions from a larger
industrial-size sterilizer (17 m3[600 ft3]); the EO concentration to the
control unit is regulated by throttles.31
Because catalytic oxidation is applicable to the control of low EO
concentrations, many facilities manifold other EO emission sources (e.g.,
aeration chambers or room, sterilizer hood and door vent, and the gas
cylinder room) to the control device. In addition, if the catalytic
oxidizer requires diluent air, these low-concentration emission sources
can provide part or all of the necessary diluent.
Manufacturers of catalytic oxidation units claim EO destruction
efficiencies greater than 99.9 percent.32'33 Third-party testing and an
EPA-sponsored test support these claims for small (<30 ft3)
sterilizers.12'32
4.1.1.3 Condensation/Rec1amation Systems. Recovery of sterilant gas
mixtures is possible using a reclamation system. The sterilant gas
mixtures will condense under conditions of reduced temperature and
increased pressure, but precautions are necessary to avoid explosions.
Figure 4-4 is a schematic of a sterilization chamber room and a
condensation/reclamation system for a 12/88 sterilant gas mixture. (See
Table 3-4 for physical and chemical properties of CFC-12.) After each
sterilization cycle, the 12/88 gas is withdrawn and passed through one of
the two desiccant beds next to the chamber. (One of the desiccant beds is
regenerated while the other is in use.) The dried 12/88 gas then passes
to a compressor where it is compressed to 50 psig to improve condensation
3 u
efficiency. The compressed gas is piped to a separate explosion-proof
room where it passes through a pressurized condenser that is chilled by
ethylene glycol to about -18°C (0°F).3l+ The liquid 12/88 mixture is
collected in a pressurized, chilled holding tank. The noncondensed gas is
recirculated to the chamber and back through the condenser. The liquid
4-12
-------
-fa
I
STERILIZER
DESICCANT
BEDS
CONDENSER
COMPRESSOR
TO STORAGE TANK
HOI DING
TANK
R[Ul ENDING
TANK
RECYCLE
Figure 4-4. Condensation/reclamation system.
-------
collected in the holding tank is transferred to a pressurized reblending
tank where the liquid is mixed and its composition determined by infrared
analysis. The liquid is then adjusted to the 12/88 (weight percent) ratio
by adding the necessary amount of EO or CFC-12. When the correct ratio is
obtained, the liquid is transferred to a pressurized storage tank in the
chamber room.
Although the reclamation cycle could be continued indefinitely, the
amount of EO recovered declines to the point where it is not cost
effective to continue the reclamation cycle after about three passes
through the system (i.e., typically 60 to 90 minutes). The majority of
the EO (80 to 85 percent) is recovered during this time. Also, increasing
the reclamation time would require that products spend additional time in
the sterilizer and could affect the plant's operating schedule. However,
even if the reclamation time was increased, this system is not designed
for low EO concentrations. Therefore, if this type of control system is
used, add-on controls (e.g., catalytic oxidation or a small scrubber) need
to be considered for the EO remaining in the chamber after the reclamation
cycle is complete.
Seven of the 203 commercial sterilization facilities represented in
the EPA data base reported the use of condensation/reclamation systems;
three of these facilities reported an 85 percent EO recovery efficiency,
three reported 80 percent, and one reported 50 percent.2'3 These seven
facilities recover E0/C02 and EO/CFC-12 sterilant gases. Six of these
facilities each use over 23 Mg/yr (50,000 Ib/yr) of EO. The seventh
facility uses just over 6.8 Mg/yr (15,000 Ib/yr).2'3 The chamber sizes
range from 5 to 45 m3 (190 to 1,580 ft3) at these seven facilities.2'3
The condensation/reclamation systems currently available are designed
for the high volumetric flow rates of larger, industrial-size chambers.
The systems are not technically or economically feasible for use with
smaller chambers or at facilities that use small amounts of EO. In
addition, the safety hazards (i.e., explosion potential) associated with
this control technique preclude its use in hospitals.
4-14
-------
4.1.1.4 Gas/Solid Reactor. A fourth control technique that is used
by some hospitals to control vent emissions (after acid-water scrubbing)
is a dry, solid-phase system that chemically converts EO and then binds
the product to the solid packing.1 The system operates at room
temperature. There are no liquid waste streams produced; the vendor
handles the disposal of the solid waste that is produced.35 Although the
gas/solid reactor can handle EO concentrations in the percent range (i.e.,
>100,000 ppmv) for brief periods of time, it is designed for low (ppm
range) concentrations such as the exhaust from an acid-water scrubber.
The manufacturer of this device markets a two-stage control system, which
consists of an acid-water scrubber and the gas/solid reactor. (The
company also sells the stages separately.) The majority of the EO is
removed by the scrubber, which is specifically designed for the small
sterilizers (<2 m3 [70 ft3]) used at hospitals. The gas/solid reactor
removes the residual EO exiting the scrubber and, because it is designed
for low EO concentrations, can also be manifolded to other emission
sources (e.g., aeration chambers, sterilizer hood and door, and gas
cylinder storage room).
The manufacturer of this system claims greater than 99.9 percent
efficiency for the gas/solid reactor.1 However, this efficiency is based
on a test performed with an inlet EO concentration of 140,000 ppmv, which
is much higher than the concentration of the scrubber outlet stream. In
another test, no EO was detected (with a lower detection limit of
0.1 ppmv) in the gas/solid reactor outlet stream when the inlet stream
(i.e., scrubber outlet stream) was 2 ppmv EO.35 Because of the innate
problems associated with measuring low EO concentrations, the actual
efficiency of the system under normal operating conditions presently
cannot be determined. (See Section 4.1.3 for a more detailed discussion
of measuring low EO concentrations.) However, the maximum removal
efficiency that the gas/solid reactor can achieve on a continuous basis is
assumed to be 99.0 percent.
4-1-2 Sterilization Chamber Vacuum Pump.Drain Emissions
Ethylene oxide drain emissions result from the use of vacuum pumps
that use once-through water as the working fluid. (Some of the
manufacturers of hospital sterilizers are developing sterilizers that are
4-15
-------
evacuated by air ejectors instead of vacuum pumps.)30 Ethylene oxide is
infinitely soluble in water, and, therefore, a portion of the EO evacuated
from the chamber enters the drain with the vacuum pump water (see
Figure 4-5a). The EO that enters the drain with the vacuum pump water is
subsequently released uncontrolled from the air break in the drain line,
sewer lines, or the waste treatment plant.6'8
The EO drain emissions can be controlled by replacing the existing
once-through vacuum pump with a closed-loop (recirculating) vacuum pump.
The recirculating fluid (sealant) can be water, oil or ethylene
glycol. In this closed-loop system, the water or liquid from the
liquid-gas separator is cooled in a heat exchanger and recirculated
through the vacuum pump (see Figure 4-5b). Because ethylene oxide is not
soluble in oil or ethylene glycol and will off-gas from water as it is
recirculated, nearly all of the EO will be emitted through the liquid-gas
separator (chamber) vent. (Techniques for control of chamber vent
emissions are discussed above.) In addition, mechanical seals are used to
eliminate leakage (and, thus, any EO emissions) from the pump.37
Because the sterilization cycle operates under humid conditions, some
water will be condensed in the liquid-gas separator and, thus, mix with
the liquid sealant in the pump. An overflow collection tank is used to
maintain a constant amount of sealant recirculating in the pump.37 If
ethylene glycol is used as the sealant, the contaminated glycol will
eventually need to be disposed and replaced with a fresh charge.35
However, if oil is used as the sealant, the condensed water can be drained
off the bottom with minimal oil loss because of the immiscibility of oil
, . as
and water.
4.1.3 Aeration Room Vent Emissions
4.1.3.1 Aeration Rooms. Most commercial sterilization facilities
aerate the sterile products in large, warehouse-type aeration rooms that
are typically 280 to 2,800 m3 (10,000 to 100,000 ft3) in volume but may be
larger than 14,000 m3 (500,000 ft3).31 The ventilation rates are,
generally, in the range of 112 to 560 m3/min (4,000 to 20,000 ft3/min) but
may be as high as 1,680 m3/min (60,000 ft3/min).31 These large flow rates
are necessary to maintain a low EO concentration in the room to comply
with the Occupational Safety and Health Association (OSHA) standards (see
4-16
-------
4 :U:SS::.NS
VACUUM
PUMP
EVACUATED GAS FROM
STERILIZATION CHAMBER
WATER
SEPARATOR
VACUUM PUMP WATER
EO DRAIN EMISSION
Figure 4-5a. Once-through liquid-ring vacuum pump.
EVACUATED GAS FROM
STERILIZATION CHAMBER
RECIRC'JLATED
«ATER
EO VENT
EMISSIONS
LI3UIO-GAS
SEPARATOR
VACUUM PUMP
Figure 4-5b. Redrculating liquid-ring vacuum pump.
4-17
-------
Section 3.5). Data from a cross-sectional survey (44 facilities) of the
203 commercial sterilization facilities represented in EPA's data base
indicated an average 8-hour time-weighted average (TWA) EO concentration
of 2.5 to 3 ppmv in aeration rooms.31
Two issues of concern regarding the control of aeration room
emissions are: (1) most EO emission control devices are impracticable for
the low-concentration, high-flow-rate exhaust streams from aeration rooms;
and (2) the lower detection limit of most analytical methods makes it
impossible to determine the true control efficiency of the low EO
concentrations (<1 ppmv) found in most aeration rooms. Hydrolysis,
thermal oxidation, and condensation/reclamation presently have not been
demonstrated to be practicable control techniques for low-concentration,
high-flow-rate gas streams. However, catalytic oxidation and the
gas/solid reactor system have the potential to control aeration room
emissions. Catalytic oxidation units are commercially available to handle
flow rates from less than 1 m3/min (40 ft3/min) to approximately
340 m3/min (12,000 ft3/min).9'38 The catalytic oxidizers are modular, and
systems can be designed to handle higher flow rates; however, the
increased size of the system for high flow rates can restrict its
practical use. Gas/solid reactors are being used for flow rates up to
42 m /min (1,500 ft /min), and systems can be designed to handle any flow
rate; however, as with catalytic oxidation, the system size can become
impractical.39
The manufacturers of the catalytic oxidizers and of the gas/solid
reactor claim EO destruction efficiencies greater than 99.9 percent and
offer the results of third-party tests to support these claims.35»1+0»1*1
However, test data on the efficiencies of the control units operating
under conditions (i.e., low concentrations and high flow rates) that are
typical of aeration room exhaust streams are not available.
Generally, the control units are tested by sending the control device
a stream of EO with a much higher concentration (e.g., 100 to
140,000 ppmv) than that associated with normal operating
conditions. »l|0>ltl The results of these tests are the efficiencies
reported by the manufacturers. However, these test results are
inconclusive because (1) it has not been demonstrated whether the control
4-18
-------
units perform at the same efficiencies under normal operating conditions
(i.e., very low inlet concentrations) as during test conditions (i.e.,
controlled flow, high concentration); (2) EPA has not verified the
available test data; (3) there has not been an EPA-sponsored test of these
control devices with aeration room emissions; and (4) a test reference
method has not been developed (but is being developed) to evaluate the
efficiencies of these control devices with aeration room emissions.
The lower detection limits of most analytical procedures that are
used to measure EO concentrations are approximately 0.5 ppmv to 1 ppmv,
which is equal to or greater than the EO concentrations in many aeration
rooms. Although one testing laboratory reportedly used a method with a
detection limit less than 0.1 ppmv, the test data have not been verified
by EPA, and it is unknown whether this method can be applied to high flow
rates. (The flow rate tested was 14 m3/min [500 ft3/min].)M Also,
because of the reactivity of EO, the validity of detection limits below
1 ppmv, and particularly below 0.5 ppmv, is questionable/2 Because the
detection Limits of the analytical methods (in ppmv) are so close to the
room concentrations, testing under normal operating conditions may yield
an efficiency that only can be calculated to be equal to 50 percent or
less.
Three possible techniques for reducing EO emissions from aeration
rooms are (1) recirculate the air from the aeration room control device to
the aeration room, (2) replace the warehouse-type aeration rooms with
smaller, heated aeration cells, or (3) modify the evacuation and air wash
phase of the sterilization cycle. The first two techniques increase the
EO concentration in the aeration room and lower the flow rate, which makes
both control of the emissions and testing of the control efficiency more
practical. The third alternative lowers the EO emissions from the
aeration room by decreasing the residual EO in the product prior to
aeration. These techniques are discussed in more detail below.
The first alternative refers to routing the aeration room air through
an emission control device and back to the aeration room. A small amount
of makeup air is added to the control device exit stream to regulate the
room temperature. This practice increases the room temperature and,
therefore, increases the diffusion rate of EO from the product, producing
4-19
-------
a higher EO concentration in the room. (Worker exposure and compliance
with the OSHA standards will need to be considered if frequent worker
access to the room is required.) Catalytic oxidation and the gas/solid
reactor are more applicable to the increased EO concentrations and
decreased flow rates associated with this process than to typical aeration
room emissions. (In addition, increasing the room temperature reduces the
energy costs of preheating the inlet stream to the catalytic oxidizer.)
Hydrolysis, thermal oxidation, and condensation/reclamation are not
applicable because the EO concentrations are too low (<20 ppmv) for these
techniques to be practicable. Because the room air is recirculated and
not vented to the atmosphere, this technique eliminates practically all
aeration room emissions; only a small amount of the emissions from the
control device are vented to allow fresh makeup air to enter the room.
This practice of recirculating the aeration room air is used by two of the
203 commercial sterilization facilities represented in the EPA data
base. The aeration rooms at these two commercial facilities are each
approximately 140 m3 (5,000 ft3) in volume.31 These 2 facilities
manufacture synthetic rubber products, which retain a large amount of
residual EO and, therefore, require a longer aeration period than the
majority of products that are sterilized with EO. The facilities
installed the recirculating system to decrease the aeration time and the
residual EO concentrations in the products."*3 A catalytic oxidation
system is used to control the EO emissions and to provide hot air to heat
the room.1*
Another alternative is to replace the large, warehouse-type aeration
rooms with smaller (70 m3 [2,500 ft3] or less), heated aeration cells and
control the emissions from the cell. In this process, instead of storing
the sterile products in a warehouse and aerating at normal room
temperatures, the products are aerated in heated (>43°C [110°F]) insulated
cellular units. The emissions from these cells can be controlled by
catalytic oxidation or the gas/solid reactor system. Emissions from the
control unit can be recirculated to the aeration cell or vented to the
atmosphere. The cells can be filled approximately 40 to 75 percent full
and still allow sufficient air space for off -gassing. "»'"' The cell is
heated either with supplemental heat or hot air from the control device if
4-20
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catalytic oxidation is used. Several commercial sterilization facilities,
particularly contractors, are aerating at least part of the sterile
products in heated, cellular units.3t'3a Structures used for aeration
include insulated shipping containers, modified walk-in coolers (which are
heated instead of cooled), and manufactured units designed specifically
for the heated aeration process."*5"1*7 Most of these facilities have
installed these units to reduce the aeration time or the residual EO
concentration in the products. The heated cells are similar to the first
technique described above (i.e., the practice of recirculating the
aeration room air) in that the EO concentration in the cell will increase
due to elevated temperature.
Another strategy for reducing aeration room emissions is modifying
the evacuation/air wash phase of the sterilization cycle. Residual EO in
the product can be reduced by performing additional sterilization chamber
purges. However, this procedure does require additional time in the
sterilizer and could affect plant operating schedules. The potential
reduction in residual EO with evacuation-phase modifications is product
dependent. Results from tests performed at one facility that fumigates
spices showed an average reduction in residual EO of 26 percent for four
different spices following evacuation-phase modifications.19 Some
facilities aerate in the sterilizer, with or without cycle
modifications. Aeration emissions from the sterilizer can be sent to
the sterilizer control device. However, the removal efficiencies of the
hydrolysis techniques have not been determined for the low inlet
concentrations associated with aeration emissions. Also,
condensation/reclamation would not be practicable for controlling these
low concentrations.
4.1.3.2 Aeration Chambers. Many hospitals and some commercial
sterilization facilities use aeration chambers instead of aeration
rooms. These chambers are similar in appearance and size (<1 m3 [40 ft3])
to the sterilization chambers used at hospitals. However, the flow rate
is much lower from the chambers than from aeration rooms. Therefore,
catalytic oxidation and the gas/solid reactor are applicable to the
control of EO emissions from aeration chambers. Several hospitals and
small commercial sterilization facilities use catalytic oxidation or the
4-21
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gas/solid reactor system to control aeration chamber emissions, and at
least one commercial sterilization facility uses an acid-water scrubber to
control these emissions.9'10'31 However, as stated in Section 4.1.3.1,
the control efficiencies of these techniques have not been determined for
the low concentrations from aeration processes.
4.2 OTHER STERILIZATION PROCESSES
There are no demonstrated EO emission control devices for single-item
sterilization processes or for portable fumigation units. The problems
associated with controlling EO emissions from these sources are discussed
below.
4.2.1 Single-Item Sterilization
Single-item sterilization systems do not use a chamber evacuated with
a vacuum pump. (See Section 3.2.2 for a description of single-item
sterilization.) Instead, the EO is allowed to diffuse from products while
they are inside an aeration room or cabinet. The EO from facilities using
single-item sterilization systems is, therefore, emitted from one major
source, the aeration room/cabinet vent. Because there is no evacuation
phase, the EO concentration in the gas stream from single-item
sterilization systems is higher than the concentration of EO in aeration
rooms. However, the concentration is sufficiently low such that catalytic
oxidation or the gas/solid reactor system may be viable control options.
4.2.2 Fumigation with Portable Units
Because of problems with transporting an emission control device,
there are no practical controls of EO emissions from the portable units
operated by State departments of agriculture to fumigate beehives.
However, one State Department of Agriculture is working on the development
of an acid-water scrubber for portable fumigation units.3
4.3 ALTERNATIVES TO EO STERILIZATION
In some cases, radiation sterilization can replace EO sterilization.
Radiation sterilization is used for about half of the products sterilized
u a
in the U.S. However, not all products can be sterilized with radiation;
plastics can become broken, discolored, or malodorous, and Teflon® and
acetyl delrin are damaged by radiation.<+a»'19 According to industry
representatives, most of the commonly used plastics have been or are in
the process of being reformulated to withstand radiation.50'51 Therefore,
the potential use of this alternative will probably increase.
4-22
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There are several chemical alternatives to EO sterilization (e.g.,
chlorine dioxide, gas plasma, hydrogen peroxide, and ozone). However,
these chemicals do not necessarily offer environmental improvements over
EO. Other alternatives include X-ray (a new, developing technology), deep
freezing (museum and spice industry), and increased use of disposable
medical items in hospitals. However, none of these alternatives can
replace the use of EO in all applications.
4.4 RETROFIT CONSIDERATIONS
All of the control devices discussed above can be retrofitted to
existing EO bulk sterilization chambers. However, the use of flares in
urban areas is prohibited because of safety hazards. There are no
retrofit problems associated with the replacement of once-through vacuum
pumps with closed-loop recirculating vacuum pumps for control of drain
emissions.
4.5 IMPACTS OF A CFC REGULATION ON EO EMISSION CONTROLS
Federal regulations for stratospheric ozone-depleting
chlorofluorocarbons (CFC's) have been developed under EPA's Stratospheric
Ozone Protection Program (SOPP). The use of CFC's in sterilant gases is
one of the source categories subject to these regulations. The most
popular sterilant gas mixture, 12/88, contains 88 percent by weight
dichlorodifluoromethane (CFC-12), which is an ozone-depleting CFC. Nearly
all hospitals and 75 percent of the 203 commercial sterilization
facilities represented in the EPA data base use 12/88 at least part of the
time. » The requirements of a CFC regulation would not affect the
ability of a sterilization facility to control EO emissions. The
explosion-proof condensation/reclamation system discussed above recovers
CFC-12 emissions in addition to EO emissions. However, if this control
device is used, add-on controls (e.g., catalytic oxidation or a small
scrubber) need to be considered for the EO remaining in the chamber after
the reclamation cycle is complete. Also, a nonexplosion-proof
condensation/reclamation system that recovers only CFC-12 could follow the
acid-water scrubbing of EO to ethylene glycol.52 Some facilities may
switch to sterilant gases that do not contain CFC-12 (such as 10/90 and
pure EO), in which case, the EO control techniques discussed above still
would be applicable.
4-23
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4.6 REFERENCES FOR CHAPTER 4
1. Safe-Cell™ product brochure. Attachment to letter from Kruse, R.,
Advanced Air Technologies, Inc., to Farmer, J., EPA. May 31, 1988.
2. Letter and enclosures from J. Jorkasky, Health Industry
Manufacturer's Association (HIMA), to D. Markwordt, EPArCPB.
February 21, 1986. Survey responses from HIMA members.
3. Responses to July 1986 Section 114 information request regarding the
use of ethylene oxide by miscellaneous sterilization and fumigation
facilities.
4. Memorandum. Srebro, S., MRI, to Markwordt, D., EPA/CPB. Examination
of Ethylene Oxide Control Efficiencies. Attachment to Effect on the
Maximum Individual Risk from an Increase in the Ethylene Oxide
Removal Efficiencies. October 5, 1988.
5. Organic Chemical Manufacturing Volume 4: Combustion Control
Devices. EPA-450/3-80-026. December 1980. Control Device
Evaluation: Flares and the Use of Emissions as Fuels. p.III-2.
6. Ethylene Oxide Product Information Bulletin. Union Carbide Corp.,
Ethylene Oxide/Glycol Division. 1983.
7. Letter from Buonicore, A., Chemrox, Inc., to Markwordt, D.,
EPA:CPB. August 27, 1984. Comments on sources of ethylene oxide
emissions draft report.
8. Conway, R., Waggy, G., Spiegel, M., and Berglund, R. Environmental
Fate and Effects of Ethylene Oxide. Environmental Science and
Technology. 17(2):107-112. 1983.
9. Telecon. Nicholson, R., MRI, with Olson, C., Donaldson Company,
Inc. May 12, 1988 and June 13, 1988. Discussion about applicability
of catalytic oxidation to large aeration rooms and location of
facilities using the EtO Abater™.
10. Contact report. Srebro, S., MRI, with Meo, D., DM3 Incorporated.
December 9, 1988.
11. Telecon. Nicholson, R., MRI, with Kruse, R., Advanced Air
Technologies, Inc. June 14, 1988. Discussion about the Safe-Cell™
gas/solid reactor.
12. Ethylene Oxide Control Technology Development for Hospital
Sterilizers. Meiners, A., MRI. EPA-600/2-88-028. May 1988.
13. Questionnaire for Croll-Reynolds Ethylene Oxide Scrubber—Customer
Specifications. Droll-Reynolds Company. Westfield, New Jersey.
October 1985.
4-24
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14. Telecon. Newton, 0., MRI, with Urban, T., Chemrox, Inc.
February 13, 1986. Discussion about disposal of scrubber liquor
containing ethylene glycol.
15. Newsletter about EO control. Chemrox, Inc., Bridgeport, Connecticut
Volume 1, No. 1. October 1983.
16. Certification Testing Report. BCA Project No. 85-260. Chemrox Inc.
Bridgeport, Connecticut. October 29, 1985.
17. Letter from Desai, P., Chemrox, Inc., to Wyatt, S., EPA:CPB.
September 17, 1987. Comments on draft BID Chapter 4 for ethylene
oxide NESHAP.
18. "Sampling/Analytical Method Evaluation for Ethylene Oxide Emission
and Control Unit Efficiency Determinations." Final Report. Radian
Corporation, Research Triangle Park, North Carolina. April 5, 1988.
19. Desai, P. Performance Test Report: DEOXX™ Ethylene Oxide
Detoxification System. Chemrox Project No. 85-260. October 1985.
20. Memorandum. Srebro, S., MRI, to Markwordt, D., EPA:CPB. Capital
cost, annualized cost, and cost effectiveness of reducing ethylene
oxide emissions at commercial sterilization facilities. March 20
1987. 80 p.
21. Product Data Sheet. Environmental Tectonics Corporation. Enclosure
to letter from Peters, J., Environmental Tectonics Corporation, to
Nicholson, B., MRI, June 10, 1987.
22. Meeting Minutes. Beall, C., MRI, to Markwordt, D., EPA:CPB. Damas
Corp. and Johnson & Johnson. April 30, 1986. 9 p.
23. Letter and attachments from Smith, D., Damas Corp., to Wyatt, S.,
EPA:CPB. September 21, 1987. -Comments on draft BID Chapter 4 for
ethylene oxide NESHAP.
24. Telecon. Srebro, S., MRI, with Hoffman, J., Med-Chem Reclamation,
Inc. (formerly B&D Industries). March 6, 1989. Discussion about
recovery of ethylene glycol from ethylene oxide scrubbing liquor.
25. Telecon. Srebro, S., MRI, with Duvow, J., Chemstreams,
Incorporated. March 16, 1989. Discussion about recovery of ethylene
glycol from ethylene oxide scrubbing liquor.
26. Telecon. Srebro, S., MRI, with Dalton, K., High Valley Chemicals.
March 16, 1989. Discussion about recovery of ethylene glycol from
ethylene oxide scrubbing liquor.
27. Letter and attachments from Smith, S., John Zink Company, to
Coronna, B., MRI. October 3, 1986. Information about the John Zink
EO flare.
4-25
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28. Telecon. Soltis, V., MRI, with Duck, 3., John link Company. July 8,
1987. Discussion about EO sterilant gas mixtures and the use of
flares.
29. Telecon. Srebro, S., MRI, with Meo, D., DM3 Incorporated.
January 13, 1989. Discussion about CATCON catalytic oxidation
systems.
30. Telecon. Srebro, S., MRI, with Ames, G., South Coast Air Quality
Management District. March 10, 1989. Discussion about hospital
sterilizers that use air ejectors to send emissions to a catalytic
oxidizer.
31. Responses to July 1988 information collection request regarding
chamber operating parameters, current controls, vacuum pumps, and
aeration rooms.
32. Letter and attachments from Olson, C., Donaldson Company, Inc., to
Markwordt, D., EPA/CPB. March 21, 1988. Test data for EtO Abater™
for sterilizer chamber emissions.
33. Telecon. Srebro, S., MRI, with Meo, D., DM3 Incorporated.
December 2, 1988. Discussion about the CATCON catalytic oxidation
systems.
34. Memorandum. BeaTl, C., MRI, to Markwordt, D., EPArCPB. Trip
Report: Sterilization Services of Tennessee, Memphis, Tennessee, on
March 18, 1986.
35. Letter and attachment from Hammer, D., Consulting Engineer, Advanced
Air Technologies, to Markwordt, D., EPA/CPB. June 22, 1988.
Transmitting test data for the Safe-Cell™ system.
36. Buonicore, A. In-Plant Programs to Reduce Ethylene Oxide Worker
Exposure Levels. Chemrox, Inc., Bridgeport, Connecticut. August
1984.
37. EO-VAC" Closed Loop Vacuum Product Information Sheet. Chemrox, Inc.
Bridgeport, Connecticut. May 1987.
38. Letter and attachments from Meo, D., DM3 Incorporated, to Srebro, S.,
MRI. January 13, 1989. Transmitting information about the CATCON
system.
39. Letter and attachments from Kruse, R., Advanced Air Technologies, to
Nicholson, R., MRI. June 15, 1988. Transmitting information about
Safe-Cell" system.
40. Letter and attachments from Olson, C., Donaldson Company, to
Srebro, S., MRI. November 9, 1988. Transmitting test data for the
EtO Abator".
4-26
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41. "Report of Air Pollution Source Testing Conducted at lolab
Corporation." Engineering Science, Incorporated, Pasadena,
California. Seotember 27, 1988. Attachment to letter from Meo, D.,
DM3, Incorporated, to Srebro, S., MRI. December 16, 1988.
42. Analytical Chemistry. Volume 60. 1988. pp. 24-54 to 24-60.
43. Telecon. Shine, B., MRI, with Cutright, L., Seamless Hospital
Products. October 20, 1988. Discussion about the catalytic oxidizer
used to control aeration room emissions at Seamless.
44. Telecon. Friedman, E., MRI, with Shumway, R., Medronic,
Incorporated. January 18, 1989. Discussion about the heated
aeration cells at Medronic.
45. Memorandum. Srebro, S., MRI, to Markwordt, D., EPA/CPB. Site
visit: Medtronic, Incorporated, Anaheim, California, on December 9
1988.
46. Memorandum. Srebro, S., MRI, to Markwordt, D., EPA/CPB. Site
visit: lolab, Incorporated, Claremont, California, on December 9,
1988.
47. Product brochure. Chemrox, Incorporated. Hot Cell™ heated aeration
unit.
48. Telecon. Soltis V., MRI, with Jorkasky, J., Health Industry
Manufacturers Association. March 2, 1987. Discussion about trends
in the sterilization industry.
49. Telecon. Beall, C., MRI, with Chin, A., Radiation Sterilizers,
Inc. February 22, 1986. Discussion about gamma radiation.
50. "Cobalt-60 Growth from 1978 to 1988." Chin, A., Radiation
Sterilizers, Incorporated. Presentation at the Health Industry
Manufacturers' Association (HIMA) "Sterilization in the 1990's"
Conference in Washington, D.C., on October 31, 1988.,
51. "Radiation and Plastic: Friend or Foe." Apostolou, S., POLY-
FOCUS. Presentation at HIMA conference on October 31, 1988.
52. Telecon. Srebro, S., with Desai, P., Chemrox, Incorporated.
January 20, 1987. Discussion about the FREOXX™ CFC-12 reclamation
system.
4-27
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5. EMISSION CONTROL COSTS
5.1 INTRODUCTION
This chapter presents a summary of the methodology to develop
emission control cost estimates. Costs presented in this chapter are in
December 1984 dollars. A method for estimating EO emission control costs
at commercial sterilization facilities is presented in Section 5.2.
Limited cost information has been obtained about emission controls for
hospital sterilizers, single-item sterilization systems, and aeration
rooms; these costs are discussed in Sections 5.3 through 5.5,
respectively.
5.2 CONTROL COSTS FOR COMMERCIAL STERILIZATION FACILITIES
This section describes a method for estimating emission control costs
for sterilizer vent(s) and the vacuum pump drain at commercial sterilization
facilities. Acid hydrolysis (i.e., acid-water scrubbing) was chosen as the
bas-is for the costing procedure because that control technique currently is
practiced at several commercial sterilization facilities and has been
demonstrated at both small and large commercial facilities. A detailed
review of the available test data indicated that 99.0 percent is the maximum
EO removal efficiency that acid hydrolysis techniques can achieve on a
continuous basis.1 Therefore, 99.0 percent was used to calculate the
emission reductions.
The costing procedure presented in this section has been used to
develop emissions control costs for the 203 commercial sterilization
facilities represented in the EPA data base.2 (See Section 3.1 of this
report for a description of how the data base was developed.) The results
of this cost analysis for three actual commercial sterilization facilities
are presented in Table 5-1. Detailed sample calculations for another
commercial sterilization facility are given in Appendix B.
5.2.1 Description of Components Costed
The following components were costed: (1) an acid-water scrubber,
(2) a water-sealed vacuum pump with closed-loop recirculation for each
sterilizer, (3) piping for manifolding all chambers at a facility to one
scrubber, (4) operating materials (i.e., chemicals and chlorine filters),
(5) scrubber waste disposal, and (6) labor.
5-1
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Scrubber prices are listed in Table 5-2. The capital costs of the
piping system for manifolding and the installed cost of the vacuum pump are
presented in Tables 5-3 and 5-4. The costs of operating materials, as well
as the shipping charges used for computing disposal costs for the spent
scrubber solution, are presented in Table 5-5.2
Costs reported in Tables 5-2 through 5-5 are in fourth quarter 1984
dollars. The prices for the scrubbers, vacuum pump, chlorine filters, and
chemicals were obtained from the manufacturer and suppliers and were
originally in 1986 dollars. These prices were converted to fourth quarter
1984 dollars using the CE Plant Cost Index (for the equipment) and the
Current Business Indicators (for the chemicals) in Chemical
3 '* ~~~~~~~~~~
Engineering. ' The labor costs were calculated from the Economics
Assessment Branch (EAB/EPA) control cost manual and from the CE Plant Cost
•* 5
Index. » The indices used and the conversion factors obtained are reported
in Appendix B.
5.2.2 General Assumptions
Chamber volume was used as the basis for scrubber sizing. The rela-
tionship of chamber volume to scrubber size is presented in Table 5-2.2
If a facility has three or more sterilization chambers, the scrubber
costed was chosen based on the sum of the volumes of the two largest
chambers at that facility. This methodology simulates the cost of
controlling emissions from a facility if two chambers at that facility were
to be evacuated simultaneously. If a facility has two chambers, the
scrubber was selected based on the volume of the larger chamber. For
facilities with two chambers, it was assumed that the sterilization cycles
could be staggered so that the chambers would not be evacuated
simultaneously.2
For the purposes of this cost analysis, it was assumed that the
ethylene glycol would be accepted by a recovery facility on a no cost/no
credit basis, except for shipping charges. Therefore, the disposal cost for
the aqueous ethylene glycol solution produced by the acid-water scrubbers
was computed as the cost .to ship the solution, either in 55-gallon drums or
in a tank truck, depending on quantity, to a recovery facility.
Transportation costs were calculated by assuming that commercial
sterilization facilities are within 1,000 miles of one of the three known
5-2
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recovery facilities.2 However, these disposal costs may not be applicable
to all sterilization facilities. If a recovery facility is not available to
accept the liquor, it may be necessary to neutralize the scrubbing liquor
and then have it hauled to a landfill or incinerator, which may increase the
waste disposal costs.
5.2.3 Capital Costs
The fixed capital costs for a particular facility represent the initial
investment and installation charges for control equipment. The cost data
presented in Table 5-6 were used to calculate capital cost estimates for
each of the facilities.2
5.2.4 Annualized Costs
Annualized costs for a particular facility represent direct operating
costs such as labor costs, cost of materials, and disposal costs, as well as
indirect operating costs such as overhead charges, tax/insurance charges,
and capital recovery costs. The cost data presented in Table 5-7 were used
to estimate plant-specific annualized costs.2 .
5.3 CONTROL COSTS FOR HOSPITAL STERILIZATION CHAMBERS
Detailed cost estimates have not been developed for EO emission
controls at hospitals. Only a small percentage of hospitals control EO
emissions to the atmosphere. Emission controls used at hospitals include
acid-water hydrolysis, catalytic oxidation, and the gas/solid reactor system
discussed in Section 4.1.1.4 of this report.6'9
Because only a few control devices are in place at hospitals, the cost
data available are limited and, therefore, should be used cautiously.
Table 5-8 presents a range of the approximate costs of using catalytic
oxidation to control EO emissions from hospitals. The capital costs and
annual operating costs for catalytic oxidation were obtained from two
hospitals.10 Additional control cost estimates for hospitals have been
obtained from vendors and are given in Appendix C.
5.4 CONTROL COSTS FOR OTHER STERILIZATION SYSTEMS
There are no demonstrated EO emission control devices for single-item
sterilization processes or for portable fumigation units. Therefore,
emission cost estimates have not been developed for these processes.
However, the EO concentration and flow rate from single-item sterilization
units is low enough that catalytic oxidation or the gas/solid reactor system
5-3
-------
may be viable control options. See Appendix C for vendor-supplied cost
estimates for these control devices.
5.5 CONTROL COSTS FOR AERATION ROOMS
The potential control of aeration emissions is being evaluated by EPA,
and the preliminary cost analysis should be available by June 1989.
Catalytic oxidation and the gas/solid reactor system may be applicable to
the control of aeration emissions particularly from aeration chambers and
the heated, cellular structures to which some facilities are switching. See
Appendix C for vendor-supplied cost estimates for catalytic oxidation and
the gas/solid reactor system.
5-4
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TABLE 5-1. CONTROL COSTS FOR ACID HYDROLYSIS* b
Model
plant
Small d
Medium6
Largef
Total
sterilizer
volume,,
m3 (ft5)
2.8
(100)
28
(1,000)
168
(6,000)
Annual
EO use,
Mg
(lb/1,000)
0.18
(0.39)
3.9
(8.7)
109
(240)
Capital
costs, $
76,000
160,000
291,000
Annuali zed
costs, $
21,200
40,800
117,000
Annual emis-
sion reduc-
tion, Mg
(lb/l,000)c
0.17
(0.37)
3.7
(8.2)
102
(226)
These cost estimates are not applicable to hospitals because the acid-
water scrubbers costed are not designed for the low flowrates from the
.vacuum pumps on hospital sterilizers.
See Appendix B for the methodology used to calculate these control costs,
"-Calculated as (0.99)x(0.95)(EO use). Five percent of the EO use is
assumed to be retained in the product after sterilization and emitted
.from the aeration room, which is assumed to be uncontrolled.
The small model plant has one chamber and uses 12/88 (EO/CFC-12).
Therefore, a model 100 scrubber (see Table 5-2) was chosen as the basis
for the calculations.
The medium model plant has one chamber and uses 12/88 gas. Therefore, a
fmodel 400 scrubber was chosen as the basis for the calculations.
The large model plant has seven chambers and uses 100 percent EO. The
sum of the volumes of the two largest chambers is 2,000 ft . Therefore,
a model 500 scrubber (with explosion-proof valves) was chosen as the
basis for the calculations.
5-5
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en
i
en
TABLE 5-2. COST OF DAMAS SCRUBBER MODELS (F.O.B.)1
(4th Quarter 1984 Dollars)
Model
No.
100
200
300
400
500
600
a
Chamber 0
size, m3 (ft3)3
<11.3 (<400)
11.3 to 17.0 (400 to 600)
17.0 to 22.7 (600 to 800)
22.7 to 45.3 (800 to 1,600)
45.3 to 56.6 (1,600 to 2,000)
>56.6 (>2,000)
Conversion capacity
of scrubber,
kg (Ib) of EO
908 (2,000)
1,816 (4,000)
2,724 (6,000)
3,632 (8,000)
4,540 (10,000)
5,448 (12,000)
Automated
scrubber
cost, $
47,250
68,250
89,250
99,750
141,750
157,500
Cost of explosion-
proof valves
for scrubber, $b
12,180
13,195
14,210
15,225
17,255
18,270
The size of sterilization chamber that can be served by the model number, assuming the smallest
appropriate vacuum pump 1s used.
'Explosion-proof valves are necessary If the sterilization chamber that is vented to the scrubber uses a
gas mixture greater than 20 percent by weight EO.
-------
TABLE 5-3. INCREMENTAL CAPITAL COST$ OF MANIFOLDING
STERILIZATION CHAMBERS1
Cost,
Item 1984 $
Opening in explosion-proof wall*
Adjustable sheetmetal sleeve 2b
Labor costs at $18.05/hour 93
Overhead costs at $8.35/hour 43
Drill holes for pipe hangersc
Labor costs at $19.40/hour 146
Overhead costs at $15.06/hour 113
P1p1ngd
100 ft, 2 in. diameter, 40 standard carbon steel pipe 240?
90° elbows, 3 at $4.19 13b
Tee with full-size outlet 14b
Swing check valve 350b
Bolts and gaskets, two sets at $6.76 14b
Pipe hangers, 1 carton of 50 hangers 140°
Labor costs at $20.50/hour 576
Overhead costs at $12.71/hour 357
Total installed cost for piping system
Total direct costs6 1,588
Total indirect costs:
Overhead costs 513
Administration9 159
Taxes . 39
Total installed cost1 ' 2,299
Total installed cost for recirculatinq vacuum pump 4,935
TOTAL CAPITAL COST 7j234
j*Requires 5.15 labor-hours.
"Equipment cost.
^Requires 7.5 labor-hours.
^Requires 28 labor-hours.
-Sum of all labor and equipment costs.
Sum of all overhead costs.
'Ten percent of total direct costs.
.Five percent of total equipment costs.
(Total direct costs)+(total indirect costs).
5-7
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TABLE 5-4. CAPITAL COST OF CHECK VALVE FOR CHAMBER1
Cost item Cost, 1984 $
Swing check valve 350a
Installation costsb
Labor costs at $20.50/hour 23
Overhead costs at $12.71/hour 14
Total direct costs0 373
Administration: 10 percent of total direct costs 37
Taxes: 5 percent of equipment cost 18
Total indirect costsd 69
Total installed cost6 442
Annualized capital recovery costf 74
^Equipment cost.
.Requires 1.1 labor hours to install.
jjSum of all labor and equipment costs.
°Sum of overhead costs, taxes, and administration.
"(Total direct costs)+(total indirect costs).
rCalculated as 0.16275x(total installed cost), for an interest rate of
10 percent and a 10-year recovery period.
5-8
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TABLE 5-5. MISCELLANEOUS OPERATING COSTS1
Item description
Cost, 1984 $
Operating materials
1. 50 percent H2SOm electrolyte-grade
2. 50 percent NaOH, industrial grade:
<2 drums
3-9 drums
>9 drums
3. Chlorine filters:
Filter housing
Filter
Installation
Shipping charges for waste disposal
Weight of solution for disposal:
<42,000 Ib (drums)
>42,000 Ib (bulk)
0.069/lb
0.108/lb
0.0787/lb
0.0738/lb
41.50 each
15.00 each
20.00 each
0.096/lb
0.059/lb
5-9
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TABLE 5-6. DATA USED TO CALCULATE CONTROL EQUIPMENT CAPITAL COSTS1
(4th Quarter 1984 Dollars)
Item
Cost factor
Automated scrubber
Explosion-proof valves for scrubber
Chlorine filter house
Scrubber installation
Chlorine filter installation
Taxes
Freight
Vacuum pump(s)
Manifolding of chambers (includes
check valve)
($41.50 each)x(No. of tanks)c
50 percent of scrubber cost
($20.00)x(No. of tanks)0
5 percent of total equipment cost
5 percent of total equipment cost
$4,935 per pump
^Function of chamber size (see Table 5-2).
Explosion-proof valves are necessary if the chamber that is vented to the
scrubber uses a gas mixture greater than 20 percent (by weight) EO.
Number of scrubber tanks required = scrubber conversion capacity divided
.by the conversion capacity of one tank (2,000 pounds of EO).
°See Tables 5-3 and 5-4.
5-10
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TABLE 5-7. DATA USED TO CALCULATE CONTROL DEVICE ANNUALIZED COSTS1
(4th Quarter 1984 Dollars)
Item
Cost factor
Direct operating costs
Labor
Materials:
50 percent H2S04
50 percent NaOH
Chlorine filters
Taxes
Freight
Compressed air
Disposal of ethylene glycol
Indirect operating costs
Overhead
Property tax, Insurance,
and administration
Capital recovery costs
$3,177+($11.60)x(16 person-hours)x(No. of scrubber regenerations)* b
($0.069/lb)x(594 lb/drum)x(No. of drums required)
(Cost/lb)x(700 lb/drum)x(No. of drums required)
c d
c, e, f
» •
($15/filter)x(No. of tank regenerations)0 9
5 percent of materials cost
5 percent of materials cost
Oh
1
(O.S)x(labor costs)
4 percent of total capital costs
(0.16275)x(total capital costs)j
(continued)
-------
TABLE 5-7. (continued)
tn
aNumber of scrubber regenerations = amount of EO to be treated divided by the conversion capacity of the
.scrubber (See Table 5-2).
The $3.177 Is for visual Inspection of the system 15 minutes per shift. 3 shifts per day, 365 days per
year at 511.60/person-hour. It was assumed that each regeneration of the scrubber solution would
crequ1re two people at 8 person-hours each, Independent of scrubber size.
/Tnno °f S5rubber ^nks = scrubber conversion capacity divided by the conversion capacity of one tank
(<>,uoo pounds of EO). Number of tank regenerations = number of scrubber regenerations multiplied bv
.the number of scrubber tanks.
Each tank regeneration requires one 55-gallon drum of 50 percent H?SO/,.
Each tank regeneration requires 250 pounds of NaOH for neutralization.
Cost basis for 50 percent NaOH (350 pounds NaOH per drum):
If No. of drums >9, cost/lb = $0.0738
If No. of drums = 3 to 9, cost/lb = $0.0787
If No. of drums <2, cost/lb = $0.108
chlorine filter can dechlorlnate approximately 200 gallons (one tank) of H90; replace filter at
.each tank regeneration. *
Jhe cost of 10 seconds of In-house compressed air per cycle 1s considered negligible.
Un t cost of disposal was calculated by multiplying the total number of tank regenerations by the
"page B-3]* regeneration, approximately 4.845 Ib (see Example Calculation No. 3 1n Appendix B
If the total weight <42,000 Ib, disposal cost = (we1ght)x($0.096/lb).
If the total weight >42,000 Ib, disposal cost = (we1ght)x($0.059/lb).
JAssumes an Interest rate of 10 percent and a 10-year recovery period
-------
TABLE 5-8. HOSPITAL EMISSION CONTROL COSTS
10
Annual
Control device Capital costs, $a operating costs, $b
Catalytic oxidation 30,000-50,000 6,000-16,000
aTotal installed capital costs. (Does not include modifying
.vacuum pump)
Direct operating cost and annualized catalyst and prefilter
replacement.
5-13
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5.6 REFERENCES FOR CHAPTER 5
1. Memorandum. Srebro, S., MRI, to Markwordt, 0., EPA/CPB. Examination
of Ethylene Oxide Control Efficiencies. Attachment to Effect on the
Maximum Individual Risk from an Increase in the Ethylene Oxide Removal
Efficiencies. October 5, 1988.
2. Memorandum. Srebro, S., MRI, to Markwordt, D., EPA/CPB. Capital cost,
annualized cost, and cost effectiveness of reducing ethylene oxide
emissions at commercial sterilization facilities. March 20, 1987.
80 p.
3. Chemical Engineering. Economic Indicators. February 18, 1985. p. 7.
4. Chemical Engineering. Economic Indicators. June 23, 1986. p. 7.
5. Neveril, R., Capital and Operating Costs of Selected Air Pollution
Control Systems. GARD, Inc. Miles, Illinois. Publication
No. EPA-450/5-80-002. December 1978. p. 3-11, 12, 16.
6. Responses to July 1988 EPA information request regarding chamber
operating parameters, vacuum pumps, current controls, and aeration
rooms.
7. Telecon. Nicholson, R., MRI, with Olson, C., Donaldson Company, Inc.
May 12, 1988 and June 13, 1988. Discussion about applicability of
catalytic oxidation to large aeration rooms and location of facilities
using EtO Abaters™.
8. Contact report. Srebro, S., MRI, with Meo, D., DM3, Incorporated.
December 9, 1988.
9. Telecon. Nicholson, R., MRI, with Kruse, R., Advanced Air
Technologies, Inc. June 14, 1988. Discussion about Safe-Cell™
gas/solid reactor.
10. Ethylene Oxide Control Technology Development for Hospital
Sterilizers. Meiners, A., MRI. EPA 600/2-88-028. May 1988.
5-14
-------
-------
APPENDIX A.
FEDERAL AGENCY CONTACTS, CONTROL DEVICE VENDORS, AND
ETHYLENE GLYCOL RECOVERY COMPANIES
-------
-------
TABLE A-l. CONTACTS AT FEDERAL AGENCIES
Agency name and address
Food and Drug Administration
Division of Compliance
8757 Georgia Avenue
Silver Spring, Md. 20910
Occupational Safety and Health
Administration
200 Constitution Avenue
Washington, D.C. 20210
U. S. Environmental Protection Agency
U. S. Environmental Protection Agency
Global Change Program
401 M Street, S.W.
Washington, D.C. 20460
U. S. Environmental Protection Agency
Office of A1r Quality Planning and
Standards
Research Triangle Park, N.C. 27711
Item of concern
Sterility compliance
(e.g., switching
steMlants)
Worker exposure (e.g.,
aeration rooms)
Sterilant registration
(e.g., switching
sterllants)
Chlorofluorocarbon
regulations
Economics
Emission test method
Health risk assessment
Standards development
(EPA Lead Engineer)
Contact name
Phone
Virginia Chamberlain (301) 427-7194
Melody Sands
John Lee
Karla Perri
Tom Walton
John Margeson
(Office of Research
and Development
Nancy Pate
David Markwordt
(202) 523-9308
(703) 557-5339
(202) 475-7496
(919) 541-5311
(919) 541-2848
(919) 541-5347
(919) 541-0837
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TABLE A-2. CONTROL DEVICE MANUFACTURERS3
Company name and address
Control types
Emission source applicability
Advanced Air Technologies, Inc. Scruober
710 S. McMilIan Street
Owosso, Michigan 48867
(517) 723-2171
Chemrox, Incorporated
217 Long Hill Crossroads
SheI ton, Connecticut 06484
(203) 926-9081
CrolI-Reynolds
Post Office Box 668
Westfield, New Jersey 07091
(201) 232-4200
Oamas Corporation
8 RomanelIi Avenue
S. Hackensack, New Jersey 07606
(201) 489-0525
DM3, Incorporated
1530 E. Edinger Avenue
Santa Ana, CaIiforn i a 92705
(714) 543-1312
Donaldson Company, Inc.
Post Office Box 1299
Minneapolis, Minnesota 55440
(612) 887-3155
John Zink
4401 South Peoria Avenue
Post Office Box 702220
Tulsa, Oklahoma 74170
(918) 747-1371
Environmental Tectonics, Inc.
County Line Industrial Park
Southampton, Pennsylvania 18966
(215) 355-9100
Vacudyne, Inc.
375 E. Joe Orr Road
Chicago Heights, Illinois 60411
(312) 757-5200
Gas/sol id reactor
Scrubber
CFC reclamation system
(after EO removed)
Scrubber
Scrubber
Catalytic oxidation
Catalytic oxidation
Flare
Scrubber
EO reclamation system
(for use with 12/88)
Scrubber—vent (small and large
chambers)
Gas/solid reactor—vent (after
scrubbing); aeration chamber
or room; sterilizer door;
hood; si ngIe-itern ster iIi za-
tion units
Vent
Vent
Vent
Vent (low flows, small chambers)
Aeration chamber or room
Single-item sterilization units
Vent (low flows, small chambers)
Aeration chamber or room
Single-item sterilization units
Vent (large chambers; pure EO)
Vent
Vent (large chambers)
This information is provided for the convenience of the reader and does not imply product
endorsement by EPA.
A-2
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TABLE A-3. ETHYLENE GLYCOL RECOVERY COMPANIES3
Mr. Jerry Duvow
Chemstreams
3501 River Road
Matthews, North Carolina 28106
(704) 821-6727
Mr. Keven Dalton
High Valley Chemicals
1151 S. Redwood Road
Suite 105
Salt Lake City, Utah 74104
(801) 973-7966
Mr. John Hoffman
Med-Chem Reclamation, Inc. (formerly B&D Industries)
7900 N. Kolmar
Skokie, Illinois 60076
(312) 673-1441
aThis information is provided for the convenience of the
reader and does not imply product endorsement by EPA.
A-3
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APPENDIX B.
COST INDICES AND
SAMPLE COST CALCULATIONS
-------
COST INDICES AND CONVERSION FACTORS
The prices for the scrubbers, vacuum pump, chlorine fiHars, and
chemicals were obtained from the manufacturers and suppliers and were
originally in 1986 dollars. These prices were converted to 4th quarter
1984 dollars using the following indices from Chemical Engineering;
February 1986 October 1984:
Conversion
factor
CE Plant Cost Index
Scrubber
Vacuum pump
Explosion-proof valves
Chlorine filters
Current Business Indicators
319.2
418.6
377.1
344.1
335.1
413.1
382.9
334.7
1.05
0.987
1.015
0.98
Industrial chemicals
340.0
334.7
0.98
The labor costs were calculated using the Economics Assessment Branch
(OAQPS/EAB) Control Cost Manual and the annual CE Plant Cost Indices in
Chemical Engineering:
CE Plant Cost Index
1978
1984
Conversion factor
EAB Conrol Cost Manual'
Labor for calculations
218.8
322.7
1.47
$7.87/person-hour
$11.60/person-hour
B-l
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EXAMPLE CALCULATIONS FOR CONTROL COSTS"
Sterilization chambers at; the facility
Size, ft3
Gas type
EO USE, Ib
EO-EMIT, Ib
MEO-EMIT, Mg
EO-FAC, Ib
MEO-FAC, Mg
EO-TOT, Ib
MEO-TOT, Mg
CON-EM, Mg
REDUCE, Mg
No. 1
667
100
28,000
26,600
12.07
141,740
64.30
149,200
67.7
0.64
63.66
No. 2
667
100
28,000
26,600
12.07
No. 3
1,200
12/88
1,200
1,140
0.52
No. 4
1,334
100
46,000
43,700
19.82
No. 5
1,334
100
46,000
43,700
19.82
1. The size, gas type, and EO use are those for an actual commercial
sterilization facility represented in the EPA data base. (See Section 3.1
of this report for a description of how this data base was developed.)
The other values were calculated using the following assumptions:
a. EO-EMIT (Ib) = EO (Ib) emitted annually from an individual
sterilization chamber to the vacuum pump drain and to the atmosphere.
Sterilizer vent emissions and vacuum pump drain emissions were assumed to
be 50 percent and 45 percent of EO use (Ib), respectively. Residual EO in
the sterilized product prior to aeration was assumed to be 5 percent of
EO-USE (Ib). This 5 percent of the EO use is not included as part of
EO-EMIT (Ib).
b. MEO-EMIT (Mg EO) = EO-EMIT (lb)/2,204.6
c. EO-FAC (Ib) and MEO-FAC (Mg) are the amount of EO released
annually by the facility to the vacuum pump drain and to the atmosphere,
i.e., the sum of EO-EMIT and the sum of MEO-EMIT, respectively.
d. EO-TOT (Ib) is the total amount of EO (Ib) used annually by the
facility, i.e., the sum of EO use. MEO-TOT (Mg) = EO-TOT (lb)/2,204.6.
e. CON-EM (Mg) is the amount of EO that would be released annually
after control, i.e., MEO-TOT*(1-0.99)*0.95. Note that the 5 percent
residual EO in the sterilized product, which is later released from the
aeration room vent, is excluded from this calculated emission estimate.
B-2
-------
f. REDUCE (Nig) is the incremental amount of EO that would be reduced
if controls are implemented, i.e., (MEO-FAC)-(CON-EM).
2. For all calculations, a conversion efficiency of 99.0 percent was
assumed for the scrubber.
3. Each tank of the scrubber initially holds 198 gal H20 and
19.8 gal H2SO^. The manufacturer recommends that the tank be regenerated
(i.e., drained, rinsed, and refilled) after 2,000 Ib EO have been treated.
a. 19.8 gal H2SOk = 1.42 kg-mole H2SO^ (p = 1.834; MW = 98.08)
2NaOH+H2S0lt * Na2S
-------
6. Find number of regenerations of scrubber required per year:
a. Number of scrubber tanks = scrubber model/100 = 6 (scrubber
consists of modular tanks).
b. Conversion capacity of scrubber = (no. of tanks)x2,000 Ib =
12,000 Ib
c. Number of scrubber regenerations = EO-FAC (lb)/12,000, i.e., the
amount of EO (Ib) to be treated per year divided by the conversion
capacity of the scrubber.
141,700/12,000 » 11.81 scrubber regenerations/yr
d. Number of tank regenerations = (No. of scrubber
regenerations)/(No. of tanks per scrubber) = (11.81)x(6) = 70.87.
7. Cost of chlorine filter housing = (41.50)x(no. of tanks) =
$(41.50)x(6) = $249.
8. Installation costs:
a. Scrubber installation = (O.S)x(cost of scrubber) = $78,750
b. Chlorine filter housing installation = (20)x(no,. of tanks) = $120
9. The incremental capital costs of manifolding are presented in
Table 5-3 of this report.
10. Vacuum pumps. A closed-loop recirculating water vacuum pump is
required on each of the five chambers. The cost of modifying the first
vacuum pump is included in the cost of the scrubber; the cost of modifying
the other four vacuum pumps is $4,935 each.
11. Calculate direct operating costs:
a. Labor = 3,177+(ll'.60)x(16)x(no. of regenerations). The $3,177 is
for general inspection of the system 15 minutes/shift, 3 shifts/day,
365 days/yr at $11.60/person-hour. For the purposes of these cost
analyses, it was assumed that each regeneration of the scrubber would
require 2 people at 8 person-hours each, independent of scrubber size.
System inspection was also assumed to be independent of scrubber size.
b. Sulfuric acid (50 percent H2SOu-electrolyte grade).
Assumed: 1 55-gal drum of 50 percent H2SO\, i.e., 19.4 gal ^SO^, per
scrubber tank.
No. of drums required = No. of tank regenerations = (No. of scrubber
regenerations^ (No. of tanks per scrubber) = 70.87
Cost of acid = (no. of drums)x(594 lb/drum)x($0.069/lb)
B-4
-------
c. Caustic (50 percent NaOri-incustrial grade). First, the unit cost
of NaOH was calculated.
NaOH required per year = [No. of tank regenerations]x[NaOH (Ib)
required per tankj = 70.87x250 = 17,718 Ib/yr
Total drums/yr required by facility = total NaOH (lb)/350 Ib per
drum; total drums =50.6
If total drums >9, cost/1b = 0.0738
If total drums = 3 to 9, cost/1b = 0.0787
If total drums = <2, cost/lb = 0.108
Cost of caustic = (No. of drums)x(cost/1b)x(700 Ib/drum)
d. Cost of chlorine filters. Each filter can dechlorinate -200 gal
H20 (or 1 scrubber tank); replace at each scrubber regeneration.
Cost = (No. of scrubber regenerations^ (No. of tanks)x($15/filter)
e. Disposal. Unit cost of disposal was calculated by multiplying
the total number of tank regenerations by the weight of a tank at the time
of regeneration, including rinse water (see 3.f).
Total wt - 70.87x4,844 Ib/tank - 343,943 Ib/yr
If total wt <42,000 Ib, disposal cost = wt (lb)x($0.096/lb)
If total wt >42,000 Ib, disposal cost = wt (lb)x($0.059/lb)
f. Compressed air. The cost of 10 seconds of in-house air per cycle
was considered negligible and was not computed for these cost analyses.
12. The capital and annualized costs are reported in Table B-l.
B-5
-------
TABLE B-l. CAPITAL AND ANNUALIZED COSTS OF INSTALLING SCRUBBER1
(4th Quarter 1984 Dollars)
Item Cost
I. CAPITAL COSTSa
Installed equipment costs, 1984, $
Automated scrubber13 158,000
Explosion-proof valves for scrubber0 18,300
Chlorine filter house 249
Installation of scrubber6 79,000
Installation of chlorine filters 120
Taxes: 5 percent of equipment cost 8,850
Freight: 5fpercent of equipment cost 8,850
Vacuum pump 19,700
Manifolding of chambers (includes check valve)9 9,560
Total capital costs, 1984, $ 303,000
II. ANNUALIZED COSTS3
Direct operating costs, 1984, $
Laborh ' 5,370
Materials
50 percent H2SOJ 2,900
50 percent NaOhH. 2,620
Chlorine filters 1,060
Taxes: 5 percent of materials cost 329
Freight: 5 percent of materials cost 329
Compressed air1 0
Disposal of ethylene glycol"1 20,300
Indirect operating costs, 1984, $
Overhead: 0.80 x labor 4,300
Property tax, insurance, and administration" 12,100
Capital recovery costs 49,300
TOTAL ANNUALIZED COSTS, 1984, $ 98,600
III. COST EFFECTIVENESS
Reduce, Mg EO yr 63.66
Cost effectiveness, 1984, $/Mg EO 1,500
(continued)
8-6
-------
TABLE B-l. (continued)
*Costs rounded to three significant figures.
°8ased on total volume of two largest chambers.
JjOne set per scrubber at $18,300 each.
°0ne per tank; six tanks; $41.50 each.
-Fifty percent of scrubber cost.
The cost of the first vacuum pump is included in the installation cost of
the scrubber; therefore, cost is for remaining four pumps at $4,935 each.
ySee Table 5-4 of this report. Manifold four chambers at $2,300 each plus
$355 for a check valve for the first chamber.
"Labor was calculated for 0.25 person-hours/shift, 3 shifts/day,
365 days/year for system inspection and 16 person-hours for each
regeneration of the scrubber at $11.60/person-hour. No. of scrubber
regenerations = (annual EO use at facility)-*-(2,000)x(No. of tanks in
.scrubber).
^he cost of acid is calculated, (annual EO use at facility)*(2,000)x
.(594)x($0.069).
JThe cost of caustic is calculated, No. drum = (EO use/yr at
facilityH2,000)x(250)*(350). No. drum = 50.62; therefore, unit cost =
$0.0738. Total cost = (No.drums)x(700)x(0.0738).
Chlorine filter cost is (annual EO use at fac1l1ty)x(l5)+(2,000).
The cost of 10 seconds of house-supplied compressed air per cycle was
considered negligible.
Disposal cost is (annual EO use at facility)*(2,000)x(4,845)x(0.059).
"Calculated as 4 percent of total capital costs.
Calculated as (0.16275)x(total capital costs) for an interest rate of
10 percent and a 10-year recovery period.
B-7
-------
REFERENCES FOR APPENDIX B
1. Chemical Engineering. Economic Indicators. June 23, 1986. p. 7.
2. Chemical Engineering. Economic Indicators. February 18, 1985. p. 7.
3. Neveril, R., Capital and Operating Costs of Selected Air Pollution
Control Systems. 6ARD, Inc. Niles, Illinois. Publication
No. EPA-450/5-80-002. December 1978. p. 3-11, 12, 16.
4. Memorandum from Srebro, S., MRI, to Markwordt, D., EPA/CPB. March 20,
1987. Capital cost, annualized cost, and cost effectiveness of
reducing ethylene oxide emissions at commercial sterilization
facilities.
B-8
-------
APPENDIX C.
CONTROL DEVICE COSTS
(CATALYTIC OXIDATION AND GAS/SOLID REACTOR SYSTEM)
-------
TABLE C-l. CATALYTIC OXIDATION1
Flow rate,
m /mina (ft3/min)
1.4 (50)
3.5 (125)
14 (500)
28 (1,000)
84 (3,000)
168 (6,000)
252 (9,000)
336 (12,000)
Cost, $b c
15,000
23,000
37,000
60,000
97,000
140,000
192,000
240,000
The catalytic oxidation units are modular. The sizes listed
.are available currently. Larger sizes can be designed.
These costs are for catalytic oxidation systems capable of
handling sterilizer and aeration emissions simultaneously.
Costs were not provided for a system to handle only aeration
emissions.
Cost includes heat exchanger (70 percent heat recovery),
preheater, and prewiring. Installation and ducting costs are
facility-specific and were not provided.
C-l
-------
TABLE C-2. ACID-WATER SCRUBBER AND GAS/SOLID REACTOR SYSTEM2
Sterilizer volume Cost, $a b
<0.6 m3 (20 ft3) 30,000 to 35,000
0.6 to 1.2 m3 (20 to 40 ft3) 40,000 to 45,000
Two 0.8 m3 (30 ft3) sterilizers 45,000 to 50,000
One 2 m3 (72 ft3) sterilizer 50,000 to 55,000
dThese are "budget" costs for a complete two-stage system
(i.e., acid-water scrubber and the gas/solid reactor). Costs
.were not provided for the gas/solid reactor separately.
"Includes installation costs, wiring, and ductwork.
C-2
-------
REFERENCES FOR APPENDIX C
1. Telecon. Nicholson, R., MRI, with Olson, C., Donaldson Company,
Inc. May 12, 1988, and June 13, 1988. Discussion regarding the EtO
Abater™ catalytic oxidation system.
2. Letter from Kruse, R., Advanced Air Technologies, Inc., to
Nicholson, R., MRI. June 13, 1988. Transmitting information about
the Safe-Cell™ two-stage system.
C-3
-------
t
TECHNICAL REPORT DATA
?'.ssse reia insi*uciior.s on tne reverse oeiore co
i REPORT NO.
EPA-450/3-89-007
Z. RECIPIENT'S ACCESSION NO.
<*. TITLE AND SUBTITLE
Alternative Control Technology Document
Ethylene Oxide Sterilization/Fumigation Operations
5 REPORT DATE
! i larch 1989
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT MO
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Midwest Research Institute
401 Harrison Oaks Boulevard
Gary, North Carolina 27513
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-02-4379
12. SPONSORING AGENCY NAME AND ADDRESS
U. S. Environmental Protection Agency
Emission Standards Division
Office of Air Quality Planning and Standards
Research Triangle Park. North Carolina 27711
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
ESD Work Assignment Managers: David Markwordt (MD-13) (919) 341-0837
16. ABSTRACT
This document contains the data and methodology which EPA believes most accurately
describes alternative control technologies for ethylene oxide emissions from
steril-ization facilities.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS c. COSATI Held/Group
Ethylene Oxide
Ethylene Oxide Sterilization
Sterilization
Chlorofluorocarbons
Volatile Organic Compound (VOC) Emissions
M3. DISTRIBUTION STATEMENT
1 Release (Jnl imited.
19. SECURITY CLASS iTItis Reoorti
Unclassified
:i. NO. OF PAGES
00
;0. SECURI Tv CLASS i This
Unclassified
:2. PRICE
EPA Form 2220-1 (Rev. 4-77) Devious EDI TION i s OBSOLETE
-------
U S. Environmental Protection Agency
Region 5, Library (PL-12J)
77 West Jackson Boulevard, 12th Floor
Chicago, IL 60604-3590
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