&EPA
United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park. NC 27711
EPA-453/R-94-043a
July 1994
Air
Medical Waste Incinerators -
Background Information for
Proposed Standards and Guidelines:
Process Description Report
for New and Existing Facilities
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EPA-453/R-94-043a
Medical Waste Incinerators-Background Information for Proposed
Standards and Guidelines: Process Description Report for New and
Existing Facilities
July 1994
U. S. Environmental Protection Agency
Office of Air and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina
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DISCLAIMER
This report is issued by the Emission Standards Division,
Office of Air Quality Planning and Standards, U. S. Environmental
Protection Agency. It presents technical data of interest to a
limited number of readers. Mention of trade names and commercial
products is not intended to constitute endorsement or
recommendation for use. Copies of this report are available free
of charge to Federal employees, current contractors and grantees,
and nonprofit organizations--as supplies permit--from the Library
Services Office (MD-35), U. S. Environmental Protection Agency,
Research Triangle Park, North Carolina 27711 ( [919] 541-2777) or,
for a nominal fee, from the National Technical Information
Service, 5285 Port Royal Road, Springfield, Virginia 22161
( [703] 487-4650) .
iii
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iv
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TABLE OF CONTENTS
Page
LIST OF FIGURES iii
LIST OF TABLES iv
Abbreviations Used in this Report v
1.0 INTRODUCTION 1
1.1 REPORT DESCRIPTION . 1
1.2 PURPOSE OF THE REPORT 1
1.3 ORGANIZATION OF THE REPORT 1
2.0 OVERVIEW OF THE INCINERATION PROCESS FOR MWI'S .... 2
3.0 MEDICAL WASTE CHARACTERISTICS, SEGREGATION, STORAGE,
AND TRANSPORTATION . 6
3.1 CHARACTERISTICS OF MEDICAL WASTE COMPONENTS ... 6
3.2 MEDICAL WASTE SEGREGATION AND STORAGE PRACTICES . 7
3.3 MEDICAL WASTE TRANSPORTATION . 10
3.3.1 Transportation Within the Facility .... 10
3.3.2 Transportation of Untreated Medical
Waste to Offsite Locations 11
4.0 MEDICAL WASTE INCINERATION PROCESSES AND PROCESS
COMPONENTS . 12
4.1 CONTINUOUS-DUTY SYSTEMS 17
4.2 INTERMITTENT-DUTY SYSTEMS 22
4.3 BATCH-DUTY SYSTEMS . . 23
4.4 PATHOLOGICAL SYSTEMS 26
4.5 VARIATIONS IN MWI PROCESS COMPONENTS 29
4.5.1 Waste Loading and Feeding Mechanisms ... 29
4.5.2 Primary Chamber Variations . . , 31
4.5.3 Secondary Chamber Variations 38
4.5.4 Ash Removal and Handling 39
4.5.5 Energy Recovery 40
4.5.6 Bypass Stack 40
5.0 CHARACTERIZATION OF EMISSIONS 42
5.1 SOURCES OF EMISSIONS 43
5.1.1 Combustion Stack 43
5.1.2 Fugitive Emissions 45
5.2 FACTORS THAT AFFECT EMISSIONS . 46
5.2.1 Waste Characteristics 46
5.2.2 Incinerator Operating Characteristics . . 46
5.2.3 System Design 48
5.2.4, Startup and Shutdown Procedures 49
5.2.5 Operator Training 50
5.2.6 Preventive Maintenance ..... 50
5.3 EMISSION RATES 51
5.4 EXISTING EMISSION LIMITS 58
6.0 REFERENCES 73
v
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Figure 1.
Figure 2.
Figure 3.
Figure 4.
LIST OF FIGURES
Medical waste incineration process flow
diagram
Schematic of a medical waste incinerator . .
Schematic of a continuous-duty medical waste
incinerator with stepped hearth and automatic
ash removal
Schematic of a rotary kiln medical waste
incinerator
Page
13
18
20
21
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Schematic of an intermittent-duty medical
waste incinerator
Schematic of a single batch medical waste
incinerator
Retort hearth incinerator ....
Hopper/ram mechanical waste feed system ....
Schematic of a single-hearth, intermittent-
duty incinerator equipped with an ash ram . . .
Relationship between temperature and combustion
air levels ...
MWI with a waste heat recovery boiler and
bypass stack
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25
28
30
33
36
41
VI
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LIST OF TABLES
Page
TABLE 1. REGULATED MEDICAL WASTES 4
TABLE 2a. PHYSICAL CHARACTERISTICS OF MEDICAL WASTE
COMPONENTS (Metric Units) 8
TABLE 2b. PHYSICAL CHARACTERISTICS OF MEDICAL WASTE
COMPONENTS (English Units) 8
TABLE 3. CHARACTERISTICS OF THE BASIC TYPES OF MWI'S . . 14
TABLE 4. DESIGN CAPACITIES OF MWI'S 16
TABLE 5a. POST-COMBUSTION EMISSION RATES FOR MEDICAL WASTE
INCINERATORS (METRIC UNITS) 52
TABLE 5b. POST-COMBUSTION EMISSION RATES FOR MEDICAL WASTE
INCINERATORS (ENGLISH UNITS) 53
TABLE 5c. POST-COMBUSTION EMISSION RATES FOR MEDICAL WASTE
INCINERATORS (POUNDS PER YEAR) 54.
TABLE 6a. AVERAGE POST-COMBUSTION EMISSION RATES FOR MEDICAL
WASTE INCINERATORS (METRIC UNITS) 56
TABLE 6b. AVERAGE POST-COMBUSTION EMISSION RATES FOR MEDICAL
WASTE INCINERATORS (ENGLISH UNITS) 57
TABLE 7. STATE REQUIREMENTS FOR NEW MEDICAL WASTE
INCINERATORS 59
TABLE 8. STATE REQUIREMENTS FOR EXISTING MEDICAL .WASTE
INCINERATORS 66
VI1
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ABBREVIATIONS USED IN THIS REPORT
Btu British thermal unit
°C degrees centigrade
Cd cadmium
CDD's total dibenzo-p-dioxins (the sum of all isomers)
CDF's total dibenzofurans (the sum of all isomers)
CO carbon monoxide
C02 carbon dioxide
dscf dry standard cubic foot
EPA Environmental Protection Agency
°F degrees Fahrenheit
ft3 cubic feet
g gram
Hg mercury
hr hour
HC1 hydrogen chloride
H20 water
kg kilogram
kJ kilojoule
Ib pound
rcr cubic meter
MWI medical waste incinerator
MWTA Medical Waste Tracking Act
N2 (free) nitrogen
NOX nitrogen oxides
NSPS New Source Performance Standards
OSW Office of Solid Waste
Pb lead
PM particulate matter
ppmdv parts per million (dry volume)
PVC polyvinyl chloride
RCRA Resource Conservation and Recovery Act
sec second
S00 sulfur dioxide
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MEDICAL WASTE INCINERATOR FACILITY
PROCESS DESCRIPTION
1.0 INTRODUCTION
1.1 REPORT DESCRIPTION
This report describes the medical waste incineration process
starting from the point of generation of the waste and continuing
through the handling and transportation of the waste, the
combustion process, and the disposal of the ash. This document
is one of a series of reports written to provide background
information on the medical waste incineration industry, the
process description, emissions, emission control technology,
emission control costs, model plants, and environmental and
energy impacts for the medical waste incineration process.
1.2 PURPOSE OF THE REPORT
This report is designed to provide an overview of the
medical waste incineration process, describe the types of medical
waste incinerators (MWI's) and their components, and to discuss
the combustion process as it relates to MWI's. The report is
also intended to describe current practices associated with
medical waste generation, segregation, handling, and
transportation. Other specific purposes of the report include
identifying and characterizing the pollutants, as well as
describing the sources of emissions of these pollutants and the
factors that affect emissions of specific pollutants. The report
presents emission test data and existing State emission rate
limitations.
1.3 ORGANIZATION OF THE REPORT
Section 2.0 provides an overview of the incineration process
for MWI's and includes a description of the generic composition
of medical waste, as well as a brief discussion of what happens
during the combustion process. The physical and chemical
properties of medical waste and a description of how the waste is
segregated, stored, and transported are presented in Section 3.0.
The different types of MWI's and their associated components are
described in Section 4.0. Included in this section is a
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discussion of the variations in MWI components. The
characterization of stack and fugitive emissions is presented in
Section 5.0. This section includes discussions of sources of
emissions, factors that affect these emissions, and existing
emission limits (based on existing State requirements for MWI's).
2.0 OVERVIEW OF THE INCINERATION-PROCESS FOR MWI'S
Medical waste includes infectious and noninfectious wastes
generated by facilities such as hospitals, clinics, doctors' and
dentists' offices, nursing homes, veterinary establishments,
medical and research laboratories, and funeral homes.
The Resource Conservation and Recovery Act (RCRA), 1976, as
amended by the Medical Waste Tracking Act (MWTA), defines medical
waste as ". . . any solid waste which is generated in the
diagnosis, treatment, or immunization of human beings or animals,
in research pertaining thereto, or in production or testing of
biologicals." ("Biologicals" refers to preparations, such as
vaccines, that are made from living organisms.) Medical waste
is, in fact, a heterogeneous mixture of general refuse,
laboratory and pharmaceutical chemicals and containers, and
pathological waste. General refuse includes plastic materials,
paper products, glass, food wastes, and metal containers. These
materials may originate in administrative offices or cafeterias,
as well as in laboratories, hospital wards, or operating rooms.
Examples of laboratory and pharmaceutical chemical wastes include
alcohols, disinfectants, antineoplastic (chemotherapeutic)
agents, and materials containing heavy metals. Pathological
wastes include tissues, organs, body parts, blood, and body
fluids removed during surgery, autopsy, and biopsy.
Medical waste includes cultures and stocks of infectious
agents and associated biologicals, human blood and blood
products, pathological wastes, sharps, animal carcasses and
bedding, and waste from patients with highly communicable
diseases.1 The U.S. Environmental Protection Agency (EPA) Office
of Solid Waste (OSW) uses the term "regulated medical waste" to
denote the infectious component of medical waste. The categories
of regulated medical waste, as defined by OSW, are presented in
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Table 1. Other terms commonly used for the infectious component
of medical waste include biological, biomedical, biohazardous,
contaminated, red bag, pathological, and pathogenic waste. In
the United States, infectious wastes are required to be placed in
orange or red plastic bags or containers for handling. Often
these "red bag" wastes may contain noncontaminated general refuse
that has been combined with the infectious wastes.
Treatment by incineration, and disposal of the resultant ash
by landfilling, is an attractive option for managing medical
waste. A major benefit of incineration is the destruction of
pathogens (disease-causing agent's) , which occurs as a result of
the high temperatures achieved in MWI's. Another benefit is the
significant reduction of the weight and volume of waste material
to be landfilled; MWI's typically achieve better than 90 percent
burndown. In addition, converting waste to ash results in a more
aesthetically acceptable material. One of the major objectives
of incineration is to generate acceptable ash for land disposal.
(Acceptable ash is characterized by.pathogen destruction, low
volatile metals content, and a low percentage of organic matter.)
In some cases, incineration may provide-economic benefits through
waste heat recovery.
Medical waste is burned in incineration units under
controlled conditions to yield ash and combustion gases. The
combustion process is a complex combination of chemical reactions
that involve the rapid oxidation.of organic substances in the
waste and in auxiliary fuels. The goal of the process is to
achieve complete combustion of the organic materials and
destruction of pathogens-in the waste while minimizing the
formation and release of undesirable pollutants. How well the
process approaches complete combustion is determined by
temperature, time, turbulence, and mixing with oxygen.
Each organic substance in medical waste has a characteristic
minimum ignition temperature that must be attained or exceeded,
in the presence of oxygen, for combustion to occur. Above that
ignition temperature, heat is generated at a sufficient rate to
sustain combustion. Wastes containing high levels of moisture,
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TABLE 1. REGULATED MEDICAL WASTES'
Waste class
Description
1. Cultures and stocks
Cultures and stocks of infectious agents and associated biologicals,
including: cultures from medical and pathological laboratories; cultures
and stocks of infectious agents from research and industrial
laboratories; wastes from the production of biologicals; discarded live
and attenuated vaccines; and culture dishes and devices used to
transfer, inoculate, and mix cultures.
2. Pathological wastes
Human pathological wastes, including tissues, organs, and body parts
and body fluids that are removed during surgery or autopsy or other
medical procedures and specimens of body fluids and their containers.
3. Human blood and blood products
(a) Human blood; liquid waste; (b) products of blood; (c) items
saturated and/or dripping with human blood; or (d) items that were
saturated and/or dripping with human blood that are now caked with
dried human blood, including serum, plasma, and other blood
components and their containers, which were used or intended for use
in patient care, testing and laboratory analysis, or the development of
Pharmaceuticals. Intravenous bags are also included in this category.
4. Sharps
Sharps that have been used in animal or human patient care or
treatment or hi medical, research, or industrial laboratories, including
hypodermic needles, syringes (with or without the attached needle),
Pasteur pipettes, scalpel blades, blood vials, needles with attached
tubing, and culture dishes (regardless of presence of infectious agents).
Also included are other types of broken or unbroken glassware that
were in contact with infectious agents, such as used slides and cover
slips.
5. Animal wastes
Contaminated animal carcasses, body parts, and bedding of animals that
were known to have been exposed to infectious agents during research
(including research hi veterinary hospitals), production of biologicals,
or testing of pharmaceuticals.
6. Isolation Wastes
Biological waste and discarded materials contaminated with blood,
excretion, exudates, or secretions from humans who are isolated to
protect others from certain highly communicable diseases or from
isolated animals known to be infected with highly communicable
diseases.
7. Unused sharps
The following unused, discarded sharps: hypodermic needles, suture
needles, syringes, and scalpel blades.
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however, require additional supplemental heat input. A waste
constituent should reside in the high-temperature region of the
MWI for a time period that exceeds the time required for it to
completely combust. Because the combustion reaction rate
• increases with increasing temperature, a shorter residence time
is required for combustion at higher temperatures (assuming the
presence of good combustion conditions). Adequate oxygen
supplies and turbulence sufficient to promote the mixing of
organic materials and oxygen are also essential for efficient
combustion. Inadequate mixing of combustible gases and air can
result in emissions of incomplete combustion products.
Turbulence within the primary chamber helps to break down the ash
layer formed around burning particles of waste and expose the
waste material to the high temperatures and combustion air. Bed
turbulence is needed to maintain the combustion process and the
elevated temperatures throughout the bed.
Throughout this report, unless otherwise indicated,
discussions focus on dual- chambered MWI's because of their
prevalence in the industry. In these units, sequential
combustion operations are carried out in two separate chambers.
The primary chamber accepts the waste, and the combustion process
is begun. Three processes occur in the primary chamber. First,
the moisture in the waste is evaporated. Second, the volatile
fraction of the waste is volatilized, and the volatilized gases
are directed to the secondary chamber. Third, the nonvolatile
combustible portion (fixed carbon) of the waste is burned. The
typical operating temperature range for primary chambers is 650°
to 760°C (1200° to 1400°F), but the temperatures can range from
400° to 980°C (750° to 1800°F).3"5 Combustion gases containing
the volatile combustible materials from the primary chamber are
directed to the secondary chamber. Here the gases are burned
with excess air, and at least one auxiliary fuel burner is used,
" as necessary, to maintain temperatures. According to most
•& manufacturers, typical operating temperatures for secondary
chambers range from 870° to 1100°C (1600° to 2000°F). The
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combustion gases from the secondary chamber are then vented
through the stack to the atmosphere.
Medical waste incinerators have the potential to emit a
variety of air pollutants. The pollutants from MWI's either
exist in the waste feed material and are released unchanged
during combustion, or they are generated as a result of the
combustion process itself. These pollutants include particulate
matter (PM) ; toxic metals; toxic organics; carbon monoxide (CO);
and the acid gases hydrogen chloride (HC1), sulfur dioxide (S02)/
and nitrogen oxides (NOX). In addition to emissions of
pollutants through the combustion air stack, there is the
potential for fugitive emissions in the medical waste
incineration process. These emissions occur while charging the
waste, handling the ash, and handling and transporting the catch
or residue from air pollution control devices (e.g., fabric
filters).
3.0 MEDICAL WASTE CHARACTERISTICS, SEGREGATION, STORAGE, AND
TRANSPORTATION
The characteristics of medical waste, in terms of its
physical and chemical properties, are described in Section 3.1.
Section 3.2 describes current medical waste segregation and
storage practices. Transportation practices are discussed in
Section 3.3.
3.1 CHARACTERISTICS OF MEDICAL WASTE COMPONENTS
Medical waste is characteristically heterogeneous,
consisting of items composed of many different materials. The
composition of the wastes depends on the type of generator and
the source of the waste within the generator facility.
Activities and procedures within the facility can vary
significantly from day to day, making it difficult to predict the
composition of the waste. Therefore, no data are available from
which a representative characterization of medical waste can be
formulated, and only the components of the waste can be
characterized. The chemical and physical properties of the
components of wastes treated in MWI's vary considerably--not only
from charge to charge, but within each charge to the incinerator.
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The waste characteristics are important because they may affect
combustion efficiency and emission characteristics. A study of
hospitals in Ontario provided information on the heating value,
bulk density, and moisture content of different medical waste
materials. The results from this study are presented in
Tables 2a (metric units) and 2b (English units).3 As shown in
these tables, the heating values (as fired) range from about
2,330 kilojoules per gram (kJ/g) (1,000 British thermal units per
pound [Btu/lb]) for high-moisture, low-heat-content anatomical
waste to 46,500 kJ/g (20,000 Btu/lb) for low-moisture, high-heat-
content plastics such as polyethylene. Bulk densities ranged
from 80 kilograms per cubic meter (kg/m3) (5 pounds per cubic
foot [lb/ft3]) to 8,000 kg/m3 (500 lb/ft3). Moisture contents
varied from zero to 100 percent.
The chemical composition of the medical wastes, particularly
the metals and plastics, are also of concern because of their
impact on air pollutant emissions. Metals and metal compounds
that vaporize at the hearth temperatures encountered in the
primary combustion chamber may be emitted as metal oxides.
Halogenated plastics such as polyvinyl chloride (PVC) produce
acid gases (e.g., HC1). The presence of the chlorinated wastes
may also contribute to the formation of toxic organic pollutants
such as dioxins (CDD's) and furans (CDF's).
3.2 MEDICAL WASTE SEGREGATION AND STORAGE PRACTICES
The degree to which medical waste is segregated is typically
a function of the size of the generator and the economics of
disposal options. If a large incinerator is available or if
unsegregated wastes may be hauled to a local landfill, a
generator may combine most or all medical wastes in preparation
for disposal. However, a generator might tend to segregate
medical waste more carefully in cases where only a small
incinerator is available or when the waste hauling charges are
significant, and the added costs of special handling would apply
to the noninfectious component of medical waste as well.
During the segregation process, efforts are generally made
to exclude from the medical wastes certain materials that may
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TABLE 2a. "PHYSICAL CHARACTERISTICS OF MEDICAL WASTE COMPONENTS'
(Metric Units)
Component description
Human anatomical
Plastics
Swabs, absorbants
Alcohol, disinfectants
Animal-infected anatomical
Glass
Beddings, shavings, paper, fecal
matter
Gauze, pads, swabs, garments,
paper, cellulose
Plastics, PVC, syringes
Sharps, needles
Fluids, residuals
HHV dry basis,
kJ/g
18,600-27,900
32,500-46,500
18,600-27,900
25,500-32,500
20,900-37,100
0
18,600-20,900
18,600-27,900
22,500-46,500
140
0-23,200
Bulk density as
fired, kg/m3
800-1,200
80-2,300
80-1,000
800-1,000
500-1,300
2,800-3,600
320-730
80-1,000
80-2,300
7,200-8,000
990-1,010
Moisture
content of
component,
weight %
70-90
0-1
0-30
0-0.2
60-90
0
10-50
0-30
0-1
0-1
80-100
Heat value as
fired, kJ/g
1,860-8,370
32,300-46,500
13,000-27,900
25,500-32,500
2,090-14,900
0
9,300-18,800
13,000-27,900
22,300-46,500
140
0-4,640
TABLE 2b. PHYSICAL CHARACTERISTICS OF MEDICAL WASTE COMPONENTS-
(English Units)
Component description
Human anatomical
Plastics
Swabs, absorbants
Alcohol, disinfectants
Animal-infected anatomical
Glass
Beddings, shavings, paper, fecal
matter
Gauze, pads, swabs, garments,
paper, cellulose
Plastics, PVC, syringes
Sharps, needles
Fluids, residuals
HHV dry basis,
Btu/lb
8,000-12,000
14,000-20,000
8,000-12,000
11,000-14,000
9,000-16,000
0
8,000-9,000
8,000-12,000
9,700-20,000
60
0-10,000
Bulk density as
fired, Ib/fi3
50-75
5-144
5-62
48-62
30-80
175-225
20-45
5-62
5-144
450-500
62-63
Moisture
content of
component,
weight %
70-90
0-1
0-30
0-0.2
60-90
0
10-50
0-30
0-1
0-1
80-100
Heat value as
fired, Btu/lb
800-3,600
13,900-20,000
5,600-12,000
11,000-14,000
900-6,400
0
4,000-8,100
5,600-12,000
9,600-20,000
60
0-2,000
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create special problems in the combustion process, adversely
impact the composition of the effluents or residues from the
process, or unnecessarily contribute to the volume of wastes to
be incinerated. For example, the presence of batteries or
radiological materials in the waste feed may account for high
concentrations of heavy metals (e.g., lead, mercury, and cadmium)
in incinerator ash, and so these items are often segregated from
the wastes to be combusted. While paper plates, polystyrene
cups, and other "dry" hospital cafeteria wastes may be included
with medical wastes, cafeteria food wastes are often excluded
from the medical wastes to be incinerated because of their high
moisture content. Metal cans from cafeterias also are generally
excluded. Large stacks of computer paper are usually segregated
from medical wastes unless they are shredded prior to
incineration. Bulky cardboard is often compacted and recycled
rather than incinerated.
In addition to the above examples of waste segregation,
other wastes are appropriately excluded from medical waste
intended for incineration. While the Nuclear Regulatory
Commission (NRC) permits the incineration of certain wastes
containing low-level radioactive materials (e.g., scintillation
vials, research animal carcasses, and certain chemotherapy wastes
with radioactive concentrations below a specified level), special
/permits are required to treat other radioactive wastes. In most
cases, it is inappropriate to use MWI's to dispose of some
radioactive wastes and certain hazardous wastes regulated under
RCRA. However, there are a few incineration facilities designed
primarily as MWI's that have obtained permits to treat wastes
regulated under RCRA.
Color-coded bags (usually polyethylene) and containers are
frequently used to help segregate and identify medical waste.
Most often, red or red-orange bags are used for infectious
wastes, and these wastes are usually double-bagged. For
aesthetic reasons, opaque bags are generally used for certain
'.• types of wastes (e.g., pathological). Other colored containers
may be used based on the protocol of the particular generator.
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For example', generators might use blue bags for body fluid
wastes, orange bags for chemotherapy wastes, and brown bags for
general waste. Plastic bags containing medical wastes are
sometimes placed in plastic-lined, corrugated cartons or fiber
drums, which are then appropriately labelled. Sharps, such as
needles, scalpels, and pipettes, are commonly placed in rigid,
colored, puncture-proof plastic containers. Capped or tightly
stoppered bottles or flasks may be used for liquid wastes, as may
tanks. Use of the biological hazard symbol on appropriate
packaging is recommended. Regardless of the type of containers
used, the integrity of the packaging must be preserved throughout
handling, storage, and transportation.
The storage of medical wastes prior to onsite treatment or
offsite disposal is typically kept to a minimum. Some States
regulate storage times. For example, Massachusetts allows
infectious waste to be stored for 24 hours at room temperature
(18° to 25°C [64° to 77°F]) or for 72 hours at refrigerated
temperatures (1° to 7°C [34° to 45°F]).1 Wastes stored without
refrigeration for several days are prone to increased rates of
microbial growth and putrefaction. Ideally, wastes are stored in
areas with refrigeration and provisions for regular disinfection
to avoid the spread of disease by rodents and vermin. Storage
areas typically are secured from public access. These areas
generally display the biological hazard symbol.
3.3 MEDICAL WASTE TRANSPORTATION
3.3.1 Transportation Within the Facility
Medical wastes are transported within the generating
facility using chutes and wheeled containers. (Chutes are not
recommended for transporting infectious wastes.) Plastic bags
and other containers described in the previous section may be
placed in rigid, leakproof containers with wheels to be
transported to 'storage or treatment areas. When mechanical
loading devices are used, care must be taken to avoid rupturing
the packaged wastes.
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3.3.2 Transportation of Untreated Medical Waste to Offsite
Locations
Medical waste intended for offsite treatment generally is
transported in closed and leakproof dumpsters or trucks to
prevent the waste from scattering, spilling, and leaking during
transport. Because the truck is not considered to be a rigid
containment system, medical wastes typically are placed in rigid
or semi-rigid, leakproof containers before being loaded into a
truck. . .
When medical waste is transported offsite, specific
packaging requirements are generally imposed by State or Federal
regulations. These regulations typically require that infectious
waste be placed in double (plastic) bags, with each bag tied or
taped and the bags placed in plastic-lined, rigid, corrugated
cartons or fiber drums, which are then sealed or taped. The
containers are generally required to be marked with the universal
biohazard symbol or the words "infectious waste," and if
chemotherapy wastes are included, the containers must be so
marked. Other labeling of the containers, as well as manifesting
procedures, must conform with the statutory requirements of the
generator's State. Classifications of medical, and specifically
infectious, wastes vary among the States. Drivers or
warehousemen at the disposal site may inspect each shipment of
medical waste (e.g., for structural integrity of the containers
or for the presence of radiation hazards). The disposal company
may reserve the right to refuse any "off-spec" packages.
Carts and other reusable transport mechanisms should be
disinfected frequently and, when used to transport infectious
wastes, should not be used to transport other materials prior to
decontamination.
Should storage of medical waste during transport or at the
offsite facility be required, procedures are the same as those
discussed in Section 3.2.
As discussed in Section 3.2, the degree of segregation of
medical wastes (i.e., infectious vs. noninfectious or regulated
vs. nonregulated) is likely to be greater when the waste is to be
11
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shipped offsite for treatment. Therefore, the characteristics of
the waste may be considerably different from those of medical
waste treated onsite. Because of the requirements of the
disposal facility and the special handling costs and regulatory
requirements associated with hauling medical wastes, waste
shipped offsite is more likely to be composed primarily of
materials defined as infectious.
4.0 MEDICAL WASTE INCINERATION PROCESSES AND PROCESS COMPONENTS
The medical waste incineration process can be described in
terms of the following steps: waste charging, primary chamber
combustion, solids movement though the primary chamber, secondary
chamber combustion, combustion gas handling, and ash removal.
Figure 1 is a process flow diagram that illustrates how these
steps relate to each other in the incineration system.
The important factors that help to characterize an MWI
system and its operation are the mode of operation, the method of
waste feed charging, the method of ash removal, and the air
distribution to the combustion chambers. The basic types of
MWI's can be classified by mode of operation as continuous-duty,
intermittent-duty, and batch-duty systems. All MWI's, regardless
of the type of waste burned, fit into one of these MWI types.
However, MWI's burning pathological waste, while they fall under
the intermittent-duty category, operate significantly differently
and have significantly different emission characteristics from
other intermittent-duty MWI's. Therefore, pathological MWI's are
treated as a separate subcategory of MWI's. In each of these
systems, sequential combustion operations typically are carried
out in two separate chambers (primary and secondary). Table 3
characterizes the major types of MWI's with respect to these
factors.
Waste charging to the primary chamber is accomplished either
manually or mechanically. Typically, manual waste feed charging
is used on batch-duty units and those intermittent-duty MWI's
with capacities less than 180 kilograms per hour (kg/hr)
(400 pounds per hour [Ib/hr]). Intermittent-duty units larger
than 180 kg/hr (400 Ib/hr) and continuous-duty MWI's generally
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have a mechanical waste feed charging system. Continuous-duty
units have a means of moving the waste/ash bed from the charging
end to the ash-discharge end/while intermittent- and batch-duty
units utilizing manual charging have no means of solids transfer
in the primary chamber.
Ash is removed either periodically or continuously,
depending upon the operating mode of the MWI (see Table 3).
Continuous ash removal, used for continuous-duty MWI's, takes
place while the incinerator is operating. Periodic ash removal
is performed either manually or mechanically (typically on the
morning after a burn) in units without continuous ash removal
systems.
The stoichiometric amount of combustion air is the quantity
of air needed to provide exactly the theoretical amount of oxygen
needed for the carbon and hydrogen in the waste to completely
combust. For MWI's, air distribution can be classified based on
whether the primary chamber operates under starved
(substoichiometric) or excess-air (an amount above
stoichiometric) conditions. In most MWI's, the combustion
process in the primary chamber proceeds in a substoichiometric
oxygen atmosphere. However, pathological systems operate with
excess air in the primary chamber.
With the exception of pathological MWI's, the continuous-
duty, intermittent-duty, and batch-duty MWI's are designed to
burn general medical waste (including pathological waste) that
typically has a heating value of 1.98 x 107 Joule/kg
(8,500 Btu/lb). Pathological MWI's are designed to burn only
pathological waste, typically having a heating value of 2.3 x
106 Joule/kg (1,000 Btu/lb). However, there is a pathological
"dual mode" system that operates under substoichiometric
conditions when burning nonpathological wastes and under excess-
air conditions when treating only pathological wastes.
The design capacities of MWI's are presented in Table 4.
These capacities range from 20 kg/hr (50 Ib/hr) for intermittent-
duty, pathological and nonpathological systems to 2,830 kg/hr
(6,250 Ib/hr) for continuous-duty systems. For batch units, the
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capacities range from 70 kg/batch (150 Ib/batch) to
1,720 kg/batch (3,800 Ib/batch),
Each of the basic types of MWI's, along with the variations
in their process components, are discussed in greater detail in
the following sections. Sections .4.1, 4.2, and 4.3 describe
continuous-duty, intermittent-duty, and batch-duty MWI's,
respectively, with respect to the combustion of general medical
waste. Section 4.4 describes pathological MWI's (also
intermittent-duty MWI's) with respect to the combustion of
pathological waste and also includes a description of retort
hearth MWI's. Section 4.5 describes the variations in process
components among the basic MWI types.
4.1 COISTTINUOUS-DUTY SYSTEMS
This section first provides a brief overview of the general
medical waste combustion process occurring in the MWI, describes
the flow of combustion air and exhaust gases through the system,
and discusses the control of combustion air to the primary and
secondary chambers. Secondly, this section describes the unique
features of continuous-duty systems.
Figure 2 is a schematic of an MWI. The waste enters the
primary chamber, where it is ignited. The moisture in the waste
is evaporated, the volatile fraction is vaporized, and the fixed
carbon remaining in the waste is combusted. The combustion air
flow to the primary chamber may be set at a fixed rate or it may
be varied based on primary chamber exit gas temperature to
maintain a substoichiometric oxygen condition. The gases
containing the volatile combustible materials from the primary
chamber are directed to the secondary chamber. In the secondary
chamber, the combustion air is regulated to provide an excess-air
combustion condition and is introduced to the chamber in a manner
that produces turbulence and promotes mixing of the combustion
gases and combustion air. Combustion air is regulated using
modulating combustion air dampers or fans that are activated
based on the secondary chamber exit gas temperatures. Burning
the combustion gases under conditions of high temperature, excess
oxygen, and turbulence promotes complete combustion.
17
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Limiting air to substoichiometric conditions in the primary
chamber prevents rapid combustion and favors the quiescent
conditions that minimize entrainment of PM in the combustion
gases. Also, control of the distribution and amount of
combustion air allows the primary chamber temperatures to be
maintained below the melting and fusion points of most metals,
glass, and other noncombustibles, thereby minimizing slagging and
clinker formation. On the other hand, sufficiently high
temperatures can be maintained in a turbulent condition with
excess oxygen in the secondary chamber to ensure complete
combustion of the combustion gases, while at the same time
avoiding temperatures that are hot enough to cause refractory
damage.
The continuous-duty MWI has an operating- cycle that can
accommodate waste charging for an unrestricted length of time
because ash is automatically discharged from the incinerator on a
continuous basis. The unit can be automatically charged with
relatively small charges at frequent, regulated time intervals.
Available information indicates that nearly all- of these units
are used by commercial facilities, hospitals, and
laboratories. "^ These end-users tend to be facilities whose
medical waste incineration requirements are continuous and do not
allow for periodic shutdown of the units for ash removal.
The primary chamber of continuous-duty MWI's may comprise
either a fixed-hearth, a rotary kiln, or a moving hearth such as
a Pulse Hearth™ or a stoker. Currently, fixed-hearth systems are
significantly more prevalent than the other types. Because of
their size and because of the need to move waste through the
system effectively, most continuous-duty, fixed-hearth MWI's
utilize stepped hearths. Figure 3 depicts a continuous-duty,
stepped-hearth MWI with internal ash transfer rams..
Figure 4 is a simplified schematic of a rotary kiln. The
primary chamber is a rotating cylindrical chamber that is
slightly inclined from the horizontal plane. Waste is fed at the
higher end of the rotating chamber. For wastes other than
medical wastes, combustion air provided to the primary chamber
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typically creates an excess-air atmosphere. However, a major
manufacturer of rotary kilns used as MWI's reports that the
airflow to the primary chamber in these kilns is
substoichiometric.22 Operating the kiln under these conditions
reduces kiln size and decreases auxiliary fuel usage in the
secondary chamber. Inside the rotating chamber, moisture and
volatiles are vaporized from the waste, and the waste is ignited.
As the chamber rotates, the solids tumble within the chamber and
slowly move down the incline toward the discharge end. The
turbulence of the waste provides exposure of the solids to the
combustion air. Combustion of the solids occurs within the
rotating chamber, and the residue ash is discharged from the end
of the kiln into an ash removal system. The volatile gases pass
from the primary chamber into the secondary chamber, where
combustion of the gases is completed.
Because the waste continuously moves down the length of the
rotating chamber and ash is removed continuously, the
incineration system is designed to operate with continuous waste
feed input. Available information indicates that relatively few
rotary kilns are being used as MWI's, and most of these are used
at hospitals.10' 16-19
Pulse Hearth™ and stoker systems are used to a lesser extent
than fixed-hearth and rotary kiln MWI's and are described in
Section 4.5.2.2.
4.2 INTERMITTENT-DUTY SYSTEMS
An intermittent-duty MWI typically has an operating cycle of
less than 24 hours. The unit is designed to accept waste charges
for durations of 8 to 16 hours, depending upon its size. Once
ash builds up to a level that interferes with normal charging of
the unit, the unit must be shut down and the ash removed. The
intermittent charging procedure allows the daily charge to the
MWI to be divided into a number of smaller charges that can be
introduced over the combustion cycle. Waste is generally charged
every 6 to 15 minutes. The following is a typical daily
operating cycle for an intermittent-duty MWI.
22
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1. Cleanout of ash from previous day 15 to 30 minutes
2. Preheat of incinerator 30 to 60 minutes
3. Charging of waste Varies (up to
16 hours)
4. Burndown 2 to 4 hours
5. Cooldown 5 to 8 hours
The burndown step indicates the period of time in the cycle
during which no additional waste is charged to the incinerator,
and the solid phase combustion of the waste bed is taking place
in the primary chamber. The cooldown step, the period during
which the MWI is allowed to cool, occurs at the end of the
operating cycle, after the burndown step and may or may not use
forced air.
A schematic of an intermittent-duty MWI is presented in
Figure 5. This unit has a vertically oriente.d primary chamber
followed by a horizontal secondary chamber. Intermittent-duty
MWI's are used in hospitals, laboratories and research
facilities, nursing homes, and veterinaries.6"10'16'20'21
4.3 BATCH-DUTY SYSTEMS
In this type of system, the incinerator is charged with a
single "batch" of waste, the waste is combusted, the incinerator
is cooled, and the ash residue is removed; the cycle is then
repeated. When the unit is loaded, the incinerator is sealed,
and the incineration cycle then continues through burndown,
cooldown, and ash removal without any additional charging.
Depending on the size of the batch MWI, batch units may operate
on a 1- or 2-day cycle. Ash is removed either one day or two
days after the initial batch charge of waste. In these units,
the primary and secondary chambers are often vertically oriented
and combined within a single casing. Figure 6 is a schematic of
a batch-duty MWI. This unit's combustion chambers are
rectangular in design and are contained within the same casing.
According to information obtained on batch-duty MWI's, nearly all
these units are used at hospitals.11
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4.4 PATHOLOGICAL SYSTEMS
Incinerators that burn .only pathological wastes operate
under excess-air conditions. Excess-air systems are better
suited to the incineration of pathological wastes than red bag
wastes because the volatile content of pathological waste is low,
and, in general, the waste composition is not highly variable.
The primary burner provides most of the heat input, and the
incinerator operates in a steady, constant mode with a regular,
consistent combustion air input and excess-air level.
There is a "dual mode" system that is designed to burn
either pathological or nonpathological (general medical) wastes.
The dual mode feature is achieved through the use of a switch
that controls the operation of the primary chamber burners and
the combustion air blowers. In the pathological mode, the
primary chamber burner(s) cycle(s) on and off more frequently (or
remains on) to accommodate the combustion requirements of the
pathological wastes with their lower Btu values. Because of the
high moisture content of the pathological wastes, combustion
cannot be sustained without using auxiliary fuel. The air supply
required to operate the burner and the relatively small amount of
combustible gases generated from the waste result in an excess-
air condition in the primary chamber. When the unit is operated
in the nonpathological mode, the primary burner is turned off
because the waste provides its own fuel. In this mode the
underfire combustion air levels are set to maintain a
substoichiometric condition in the primary chamber.23
Pathological MWI's are typically designed for intermittent-
duty operation--i.e., these units generally do not have
automatic, continuous ash removal systems. Consequently, the
incinerator must be shut down at routine intervals (e.g., daily)
for ash removal. Pathological systems are used at hospitals,
nursing homes, research laboratories, and veterinaries.16'20'21
A traditional design that has been used to burn medical
waste in the past is the retort hearth system. This system is
being used to a limited extent only and can be characterized as
26
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an older, existing hospital incinerator. The principal design
configuration for the unit is shown in Figure 7.
The system operates under excess-air conditions in the
primary and secondary chambers. Combustion of the waste begins
in the primary chamber. The waste is dried, ignited, and
combusted by heat provided by a primary chamber burner, as well
as by hot chamber walls and hearth that are heated by the flue
gases. The combustion gases containing the volatiles pass out of
the primary chamber through a flame port into a mixing chamber
and then pass into the secondary chamber. Secondary air is added
through the flame port and mixed with the combustion gas in the
mixing chamber. A secondary burner is provided in the mixing
chamber to maintain' adequate temperatures for complete combustion
as the gases pass into and through the secondary combustion
chamber. Waste is fed manually or mechanically with single or
multiple batches per burn. Ash is removed on a batch basis at
the end of the burn. The retort design accommodates capacities
under 230 kg/hr (500 Ib/hr),24
The retort hearth system is best suited to burn pathological
wastes. There are drawbacks to using these units to incinerate
general medical wastes. Retort units employ overfire combustion
,air predominantly to promote surface combustion. This excess,
overfire air in the primary chamber results in entrainment of fly
ash, which can cause excessive PM emissions. Also, because the
primary chamber is in an excess-air mode and these older units
lack controls, the combustion air levels and the combustion'rate
within the primary chamber are not easily controlled.
Consequently, there may be no assurance of complete combustion
when waste composition and volatile content of the waste
fluctuate over a wide range. Because true pathological waste
does not exhibit the variation in composition found in other
medical wastes, and it has a lower volatile content, these units
are better suited to incinerate pathological wastes than general
hospital wastes.
27
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Charging
Door
Slack
Ignition Chamber
Haarth
Secondary
Air Ports
Secondary
Burner Port
Mixing
Chamber
First
Underhearth
Port
Secondary
Combustion
Chamber
Mixing Chamber
Rame Port
Charging
Door
Hearth
Primary
Burner Port
Second
Underhearth
Port
Figure 7. Retort hearth incinerator.
28
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4.5 VARIATIONS IN MWI PROCESS COMPONENTS
Several process components are integral parts of each of the
medical waste incineration processes. These include waste feed
mechanisms, primary and secondary chamber configurations, solids
transfer mechanisms, air supply and handling systems, auxiliary
burners, ash removal and handling processes, energy recovery
options, and stack bypass systems. The variations in these
components among the basic MWI processes are described in this
section.
4.5.1 Waste Loading and Feeding Mechanisms
Two basic types of systems are used to charge waste into
MWI's: manual and mechanical. Manual charging involves feeding
the waste directly into the primary chamber without any
mechanical assistance. This charging system is generally used
for batch-fed and small, intermittent-duty MWI's, including
pathological systems.
Automatic, or mechanical, equipment for charging the waste
is used for all continuous-duty models, including rotary kilns,
and for most intermittent-duty MWI's with capacities larger than
about 90 to 140 kg/hr (200 to 300 Ib/hr), including pathological
systems. One mechanical system for charging wastes into the MWI
is the hopper/ram. Some pathological MWI's are fed through top-
loading mechanisms. Veterinary facilities, for instance,
sometimes use this method of waste feeding when very large animal
carcasses are involved.
Figure 8 is a schematic of a commonly used hopper/ram
assembly. In this system, waste is manually placed into a
charging hopper, and the hopper cover is closed. A fire door
isolating the hopper from the incinerator opens, and the ram
moves forward to push the waste into the incinerator. The ram
then reverses to a location behind the fire door. After the fire
door closes, the ram retracts to the starting position and is
ready to accept another charge. A water spray is typically
provided to quench the ram face as it retracts. The entire
charging sequence is usually timed and automatically controlled.
The cycle can be started manually by the operator, or, in some
29
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Hydraulic Fire
Door Actuator
Hopper Cover
Hydraulic
Ram
Actuator
Charging ~£am f**
Ram ?uench
Spray
Wasta
Charging
Hopper
Primary
Combustion
Chamber
Fire Door
Enclosure
Incinerator
Opening
Figure 8. Hopper/ram mechanical waste feed system.
25
30
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systems, the cycle starts automatically on a predetermined basis.
The charging frequency can be changed by adjusting the length of
time between charges in the automatic sequence. The size of the
hopper limits the volume of waste that can be fed in each charge;
therefore, the size of the charge may be decreased by not filling
the hopper to capacity.
In some facilities, mechanical loading equipment is used to
deposit the waste material into the waste feeding systems. Waste
containers may be lifted and dumped into the MWI charging hopper
with no handling of the waste by the MWI operator. In fully
automated, computer-controlled systems, the waste container is
conveyed to a weighing platform. After the weight of the waste
is recorded, the container is automatically emptied into the feed
chute. Controlled amounts of wastes are conveyed from the end of
the feed chute to the ram hopper. The door isolating the hopper
from the primary chamber is automatically opened at preset
intervals, and the wastes are fed into the chamber. During the
early stages of the automatic cycle, prior to charging, the
wastes may be subjected to screening sensors to check for
radioactivity levels in the waste.
4.5.2 Primary Chamber Variations
4.5.2.1 Primary Chamber Configuration. The sizes and
shapes of the primary chambers for each of the basic MWI systems
vary. The primary chamber of the continuous-duty, rotary kiln is
cylindrical in shape and is slightly inclined from the horizontal
plane. The primary chamber on other MWI's may be cylindrical,
square, or rectangular in shape and may be vertically or
horizontally oriented. In all units, the chamber size is
designed for a specified volume of waste with a particular Btu
content. In intermittent-duty systems, the size of the primary
chamber determines the total amount of waste that can be loaded
and the amount of ash that can be accumulated without restricting
the overall process. For continuous-duty units, the size of the
primary chamber will impact the rate of charging and the quality
of burnout. Some continuous-duty systems are designed with
31
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larger primary chambers to accommodate longer solids retention
times and more complete combustion of the fixed carbon.
4.5.2.2 Solids Transfer Systems in the Primary Chamber.
Small MWI's utilizing manual charging and some small MWI's with
mechanical charging systems have no means of solids transfer, or
agitation. Waste is charged into the unit until the ash builds
up to the point where no more waste can safely be charged. Many
MWI's with a single hearth and a waste feed charge ram use the
ram to move burning waste and ash across the hearth. As a new
load is pushed into the primary chamber, the previous load is
pushed forward. Each subsequent load has the same effect of
moving the waste across the hearth. Some single-hearth systems
also may have an ash ram located below the charge ram at the
hearth level. This ram is used both to stoke the burning waste
(i.e., agitate the waste bed to expose all surfaces to heat and
air) and to move the waste and ash toward the discharge end of
the chamber. Stoking may be automatic or manual. Figure 9 is a
schematic of a single-hearth, intermittent-duty MWI equipped with
an ash ram.
Large, continuous-duty MWI's often have multiple hearths
arranged in a stepped fashion. This type of system is shown in
Figure 3. The face of each step is that of an internal ash
transfer ram. These internal rams are automatically controlled
to operate in sequence to clear off space on each step for the
ash pushed off from the previous (higher) step. The ash
discharge ram operates first by pushing ash into the ash pit (dry
or containing water as a quench). Then the ash transfer ram for
the step behind the ash discharge ram pushes ash from its step
onto the ash discharge step. The process of clearing space is
repeated back to the waste feed ram, which pushes waste onto the
top step, thereby pushing the previous charges onto the space
cleared by the-'ash transfer ram for the next step. This system
causes agitation of the waste, as the ash is moved from hearth to
hearth, thereby improving solid-phase combustion.
At least one manufacturer provides a stoker to move waste
through the primary chamber.26 The stoker consists of a double
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reciprocating grate that mixes the waste and constantly exposes
it to heat and oxygen. The stoker comprises a series of
overlapping, alternating stationary and movable grates. While a
movable grate positioned over a stationary grate is advancing, a
movable grate positioned under that stationary grate retracts to
form a step 15 inches high. This action causes waste to fall and
mix as it moves across the length of the stoker.
One manufacturer offers a Pulse Hearth™ in the primary
chamber.^ The entire floor of the chamber consists of the pulse
hearth, a refractory-lined, stepped hearth suspended on the
outside of the primary chamber at four points by steel cables.
The hearth is pulsed forward and upward by an external, pneumatic
system. This pulsing action moves the waste forward from the
charge end of the primary chamber to the ash removal end.
Rotary kilns mix and transfer solids through the rotation of
the cylindrical primary chamber, which is slightly inclined from
the horizontal plane. The solids are tumbled within the kiln and
slowly move down the incline toward the discharge end of the
chamber.
4.5.2.3 Auxiliary Burners. In the primary chamber, with
the exception of pathological MWI's, auxiliary burners are used
only to ignite the waste. Once the waste has started to burn,
the primary chamber auxiliary burners are rarely, if ever, needed
again. Typically, the setpoint for these burners is about 430°C
(800°F), so that if the chamber temperature falls below the
setpoint, the burner comes on. The temperatures in the primary
chamber are typically above 538°C (1000°F), assuming the MWI is
being properly charged with waste. In pathological MWI's, the
auxiliary burner usually stays on because the heating value of
the pathological waste (2,330 kJ/g [l,pOO Btu/lb]) is not high
enough to sustain combustion and, therefore, requires additional
heat from the burner for combustion.
4.5.2.4 Air Supply and Handling. Air is supplied to the
primary chambers of MWI's primarily as underfire air through air
ports by a single forced-draft blower. The air supply can be
reduced or increased by adjusting control dampers or by adjusting
34
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the speed of the fan. In fixed-hearth systems, the air ports
typically consist of small holes, arranged at regular intervals,
built into the floor of the hearth. If the hearth is rectangular
or square, the ports typically will be arranged in a regular grid
equally spaced or in a series of rows across the hearth. If the
hearth is circular, the ports may be arranged in concentric
circles or, if the unit is very small, in one circle.
Several methods are currently in use on MWI's to control the
amount of combustion air to the primary chamber so as to maintain
substoichiometric oxygen levels. Because of the relationship
between the stoichiometry of the combustion air and temperature,
temperature can be used as an indicator of combustion air levels
in the chamber. Maximum combustion temperatures are attained at
stoichiometric conditions. As the amount of excess air increases
above the stoichiometric point, the combustion temperature
decreases because of the energy needed to heat the combustion
air. However, while in the substoichiometric region, increasing
the amount of air towards the stoichiometric point increases
temperature as more oxygen becomes available for combustion. A
graphical representation of the relationship between combustion
temperature and combustion air levels is presented in Figure 10.
In many systems, the primary chamber air systems are
automatically,- continuously controlled by regulating (or
"modulating") the amount of air supplied in order to maintain the
desired combustion chamber temperatures, regardless of the
variations in waste characteristics (e.g., moisture content,
heating value). One or more thermocouples measure the
temperature in the primary chamber. If the temperature is above
the setpoint, the control feedback loop automatically adjusts
(closes) the damper, limiting the air supply into the chamber,
thereby reducing the rate of combustion and the thermal heat
output. Conversely, if the temperature is below the setpoint,
the damper is automatically adjusted (opened) to allow more air
in to increase the temperature. In other systems, particularly
batch or intermittent-duty systems, the combustion air level
control is simplified and may consist of the automatic switching
35
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TEMPERATURE
MAXIMUM
TEMPERATURE
SUBSTOICHIOMETRIC AIR | EXCESS AIR
PERCENT EXCESS AIR
Figure 10.
Relationship between temperature and combustion
air levels.
36
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of the combustion air rate from a high to a low setting
(adjusting damper position or blower speed) when temperature
setpoints are reached or at preset time intervals.
In rotary kilns, forced draft is used to introduce
combustion air into the kiln through the fixed endplate. Because
of the physical orientation of the kiln, the air enters the
chamber as overfire air. The air supply is controlled in the
same manner as in the intermittent- or continuous-duty systems
described above.
Pathological MWI's are designed for surface combustion of
the waste, which is achieved predominantly by using a burner and
limiting the amount of "underfire air" in the primary chamber.
In some systems, combustion air ports may be built into the side
walls of the chamber. While in all pathological units combustion
air comes in through the burner flame port(s), in some units
additional excess air ("underfire air") may be introduced through
the side wall ports. When burning pathological waste, both air
and direct heat are required--first to vaporize the moisture in
the layer of tissue and, subsequently, to burn the dried layer.
This combustion occurs layer by layer, and, because of its low
heating value (2,330 kJ/g [1,000 Btu/lb]), pathological waste
requires direct contact by the flame of the primary chamber
auxiliary fuel burners.
4.5.2.5 • Other Features. In some MWI systems, the primary
chamber is equipped with a thermocouple to govern the activation
of a water spray when the chamber temperature exceeds a preset
value. Some systems use steam injection through underfire air
ports to keep the temperature of the ash bed down and to
facilitate burnout of fixed carbon in the ash bed. Because steam
injection helps to maintain ash bed temperatures below the
melting and fusion points of most combustibles, this procedure
also helps to prevent clinker buildup and slagging that could
plug the underfire air ports.28
37
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4.5.3 Secondary Chamber Variations
4.5.3.1 Secondary Chamber Configuration. There are several
variations in the configuration of secondary chambers. As with
primary chambers, secondary chambers may be cylindrical, square,
or rectangular, and they may be vertically or horizontally
oriented. Although the secondary chamber of the rotary kiln is
sometimes oriented horizontally, it is often vertically oriented
to reduce carryover of entrained particulates. The chamber is
usually cylindrical, but it can also have a box-like shape.
All secondary chambers must have adequate volume to accept
and completely oxidize all the volatile gases generated in the
primary chamber and to maintain sufficient combustion air so that
excess oxygen is available.
The volume of the secondary chamber is the key parameter
influencing the residence time of the combustion gases. If the
incinerator is designed for a specified residence time and
volumetric flow rate, the secondary chamber is sized accordingly.
Some MWI's have a tertiary chamber that serves to increase the
residence time of the combustion gases at high temperatures.
Thus, the tertiary chamber can be regarded as an extended
secondary chamber.
4.5.3.2 Auxiliary Burners. The auxiliary fuel burner(s)
are designed to maintain setpoint temperatures, and they operate
in conjunction with modulating air controls to maintain these
temperatures in the secondary chamber. The burners either
modulate on and off or are equipped with high and low settings.
In some units, fully modulating burners are used.
4.5.3.3 Air Supply and Handling. All secondary chambers
operate in an excess-air mode. The excess air typically is
introduced into the secondary chamber through a flame port at
right angles (or tangentially) to the incoming combustion gases
from the primary chamber, thereby creating a turbulent zone that
promotes mixing of the air and combustion gases. In some
applications, combustion air is supplied to the secondary chamber
in multiple locations.
38
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Typically, air is supplied to the secondary chamber through
a port by a forced-draft blower. This air supply is controlled
as described for primary chambers in Section 4.5.2.4. Some
systems, particularly batch- or intermittent-duty units, simply
control the combustion air level with automatic switching of the
combustion air rate from high to low to rectify deviations from
the setpoints.
As discussed in Section 4.5.2.4, the relationship between
combustion air stoichiometry and temperature is such that
temperature can be used as a control to maintain the appropriate
combustion air level. A control feedback loop, based on
temperature measured by the secondary chamber thermocouple(s),
can be used. This system operates in a manner similar to that
described for the primary chamber air supply (see
Section 4.5.2.4). However, because the secondary chamber has an
excess-air environment, when the temperature is too high (above
the setpoint), the damper is opened to admit more air, and when
it is too low (below the setpoint), the damper is shut to limit
the air supply.
4.5.4 Ash Removal and Handling
Ash removal and handling systems may be classified as
continuous or periodic. Continuous ash removal systems are used
on continuous-duty MWI's, including rotary kiln MWI's. These
continuous ash removal systems may be dry or wet processes. In
either system, ash falls off the end of the hearth or kiln into
an ash discharge chute. In the dry system, the ash discharges
directly into an ash container positioned within an air-sealed
chamber. When the container is full, it is removed from the
chamber and replaced with an empty ash container. In the wet
process, the ash is discharged into a water pit. The water bath
quenches the ash, and it also forms an air seal with the
incinerator. A mechanical device, either a rake or a conveyor,
removes the ash from the quench pit intermittently or
continuously. The excess water is allowed to drain from the ash
as it is removed from the pit, and the wetted ash is discharged
into a collection container.
39
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Manual" ash removal typically involves removing ash by raking
and shoveling the ash into metal containers. Generally, this
removal occurs the morning after the burn, once the MWI has
cooled, and it is safe to remove the ash. Manual ash removal is
practiced on almost all MWI's without a continuous ash removal
system. Some systems include an ash ram that pushes some of the
ash from the incinerator. However, manual removal of the
remaining ash is still required in these units.
4.5.5 Energy Recovery
The heat generated during incineration can be recovered and
used to generate hot water or steam. The facilities that most
often recover heat from the stack gases are those with larger MWI
systems. Most often, a waste heat recovery boiler is installed
and used to generate steam and/or hot water. However, heat
exchangers are also used to recover heat.
Incinerator manufacturers often provide waste heat boilers
as an option with their incineration units. Figure 11 is a
schematic of an MWI with a waste heat recovery boiler. The
combustion gases from the incinerator pass through the waste heat
boiler prior to being emitted to the atmosphere. When a waste
heat boiler is used, an induced draft fan must be added to move
air through the system.
Heat exchangers are sometimes used to cool the hot secondary
chamber exhaust gases before they enter an air pollution control
system. These systems are used for situations in which space
limitations and/or economics prevent the installation of a waste
heat boiler for energy-recovery purposes.
4.5.6 Bypass Stack
An emergency bypass stack is typically added to an MWI when
a waste heat boiler (or an air pollution control system) is
included as part of the system. Because a waste heat boiler
causes a resistance (blockage to airflow) in the system if the
induced draft fan stops, pressure can build up in the incinerator
if the hot gases cannot escape quickly enough. The bypass stack
is added to allow a route for the hot gases to escape should the
fan fail. In other words, it allows the incinerator to go back
40
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Bypass
Stack
Bypass
Shutoff
Valve
Gas Flow
Stack
Incinerator
Waste Heat
Boiler
Damper
ID
Fan
Figure 11.
MWI with a waste heat recovery boiler
and bypass stack.
41
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to a natural draft system. The bypass stack is also used in
cases where the boiler must be bypassed for safety reasons or
operational upset conditions (e.g., loss of water flow to the
boiler, causing heat buildup). Another purpose of the bypass
stack is to protect the 'air pollution control device when a
system malfunction could result in damage to the device. The
combustion gases can be routed through the bypass stack to avoid
contact with the control device in these cases.
The bypass stack usually contains a damper valve to control
direction of the gas flow or a cap on top of the stack to prevent
air from being pulled into the system when the fan is operating.
If the bypass must be activated, the damper or cap is opened
automatically by some type of sensor; for example, if the fan
speed falls below a preset level, the bypass opens. Figure 11,
the schematic of an MWT with a waste heat boiler, illustrates a
typical position of the bypass stack in the duct between the
outlet of the secondary chamber and the waste heat boiler.
5.0 CHARACTERIZATION OF EMISSIONS
The pollutants emitted from MWI's include PM; metals;
organics, including CDD's and CDF's; CO; and the acid gases HC1,
S02, and NOX. These pollutants exist in the waste feed material
or are formed in the combustion process, but the primary point of
emissions release is the combustion stack (i.e., combustion gases
from the secondary chamber). Because of the high temperatures
typically encountered and because of the turbulent conditions and
adequate residence time in MWI's, pathogens are expected to be
completely destroyed in the combustion process. In addition to
stack emissions, there are potential sources of fugitive
emissions of these pollutants in the MWI process. Section 5.1
discusses the generation and emission of the pollutants from the
combustion process and from fugitive emission sources. The
various factors that affect emissions are discussed in
Section 5.2. Section 5.3 presents emission test data.
Section 5.4 presents existing emission limits (based on existing
requirements for MWI's).
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5.1 SOURCES OF EMISSIONS
5.1.1 Combustion Stack
Pollutants in the combustion gas stream from the secondary
chamber are emitted with the gases, through the stack. The
pollutants that are likely to be emitted through the stack as a
result of the combustion process are discussed in this section.
There are two types of PM: inerts (ash) and products of
incomplete combustion (soot). The noncombustible portion of the
waste feed represents those materials that will not burn under
any conditions in 'the incinerator. Emissions of noncombustible
materials result from the suspension or entrainment of ash by the
combustion air added to the primary chamber of the incinerator.
The more air added, the more likely that noncombustibles will
become entrained in the primary chamber and be emitted with the
flue gas. While entrainment is the primary mechanism for ash PM
emissions, soot formation also plays a role in PM emissions.
Soot, which is primarily elemental carbon, is a product of
incomplete combustion.
Metal emissions depend upon the characteristics of the feed
material. Metals may exist in the waste as parts of discarded
instruments or utensils; in plastics, paper, pigments, and inks;
or as discarded heavy metals used in laboratories. Trace metals
present in medical waste materials include lead, cadmium,
mercury, chromium, antimony, arsenic, barium, beryllium, nickel,
silver, and thallium. Emissions of these metals are generated
during the combustion process as a consequence of entrainment or
volatilization. Unlike organic constituents, metals are not
"destroyed" during the combustion process. Rather, they are
distributed or partitioned among the incinerator effluent
streams. As a result of this partitioning effect, metal
constituents can leave the primary chamber as bottom ash or in
the combustion gas. The relative distribution of the metals
between these streams is based on such factors as the chemical
form of the metals charged to the combustor, the localized
• reaction atmosphere in the primary chamber, localized chamber
temperatures, and localized airflows. Many metals are converted
43
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to oxides or chlorides during combustion and are emitted
primarily as entrained submicron- to micron-sized particles.
Metals that volatilize at primary combustion chamber temperatures.
may exit the system as a gaseous component of the air stream or
may selectively condense on small particles in the incinerator
combustion gas. Of the metals known to be present in medical
waste ash, the following are generally thought to exhibit such
fine-particle enrichment: arsenic, cadmium, chromium, nickel,
lead, and antimony.29
Complete combustion of organic materials results in the
formation of water (H2O) and carbon dioxide (CO2). The
concentration of CO in the incinerator exhaust gas stream is an
indicator of the combustion efficiency of the unit and is
primarily related to gas-phase combustion conditions in the
secondary chamber. Carbon monoxide is an intermediate product of
the reaction between carbonaceous fuels and oxygen. Combustion
conditions that result in incomplete combustion produce elevated
levels of CO, as well as PM and organics.
Inadequate gas-phase combustion conditions in the secondary
chamber also favor increased organic emissions. While these
emissions can originate directly from the vaporization of organic
material present in the waste, new organic species can be formed
during combustion as a result of the complex chemical reactions
occurring during the combustion process. When chlorine is
available (for example, from PVC or other chlorinated plastics),
the organics generated can include highly toxic chlorinated
organics, such as CDD's and CDF's.
Nitrogen enters the MWI as a constituent of auxiliary fuels,
as the chemical compounds found in the waste material, and as N2
in the combustion air. Nitrogen oxides are primarily formed from
the reaction of the N2 in the combustion air with oxygen or
oxygenated species, and the resultant product is referred to as
thermal NOX. .
The principal acid gas from MWI's is HC1. The determining
factor in HC1 formation and emissions is the availability of
chlorine in the feed material. In the presence of available
44
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hydrogen, as would occur in medical waste materials with high
organic contents, most of the available chlorine is converted to
HC1; however, low levels of elemental chlorine do exist in the,
exhaust gas. Most of the sulfur in the medical wastes is
converted to S02 during combustion, regardless of incinerator
design or operation.
5.1.2 Fugitive Emissions
There are three types of fugitive emissions: combustion
gases (including unburned volatile materials), PM, and pathogens.
Emissions of combustion gases can occur when charging wastes into
the incinerator and from leakage through improperly sealed doors.
Fugitive emissions of combustion gases may also accumulate in
poorly ventilated areas around the primary chamber. Fugitive
emissions of PM can occur when handling incinerator ash and when
handling and transporting the residue from air pollution control
devices (e.g., fabric filters). A potential source of fugitive
pathogen emissions is handling unburned medical waste. However,
careful handling of medical waste, not overfilling the plastic
bags containing the waste, the use of containers on wheels with
structural integrity to transport waste, and the use of automated
waste charging systems should reduce fugitive pathogen emissions
to negligible levels.
Fugitive emissions from the operation of an MWI are usually
the result of poor design, operation, or maintenance. Manually
fed MWI's are considered to be poor designs from an emissions
standpoint because the charging door must be opened to the
atmosphere during charging. The "air-lock" feature of ram-fed
MWI's helps to alleviate the fugitive emissions problem by
eliminating the need to have the primary chamber open directly to
the atmosphere. Proper precautions when handling waste and ash
reduce the potential for fugitive emissions. For example,
wetting or covering the ash or control device catch before
transporting can minimize the possibility of windblown fugitives.
Adequate maintenance of door seals, flanges, and auxiliary burner
housings also help reduce the possibility of leakage of gaseous
emissions to the atmosphere.
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5.2 FACTORS THAT-AFFECT EMISSIONS
The formation, generation, and emissions of all of the
pollutants discussed in Section 5.1 depend upon either the
availability of certain materials in the waste feed (i.e., waste
characteristics) or on the efficiency of the combustion process.
Factors involved in combustion process efficiency include MWI
system design, operating parameters, startup and shutdown
procedures, proper training of the operators, and how well the
system has been maintained. These factors are discussed in this
section.
5.2.1 Waste Characteristics
As discussed in Section 3.1, medical waste varies
considerably in composition and, therefore, in chemical and
physical characteristics. Waste characteristics can affect
combustion efficiency and pollutant formation. The chemical
composition of the waste materials is an important factor in
generating emissions. The presence of metals, halogenated
materials, and sulfur in the waste feed increases the potential
for emissions of PM, metals, organics, S02/ and HC1. Medical
waste incinerators are designed to operate under certain
conditions, including specific physical attributes of the waste
feed. These attributes (e.g., heat content, moisture content,
and bulk density) influence MWI feed rates, temperatures, air
flow conditions, and residence times - all of which affect
emissions of PM, metals, organics, CO, and NOX. If the physical
attributes of the waste vary from the design specifications, then
the potential for emissions can be affected.
5.2.2 Incinerator Operating Characteristics
Complete combustion of combustible material requires proper
control of feed charging procedures, temperatures, excess air,
turbulence, mixing, and residence time. Because of the
variability of "the physical properties of medical wastes,
incinerator operating parameters need to be adjusted to match the
composition of the waste in order to maximize combustion
efficiency. In general, increased temperatures and excess air
rates, good mixing, and longer residence times in the secondary
46
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chamber result in improved combustion efficiency and lower
emissions of PM, toxic organics, and CO. However, incinerator
operating parameters have little or no effect on emissions of HC1
and S02. (It should be noted that although the MWI operator can
control feed charging, temperatures, and excess air rates, an
operator has only indirect control over turbulence, mixing, and
residence times.)
Waste handling and charging procedures may account, in part,
for fugitive emission sources. For example, emptying medical
waste from its container into the incinerator (instead of leaving
it in a disposable container that can be loaded into the
incinerator) may result in spillage. Waste charging activities
often include segregating wastes and, therefore, can influence
the composition of the feed material, incinerator operating
conditions, and subsequent stack and fugitive emission
characteristics. Systems with automatic feeders usually have
controls to prevent overfeeding, but in manually fed and batch
units, overfeeding can occur. Overfeeding the primary chamber
can result in blockage of the air port to the secondary chamber,
premature ignition of the waste, and excessive emissions because
the rapid generation of volatiles can exceed the capacity of the
secondary chamber. Feed volumes and frequency (determined by the
waste composition) are responsible for variations in chamber
temperatures,-which, in turn, affect combustion efficiency and
emission profiles.
Temperatures in the primary chamber must be high enough to
sustain combustion and to generate sufficient volatile combustion
gases. Inadequate temperatures may result in increased emissions
of PM, CO, and organics. Temperature also plays a role in the
volatilization of metals and the subsequent emission of these as
gaseous components of the air stream. Temperatures must be high
enough to destroy pathogens and combust fixed carbon.
Adjustments that increase combustion temperatures may, however,
increase emissions of NOX and trace metals.
The quantity and distribution of combustion air is another
operating characteristic that affects emissions. The rate of
47
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entrainment" of ash in the combustion air added to the primary
chamber is likely to increase as more air is added, resulting in
a higher rate of PM-entrained trace metal emissions. On the
other hand, low excess-air conditions in the secondary chamber
can result in soot emissions. Oxygen concentration and the
degree of mixing of the air with the fuel has a direct impact on
CO formation. Emissions of organics increase with poor air
distribution in the waste bed and inadequate combustion air
conditions in the secondary chamber. As airflow rates increase,
the residence times in the secondary chamber decrease.
Residence times in the secondary chamber have an impact on
emissions. Organic materials present in the medical waste
material must be exposed to optimum temperatures long enough to
ensure their complete combustion. Emissions of organic species
formed as by-products of combustion (e.g., CDD's and CDF's) are
affected by the residence times in the secondary chamber if they
have already been formed.
5.2.3 System Design
Manual control of air modulation and primary and secondary
chamber burner modulation does not always result in effective
control of the combustion process. Because proper combustion air
rate and chamber temperatures are critical to combustion
efficiency, the inability to closely monitor and control these
key parameters can result in higher pollutant emissions.
Residence time requirements establish constraints on the
size and shape of the secondary chamber. The secondary chamber
is sized to provide the desired residence time based on the flow
rate for which the unit is designed. Using a unit with a
secondary chamber whose volume is insufficient to accept and
completely oxidize all volatile gases generated in the primary
chamber can contribute to pollutant emissions. As discussed in
Section 5.2.2, 'residence times in the secondary chamber play a
critical role in the reduction of emissions of PM, CO, and
organics.
For MWI's, the distribution of combustion air between the
primary and secondary chambers is a key operating consideration.
48
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Air distribution affects the amount of oxygen that is available
for reaction in each chamber and, therefore, influences
combustion efficiency and subsequent air emissions.
'When MWI's are not designed to include effective mechanisms
for promoting the mixing of solids in the primary chamber,
burnout may not be complete. Mechanical turbulence of the bed
may be used to expose all of the solid waste to oxygen, thereby
enhancing the degree of burnout. Various hearth designs and ram
systems are used to accomplish mechanical turbulence. While
effective mixing o'f solids maximizes combustion efficiency,
increased emissions of PM may occur as a result of the
turbulence.
The size of burners specified for MWI's also affects
emissions. The burners provide the heat required to initially
ignite the waste, to sustain combustion of the charged waste, and
to complete the vapor-phase combustion. Burners are designed to
provide a rated heat input expressed in kJ/hr (Btu/hr).
Specifying improper burner sizes can result in incomplete
combustion and a consequent increase in emissions.
For MWI systems that are designed without automated ash
removal and handling systems, the repeated manual opening and
closing of the ash cleanout door and tightening of the door
clamps may damage the seal gasket, which can allow infiltration
of outside air around the door face. This infiltration may
result in decreased combustion efficiency and a subsequent
increase in emissions.
5.2.4 Startup and Shutdown Procedures
Startup and shutdown of a MWI involves special procedures
that vary depending upon the type of unit. Included in the
startup procedures are charging the waste, preheating the
secondary chamber, and activating the combustion air blowers.
Startup procedures for batch-feed units also include removing the
ash from the previous cycle and sealing the charge door.
Shutdown of a continuous-duty incinerator involves stopping the
charging process and maintaining temperatures in the secondary
chamber until the remaining waste burns down to ash and is
49
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discharged from the system. For intermittent-duty and batch-feed
units, shutdown procedures include increasing the combustion air
level in the primary chamber and maintaining the temperature in
that chamber at a minimum setting for a predetermined length of
time to ensure that the fixed carbon is combusted. In addition,
the secondary chamber temperature is maintained at a level
sufficient to complete the vapor phase combustion of material
exiting the primary chamber. When this burndown period is
.complete, the cooldown period is initiated. If not conducted
properly, any of these startup or shutdown procedures may result
in increased emissions. These emissions could occur as a direct
result of the procedure (e.g., removing ash or charging the
waste) or as an indirect result, i.e., reduced combustion
efficiency.
5.2.5 Operator Training
The success of incineration as a technique for treating
medical waste depends on the proper operation of the incinerator.
The operator is in control of many of the factors that affect the
performance of an MWI, including: (1) waste charging procedures,
(2) incinerator startup and shutdown, (3) monitoring and
adjusting operating parameters, and (4) ash handling. An
operator without adequate training will probably not be
sufficiently aware of the relationship between MWI process
components and potential air pollution problems to be able to
avoid or minimize these problems.
5.2.6 Preventive Maintenance
Without an effective MWI preventive maintenance program, the
frequency of inefficient operation conditions, upset situations,
and air pollution episodes increases. Observations made during
the EPA emissions testing program illustrate the importance of an
effective maintenance program. At one facility, the lack of
routine maintenance was reflected in inoperative burners,
malfunctioning relays, clogged air ports, cross-wired lead wires
in the control box, improperly wired thermocouple assemblies with
chipped insulation, and several other conditions that resulted in
a poorly operated unit. These conditions contributed to the
50
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unit's severely limited burning capacity, very poor burnout of
waste, and a greater amount of visible emissions than would
normally be expected. At another site; maintenance-related
problems included malfunctioning hydraulic cylinders and pumps in
the automatic ram system and a problem with the switch on the
gate in that system. These problems caused the gate to remain
open after the ram cycle was completed and, because of the
disruption of airflow, increased visible stack emissions.
Problems at a third site involved a disabled primary chamber
underfire control damper, a nonfunctional control arm on a
secondary chamber air blower modulation damper, and seals in need
of replacement. Additional maintenance-related conditions
included an improperly programmed process control loop, which
caused the hopper lid to open too soon after the charging ram
retracted. Each of these' circumstances contributed to
substandard operating conditions and, therefore, resulted in
increased emissions.
5.3 EMISSION RATES
During the development of background information on MWI's,
numerous emissions test reports and test report summaries were
obtained. Approximately 25 of these reports and report summaries
provide emission test data. For test data to be most useful,
certain information on the MWI process design and operating
conditions, as well as details on the test methods used for
testing, must also be available. In almost every case, the test
reports obtained were incomplete, in that information on the
design and operation of the MWI during testing was not provided.
Table 5 .presents the post-combustion emission rates (i.e., in the
stack for facilities without an pollution control device and
between the incinerator and air pollution control device at other
sites) for eight tests that were performed at seven test sites as
part of EPA's MWI test program. The emission rates are presented
in three different formats: Table 5a is presented in metric
units; Table 5b is presented in English units; and Table 5c is
presented in pounds of emissions per year. ,
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TABLE 5a. POST-COMBUSTION EMISSION RATES FOR MEDICAL
WASTE INCINERATORS
(Metric Units)
Pollutant, at 7 percent O?
PM, mg/dscm
CO, ppmv
2,3,7,8-TCDD, ng/dscm
Total CDD, ng/dscm
2,3,7,8-TCDF, ng/dscm
Total CDF, ng/dEcm
Total CDD + CDF, ng/dscm
HC1, ppmv
SOj, ppmv
NOT, ppmv
Antimony, fig/dscm
Arsenic, ^g/dscm
Barium, ^g/dscm
Beryllium, ^g/dscm
Cadmium, pg/dscm
Chromium, jig/dscm
Iron, /ig/dscm
Lead, jig/dscm
Manganese, /tg/dscm
Mercury, /ig/dscm
Nickel, /ig/dccm
Silver, jig/dscm
Thallium, pg/dscm
A
358
297
3.58
717
13.8
3,741
4,458
1,308
23
• 83
1,578
17.9
384.7
0.22
416
31.3
NM
5,420
NM
1,111
10
12.2
198
B
593
529
15.3
2,843
66.9
14,598
17,440.
1,470
13
86
1,089
13.1
143'.8
0.12
261
41.5
NM
2,774
NM
861
32
7.4
3.3
C
1,030
1,213
29.4
5,050
80.1
19,700
24,700
1,537
42.8
182
612
11.1
86.2
1.11
55
36.3
NM
1,878
NM
7.96
25.8
14.2
5.4
D
227
14
0.2
94
0.91
343
437
1,714
8
180
NM
14.4
NM
NM
298
19
434
4,643
103
6,024
10
NM
NM
E
230
26
0.27
319
0.88
1,133
1,451
NM
1.5
72
NM
28
NM
NM
385
53.0
1,497
3,317
191
366
39
NM
NM
F
105
108
0.85
226
4.2
520
745
117
114
354
101
63.6
26.8
0.21
140
108
NM
485
NM
121
164
3.4
5.8
G
35
10
0.46
137
2.3
487
623
198
17
85
63
2.6
43.5
0.10
118
19.7
NM
3,174
NM
2,326
11
2.8
1.0
H
1,125
11.7
0.02
24
0.633
171
195
950
14
84
662
10.6
2,825
1.56
482
141
NM
4,000
NM
2,609
114
3.7
16.1
NM = Not Measured
A: 140 Kg/hr; general medical waste; intermittent, ram-fed; 1-sec residence time in secondary (average of nine test runs).
B: 140 Kg/hr; general medical waste; intermittent, ram-fed; 0.33-sec residence time in secondary (average of nine test runs).
C: 110 Kg/hr; general medical waste; intermittent, manually-fed; 0.2-sec residence time in secondary (average of three test runs).
D: 330 Kg/hr; general medical waste; intermittent, ram-fed; 1.6-sec residence time in secondary (average of 21 test runs).
E: 680 Kg/hr; general medical waste; continuous, ram-fed; 2-sec residence time in secondary (average of three test runs).
F: 80 Kg/hr; pathological waste; intermittent, manually-fed; 0.2-sec residence time in secondary (average of six test runs).
O: 340 Kg/batch; general medical waste; batch-feed; 1.75-sec residence time in secondary chamber (average of six test runs).
H: 365 Kg/hr; general medical waste; continuous, ram-fed; 2.2-sec residence time in secondary chamber (average of six test runs).
52
-------
TABLE 5b. POST-COMBUSTION EMISSION RATES FOR MEDICAL
WASTE INCINERATORS
(English Units)
Pollutant, at 7 percent O7
PM, gr/dscf
CO, ppmv
2,3,7,8-TCDD, gr/dscf (10-9)
Total CDD, gr/dscf (10-9)
2,3,7,8-TCDF, gr/dscf (10-9)
Total CDF, gr/dscf (10-9)
Total CDD + CDF, gr/dscf
(10-9)
HC1, ppmv
SO-?, ppmv
NOV, ppmv
Antimony, gr/dscf (10"6)
Arsenic, gr/dscf (10'6)
Barium, gr/dscf (10"6)
Beryllium, gr/dscf (10'6)
Cadmium, gr/dscf (1CT6)
Chromium, gr/dscf (10~°)
Iron, gr/dscf (iO"6)
Lead, gr/dscf (IO-6)
Manganese, gr/dscf (1CT6)
Mercury, gr/dscf (10*6)
Nickel, gr/dscf (1CT6)
Silver, gr/dscf (ID*6)
Thallium, gr/dscf (ICT6)
A
0.157
297
1.56
3.13
6.03
1,635
1,948
1,308
23.1
83
690
7.8
168
0.09
182
13.7
NM
2,368
NM
485
4.5
5.3
86.7
B
0.259
529
6.67
1,242
29.25
6,379
7,621
1,470
12.6
86
476
5.7
63
0.05
114
18.1
NM
1,212
NM
376
14.1
3.2
1.43
C
0.451
1,213
12.8
2,207
35
8,610
10,800
1,537
42.8
182
270
4.9
38
0.5
24
16
NM
820
NM
3.5
11.3
6.2
2.4
D
0.099
14
0.09
41
0.40
150
191
1,714
7.5
180
NM
6.3
NM
NM
130
8.3
190
2,029
44.9
2,632
4.5
NM
NM
E
0.100
26
0.12
139
0.39
495
634
NM
1.5
72
NM
12.3
NM
NM
16~8
23.1
654
1,449
83.5
160
16.8
NM
NM
F
0.046
108
0.35
99
1.7
227
326
117
114
354
45
28
12
0.09
62
48
NM
210
NM
53
72
1.5
2.6
G
0.015
10
0.20
60
1.01
213
272
198
16.9
85
28
1.1
19
0.04
52
8.6
NM
1,387
NM
1,016
4.9
1.2
0.43
H
0.490
11.7
0.01
11
0.28
75
85
950
14
84
289
4.6
1,234
0.68
210
62
NM
1,748
NM
1,140
50
1.6
7.04
NM = Not Measured
300 Ib/hr; general medical waste; intermittent, ram-fed; 1-sec residence time in secondary (average of nine test runs).
300 Ib/hr; general medical waste; intermittent, ram-fed; 0.33-sec residence time in secondary (average of nine test runs).
A:
B:
C: 250 Ib/hr; general medical waste; intermittent, manually-fed; 0.2-sec residence time in secondary (average of three test runs).
D: 720 Ib/hr; gemeral medical waste; intermittent, ram-fed; 1.6-sec residence time in secondary Average of 21 test runs).
E: 1,500 Ib/hr; general medical waste; continuous, ram-fed; 2-sec residence time in secondary (average of three test runs).
F: 175 Ib/hr; pathological waste; intermittent, manually-fed; 0.2-sec residence time in secondary (average of six test runs).
G: 750 Ib/batch; general medical waste; batch-feed; 1.75-sec residence time in secondary chamber (average of six test runs).
H: 800 Ib/hr; general medical waste; continuous, ram-fed; 2.2-sec residence time in secondary chamber (average of six test runs).
53
-------
TABLE 5c. POST-COMBUSTION EMISSION
WASTE INCINERATORS
(Pounds Per Year)
RATES FOR MEDICAL
Pollutant
PM
CO
2,3,7,8-TCDD, (10"3)
Total CDD, (ID'3)
2,3,7,8-TCDF, (10'3)
Total CDF, (lO'3)
Total CDD + CDF, (10"3)
HC1
SOj
NOX
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Lead
Mercury
Nickel
Silver
Thallium
A
1,270
1,200
0.015,
2.5
0.05
13
16
6,800
215
550
6
0.07
1.4
<0.01
' 1.5
0.12
20
4.0
0.04
0.05
0.7
B
2,200
2,100
0.05
10
0.2
52
62
8,000
120
580
3.8
0.05
0.5
<0.01
0.9
0.14
9.5
3.1
0.1
0.05
0.01
C
3,650
4,900
0.1
18
0.3
70
90
8,000
395
1,200
2.2
0.04
0.31
<0.01
0.2
0.13
6.5
0.03
0.1
0.05
0.02
D
3,000
220
<0.01
1.2
<0.01
5.2
6.4
32,230
270
4,400
NM
0.18
NM
NM
4.0
0.26
59
77
0.13
NM
NM
E
4,940
610
0.09
7
0.02
29
36
NM
85
3,150
NM
0.6
NM
NM
8.0
1.2
70
8.3
0.9
NM
NM
F
375
435
<0.01
0.8
0.02
1.8
2.6
600
1,050
2,350
0.35
0.23
0.09
<0.01
0.5
0.38
1.8
0.43
0.6
0.01
0.02
G
108
35
<0.01
0.4
<0.01
1.5
1.9
890
138
477
0.2
<0.01
0.14
<0.01
0.4
0.06
10
7.3
0.04
<0.01
<0.01
H
40,095
576
0.0007
0.8
0.02
5.7
6.6
804
1,575
4,428
23.8
0.38
101
0.06
17.3
5.08
144
95
4.12
0.13
0.56
NM = Not Measured
A: 300 Ib/hr; general medical waste; intermittent, ram-fed; 1-sec residence time in secondary (average of nine test runs).
B: 300 Ib/hr; general medical waste; intermittent, ram-fed; 0.33-sec residence time in secondary (average of nine test runs).
C: 250 Ib/hr; general medical waste; intermittent, manually-fed; 0.2-sec residence time in secondary (average of three test runs).
D: 720 Ib/hr; general medical waste; intermittent, ram-fed; 1.6-sec residence time in secondary (average of 21 test runs).
E: 1,500 Ib/hr; general medical waste; continuous, ram-fed; 2-sec residence time in secondary (average of three test runs).
F: 175 Ib/hr; pathological waste; intermittent, manually-fed; 0.2-sec residence time in secondary (average of six test runs).
G: 750 Ib/batch; general medical waste; batch-feed; 1.75-sec residence time in secondary chamber (average of six test runs).
H: 800 Ib/hr; general medical waste; continuous, ram-fed; 2.2-sec residence time in secondary chamber (average of six test runs).
54
-------
The MWI's tested as part of the EPA test program range in
size from about 110 kg/hr (250 Ib/hr) to about 680 kg/hr
(1,500 Ib/hr). One unit is a batch-feed MWI with a capacity of
about 340 kg/batch (750 Ib/batch). The smallest unit is a
manually-fed, intermittent-duty MWI that can incinerate
nonpathological (general medical) waste or pathological waste,
and the largest unit is a continuous-duty MWI with automatic
feeding. The secondary chamber residence times range from about
0.2 sec to 2.0 sec. Five different MWI manufacturers' products
were tested during the test program. Units A, B, and D were
tested over a wide range of waste feed charging conditions.
As can be seen in Table 5, the degree of variation in
emissions from unit to unit is much greater for some pollutants
than for others. For the pollutants that are'directly impacted
by the secondary chamber designs (PM, CO, and CDD + CDF), units
D, E, and G show a significant improvement over units B and C.
The secondary chamber residence time for units D, E, and G is
about 1.6 to 2.0 sec, whereas for units B and C, the time
averages about 0.2 sec. Emissions from unit A, with a 1.0 sec
residence time, are between the averages for the other units.
Emission rates for pollutants that are largely unaffected by
secondary chamber conditions (HC1, S02, NOX, and metals) are
dependent on the characteristics of the waste. Pollutants such
•as arsenic, chromium, lead, and nickel vary only slightly among
the six MWI's burning general medical waste. Some other
pollutants such as mercury, cadmium, and thallium show
significant variations from site to site. These variations are
apparently a function of the practices of the hospitals with
respect to purchase and disposal of items that contain these
pollutants.
Average post combustion emission rates were calculated based
on the measured emission rates from the eight EPA tests to
present the reader with an understanding of the magnitude of
• emission rates from MWI's. These averages are presented in
, Tables 6a (Metric units) and 6b (English units).
55
-------
TABLE 6a. AVERAGE POST-COMBUSTION EMISSION RATES FOR MEDICAL
WASTE INCINERATORS
(METRIC UNITS, @ 7 PERCENT 0?)
PM, mg/dscm
CO , ppmv
2,3,7,8-TCDD, ng/dscm
Total CDD, ng/dscm
2,3,7,8 -TCDF, ng/dscm
Total CDF, ng/dscm
Total CDD + CDF, ng/dscm
HC1 , ppmv
SO? , ppmv
NOY/ ppmv
Antimony, jig/dscm
Arsenic, /xg/dscm
Barium, /zg/dscm
Berylium, ^g/dscm
Cadmium, /zg/dscm
Chromium, /zg/dscm
Iron, /zg/dscm
Lead, jig/dscm
Manganese, /^g/dscm
Mercury, /zg/dscm
Nickel, ng/dscm
Silver, /zg/dscm
Thallium, /zg/dscm
Range
35-1,125
10-1,210
0.02-29.4
24-5,050
0.63-80.1
171-19,700
195-24,700
117-1,714
1.5-114
72-354
63-1,580
2.6-63.6
26.8-2,825
0.10-1.56
55-482
19.0-141
434-1,500
485-5,420
103-191
7.96-6,024
10-164
2.8-14.2
1.0-198
Average
463
276
6.17
1,176
21.3
5,087
6,256
1,044
29.1
141
636
20.1
473
0.50
269
56.2
966
3,212
147
1,678
50.7
7.5
39.4
56
-------
TABLE 6b." AVERAGE POST-COMBUSTION EMISSION RATES FOR MEDICAL
WASTE INCINERATORS
(ENGLISH UNITS, @ 7 PERCENT 0?)
PM, gr/dscf
CO , ppmv
2,3,7,8-TCDD, gr/dscf (10-9)
Total CDD, gr/dscf (10-9)
2,3,7,8 -TCDF, gr/dscf (10"9)
Total CDF, gr/dscf (10~9)
Total CDD + CDF, gr/dscf (10" 9)
HC1 ,. ppmv
S09 , ppmv
NOY, ppmv
Antimony, gr/dscf (10~6)
Arsenic, gr/dscf (10~6)
Barium, gr/dscf (10~6)
Berylium, gr/dscf (10~6)
Cadmium, gr/dscf (10~°)
Chromium, gr/dscf (10 )
Iron, gr/dscf (10~6)
Lead, gr/dscf (10" 6)
Manganese, gr/dscf (10~6)
Mercury, gr/dscf (10~6)
Nickel, gr/dscf (10 ~6)
Silver, gr/dscf (10"6)
Thallium, gr/dscf (10" 6)
Range
0.015-0.482
10-1,210
0.009-12.8
0.80-2,210
0.28-35.0
75-8,610
85-10,800
117-1,714
1.5-114
72-354
28-690
1.1-28
12-1,332
0.04-0.7
24-210
8.6-62
190-654
210-2,370
44.9-83.5
3.5-2,630
4.5-72
1.2-6.2
0.43-86.7
Average
0.20
276
2.72
474
9.2
2,223
2,735
1,044
29.1
141
300
8.82
206
0.22
118
24.7
422
1,403
64.2
733
22.2
3.26
17.2
57
-------
5.4 EXISTING EMISSION LIMITS
The majority of the States have promulgated or are proposing
regulations or permit guidelines specific to MWI's. Tables 7 and
8 summarize this regulatory activity for new and existing units,
respectively. Proposed and final regulations, as well as
applicable guidelines, have been included.
The State regulations are generally very complex, and many
are in the process of being revised. There is a wide variability
in the requirements from State to State. This variability
extends to regulatory format, pollutants addressed, emission
limits, affected facility definition, size cutoffs, and operating
parameters. For example, some State limits are expressed in
terms of pounds of PM per pound of waste charged to the
incinerator (Ib/lb), while others are expressed in terms of
grains of PM per dry standard cubic foot (gr/dscf) of stack gas.
Some States use permit conditions rather than formal regulations,
and even these may vary from site to site.
While the most frequently regulated pollutants are PM and
HC1, the range of the emission limits is very wide. For PM, the
range covers an order of magnitude. In the case of HC1, not only
is there a wide range of requirements for emission reduction, but
the emission limits are expressed in many different formats,
including percent reduction, Ib/hr, and parts per million dry
volume (ppmdv).
Frequently, States have different emission limits for
different sizes or capacities of incinerators. Two- and three-
tiered regulations are not uncommon. In many States the emission
limits on some or all MWI's can be achieved without add-on
controls. The levels at which size cutoffs are established are
not consistent among the States. Furthermore, an incinerator may
be subject to different regulations depending on the age of the
unit and the type of waste burned.
The States have established a wide variety of equipment and
operating standards for MWI's to ensure proper operation. These
standards include various minimum secondary chamber temperatures
and gas residence times, minimum primary chamber temperatures,
58
-------
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and required interlock systems to prevent waste charging when the
chamber temperature is below a specified value. These standards
vary from State to State and may be tiered for different
incinerator sizes. Several states also have requirements for
operator training programs.
6.0 REFERENCES
1. U.S. Environmental Protection Agency. EPA Guide for
Infectious Waste Management. EPA/530-SW-86-014. (NTIS
PB86-199130) U.S. EPA Office of Solid Waste. May 1986.
2. U.S. Environmental Protection Agency. Standards for the
Tracking and Management of-Medical Waste: Interim Final Rule
and Request for Comments. Washington, B.C. Federal
Register 54:12373, 12374. March 24, 1989.
3. Ontario Ministry of the Environment. Incinerator Design and
Operating Criteria, Volume II - Biomedical Waste
Incineration. October 1986.
4. Barbeito, M. and M. Shapiro. "Microbiological Safety
Evaluation of a Solid and Liquid Pathological Incinerator."
Journal of Medical Primatology, Vol 6, 264-273. 1977.
5. McRee, R. Operation and Maintenance of Controlled-Air
Incinerators. Ecolaire Combustion Products. (Undated).
6. Letter and attachments from R. Massey, Consumat Systems,
Inc., to J. Farmer, U.S. Environmental Protection Agency.
February 1990. Response to Section 114 information request
to MWI manufacturers.
7. Letter and attachments from G. Swann, Joy Energy Systems,
Inc., to J. Farmer, U.S. Environmental Protection Agency.
February 23, 1990. Response to Section 114 information
request to MWI manufacturers.
8. Letter and attachments from K. Wright, John Zink, to
J. Farmer, U.S. Environmental Protection Agency. March 2,
1990. Response to Section 114 information request to MWI
manufacturers.
9. Memorandum from D. Randall, MRI, to Project File. April_30,
1992. Summary of data provided by hospitals and commercial
facilities in response to Section 114 information request.
10. Memorandum from D. Randall and T. Holloway, MRI, to Project
File. April 30, 1992. Summary of process data from EPA and
non-EPA emission tests.
73
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11. Letter" and attachments from T. Kendron, Simonds
Manufacturing Corp., to J. Farmer, U. S. Environmental
Protection Agency. April 9, 1990. Response to Section 114
information request to MWI manufacturers.
12. Letter and attachments from J. Basic, Sr., John Basic, Inc.,
to J. Farmer, U.S. Environmental Protection Agency.
February 26, 1990. Response to Section 114 information
request to MWI manufacturers.
13. Memorandum from D. Kapella, MRI, to J. Eddinger, EPArlSB.
Draft trip report: MediWaste, West Babylon, New York.
January 12, 1990.
14. Telecon: M. Cassidy, MRI, with J. McCarthy, Air Pollution
Control District of Jefferson County. November 13, 1989.
15. Draft Report: Medical Waste Incineration Practices in
Municipal Waste Combustors. U.S. Environmental Protection
Agency. March 15, 1989. .
16. Survey of Medical Waste Incinerators in the State of
Washington.
17. Letter and attachments from D. Brown, Consertherm Systems,
Inc., to J. Farmer, U.S. Environmental Protection Agency.
March 23, 1990. Response to Section 114 information
request.
18. Data base of responses from incinerator owner/operators to
Medical Waste Tracking Act request for information.
19. Telecon. M. Cassidy, MRI, with A. Vasquez, Colorado
Department of Health. October 26, 1989. List of MWI's in
Colorado...
20. Air Pollution Source Management System, Current Application
Data List, Hospital Incinerator List. Compiled by New York
State Department of Environmental Conservation, Albany, New
York.
21. Listing of Incinerators in the State of New Jersey.
Compiled by New Jersey Department of Environmental
Protection, Trenton, New Jersey.
22. Telecon. E. Ball, MRI, with R. Zanni, Consertherm Systems,
Inc. December 8, 1989. Charging capacity and operating
parameters of rotary kiln combustors used as MWI's.
23. Undated Brochure Advertising Product Line; Consumat Systems,
Inc., Richmond, Virginia.
74
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24. Block, S. and J. Netherton. Disinfection, Sterilization,
and Preservation. Second Edition. 1977. p. 730.
25. Doucet, L. Section 12/Chapter 14. In: NFPA Fire
Protection Handbook. 16th Edition, p. 12-116.
26. Undated Brochure Advertising Product Line; Morse Boulger,
Inc., Glen Cove, New York.
27. Undated Brochure Advertising Product Line; Basic
Environmental Engineering, Inc., Glen Ellyn, Illinois.
28. Personal conversation between R. Neulicht, MRI, and G. Swan,
Ecolaire Combustion Products, and J. Kidd, Cleaver Brooks.
February 22, 1989. Variations in Designs of MWI Primary
Chambers.
29. U. S. Environmental Protection Agency. Hospital Waste
Combustion Study: Data Gathering Phase, EPA-450/3-88-017.
December 1988.
30. Environment Reporter. State Air Laws. Volume 1. Alabama
Air Pollution Regulations, as amended October 30, 1992.
Department of Environmental Management. Division 3.
Section 335-3-3.04. Bureau of National Affairs.
31. Siebert, P., and V. Straub. Survey of State Air Regulations
on Medical Waste Incinerators. Air and Waste Management
Association. June 1993.
32. Telecon. Jurczak, D., MRI, with Mohan, S., Arizona
Department of Environmental Quality. September 14, 1993.
Information on Arizona medical waste incinerator
regulations.
33. Telecon. Jurczak, D., MRI, with Notron, R. , Arkansas
Department of Pollution Control. September 14, 1993.
Information on Arkansas medical waste incinerator
regulations.
34. State of California, Air Resources Board. Section 93104,
Title 17: Dioxins Airborne Toxic Control Measures--Medical
Waste Incinerators.
35. State of Colorado Air Pollution Regulation #6 Part B, as
amended August 20, 1992. Sections III.V and III.VII.
36. District of Columbia. Incinerator Rule # 602, Particulate
Mater Rule # 603, Opacity Rule # 606, Sulfur Content of Fuel
Oils # 801, Nitrogen Oxide Emissions Rule # 804, and Odorous
or other Nuisance Air Pollutants Rule # 903.
75
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37. Environment Reporter. State Air Laws. Volume 2. Georgia
Air Quality Control Rules, as amended November 22, 1992.
Chapter 391-3-1. Section .02(2) (c). Bureau of National
Affairs.
38. Environment Reporter. State Air Laws. Volume 2. Idaho Air
Pollution Control Regulations, as amended August 21, 1992.
Title' 1, Chapter 01.01502 and 01.01503. Bureau of National
Affairs.
39. State of Illinois Regulation Subpart C: Incinerators
Section 216.141. Regulation Subpart D: Particulate Matter
Emissions from Incinerators Section 212.181.
40. Telecon. Jurczak, D., MRI, with Whitmer, D., Indiana
Department of Environmental Management. September 13, 1993.
Medical waste incinerator emission limits in Indiana.
41. Environment Reporter. State Air Laws. Volume 2. Iowa Air
Pollution Control Regulations, updated May 8, 1987.
Division 567, Title II, Chapter 23.4(12). Bureau of
National Affairs.
42. Environment Reporter. State Air Laws. Volume 2. Kansas
Air Pollution Emission Control Regulations, as updated
December 4, 1992. Title 28, Part 2, Chapter 28-19-31.
43. Environment Reporter. State Air Laws. Volume 3. Kentucky
Air Pollution Control Regulations. Title 401, Chapter KAR
59:023.
44. State of Louisiana. Department of Environmental Quality.
October 1992. Subchapter W, Section 1591.
45. State of Maryland. Air Toxics Regulation, July 1, 1988.
Regulation 26-11-15. BACT analysis and 26-11-08-09,
Incineration Operator Training.
46. State of Massachusetts. Department of Air Quality Control,
September 27, 1990. Interim Policy No. 90-005.
47. State of Minnesota. Proposed Permanent Rules Relating to
Waste Combustors; Standards of Performance. Chapter 7007,
7011, and 7017.
48. State of Mississippi. Air Pollution Control Regulations,
July 3, 1991. General Guidelines for Infectious Waste
Incineration.
49. State of Missouri. Air Pollution Control Regulations, as
updated October 6, 1992. Medical Waste and Solid Waste
Incinerators. Title 10, Division 10, Chapter 1, Section
10-6.160.
76
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50. Environment Reporter. State Air Laws. Volume 4. Montana
Air Quality Regulations, as amended December 4, 1992.
Titlel6, Chapter 8, Subchapter 14, Section 16.8.1406.
Bureau of National Affairs.
51. Environment Reporter. State Air Laws. Volume 4. Nebraska
Air Pollution Control Regulations, as updated August 30,
1991. Title 129, Chapter 6 and 11. Bureau of National
Affairs.
52. Environment Reporter. State Air Laws. Volume 4. Nevada
Air Quality Regulations, as updated October 23, 1992.
Chapter 445.754.
53. Environment Reporter. State Air Laws. Volume 4. New
Hampshire Air Resources Regulations, as updated June 21,
1991. Part ENV-A 1201. Bureau of National Affairs.
54. Environment Reporter. Volume 5. New Jersey Regulations on
Incinerators, as updated July 14, 1978. Chapter 27,
Subchapter 11, Section 7:27-11.3. Bureau of National
Affairs.
55. State of New Mexico. Air Regulations on Biomedical Waste
Combustion, as updated August 30, 1991. Regulation 2020,
Part IV.
56. Environment Reporter> State Air Laws. Volume 5. New York
Air Pollution Control Regulations, as updated February 8,
1991. Title 6, Chapter III, Subparts 219-3 and 219-5.
57. State of North Carolina. Environmental Health and Natural
Resources Air Regulations, as amended October 1, 1991.
Section .1200 - Control of Emissions from Incinerators.
58. State of Ohio. Infectious Waste Incinerator Emissions
Rules, as updated July 9, 1991. Title 3745, Chapter, 75.
59. Environment Reporter. State Air Laws. Volume 5. Puerto
Rico Air Regulations, June 12, 1981. Part IV. Rules 403 and
405. Bureau of National Affairs.
60. State of South Carolina Air Quality Standards, as updated
May 25, 1990. Regulation 62.5 Section III.
61. State of South Dakota. Department of Natural Resources, as
updated April 17, 1991. Chapter 74:35:01.
62. Environment Reporter. State Air Laws. Volume 6. Tennessee
Air Pollution Rules, as update November 15, 1991. Chapter
1200-3-16-04.
77
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63. Environment Reporter. State Air Laws. Volume 6. Texas Air
Control Board Regulations, as amended October 23, 1992.
Texas Regulation 1: Control of Air Pollution from Visible
Emissions and PM. Title 31, Part III Chapter II Section 121-
124. Bureau of National Affairs.
64. Utah Department of Environmental Quality Best Available
Control Technology.
65. Letter from Hull, P., EPA Region VIII, to Jordan, B.,
EPA:OAQPS. September 28, 1993. Summary of Typical Permit
Limits for Medical Waste Incinerators in EPA Region VIII.
66. State of Vermont. Air Pollution Control Regulations, as
updated January 20, 1993. Subchapter II Sections 5-211,
5-231, and 5-261.
67. State of Virginia. Air Pollution Control Board. Emergency
Regulations for the Control and Abatement of Air Pollution,
effective June 28, 1993. Part V: Standards of Performance
for Regulated Medical Waste Incinerators. Rule 5-6.
68. State of Washington. Air Pollution Control Regulations.
Chapter 173-400 WAC: Emissions Standards for Solid Waste
Incineration and Chapter 173-300 WAC: Certification of
Operators of Solid Waste Incinerators and Landfill
Facilities.
69. Environment Reporter. State Air Laws. Volume 6.
Washington Air Pollution Control Regulations, as amended
through March 22, 1991. Title 173. WAX Chapter 173-400-
040. Bureau of National Affairs.
70. Environment Reporter. State Air Laws. Volume 6. West
Virginia Air Pollution Control Regulations, as amended
May 6, 1991. Title 45, Series 6, Section 45-6-4.
71. State of Wisconsin. Air Pollution Control Guidelines,
January 1993. Facilities Burning Medical Waste.
72. Environment Reporter. State Air Laws. Volume 6. Wyoming
Air Quality Standards and Regulations, as amended
October 20, 1990. Chapter 1, Section 14.
73. Environment Reporter. State Air Laws. Volume 2. Colorado
New Source Performance Standards. June 18, 1992. Chapters
V and VII. Bureau of National Affairs.
74. Environment Reporter. State Air Laws. Volume 2.
Connecticut Air Pollution Control Regulations, as amended
October 1, 1990. Section 22a-174-18. Bureau of National
Affairs.
78
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75. Environment Reporter. State Air Laws. Volume 2. Hawaii
Air Pollution Control Rules, as amended April 14, 1986.
Chapter 11-60-6. Bureau of National Affairs.
76. Environment Reporter. State Air Laws. Volume 3. Kentucky
Air Pollution Control Regulations. Title 401, Chapter KAR
61:013. Bureau of National Affairs.
77. Environment Reporter. State Air Laws. Volume 3. Maryland
Air Pollution Control Regulations, as amended April 17,
1992. Title 26. Chapter 26.11.08. Bureau of National
Affairs.
78. Telecon. Strong, B., MRI, with Torkelson, P., Minnesota
Pollution Control. December 17, 1993. Information on
existing PM and opacity limits for medical waste
incinerators in Minnesota.
79. State of Mississippi. Air Pollution Control Regulation, as
amended January 23, 1992. Section 3 paragraph 8(a) and (b).
80. State of North Dakota. Air Pollution Control Rules,
June 1992. Section 3.2.
81. State of Oklahoma. Air Pollution Control Rules,
December 31, 1991. Rules: 310:200-17-1 through 6.
82. Environment Reporter. State Air Laws. Oregon Air Pollution
Rules, October 20, 1991. Section 340-25-850. Bureau of
National Affairs.
83. State of Pennsylvania. Air Pollution Control Rules:
PA Code title 25 Section 123.12.
84. State of Rhode Island. Air Pollution Control Regulations,
June 8, 1990. Regulation 12.
85. Environment Reporter. State Air Laws. South Carolina
Ambient Air Quality Standards, June 26, 1992. Regulation
Number 62.5 Standard 3.1.
86. Environment Reporter. State Air Laws. Volume 6. South
Dakota Air Pollution Rules, as amended October 9, 1992.
Chapter 74:26:03.
87. Environment Reporter. State Air Laws. Utah Air
Regulations, March 8, 1991. Section R446-1-3.
Subsection 4.1.2.
88. State of Virginia. Air Pollution Control Board Regulations,
effective March 17, 1972. Part IV: Emission Standards for
Incinerators Rules 4-7.
79
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TECHNICAL REPORT DATA
(Please read Instructions on reverse before completing)
1. REPORT NO.
EPA-453/R-94-043a
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Medical Waste Incinerators - Background Information for
Proposed Standards and Guidelines: Process Description
Report for New and Existing Facilities
5. REPORT DATE
July 1994
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Emission Standards Division (Mail Drop 13)
Office of Air Quality Planning and Standards
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-D1-0115
12. SPONSORING AGENCY NAME AND ADDRESS
Director
Office of Air Quality Planning and Standards
Office of Air and Radiation
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/200/04
15. SUPPLEMENTARY NOTES
Published in conjunction with proposed air emission standards and guidelines for
medical waste incinerators
16. ABSTRACT
This report provides an overview of the medical waste incineration process, describes the types of
medical waste incinerators (MWI's) and their components, and discusses the combustion process as it
relates to MWI's. The report also describes current practices associated with medical waste generation,
segregation, handling, and transportation. This is one in a series of reports used as background
information in developing air emission standards and guidelines for new and existing MWI's.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Air Pollution
Pollution Control
Standards of Performance
Emission Guidelines
Medical Waste Incinerators
Air Pollution Control
Solid Waste
Medical Waste
Incineration
18. DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CLASS (Report)
Unclassified
21. NO. OF PAGES
79
20. SECURITY CLASS (Page)
Unclassified
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION IS OBSOLETE
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