EPA-230/2-86-003
United States Office of Policy, March 1985
Environmental Protection Planning and Evaluation
Agency Washington, DC 20460
Policy Planning and Evaluation
f/EPA Assessment of Incineration
As A Treatment Method for
Liquid Organic Hazardous
Wastes
Background Report I:
Description of Incineration
Technology
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DESCRIPTION OF INCINERATION TECHNOLOGY
March 1905
A background report for the study by
EPA's Office of Policy, Planning and
Evaluation: "Assessment of Incineration
As A Treatment Method For Liquid Organic
Hazardous Waste."
U.S. Environmental I'rc . ••• *.-•-
Eegion 5, Library (5F--i'o»
230 S. Dearborn Street, Room 1670
Prepared by: Chicago, IL 60604
Joe Retzer, Matthew Perl
Program Evaluation Division
Office of Management Systems and
Evaluation
U.S. Environmental Protection Agency
Washington, DC 20460
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TABLE OF CONTENTS
Page
EXECUTIVE SUMMARY i
1. INTRODUCTION ..... 1
2. INCINERATOR DESIGN FEATURES 2
2.1 Definition of Incineration 2
2.2 Basic Design Features 3
2.3 Atomizing Burner R
2.4 Combustion Chamber 10
2.5 Pollution Control Technology 12
2.6 Energy Recovery Equipment 13
3. WASTE HANDLING ASPECTS 14
3.1 Land-Based Incineration 14
3.2 Ocean Incineration 16
3.3 Key Differences In Waste Handling 17
3.4 Key Issues 18
4. PERFORMANCE CHARACTERISTICS 19
4.1 Overview of Trial Burns, Performance
Standards, and Operating Parameters .... 19
4.2 Key Parameters for Measuring Destruction ... 22
4.3 Hydrogen Chloride 30
4.4 Particulates 32
4.5 Products of Incomplete Combustion 33
4.6 Variables Affecting Combustion 34
5. SAMPLING AND MONITORING 36
5.1 Procedures for Land-Based Incinerators .... 36
5.2 Procedures for Ocean Incineration 39
5.3 Issues Regarding Ocean Burns 40
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FIGURES AND TABLES IN TEXT
2.1 Generalized Incineration System on Land .... 4
2.2 Land-Based Liquid Injection Incinerator .... 6
2.3 Rotary Kiln Incinerator with Liquid
Injection Capability 7
2.4 Vulcanus I Burner and Thermocouple Locations . . 9
2.5 Vulcanus and Apollo Combustion Chambers .... 11
3.1 Simplified Process Flow for Land-Based and
Ocean Incineration Systems 15
4.1 Test Burns of PCBs in Land-Based Incinerators .. 26
4.2 Vulcanus I Test Burns 27
4.3 Vulcanus II Test Burns 28
5.1 Trial Burn Monitoring Locations for a
Liquid Injection Incinerator 37
5.2 Issues Raised with Regard to Sampling/
Monitoring Procedures for Ocean Burns 41-42
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EXECUTIVE SUMMARY
This study provides a baseline description of both land-
based and ocean incineration technologies, identifies key
issues regarding performance capabilities and operational
techniques, and highlights the differences between the
technologies with respect to these issues. The study focuses
on the most common types of incinerators currently in use.
On land, these are liquid injection incinerators and rotary
kilns with liquid capability. For ocean incineration, the
designs reviewed are the Vulcanus I and II and the two vessels
under construction by the Tacoma Boat Company. Another ocean
design in the conceptual stage, proposed by SeaBurn Inc., is
also treated very briefly.
The information contained in the study is presented in
this summary as a series of tables. The first is a summary
table of key technological features, the second recaps the
findings of the study and the issues raised with regard to
the technologies covered, and the third discusses key
differences.
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1. INTRODUCTION
This report provides a brief description of the technical
aspects of land-based and ocean incineration in order to
identify key differences in the two technologies. The
objective is to provide a concise introduction to the design
and performance of the two technologies, and discuss issues
raised regarding their capability and reliability.
For land-based incineration, the description will focus
on liquid injection and rotary kiln incinerators. Liquid
injection incinerators are by far the most common type of
incinerator used for burning liquid hazardous waste on land,
and are the type used in the ocean incineration ships.
Rotary kilns with liquid capability are far less common, but
the major commercial competitors of ocean incineration operate
with large rotary kilns. Other, less common alternatives
for incineration of hazardous wastes are assessed in the
alternative technologies paper prepared for the OPPE
incineration study.
The description of ocean incineration will include the
two commissioned vessels, the Vulcanus I and II, as well as
the two additional ships under construction by the Tacoma
Boat Company for At-Sea Incineration. We will discuss briefly
the Seaburn Inc. and Environmental Oceanic Services proposals
for incineration at sea, since they are only at the conceptual
stage.
The assessment of incineration technology entails a com-
parison of key design features (including control technologies),
performance characteristics, operating conditions affecting
performance, waste handling features, and sampling and monitor-
ing technology. While this report identifies characteristic
emissions and waste handling techniques, it will not attempt
to assess the potential human health or environmental impacts
of the technologies, as this is done in the risk comparison
paper.
We have used a wide variety of sources in compiling this
report. Much of the information on basic design features is
widely available in basic texts as well as EPA guidance.
For specific findings on performance characteristics, we
have relied heavily on background reports prepared for the
OSW incinerator regulatory impact analysis, published reports
on the Vulcanus Test Burns, and research supporting the
development of the PCB regulations. In order to identify
issues, we reviewed the voluminous public comments on the
proposed Vulcanus permits and past regulations, and interviewed
EPA staff and incinerator operators.
-1-
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2. INCINERATOR DESIGN FEATURES
2.1 What is Incineration?
For liquid hazardous wastes, incineration is an engineered
process that uses high-temperature thermal oxidation to convert
the wastes to less hazardous materials. Incineration of simple,
nonhalogenated wastes involves the oxidation of the carbon and
hydrogen molecules present in organic wastes into carbon dioxide
and water. For example:
CH4 + 202 = CO2 + 2H2O
If conditions for complete combustion are not present, car-
bon monoxide is also formed, but this product can be minimized by
appropriate controls on temperature, turbulence and oxygen. As
a result, the presence of excessive carbon monoxide in the flue
gas is commonly used as a measure of process upset.
In general, however, the products of incineration vary with
the wastes that are burned. Many industrial processes generate
liquid hazardous wastes containing halogenated materials, with
chlorinated compounds being the most common. When chlorinated
organic compounds are combusted, the products will include hydro-
gen chloride and small amounts of chlorine, as well as carbon
dioxide and water. Other liquid hazardous wastes may contain
metals, sulfur, or organically bound nitrogen and produce, when
incinerated, oxides of metals, sulfur, and nitrogen.
In addition, all combustion sources, including hazardous
waste incineration, will form small amounts of substances other
than water, HC1 and the simple oxides that are the expected
products of the combustion reaction. These substances, known
collectively as products of incomplete combustion (PICs) may
be similar to or very different in chemical structure from the
original constituents of the compounds incinerated. Little is
known about how these substances are formed, or which substances
are formed from the burning of specific wastes. The PICs which
have received the most attention are the dioxin and dibenzofuran
compounds because of their high toxicity to human health and
the environment.
An important consideration for hazardous waste incineration
is the heating value of the wastes. To maintain stable combus-
tion, the heat released by combustion must also heat incoming
waste to its ignition temperature and provide the activation
energy for oxidation reactions to occur. The heating value of
a waste normally decreases as the percentage of water increases
and as the percentage of chlorine by weight in organic compounds
increases. Liquid wastes with low heating values may require
auxiliary fuel or blending with wastes that have higher Btu/lb
values. As a practical matter, commercial incinerator operators
dealing with wastes from a variety of sources will blend wastes
to produce optimum values for Btu, chlorine, water, and other
contents.
-2-
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2.2 Basic Incineration Design Features
All waste incinerators on land consist of a waste feed
system, a combustion air or oxygen system, a combustion
chamber, combustion monitoring systems, and, if required,
an air pollution control system and an ash removal system.
The simple flow schematic in Figure 2.1 illustrates the
relationships of these basic elements of incinerator design.
These elements are applied somewhat differently in liquid
injection and rotary kiln systems.
2.2.1 Liquid Injection Systems on Land
Capable of incinerating a wide range of liquids, gases
and slurries, the liquid injection system is the most frequently
used hazardous waste incineration system in the United States.
The combustion system in a liquid injection incinerator has
a very simple design with virtually no moving parts. A burner
or nozzle atomizes the liquid waste and injects it into the
combustion chamber where it volatilizes and is incinerated.
A forced draft system supplies the combustion chamber with
air to provide oxygen for combustion and turbulence for
mixing. The combustion chamber is usually a cylinder lined
with refractory brick, and may be fired horizontally (as
illustrated in Figure 2.2), vertically upward, or vertically
downward. The specific configurations are designed to satisfy
the needs of the owner.
2.2.2 Rotary Kiln Systems on Land
Rotary kiln systems are capable of incinerating solid,
sludge, liquid, and gaseous hazardous wastes either separately
or simultaneously. Solid wastes are usually combusted with
fuel or high-Btu liquid wastes in order to maintain high
temperatures and aid in combustion of low heat content solids.
Because of their versatility, rotary kilns have been used
for large commercial facilities in the United States and
regional hazardous waste management facilities in Europe.
A rotary kiln is a slowly rotating, refractory-lined
cylinder that is mounted at a slight incline from the hori-
zontal (Figure 2.3). Solid wastes enter at the high end of
the kiln, and liquid or gaseous wastes enter through atomizing
nozzles. Rotation of the kiln exposes the solids to the
heat, vaporizes them, and allows them to combust by mixing
with air. The rotation then causes the ash to move to the
lower end of the kiln where it can be removed. Rotary kiln
systems usually have a secondary combustion chamber or after-
burner following the kiln to ensure more complete combustion
of the wastes. The secondary chamber may also be fired with
fuel or liquid wastes. Although rotary kilns have the advantage
of incinerating liquids and solids independently or in
combination, they also have relatively high capital costs
compared to liquid injection systems.
-3-
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Figure 2.1 - Generalized Incineration System on Land
Exhaust Gas
Monitors
Air
Waste >
Auxiliary
Fuel >
Combustion
Chamber
Air Pollution
Control
— ->
> Treated Exhaust Gas
v
Ash
Removal
> Solid Discharge
(If dry process used
for particulates)
Water
Treatment
v
Treated
Discharge
Water
Wastewater
Treatment
Sludge
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2.2.3 Ocean Incineration
The Vulcanus ships employ vertically mounted liquid
injection incinerators, each having three rotary cup vortex
burners, firing into a cylindrical, refractory-lined combus-
tion chamber. The Vulcanus I has two incinerators mounted
on its stern, and the Vulcanus II has three incinerators.
All five incinerators were designed and constructed by the
same firm (H. Saacke KG) and are very similar in size and
shape, although the incinerators on the Vulcanus II are
slightly larger than those on the Vulcanus I (151 cubic
meter volume versus 130 cubic meters). Each incinerator is
capable of burning approximately 7 1/2 tonnes/hr. (1650 gal-
lons) of liquid waste. The Vulcanus I has a cargo capacity
of approximately 800,000 gallons (3500 tonnes), and the
Vulcanus II a capacity of approximately 724,000 gallons
(3200 tonnes).
Two additional incinerator ships are under construction
by the Tacoma Boatbuilding Company for At-Sea Incineration
(also known as the Apollo ships). At-Sea Incineration has
applied to EPA for a permit for the first of these vessels.
Each will be equipped with two vertically mounted liquid
injection incinerators in the stern. The cargo capacity of
each ship will be somewhat larger than the Vulcanus ships
(1.3 million gallons or 6,000 tonnes) and each will be able
to burn about 25 tonnes/hr (5500 gallons) of liquid hazardous
waste (12 1/2 tonnes/hour per incinerator).
An ocean incineration plan proposed by SeaBurn Inc. would
make use of an oceangoing barge, towed by a tug, and carrying
144 mobile stainless steel tank containers located above the
main deck in vertical cells. This would provide a total capa-
city of approximately 720,000 gallons. This operation would
permit standard containers to be loaded with waste at the
generator's site, transported by trailer or rail, and lifted
on board by container cranes. Incineration would be provided
by two horizontally mounted liquid injection incinerators
equipped with seawater scrubbers to cool and dilute the exhaust
plume and quicken the mixing of acidic and particulate emissions
with the sea. Environmental Oceanic Services has also proposed
an ocean incineration plan using stainless steel containers to
collect and transport wastes. They propose using a smaller,
self-propelled supply vessel, modified to carry an incinerator
and containers of hazardous wastes.
in general, the waste burning rate for ocean incineration
is greater than that for most land-based systems. For example,
each incinerator on the Vulcanus burns about 1650 gallons of
waste an hour. In contrast, the median capacity for land-based
liquid waste incinerators is 150 gallons per hour. In an
offshore 1982 EPA survey, only 8 land-based incinerators
reported a capacity greater than 2000 gallons an hour.
-5-
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Figure 2.2
LAND-BASED
LIQUID INJECTION INCINERATOR
LIQUID WASTE
STORAGE
WASTE
CONDITIONING
SUPPORT FUEL •
IF REQUIRED
ATOMIZING GAS -
COMBUSTION
AIR
FUMES
DISPERSION STACK
SCRUBBED
GASES
"*[ HX. COMBUSTION CHAMBER
.-^JT \
4i A
VENTURISCRUBBER
MAKEUP WATER /^^^
WATER TREATMENT I r
RESIDUE
-------
— n*i
•H
rH
•H
O
•iJ
US
M
n
I
O
4J
s
-------
2.3 The Atomizing Burner
2.3.1 Land-based Incineration
One of the major design factors affecting the performance
of a liquid hazardous waste incinerator is the operation of
the waste burner. The functions of a properly designed and
operated burner are to atomize the fuel and waste, position
the flame, maintain continuous ignition, and help ensure the
correct supply and proportions of fuel and air. Good atomiza-
tion is particularly important to ensure complete burning
and prevent the escape of unburned droplets of waste.
A variety of atomizer nozzle designs have been employed
in incinerator burners, and the designs are usually classified
by the source of atomizing energy: whether the flowing waste
itself, a second fluid such as air or steam, or an external
mechanical device, such as rotating cups. Although some
experimental information is available on burner operating
characteristics, sufficient data does not exist to correlate
liquid injection hazardous waste burner performance with the
destruction and removal performance achieved by the incinerator
system. The diversity of burner operating characteristics,
combustion chamber geometries, and other incinerator operating
conditions has led EPA to focus on the existing destruction
and removal efficiency performance standard rather than a
design standard for burners.
2.3.2 Ocean Incineration
Each Vulcanus incinerator provides atomization and flame
control with three rotary cup burners located about 3 meters
from the base (Figure 2.4). The rotary cup consists of an
open cup mounted on a hollow shaft, which is spun rapidly
(6000 rpm) as the liquid waste is delivered through the
shaft. Rotational velocity spreads the liquid into a thin
sheet as it forces the liquid to the rim of the cup where it
is torn from the rim as a thin film. Surface tension causes
the film to break into tiny droplets while high velocity air
provides thorough mixing of the droplets with combustion air
and shapes the flame. Combustion air is provided by one large
fixed-speed fan for each incinerator, with a metered air flow
rate controlled by an adjustable damper.
2.3.3 Issues
Maintaining atomizing burners in good operating condition
is an issue for both land and ocean incinerators. In normal
operation, atomizing burners in liquid injection incinerators
are subject to corrosion and plugging which may impede atomiza-
tion, change the spray angle, or produce uneven flow rates.
The best protection against these mishaps is (1) selection
of a design appropriate to the specific incinerator geometry
and waste characteristics, and (2) frequent visual inspection,
monitoring of feed pressure, and cleaning and replacement
when necessary
-------
Figure 2.4 Vulcanus I Burner and Thermocouple Locations
BURNER 6
BURNER 5
THERMOCOUPLE INDICATORS
(BLACK-BOX AND CONTROL PANEL)
(STARBOARD FURNACE)
THERMOCOUPLE FOR STARBOARD
FURNACE AUTOMATIC SHUT-OFF
BURNER 4
BURNER 3
BURNER 1
THERMOCOUPLE FOR PORT
FURNACE AUTOMATIC SHUT-OFF
THERMOCOUPLE INDICATORS
(BLACK BOX AND CONTROL PANEL)
(PORT FURNACE)
BURNER 2
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Some commenters have criticized the design of the rotary
cup burners used on the Vulcanus ship, questioning the ability
of the burners to provide adequate atomization, especially on
a moving ship. They also contend that the design has been widely
discontinued and is not the best technology available.
In fact, most of the land-based incinerators in the United
States that EPA has studied do not use the European-style rotary
cup atomizers, but have adopted pressure spray nozzles using air
or steam to assist atomization. However, burner designs are
extremely variable, and EPA has measured acceptable incinerator
performance for a wide range of burner designs, including the
rotary cup burner observed throughout the Vulcanus monitoring
activities. Therefore, EPA has focused regulation on incinerator
performance rather than burner design.
2.4 The Combustion Chamber
2.4.1 Land-based Incineration
in land-based incinerators, combustion takes place in a
refractory-lined chamber that is designed to promote mixing of
the waste and air and to allow sufficient residence time for
the reactants to complete combustion. In some syste'ms where
liquid and solid wastes are incinerated, a secondary combustion
chamber or afterburner is used to assist the combustion process.
2.4.2 Ocean Incineration
The combustion chambers for the Vulcanus ships are large
vertically fired cylinders with a brief converging section which
connects directly to the exit stack. The dimensions of the
chamber are indicated in Figure 2.5. Burners are oriented
tangentially to the vertical sides of the incinerators to pro-
vide swirling and mixing of combustion gases. Ocean incinerator
design does not include an afterburner because only liquid
wastes are incinerated.
The Apollo incinerators are similar in size and shape to
those on the Vulcanus. Although the overall heights and diame-
meters are approximately the same, the Apollo has a shorter
stack and taller combustion chamber.
2.4.3 Issues
A few critics of the Vulcanus have argued that the incine-
ration chamber design is inadequate because it does not provide
sufficient turbulence for mixing of the waste with oxygen or
enough residence time for complete combustion. The Office
of Water believes that the appropriate test of the incinerator
system is its performance characteristics rather than the
design features. Although chamber design effects performance,
no clear formula exists for linking chamber design to destruction
efficiency.
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Figure 2.5 Vulcanus and Apollo Ccnbustion Chambers
4.6 M
3.4M.
1.0.
l.<
10.45 M
3.5 M
0.75 M
\
4.8 M
1.0.
Vulcanus
) STACK
COMBUSTION
CHAMBER
t
in
3.!
C. M
5 M
/
7.1 M
4.3 M
I.D."
STACK
COMBUSTION
CHAMBER
Apollo
11
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The RCRA program also focuses on performance rather than
chamber design. Most currently used land-based incinerators
have been designed based upon estimation, engineering judgments,
individual preferences, and trial and error procedures. EPA
has evaluated a wide range of designs and has found that most
of them will perform satisfactorily with proper operating
temperatures, feed rates, and maintenance.
2.5 Pollution Control Technology
2.5.1 Land-based Incineration
Regulations for incinerators under RCRA and TSCA require
controls on air emissions, scrubber water disposal, and ash
disposal. Therefore, land-based hazardous waste incinerators
include air pollution control devices for acid gases and
particulates, as well as systems for treating or disposing
of scrubber water and any ash residues. The installation of
specific control technology depends, of course, on the type
of incinerator used, the properties of the waste being incine-
rated, and the regulations applicable to the incinerator's
location. Generally, however, air pollution control equipment
will contain most, if not all, of the following components:
o Quench chamber or heat exchanger to cool the flue
gas in order for downstream air pollution controls
to operate more effectively.
o Device to collect particulates, such as venturi
scrubber, baghouse, electrostatic precipitator,
cyclone, or ionizing wet scrubber.
o Device to remove gaseous pollutants such as packed
tower, plate, or spray tower scrubbers.
o A mist eliminator to separate water droplets from the
flue gas.
o Flue gas handling equipment including ducts, dampers,
blowers, and a stack.
2.5.2 Ocean Incineration
EPA does not require air pollution control equipment on
ocean incinerators. Neither the Vulcanus nor the Apollo
ships use air pollution control equipment, so there is no
need to treat or dispose of scrubber water. The proposed
SeaBurn vessel would be equipped with seawater scrubbers,
but only to dilute the plume and cause it to descend to the
sea more rapidly.
-12-
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2.5.3 Issue
The primary issue for both land-based and ocean incine-
ration is the impact on human health and the environment of
emissions of HC1 and particulates. For land, the question
is whether current controls are adequately protective; for
the ocean, it is whether the absence of control technology
results in undue risk to the environment. We will defer dis-
cussion on this issue until section 4, which includes a full
description of performance characteristics and emissions.
An additional issue for land-based incineration is the
handling of scrubber water or solid material captured in the
air pollution system. Under RCRA regulations, these products
of incineration must be treated or disposed of as hazardous
waste.
2.6 Energy Recovery Equipment
2.6.1 Land-based Incineration
In recent years there has been increasing interest in
recovering the heat generated by the incineration of hazardous
wastes. According to a 1982 EPA study, about one-fourth of
the incinerators burning liquid hazardous waste employed heat
recovery. Incinerator vendors reported, however, that about
ninety percent of recent price quotations requested by pro-
spective customers specified energy recovery equipment.
Energy is most often recovered as steam, which may be
used for electricity generation, driving machinery, heating,
or to raise the temperature of incoming combustion air. Steam
generation usually involves boilers using firetubes (flue gases
flowing through tubes heat surrounding water) or water tubes
(water flowing through tubes is heated by surrounding hot flue
gases). A major limiting factor in the use of heat recovery
is the strong corrosive impact of hydrogen chloride which
results from the combustion of chlorinated wastes.
2.6.2 Ocean Incineration
The Vulcanus and Apollo ships and the SeaBurn proposal
do not include mechanisms for heat recovery because the energy
that would be generated could not be utilized at-sea and
because the high concentration of HCl in ocean incinerator
emissions could damage heat recovery equipment.
2.6.3 Issue
Because the Vulcanus does not involve heat recovery, a
concern was raised about the potential loss of energy from
ocean incineration. EPA has not required heat recovery on
land-based or ocean incineration because it does not directly
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affect human health and the environment, and because incinerator
operators will, in their own economic interest, choose to
recover heat when it is technically and economically feasible.
3. WASTE HANDLING ASPECTS
This section provides an overview of the steps involved
in the waste handling aspects of incineration from the point
at which wastes are transferred to the incinerator operator
to the point of final disposal of residual wastes resulting
from the incineration process. Issues raised concerning these
aspects are also covered. This section does not examine the
potential risks associated with waste transport pathways, as
these are covered in the comparative risk assessment paper.
3.1 Waste Handling Aspects of Land-Based Incineration
Figure 3.1 illustrates a typical process flow for a land-
based commercial incinerator. In practice, many variations
occur, especially among on-site and smaller facilities. In
this illustration, incoming wastes are delivered to the facility
either as liquids in tank trucks or in drums and other types
of containers. Currently, most land-based facilities utilize
truck fleets to transport wastes, but some facilities also
rely on transport by rail and barge. If the wastes have not
been previously identified, they are tested to determine
content, viscosity, and combustion value. Then the wastes
are pumped into temporary storage tanks which are set up to
accommodate compatible waste streams.
Some incinerator operations may utilize a blending tank
to prepare an optimal mixture for burning. Other facilities
simply pump wastes from different storage tanks directly to
the incinerator, thus mixing the wastes during the actual
burning. When incineration begins, wastes are pumped from
the storage tanks or the blending tank to the incinerator at
feed rates which provide for optimum combustion and which do
not exceed the maximum thermal input (Btu per hour) allowed
by the permit. If necessary, supplementary fuel may be fed
into the incinerator to enhance combustion.
Following incineration, scrubbers are employed to remove
acid gases and particulates before they can be released from
the stacks. This process creates scrubber water which is
classified as a hazardous waste. One option for managing
the scrubber water is to channel it into a settling pond for
removal of the sludge and to recirculate the water for subse-
quent use in the scrubbers. The remaining sludge is then
disposed of in a hazardous waste landfill on or off site.
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Figure 3.1 Simplified Process Flow for a Land-Based Incinerator
and an Existing Infrastructure Ocean Incineration
System
Incoming
Liquid
Waste in
Drums and
Containers
Incoming
Liquid Waste
in
Tankers
DeDru mining
Facility
Waste
Decontamination Rinsate
Metal
Scrap
Temporary
Storage Tanks
Blending Tank
(Optional)
Land-Based
Incineration
Residuals and
Scrubber Water
Management of
Residuals and f-f
Scrubber water
_On-site or
Off-site
Wastewater
"Treatment Plant
Hazardous Waste
'Landfill
Underground
Injection Well
(LAND-BASED INCINERATION)
Truck or Rail
Transport
Ooc
:ksi
side
Loading Area
Inci nerator
Vessel Travels
To Burn Site
Ocean
Incineration
Residuals In-
cinerated at
Sea or Disposed
of on Land
(OCEAN INCINERATION)
15
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Another option simply involves disposing of all scrubber
water in underground injection wells. A third option is to
treat scrubber water in a National Pollutant Discharge Elimi-
nation System permitted unit. After treatment, the effluent
water is no longer considered to be hazardous and may be
discharged into sewers or waterways, subject to NPDES permit
limitations. The sludge, however, is still considered
hazardous, and must be disposed of accordingly.
3.2 Waste Handling Aspects of Ocean Incineration
Three categories of logistical systems have been described
as options for managing waste handling aspects of ocean
incineration. These are no-infrastructure, integrated, and
existing infrastructure systems.
o No-Infrastructure Systems: This system minimizes the
use of fixed facilities. Wastes accumulate at their
sources and are stored in truck or rail tanks or
portable liquid containers. Filled containers are
transported to an existing port transfer facility
which is not dedicated solely to incinerator ship
operations. The wastes are then pumped or the con-
tainers lifted directly onto vessels. There is no
blending of wastes from different sources prior to
loading aboard ships although different waste streams
may be segregated on board. During actual incineration,
wastes are fed to the burners from different storage
tanks to provide the best burning mixture.
Variations of the no-infrastructure system have been
proposed by Seaburn Inc. and Environmental Oceanic
Services. They call for the use of stainless steel
tank containers to be collected at generator sites
and shipped to port. The sealed containers themselves
are loaded on an incinerator vessel. Since each
container has a direct feed to the incinerator, the
wastes never leave the container until actual incinera-
tion of the wastes begins at sea.
o Existing Infrastructure Systems: An existing infra-
structure system is similar to a no-infrastructure
system in that it makes use of port transfer facilities
which are not dedicated solely to incinerator ship
operations. It differs from the no-infrastructure
system primarily in that it allows for blending,
"preparation, and storage functions to be performed
at existing, centralized facilities which are separate
from the port facility.
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Chemical Waste Management Inc. (CWM) proposed to
employ an existing infrastructure system to support
its Vulcanus incinerator vessels. Liquid wastes
would be transported from generators to CWM's testing,
storage, and blending facility at Emelle, Alabama.
Blended waste streams would be truck transported to
an existing port facility at Chickasaw, near the port
of Mobile, Alabama, and wastes would be pumped directly
onto the Vulcanus. Figure 3.1 illustrates a process
flow for ocean incineration using an existing infra-
structure system.
EPA's proposed permits for the Vulcanus ships required
that, following incineration of the wastes at the
designated burnsite, any ash resulting from the
process, solvents used to wash tanks, contaminated
shipboard waters, or other hazardous materials must
be incinerated at sea, or upon return to port disposed
of in accordance with EPA regulations.
o Integrated Systems: An integrated system involves the
siting of a specialized port facility dedicated pri-
marily to incinerator ship operations. The facility
receives waste from generators and has the capacity
for analyzing, blending, and storing them. Additionally,
the facility is equipped to handle both containers and
tanked liquids, and incorporates safety features to
prevent leakage of wastes to the surrounding environ-
environment. Variations on this concept have been
proposed in the past by the Interagency Ad Hoc Work
Group for the Chemical Waste Incinerator Ship Program
and by At-Sea Incineration, Inc.
3.3 Key Differences in Waste Handling
As indicated in Figure 3.1, a typical process flow for
land-based and ocean incineration may involve the same steps
up through the waste blending operation. Following blending,
the key difference between the two forms of incineration is
primarily in subsequent transport of the wastes and disposal
of residuals.
On land, the wastes are pumped directly from the blending
tanks or temporary storage tanks to the incinerator. In con-
trast, an existing ocean infrastructure system/ such as that
proposed for the Vulcanus, would require an additional transfer
and transport leg to haul wastes from the blending site to the
port site (CWM's Chickasaw port transfer site is approximately
140 miles from its Emelle blending and storage facility).
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The other key handling differences are in the disposal
of residuals. Land-based facilities must handle scrubber
water resulting from their processes. Current ocean inciner-
ation operations are not faced with managing scrubber water,
since they do not use scrubbers. Even under the proposed
SeaBurn system, there is still no scrubber water residual,
since seawater used in the guench system would be returned
directly to the ocean.
3.4 Key Waste Handling Issues
Critics are concerned that the mixing of incompatible
wastes could lead to runaway chemical reactions, fires or
explosions and therefore poses potential problems for both
land and ocean incinerators. However, tests for waste
compatibility are a routine part of system safeguards for
commercial incinerator operations.
For ocean incineration, CWM routinely tests incoming
wastes for blending compatibility at its facility in Emelle,
Alabama. Only after the wastes are found to be compatible
are they blended. CWM reports that blended wastes are- held
in storage tanks for a minimum of several days before loading
into tank trucks for transport to the Vulcanus. Any reaction
that could occur would occur by this time. No further
blending of wastes is done once the wastes are removed from
the storage tanks at Emelle. However, batches of blended
waste from Emelle could be loaded into the same tank on the
vessel.
For land-based incinerators, permits indicate the scope
and frequency of sampling of incoming waste to determine
whether it is within permit-specified physical and chemical
composition limits, and in order to prevent the mixing of
incompatible wastes. In general, it is in the best interest
of land and ocean incinerator operators to ensure that adequate
testing of incoming waste is done as a safeguard to protect
their own investments and the safety of their employees.
However, because of the many variations in waste handling
practices on land, waste incompatibility could be a potential
problem if normal safeguards are not consistently applied.
An additional concern involves the potential for spills
and fugitive emissions during the collection, transport,
pumping, and storage of the wastes. In the absence of concrete
data, the SAB and others have speculated that releases from
handling and storage might be large. The risk assessment
conducted for this study, however, indicates that such releases
are probably very small compared to stack emissions.
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Neither the MPRSA nor the Ocean Dumping Regulations speci-
fically addresses the issue of siting of transfer and loading
facilities. However, the transfer facilities are subject to
comprehensive control under U.S. Coast Guard regulations, which
address conditions which must be met for the designation of a
waterfront facility for handling and loading hazardous sub-
stances (33 CFR Part 6, 125, 126). EPA's proposed regulations
reguire incineration companies to develop a contingency plan
which outlines safety precautions to prevent accidents during
loading and provides a workable plan for responding to any
accidents that may occur.
4. PERFORMANCE CHARACTERISTICS
4.1 Overview of Trail Burns, Performance Standards, and
Operating Parameters
This section outlines regulatory reguirements and per-
mitting procedures to place in context the subseguent technical
discussion of performance characteristics.
4.1.1 Land-Based Incineration: Trial Burns and Performance
Standards
In order to obtain a RCRA permit for operating a hazardous
waste incinerator, the applicant must demonstrate the
incinerator's ability to comply with EPA performance standards.
Compliance with the standards for incineration of hazardous
wastes (40 CFR 264.340 through 264.351) is generally
established through conducting a trial burn. Initially, waste
streams most likely to be treated at the facility are selected
for the trial burn and analyzed for:
o Heating value of the waste;
o Viscosity;
o Concentrations of hazardous constituents listed in 40
CFR 261, Appendix VIII, expected to be present in the
waste;
o Organically bound chlorine content (established during
trial burn and listed in the permit);
o Ash content (established during trial burn and listed
in the permit).
During the trial burn, the incinerator must achieve the
following performance levels:
o Destruction and removal efficiency (ORE)- 99.99% for
Principal Organic Hazardous Constituents (POHCs);
-19-
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o Hydrogen chloride (HC1) emission - 99% removal or
less than 1.8 kilograms per hour;
o Particulates- 0.08 grain per dry standard cubic foot
(dscf) when corrected for amount of oxygen in the
stack.
If the incinerator operator plans to burn PCBs, he must
receive a separate approval from the Assistant Administrator
of the Office of Pesticides and Toxic Substances in order to com-
ply with TSCA. For liguid PCBs, regulations generally require:
o A combustion efficiency of 99.9%, and
o Either of the following operating conditions:
1200°C + 100, 2-second residence time, and 3%
excess oxygen, or
1600°C +; 100, 1.5-second residence time, and 2%
excess oxygen.
However, EPA will allow other than specified temperature
and residence times if equivalent DRE can be demonstrated.
4.1.2 Land-based Incineration: Operating Parameters
Once the trial burn has been conducted on the selected
waste streams and adequate performance demonstrated, routine
operations can begin. The final permit designates a set of
operating requirements based upon the results of the trial
burn which are specific to each waste feed burned and reflect
the range of operating conditions shown to achieve acceptable
performance levels. Operating requirements are specified in
the permit for the following parameters:
o Carbon monoxide (CO) level in the exhaust stack
gas (indicator of combustion upset and combustion
efficiency)
o Waste feed rate
o Combustion zone temperature (although the exact
location of the temperature sensor will vary in each
case, a location should be specified in the permit
which insures that temperature is always monitored
at the same point during routine operation)
o Combustion gas flow rate (indicates residence time
in combustion zone)
o Air pollution control device operating conditions.
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4.1.3 Ocean Incineration: Performance Standards, Trial
Burns, and Operating Requirements
EPA is proposing a trial burn procedure similar to that
used under RCRA in permitting land-based incinerators to
ensure that ocean incinerator vessels can achieve acceptable
destruction efficiencies. This method calls for the applicant
to submit a trial burn plan to EPA for approval as part of
its overall application for an Operating Permit.
During the Trial Burn the incinerator vessel must do
three things:
o Demostrate that a Destruction Efficiency (DE) of at
least 99.99% on POHCs, a DE of at least 99.9999%
on PCBs chosen as POHCs, and a Combustion Efficiency
(CE) in excess of 99.9% is achieved.
o Define or gualify the range of wastes that can be
burned by the system to achieve 99.99% DE and 99.9%
CE.
o Determine the optimum operating conditions under
which acceptable DE and CE can be met.
Additionally, the trial burns may also be used to test
the DE and CE of the system on the five wastes specified by
the London Dumping Convention (LDC) for which doubts exist
as to the thermal destructability and efficiency of destruction.
These wastes are: polychlorinated biphenyls (PCBs), pol-
ychlorinated terphenyls (PCTs), tetrachlorodibenzo-D-dioxin
(TCDD), benzene hexachloride (BHC), and dichlorodiphenyl
trichloroethane (DDT). If the incinerator will be burning
any of these wastes, they must be tested in the trial burn.
To summarize, trial burns are conducted orimarily to
demonstrate the destruction efficiency and combustion efficiency
of the system on POHCs, and to establish operating conditions
under which the DE can be met for a range of wastes.
After EPA determines that the trial burn adeguately
demonstrates the ability of the incinerator vessel to
comply with the performance standards at a determined set of
key operating parameters, operations could begin. Operating
conditions under the Operating Permit are oriented towards
ensuring that the CE performance standard is achieved which
indicates acceptable DE. Continuous monitoring and recording
would be required for the following operational parameters:
o Wall temperature;
o Oxygen concentration in combustion gases;
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o Carbon dioxide and carbon monoxide concentrations
in combustion gases;
o Waste flow rates and/or auxiliary fuel (if used)
feed rates to the incinerator;
o Status of the flame;
o Air flow to the incinerators; and
o Amount of wastes incinerated.
In addition, operating requirements are specified for
the three key parameters of incinerator wall temperature,
and carbon monoxide and oxygen concentration in the stack
gases.
4.2 Key Parameters for Measuring Destruction of Hazardous
Constituents
4.2.1 Destruction Efficiency and Destruction and Removal
Efficiency
Performance of hazardous waste incinerators is normally
measured in terms of destruction efficiency (DE) or destruction
and removal efficiency (DRE). Destruction efficiency refers
to the percentage of hazardous constituents destroyed in the
combustion chamber, while destruction and removal efficiency
accounts for both the destruction in the combustion chamber
and removal of remaining original hazardous constituents by
air pollution control equipment. The RCRA regulations require
a DRE for principal organic hazardous constituents (POHCs)
of 99.99%, based on the following formula:
DRE = (Win - Wnnt.) x 100
Win
Where: Win = mass feed rate of a constituent in the waste
stream feeding the incinerator.
Wout = mass emission rate of the same constituent in the
exhaust emissions prior to release to the atmosphere.
4.2.2 Combustion Efficiency
Combustion efficiency (CE), another indicator used to
measure incinerator performance, is an indirect measure
of an incinerator's ability to achieve a high level of waste
destruction. It measures the extent to which carbon in the
waste is oxidized to form CC>2 rather than CO, an indication
of complete rather than partial combustion. Combustion
efficiency is defined as:
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x 100
Where:
CE = combustion efficiency
CC02 = concentration of C02 in exhaust gas
Cco = concentration of CO in exhaust gas
RCRA regulations do not require measurement of CE,
although permits specify maximum CO levels in the stack gas
on a case by case basis. PCB regulations continue to specify
a 99.9 percent CE, which the Office of Toxic Substances
believes to be an indicator of a DRE of 99.9999 percent.
EPA requires 99.9% CE for ocean incineration.
There is still some uncertainty within EPA as to whether
a precise relationship can be determined between CE and DE
or DRE in incinerators, other than the usual finding of good
DE or DRE with good CE. The Office of Research and Develop-
ment's (ORD) current thermal destruction program is conducting
research at the lab/pilot scale to better understand these
relationships.
4.2.3 Principal Organic Hazardous Constituents
Because many of the liquid hazardous wastes to be incine-
rated are complex mixtures of many different compounds, the
RCRA program developed a system whereby the overall performance
of an incinerator is measured by tests on a small number of
waste constituents or individual hazardous compounds. The
Office of Water has also adopted this approach for the ocean
incineration program.
The testing system uses a small number of principal
organic hazardous constituents (POHCs) to represent the many
compounds found in a complex waste. In order to use POHC
surrogates to represent many compounds, EPA developed a
system to rank compounds on the basis of how difficult they
are to burn. Incinerability is measured by "heat of combus-
tion," a theoretical calculation of energy released when
waste molecules are combusted. Compounds with a lower heat
of combustion are presumed to be more difficult to burn than
those with a higher heat of combustion.
Using the incinerability ranking, the test designer
selects a few compounds, the POHCs, on which to measure
destruction efficiency. Generally, constituents which are
most difficult to destroy and most abundant in the waste
mixture are selected. When a trial burn demonstrates that
an incinerator can achieve a destruction efficiency of 99.99
percent for a particular POHC, the constituents with higher
heats of combustion (less difficult to burn) burned in that
incinerator under comparable conditions are also presumed
to be destroyed.
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4.2.4 Performance of Land-Based Incinerators
During the 1970's, EPA conducted or identified 54 test
burns of hazardous wastes in which destruction efficiency
was measured. The tests involved not only liquid injection
and rotary kiln incinerators, but also hearth incinerators
and newer technologies such as molten salt, fluidi7ed bed,
and pyrolysis. All but nine of the tests achieved a destruc-
tion efficiency of at least 99.99 percent, and many of the
lower destruction efficiencies could be traced to extreme
test conditions or identifiable and correctable problems.
These test burns became the basis for the selection of the
99.99 percent DRE standard in the RCRA regulations.
In order to develop further information on incinerator
performance in conjunction with an incinerator Regulatory
Impact Analysis (RIA), EPA conducted case studies of 51
incinerators at 34 sites. Test burns were performed at 8 of
the facilities. All eight incinerators with test burns had
liquid injection devices, but some also had rotary kilns to
burn solids. The tests involved a wide variety of incinerator
designs, control devices, waste types, and operating conditions,
In general, the test burn results provide additional sup-
port for the capability of achieving DREs of 99.99 percent.
Of 240 DREs calculated (for each test run for each compound),
nearly two thirds were greater than 99.99 percent. Of the
remainder, seventy percent were above 99.9 percent. Most of
the cases below 99.99 percent DRE occurred when (1) there
was a very low concentration of the POHC in the waste feed,
or (2) when the compound was one which had been identified
as a product of incomplete combustion at other facilities.
ORD reported that the tests were done while the incine-
rators were performing at their best, with close and careful
maintenance and attention. Poor visual stack emissions were
observed on occasion with careless or inept operators, and
while these emissions were not measured or quantified, ORD
felt that the emissions would have been unacceptable under
RCRA. Overall, ORD reported that the tests reinforced
their appreciation for quality of operations and its impact
on performance.
4.2.5 Destruction of PCBs on Land
Data from many test burns of polychlorinated biphenyls
(PCBs) provide evidence that the thermal destruction of PCBs
in incinerators, in accordance with PCB regulations, can be
accomplished with high efficiency and minimal emissions of
undestroyed PCBs. The information in Table 4.1 shows data
from PCB test burns in six incinerators of varying design
and operating conditions. All but one burn achieved at
least 99.9999 percent DRE, with the lowest value reported
as 99.9971 percent.
- 24 -
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4.2.6 Performance of the Vulcanus
EPA's conclusions regarding the performance capabilities
of the Vulcanus ships are based on evaluations of data recorded
during a number of test burns. Tables 4.2 and 4.3 summarize
information on the test burns where destruction efficiencies
were reported.
The Background Document on the Tentative Determination
to Issue Permits made use of only three of these burns in
considering the capability of the Vulcanus ships and proposing
limits on wastes to be burned for the proposed special permits.
(See tables).
o The July-September 1977 burn of Agent Orange by the
Vulcanus I in the Pacific is cited as evidence of at
least 99.99 percent destruction efficiency of three
compounds, including dioxin (TCDD). The actual
calculated DE for dioxin of greater than 99.93
percent was judged to be a low estimate because:
(1) chemicals with a lower heat of combustion achieved
DEs greater than 99.99 percent, and (2) low concen-
trations of dioxins in the waste mixture challenged
the capabilities of the analytical methodology.
o The August 1982 Vulcanus I burn of a PCB mixture
showed DEs greater than 99.99 percent for several
POHCs, and greater than 99.999 percent for PCBs.
The POHC with the lowest heat of combustion was
hexachlorobenzene (1.79 Kcal/gram), and this was
chosen as the limiting waste for the Vulcanus I
permit.
o The February 1983 Vulcanus II burn showed DEs greater
than 99.99 percent for a variety of liguid organo-
chlorines. The POHC with the lowest heat of combustion
was tetrachloromethane (carbon tetrachloride, 0.24
Kcal/gram), and this was chosen as the limiting
waste for the Vulcanus II permit.
o Although the Vulcanus II did not have a test burn
with TCDD or PCBs, EPA tentatively concluded that
the Vulcanus II is capable of adeguately incinerating
these wastes based on the Vulcanus I tests, and the
similarity of the Vulcanus II incinerators to those
of its sister ship.
In the tentative determination on the special permits,
EPA treated the August 1982 burn (Vulcanus I) and the February
1983 burn (Vulcanus II) as the definitive trial burns for
determining compliance with the DE reguirement, and establishing
waste limitations and operating reguirements. The Agent
Orange burn of 1977 was also cited as specific evidence in
support of sufficient incineration of dioxins.
- 25 -
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4.2.7 Issues
A large number of individuals and groups challenged EPA' s
findings regarding the performance capabilities of the Vulcanus
incinerators. Many of the concerns focus on the sampling
practices and analytical methodologies used in the test
burns. These concerns and the recommendations contained in
the proposed regulations for dealing with them are summarized
later in this paper in the section on sampling and monitoring.
Five additional issues related to performance are discussed
here.
o Destruction Efficiency for PCBs
Although the Vulcanus I demonstrated a destruction effi-
ciency of greater than 99.999 percent for PCBs and met the
TSCA requirements for liguid PCBs, it did not meet the 99.9999
percent DE which EPA has required for burning liquid PCBs on
land as a matter of permitting practice.
Based on operating requirements and measures of combustion
efficiency, EPA scientists believe that the Vulcanus routinely
achieves the "six nines" level of destruction. The problem
is that insufficient volumes of the combustion gases were
sampled on the Vulcanus to demonstrate conclusively DEs of
99.9999 percent during previous burns. For this reason, EPA
anticipates that required testing during future trial burns
will collect a larger sample volume and effectively demonstrate
whether a DE of greater than 99.9999 percent is achieved.
o A Trial Burn Waiver for PCBs
In the Tentative Determination, EPA proposed to authorize
the incineration of PCBs in the Vulcanus II based upon trial
burns by the Vulcanus I and the close similarity between the
incinerators on the two ships. The TSCA regulations provide
for a waiver of a PCB trial burn if a detailed comparison of
two incinerator systems convinces EPA that they will have an
equivalent destruction efficiency.
In permitting practice, however, the TSCA program has
required a trial burn for all land-based facilities burning
PCBs, and has never granted a waiver for a trial burn. In
order to be consistent with TSCA permitting practice, the
proposed regulations recommend that all vessels demonstrate
99.9999 percent DEs for PCBs, even if vessels with similar
incinerator systems have already done so.
o Destruction of Dioxin
In the Tentative Determination, EPA stated that the cir-
cumstances of the 1977 Test burn indicated that the Vulcanus
had achieved a DE greater than 99.99 percent for dioxin,
even though the calculated DE was greater than 99.93 percent.
- 29 -
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Some commenters questioned this determination. The proposed
regulations include a higher destruction efficiency requirement
for dioxins of 99.9999 percent. This can be demonstrated in
a trial burn by achieving a DE of 99.9999 percent for compounds
more difficult to incinerate than dioxins.
o
The Impact of Scrubbers on Hazardous Organic Emissions
Some commenters expressed concern about the absence of
scrubbers on the Vulcanus vessels, arguing that scrubbers
provided an extra margin of safety by removing some of the
hazardous organic compounds remaining in the flue gas. In
EPA's opinion, scrubbers do not control hazardous emissions.
Trial burns conducted by the RCRA program provide some data
on this question. At five plants with wet scrubbers, EPA
examined scrubber effluents for POHC contamination. Most
hazardous constituents were undetected, or were present in
very low concentrations (less than 20 ug/L). Generally,
quantities found in the effluents were small compared to
quantities emitted from the stack and did not significantly
improve ORE.
o The Effectiveness of the POHC System
The POHC system is used by both the land-based and ocean
incineration programs. A number of persons expressed concern
that this system, and particularly the heat of combustion
index, do not provide an adequate basis for determininq the
incinerability of a complex mixture of chemical comoounds.
EPA is continuing to assess the reliability of this system,
but believes it to be the best system currently available.
Recent data obtained by ORD does not substantiate the heat
of combustion and concentration-based method for ranking
compounds. Evidence seems to be mounting that any or all
organics may be destroyed essentially equally under a given
condition. However, the issue of selecting the appropriate
measure for a POHC ranking system becomes less important
when one considers that normal operating flame temperatures
which organic compounds are subjected to in land and ocean
incinerators are several hundred degrees higher than tempera-
tures needed to destroy any compounds at the top of all
investigated or considered hierarchies.
4.3 Hydrogen Chloride
4.3.1 Land-based Incineration
The combustion of chlorinated compounds in hazardous waste
incinerators results in chloride emissions, principally in the
form of hydrogen chloride (HC1). RCRA regulations limit HC1
emissions to either 1.8 kilograms per hour or 99 percent
removal. PCB regulations require the use of wet scrubbers
or an approved alternate, with specific performance requirements
to be specified by the Regional Administrator.
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As indicated in the discussion of control technology,
a wide variety of scrubber designs is used, with some using
water as an absorbing medium and others using a caustic
solution. In the incinerator test burn study conducted for
the RCRA program, the effectiveness of HC1 control was analyzed
for the five incinerators with control systems. Scrubber
systems were able to meet easily either the 99 percent removal
efficiency or the 1.8 kilogram per hour criteria specified
in the regulations.
4.3.2 Ocean Incineration
EPA does not reguire scrubbers for ocean incineration
ships. Although the proposed regulations for ocean incineration
include an environmental standard to limit HC1 impacts, it is
not expected that this standard will result in a need for
scrubbers on ships. EPA's position is that ship personnel
can be protected from any potential contact with HC1 by
setting appropriate rules about plume orientation and ship
forward speed. In addition, HC1 coming in contact with
seawater will be rapidly neutralized.
Analysis of seawater collected under the Vulcanus" plume
during the 1974-1975 test burn did not show a lowered pH due
to the HC1. When the Texas Air Control board examined data
from on shore monitoring for plume remnants during the August
1982 PCB burn, it found no evidence of HC1.
4.3.3 Issues
Generally, few concerns have been expressed regarding
the impact of HCl on the ocean, based on the current level
of burning. Two acid gas issues, however, were raised
during the public comment period:
o HCl May Contribute to Acid Rain
EPA scientists believe that most direct HCl emissions
from ocean incineration are mixed with ocean waters, and the
remainder is too distant from land to contribute to terrestrial
acid rain.
o The Release of Other Halogens
Some commenters on the ocean permits expressed concern
about potential environmental problems if elements such as
fluorine, iodine and bromine are released either as the free
element or as the acidic gas, HF, HI and HBr. EPA intends
to conduct environmental monitoring for these species during
future permits, and as a result of further investigation may
choose to limit the amounts of fluorine, iodine and bromine
in wastes incinerated in the future. This decision will be
based on evaluation 9f the atmospheric chemistry of these
materials and their impacts on the marine environment.
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4.4 Particulates
4.4.1 Land-based Incineration
Incineration of hazardous waste may result in particulate
emissions from the waste feed, auxiliary fuels, and scrubbing
liquids used in the air pollution control system. Ash from
the waste feed or auxiliary fuel may be emitted as a particu-
late in the exhaust gas. Carbonaceous material can also be
entrained in exhaust gases, condensed in air pollution control
systems, and emitted to the atmosphere. Particulates may
occasionally come out of water droplets evaporated in a quench
chamber or scrubber and then be contained in the exhaust
stream. RCRA incinerator regulations require particulates
to be controlled to less than 0.08 grain/dscf when corrected
to 7 percent oxygen in the stack gases. The PCB regulations
have no specific limitations for particulates.
The actual particulate loading for directly discharged
emissions will vary significantly as the characteristics of
the waste vary. For instance, liquid waste incinerators
would normally have smaller loadings than incinerators which
burn solid wastes in conjunction with liquids.
The technology used to control particulate matter is
well established and often features venturi scrubbers or
ionizing wet scrubbers. The specific technology chosen
depends upon the particulate loading, size distribution of
particulates, acid gas removal needs, and regulatory require-
ments.
Test data on a variety of hazardous waste incinerators
indicates that federal standards can be achieved with existing
control technology. Test burns conducted for the OSW regula-
tory impact analysis indicated that three of the five systems
examined with particulate controls achieved the federal standard,
ORD reports that scrubbers and other forms of pollution control
devices were found to be successful in meeting the particulate
standard when sophisticated systems were used, less successful
when low energy or less sophisticated systems were used.
4.4.2 Ocean Incineration
EPA does not require particulate emission controls for
ocean incineration. Since only liquid wastes are burned,
EPA expects the overall particulate loading to be very low.
In addition, EPA proposes to limit particulates by limiting
the amount of metals in the waste. A plume modeling exercise,
assuming all metals in the waste enter the environment, will
be used to set conservative limits ensuring that water quality
criteria for the metals would not be exceeded.
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4.4.3 Issue
in the past, EPA has not attempted to measure particulate
loadings for the Vulcanus burns and has received some criticism
for this. This issue is discussed further in section 5.2.3.,
on sampling.
4.5 Products of Incomplete Combustion (PICs)
4.5.1 Land-based Incineration
In the process of burning hazardous wastes, incinerators
and other combustion devices may cause the formation and
emission of potentially harmful substances that are not
present in the initial waste stream. Concern about the
creation of these substances, called products of incomplete
combustion (PICs), became acute in the late 1970's with the
discovery of chlorinated dioxins and furans in the emissions
of many incinerators burning municipal refuse and hazardous
wastes. A wide variety of other PICs has been found in
incinerator test burns. Currently there is a great deal of
uncertainty regarding the source of PICs or the mechanisms
by which they are formed. As yet, PIC emissions are unregu-
lated, although EPA proposed regulations on PICs under RCRA
in 1981.
Because of the potential hazard from emissions of chlori-
nated dioxins or furans, EPA has studied this issue closely.
In 1980, EPA sampled five municipal incinerators for dioxin
emissions and found both the emissions and human health risk
from the emissions quite low. At the same time, EPA evaluated
the formation of dioxins and furans during the incineration
of PCBs at the ENSCO and Rollins incinerators in El Dorado,
Arkansas, and Deer Park, Texas. Although low levels of both
PICs were found, a worst case risk analysis showed the incre-
mental human health risk for cancer to be in the range from
0.1 to 0.8 per million population, based on the point of
highest ambient air concentrations in a residential area.
Much uncertainty exists regarding how and why dioxins,
furans, and other PICs are formed in high temperature incine-
rators and other combustion devices. The test burn report
prepared for EPA as part of the Regulatory Impact Analysis
suggests three mechanisms may account for the presence of
PICs:
o Actual products of combustion reactions, whether from
specific organic precursors, or a complex series of
reactions of oxygen, carbon, and chlorine atoms.
o Compounds detected in the stack which were present in
the waste feed at levels just below the cut-off used
for waste feed analysis.
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o Compounds introduced to the system from some outside
source such as the scrubber water, in leak air, and
auxiliary fuel.
For all of the incinerators tested, the combustion re-
action alternative appears to account for the vast majority
of PICs. In general, the report concluded that stack gas
concentrations of PICs were typically as high as the concen-
tration of POHCs detected in the stacks, but rarely exceeded
0.01% of the POHC input rate. Of the six sites tested for
chlorinated dioxins and furans, dioxins were found at one
site and furans at three. Maximum concentrations were 0.06
ng/L of furans and 0.02 ng/L of dioxins.
4.5.2 Ocean Incineration
In previous ocean test burns, EPA found only trace
amounts of dibenzofurans, and in one instance, dioxin at
0.09 nanograms per cubic meter. Other potential PICs were
not investigated.
4.5.3 Issue
The identification and measurement of potentially harm-
ful PICs has become an issue for a wide range of combustion
sources including land-based and ocean incineration. PIC
emissions may be significant because, although they have
been identified in very trace guantities, they are also some
of the most toxic materials known; i.e., dioxins and furans.
Critics of the Vulcanus permits believe that the ocean
program should pay greater attention to PICs. The ocean
incineration regulations will address the issue by reguiring
that more research be done on identifying and analyzing PIC
emissions during research burns.
The RCRA program and ORD are also continuing research
into factors affecting PIC formation and control, and their
impacts on the environment. Because studies to date indicate
that reported levels of PICs from well operated hazardous waste
incinerators present very low risks, EPA has not regulated PICs,
4.6 Variables Affecting Combustion
4.6.1 Land-based Incineration
Incineration theory traditionally identifies four factors
critical for efficient incineration: sufficient oxygen, and
the three "Ts" of time, temperature and turbulence. The
wastes must be exposed to a temperature high enough to allow
complete oxidation of the organic materials, they must have
adequate time exposed to the hot temperatures, and they must
be mixed well enough to ensure that each molecule is exposed
- 34 -
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to enough oxygen molecules to allow complete oxidation.
Temperatures are usually measured by a thermocouple in the
combustion wall or in the gas stream. Residence time is
normally estimated based on combustion chamber volume, tem-
perature, and combustion gas flow rate in the system.
Turbulence is more difficult to measure, and practitioners
have not reached general agreement on a turbulence parameter.
When EPA first began to regulate incinerators, it specified
conditions, such as particular minimum values for temperature,
residence time, and oxygen (measured by "excess 02 in the
stack"). This approach is reflected in the TSCA Annex I
regulations (May 1979) for incineration of liquid PCBs, as
well as the provisions of the London Dumping Convention techni-
cal guidelines. The RCRA incinerator regulations were originally
proposed with specified operating conditions, but this approach
was abandoned in favor of performance standards with operating
conditions specified on a permit by permit basis. One of the
major reasons for the performance standards approach under
RCRA was the growing recognition that not enough is known
about how design and operating parameters affect performance
for EPA to specify those parameters in a definitive way.
4.6.2 Ocean Incineration
The Vulcanus incinerators operate in the temperature
range of 1166°C to 1600°C, with a residence time on the
order of one second, and excess oxygen in the 5-15 percent
range. In establishing operating conditions in the proposed
permits, EPA's Office of Water has relied primarily on the
RCRA performance standard approach. However, minima for
wall temperature, oxygen in the stack gas, and CE, a maximum
for carbon monoxide in the stack gas, and residence time
requirements are also established, as those are required
under the London Dumping Convention Incineration Regulation
and Technical Guidelines. Separate operating requirements
and a DE performance standard are set for wastes containing
PCBs.
4.6.3 Issue
In this area, the primary issue has been the adequacy of
the one-second residence time achieved by the Vulcanus incine-
rators. Some commenters feel this provides inadequate combustion
time for PCB wastes, which are subject under TSCA regulations
to a 2 second residence time at Vulcanus operating temperatures.
EPA's view is that the capability of the ocean incinerators
is best measured directly through performance by destruction
efficiency, under operating conditions established during
trial burns as under the RCRA regulations. EPA believes
its experience with a wide range of test burn data under the
TSCA program shows that a residence time of two seconds is
not necessary for adequate PCB destruction.
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Under the RCRA program, permit operating conditions are
based on actual conditions achieved during the trial burn,
and therefore, are not a major issue. Under the TSCA program,
minimum temperature and residence time are required, but the
operating parameters may be waived if a 99.9999 percent
destruction efficiency is achieved during a trial burn. In
practice, the TSCA program has provided waivers for several
incinerators achieving the required destruction efficiency,
but with dwell times less than the 2 seconds specified in
the regulation. All of the land-based waivers have been for
existing on-site incinerators with low concentrations of PCBs
in their waste feed; no commercial, off-site incinerators
have received waivers.
5. SAMPLING AND MONITORING
This section provides an overview of sampling and monitoring
requirements and procedures for both land-based and ocean
incineration. Issues raised with regard to specific procedures
are also covered.
5.1 Campling and Monitoring Procedures for Land-Based
Incinerators
Sampling techniques and analysis methods for incinerator
emissions used for the trial burn are generally taken from
EPA recommended methods found in 40 CFR Part 60 Appendix A -
Methods 1-5, and Test Methods for Evaluating Solid Waste:
Physical/Chemical Methods (SW-846, Second Edition, July 1982),
or in the EPA document, Sampling and Analysis Methods for
Hazardous Waste Combustion (Arthur D. Little, Inc., EPA-600/
8-84-002, February 1984).
Typical sampling and monitoring locations for a liquid
injection incinerator are indicated in Figure 5.1. Compre-
hensive sampling and monitoring during the trial burn are
essential for documenting compliance with the performance
standards and developing the conditions of the permit.
Sampling and monitoring data from the trial burn must be
sufficient to provide for:
o quantitative analysis of the POHCs in the waste feed
to the incinerator;
o quantitative analysis of the stack exhaust gas for
the concentration and mass emissions of the POHCs
o quantitative analysis of the scrubber water, ash, and
other residues for the POHCs;
o computation of destruction and removal efficiency
(ORE);
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o computation of HCL removal efficiency (if emissions
exceed 1.8 kilograms per hour);
o computation of particulate emissions;
o identification of sources of fugitive emissions;
o average, maximum and minimum combustion temperature
and gas velocity;
o continuous measure of carbon monoxide (CO) in the
exhaust gas.
5.1.1 Routine Sampling and Monitoring
Following the trial burn, the facility receives a permit
for ongoing operations which specifies waste analysis and
monitoring requirements. Routine waste analysis requirements
will vary for different facilities. For example, an incinerator
that only burns wastes generated from one manufacturing pro-
cess may have less stringent requirements than a commercial
incinerator that burns wastes from a variety of sources. A
waste analysis plan must be developed which allows for periodic
verification that the waste feed is within permit-specified
physical and chemical composition limits.
RCRA permits require continuous monitoring for temperature,
carbon monoxide, waste feed rate and combustion gas velocity.
5.1.2 Automatic Waste Feed Cutoff
An automatic waste feed cutoff system is required to shut
off waste feed to the incinerator whenever certain operating
parameters deviate from the limits set in the permit. To
accomplish this, the cutoff valves are interlocked to all
of the required continuous monitoring devices (temperature,
carbon monoxide, waste feed rate and combustion gas velocity).
For each operating parameter, the permit should establish a
range of operation and a level, somewhat beyond that range,
at which the emergency waste feed cutoff system must be
activated. The permit writer generally selects the ranges
on the basis of trial burn data. At least weekly testing of
the cutoff system is required.
5.1.3 Ambient Monitoring
Under RCRA and TSCA, no ambient monitoring is required
for land-based incinerators. All routine monitoring is for
stack emissions. In some cases, states may require ambient
monitoring under the Clean Air Act.
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5.1.4 Issue
The land-based hazardous waste incineration program does
not require ambient monitoring. EPA's risk studies indicate
that if stack emissions are verified to be within regulatory
limits, human health and environmental impacts will be very
small. Additionally, in many locations accurate and reliable
testing for ambient air effects around land-based incinerators
is not feasible due to extremely low concentrations and
interference from other industrial activities.
5.2 Sampling and Monitoring Procedures for Ocean Incineration
During the ocean trial burns, sampling and analysis of
stack gases to determine the DE on POHCs and in determining
emission levels of PICs must be done according to EPA sampling
and analysis methods described in 40 CFR part 60. Sampling
techniques and analysis methods for wastes are taken from
Test Methods for Evaluating Solid Wastes (SW-846, Second
Edition, July 1982) or Sampling and Analysis Methods for
Hazardous Waste Combustion (Arthur D. Little, Inc.,
EPA-600/8-84-002 February 1984). During routine burning
operations, CE is used as the measure for gauging incinerator
performance. Continuous monitoring of wall temperature,
oxygen, carbon dioxide, carbon monoxide, waste flow, and air
flow to the combustion chamber is required.
5.2.1 Automatic Waste Feed Cutoff
Automatic waste feed cutoff devices are linked to minimum
wall temperature, flame-out, minimum oxygen in combustion
gas, maximum carbon monoxide in combustion gas, and failure
of monitoring devices for temperature, air flow, oxygen in
combustion gas, carbon monoxide in combustion gas, carbon
dioxide in combustion gas, and waste and auxiliary fuel
flow. As with land-based incinerators, the ocean permits
establish the level at which the cutoff system is activated.
Instrument calibration and testing according to manu-
facturer's specifications is required before each cruise for
devices measuring carbon monoxide, carbon dioxide, oxygen,
wall temperature, waste flow and auxiliary fuel, and air
flow as well as for the waste feed cutoff system.
5.2.2 Ambient Monitoring
Environmental monitoring studies have been conducted to
varying degrees during past ocean burns. In these studies,
EPA has not been able to detect any increase in background
levels of PCBs, dioxin, or POHCs in the ambient air, water
or marine biota samples collected. Proposed regulations
will require comprehensive environmental monitoring studies
to be conducted by applicants prior to issuance of permits.
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5.2.3 Other Monitoring
Other monitoring reguirements include keeping records
of times and dates of burns, wind speed and direction, and
vessel position, course, and speed.
5.3 Issues
Table 5.2 recaps the issues that have been raised by
critics of ocean incineration regarding sampling and monitoring
procedures carried out during past ocean burns. The most
significant issues are discussed in further detail in the
following sections.
5.3.1 Stack Gas Sampling
In past burns EPA has required that stack gas be sampled
using methods consistent with 40 CFR part 60 methods for
sampling stationary sources. The best method is acknowledged
to be the sample/velocity traverse. The traverse calls for
a sampling probe to be inserted in the stack and moved
horizontally along two perpendicular diameters. Samples are
to be collected at twelve points along each diameter. Each
sampling point is indicative of an egual cross-sectional area
of the stack from the center of the stack outwards. Thus the
time that the sampling probe collects from each point is
equal.
Partial stack traverses have been done on two series of
burns. Critics have pointed out several inadequacies in
conducting them which they charge have resulted in inaccurate
measures of incinerator performance. Moreover, the results
of the traverses have been used by EPA as a basis for deter-
mining that a fixed point sampling method could be used in
subsequent burns. This method calls for the sampling probe
to be inserted at a single stack location thought to provide
the most representative sample of stack gas. Again, critics
charge that there is inadequate data from the traverses to
select a fixed point, and, thus, measurements from the fixed
point have not yielded data that is representative of emissions.
A constraint that has inhibited stack traversing on the
M/T Vulcanus I is inherent in the method of sampling itself.
The method was originally devised for stationary, land-based
sources where the flow regime (i.e. laminar vs. turbulent)
was unknown. For land-based incinerators with scrubbers,
combustion gas is cooled and slowed down, making stack traversing
an easier operation to carry out. Moreover, working conditions
on a short stack emitting hot gases on a continuously moving
vessel make it more difficult to physically carry out this
method at sea.
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Critics have also claimed that flow disturbances within
the incinerator will affect measurements taken from a fixed
point probe. EPA maintains that flow disturbances are
irrelevant because of the turbulent gas swirl characteristic
of ocean incinerator desiqn.
After reviewing the public comments, EPA has concluded
that the basis for choosing the fixed point sampling location
was adequately demonstrated during previous stack traverses.
However, because of the many comments received expressing
concern on this issue, conclusive traversing of the stack
would be required under the currently proposed regulations.
5.3.2 Sampling for Particulates
Critics have said that surviving POHCs and PICs
may be emitted from stacks by adsorbing on minute solid
particulate matter such as ash, metals or from thermal cor-
rosion of firebrick. They claim that isokinetic sampling
should be done to quantify particulates in order to provide
a more complete measure of DE. EPA believes that at elevated
temperatures, virtually all POHCs and PICs exist as free
gaseous molecules or vapors, and as such are adeguately
monitored using standard traversing procedures. However, to
confirm this to the extent possible, EPA proposed regulations
would require that quantitative samples be collected using
isokinetic sampling which will be approprimately modified
for consideration of ocean incineration characteristics.
This paper presents a comparison of the major technical
features of land-based and ocean incineration. Our objectives
are to provide a sound technical background summary and to
illuminate areas of controversy by matching key issues with
available technical information. The discussion encompasses
major design elements, waste handling features, and characteristic
emissions from each technology. It does not include an
assessment of the human health or environmental impacts of
the technologies because that is the primary work of the
comparative risk assessment paper.
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LIST OF REFERENCES
1. At-Sea Incineration of Herbicide Orange Onboard the M/T
Vulcanus, EPA Report 600/2-78-086, April 1978.
2. At-Sea Incineration of Organochlorine Wastes Onboard
the M/T Vulcanus, EPA Report 600/2-77-196, September
1977.
3. At-Sea Incineration of PCB Containing Wastes Onboard the
M/T Vulcanus, EPA Report 600/7-83-024, April 1983.
4. Background Document on The Tentative Determination to
Issue Incineration-At-Sea Permits, October 1983.
5. Gerald 0. Chapman, et. al., "Chemical Waste Incinerator
Ships: The Interagency Program to Develop a Capability
in the United States," Marine Technology, 19, 4,
pp. 325-40.
6. Comments on the Central States, Southeast and Southwest
Area Pension Fund on the Tentative Determination to
Issue Incineration-At-Sea Permits, January 1984.
7. Composition of Hazardous Waste Streams Currently Incinerated
MITRE Corporation. EPA Contract 68-01-6092. April 1983.
8. Disposal of Organochlorine Wastes by Incineration-At-Sea,
EPA Report 430/9-75-014, July 1975.
9. Eugene P. Grumpier, "Ensuring Thermal Destruction of Dioxins
"To What Level," undated paper.
10. Eugene P. Grumpier and Edward J. Martin, "Incineration of
Hazardous Waste," undated paper.
11. Engineering Handbook for Hazardous Waste Incineration.
Monsanto Research Corporation. EPA Contract 68-03-3025.
July 1981.
12. Vincent G. Grey, President SeaBurn Inc., Statement at
Hearings of the Subcommittee on Fisheries and Wildlife
Conservation and the Environment, December 7, 1983.
13. Guidance Manual for Hazardous Waste Incinerator Permits.
OSWER, EPA. (SW-966), July 1983.
14. Guidelines for the Disposal of PCBs and PCB Items by
Thermal Destruction, EPA Report 600/2-81-022, February
1981.
15. Hazardous Waste Incineration - A Profile of Existing
Facilities. MITRE Corporation. EPA Contract 68-03-3021.
July 26, 1982.
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16. Hazardous Waste Incineration: Profile of Manufacturers.
MITRE Corporation. EPA Contract 68-03-3021. June
1982.
17. Hazardous Waste Stream Trace Metal Concentrations and
Emissions. MITRE Corporation. EPA Contract 68-01-6092.
November 1983.
18. Hearing Officer's Report on The Tentative Determination
to Issue Special Ocean Incineration Permits and a
Research Permit to Chemical Waste Management, Inc. and
Ocean Combustion Services, BV, April 23, 1984.
19. David A. Hitchcock, "Solid-waste Disposal: Incineration,"
Chemical Engineering, May 21, 1979, pp. 185-194.
20. Incineration of Volatile Organic Compounds on the M/T
Vulcanus II. TRW Report dated April, 1983.
21. Incinerator Regulatory Impact Analysis. Draft. PEER
Consultants. EPA Contract 68-01-6673. December 1983.
22. Installation and Operation of Hydrocarbon and Carbon
Monoxide Monitors on Hazardous Waste Incinerators.
MITRE Corporation. EPA Contract 68-01-6092. April
1983.
23. Interim Report on Hazardous Waste Incineration Risk
Analysis (DRAFT). Industrial Economics Incorporated.
August 1982.
24. Merrill Jackson memo, "Review of Reports of At-Sea
Incineration Onboard the M/T Vulcanus II," June 25,
1983.
25. Yen-Hsiung Kiang and Amir A. Metry, Hazardous Waste
Processing Technology, Ann Arbor, Michigan: Ann Arbor
Science, 1982.
26. L. Kokoszka and G. Kuntz, "Methods of PCB Disposal," US
EPA, Office of Pesticides and Toxic Substances.
27. Liguid Injection Hazardous Waste Incinerator Burner
Performance. MITRE Corporation. EPA Contract 68-01-6092.
October 1983.
28. Henry Marcus and Charles T. Daniel, Logistical Systems
to Support Ocean Incineration of Liquid Hazardous
Wastes, Massachusetts Institute of Technology, August
1982.
29. Monitoring of Combustion Efficiency and Destruction Efficiency
During the Certification Voyage of the Incineration Vessel
"Vlucanus-II", January 1983. TNO Report R 83/53, March 24,
1983.
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30. Performance Evaluation of Full Scale Hazardous Waste
Incinerators. Volume II. Draft Final Report. Midwest
Research Institute. EPA Contract 68-02-3177. January
1984.
31. Report of the Interagency Ad Hoc Work Group for the
Chemical Waste Incinerator Ship Program, September
1980.
32. Sampling and Analysis Methods for Hazardous Waste Combustion,
Arthur D. Little, Inc., EPA-600/8-84-002, February 1984.
33. David Stephan memo, "Recommended Operating Parameters, Past
Performance Reliability Considerations, and Similarity
Considerations for Vulcanus I and II," August 10, 1983.
34. Technologies and Management Strategies for Hazardous Waste
Control, Office of Technology Assessment, March 1983.
35. Patrick Tobin memo to Steven Schatzow, "Public Comments
on the Proposed Ocean Incineration Permits and the
Schedule for the Hearing Officer's Report, February
24, 1984.
36. Richard Wills letter and supporting documents to Pat Tobin
regarding At-Sea Incineration Application for an Ocean
Incineration Research Rurn Permit, December 20, 1983.
37. Draft Proposed Rule on the Ocean Incineration Regulation,
40 CFR Part 232, September 7, 1984.
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TT S, fevviroruta'-uta^ ;:
-jglon 5, Library (..<~j, . .
£30 S. Doarborn itreet, Room
Chicago, IL 60604
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