United States
Environmental Protection
Agency
Off tea of Water
(WH-586)
EPA 822/R-93-003
November 1992
XVEPA Technical Support Document
for Sewage Sludge
Incineration
-------
TECHNICAL SUPPORT DOCUMENT
FOR
SEWAGE SLUDGE INCINERATION
Prepared for
Office of Water
U.S. Environmental Protection Agency
401 M Street SW
Washington, DC 20460
Prepared by
Eastern Research Group
110 Hartwell Avenue
Lexington, MA 02173
November 1992
-------
Acknowledgments
This document was prepared by Eastern Research Group, Inc. (ERG) for the U.S.
Environmental Protection Agency's Health and Ecological Criteria Division of the Office of Water.
The following ERG staff contributed to the writing, editing, and production of this document:
Anne Jones Project Manager
Scott Cassel Task Manager/Writer
John Bergin Copyeditor/Production Coordinator
ERG staff would like to thank Dr. Alan Rubin for his guidance and support as EPA Project
Manager. We would also like to thank Robert Southworth, Mark Morris, and Cris Gaines of the
Office of Water, and Gene Grumpier of the Office of Air Quality, Planning and Standards for their
useful comments and valuable insights on various aspects of this study.
-------
CONTENTS (conL)
Page
5.33.3 Cancer Potency 5-9
5.3.3.4 Inhalation Rate 5-10
5.4 Derivation of Risk-Specific Concentrations for the Carcinogenic Metals 5-11
5.4.1 Risk-Specific Concentration Calculations for Arsenic and Cadmium .... 5-12
5.4.2 Risk-Specific Concentration Calculation for Chromium 5-13
5.4.3 Risk-Specific Concentration Calculation for Nickel 5-16
5.5 Use of a Percentage of the National Ambient Air Quality Standard for Lead ... 5-17
5.6 Derivation of the Limits on the Concentration of Arsenic,
Cadmium, Chromium, Lead, and Nickel in Sewage Sludge 5-18
5.6.1 Dispersion Factor 5-19
5.6.1.1 Model Selection 5-20
5.6.1.2 Source Parameters 5-21
5.6.1.3 Good Engineering Practice Stack Height 5-21
5.6.1.4 Building Downwash Factor 5-23
5.6.1.5 Meteorological Data 5-23
5.6.1.6 Model Availability 5-24
5.6.2 Control Efficiency 5-25
5.63 Sewage Sludge Feed Rate 5-26
5.6.4 Example of Calculation for the Arsenic Limit 5-26
5.6.5 Example of Calculation for the Lead Limit 5-27
5.7 Pollutant Limits for Beryllium and Mercury 5-28
SECTION SIX DEVELOPMENT OF THE OPERATIONAL STANDARD
FOR TOTAL HYDROCARBONS 6-1
6.1 THC as a Surrogate for Organic Emissions 6-1
6.2 Statutory Basis for Using an Operational Standard 6-6
6.3 Basis for the THC Operational Standard 6-7
6.4 Correction Factors for Oxygen and Moisture Content and
a Sample Calculation for the THC Concentration 6-10
6.5 Risk Posed by the THC Operational Standard 6-13
6.5.1 Equations Used to Determine the Degree of Risk 6-14
6.5.2 Derivation of Estimated Site-Specific RSC Values for THC 6-17
6.52.1 Dispersion Factor 6-18
6.52.2 Gas Flow Rate 6-18
6.523 Conversion Factor 6-20
6.52.4 Example of a Calculation to Derive a Site-Specific RSC Value ... 6-22
6.53 Estimate of Public Health Protection Regarding the THC
Operational Standard 6-22
6.53.1 Derivation of a Weighted Cancer Potency Value for THC 6-23
6.532 Example of a Calculation Used to Evaluate the Risk Level
for the THC Operational Standard 6-25
-------
CONTENTS (cont)
Page
SECTION SEVEN MANAGEMENT PRACTICES 7-1
7.1 Instrument for Measuring Total Hydrocarbons in Stack Gas 7-1
7.2 Instrument for Measuring Oxygen Concentration in Stack Gas 7-3
7.2.1 Excess Air Rate 7-3
7.2.2 Oxygen Monitors 7-4
7.3 Measuring Moisture Content in Stack Gas 7-5
7.4 Combustion Temperature 7-7
7.5 Operating Parameters for Air Pollution Control Devices 7-8
7.6 Threatened or Endangered Species 7-9
SECTION EIGHT FREQUENCY OF MONITORING, RECORDKEEPING, AND
REPORTING
8-1
8.1 Frequency of Monitoring 8-1
8.2 Recordkeeping 8-1
8.3 Reporting 8-3
SECTION NINE REFERENCES 9-1
APPENDIX A STANDARDS FOR THE USE OR DISPOSAL OF
SEWAGE SLUDGE A-l
Subpart A—General Provisions
Subpart E—Incineration
APPENDIX B SEWAGE SLUDGE INCINERATORS SUBJECT
TO PART 503 (as of October 27,1992) B-l
.APPENDIX C RATIO OF HEXAVALENT TO TOTAL CHROMIUM
INCINERATION EMISSION C-l
APPENDIX D SUMMARY OF NICKEL SPECIATION EMISSION TESTS
AT THREE SEWAGE SLUDGE INCINERATORS D-l
APPENDIX E GENERAL GUIDELINES FOR CONDUCTING A
PERFORMANCE TEST AT A SEWAGE SLUDGE
INCINERATOR TO DETERMINE THE CONTROL
EFFICIENCY E-l
vi
-------
CONTENTS (coot)
Page
APPENDIX F EMISSIONS DATA FOR THC, CO, AND 21
ORGANICS FROM FOUR SEWAGE SLUDGE
INCINERATORS F-l
APPENDIX G STATISTICAL SUPPORT FOR THE PROPOSED
REGULATORY LEVEL ON TOTAL HYDROCARBON
EMISSIONS FROM THE INCINERATION OF
SEWAGE SLUDGE G-l
APPENDIX H A STATISTICALLY DEFENSIBLE ESTIMATE OF
THE DIFFERENCE BETWEEN A SAMPLE OF TOTAL
HYDROCARBON EMISSIONS MEASURED WITH HEATED
SAMPLE LINES AND THE SAME SAMPLE MEASURED
WITH UNHEATED SAMPLE LINES H-l
APPENDIX I MOLECULAR WEIGHTS AND RESPONSE FACTORS FOR
ORGANIC COMPOUNDS USED TO DEVELOP A qj* FOR THC . 1-1
APPENDIX J CALCULATIONS TO DERIVE SITE-SPECIFIC
RISK-SPECIFIC CONCENTRATIONS AND RISK
LEVELS AT THE 23 SEWAGE SLUDGE INCINERATORS
IN THE NATIONAL SEWAGE SLUDGE SURVEY J-l
APPENDIX K WEIGHTED CANCER POTENCY RISK FACTOR FOR THC ... K-l
APPENDIX L EMISSIONS DATA FOR ORGANIC COMPOUNDS USED
TO DERIVE THE q,« FOR THC L-l
APPENDIX M PERFORMANCE INDICATOR PARAMETERS FOR AIR
POLLUTION CONTROL DEVICES M-l
APPENDIX N CALCULATION OF THE AMOUNT OF SEWAGE SLUDGE
USED OR DISPOSED N-l
VH
-------
LIST OF UNITS AND ACRONYMS
APCD air pollution control device
Btu British thermal unit
BW human body weight (kg)
cal calories
CFR Code of Federal Regulations
CO carbon monoxide
CWA Clean Water Act
DF dispersion factor (/ig/mVg/second)
dmt dry metric ton
EPA U.S. Environmental Protection Agency
ERG Eastern Research Group, Inc.
ESP electrostatic precipitator
FBF fluidized-bed furnace
FC fuel constant
FGF fuel combustion gas flow rate (g-moles/day)
FID flame-ionization detector
FR annual average daily fuel usage rate (Ib/day or ftVday)
ft2 square feet
ft5 cubic feet
g gram
GF gas flow rate (g-moles/day)
hr hour
I, inhalation rate
in2 square inches
IRIS Integrated Risk Information System
ISCLT Industrial Source Complex Long-Term model
kg kilogram
kFa kilopascals
L liter
Ib pound
LC50 inhalation dose (concentration of chemical) at which SO percent of study animals
die
LDj,, oral dose of chemical at which 50 percent of study animals die
LOAEL Lowest Observed Adverse Effect Level (mg/kg»day)
LOEL Lowest Observed Effect Level (rag/kg • day)
m meter
MCL maximum contaminant level
rag milligram
MGD million gallons/day
MHF multiple-hearth furnace
MTD maximum tolerated dose
NAAQS National Ambient Air Quality Standard
NAS National Academy of Sciences
NESHAPs National Emission Standards for Hazardous Air Pollutants
ng nanogram
NIOSH National Institute for Occupational Safety and Health
a.
-------
LIST OF UNITS AND ACRONYMS (cont.)
NOAEL No Observed Adverse Effect Level (mg/kg»day)
NOEL No Observed Effect Level (mg/kg«day)
NPDES National Pollution Discharge Elimination System
NSSS National Sewage Sludge Survey
OST Office of Science and Technology, EPA
OS W Office of Solid Waste, .EPA
OWRS Office of Water Regulations and Standards, EPA
PCBs polychlorinated biphenyls
PICs products of incomplete combustion
POTW publicly owned treatment works
ppm parts per million
ppmv parts per million, volume
qt* human cancer potency (mg/kg»day)
r2 correlation coefficient
RACs reference air concentrations
RCRA Resource Conservation and Recovery Act
RfC reference concentration of inhalation exposure
RfD oral reference dose (mg/kg»day)
RL site-specific risk level (unitless)
RSC risk-specific concentration Otg/m3)
RSC,,, site-specific risk-specific concentration for THC (jig/m3)
sec second
SF average daily amount of sewage sludge (drat/day)
SGF gas flow rate attributable to the combustible portion of sewage sludge
(g-moles/day)
SRAB Sludge Risk Assessment Branch, EPA
TCPD tetrachlorinated paradioxin
THC total hydrocarbons
TSCA Toxic Substances Control Act
ju, microns
pig microgram
VEHC annual average heat value of volatile solids in sewage sludge (Kcal/g-volatile solids
in sewage sludge)
VF annual average volatile solids fraction of sewage sludge solids (unitless)
WESP wet electrostatic precipitator
X percent moisture content in the sewage sludge incinerator stack exit gas, in
hundredths (volume/volume)
Y percent oxygen concentration in the sewage sludge incinerator stack exit gas
(volume/volume)
-------
LIST OF TABLES
Page
2-1 Air Pollution Control Devices by Furnace Type 2-14
4-1 Pollutants Selected for Environmental Profiles/Hazard Indices 4-3
4-2 Pollutants Evaluated and Found Not to Cause an Adverse Effect
on Human Health for Sewage Sludge Fired in a Sewage
Sludge Incinerator 4-7
4-3 Pollutants Deferred Because of Insufficient Data to
Conduct a Risk Assessment for Sewage Sludge Fired in a
Sewage Sludge Incinerator 4-8
4-4 Pollutants Selected for Environmental Profiles/Hazard Indices
That Are Regulated Under Part 503 Through the Total
Hydrocarbons Standard 4-9
4-5 Pollutants Regulated Under Part 503 for Sewage Sludge
Fired in a Sewage Sludge Incinerator 4-11
5-1 Cancer Potency Values (q,*) for Metals 5-10
5-2 Risk-Specific Concentrations for Metals 5-11
5-3 Percentage of Hexavalent Chromium to Total Chromium by
Furnace Type and Air Pollution Control Device 5-15
6-1 Correlation Between THC and Total Organics—Summary
Emissions Data from Four Sewage Sludge Incinerator Units 6-3
6-2 Summary of Total Hydrocarbons Emissions Measured with a
"Cold" Monitor and Adjusted to 7-Percent Oxygen 6-9
6-3 Risk Levels and Other Data for 23 Sewage Sludge
Incinerators Calculated from Data Provided by the 1988
National Sewage Sludge Survey (Based on 100 ppm THC) 6-15
8-1 Frequency of Monitoring^Incineration 8-2
C-l Descriptive Statistics on the Ration of Hexavalent
Chromium to Total Chromium in Incinerator Emissions C-4
C-2 Emission Limitations for the Percent of Hexavalent
Chromium in Total Chromium C-6
XI
-------
LIST OF TABLES (coat)
G-l Summary of Total Hydrocarbon Emissions Adjusted to
7-Percent Oxygen by Site and Operating Conditions:
Sample Sizes and Empirical Percentiles G-4
Xll
-------
LIST OF FIGURES
Page
2-1 Cross-Section of a Multiple-Hearth Furnace 2-4
2-2 Cross-Section of a Fluidized-Bed Furnace 2-8
2-3 Cross-Section of an Electric Infrared Furnace 2-11
2-4 Venturi/Irapingement-Tray Scrubber .. .". 2-16
2-5 Countercurrent-Flow Spray Chamber Scrubber 2-19
2-6 Cyclone Separator—Double Vortex Path of the Gas Stream 2-21
2-7 Wet Electrostatic Precipitator 2-24
2-8 Fabric Filter with Mechanical Shaking 2-26
2-9 Direct-Flame Afterburner 2-30
6-1 Total Hydrocarbon Concentration (THC) vs. Total Organics
Concentration of Volatiles and Seraivolatiles Detected in
Four Sewage Sludge Incinerators 6-4
7-1 Saturated Water Vapor Content of Flue Gas 7-6
xi u
-------
SECTION ONE
INTRODUCTION
1.1 BACKGROUND
Treatment works generate sewage sludge from domestic sewage in the process of
maintaining the quality of our water resources. The sewage sludge must then be used or
disposed in a manner that does not adversely impact public health or the environment. Sewage
sludge is used or disposed of in a number of ways, including land application, surface disposal,
incineration, and co-disposal with municipal solid waste. This document discusses the
incineration of sewage sludge.
EPA's role is to control the potential adverse effects to public health and the
environment that any use or disposal of sewage sludge may cause. Existing federal regulations
are authorized under several legislative mandates and have been developed independently along
media-specific concerns to regulate sewage sludge use and disposal. Section 405(d) of the Clean
Water Act (CWA), as amended (33 U.S.C. 1345), directed the Agency to develop, propose, and
promulgate regulations establishing standards for the use or disposal of sewage sludge.
Additional authorizing legislation includes sections of the Clean Air Act, the Resource
Conservation and Recovery Act (RCRA), and the Toxic Substances Control Act (TSCA).
In 1979, EPA responded to these mandates and promulgated criteria for using non-
hazardous solid wastes, including sewage sludge when it is applied to land or disposed in landfills.
These criteria were incorporated into 40 CFR Part 257, Criteria for Classification of Solid Waste
Disposal Facilities and Practices, which contained specific requirements for managing sewage
sludge. Any use or disposal of sewage sludge that caused the concentration of 10 inorganic and
6 organic chemicals in an underground drinking water source to exceed specified maximum
contaminant levels (MCLs) was prohibited. Management standards for using or disposing of
sewage sludge were set so that surface waters, flood plains, and endangered species were
1-1
-------
protected. Part 257 also established annual and cumulative rates (kg/ha) for cadmium and a
numerical concentration of polychlorinated biphenyls (PCBs) in sewage sludge and pathogen
reduction requirements for sewage sludge applied to land used for the production of animal feed
or food-chain crops.
In 1982, the EPA established an Intra-Agency Sludge Task Force to recommend
procedures for implementing a comprehensive regulatory program for sewage sludge
management. The Task Force recommended that such a regulatory program be developed using
the combined authorities of Section 405 of the CWA and other existing regulations so that
comprehensive coverage could be provided. Accordingly, a regulation was recommended that
would provide technical criteria for the use or disposal of sewage sludge.
The Office of Water Enforcement and Compliance proposed State Sludge Management
Program Regulations (U.S. EPA, 1986a). These regulations proposed that states develop
management programs that comply with existing federal criteria for the use or disposal of sewage
sludge. The proposed State Sludge Management Program Regulations focused on the
procedural requirements for submission, review, and approval of state sewage sludge
management programs. On March 9,1988, these regulations were proposed again (U.S. EPA,
1988a) to reflect changes in requirements for sewage sludge management programs imposed by
the 1987 Water Quality Act. After public comment, these regulations were promulgated under
40 CFR Part 501 on May 2,1989.
EPA began the task of preparing a comprehensive sewage sludge regulation in 1979
with the promulgation of 40 CFR Part 257, which included technical criteria. The overall task of
completing the comprehensive sewage sludge regulation was transferred to the Office of Water in
1984. A Wastewater Solids Criteria Branch was established under the Office of Water
Regulations and Standards (OWRS) within the Office of Water to develop the risk assessment to
support the rule. After the Office of Water was reorganized, the OWRS was renamed the Office
of Science and Technology (OST), and the Wastewater Solids Criteria Branch was renamed the
Sludge Risk Assessment Branch (SRAB). The SRAB developed the Part 503 regulation.
1-2
-------
Traditionally, the Agency uses the standards, definitions, and approaches developed under
other federal public health and environmental programs when they are consistent with the goals
and objectives of the CWA. Such an approach minimizes duplicative, overlapping, and
conflicting policies and programs. One principle followed in the Part 503 rule was to base
pollutant limits on human health and environmental criteria established under other statutory
authorities. Regarding sewage sludge incinerators, two statutes are referenced in the Part 503
rule. The National Ambient Air Quality Standard (NAAQS) for lead (40 CFR Part 50.12),
promulgated under authority of the Clean Air Act, was used in developing the pollutant limit for
lead when sewage sludge is fired in a sewage sludge incinerator. The National Emission
Standards for Hazardous Air Pollutants (NESHAPs) for beryllium and mercury, developed under
the authority of the Clean Air Act (40 CFR Part 61), are the pollutant limits for beryllium and
mercury in Part 503.
1.2 DESCRIPTION OF PART 503
The Part 503 standards consist of five Subparts. Subpart A contains General Provisions
that apply to each of the three sewage sludge use or disposal practices. Subparts B and C
pertain to specific requirements for the land application and surface disposal of sewage sludge,
respectively, while Subpart D, Pathogens and Vector Attraction Reduction, contains the
requirements for pathogenic organisms in sewage sludge and the requirements to reduce the
attraction of vectors, such as rodents, flies, and mosquitoes, which are capable of transporting
infectious agents. Subpart E contains the requirements for sewage sludge incineration.
This section (Section One) provides an overview of Subpart A, General Provisions, and
Subpart E, the sewage sludge incineration requirements. The text of both Subparts appears in
full as Appendix A. Although much of the General Provisions section is relevant to all the
regulated use or disposal practices, it also contains references that are specific to each practice.
This discussion will focus on the general and specific requirements affecting sewage sludge
incineration. Where there is overlap between the requirements of these two subparts as they
affect sewage sludge incineration, the information will be presented in the General Provisions
section.
1-3
-------
1.2.1 General Provisions
Subpart A of Part 503, General Provisions, consists of nine basic parts: the purpose and
applicability of the regulation; the compliance period; permits and direct enforceability; the
relationship to other regulations; additional or more stringent requirements; exclusions; the
requirement for a person who prepares sewage sludge; sampling and analysis; and general
definitions.
1.2.1.1 Purpose tout Applicability
Part 503 establishes standards for the final use or disposal of sewage sludge generated
during the treatment of domestic sewage in a treatment works. For sewage sludge fired in a
sewage sludge incinerator, the Subpart E consists of general requirements; pollutant limits; an
operational standard; management practices; and frequency of monitoring, recordkeeping, and
reporting requirements that protect public health from the reasonably anticipated adverse effects
of pollutants in sewage sludge. These elements of the standard are discussed in Subpart E,
which includes pollutant limits for arsenic, beryllium, cadmium, chromium, lead, mercury, and
nickel. Subpart E also includes an operational standard for total hydrocarbons that, in the
judgment of EPA's Administrator, protects public health from reasonably anticipated adverse
effects of organic pollutants in the exit gas from a sewage sludge incinerator stack. In addition,
Subpart E includes frequency of monitoring and recordkeeping requirements, as well as reporting
requirements for sewage sludge incinerators considered Class I sludge management facilities and
treatment works with flow rates equal to or greater than one million gallons per day or that serve
a population of 10,000 people or greater.
As it pertains to sewage sludge incineration, Part 503 applies to the person who prepares
sewage sludge; the person who fires sewage sludge in a sewage sludge incinerator; to sewage
sludge fired in a sewage sludge incinerator, to the sewage sludge incinerator, and to the exit gas
from a sewage sludge incinerator stack.
1-4
-------
1.2.1.2 Compliance Period
Compliance with the Part 503 sewage sludge incineration standards has to be achieved as
expeditiously as practicable, but in no case later than one year from the date of publication in
the Federal Register. If compliance with the standards requires construction of new pollution
control facilities, compliance has to be achieved within two years from the date of publication in
the Federal Register, or sooner if practicable.
The frequency of monitoring, recordkeeping, and reporting requirements under
Subpart E except total hydrocarbons become effective 120 days after the effective date of the
regulation. The frequency of monitoring, recordkeeping, and reporting requirements for total
hydrocarbons become effective no later than one year from the date of publication of the Part
503 regulation in the Federal Register. If compliance with the operational standard for total
hydrocarbons requires construction of new pollution control facilities, these requirements become
effective no later than two years from the date of publication of the regulation in the Federal
Register.
1.2.1.3 Permits and Direct Enforceability
The Part 503 requirements for sewage sludge incineration pertaining to the frequency of
monitoring, recordkeeping, and reporting may be implemented through a permit under the
following two conditions:
• a permit issued to a "treatment works treating domestic sewage" (TWTDS), as
defined in 40 CFR Section 122.2 and in accordance with 40 CFR Parts 122 and
124, either by EPA or by a State that has a state sludge management program
approved by EPA in accordance with 40 CFR Part 123 or 40 CFR Part 501.
• a permit issued under the Clean Air Act.
A TWTDS is required to submit a permit application in accordance with either 40 CFR Section
122.21 or an approved state program. The standards in Subpart E are enforceable directly
against any person who fires sewage sludge in a sewage sludge incinerator.
1-5
-------
1.2.1.4 Relationship to Other Regulations
The last part of Section 1.1 discussed existing statutes pertaining to sewage sludge
incineration that are referenced in the Part 503 rule. Subpart A does not include any further
stipulations regarding the relationship of the sewage sludge incineration standards to other
regulations.
1.2.13 Additional or More Stringent Requirements
On a case-by-case basis, the permitting authority (either EPA or a state with an EPA-
approved sludge management program) may impose more stringent or additional requirements
for the use or disposal of sewage sludge if necessary to protect public health and the
environment from an adverse effect of pollutants in sewage sludge. A state, a political
subdivision, or an interstate agency also can impose requirements for the use or disposal of
sewage sludge that either are more stringent than, or are in addition to, the requirements of Part
503.
1.2.1.6 Exclusions
Exclusions to the Part 503 rule can be classified according to whether they relate directly
to sewage sludge incineration or are general to all three use or disposal practices. The two
exclusions that are specific to sewage sludge incineration for which the Part 503 rule does not
apply are:
• Co-firing of sewage sludge - sewage sludge co-fired in an incinerator with other
wastes (excluding auxiliary fuel) or the incinerator in which sewage sludge and
other wastes are co-fired.
• Incinerator ash - ash generated during the firing of sewage sludge in a sewage
sludge incinerator.
1-6
-------
In addition, there are eight exclusions that apply to all three use or disposal practices:
• Treatment processes - processes used to treat domestic sewage or processes used
to treat sewage sludge prior to final use or disposal, except as provided in 503.32
and 503.33.
• Selection of a use or disposal practice - the selection of a sewage sludge use or
disposal practice. The determination of the manner in which sewage sludge is
used or disposed is a local determination.
• Sludge generated at an industrial facility - sludge generated in industrial
wastewater treatment works, including sewage sludge generated during the
treatment of industrial wastewater combined with domestic sewage. This
exemption does not apply to sewage sludge treated separately from industrial
waste at an industrial facility.
• Hazardous sewage sludge - sewage sludge determined to be hazardous in
accordance with 40 CFR Part 261.
• Sewage sludge with high PCS concentration - sewage sludge that has a
concentration of polychlorinated biphenyls (PCBs) equal to or greater than 50
milligrams per kilogram of total solids (dry weight basis).
• Grit and screenings - grit (e.g., sand, gravel, cinders, or other materials with a
high specific gravity) or screenings (e.g., relatively large materials such as rags)
generated during preliminary treatment of domestic sewage in a treatment works.
• Drinking water treatment sludge - sludge generated during the treatment of either
surface water or ground water used for drinking water.
• Commercial and industrial septage - commercial septage or industrial septage,
even if mixed with domestic septage.
1.2J.7 Requirement for a Person Who Prepares Sewage Sludge
A person who prepares sewage sludge that is either fired in a sewage sludge incinerator,
applied to the land, or placed on a surface disposal site must meet the applicable requirements
of the Part 503 rule.
1-7
-------
1.2.1.8 Sampling and Analysis
Representative samples of sewage sludge fired in a sewage sludge incinerator have to be
collected and analyzed. Samples of sewage sludge have to be analyzed for inorganic pollutants
according to the publication, Test Methods for Evaluating Solid Waste, Physical/Chemical
Methods," U.S. Environmental Protection Agency, 1982 and 1986. (For the specific reference,
see the regulation, Section 503.8(b)(4), located in Appendix A of this document.)
1.2.1 J General and Special Definitions
The following words, phrases, acronyms, and concepts apply to information provided in
this sewage sludge incineration technical support document and are defined in Appendix A,
either under the General Provisions subpart, Subpart A (503.9) or the Incineration subpart,
Subpart E (503.41).
General Definitions (503.9^
Class I sludge management facility
CWA
Dry weight basis
EPA
Permitting Authority
Person who prepares sewage sludge
Pollutant
Pollutant limit
Sewage sludge
Treatment works
Special Definitions (503.411
Air pollution control device (APCD)
Auxiliary fuel
Control efficiency
Dispersion factor
Fluidized bed furnace (FBF)
Hourly average
Incineration
Monthly average
Risk specific concentration (RSC)
Sewage sludge feed rate
Sewage sludge incinerator
Stack height
Total hydrocarbons
Wet electrostatic precipitator
Wet scrubber
1-8
-------
1.2.2 Part 503 Standard
For each sewage sludge use or disposal practice, a number of requirements must be met,
including general requirements, pollutant limits, management practices, and an operational
standard(s), as well as other requirements related to frequency of monitoring, recordkeeping, and
reporting. The information presented below relates directly to sewage sludge fired in a sewage
sludge incinerator. Section 1.3, Scope of the Sewage Sludge Incineration Technical Support
Document, outlines the sections of the document where more detailed discussions of the
Subpart E requirements are presented.
1.2 J.I General Requirements
No person is permitted to fire sewage sludge in a sewage sludge incinerator unless the
requirements of Subpart E are met.
1.22.2 Pollutant Limits
Subpart E of Part 503 regulates seven inorganic pollutants, all of which are metals. For
five of these metals—arsenic, cadmium, chromium, lead, and nickel—Subpart E requires that
site-specific limits on the concentration of the pollutants in the sewage sludge be met. The
National Emission Standards for Hazardous Air Pollutants (NESHAPs) for beryllium, if
applicable, and mercury (40 CFR Part 61) also be met.
Operational Standard
In addition to inorganic pollutants, Subpart E also regulates total hydrocarbons (THC) as
a measure of the organic pollutants emitted from a sewage sludge incinerator stack. The limit
for THC is a technology-based operational standard, not a risk-based limit, because a
methodology for developing a site-specific risk-based approach for THC is not well established.
1-9
-------
The regulation requires that the THC concentration in the exit gas be corrected to 7-percent
oxygen and for zero percent moisture, and that it be equal to or less than 100 parts per million
on a volumetric basis when measured using a flame ionization detector with a heated sampling
line. Compliance with the monthly average THC emission limit of 100 ppra is determined by
calculating the arithmetic mean of the hourly averages for the hours a sewage sludge incinerator
operates during the calendar month. An hourly average is the arithmetic mean of all THC
measurements taken during each operating hour with a minimum of two measurements taken
during the hour. The THC operational standard is based on an analysis of operating data from
several sewage sludge incinerators.
1.22.4 Management Practices
Under Subpart E, data used to determine compliance with the pollutant limits and
operational standard must be measured and recorded. The regulation requires the use of four
instruments to measure and record the following data for each sewage sludge incinerator
continuously: the THC concentration in the stack exit gas; the oxygen concentration in the stack
gas; information used to determine the moisture content in the stack gas; and combustion
temperature. The management practices specify that these instruments be installed, calibrated,
operated, and maintained as specified by the permitting authority.
Subpart E also requires that the sampling line to the THC monitor be maintained at a
temperature of 150°C or higher and that the THC monitor be calibrated using propane at least
once every 24-hour operating period; In addition, the regulation requires that the maximum
combustion temperature for a sewage sludge incinerator and the operating parameters for the air
pollution control devices (APCDs) be specified by the permitting authority and be based on
information obtained during the performance test of the sewage sludge incinerator. A final
requirement prohibits the firing of sewage sludge in a sewage sludge incinerator if it would
adversely affect a threatened or endangered species listed under Section 4 of the Endangered
Species Act or its designated critical habitat. EPA will develop guidance to carry out this
provision consistent with the Endangered Species Act.
1-10
-------
J.2JJ Other Requirements (frequency of monitoring, recordkeeping, and reporting)
Requirements concerning frequency of monitoring, recordkeeping, and reporting also
must be met when sewage sludge is fired in a sewage sludge incinerator. The frequency of
monitoring for arsenic, cadmium, chromium, lead, and nickel is set by the regulation according to
the amount of sewage sludge fired in a sewage sludge incinerator, ranging from once per year to
once per month, unless otherwise specified by the permitting authority. The regulation allows
the permitting authority to modify the frequency of monitoring for these five pollutants after the
sewage sludge is monitored for two years in accordance with Subpart E, as long as the frequency
of monitoring is at least once per year. The frequency of monitoring for beryllium and mercury
is to be specified by the permitting authority. As stated in Section 1.2.2.4, the regulation also
requires the determination of the sewage sludge feed rate and the continuous monitoring of
THC, the oxygen concentration, and information used to determine moisture content in the exit
gas, as well as maximum combustion temperature. The operating parameters for the sewage
sludge incinerator APCD(s) are to be monitored as specified by the permitting authority.
Any person who fires sewage sludge in a sewage sludge incinerator must retain certain
data for a period of five years. These data include the concentration of arsenic, cadmium,
chromium, lead, and nickel in the sewage sludge; the concentration of THC in the exit gas;
information that indicates that the NESHAPs requirements are met for beryllium, if applicable,
and mercury; and the sewage sludge feed rate. Other data obtained from the exit gas must also
be kept, including the oxygen concentration and information used to measure the moisture
content. Subpart E also requires that data be kept on certain characteristics of the sewage
sludge incinerator and APCDs, and that a calibration and maintenance log be kept for the
instruments measuring THC concentration, oxygen concentration, combustion temperatures, and
information needed to determine moisture content in the exit gas.
The reporting requirements under Subpart E pertain to Class I sludge management
facilities and treatment works with a flow rate equate to or greater than one million gallons per
day (MGD) or that serve a population of 10,000 people or greater. All treatment works
operating sewage sludge incinerators are classified as Class I sludge management facilities.
These facilities are required to report annually.
1-11
-------
1J SCOPE OF THE SEWAGE SLUDGE INCINERATION TECHNICAL SUPPORT
DOCUMENT
This document consists of nine sections, including this introduction. The next section,
Section Two, provides an overview of incineration technologies, including current furnace
technologies and APCDs. Section Three is a summary of EPA risk assessment methodology,
which is the basis for the development of limits on the concentration of five of the inorganic
pollutants in sewage sludge. In Section Four, the process by which EPA selected the eight
pollutants for regulation under -Subpart E is presented.
Section Five provides a detailed discussion of the limits for the seven inorganic pollutants
and begins with an overview explaining the different origins of the limits for all eight pollutants.
This section contains the factors EPA used to develop the risk assessment methodology and
provides several examples of calculations to better explain how the pollutant limits are derived.
The operational standard for THC is described in Section Six and includes the basis for the
standard, as well as the assessment used to judge whether the operational standard protects
public health.
Section Seven provides more detail on the management practices required under Subpart
E, while Section Eight presents the frequency of monitoring, recordkeeping, and reporting
requirements. References appear in Section Nine and 14 appendices are provided as supporting
material. Appendix A consists of the text of Part 503, Subpart A and Subpart E. Appendix B
lists the current sewage sludge incinerators subject to Part 503. Appendix C provides data on the
ratio of hexavalent chromium to total chromium measured during tests of sewage sludge
incinerator emissions. Appendix D summarizes data from nickel speciation tests at three sewage
sludge incinerators. In Appendix E, general guidelines on conducting a performance test at a
sewage sludge incinerator are provided for determining a unit's control efficiency, while
Appendix F provides emissions data for THC, carbon monoxide, and 21 organics from four
sewage sludge incinerators.
1-12
-------
Appendix G describes the statistical basis for the THC operational standard and
Appendix H explains the estimated difference between THC measurements taken with a heated
(hot) monitor and those taken with an unheated (cold) monitor. In Appendix I, a table is
provided for the molecular weights and response factors for organic compounds used to develop
the cancer potency value (q,") for THC. Appendix J presents an extensive table of calculations
that derives site-specific risk-specific concentrations and risk levels at 23 sewage sludge
incinerators listed in the National Sewage Sludge Survey.
In Appendix K, a table is provided to support the evaluation of the risk posed by the
THC standard. The table shows the weighted q,' values for over 100 carcinogenic and
noncarcinogenic organics used in development of the THC q/. Appendix L provides emissions
data for organic compounds that were used to derive the qt* for THC. The next appendix,
Appendix M, provides summary details on performance indicator parameters for APCDs.
Finally, in Appendix N, the calculation used to derive the frequency of monitoring requirement
at sewage sludge incinerators is presented.
1-13
-------
SECTION TWO
SEWAGE SLUDGE INCINERATION TECHNOLOGY
This section describes the major sewage sludge incinerator technologies currently used in
the United States. The section begins with a brief description of sewage sludge incineration
Section 2.2 discusses the design characteristics and operating conditions of the three main
incinerator furnace technologies: multiple-hearth furnaces, fluidized-bed furnaces, and electric
infrared furnaces. The final part, Section 2.3, describes a variety of air pollution control devices
(APCDs), including wet scrubbers, electrostatic precipitators, fabric filters, and afterburners, that
are installed in incinerators to further combust organic material or to remove particulates and
associated metals from the exhaust gas.
2.1 DESCRIPTION OF SEWAGE SLUDGE INCINERATION
Sewage sludge incineration is the combustion of organic matter and inorganic matter in
sewage sludge and auxiliary fuel by high temperatures in an enclosed device. Incineration is a
practice through which about 16 percent of the sewage sludge generated annually in the United
States is disposed. In 1988, EPA began to update data on sewage sludge incinerators as pan of
the National Sewage Sludge Survey (NSSS). Completed in September 1989, the survey data base
revealed that, in 1988, approximately 0.7 million dry metric tons (dmt) per year of sewage sludge
were fired in sewage sludge incinerators operated by an estimated 150 publicly owned treatment
works (POTWs) across the country, with some of these POTWs operating more than one
incinerator unit This sewage sludge quantity includes sewage sludge transferred to these
POTWs by an estimated 178 additional POTWs, but excludes sewage sludge that is co-
incinerated in municipal solid waste combustors.
2-1
-------
2.2 CURRENT FURNACE TECHNOLOGY
The three major furnace technologies currently used in the United States to fire sewage
sludge are listed below. Based on the NSSS, an estimated 207 sewage sludge incinerator units
installed in the estimated 150 onsite POTWs firing sewage sludge were of the following types
(see Appendix B for a list of sewage sludge incinerator units currently subject to Part 503):
• 156 multiple-hearth furnaces (MHFs) (75 percent of the incinerators firing sewage
sludge)
• 49 fluidized-bed furnaces (FBFs) (24 percent of the incinerators firing sewage
sludge)
• 2 electric infrared furnaces (1 percent of the incinerators firing sewage sludge)
Although three-quarters of the operating sewage sludge incinerators are estimated to be
multiple-hearths, newly installed sewage sludge incinerators are divided evenly between the
fluidized-bed and multiple-hearth varieties. Regardless of incinerator type, a main factor
involved in combustion efficiency is the water content of the sewage sludge. To increase the
efficiency of the combustion process, treatment works operators remove enough water from the
sewage sludge mechanically to bring its solids content to at least 25 to 35 percent through a
series of dewatering steps involving filtration and centrifugation systems. Most treatment works
also add a chemical conditioner to the sewage sludge, which acts as a dewatering agent. While
ferric chloride and lime were used most often in the past, operators are now finding that organic
polymers act as better dewatering agents.
By increasing the heating value of the sewage sludge, dewatering decreases the need for
auxiliary fuel and thus reduces operating costs. For typical multiple-hearth furnaces, a sewage
sludge solids content of 35 percent or greater can result in an idealized condition known as
autogenous combustion. Theoretically, combustion can become self-sustaining (or "autogenous")
so that no auxiliary fuel needs to be added. This condition can occur when sewage sludge is
burned that has a combustible solids fraction with a heating value of at least 5.54 Kcal/g, a solids
content of 30 percent or greater, and a volatile solids fraction of at least 60 to 65 percent. In
practice, however, few MHFs are operated autogenousiy. Most of these units use various
2-2
-------
quantities of auxiliary fuel. In modern fluidized-bed furnaces, an autogenous condition can be
reached at a lower solids content.
2.2.1 Multiple-Hearth Furnaces
Multiple-hearth furnaces (MHFs) were initially designed nearly a century ago for baking
mineral ores in the metals extraction industry. Since the 1930s, an air-cooled variant of the
original Herreshoff design has been used to fire sewage sludges.
2.2.1.1 Design Characteristics
MHFs are cylindrically shaped and oriented vertically. Those used to fire sewage sludge
range in size from an outer diameter of approximately 1.8 meters with a total effective hearth
area of 7.9 square meters (m2) (6-hearth furnaces) to 6.7 meters in diameter with hearth areas of
over 280 m2 (12-hearth furnaces). Hearth loading rates range from 7 to 12 wet Ib/hr/ft2 of hearth
area. This amount corresponds to furnace capacities of 0.3 tons/hr up to 18 tons/hr of wet
sewage sludge.
Figure 2-1 illustrates the overall design of a typical MHF unit. The outer shell is
constructed of steel and surrounds a series of horizontal refractory hearths. A hollow cast-iron
rotating shaft runs through the center of the hearths. A fan located at the base of the shaft
introduces cool air into the shaft and rabble arms to keep the metal from deforming under the
high temperatures.
The rabble arms are attached to the central shaft and extend above the hearths.
Attached to the rabble arras are angled plows less than a meter in length that rake the sewage
sludge in a spiral motion. The plows alternate direction between hearths. If the plows in one
hearth are angled from the outside in, those in the next hearth are then angled from the inside
out. Burners that provide auxiliary fuel are located in the sidewalls of the hearths.
2-3
-------
Figure 2-1. Cross-Section of a Multiple-Hearth Furnace
Cooling Air.
Discharge
Damper
Auxiliary
Air Ports
Rabble Arm
2 or 4 per
Hearth
Gas Flow
Clinker
Breaker
Sewage Sludge Cake,
Screenings and Grit
Sewage Sludge Inlet
Burners
Supplemental Fuel
Combustion Air
Shaft Cooling
Air Return
— Solids Flow
'— Drop Holes
Rabble Arm Drive
Ash Discharge
Shaft Cooling Air
2-4
-------
2,2.1.2 Operating Conditions
In MHFs, partially dewatered sewage sludge (25 to 35 percent solids) is fed into the
peripheiy of the top hearth. Next, the rabble arms rake the sewage sludge toward the center
shaft and break up the solid material so that a larger amount of surface area comes in contact
with heat and oxygen. The dried sewage sludge then drops through holes located near the edge
of the hearth into the second hearth-, where it is raked in the opposite direction. This process is
repeated in all subsequent hearths as the sewage sludge particles are dried and burned
continuously. The remaining dry ash is discharged through a hole at the periphery of the
bottommost hearth, where it is collected for disposal.
Ambient air is blown through the central shaft at its base and rises into the rabble arms,
cooling the shaft. A portion, or all, of this air is then recirculated from the top of the shaft back
into the lowermost hearth as preheated combustion air. Air that is not recirculated is discharged
through the top of the burner into the stack downstream of the APCDs. In addition, ambient air
is also injected directly into one of the middle hearths. The air in the combustion chamber flows
upward through the drop holes in the hearths, counter-current to the flow of the sewage sludge
particles.
The overall sewage sludge incineration process occurs within three basic zones in an
MHF. The upper hearths constitute the drying zone, where most of the moisture in the sewage
sludge is evaporated. During the drying process, the sewage sludge temperature rises from 427°C
to 760°C. Combustion occurs in the middle hearths, or combustion zone, as the temperature is
increased to about 815°C to 870°C. The combustion zone can be further subdivided into the
upper-middle hearths, where the volatile gases and solids are burned, and the lower-middle
hearths, where most of the fixed carbon is combusted. The third zone, comprising the lower-
most hearth(s), is the cooling zone. In this zone, the ash is cooled as its heat is transferred to
the incoming combustion air.
Under optimal operating conditions in an MHF, 50 to 100 percent "excess air" must be
added to ensure complete combustion of the sewage sludge. The theoretical amount of oxygen
required for complete combustion is known as the stoichiometric or theoretical oxygen. Specific
2-5
-------
stoichioraetric oxygen requirements are determined by the nature and quantity of the
combustible material to be bumed. Combustion oxygen usually is obtained from atmospheric air.
The additional oxygen (or air) available for combustion over and above the stoichioraetric
amount is called excess air. Adding excess air enhances contact between the fuel and oxygen in
the furnace and compensates for normal variations in both the organic characteristics of the
sewage sludge and the feed rate at which the sewage sludge enters the incinerator.
When the amount of oxygen (or air) is less than the stoichioraetric amount, it is called
starved air, or substoichioraetric air. Under starved-air conditions, incomplete combustion
occurs, which results in the production of carbon monoxide (CO) and products of incomplete
combustion (PICs). The formation of these combustion products is characterized by the release
of smoky emissions containing unbumed hydrocarbons and volatiles. Too much excess air, on
the other hand, results in lower temperatures, consumption of more auxiliary fuel, more
entrainraent of particulates, and lower efficiency.
The rate at which the dried sewage sludge is fed into the hearths and the sewage sludge
moisture content also can affect the performance of multiple-hearth sewage sludge incinerators.
A sharp increase in the feed rate generally causes the middle combustion zone to drop to lower
hearths, a change that can lead to a decrease in temperature within the combustion zone and
high auxiliary fuel usage. Conversely, a sudden decrease in the feed rate to the furnace can
cause excessively high temperatures in the furnace with the attendant risk of damage to the
refractory and rabble castings. The moisture content of the sewage sludge also must be kept
relatively constant for the same reasons. A sharp increase in moisture content can lead to
reduced hearth temperatures, while material that is too dry may cause overly high temperatures.
One problem resulting from excessively high temperatures in the combustion zone is the
formation of clinkers, or clumps of ash, that can break teeth and rabble arms and increase
maintenance requirements. As treatment works move from the use of ferric chloride/lime
conditioners to organic polymers, however, clinkers will become less of a problem.
For optimum performance, the temperature profile within the furnace should be
controlled by adjusting the firing rate of the burners. Ideally, only those burners located
2-6
-------
immediately above and below the combustion zone should be used, depending on the number of
hearths and the capacities of the available burners. This arrangement allows longer residence
times for the sewage sludge in the drying zone and can decrease turbulence in the upper hearths.
2.2.2 FIuidized-Bed Furnaces
In fluidized-bed furnaces (FBFs), air and sewage sludge are introduced from different
locations into a bed of sand at the base of a furnace, causing a turbulent mixing, or fluidizing
effect. The mixture of air, sewage sludge, and sand acts as a fluid in the furnace, enhancing
combustion. Fluidizing the sewage sludge has a number of advantages that help to improve the
burning atmosphere within the incinerator. First, the turbulence in the bed facilitates the
transfer of heat from the hot sand particles to the sewage sludge. Second, nearly ideal mixing is
achieved between the sewage sludge and the combustion air as a result of the greatly increased
surface area. Third, the sand provides a relatively uniform source of heat within the bed.
FBFs have been applied to a wide range of industrial processes since its initial
development in the oil-refining industry. Coal-drying and calcining operations in the phosphate
industry are two other examples of industrial applications of fluidized-bed technology. The first
fluidized-bed reactor designed specifically for firing sewage sludge was installed in 1961 in
Lynwood, Washington.
2.2 J.I Design Characteristics
Figure 2-2 depicts a cross-section of a typical FBF. Like multiple-hearth furnaces, FBFs
are cylindrical^ shaped and vertically oriented. The outer shell is constructed of steel and is
lined with refractory material. Tuyere nozzles, which blast air into the furnace, are located at the
base of the furnace within a refractory-lined arch.
There are two general FBF configurations, each based on the method used to inject the
fluidizing air into the furnace. In the "hot-windbox" design (shown in Figure 2-2), air is first
2-7
-------
Figure 2-2. Cross-Section of a Fluidized-Bed Furnace
Exhaust and Ash
Sand Feed
Thermocouple
Sewage Sludge Inlet
Rukftring Air Inlet
Pressure Tap
Sight Glass
Burner
Fuel Gun
Pressure Tap
Startup Preheat
Burner for Hot
Windbox
2-8
-------
passed through a heat exchanger, where heat is recovered from the hot flue gases. Alternatively,
in the "cold-windbox" design, ambient-temperature air is injected directly into the furnace.
The diameter of FBF units is comparable to that for MHFs, ranging from 1.8 to 7.6
meters. FBFs have sewage sludge loading rates ranging from 30 to 60 wet Ib/hr/ft2 of bed and
burning capacities ranging from 0.5 to 15 tons/hr of wet sewage sludge.
2.2.2.2 Operating Conditions
Partially dewatered sewage sludge is fed into a bed of hot sand in the lower portion of
the furnace. The sand and incoming sewage sludge are simultaneously fluidized by air injected
through the tuyere nozzles at pressures ranging from 21 to 34 kilopascals (kPa) (3 to 5 pounds
per square inch, lb/in2) while temperatures of 760°C to 925°C are maintained in the bed. Gas
residence times in the freeboard range from 2 to 5 seconds. As the sewage sludge is fired, fine
ash particles and minor amounts of sand are carried out through the top of the furnace, where
they are captured by a wet scrubbing system. (Refer to Section 2.3.1 for more information on wet
scrubbers.)
The overall combustion process in an FBF occurs in two zones. The first zone is within
the fluidized bed itself. Here, water evaporation and pyrolysis of organic materials occur almost
simultaneously, as the temperature of the sewage sludge is rapidly increased. The freeboard area
(see Figure 2-2) is considered to be the second zone, which functions essentially as an
afterburner (see Section 2.3.4), where the remaining free carbon and combustible gases are
burned.
The most noticeable impact of the improved burning atmosphere provided by an FBF, as
compared to the atmosphere provided by other furnace technologies, is the decrease in the
amount of excess air required for complete combustion of the sewage sludge. FBFs .can achieve
complete combustion of sewage sludge with 20 to 50 percent excess air, which is about half the
amount of excess air typically required for firing sewage sludge in MHFs. As a result, FBF units
generally have lower fuel requirements than MHF units.
2-9
-------
The most critical operating variable of FBF units is the rate at which the sewage sludge is
fed to the incinerator. The optimal rate of heat transfer achievable for a given quantity of sand
is reached when the sewage sludge feed rate is equal to the burning capacity of the sand bed. If
the burning capacity is exceeded because of a sewage sludge feed rate that is too high,
combustion will not be complete. Similarly, a rapid increase in either the overall furnace load or
the total sewage sludge moisture content causes the sewage sludge to coagulate into heavy
masses, eliminating the fluidized nature of the bed and halting combustion. To avoid these
negative consequences, it is important to ensure that an adequate residence time is maintained so
that the sewage sludge burns completely.
Because of excellent mixing characteristics, as well as short sewage sludge residence
times, fluidized-bed furnaces are less vulnerable than MHFs are to fluctuations in the sewage
sludge feed rate and the total moisture content of the sewage sludge fed to the furnace.
Moreover, any disruption of combustion that does occur happens almost immediately and,
therefore, can be more easily detected and corrected by the furnace operators.
2.2.3 Electric Infrared Furnaces
The electric furnace, which uses infrared radiation as a partial heat source, represents a
relatively new technological approach to sewage sludge incineration. The first such unit was put
into operation in Richardson, Texas, in 1975. Since that time, a number of installations have
been constructed.
2.2 J.I Design Characteristics
Electric furnaces, unlike the other two furnace designs, are horizontally oriented and
consist of insulated enclosures through which sewage sludge is transported on a continuous,
woven, wire-mesh conveyor belt (see Figure 2-3). The belt is made of steel alloy and can
withstand the 925°C temperatures encountered in the furnaces. The refractory lining in the
furnace is composed of ceramic felt, not brick. Because the refractory has a low capacity for
2-10
-------
Figure 2-3. Cross-Section of an Electric Infrared Furnace
Belt
Drive
Radiant Infrared
Heating Element (Typ)
Sewage Sludge Feed
Gas
Exhaust
— Roller Leveler
Rabbing Device
Cooling Air
t
• »x xx xx
Woven Wire
Continuous Belt
Cooling Air
i
Combustion
Air
u
i r
Ash Discharge
-------
holding heat, it can be started from a cold condition relatively quickly, as well as shut down
quickly.
2.2.3.2 Operating Conditions
In electric furnaces, dewatered sewage sludge is first fed into a holding tank, then into
the main unit through a feed hopper and dropped onto the conveyor belt. Here, it is leveled by
an internal roller into a layer approximately 1 inch thick, spanning the width of the belt. The
sewage sludge layer then moves under infrared heating elements, which sustain the drying and
incineration processes. The resulting ash is discharged from the end of the furnace into the ash-
handling system.
Combustion air is introduced at the end of the belt as the ash is discharged and is often
preheated with an external recuperative-exhaust heat exchanger. The air also picks up heat from
the hot burning sewage sludge as the sewage sludge and air travel counter-current to one
another.
Because the primary heat-transfer mechanism used in the infrared furnace is radiant
transfer, satisfactory combustion rates can be achieved without rabbling or plowing the sewage
sludge layer. Thus, compared to MHFs and FBFs, electric furnaces minimize fly ash generation
and more easily control paniculate emissions.
In addition, complete combustion can be achieved in the electric infrared furnace with
excess air levels as low as 10 to 20 percent. This process efficiency is attributed to several
factors. First, the furnace is designed so that uncontrolled sources of excess air are eliminated.
Second, the flow of combustion air is regulated closely and directed down the channel formed
inside the primary combustion chamber between the belt and the heating elements overhead.
Third, the addition of supplemental heat does not generate any gaseous by-products, which
ordinarily dilute the supply of combustion air. This ability to operate at low excess air levels
contributes to a further reduction in the size, complexity, and energy requirements of the exhaust
gas scrubbing equipment used with electric infrared furnaces.
2-12
-------
The electric furnace is divided into several temperature control zones. These zones are
maintained at predetermined temperatures by closed-loop control. Thermocouples sense the
temperatures and compare these temperatures with set points. The input power to the infrared
heating elements is then adjusted upward or downward, accordingly. Control temperatures range
from 760°C in the drying zones to 925°C in the combustion zones.
The flow of air for sewage sludge combustion is also controlled by a closed-loop process.
The residual oxygen content in the exhaust stream is sensed continuously and compared with a
set point value. In the event that a high-energy sewage sludge is being processed, additional
excess air can be used to limit exhaust temperatures to the 650°C to 760°C range. To
accommodate different sewage sludge feeds (e.g., sewage sludges with different moisture contents
or volatile solids contents), the throughput of the system can be controlled by adjusting the speed
of the internal conveyor belt. This adjustment is accomplished from the control panel and is
often used to adjust sewage sludge retention time.
To date, infrared furnaces have been used in smaller applications, for which the greater
operating flexibility of this type of furnace provides an advantage over traditionally larger
multiple-hearth and fiuidized-bed furnaces. Because of its ceramic-fiber blanket insulation
system, the infrared furnace is well-suited for intermittent operation. This insulation system is
not subject to the slow warm-up and cool-down thermal cycling requirements associated with the
traditional types of solid refractory materials. Start-up times of 1 to 1-V2 hours are normal, and
shutdown is accomplished by pressing a single "system stop" button. In addition, the furnace can
be left unattended until it is restarted.
2J AIR POLLUTION CONTROL DEVICES
Many different methods are used to combust organic pollutants and remove particulates
and their associated metals from sewage sludge incinerator exit gas. APCDs used for the
removal of metals include wet scrubbers, dry and wet electrostatic precipitators, and fabric filters,
while afterburners are usually installed to combust organic vapors. Table 2-1 presents a
distribution of the types of APCDs installed on each type of furnace. The data are estimates
2-13
-------
TABLE 2-1
AIR POLLUTION CONTROL DEVICES BY FURNACE TYPE
Type of Pollution Control
Baghouse or Fabric Filter
Dry Electrostatic Precipitator
Wet Electrostatic Precipitator
Dry Cyclone
Impinger
Spray Chamber
Venturi
Venturi/Impinger
Venturi/Packed Tower
Wet Cyclone
Wet Cyclone/Impinger
Afterburner with Heat Exchanger
Afterburner without Heat Exchanger
Total Number of Air Pollution
Control Devices by Furnace Type
Electric
Furnace
0
0
0
0
0
2
2
0
0
0
0
0
0
4
Fluidized
Bed
0
0
0
5
5
26
16
14
7
0
2
5
0
80
Multiple
Hearth
2
0
2
19
60
50
37
49
6
12
13
21
22
293
Total Number of Air
Pollution Control
Devices
2
0
2
24
65
78
55
63
13
12
15
26
22
377*
Source: Estimates based on the 1988 National Sewage Sludge Survey, EPA.
'The 377 air pollution control devices listed in this table are installed on an estimated 207 sewage sludge
incinerators, which are distributed by the National Sewage Sludge Survey across the following incinerator
types: 156 multiple-hearth furnaces, 49 fluidized-bed furnaces, and 2 electric furnaces.
2-14
-------
based on the 1988 National Sewage Sludge Survey. This section describes the types of APCDs
available for sewage sludge incinerators.
2-3.1 Wet Scrubbers
Historically, wet scrubbers have been the predominant APCD installed in sewage sludge
incinerators, as Table 2-1 indicates. One reason for the widespread use of wet scrubbers is that
the effluent from a treatment works provides a relatively inexpensive source of scrubber water.
Also, a system for treating the scrubber effluent is readily available in that scrubber water can be
fed back into the treatment works for solids removal. Another reason for the popularity of wet
scrubbers is that they have a long history of success in meeting pollution control standards for
paniculate matter.
The wet scrubbers listed in Table 2-1 can be grouped into three main categories: venturi
scrubbers, spray chambers, and cyclone separators. These scrubbers are most efficient at
removing larger particulates. Current air pollution control laws, however, require the removal of
finer particulates. These more stringent requirements have increased the interest in, and the
application of, electrostatic precipitator and fabric filter technologies.
The wide variety of wet scrubber controls listed in the table range from low-pressure-drop
spray chambers and wet cyclones, where the pressure drops range from 995 to 2,240 pascals (4 to
9 inches of water), to higher-pressure-drop venturi scrubbers and venturi/impingement-tray
scrubbers, with pressure drops from 2,990 to 9,955 pascals (12 to 40 inches of water). Higher
pressure drops will result in more efficient removal of paniculate matter.
2.3.1.1 Vmturillmpingement-Tray Scrubbers
Figure 2-4 presents a simplified diagram of a typical venturi/impingement-tray scrubber.
As the figure shows, hot gas that exits from the incinerator enters the precooling or quench
section of the scrubber. Spray nozzles in the quench section cool the incoming gas with
2-15
-------
Figure 2-4. Venturi/lmpingement-Tray Scrubber
Gas Exit
Effluent from
Treatment
Works
Hot Gas from
Incinerator
Mist
Eliminator
Effluent from
Treatment
Works
Flooded
Perforated
Impingement
Trays
Venturi
Scrubber
Section
Impingement-Tray
Scrubber Section
2-16
-------
treatment works effluent. The quenched gas then enters the venturi section of the control
device.
Wastewater is usually pumped into the venturi system through an inlet weir above the
quencher, entering the scrubber above the throat. This process floods the throat completely to
eliminate buildup of solids and reduce abrasion. Turbulence created by high gas velocity in the
converging throat section deflects some of the water traveling down the throat into the gas
stream.
The venturi breaks up the water into tiny particles. Paniculate matter carried along with
the gas stream collides with these water particles and the water wall. The particulates become
engulfed in the water particles and gain mass. Then, when the scrubber water and flue gas leave
the venturi section, they pass into a flooded elbow, where the decreasing velocity of the water
and gas stream allows the particulates to settle out.
Most venturi sections come equipped with variable throats. By restricting the throat area
within the venturi, the linear gas velocity is increased and, subsequently, the pressure drop is also
increased. Up to a certain point, increasing the venturi pressure drop also increases the removal
efficiency of the system. Increasing the pressure drop, however, also substantially increases the
power requirements of the incinerator fans.
At the base of the flooded elbow, the gas stream passes through a connecting duct to the
base of the impingement-tray tower, which usually contains from one to four perforated trays.
The gas stream enters the tower and passes upward through the impingement trays. The large
diameter of the tower reduces the gas velocity significantly. Effluent from the treatment works
usually enters the trays from inlet ports on opposite sides and flows across the tray. As gas
passes through each perforation in the tray, it creates a jet that bubbles up through the water
and further entrains solid particles. A mist eliminator, located at the top of the tower, reduces
the carryover of water droplets in the stack effluent gas.
2-17
-------
2.3.1.2 Spray Chamber
The spray chamber scrubber is a round or rectangular chamber into which water is
introduced by spray nozzles. There are three different spray chamber configurations by which
the water is sprayed onto the sewage sludge: concurrent flow, countercurrent flow, and cross
flow. Spray scrubbers can collect both paniculate matter and gaseous pollutants, although the
collection efficiency for fine particles is low. Figure 2-5 shows a simple countercurrent-flow spray
chamber scrubber.
In the spray-tower system, the fluid is sprayed into the enclosure by a series of nozzles
located at the top of the chamber, while the gas/particulate mixture enters the bottom of the
chamber. As the gas rises, it encounters the falling drops, which remove the particulates by
impingement. The scrubber water containing the particulates drains out the bottom of the
scrubber.
2.3.1.3 Cyclone Separator
In general, cyclone separators are effective precollectors for removing large-size
particulates from effluent gases, especially from fluidized-bed furnaces. Smaller diameter
cyclones have better removal efficiencies than those with larger diameters because they spin the
gas at a higher velocity. Cyclones are typically combined with other paniculate removal devices,
such as an electrostatic precipitator or a wet scrubber, which are more effective in eliminating
the finer particulates from the system.
A cyckrae separator is a vertical cylindrical chamber that takes advantage of the
differences in densities of the gas stream and paniculate matter. The paniculate-laden exhaust
gases enter the cyclone tangentially and swirl at high velocity. This high-rotational speed causes
centrifugal action to force the particulates to the outside of the chamber where friction with the
wall of the cyclone causes them to reduce speed and drop vertically to the discharge area at the
2-18
-------
Figure 2-5. Countercurrent-flow Spray Chamber Scrubber
Gas Exit
Liquid Sprays
G as/Part iculate
Mixture Inlet
Scrubber
Water
Drain
2-19
-------
bottom of the chamber. Figure 2-6 depicts the circular path that the paniculate matter takes
before exiting at the bottom of the cyclone (WPCF 1988).
There are basically two types of cyclone separators: large-diameter, low-efficiency
cyclones and small-diameter, high-efficiency multitube cyclones. Large cyclones have lower
collection efficiencies, especially for particle sizes less than 30 microns (fi), but have a lower
initial cost. They usually operate at a pressure drop of 250 to 750 pascals (1 to 3 inches of
water). The small-diameter multitube cyclones, however, are capable of eliminating more than
90 percent of particles greater than 10 /u. and usually operate at a pressure drop of 750 to 1,250
pascals (3 to 5 inches of water), although the cost of operating this type of system is higher.
Historically, smaller diameter systems are also more susceptible to plugging, erosion, and air
leakage.
The degree of emission control exhibited by cyclone separators depends on the
noncombustible content of the sewage sludge and the sewage sludge incinerator capacity. In
general, cyclones have a low efficiency for reducing visible emissions and odors because of their
limited capability of removing finer particulates and gaseous contaminants. However, compared
to more sophisticated devices that remove similar-sized particulates, cyclone separators require
less intensive capital investment.
232 Electrostatk Precipitators (ESPs)
Electrostatic precipitation is a process by which particles suspended in a gas are
electrically charged and separated from the gas stream under the action of an electric field. In
this process, negatively charged gas ions are formed between emitting and collecting electrodes
by applying a sufficiently high voltage to the emitting electrodes to produce a corona discharge.
Suspended paniculate matter becomes charged as a result of being bombarded by the gaseous
ions, then migrates toward the grounded collecting plates because of electrostatic forces. The
panicle charge is neutralized at the collecting electrode, where subsequent removal of the
panicles occurs.
2-20
-------
Figure 2-6. Cyclone Separator - Double Vortex Path of the Gas Stream
Particulate-Laden
Gas Stream
Zone of Most
Efficient Separation
Collected
Particulates
2-21
-------
There are two basic types of electrostatic precipitators (ESPs): dry ESPs and wet ESPs
(WESPs). Both types are used with scrubbers to increase the removal of metals bound in the
particulates emitted by sewage sludge incinerator units. Whereas scrubbers remove the larger
particulates, ESPs remove the finer material.
Because existing sewage sludge incinerators are almost exclusively equipped with wet
scrubbers, WESPs are more compatible with the wet environment created by wet scrubbers than
are dry ESPs. Dry ESPs tend to develop corrosion problems from the condensation that forms
in the system as the air passes from the wet scrubber into the dry ESP. WESPs are also favored
for existing sewage sludge incinerators because they are more compact and can be retrofitted
easily into an existing system configuration. For newly constructed sewage sludge incinerators,
however, dry ESPs might be a preferred option.
2.3J.I Dry Electrostatic Precipitators
In the United States, dry ESPs have been used widely in applications such as utility
boilers and municipal and industrial incinerators. In some European facilities, they are used on
sewage sludge incinerators. In a dry ESP, the exhaust gases pass through a large chamber, where
\
electrodes impart a negative charge to the paniculate matter in the exhaust gas stream. Parallel
with the flow of gases through the chamber are plates with a positive electrical charge, which
attract the negatively charged paniculate matter. Periodically, the buildup of paniculate matter
on the plates is removed by rapping the plates, which causes the paniculate matter to fall to the
bottom of the chamber, where it is removed (WPCF 1988).
Compared to wet scrubbers, dry ESPs generally provide higher removal efficiencies for
panicles smaller than one fi in diameter. Also, pressure and temperature drops across dry ESPs
are very small compared to those of wet scrubbers, resulting in lower energy demand. The
pressure drop across a dry ESP is typically below 249 pascals (1 inch of water), whereas wet
scrubbers often operate with pressure drops of up to 14,940 pascals (60 inches of water). Dry
ESPs generally .can withstand a maximum temperature of 370°C and often are placed
downstream of waste heat boilers, where gas temperatures of 250°C to 370°C are encountered.
2-22
-------
In dry ESPs, the participates that cling to the collecting plates are removed by periodically
tapping the plates. The collection plates typically cany a static voltage of 30 to 75 kilowatts
(kW).
2.32.2 Wet Electrostatic Precipitators
The wet electrostatic precipitator (WESP) is a variation of the dry electrostatic
precipitator design and is regarded as a type of wet scrubber system. WESPs are used with
metallurgic processes, acid-mist collection, coke-oven gas purification, and other processes where
wet conditions prevail or are desired. WESPs are now being installed more frequently in sewage
sludge incinerators in the United States because of their effectiveness in removing fine
particulates and their compatibility with existing wet scrubbers installed to remove larger
particles.
The WESP (see Figure 2-7) operates like the dry ESP in that there are electrodes to
charge the incoming gas particles and plates that are positively charged to attract those particles
(WPCF 1988). While the collection plates in dry ESPs are tapped to remove the particulates,
the plates in WESPs are flooded continuously with water to wash the particles out of the system.
Another added feature of a WESP system is that it has a preconditioning step in which inlet
water sprays in the entry section are used for cooling, gas absorption, and removal of coarse
particles.
Particle collection is achieved by first introducing evenly distributed liquid droplets to the
gas stream through sprays located above the electrostatic field sections. The sprays uniformly
cover the particulates with water, which renders all particulates the same size and facilitates the
induction of an electrical charge. After the particles are charged, they migrate to the charged
surfaces. To control the carryover of liquid droplets and mists to the stack plume, the last
section of the WESP often operates without sprays and contains baffles to collect the mist.
Because of the uniformity in size of the wetted particles, the operation of the WESP is
not influenced by changes in the resistivity of the particles, which is a problem for dry ESPs.
2-23
-------
Electric
Terminals
Gaa Inlet
Figure 2-7. Wet Electrostatic Precipitator
Gas Outlet
t
J
Tubular
VT
7 Sprays
2-24
-------
Further, since the internal components are washed continuously with liquid, buildup of sticky
particles is controlled and there is some capacity for removal of gaseous pollutants.
2.3-3 Fabric Filters
Fabric filters, or "baghouses," have achieved very high particle control efficiencies in many
applications, including metal operations, power plants, and hazardous waste incinerators. To
date, however, fabric filters have not been operated in a full-scale sewage sludge incinerator in
the United States. Only one sewage sludge incinerator, in California, is equipped with fabric
filters, and it was in the start-up phase in early 1988. While emission problems associated with
the baghouse have been reported, testing of different baghouse fabrics is still ongoing.
A baghouse consists of a collection of bags constructed from fabrics, such as nylon, wool,
or other material, hung inside a housing (see Figure 2-8). Bag materials must be selected
carefully to withstand high flue-gas temperatures and other potentially adverse conditions. The
combustion gases are drawn into the housing and pass through the bags, where the particles are
retained on the fabric material while the clean gases pass through and are exhausted through a
stack. The collected particles and cake buildup typically are removed from the bags by blasts of
air, and the removed particles (or flyash) are stored in collection hoppers. Fabric filters are
classified by the type of mechanism used to remove particles from the bags: mechanical shaker,
reverse air, and pulse jet.
The high-efficiency removal of particulates of all sizes is achieved in fabric filters through
a number of different collection mechanisms, with "inertia! impaction" being the dominant
mechanism. The fabric filter actually is most important as a support for the buildup of a dust
cake, which filters particulates carried into the cake. Inertial impaction results when high
velocity particles collide with already-deposited particles or collide directly onto the fibers.
Electrostatic forces also can play a role in collecting particles because of the difference in
electrical charge between the panicles and the filter. The effect of electrostatic charges on
paniculate removal, however, has not been demonstrated fully.
2-25
-------
Figure 2-8. Fabric Filter with Mechanical Shaking
Shaker Mechanism
Outlet Pipe
Inlet Pipe
Baffle Plate
Dusty Air Side
Clean Air Side
Filter Bags
Cell Plate
Hopper
2-26
-------
Moisture content and acid dew point are important gas composition factors that must be
monitored for effective operation of a fabric filter. The temperature of gases passing through
the fabric filter must be maintained above the acid dew point to prevent acidic moisture droplets
condensing within the filter system. Operating a fabric filter at close to the acid dew point
introduces substantial risk of corrosion, especially in localized spots close to hatches, in dead air
pockets, in hoppers, or in areas adjacent to heat sinks, such as external supports. Allowing the
operating temperature to drop below the water and/or acid dew point, either during startup or
during normal operation, will usually cause blinding of the bags.
Fabric filters often are not used alone to filter incinerator flue gas because acid gases
attack the fabric and sticky particles "blind" the fabric. Such a condition results when the filter
bags become saturated with moisture, allowing a cake to build up so heavily that it cannot be
removed. Eventually, the system becomes plugged and air flow is halted. Acids or alkaline
materials can also weaken fabric filters and shorten their useful lives, as can trace components,
such as fluorine. In addition, baghouse fires have resulted when sparks have been entrained into
the flue. ESPs and wet scrubbers have been somewhat less affected by these problems and have
generally been used instead of fabric filters.
Technologies are now available for fabric filters, however, that address these problems
successfully. These new technologies are equipped with upstream acid gas scrubbers, which
alleviate the effect of acid gas on the fabric and sorbent accumulation on fabric materials. Thus,
fabric filters are becoming a more attractive choice for paniculate control, as well as for control
of other pollutants. Even so, for existing sewage sludge incinerators, of which almost all are
equipped with wet scrubbers, WESPs are more compatible with the wet scrubber environment
than are fabric filters.
Fabric filters combined with either a wet/dry or a dry scrubbing system have
demonstrated very high metals collection efficiencies when installed on municipal solid waste
combustors. Dry scrubber/fabric filter systems also are being used successfully on a number of
hazardous waste incinerators in Europe and the United States. These systems can probably be
applied to sewage sludge incinerators if very high (greater than 99 percent) metals removal
efficiencies are needed to reduce incinerator metals emissions to acceptable risk levels.
2-27
-------
Currently, a fluidized-bed furnace system with a dry scrubber/baghouse system is being built in
the United States.
2.3.4 Afterburners
Afterburners are simple combustors that use oxidation to combust organic compounds
not combusted in the primary incinerator chamber. The reaction, when complete, produces the
nontoxic effluent gases of carbon dioxide, nitrogen, and water vapor. The three types of
afterburners described in this section are direct-flame, thermal, and catalytic. Direct-Same and
thermal afterburners are similar in that they both raise gas temperature for more complete
combustion of organic vapors but differ in the method used to increase the gas temperature. In
a direct-flame afterburner, a high percentage of the vapors pass directly through the flame. By
contrast, in a thermal unit, the vapors remain in a high-temperature, oxidizing atmosphere long
enough for oxidation reactions to take place. The third afterburner type (catalytic) incorporates
a catalytic surface to accelerate the oxidation reactions.
Afterburners are fired by either gaseous or liquid fuels. Gaseous fuels permit firing in
multiple-jet (or distributed) burners that expose more matter to the fuel, resulting in more
effective breakdown of the orgamcs. Oil firing, on the other hand, has the disadvantage of
producing sulfur oxides (from sulfur in the oil), and often results in higher nitrogen oxide
emissions than gaseous fuels.
2.3.4.1 Direct-Flam* Afterburners
Direct-flame afterburners require significant amounts of fuel to operate, resulting in high
fuel costs. To improve the economic efficiency of direct-flame afterburners, these units are often
operated with a heat-recovery system. Heat is recovered by generating process steam in a waste-
heat boiler, which recovers most of the energy produced in the combustion process. Another
way to reduce fuel use in direct-flame afterburners is to use a recuperator, or heat-exchange
2-28
-------
system, that heats the incoming gas stream with the high-temperature exit gas. Figure 2-9 is a
simple sketch of a typical direct-flame afterburner.
2.3.4.2 Thermal Afterburners
To ensure destruction of organic vapors, thermal afterburners expose the vapors to a
high-temperature, oxidizing atmosphere. Temperatures ranging from 650°C to 1,300°C generally
are required for successful operation of these devices. Usually, organic compound levels can be
reduced satisfactorily at temperatures of 760°C, but higher temperatures may be required to
oxidize carbon monoxide. The following temperatures are often used as oxidation guidelines:
• Hydrocarbons—500° to 650°C (930 to 1,200°F)
• Carbon monoxide—650° to 800°C (1,200 to 1,472°F)
The residence time in most operating thermal afterburner systems is dictated primarily by
the chemical kinetic properties of the gases. To ensure good mixing, thermal afterburners are
operated at high-velocity gas flows. Gas velocities in thermal afterburners range from 7.6 to 15.2
m/sec. Depending on the type of pollutant in the gas stream, residence times ranging from 0.2
to 6.0 seconds are required for complete combustion.
2.3.4.3 Catalytic Afterburners
Catalytic afterburners usually use noble metals, such as platinum and palladium, as the
catalytic agents to destroy gaseous wastes containing low concentrations of combustible materials
with air. (Catalysts are materials that promote a chemical reaction without taking part in it. The
catalyst does not change, and is not used up. It is, however, subject to contamination and loss of
its effectiveness.)
Catalytic afterburners can combust gaseous wastes at relatively low temperatures while
achieving high destruction efficiencies, thus minimizing the need for fuel. Most of the
2-29
-------
Rgure 2-9. Direct-Rame Afterburner
Auxiliary
Fuel
Afterburner
Chamber
Incinerator
Gas
2-30
-------
combustion occurs while the gas is flowing through the catalyst bed, which operates at ma:\:murr.
temperatures of 810°C to 870°C. Generally, catalytic afterburners are installed when waste
combustion gases contain low hydrocarbon levels. If the waste gas contains a heating value
sufficiently high to cause concern about destroying the catalytic agents by overheating, the gas
may be diluted by atmospheric air to ensure an operating temperature within the temperature
limits of the catalyst.
The residence time for catalytic oxidation typically is about 1 second. Because the
combustion reaction occurs on the surface of the catalyst, the catalyst must be physically
supported in the hot waste-gas stream by a geometrically configured structure that enables the
greatest amount of catalytic surface area to be exposed to the waste gas.
2-31
-------
SECTION THREE
RISK ASSESSMENT METHODOLOGY
This chapter discusses current EPA methods and established Agency policy for
performing a risk assessment. This process was outlined originally by the National Academy of
Sciences (NAS, 1983) and was established as final Risk Assessment Guidelines in the Federal
Register (U.S. EPA, 1986b). Five types of guidelines were issued:
• Guidelines for Carcinogen Assessment
• Guidelines for Estimating Exposure
• Guidelines for Mutagenicity Risk Assessment
• Guidelines for Health Effects of Suspect Developmental Toxicants
• Guidelines for Health Risk Assessment of Chemical Mixtures.
The Risk Assessment Methodology consists of four distinct steps: hazard identification,
dose-response evaluation, exposure evaluation, and characterization of risks.
3.1 HAZARD IDENTIFICATION
The primary purposes of hazard identification are to determine whether the chemical
poses a hazard and whether there is sufficient information to perform a quantitative risk
assessment. Hazard identification consists of gathering and evaluating all relevant data that help
determine whether a chemical poses a specific hazard, then qualitatively evaluating those data on
the basis of the type of health effect produced, the conditions of exposure, and the metabolic
processes that govern chemical behavior within the body. Thus, the goals of hazard identification
are to determine whether it is appropriate scientifically to infer that effects observed under one
set of conditions (e.g., in experimental animals) are likely to occur in other settings (e.g., in
human beings), and whether data are adequate to support a quantitative risk assessment.
3-1
-------
The first step in hazard identification is gathering information on the toxic properties of
chemical substances. The principal methods are animal studies and controlled epidemiological
investigations of exposed human populations.
The use of animal toricity studies is based on the longstanding assumption that effects in
human beings can be inferred from effects in animals. There are three categories of animal
bioassays: acute exposure tests, subchronic tests, and chronic tests. The usual starting point for
such investigations is the study of acute toxicity in experimental animals. Acute exposure tests
expose animals to high doses for short periods of time, usually 24 hours or less. The most
common measure of acute toxicity is the lethal dose (LD50), the average dose level that is lethal
to 50 percent of the test animals. LDj,, refers to oral doses. LCg, designates the inhalation dose
at which 50 percent of the animals exposed died. LCX is also used for aquatic toxicity tests and
refers to the concentration of the test substance in the water that results in 50 percent mortality
in the test species. Substances exhibiting a low LDg, (e.g., for sodium cyanide, 6.4 mg/kg) are
more acutely toxic than those with higher values (e.g., for sodium chloride, 3,000 mg/kg)
(NIOSH, 1979).
Subchronic tests for chemicals involve repeated exposures of test animals for 5 to 90 days,
depending on the animal, by exposure routes corresponding to human exposures. These tests are
used to determine the No Observed Adverse Effect Level (NOAEL), the Lowest Observed
Adverse Effect Level (LOAEL), and the Maximum Tolerated Dose (MTD). The MTD is the
largest dose a test animal can receive for most of its lifetime without demonstrating adverse
effects other than cancer. In studies of chronic effects of chemicals, test animals receive daily
doses of the test agent for approximately 2 to 3 years. The doses are lower than those used in
acute and subchronic studies, and the number of animals is larger because these tests are trying
to detect effects that will be observed in only a small percentage of animals.
The second method of evaluating health effects uses epidemiology—the study of patterns
of disease in human populations and the factors that influence these patterns. In general,
scientists view well-conducted epidemiological studies as the most valuable information from
which to draw inferences about human health risks. Unlike the other approaches used to
evaluate health effects, epidemiological methods evaluate the direct effects of hazardous
substances on human beings. These studies also help identify human health hazards without
3-2
-------
requiring prior knowledge of disease causation, and they complement the information gained
from animal studies.
Epidemiological studies compare the health status of a group of persons who have been
exposed to a suspected causal agent with that of a comparable nonexposed group. Most
epidemiological studies are either case-control studies or cohort studies. In case-control studies,
a group of individuals with specific disease is identified (cases) and compared with individuals
not having the disease (controls) in an attempt to ascertain commonalities in exposures they may
have experienced in the past. Cohort studies start with a group of people (a cohort) considered
free of the disease under investigation. The health status of the cohort known to have a
common exposure is examined over time to determine whether any specific condition or cause of
death occurs more frequently than might be expected from other causes.
Epidemiological studies are well suited to situations in which exposure to the risk agent is
relatively high; the adverse health effects are unusual (e.g., rare forms of cancer); the symptoms
of exposure are known; the exposed population is clearly defined; the link between the causal
risk agent and adverse effects in the affected population is direct and clear, the risk agent is
present in the bodies of the affected population; and high levels of the risk agent are present in
the environment.
The next step in hazard identification is to combine the pertinent data to ascertain the
degree of hazard associated with each chemical. In general, EPA uses different approaches for
qualitatively assessing the risk or hazard associated with carcinogenic versus noncarcinogenic
effects. For noncarcinogenic health effects (e.g., systemic toxicity), the Agency's hazard
identification/weight-of-evidence determination has not been formalized and is based only on a
qualitative assessment
EPA's guidelines for carcinogenic risk assessment (U.S. EPA, 1986a) group all human
and animal data reviewed into the following categories based on degree of evidence of
carcinogenicity:
• Sufficient evidence
• Limited evidence (e.g., in animals, an increased incidence of benign tumors only)
3-3
-------
• Inadequate evidence
• No data available
• No evidence of carcinogenicity.
Human and animal evidence of carcinogenicity in these categories is combined into the
following weight-of-evidence classification scheme:
• Group A—Human carcinogen
• Group B—Probable human carcinogen
Bl—Higher degree of evidence
B2—Lower degree of evidence
• Group C—Possible human carcinogen
• Group D—Not classifiable as to human carcinogenicity
• Group E—Evidence of noncarcinogenicity
Group B, probable human carcinogens, is usually divided into two subgroups: Bl.
chemicals for which there is some limited evidence of carcinogenicity from epidemiology studies;
and B2, chemicals for which there is sufficient evidence from animal studies but inadequate
evidence from epidemiology studies. EPA treats chemicals classified in categories A and B as
suitable for quantitative risk assessment. Chemicals classified as Category C receive varying
treatment with respect to dose-response assessment, and they are determined on a case-by-case
basis. Chemicals in Groups D and E do not have sufficient evidence to support a quantitative
dose-response assessment.
The following factors are evaluated by judging the relevance of the data for a particular
chemical:
• Quality of data.
• Resolving power of the studies (significance of the studies as a function of the
number of animals or subjects).
• Relevance of route and timing of exposure.
• Appropriateness of dose selection.
3-4
-------
• Replication of effects.
• Number of species examined.
• Availability of human epidemiologjc study data.
• Relevance of tumors observed (e.g., forestomach, mouse liver, male rat kidney)
Although the information gathered during the course of identifying each chemical hazard
is not used to estimate risk quantitatively, hazard identification enables researchers to
characterize the body of scientific data in such a way that two questions can be answered:
(1) Is a chemical a hazard? and (2) Is a quantitative assessment appropriate? The following two
sections discuss how such quantitative assessments are conducted.
3.2 DOSE-RESPONSE EVALUATION
Estimating the dose-response relationships for the chemical under review is the second
step in the risk assessment methodology. Evaluating dose-response data involves quantitatively
characterizing the connection between exposure to a chemical (measured in terms of quantity
and duration) and the extent of toxic injury or disease. Most dose-response relationships are
estimated based on results of animal studies, because even good epidemiological studies rarely
i
have reliable information on exposure. Therefore, this discussion focuses primarily on dose-
response evaluations based on animal data.
There are two general approaches to dose-response evaluation, depending on whether the
health effects are based on threshold or nonthreshold characteristics of the chemical. In this
context, thresholds refer to exposure levels below which no adverse health effects are assumed to
occur. For effects that involve altering genetic material (including carcinogenicity and
mutagenicity), die Agency's position is that effects may take place at very low doses, and
therefore, they are modeled with no thresholds. For most other biological effects, it is usually
(but not always) assumed that "threshold" levels exist.
For nonthreshold effects, the key assumption is that the dose-response curve for such
chemicals exhibiting these effects in the human population achieves zero risk only at zero dose.
A mathematical model is used to extrapolate response data from doses in the observed
3-5
-------
(experimental) range to response estimates in the low-dose ranges. Scientists have developed
several mathematical models to estimate low-dose risks from high-dose experimental risks. Each
model is based on general theories of carcinogenesis rather than on data for specific chemicals.
The choice of extrapolation model can have a significant impact on the dose-response estimate.
For this reason, the Agency's cancer assessment guidelines recommend the use of the multistage
model, which yields estimates of risk'that are conservative, representing a plausible upper limit of
risk. With this approach, the estimate of risk is not likely to be lower than the true risk (U.S.
EPA, 1986a).
The potency value, referred to by the Carcinogenic Assessment Group as qt*, is the
quantitative expression derived from the linearized multistage model that gives a plausible upper-
bound estimate to the slope of the dose-response curve in the low-dose range. The q,* is
expressed in terms of risk-per-dose, and has units of (rag/kg* day)"1. These values should be used
only in dose ranges for which the statistical dose-response extrapolation is appropriate. EPA's
qt* values can be found in the Integrated Risk Information System (IRIS), accessible through the
National Library of Medicine.
Dose-response relationships are assumed to exhibit threshold effects for systemic
toxicants or other compounds exhibiting noncarcinogenic, nonmutagenic health effects. Dose-
response evaluations for substances exhibiting threshold responses involve calculating what is
known as the Reference Dose (oral exposure) or Reference Concentration (inhalation exposure),
abbreviated to RfD and RfC, respectively. This measure is used as a threshold level for critical
noncancer effects below which a significant risk of adverse effects is not expected. The RfDs and
RfCs developed by EPA can be found in IRIS.
The RfD/RfC methodology uses four experimental levels: No Observed Effect Level
(NOEL), No Observed Adverse Effect Level (NOAEL), Lowest Observed Effect Level (LOEL),
or Lowest Observed Adverse Effect Level (LOAEL). Each level is stated in mg/kg»day, and all
the levels are derived from laboratory animal and/or human epidemiology data. When the
appropriate level is determined, it is then divided by an appropriate uncertainty (safety) factor.
The magnitude of safety factors varies according to the nature and quality of the data from
which the NOAEL or LOAEL is derived. The safety factors, ranging from 1 to 10,000, are used
to extrapolate from acute to chronic effects, interspecies sensitivity, and variation in sensitivity in
human populations. They are also used to extrapolate from a LOAEL to a NOAEL. Ideally, for
3-6
-------
all threshold effects, a set of route-specific and effect-specific thresholds should be developed. If
information is available for only one route of exposure, this value is used in a route-to-route
extrapolation to estimate the appropriate threshold. Once these values are derived, the next step
is to estimate actual human (or animal) exposure.
3 J EXPOSURE EVALUATION
Exposure evaluation uses data concerning the nature and size of the population exposed
to a substance, the route of exposure (i.e., oral, inhalation, dermal), the extent of exposure
(concentration times time), and the circumstances of exposure.
There are two ways of estimating environmental concentrations:
• Directly measuring levels of chemicals (monitoring)
• Using mathematical models to predict concentrations (modeling)
In addition, an analysis of population exposure is necessary.
3.3.1 Monitoring
Monitoring involves collecting and analyzing environmental samples. These data provide
the most accurate information about exposure. The two kinds of exposure monitoring are
personal monitoring and ambient (or site and location) monitoring.
Most exposure assessments are complicated by the fact that human beings move from
place to place and are therefore exposed to different risk agents throughout the day. Some
exposure assessments attempt to compensate for this variability by personal monitoring. Personal
monitoring uses one or more techniques to measure the actual concentrations of hazardous
substances to which individuals are exposed. One technique is sampling air and water. The
amount of time spent in various microenvironments (i.e., home, car, or office), may be combined
3-7
-------
with data on environmental concentrations of risk agents in those raicroenvironraents to estimate
exposure.
Personal monitoring may also include the sampling of human body fluids (e.g., blood,
urine, or semen). This type of monitoring is often referred to as biological monitoring or
biomonitoring. Biological markers (also called biomarkers) can be classified as markers of
exposure, of effect, and of susceptibility. Biological markers of exposure measure exposure either
to the exogenous material, its metabolite(s), or to the interaction of the xenobiotic agent with the
target cell within an organism. An example of a biomarker of exposure is lead concentration in
blood. In contrast, biologic markers of effect measure some biochemical, physiologic, or other
alteration within the organism that points to impaired health. (Sometimes the terra
biomonitoring is also used to refer to the regular sampling of animals, plants, or microorganisms
in an ecosystem to determine the presence and accumulation of pollutants, as well as their effects
on ecosystem components.)
Ambient monitoring (or site or location monitoring) involves collecting samples from the
air, water, soil, or sediments at fixed locations, then analyzing the samples to determine
environmental concentrations of hazardous substances at the locations. Exposures can be further
evaluated by modeling the fate and transport of the pollutants.
332 Modeling
Measurements are a direct and preferred source of information for exposure analysis.
However, such measurements are expensive and are often limited geographically. The best use
of such data is to calibrate mathematical models that can be more widely applied. Estimating
concentrations using mathematical models must account not only for physical and chemical
properties related to fate and transport, but must also document mathematical properties (e.g.,
analytical integration vs. statistical approach), spatial properties (e.g., one, two, or three
dimensions), and time properties (steady-state vs. nonsteady-state).
Hundreds of models for fate, transport, and dispersion from the source are available for
all media. Models can be divided into five general types by media: atmospheric models, surface-
water models, ground-water and unsaturated-zone models, multimedia models, and food-chain
3-8
-------
models. These five types of models are primarily applicable to chemicals or to radioactive
materials associated with dusts and other panicles.
Selecting a model for a given situation depends on the following criteria: capability of
the model to account for important transport, transformation, and transfer mechanisms; fit of the
model to site-specific and substance-specific parameters; data requirements of the model,
compared to availability and reliability of off-site information; and the form and content of the
model output that allow it to address important questions regarding human exposures.
To the extent possible, selection of the appropriate fate and transport model should
follow guidelines specified for particular media where available; for example, the Guidelines on
Air Quality Models (U.S. EPA, 1986c).
3.3.3 Population Analysis
Population analysis involves describing the size and characteristics (e.g., age/sex
distribution), location (e.g., workplace), and habits (e.g., food consumption) of potentially
exposed human and nonhuman populations. Census and other survey data often are useful in
identifying and describing populations exposed to a chemical.
Integrated exposure analysis involves calculating exposure levels, along with describing the
exposed populations. An integrated exposure analysis quantifies the contact of an exposed
population to each chemical under investigation via all routes of exposure and all pathways from
the sources to the exposed individuals. Finally, uncertainty should be described and quantified to
the extent possible.
3.4 RISK CHARACTERIZATION
This final step in the risk assessment methodology involves integrating the information
developed in hazard identification, dose-response assessment, and exposure assessment to derive
quantitative estimates of risk. Qualitative information should also accompany the numerical risk
estimates, including a discussion of uncertainties, limitations, and assumptions. It is useful to
3-9
-------
distinguish methods used for chemicals exhibiting threshold effects (i.e., most noncarcinogens)
from those believed to lack a response threshold (i.e., carcinogens).
For carcinogens, individual risks are generally represented as the probability that an
individual will contract cancer in a lifetime as a result of exposure to a particular chemical or
group of chemicals. Population risks are usually estimated based on expected or average
exposure scenarios (unless information on distributions of exposure is available). The number of
persons above a certain risk level, such as 10"4, or above a series of risk levels (10~5, 10"4, etc.), is
another useful descriptor of population risks. Thus, individual risks also may be presented using
cumulative frequency distributions, where the total number of people exceeding a given risk level
is plotted against the individual risk level.
For noncarcinogens, dose-response data above the threshold are usually lacking.
Therefore, risks are characterized by comparing the dose or concentration to the threshold level,
using a ratio in which the dose is placed in the numerator and the threshold in the denominator.
Aggregate population risks for noncarcinogens can be characterized by the number of people
exposed above the RfD or RfC. Recall that the hazard identification step for threshold
chemicals is addressed qualitatively because no formal Agency weight-of-evidence evaluation is
currently available for noncarcinogenic chemicals. The same approach can be used to assess
both acute and chronic hazards. For assessing acute effects, the toxicity data and exposure
assessment methods must account for the appropriate duration of exposure.
3-10
-------
SECTION FOUR
POLLUTANTS OF CONCERN FOR
SEWAGE SLUDGE INCINERATION
The number of pollutants regulated under Part 503 depends on the sewage sludge use or
disposal practice. Subpart E regulates eight pollutants for sewage sludge fired in a sewage sludge
incinerator—arsenic, beryllium, cadmium, chromium, lead, mercury, nickel, and total
hydrocarbons (THC). This section describes how the Agency selected these eight pollutants for
regulation, and discusses the data bases used to collect information about the pollutants. Since
the selection of pollutants to be regulated under all sewage sludge use or disposal practices
occurred concurrently, this section discusses the selection process broadly and, where
appropriate, focuses on the pollutants found in sewage sludge fired in a sewage sludge
incinerator. Those interested in greater detail on the pollutant selection process are encouraged
to refer to the following two documents: The Record of Proceedings on the OWRS Municipal
Sewage Sludge Committees, and Summary of the Environmental Profiles and Hazard Indices for
Constituents of Municipal Sludge (U.S. EPA, 1983a, 1985h).
4.1 INITIAL LIST OF POLLUTANTS
In the Spring of 1984, EPA enlisted the assistance of federal, state, academic, and private
sector experts to determine which pollutants, likely to be found in sewage sludge, should be
examined closely as possible candidates for developing numeric limits. These experts screened a
list of approximately 200 pollutants in sewage sludge that, when sewage sludge is used or
disposed, could cause adverse human health or environmental effects. Many of the pollutants
placed on the initial list for consideration came from the Clean Water Act's list of Priority
Pollutants and Appendix VIE of the Resource Conservation and Recovery Act. The experts
were requested to revise the list, adding or deleting pollutants.
4-1
-------
The test for inclusion or exclusion of pollutants involved a qualitative determination of
the potential risk to human health and the environment when sewage sludge containing a
particular pollutant was applied to the land, placed on a surface disposal site, incinerated, or
disposed in the ocean.1 The Agency also requested that the experts identify the most likely
pathway by which a pollutant could travel to reach target organisms, whether human, plant, or
wild or domestic animals. For sewage sludge fired in a sewage sludge incinerator, inhalation was
chosen as the most likely route of exposure.
Based on the qualitative assessments of each of the approximately 200 initial pollutants,
the committee of experts recommended that the Agency gather additional environmental
information on approximately 50 pollutants (see Table 4-1). For each pollutant, EPA developed
an "environmental profile" and a "hazard index" to evaluate further and rank the degree of
hazard each of the 50 pollutants posed. The environmental profiles consisted of data on toxicity,
occurrence, and fate and effects of each pollutant. The profiles also contained a series of indices
for evaluating the pollutant's hazard relative to the major exposure pathway(s) for each use or
disposal practice (U.S. EPA 1985a-h). The other 150 pollutants were not included on the list
because the committee judged them not likely to cause adverse human health or environmental
effects if used or disposed properly.
Of the 50 pollutants selected for further consideration, 29 were considered a potential
risk if sewage sludge was fired in a sewage sludge incinerator. Not every pollutant was
considered a potential risk under each use or disposal practice because different use or disposal
practices may result in different exposure levels for the same pollutant. For example, although
iron was considered a possible risk to human health and the environment when sewage sludge is
applied to land, this pollutant was not considered very likely to result in a significant risk if the
sewage sludge was fired in a sewage sludge incinerator or placed on a surface disposal site.
1The final Part 503 rule regulates three use or disposal practices: land application, surface
disposal, and incineration (see Appendix A for definitions). Included in the land application
category is the distribution and marketing of sewage sludge (which was a separate category in the
Part 503 proposal), and included in the surface disposal category is the disposal of sewage sludge
in a surface disposal site or sewage sludge-only landfill, which also was a separate category in the
proposal.
4-2
-------
TABLE 4-1
POLLUTANTS SELECTED FOR
ENVIRONMENTAL PROFILES/HAZARD INDICES*
Pollutants
Aldrin/Dieldrin
Arsenic
Benzene
Benzo(a)anthracene
Benzo(a)pyrene
Beryllium
Bis(2-ethylhexyl) phthalate
Cadmium
Carbon tetrachloride
Chlordane
Chlorinated dibenzodioxins
Chlorinated dibenzofurans
Chloroform
Chromium
Cobalt
Copper
Cyanide
DDT/DDD/DDE
2,4-Dichlorophenoxy-acetic acid
Fluoride
Heptachlor
Hexachlorobenzene
Hexachlorobutadiene
Land
Application
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Surface Disposal Site
(formerly Landfill)
X
X
X
X
X
X
X
X
X
X
X
X
Incineration
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
4-3
-------
TABLE 4-1 (continued)
Pollutants
Iron
Lead
Lindane
Malathion
Mercury
Methylene bis (2-chloroaniline)
Methylene chloride
Methylethyl ketone
Molybdenum
N-nitrosodimethylaraine
Nickel
PCBs
Pentachlorophenol
Phenanthrene
Phenol
Selenium
Tetrachloroethylene
Toxaphene
Trichloroethylene
Tricresyl phosphate
Vinyl chloride
Zinc
Land
Application
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Surface Disposal Site
(formerly Landfill)
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Incineration
X
X
X
X
X
X
X
X
X
X
X
X
'Excludes pollutants selected for environmental profiles and hazard indices for the ocean disposal
of sewage sludge.
4-4
-------
4.2 ENVIRONMENTAL PROFILES
During 1984 and 1985, the Agency collected data and information from published
scientific reports on the list of 50 pollutants of concern, including toxicity and persistence
information and information on the pathways by which the pollutants travel through the
environment to a receptor organism {plant, animal, or human); the mechanisms that transport or
bind the pollutants; and the effects of the pollutants on the target organism. EPA also analyzed
data on the relative frequencies and concentrations of sewage sludge pollutants as part of an
Agency study of 45 POTWs in 40 cities. The study was officially called the "Fate of Priority
Pollutants in Publicly Owned Treatment Works," but was better known as the "40 City Study"
(U.S. EPA, 1982). The 40 City Study contained data on the concentrations of 40 pollutants in
the sewage sludge (12 metals, 6 base neutral organic compounds, 6 volatile organic compounds, 9
pesticides, and 7 polychlorinated biphenyls [PCBs]).
EPA used the data collected on the 50 pollutants to assess the likelihood of each
pollutant to affect human health or the environment adversely. For this analysis, EPA relied on
rudimentary risk assessments to predict at what concentration a pollutant would occur in surface
or ground water, soil, air, or food. EPA then compared the predicted pollutant concentration
with an Agency human health criterion to determine whether, at that concentration, the pollutant
could be expected to have an adverse effect.
For carcinogens, if the calculated risk using the predicted concentration was lower than
an allowable cancer risk level of 1 x 10"* (1 person in 1,000,000),2 the pollutant was not
considered to have an adverse effect. For noncarcinogens, adverse impact hinged on whether the
pollutant concentration exceeded an existing standard, such as the National Emission Standard
for Hazardous Air Pollutants (NESHAPs) for beryllium and mercury, in the case of sewage
2In the initial phase of the pollutant selection process, EPA chose the 1 x 10"6 risk level as
being protective of human health for a most sensitive individual exposed under a hypothetical
worst-case scenario. As discussed in Section 5.3, later EPA analyses for the proposed Part 503
rule used a 1 x 10"s risk level for sewage sludge incineration and a 1 x 10"* risk level for the other
use or disposal practices, while the final rule uses a risk level of 1 x 10~* for all use or disposal
practices. The 1 x 10"6 risk level used at the outset of the pollutant selection process was more
inclusive of the number of pollutants selected for further, more extensive analysis.
4-5
-------
sludge fired in a sewage sludge incinerator. To determine the human health impact of the
pollutants of concern, EPA assumed worst-case conditions that would maximize the pollutant
exposure.
The Agency used the rudimentary risk assessments to score and rank each pollutant,
screening out those pollutants not expected to have an adverse human health impact before
proceeding with more thorough, detailed modeling for pollutants considered to be of concern.
EPA excluded two categories of pollutants from further evaluation. First, EPA excluded
pollutants that, when compared to the "hazard index," presented no risk to human health at the
highest concentration found in the 40 City Study or in other available data bases for each
particular use or disposal practice. Hazard indices were developed for each pollutant and for
each use or disposal practice and used to compare a pollutant's risk to the 1 x 10~* risk level for
carcinogens or to a threshold level index for noncarcinogens. Table 4-2 identifies the pollutants
excluded under this category by use or disposal practice. Some of the pollutants excluded for
one use or disposal practice were determined to present a risk for a different use or disposal
practice. For example, even though copper was found to present no risk for sewage sludge fired
in a sewage sludge incinerator, it is regulated under the Part 503 regulation for land application.
The second category of pollutants deferred from consideration were those for which no EPA
human health criteria were available or for which there were insufficient data to conduct a risk
assessment (see Table 4-3).
Of the 29 pollutants for which environmental profiles and hazard indices were developed,
11 were dropped from further consideration and are found in either Table 4-2 or Table 4-3. Of
the 18 remaining pollutants, 7 are being regulated as individual pollutants under Part 503, while
the other 11 are being regulated under Part 503 under the category of total hydrocarbons (THC)
(see Section 6.1). The THC category covers other hydrocarbon compounds as well, including
five found either in Table 4-2 or Table 4-3. Table 4-4 lists the 16 organic compounds from the
list of 29 pollutants for which environmental profiles and hazard indices were developed that are
being regulated under the Part 503 incineration regulation through the operational standard on
THC.
4-6
-------
TABLE 4-2
POLLUTANTS EVALUATED AND FOUND
NOT TO CAUSE AN ADVERSE EFFECT ON HUMAN HEALTH
FOR SEWAGE SLUDGE FIRED IN A SEWAGE SLUDGE INCINERATOR
• Benzene • Methylene chloride
• Copper ' • Selenium
• Heptachlor • Tetrachloroethylene
• Mercury* • Zinc
'Regulated under Part 503 through the National Emission Standards for
Hazardous Air Pollutants
4-7
-------
TABLE 4-3
POLLUTANTS DEFERRED BECAUSE OF INSUFFICIENT DATA
TO CONDUCT A RISK ASSESSMENT
FOR SEWAGE SLUDGE FIRED IN A SEWAGE SLUDGE INCINERATOR
• Benzo(a)anthracene
• Phenanthrene
• Vinyl chloride
4-8
-------
TABLE 4-4
POLLUTANTS SELECTED FOR ENVIRONMENTAL PROFILES/
HAZARD INDICES THAT ARE REGULATED UNDER PART 503 THROUGH
THE TOTAL HYDROCARBONS STANDARD
• Aldrin/Dieldrin . • Chloroform
• Benzene • DDT/DDD/DDE
• Benzo(a)pyrene • Heptachlor
• Bis(2-ethylhexyl) phthalate • Lindane
• Carbon tetrachloride • Methylene chloride
• Chlordane • PCBs
• Chlorinated dibenzodioxins • Tetrachloroethylene
• Chlorinated dibenzofurans • Toxaphene
4-9
-------
Listed in Table 4-5 are the eight pollutants regulated under the Pan 503 rule when
sewage sludge is fired in a sewage sludge incinerator. While EPA believed that the 40 City Study
data were the appropriate data on which to base the February 6, 1989, proposed Part 503
regulation, the Agency concluded that the data needed to be replaced or, at a minimum,
supplemented to support the final regulation. EPA therefore undertook the National Sewage
Sludge Survey (NSSS)3 to obtain a current and reliable data base for evaluating the impacts of
the final Part 503 rule. Based on the NSSS, the pollutants of concern for sewage sludge
incineration regulated in the final rule did not change from the pollutants of concern identified
for the proposed regulation using data from the 40 City Study.
3The National Sewage Sludge Survey data collection effort began in August 1988 and was
completed in September 1989. EPA collected sewage sludge samples at 180 publicly owned
treatment works (POTWs) with either secondary or advanced treatment processes and analyzed
them for more than 400 pollutants. In addition, through the use of detailed questionnaires, the
survey collected information on sewage sludge use or disposal practices from 475 POTWs with at
least secondary treatment of wastewater.
4-10
-------
TABLE 4-5
POLLUTANTS REGULATED UNDER PART 503
FOR SEWAGE SLUDGE FIRED IN A SEWAGE SLUDGE INCINERATOR
• Arsenic • Lead
• Beryllium* • Mercury*
• Cadmium • Nickel
• Chromium • Total Hydrocarbons
'Controlled through the existing National Emission Standards for Hazardous Air
Pollutants (40 CFR Part 61).
4-11
-------
SECTION FIVE
DEVELOPMENT OF LIMITS FOR INORGANIC POLLUTANTS
Through Subpart E of Part 503, EPA regulates eight pollutants in sewage sludge fired in
a sewage sludge incinerator or in the exit gas from the stack. The seven inorganic pollutants
regulated, all of which are metals, are arsenic, beryllium, cadmium, chromium, lead, mercury, and
nickel, while the organics are represented and regulated through total hydrocarbons (THC).
EPA regulates five of the metals—arsenic, cadmium, chromium, lead, and nickel—by
limiting the concentration of these pollutants in sewage sludge fed to a sewage sludge incinerator
on a site-specific basis. For beryllium and mercury, however, limits are not site-specific but have
been incorporated into Subpart E by reference to the NESHAP for Beryllium in Subpart C of 40
CFR Part 61 and the NESHAP for Mercury in Subpart E of 40 CFR Part 61. The regulation
also requires that THC be monitored in the stack gas and that THC emissions not exceed a
prescribed operational standard. The next section provides an overview of the Subpart E
pollutant limits and operational standard for sewage sludge fired in a sewage sludge incinerator.
5.1 OVERVIEW OF SUBPART E POLLUTANT LIMITS AND OPERATIONAL STANDARD
The Subpart E pollutant limits and operational standard are based on the following:
• Risk-specific Concentrations (arsenic, cadmium, chromium, nickel)
• National Ambient Air Quality Standard (lead)
• Technology-based Operational Standard (total hydrocarbons)
• National Emission Standards for Hazardous Air Pollutants (beryllium and
mercury)
Of the pollutants listed above, the limits for only four of them are derived through a risk-
based equation developed specifically for the Part 503 standard. This equation is used to
calculate a "risk-specific concentration" (RSC) for arsenic, cadmium, chromium, and nickel. An
5-1
-------
RSC is the allowable increase in the average daily ground-level ambient air concentration for a
pollutant above background levels that results from the firing of sewage sludge in a sewage
sludge incinerator.
The RSC is equivalent to the amount of pollutant that a person living near the sewage
sludge incinerator site can inhale daily with a probability of 1 in 10,000 (10"*) that the person will
contract cancer as a result of inhaling the pollutant. The probability of contracting cancer is a
theoretical upper bound estimate, and the probability can be as low as zero. RSC values are
calculated independently from background levels and pertain only to the concentration of the
pollutant emitted from the sewage sludge incinerator. RSCs for arsenic, cadmium, chromium,
and nickel are factored into a second equation, along with site-specific characteristics of the
sewage sludge incinerator, to develop limits on the concentration of these four pollutants in
sewage sludge.
The pollutant limit for lead is based on a percentage of the National Ambient Air Quality
Standard (NAAQS) for lead, not on a calculated RSC value. EPA allows sewage sludge
incinerators to increase the lead concentration in the ambient air around the incinerator site by
up to 10 percent of the NAAQS. This allowable ambient lead concentration substitutes for an
RSC value and is factored into an equation similar to that used for the four metals to calculate a
site-specific concentration limit for lead in sewage sludge.
In contrast to the pollutant limits based on RSCs or the NAAQS, the requirement for
THC is a technology-based operational standard, not a risk-based limit, because a methodology
for developing a site-specific risk-based approach for THC is not well established. This
operational standard is based on an approach that regulates all organic pollutants through one
THC emission value. The operational standard is based on the THC emission levels achievable
by multiple-health furnaces and was determined by an analysis of data on operations and THC
emissions from several sewage sludge incinerators. EPA used risk assessment methodology to
evaluate whether the THC operational standard protects public health from the reasonably
anticipated adverse effects of organic pollutants in the exit gas from a sewage sludge incinerator
stack. In the judgment of EPA, the THC operational standard is protective of public health.
5-2
-------
(See Section 6.6 for a further discussion of how risk assessment was used to judge that the THC
operational standard is protective of human health.)
According to the NESHAPs, beryllium and mercury are regulated as limits to air
emissions either by monitoring the exit gas from the sewage sludge incinerator stack or the
ambient air around the incinerator, or by monitoring the sewage sludge. Depending on the
pollutant, the monitoring methods are either listed in NESHAPs or are set by the permitting
authority. Although the proposed Part 503 rule, published February 6,1989, recommended that
the NESHAPs values for beryllium and mercury be used in equations to calculate allowable
concentrations of beryllium and mercury in sewage sludge, the final Part 503 rule uses the
NESHAPs values as the pollutant limits. The frequency of monitoring requirement for both
pollutants is specified by the permitting authority.
The remainder of Section Five explains the development of the inorganic pollutant limits.
Section 5.2 presents the equation EPA developed through risk assessment methodology that is
used to derive the RSCs for arsenic, cadmium, chromium, and nickel. This section also describes
the two other equations into which either an RSC or a percentage of the NAAQS for lead is
factored to calculate pollutant limits for the five metals. Section 5.3 discusses the factors EPA
used to develop the risk assessment methodology. Section 5.4 provides an explanation as to how
RSC values were calculated, while Section 5.5 explains the use of a percentage of the NAAQS
for lead to calculate the allowable limit on the concentration of lead in sewage sludge.
In Section 5.6, detailed explanations are given for the site-specific characteristics of a
sewage sludge incinerator unit that are used to calculate limits on the concentration of arsenic,
cadmium, chromium, lead, and nickel. Sample calculations derive limits for arsenic and lead at a
hypothetical POTW. The final section, Section 5.7, discusses EPA's policy decision to use the
NESHAPs for beryllium and mercury as the pollutant requirements of Subpart E.
5-3
-------
5.2 RISK-SPECIFIC CONCENTRATIONS AND THE EQUATIONS FOR DERIVING
LIMITS FOR INORGANIC POLLUTANTS IN SEWAGE SLUDGE
As mentioned in Section 5.1, EPA used risk assessment methodology to develop risk-
specific concentrations (RSCs), which are then used to calculate limits on the concentration of
arsenic, cadmium, chromium, and nickel in the sewage sludge. In Subpart E, RSCs are provided
for these four metals, all of which are carcinogens. These RSCs were calculated using Equation
1 below, which contains four risk-related factors—risk level (RL), body weight (BW), cancer
potency (q,*), and inhalation rate (I,). The only factor in this equation that is different for each
pollutant is the cancer potency value (qj"), which EPA previously has calculated for three of the
four metals (U.S. EPA, 1992a). The RSC is determined by the following equation:
RSC = RLxBW x 103 (1)
q/ »i.
where:
RSC = risk-specific concentration (jig/m3) for arsenic, cadmium, chromium, and
nickel
RL = risk level, or the probability of developing cancer, unitless
BW = body weight, in kilograms (kg)
qt* = cancer potency value for each carcinogenic metal, in milligrams per
kilogram-day (mg/kg-day)"1
I. = inhalation rate, in cubic meters per day (m3/day)
103 = conversion factor from milligrams to micrograras (1000 fig/rag)
The RSC for arsenic, cadmium, chromium, or nickel is input into a second equation that
includes three other variables, each of which relate to site-specific characteristics of the sewage
sludge incinerator unit. Equation 2 below presents the relationship among the four factors used
to calculate limits on the average daily concentrations (C) of the four metals in sewage sludge:
C = (RSC x 86,400)/(DF x [1-CE] x SF) (2)
5-4
-------
where:
C = the allowable average daily concentration of arsenic, cadmium, chromium,
or nickel in the sewage sludge, in milligrams per kilogram of total solids,
dry weight basis (mg/kg)
RSC = the risk-specific concentration, in micrograms per cubic meter (jig/m3)
DF = dispersion factor (the ratio of the increase in ground-level air
concentration at or beyond the property line to the mass emission rate for
the pollutant from the stack), in micrograms per cubic meter, per gram,
per second (/xg/mVg/sec)
CE = the sewage sludge incinerator control efficiency for arsenic, cadmium,
chromium, or nickel, in hundredths
SF = the sewage sludge feed rate, in metric tons per day, dry weight basis
(dmt/day)
86,400 = a conversion factor from seconds to days (86,400 sec/day)
The dispersion factor is calculated using an EPA-approved air dispersion model (U.S.
EPA, 1990b; 1986d), which accounts for such factors as stack height, stack diameter, stack gas
temperature, exit velocity, and surrounding terrain. In most cases, the actual stack height of the
sewage sludge incinerator is used in the model. If the stack height exceeds 65 meters, however, a
"creditable" stack height is used in the model based on "good engineering practice" (GEP) (see
Section 5.6.1.3).
The control efficiency regarding the percent removal of each metal pollutant is
determined by undertaking a performance test of the sewage sludge incinerator (see Section
5.6.2). During the performance test, the sewage sludge feed rate is either the average daily
amount of sewage sludge incinerated in all sewage sludge incinerators within the property line of
the site for the number of days the incinerators operate during the year or the average daily
design capacity for all sewage sludge incinerators within the site. For sites with more than one
sewage sludge incinerator, the feed rate is the average daily amount of sewage sludge for all
incinerators at the site. This rate is determined by dividing the sura of the amounts of sewage
sludge fed into each incinerator at the site during the calendar month by the total number of
days that all incinerators operated during that month.
5-5
-------
For lead, EPA did not develop an RSC value. Instead, the Agency chose an allowable
increase in the ambient air concentration for lead resulting from sewage sludge incineration and
expressed it in terras of a percentage of the NAAQS for lead. EPA concluded that a sewage
sludge incinerator can increase the lead concentration in the ambient air surrounding the
incinerator site by up to 10 percent of the NAAQS. Equation 3 shows how 10 percent of the
NAAQS for lead is used in place of an RSC to calculate the sewage sludge limit for lead:
C = (.10) (NAAQS) x 86,400/(DF x [1-CE] x SF)
(3)
where:
.10
NAAQS =
DF
CE
SF
86,400
the allowable average daily concentration of lead in the sewage sludge, in
milligrams per kilogram of total solids, dry weight basis (rag/kg)
the percentage of the NAAQS for lead that sewage sludge incinerators are
allowed to add to the lead concentration in the ambient air around the
incinerator site.
National Ambient Air Quality Standard for lead, in micrograms per cubic
meter (/ig/m3)
dispersion factor (the ratio of the increase in ground-level air
concentration of the pollutant at or beyond the property line to the mass
emission rate for the pollutant from the stack), in rnicrograms per cubic
meter, per gram, per second (/tg/raVg/sec)
the sewage sludge incinerator control efficiency for lead, in hundredths
the sewage sludge feed rate, in metric tons per day, dry weight basis
(dmt/day)
a conversion factor from seconds to days (86,400 sec/day)
5J EPA PART 503 RISK ASSESSMENT FOR INCINERATION
This section discusses the human exposure pathway assessed for sewage sludge
incineration and the factors EPA used to calculate RSCs. It also describes the concept of the
highly exposed individual that EPA used to ensure public health protection. In addition, this
5-6
-------
section explains the way in which EPA applied its risk assessment methodology to the
development of pollutant limits for Subpart E of the sewage sludge regulation.
5.3.1 Inhalation Pathway
To develop the Part 503 rule for sewage sludge fired in a sewage sludge incinerator, EPA
evaluated exposure only through direct inhalation of air emissions (U.S. EPA, 1988b).
5J.2 The Highly Exposed Individual
The risk-based equations developed for the Part 503 regulation were designed to limit
potential exposure of a highly exposed individual (HEI) to the pollutants of concern. The HEI is
an individual who remains for an extended period of time at the point of maximum ambient
ground-level pollutant concentration. For sewage sludge fired in a sewage sludge incinerator,
total concentration is limited so that the increased risk attributable to each carcinogenic pollutant
being emitted does not exceed an additional lifetime risk (70 years) of 1 x 10"* (1 in 10,000) to
the HEI.
The 1989 proposed Part 503 rule considered the exposed individual to be a "most exposed
individual" (MEI). EPA changed the terminology for the final rule based on a revised exposure
assessment analysis. The assessment for the final Part 503 regulation incorporates assumptions
that the Agency has concluded present a more realistic characterization of the potential for
reasonably anticipated adverse effects on public health. These assumptions are designed to limit
the potential exposure to a highly exposed individual (HEI) rather than to an MEI.
EPA's HEI exposure assessment analysis and the numerical pollutant limits developed
from that analysis are designed to address the risk to individuals and populations that may face a
greater risk than the general population from exposure to pollutants in sewage sludge. The
analysis attempts to evaluate realistic risk by using variables that are reflective of likely
experience. This approach does not evaluate the risk associated with a combination of unlikely
5-7
-------
occurrences, as did the MEI approach. EPA concluded that the HEI approach is consistent with
its statutory duty to develop regulations that are "adequate to protect public health and the
environment from any reasonably anticipated adverse effects." In the case of sewage sludge fired
in a sewage sludge incinerator, the assumptions used in the risk assessment methodology did not
change as a result of the change in terminology from the MEI to the HEI.
In developing Subpart E of the rule, EPA used the HEI to estimate the potential cancer
risk from direct inhalation of carcinogenic pollutants emitted from a sewage sludge incinerator.
The HEI is the person assumed to reside at the point of maximum, off-site, ground-level
concentration, with the point of maximum concentration being determined by air dispersion
modeling. EPA assumes that people do not routinely reside inside the facility boundary. For a
person firing sewage sludge from more than one sewage sludge incinerator unit, the point of
maximum exposure, and thus the location of the HEI, is determined by taking the sum of the
actual or projected emissions from the individual units at each receptor location.
5.3.3 Factors Used to Calculate Risk-Specific Concentrations
This section discusses the values chosen for the risk-based equation (Equation 1 from
Section 5.2) used to calculate RSCs.
RSC = RLxBW x 103
where:
RSC = risk-specific concentration (/tg/m3) for arsenic, cadmium, chromium, and
nickel
RL = risk level: 1 x 10"*, or 1 chance in 10,000 of developing cancer
BW = body weight: 70kg
q,* = cancer potency value for each carcinogenic metal, measured in (rag/kg-
day)'1
5-8
-------
I, = inhalation rate: 20 m3/day
103 = conversion factor
5.3.3.1 Risk Level
EPA's regulations are designed to achieve risk levels of between 1x10"* and MO'7 in a
number of regulatory applications, depending on the statute, surrounding issues, uncertainties,
and available data bases. For the Part 503 proposal, EPA chose the IxlO'5 risk level, or the
probability of 1 cancer case in 100,000 individuals, for sewage sludge fired in a sewage sludge
incinerator. Additional data provided by the NSSS, the scientific peer review committees, and
the public were incorporated into an aggregate effects assessment for the final rule, which
considers the health effects on the HEI and the population as a whole. This assessment showed
minimal risk from current sewage sludge use or disposal practices. Because sewage sludge
incinerators exhibited low baseline risk, the Agency chose to regulate sewage sludge incinerator
units such that each carcinogen in the emissions does not exceed an incremental unit risk of 1 x
10"4 to the HEI. The incremental risk is considered as that which is caused only by emissions
from a sewage sludge incinerator unit and not from other sources, natural or manmade.
5.3J.2 Body Weight
As defined by EPA, lifetime inhalation exposures are estimated for a 70 kg man (154
pounds), which is considered the standard body weight of an adult male (U.S. EPA, 1990a).
5.3 JJ Cancer Potency
The cancer potency value (q,*) represents the relationship between a specified
carcinogenic dose and its associated degree of risk. The qt* is based on continual exposure of an
individual to a specified concentration over a period of 70 years. Established EPA methodology
for determining cancer potency values assumes that any degree of exposure to a carcinogen
5-9
-------
produces a measurable risk. The q,' value is expressed in terms of risk per dose and is measured
in reciprocal units of milligrams of pollutant per kilogram of body weight and per day of
exposure (mg/kg-day)'1. For example, the qt' value for arsenic is 15 (mg/kg-day)'1. The arsenic
q,' of 15 (mg/kg-day)'1 is then factored into the RSC equation to obtain an allowable increase in
the ambient air concentration of arsenic resulting from sewage sludge incineration.
EPA previously has calculated cancer potency estimates for arsenic, cadmium, and
chromium, which appear in the Agency's Integrated Risk Information System (IRIS) database
(U.S. EPA, 1992a), and are shown in Table 5-1. The cancer potency for chromium is shown for
its carcinogenic form, hexavalent chromium. RSCs for arsenic, cadmium, and chromium are
based in part on their cancer potency values. The RSC for nickel subsulfide (the carcinogenic
form of nickel) was taken directly from the IRIS database. EPA also compiles scientific data on
the observed health effects from exposure to a large number of pollutants in its IRIS database.
The "most sensitive endpoint" for humans exposed to the four carcinogens regulated in Subpart
E are listed in IRIS as follows: arsenic (lung, skin, and gastrointestinal cancers); cadmium (lung,
tracheal, and bronchial cancer); hexavalent chromium (lung cancer and cancers in other organs);
and nickel subsulfide (lung and nasal cancer) (U.S. EPA, 1992a).
5.33.4 Inhalation Rate
EPA uses 20 m3/day as the amount of air inhaled long-term by the HEI. The Agency
regards this value as the standard inhalation rate of an adult male during a normal day (U.S.
EPA, 1990a).
TABLE 5-1
CANCER POTENCY VALUES (q,*) FOR METALS
METALS
Arsenic
Cadmium
Hexavalent Chromium
q,' (mg/kg-day)'1
15.0
6.1
41.0
Source: U.S. EPA Integrated Risk Information
System, 1992a.
5-10
-------
5.4 DERIVATION OF RISK-SPECIFIC CONCENTRATIONS FOR THE CARCINOGENIC
METALS
Subpart E of the Part 503 rule provides RSC values for arsenic, cadmium, chromium, and
nickel that can be used to calculate allowable pollutant concentrations in sewage sludge given the
site-specific variables associated with each sewage sludge incinerator. These RSCs are shown in
Table 5-2. The RSC for chromium depends on the type of sewage sludge incinerator unit and
air pollution control equipment used. Optionally, treatment works staff can calculate a site-
specific RSC value for chromium based on the percentage of hexavalent chromium to total
chromium in the emissions from the sewage sludge incinerator. The RSC for nickel was based
on the detection limit for the percentage of nickel subsulfide to total nickel analyzed in the stack
gas from several sewage sludge incinerators.
TABLE 5-2
RISK-SPECIFIC CONCENTRATIONS FOR METALS
METAL
Arsenic
Cadmium
Chromium
Fluidized-bed with scrubber
Fluidized-bed with wet scrubber
and wet electrostatic precipitator
Other types with wet scrubber
Other types with wet scrubber and
wet electrostatic precipitator
Nickel
RISK-SPECIFIC
CONCENTRATION
Gtg/m3)
0.023
0.057
0.65
0.23
0.064
0.016
2.0
Source: 40 CFR Part 503, Subpart E.
5-11
-------
5.4.1 RSC Calculations for Arsenic and Cadmium
The RSCs for arsenic and cadmium are calculated below, using Equation 1 from Section
5.2 and the standard values for risk level, body weight, and inhalation rate, and the cancer
potency value for each metal from Table 5-1. Following these RSC calculations are discussions
of the standard and site-specific RSGs for chromium, including calculations for each of the four
standard chromium RSCs, and of the RSC for nickel, including the calculation for the nickel
RSC.
RSC =RL x BW x 103
q,**i.
where:
RSC = risk-specific concentration (/ig/ni3) for arsenic, cadmium, or chromium
RL = risk level: 1 x lO"4
BW = body weight: 70 kg
qt* = cancer potency value for each carcinogenic metal (listed in Table 5-1), in
(mg/kg-day)-1
I, = inhalation rate: 20 m3/day
103 = conversion factor: 1000 j*g/rag
RSC (arsenic) = 0.0001 x 70 kg x 1,000 jig/mg
15.0 (mg/kg-day)'1 x 20 mj/day
0.023 Mg/m3
RSC (cadmium) = 0.0001 x 70 kg x 1,000 jig/mg
6.1 (rng/kg-day)'1 x 20 mj/day
0.057 Mg/m3
5-12
-------
5.4.2 RSC Calculation for Chromium
Chromium is emitted from sewage sludge incinerators either in the noncarcinogenic
trivalent state (Cr*3), or in the highly carcinogenic, hexavalent state (Cr*6). Trivalent chromium
is toxic only at levels higher than those normally found in sewage sludge or emitted from sewage
sludge incinerators. For the Part 503 proposal, EPA estimated that one percent of the
chromium emitted from a sewage sludge incinerator was in its most toxic form, hexavalent
chromium. This estimate was based on limited EPA chromium emission data.
After the Part 503 proposal was published, EPA conducted a series of tests at three
sewage sludge incinerators to determine more accurately the percentage of chromium converted
during combustion to the hexavalent state (U.S. EPA, 1991a; 1991b; 1991c). The three sewage
sludge incinerator units were equipped with the following incinerator and APCDs: (1) a
multiple-hearth furnace with a venturi scrubber system; (2) a fluidized-bed furnace with a venturi
scrubber and a pilot-scale wet electrostatic precipitator (WESP); and (3) a multiple-hearth
furnace with a venturi scrubber and a WESP.
These tests for chromium conversion were made possible because of the recent
development of a sophisticated stack sampling method (U.S. EPA, 1992b) that minimizes the
conversion of hexavalent chromium back to the trivalent state in the sampling and analysis
process (Steinsberger et al., 1992). Overall, the EPA tests determined that most of the
chromium is emitted in the trivalent state because hexavalent chromium is more highly reactive,
and thus reacts with reducing agents to form the more stable and less toxic trivalent chromium.
Based on the EPA tests of the three sewage sludge incinerators, the Agency also
concluded that the conversion to hexavalent chromium varies with the type of sewage sludge
incinerator and air pollution controls. First, the fluidized-bed furnace produced a lower degree
of conversion of chromium to hexavalent chromium than the multiple-hearth furnaces. Second,
the use of a WESP tends to increase the percentage of hexavalent chromium measured at the
outlet of the WESP as a result of a higher collection efficiency of trivalent chromium by the
WESP (U.S. EPA, 1991d; U.S. EPA, 1992c; Steinsberger et al., 1992).
5-13
-------
Based on the results of the above tests, EPA derived different RSC values for four
combinations of sewage sludge incinerator and APCD technologies. To develop chromium
concentration limits in the sewage sludge, the RSC value for the appropriate technologies at the
incinerator should be used. The four RSCs for chromium for the various technologies are listed
in Table 5-2. Chromium RSCs are highest for fluidized-bed furnaces with a wet scrubber and no
WESP and lowest for other furnace types with a wet scrubber and a WESP. The lower the RSC
value, the lower will be the calculated chromium concentration limit.
EPA used Equation 4 below to calculate the standard chromium RSCs based on the
percentage of hexavalent chromium in the total chromium concentration emitted during the
emission tests at the three sewage sludge incinerators. The 0.0085 value in Equation 4 is the
RSC for 100 percent hexavalent chromium. Shown below are Equation 4 and the calculation for
the 0.0085 value, which is based on the q,* for hexavalent chromium.
RSC = 0.0085/r
where:
RSC =
(4)
RSC for chromium, in micrograms per cubic meter (/ig/m3)
decimal fraction of hexavalent chromium in the total chromium
concentration, in hundredths
RSC (100% bexavalent chromium) =
0.0001 x 70 kg x 1,000/ig/rng
41.0 (mg/kg-dayyl x 20 mVday
0.0085 pg/m3
Table 5-3 shows the percentage of hexavalent chromium to total chromium by furnace
type and APCD. The percentages are based on the 95th percentile values derived from the
5-14
-------
TABLE 5-3
PERCENTAGE OF HEXAVALENT CHROMIUM TO TOTAL CHROMIUM
BY FURNACE TYPE AND AIR POLLUTION CONTROL DEVICE
FURNACE TYPE
Fluidized Bed
Multiple Hearth
POLLUTION CONTROL DEVICE
Scrubber
1.3%
13.2%
Scrubber Plus WESP
3.7 %
50.9 %
Source: U.S. EPA, 1991d.
EPA tests on the three sewage sludge incinerators (U.S. EPA, 1991d). Data from the EPA tests
on which the chromium RSCs in Table 5-2 are based are presented in Appendix C, along with a
discussion of the test results. Presented below are the calculations for the four RSCs for
chromium using Equation 4 and the percentages of hexavalent chromium from Table 5-3,
expressed in hundredths.
RSC = 0.0085/r
(a) RSC = 0.0085/.013 (c) RSC = 0.0085/.132
0.65 = 0.064
(b) RSC = 0.0085/.037 (d) RSC = 0.0085/.509
0.23 = 0.016
Since the RSC values for chromium developed by the Agency are estimates based on the
95th percentile values for the percentage of hexavalent chromium in sewage sludge incinerator
emissions, treatment works staff also can decide to calculate a site-specific RSC based on the
percentage of hexavalent chromium to total chromium in the stack emissions (see EPA-approved
test methodology (U.S. EPA, 1992b)). This calculation, shown below, uses the same equation as
that used to calculate the four standard chromium RSCs.
5-15
-------
RSCsp = 0.0085/r (5)
where:
RSCsp = site-specific RSC for chromium, in micrograms per cubic
meter (/tg/mj)
r . = decimal fraction of hexavalent chromium in the total
chromium concentration, in hundredths
5.4J RSC Calculation for Nickel
In the proposed Part 503 regulation, EPA assumed that 100 percent of the nickel emitted
from a sewage sludge incinerator unit was in the carcinogenic form, nickel subsulfide. To obtain
more accurate data on nickel emissions for the final regulation, EPA conducted nickel speciation
tests at the same two multiple-hearth furnaces and one fluidized-bed furnace at which chromium
tests were conducted (U.S. EPA, 1991a; 1991b; 1991c). These tests were based on both new and
established testing and sampling techniques. EPA contractors used two analytical methods: a wet
chemical speciation technique to measure the nickel species and two instrumental techniques
using atomic absorption spectroscopy to confirm the presence or absence of the different nickel
species (Steinsberger et al., 1992).
The nickel speciation samples were taken at three locations within the sewage sludge
incinerator: at the inlet to the air pollution control device from the furnace; at the outlet from
the air pollution control device; and at the midpoint between the scrubber and wet electrostatic
precipitator, when both of these air pollution control devices were present. The results of the
nickel speciation analysis (see Appendix D) revealed that nickel subsulfide is not emitted from
sewage sludge incinerators above the level of detection for both analytical techniques. For
multiple-hearth furnaces, the detection limit is 12 percent for the inlet emissions and 10 percent
for the outlet emissions, and for the fluidized-bed furnace, the detection limit is 2 percent in the
inlet emissions and 1 percent in the midpoint emissions. To be conservative,-EPA based the
standard RSC value for nickel on the higher of the two detection limits for nickel subsulfide (10
5-16
-------
percent) measured at the outlet from the APCD. The RSC derivation below uses the RSC for
nickel subsulfide obtained from IRIS and revises the RSC for 10 percent nickel subsulfide.
RSC nickel = 0.20 gg/m3 (100 percent nickel subsulfide)
0.10
= 2.0 jig/m3 (10 percent nickel subsulfide)
5.5 USE OF A PERCENTAGE OF THE NATIONAL AMBIENT AIR QUALITY STANDARD
FOR LEAD
While pollutant limits for the carcinogenic metals are calculated using RSC values, the
lead limit is calculated using a percentage of the existing National Ambient Air Quality Standard
(NAAQS) for lead, which currently is 1.5 /tg/raj (40 CFR Part 50.12). While lead is now
classified as a "probable" human carcinogen, the Clean Air Scientific Advisory Committee of the
Science Advisory Board recommended that the NAAQS for lead be based on noncarcinogenic
health effects. EPA considers developmental neurotoxity to be the most sensitive endpoint for
lead exposure (U.S. EPA, 1986c).
For the Part 503 proposal, EPA considered two alternatives for the percentage of the
NAAQS to use to represent the allowable increase in ambient air concentration for lead: 10
percent and 25 percent. The final rule allows a sewage sludge incinerator to increase the lead
concentration in the ambient air around the incinerator site by up to 10 percent of the NAAQS.
EPA concluded that this lower fraction is warranted due to concern about overexposure of the
public to lead. It also appears that almost every sewage sludge incinerator currently can restrict
lead emissions so that the resulting increase in the ground-level ambient air concentration of lead
is no greater than 10 percent of the NAAQS.
5-17
-------
5.6 DERIVATION OF THE LIMITS ON THE CONCENTRATION OF ARSENIC,
CADMIUM, CHROMIUM, LEAD, AND NICKEL IN SEWAGE SLUDGE
Subpart E requires that limits be calculated for the five metals using either Equation 2 or
Equation 3, from Section 5.2. These equations factor in values for the dispersion factor (DF),
control efficiency (CE), and sewage sludge feed rate (SF) that are specific to each sewage sludge
incinerator, along with an RSC for arsenic, cadmium, chromium, or nickel, or a percentage of
the NAAQS for lead.
In the Part 503 proposal, pollutant limits for the incineration of sewage sludge were to be
determined in one of three ways. At the first and simplest level, the dispersion factors and
control efficiencies provided in the proposed regulation, which are based on a simplified air
dispersion analysis technique, could be used to calculate the limits. If the allowable sewage
sludge concentrations could not be met, a site-specific value for the dispersion factor and a
control efficiency value provided in the regulation could be used to calculate the limits. If
compliance still could not be demonstrated at this second level, site-specific tests for dispersion
factors and control efficiencies could both be used. This third level required performance tests
and stack sampling of emissions to compute control efficiencies.
The final rule requires that the metals limits be based on site-specific conditions.
Dispersion factors and control efficiencies are not provided in the regulation.
The dispersion factor, control efficiency, and sewage sludge feed rate have be derived
independently and site-specifically. These factors, however, are also interdependent. For
example, in deriving the metals limits, either the average daily design capacity of the sewage
sludge incinerator or the average daily amount of sewage sludge fed to the incinerator could be
used. Choosing the capacity feed rate results in a lower allowable metal concentration in the
sewage sludge. On the other hand, using the average daily amount, which is often a lower feed
rate, will increase the allowable metal concentration. Another factor that effects the calculated
metal concentration limit is the control efficiency of the APCD(s). Installation of an additional
APCD may tend to increase the allowable metal concentration limit in the sewage sludge. The
5-18
-------
three site-specific factors that are used to determine the metals concentration limits in the
sewage sludge are described below.
5.6.1 Dispersion Factor
The dispersion factor correlates the emission rate for a pollutant with the resulting
increase in the ambient ground-level pollutant concentration in the air around the sewage sludge
incinerator and is expressed in the following manner:
Dispersion Factor = increase in ambient ground-level pollutant concentration (ug/m3)
emission rate (g/sec)
The dispersion factor is determined through the use of air dispersion models. Site-
specific air dispersion modeling conducted for the purpose of establishing pollutant limits under
Part 503 can be based on procedures in the Guidelines on Air Quality Models (GAQM) (Revised)
(U.S. EPA, 1990b; 1986d) if approved by the permitting authority. The GAQM is the principal
source of information on the proper selection and regulatory application of air dispersion
models. It also provides recommendations on the relevant databases and requirements for
modeling ambient air concentrations.
This section summarizes procedures contained in the GAQM. Successful performance of
a detailed air dispersion modeling analysis requires a knowledgeable air quality modeler,
adequate computer resources, and the ability to assemble the meteorological and source
parameter data required for model input.
5.6.1.1 Mod* Selection
The model selected for deriving the dispersion factor should be the one that most
accurately represents atmospheric transport and dispersion in the area around the sewage sludge
incinerator. Atmospheric dispersion models have been developed for both simple and complex
5-19
-------
terrain and for rural and urban applications. The topography and land use in the area
surrounding the incinerator must be.evaluated to determine the type of model that applies to the
:pecific situation.
Terrain Typ«. One of the initial determinations to make in model selection regards the
type of terrain surrounding the incinerator. If all the terrain in the surrounding area is below the
incinerator's lowest stack elevation, incinerator impacts can be adequately addressed with a
simple terrain model. If terrain elevations above the lowest stack elevation are identified, use of
a complex terrain model is required. Receptors with terrain elevations between the stack height
and the plume height (intermediate terrain receptors) must be modeled with both a simple and a
complex terrain model.
Urban/Rural Classification. Aside from terrain type, the second major determination to
make in model selection regards the urban/rural classification for the area. This determination is
typically based on the land use in the area surrounding the emission source. The GAQM
provides guidance on acceptable land use classification procedures. Sources located in an urban
area should be modeled using urban plume dispersion coefficients, while sources located in a
rural area should be modeled using rural plume coefficients. Some models incorporate both
urban and rural dispersion coefficients. Other models, particularly those addressing complex
terrain, generally accommodate one land use classification or the other.
Simple Terrain. The GAQM identifies both simple and complex terrain models. Simple
terrain is defined as terrain elevation below the incinerator's stack elevation. The simple or
"noncoraplex" terrain model recommended for this situation is the Industrial Source Complex
Long-Term model (ISCLT2). The ISCLT2 model is intended for rural or urban areas where
terrain elevations do not exceed the stack height. For details on the ISCLT2 model execution
and input requirements, consult the User's Guide for the Industrial Source Complex (ISC2)
Dispersion Models - Volumes I, II, III (U.S. EPA, 1992d) and the Sludge Incineration Modeling
(SIM) System User's Guide (U.S. EPA, I990c).
Complex Terrain. The air dispersion models most often recommended for use in
complex terrain, where terrain elevations exceed the sewage sludge incinerator stack height, are
5-20
-------
the LONGZ and COMPLEX I models. LONGZ is intended for complex urban terrain, wh.
COMPLEX I is intended for complex rural terrain.
5.6.1.2 Source Parameters
Certain source parameters are required for input to air dispersion models. The stack gc
flow rate and the gas exit velocity used as inputs to these models must be confirmed in the field.
The input variables typical for sewage sludge incinerator stacks include:
Stack height above ground level
Inside stack diameter
Gas velocity at stack exit"
Gas flow rate*
Gas temperature at stack exit*
Stack-base elevation
Dimensions of nearby buildings
Stack coordinates (based on distance from grid origin)
Emission rate of pollutant*
Fenceline coordinates (based on distance from grid origin to points along the
fenceline)
'these variables are determined from or during a performance test
5.6.1.3 Good Engineering Practice Stack Height
Good Engineering Practice (GEP) stack height standards were developed by the Agency
to avoid the construction of tall stacks built for the sole purpose of reducing excessive ground-
level ambient air concentrations by dilution. Such a practice may not reduce, and may even
increase, the cancer potential to the aggregate population. The GEP stack height plays an
integral role in determining the impact that sewage sludge incinerator emissions have on ambient
air quality. The physical stack height input for modeling cannot be greater than the GEP stack
height. If the physical stack height is found to exceed the GEP stack height, the GEP value must
be used.
5-21
-------
For incinerators with stacks shorter than 65 meters, the actual stack height should be
used in the air dispersion model. Most sewage sludge incinerators that are currently operating
have stacks shorter than 65 meters. For sewage sludge incinerators with stack heights in excess
of 65 meters, Equation 6 presented below must be used to determine the GEP stack height for
modeling purposes, as cited in 40 CFR 51.100(ii).
H, = H + 1.5L (6)
where:
Hg = good engineering practice stack height, measured from the ground-level
elevation at the base of the stack
H = height of nearby structure(s) measured from the ground-level elevation at
the base of the stack
7
L = lesser dimension, height or projected width, of nearby structure(s)
The requirement to meet the equation above applies to all sewage sludge incinerators
with a stack height in excess of 65 meters built after January 12,1979:
"...provided that the EPA, State or local control agency may
require the use of a field study or fluid model to verify GEP stack
height for the source; or the height demonstrated by a fluid model
or a field study approved by the EPA, State or local control
agency, which ensures that the emissions from a stack do not result
in excessive concentrations of any air pollutant as a result of
atmospheric downwash, wakes, or eddy effects created by the
source itself, nearby structures or nearby terrain features"
[40 CFR 51.1(ii)J.
Sewage sludge incinerators with stack heights in excess of 65 meters and which were in
existence on January 12,1979, were required to use a second formula to determine the effective
stack height. However, because no sewage sludge incinerators in the United States had stack
heights in excess of 65 meters prior to January 12,1979, this other formula does not apply.
Sewage sludge incinerator units in existence on December 31,1970, are not subject to this
5-22
-------
regulation. The actual stack height at these facilities is considered to be the GEP height in the
modeling calculations.
5.6.1.4 Building Downwash Factor
Most sewage sludge incinerators have short stacks that are not much higher than the
buildings on which they are located. As a result, the incinerator plumes are impacted by the
wake effect created by the buildings and are deflected onto the ground in the area surrounding
the building. Because of this aerodynamic building downwash effect, the highest ground-level
concentrations of pollutants usually are found close to the incinerator. According to the GAQM,
the ISCLT model is the only EPA-accepted model that considers the effect of building downwash
in computing ground-level air concentrations of pollutants that occur close to the incinerator.
Building downwash should be included in the modeling analysis for all stacks with heights
less than the GEP height. The ISCLT model contains algorithms for determining building
downwash. Methods and procedures for determining the appropriate inputs to account for
downwash are discussed in the user's guide for ISCLT and the Guideline for Determination of
Good Engineering Practice Stack Height (Technical Support Document for the Stack Height
Regulations - Revised) (U.S. EPA, 1985i).
5.6.13 Meteorological Data
Meteorological data used as input data to an air quality dispersion model should be
spatially and temporally representative of the area of interest. These data are typically collected
by the National Weather Service (NWS) or as part of an on-site measurement program. Other
sources of meteorological data may include local universities, the Federal Aviation
Administration (FAA), military stations, or pollution control agencies. The NWS and military
station data may be purchased from the National Climatic Data Center in Asheville, North
Carolina. NWS data are also available on the Support Center for Regulatory Air Model's
(SCRAM) Electronic Bulletin Board System (BBS), managed by EPA's Office of Air Quality
5-23
-------
Planning and Standards (OAQPS) Source Receptor Analysis Branch of the Technical Support
Division.
Guidance on determining representative meteorological data and recommendations for
the collection and use of on-site meteorological data are provided in the GAQM, On-Site
Meteorological Program Guidance for Regulatory Modeling Applications (U.S. EPA, 1987a), and
Ambient Monitoring Guidelines for Prevention of Significant Deterioration (PSD) (U.S. EPA,
1987b). Further information on meteorological data collection is provided in the Quality
Assurance Handbook for Air Pollution Measurement Systems: Volume IV, Meteorological
Measurements (U.S. EPA, 1983b). Determinations of the appropriate nature of meteorological
data is made on a case-by-case basis in consultation with the state or regional air quality
meteorologist.
In terms of meteorological data application, some models use hourly weather
observations and twice-daily mixing height data, which are preprocessed into a format suitable for
model execution. Models designed to predict long-term averages, such as ISCLT2, commonly
use Stability Array (STAR) summaries, which are joint frequency distributions of wind speed,
wind direction, and Pasquill-Gifford atmospheric stability class.
5.6.1.6 Model Availability
Source code or executable code for the dispersion models can be purchased from the
National Technical Information Service (NTIS) or obtained without charge from the SCRAM
BBS. Other sources of model code include private vendors. Private vendors frequently supply
interactive or menu-driven data entry programs that can considerably simplify the modeling
effort. Moddera should verify that they are using the most up-to-date version of the model,
particularly when purchasing models through NTIS or private vendors.
5-24
-------
5.62 Control Efficiency
The control efficiency parameter is determined by site-specific performance tests that
measure the degree to which the sewage sludge incinerator and associated APCDs remove a
given pollutant from the stack emissions. The control efficiency for a sewage sludge incinerator
directly relates the quantity of a pollutant in the sewage sludge that is fed into an incinerator to
the quantity of the pollutant emitted from the stack. Thus, for example, if a quantity of sewage
sludge being fed to the incinerator contains 100 grams of lead and only 1 gram of lead is emitted,
the incinerator has a 99-percent control efficiency for lead. Performance tests also are required
because they will generate data on which to base the operating ranges that will be used for an
incinerator's permit conditions.
EPA has prepared guidance on the performance test needed to develop the control
efficiency for a sewage sludge incinerator. This document is entitled, POTW Sludge Sampling and
Analysis Guidance Document (Volume II) (U.S. EPA, 1992e), which replaces the document
entitled, Guidance Document for Testing and Permitting Sewage Sludge Incinerators (MRI, 1990).
There are three major elements of a stack test conducted to derive the control efficiency
for a sewage sludge incinerator
• Sampling and analysis of the sewage sludge for five metals (arsenic, cadmium,
chromium, lead, and nickel)
• Sampling and analysis of stack emissions for the five metals
• Monitoring and documentation of operating conditions during the test (including
temperature(s), oxygen, and sewage sludge feed rate)
For a list of general guidelines appropriate for conducting a performance test, see Appendix E.
Specific EPA methods for sampling and analysis of metal emissions for the derivation of
control efficiency values for sewage sludge incinerators include Method 12 for lead (40 CFR Part
*
60, Appendix A) and Method 108 for arsenic (40 CFR Part 61, Appendix B). A new sampling
and analytical method for hexavalent chromium has recently been validated by EPA (U.S. EPA,
5-25
-------
1992b). These methods may be applicable to sewage sludge incinerators in cases where only one
metal is being investigated. However, a method has been finalized for the emissions sampling
and analysis for multiple metal analytes. It is entitled, "Methodology for the Determination of
Metals Emissions in Exhaust Gases From Hazardous Waste Incineration and Similar Combustion
Processes." The method can be applied to 16 analytes, making the Multiple Metals Method
highly appropriate for the sampling and analysis of the five metals as they are emitted in the exit
gas from a sewage sludge incinerator. The Multiple Metals Method, however, only measures
total chromium and does not distinguish between total chromium and hexavalent chromium. A
copy of this final method can be found in the Methods Manual for Compliance with the BIF
Regulation (U.S. EPA, 1991e) and in the POTW Sludge Sampling and Analysis Guidance
Document (Volume II) (U.S. EPA, 1992e). This latter document also recommends a quality
assurance/quality control (QA/QC) plan for sewage sludge sampling and analysis. A QA/QC
plan is recommended to ensure that the field sampling and laboratory analysis will provide data
of sufficient quality for regulatory compliance.
5.6.3 Sewage Sludge Feed Rate
During the performance test, a sewage sludge feed rate is selected that is either the
average daily amount of sewage sludge fired in all sewage sludge incinerators within the property
line of the site for the number of days in a 365 day period that each sewage sludge incinerator
operates or the average daily design capacity for all sewage sludge incinerators within the
property line of the site. The sewage sludge feed rate will be determined as part of a permit
strategy once the actual concentration of the pollutants of concern in the sewage sludge is known
and the control efficiency and dispersion factor are calculated. In general, the higher the feed
rate, the "cleaner" the sewage sludge quality must be to meet the pollutant concentration limit.
5.6.4 Example of Calculation for the Arsenk Limit
As required by Subpart E, site-specific limits are calculated for five metals in the sewage
sludge. These calculated limits become part of the treatment works permit requirements. This
section includes an example of a calculation for the limit on arsenic using values for the
5-26
-------
dispersion factor, control efficiency, and sewage sludge feed rate that are representative of a
typical sewage sludge incinerator.1 For the arsenic limit, the RSC for arsenic provided in
Subpart E is used. Equation 2 from Section 5.2 is used below to calculate the pollutant limit for
arsenic:
C = (RSC x 86,400)/(DF x [1-CE] x SF)
where:
C = the allowable average daily concentration of arsenic in the sewage sludge (mg/kg)
RSC = risk-specific concentration for arsenic: 0.023 jtg/m3
DF = dispersion factor: 3.4 (/tg/m3/g/sec)
CE = the sewage sludge incinerator control efficiency: 0.975
SF = the sewage sludge feed rate: 12.86 dmt/day
86,400 = conversion factor 86,400 sec/day
CraBic = (0.023 /ig/m3 x 86,400 sec/day)/(3. 40ig/m3/g/sec) x [1-0.975] x 12.86 drat/day)
= 1,818 mg/kg
5.6.5 Example of Calculation for the Lead Limit
The following calculations derive the limit on the concentration of lead using Equation 3
from Section 5.2:
C = (.10)(NAAQS) z 86,400/(DF x [1-CE] x SF)
'The values for the dispersion factor and the sewage sludge feed rate are from POTW 353 listed in the
National Sewage Sludge Survey. POTW 353 is a representative multiple-hearth furnace. The values for the
control efficiency for arsenic and lead emissions represent the median control efficiency observed at multiple-
hearth furnaces from the National Sewage Sludge Survey.
5-27
-------
where:
C = the allowable average daily concentration of lead in the sewage sludge, in
milligrams per kilogram of total solids, dry weight basis (mg/kg)
.10 = the percentage of the NAAQS for lead that sewage sludge incinerators are
allowed to add to the lead concentration in the ambient air around the incinerator
site.
NAAQS = National Ambient Air Quality Standard for lead: 1.5 /ig/m3
DF = dispersion factor 3.4 (/ig/m3/g/sec)
CE = sewage sludge incinerator control efficiency: 0.916
SF = sewage sludge feed rate: 12.86 drat/day
86,400 = conversion factor: 86,400 sec/day
C,^ =1-5 fig/m3 x 8,640/(3.4(/tg/m3/g/sec) x [1-0.916] x 12.86 dmt/day)
C,^ = 3,529 mg/kg
5.7 POLLUTANT LIMITS FOR BERYLLIUM AND MERCURY
Beryllium and mercury are regulated under the NESHAPs, 40 CFR Part 61, Subpart C and
Subpart E, respectively. Subpart E of Part 503 requires that the NESHAPs for these two metals,
which are health-based, not be violated. The beryllium NESHAP, however, only applies to a
person firing sewage sludge who receives beryllium-bearing waste at the treatment works.
Because only a few facilities fall into this category, beryllium is most often not required to be
monitored. For a treatment works that knows it receives beryllium-bearing waste, it must test for
beryllium as part of the performance test to determine permit conditions. From this test, the
permitting authority will determine whether beryllium monitoring limits will be required as a
permit condition. The beryllium NESHAPS requires that, during the performance test, beryllium
be analyzed in emissions and in the sewage sludge and that all operating conditions be
documented.
In the proposed Part 503 rule, beryllium and mercury were to be regulated in the sewage
sludge along with the other metals. The Part 503 proposal contained an equation for calculating
the beryllium and mercury limits in the sewage sludge that was developed specifically for these
5-28
-------
two metals. The final Part 503 rule uses the NESHAPs for each metal as the regulated limits.
The appropriate methods for analysis are listed in 40 CFR Part 61, Subpart C and E,
respectively. The POTW Sludge Sampling and Analysis Guidance Document (Volume II)
recommends a sewage sludge analysis method for beryllium, if necessary.
The NESHAPs for beryllium emissions from sewage sludge incinerators is stated either as a
limit on the rate of emissions from the stack (10 g/day) or as a limit on the ambient air
concentration of beryllium in the vicinity of the sewage sludge incinerator (0.01 jig/ra3, averaged
over a 30-day period). The beryllium NESHAPs also contains requirements for stack sampling
and air sampling, as well as a provision that the permitting authority may approve an alternative
method (40 CFR Part 61.13(h)(l)(ii)).
The NESHAPs for mercury emissions from sewage sludge incinerators is a limit on the rate
of emissions from the stack (3,200 g/day). However, a sewage sludge incinerator can show
compliance by either monitoring the air emissions or the sewage sludge for mercury. The
NESHAPs provides an equation that relates sewage sludge concentration to emissions and
factors in the sewage sludge feed rate and the weight fraction of solids in the sewage sludge. If
the mercury concentration in the sewage sludge is monitored, Method 105 in Appendix B of the
NESHAPs must be used. The mercury NESHAPs contains additional requirements for stack
sampling and sewage sludge sampling.
Although beryllium currently is considered a carcinogen, it was considered a noncarcinogen
at the time the NESHAP for beryllium was established in 1973. Therefore, the NESHAPS limit
was considered to protect against noncarcinogenic health effects from beryllium exposure. The
most sensitive endpoint for exposure to beryllium through the inhalation pathway is inflammation
and granulomatous lesion of the lung (Cullen, 1987) and that for mercury, also considered a
noncarcinogea at the time the NESHAP was established, is irreversible damage to the central
nervous system (U.S. EPA, 1984).
5-29
-------
SECTION SIX
DEVELOPMENT OF THE OPERATIONAL STANDARD FOR
TOTAL HYDROCARBONS
EPA regulates organic compounds emitted from sewage sludge incinerators by limiting
emissions of total hydrocarbons (THC). The THC standard of 100 ppm, measured by use of a
THC monitor with a "hot" sampling line and corrected to 7-percent oxygen and for zero-percent
moisture is measured at the stack. The THC operational standard is based on THC emissions
data from several sewage sludge incinerators and represents what is achievable with available
technology at a sewage sludge incinerator. To judge whether this THC operational standard is
also protective of public health to the 1 x 10^ risk level, EPA used risk assessment methodology
and based its calculations on data from the National Sewage Sludge Survey.
This section first explains EPA's decision to use THC as a surrogate for organic emissions
from sewage sludge incinerators. Section 6.2 discusses the statutory basis for regulating THC
through a technology-based operational standard instead of by setting a risk-based limit. Section
6.3 provides the basis for setting the operational standard at 100 ppm measured with the
previously mentioned monitoring device and corrected for oxygen and moisture content. Section
6.4 outlines the THC emission excursion policy, while Section 6.5 explains the correction factors
for oxygen and moisture content. In Section 6.6, the risk-based analysis of the THC operational
standard is provided. This section presents the equations used to determine the degree of risk
posed by the operational standard and discusses the factors used in these equations, such as the
dispersion factor, the gas flow rate, and the weighted qj*, to derive site-specific, risk-specific
concentrations (RSCs) and risk levels for THC.
6.1 THC AS A SURROGATE FOR ORGANIC EMISSIONS
EPA regulates the emission of organic pollutants from sewage sludge incinerators by
setting a limit on the concentration of total hydrocarbons (THC) measured in the stack gas.
6-1
-------
Organic pollutants are chemical compounds that contain one or more carbon atoms.
Hydrocarbons are the simplest organic compounds and contain only carbon and hydrogen atoms.
There are several difficulties in monitoring organic emissions. Most important is that
sampling and analysis techniques are not available to identify or quantify all potential organic
compounds emitted from sewage sludge incinerators, nor are toxicity data available for all
compounds. At present, only a few tests have been conducted to identify and quantify organic
emissions from sewage sludge incinerators. These tests are both complex and expensive. In
addition, these measurements are conducted on a noncontinuous basis, which does not allow the
sewage sludge incinerator operator to make timely corrections to management practices when
emissions exceed regulatory levels.
EPA determined, however, that organic emissions could be controlled by monitoring for
THC instead of monitoring the total emissions of individual organic compounds. EPA tests at
four sewage sludge incinerators (U.S. EPA, 1991f; 1991g; 1991h; 1991i) showed a significant
correlation between the THC concentration measured continuously using a flame ionization
detector and the sum of the concentrations of 21 volatile and semivolatile organic compounds
sampled and analyzed for in each sampling run (see Table 6-1). This relationship is illustrated in
Figure 6-1, where the THC concentration in stack gas is plotted against the sum of the
concentrations of the 21 organic compounds detected in each sample. The full data set on which
Table 6-1 and Figure 6-1 are based appears in Appendix F.
Analysis of the data revealed a strong correlation between THC and total organics, as
measured by the Spearman rank correlation coefficient. A correlation coefficient based on rank
was chosen because a linear relationship between THC and total organics is not required to
determine the strength of the correlation. The results of the analysis show a Spearman
correlation coefficient of 0.85, indicating that changes in THC concentrations are highly
significantly correlated with changes in the sum of the concentrations of the 21 organics.
Furthermore, a regression analysis of the data reveals an R2 of 0.81 (see Figure 6-1).
This figure indicates that 81 percent of the change in the THC concentration is accounted for by
the change in the summation of the volatiles and semivolatiles in the emissions. EPA concluded
6-2
-------
TABLE 6-1
CORRELATION BETWEEN THC AND TOTAL ORGANICS—
SUMMARY EMISSIONS DATA FROM FOUR
SEWAGE SLUDGE INCINERATOR UNITS
Site
1
1
1
1
1
2
2
2
2
2
2
3
3
3
4
4
4
4
4
4
4
4
4
Run
1
2
3
4
5
1
2
3
4
5
6
1
2
3
1
2
3
4
5
6
7
8
9
THC
(ppm)
9.00
16.00
9.00
7.50
8.00
21.10
21.00
34.00
0.90
2.00
21.30
182.00
1.01
1.72
0.91
12.60
12.60
28.20
Total Organics
Otg/m3)
3,171.8
3,918.2
3,230.4
2,343.8
4,242.0
4,591.1
3,726.0
6,950.3
7,558.8
7,423.8
14,265.0
13,930.4
850.6
236.8
12,403.9
3,842.7
13,930.4
828.5
236.8
95.9
776.9
931.4
4,963.5
Source: U.S. EPA, 1991f; 1991g; 1991h; 1991i.
6-3
-------
TABLE 6-1
CORRELATION BETWEEN THC AND TOTAL ORGANICS—
SUMMARY EMISSIONS DATA FROM FOUR
SEWAGE SLUDGE INCINERATOR UNITS
Site
1
1
1
1
1
2
2
2
2
2
2
3
3
3
4
4
4
4
4
4
4
4
4
Run
1
2
3
4
5
1
2
3
4
5
6
1
2
3
1
2
3
4
5
6
7
8
9
THC
(ppm)
9.00
16.00
9.00
7.50
8.00
21.10
21.00
34.00
0.90
2.00
2130
182.00
1.01
1.72
0.91
12.60
12.60
28.20
Total Organics
Otgfci1)
3,171.8
3,918.2
3,230.4
2,343.8
4,242.0
4,591.1
3,726.0
6,9503
7,558.8
7,423.8
14,265.0
13,930.4
850.6
236.8
12,403.9
3,842.7
13,930.4
828.5
236.8
95.9
776.9
931.4
4,963.5
Source: U.S. EPA, 1991ft 1991g; 1991h; 1991L
6-3
-------
FIGURE 6-1
TOTAL HYDROCARBON CONCENTRATION (THC) VS. TOTAL
ORGANICS CONCENTRATION OF VOLATILES AND SEMTVOLATILES
DETECTED IN FOUR SEWAGE SLUDGE INCINERATORS
1=
o
ftj
O
14000 -
12000 -
10000 -
9 8000 -
6000 -
4000 -
2000 -
Correlation Coefficient = 0.81
i
0 4
8 12 16 20 24 28 32
TOTAL HYDROCARBON CONCENTRATION (ppm)
Source: U.S.EPA, 1991f; 1991g; 1991lu 1991L
6-4
-------
that the correlation of THC to the sum of the concentration of volatile and semi-volatile organics
in sewage sludge incinerator emissions is sufficiently high to support the use of THC as a basis
for a regulatory control of organic emissions.
THC is a good surrogate for organics not only because of the significance of the
correlation but also because it is easier and less expensive (excluding capital expenditures) to
monitor for a subset of simple organic compounds than to monitor for total organics, which
include complex compounds. In addition, THC monitoring can be performed continuously with
a flame-ionization detector, which enhances the ability of a sewage sludge incinerator operator to
correct management practices and incinerator operational conditions when THC emissions
exceed regulatory levels. EPA uses carbon monoxide (CO) and THC emissions as a surrogate
for organic emissions in its hazardous waste program. For the case of sewage sludge
incinerators, however, THC is a more appropriate surrogate for organics than CO.
A THC monitor can detect hydrocarbons present in the vapor phase. Unheated (cold)
THC monitors, however, can occasionally fail to detect the higher molecular weight compounds
with low vapor pressure because these compounds condense in the sample line of the monitoring
device, therefore providing an inaccurate measure of the total organic mass emission rate of a
combustion gas. Using a heated monitoring device, which maintains stack outlet temperature,
makes it less likely that those compounds with low volatility will condense in the sampling line
and more likely that they will reach the monitor. Because of this advantage of a heated sampling
line, Subpart E of the sewage sludge regulation requires that THC measurements be taken "hot."
(Section 7.1 discusses in more detail the rationale behind the use of a hot THC monitoring
device.)
EPA test data also indicate that it is impossible to regulate total organics by setting limits
on the concentration of these pollutants in the sewage sludge. To derive an allowable
concentration of organics in sewage sludge would require that a "destruction and removal
efficiency" be established for the organics, similar to the control efficiency derived for the five
metals for which pollutant limits are calculated. This destruction and removal efficiency
approach to controlling organics fails to account directly for emissions of products of incomplete
combustion (PICs), which can be as toxic as, or more toxic than, the principal organic hazardous
6-5
-------
constituents. The data also indicate that, although most organic constituents in the sewage
sludge are readily transformed into nonhazardous substances during the combustion process,
organics in the drying zone of multiple-hearth sewage sludge incinerators are volatilized directly
into the exhaust gases and bypass combustion. For these reasons, a destruction and removal
efficiency approach is not feasible for regulating organics in the sewage sludge. Instead, EPA
decided to use THC as a surrogate for organics and monitor for THC in the stack gas.
6.2 STATUTORY BASIS FOR USING AN OPERATIONAL STANDARD
Section 405 (d) of the Clean Water Act requires EPA to develop regulations for the use
or disposal of sewage sludge that are protective of public health from any reasonably anticipated
adverse effects of the pollutants. In the case of THC, the potential adverse health effects from
excessive exposure to certain organic pollutants may be various forms of cancer and
noncancerous effects.
EPA's original approach to regulating THC, as outlined in the proposed rule, was to
establish a site-specific limit on THC emissions that varied according to the characteristics of the
sewage sludge incinerator and site conditions. EPA derived a standard RSC value for THC from
a THC cancer potency value that was weighted to account for the different cancer potencies of
each carcinogen detected or suspected to be in sewage sludge incinerator emissions.
Comments received on the proposed regulation (U.S. EPA, 1989) suggested that such a
risk-based methodology might produce unrealistic risk estimates and that EPA could not
conclude with certainty that such emission limits calculated from such a methodology were
protective of public health. The Agency concurred with these comments and decided to replace
its proposed THC approach with an operational standard that is technology-based.
The CWA specifically provides for alternatives to numeric limitations for sewage sludge
use or disposal in certain circumstances:
6-6
-------
"Alternative standards — For purposes of this subsection, if, in the judgment of the
Administrator, it is not feasible to prescribe or enforce a numeric limitation for a
pollutant identified under paragraph (2), the Administrator may instead
promulgate a design, equipment, management practice, or operational standard
(emphasis added), or combination thereof, which in the Administrator's judgment
is adequate to protect public health and the environment from any reasonably
anticipated adverse effect of such pollutant." [Clean Water Act, Section 405
EPA has selected a regulatory limit for sewage sludge incinerators of 100 ppm THC
measured with a hot sampling line monitor for three main reasons: (1) it is within the range of
values reported in the Agency's data base for sewage sludge incinerators; (2) based on aggregate
effects risk assessment, there are minimal pollutant effects from current sewage sludge
incineration practices; and (3) based on existing data, the Agency concluded that the limit is
protective of public health at a risk level of 1 x 10"* to an HEI.
6.3 BASIS FOR THC OPERATIONAL STANDARD
Part 503 requires that THC in the stack gas not exceed the 100 ppm THC limit, as
measured with a hot sampling line monitoring device and corrected to 7-percent oxygen and for
zero-percent moisture. Compliance with the monthly average THC operational standard of 100
ppm is determined by calculating the arithmetic mean of the hourly averages for the hours a
sewage sludge incinerator operates during the calendar month. An hourly average is the
arithmetic mean of all THC measurements taken during each operating hour with a minimum of
two measurements taken during the hour. EPA does not require monitoring of organic
pollutants in the sewage sludge, as is required for the metals limits, because organic pollutant
emissions are determined more by the operational characteristics of a sewage sludge incinerator
unit (e.g., combustion temperature, percent excess air) than by their presence in sewage sludge.
EPA based the THC operational standard of 100 ppm on extensive testing at three
sewage sludge incinerators—two multiple-hearth furnaces (MHFs) and one fluidized-bed furnace
(FBFV "me of the MHFs (Site 6) was outfitted with a scrubber but no electrostatic precipitator
(ESP =ile the other MHF (Site 9) had both a Venturi scrubber and a full-scale wet ESP
(WESP;. The FBF (Site 8) was outfitted with a Venturi scrubber and a pilot-scale WESP. The
6-7
-------
MHFs were run under normal operating conditions and improved conditions (e.g., higher
combustion temperatures, optimizing excess air requirements, firing sewage sludge with a lower
water content), and the FBF was run under normal conditions only (U.S. EPA, 1991a; 1991b;
1991c).
The operational standard is based on actual data from the three sites and is not based on
parametric statistical models from which inferences were made. The data for these sites are
summarized in Table 6-2. Measurements performed at all three sewage sludge incinerators were
taken with an unheated ("cold") sampling line monitoring device. At the MHF with a WESP, the
measurements were taken at the outlet from the scrubber, whereas measurements from the MHF
and FBF with WESPs were taken at the outlet from the WESPs.
These data show that for the two MHFs, there is a dramatic difference between the data
obtained under improved operating conditions and those obtained under normal conditions. For
example, at Site 6 under normal operations, the cold sampling line monitor measured 20 ppm
(equivalent to 30-ppm measured with a hot sampling line) or less only 3.9 percent of the time
(3.9th percentile), whereas under improved conditions, emissions of THC remained under 20
ppm 98.6 percent of the time (98.6th percentile). At Site 9, a nearly identical result was
obtained. v
Data obtained from the FBF unit (Site 8) show that much lower THC emission levels can
be expected from this type of sewage sludge incinerator. At the 99th percentile, under normal
operating conditions, the THC emission level was 8.3 ppm measured with a cold sampling line
•
(U.S. EPA, 1992f). For a discussion of these test results see Appendix G.
After evaluating the aggregate impact analysis, which showed that there are minimal
health effects from current sewage sludge incineration practices, along with the site data on THC
emissions, EPA decided to set the THC operational standard at 100 ppm measured with a hot
sampling line. EPA believes that the 100 ppm standard can reasonably be met by most sewage
sludge incinerators without modifying any equipment or operations.
6-8
-------
TABLE 6-2
SUMMARY OF TOTAL HYDROCARBONS EMISSIONS
MEASURED WITH A "COLD" MONITOR AND
ADJUSTED TO 7-PERCENT OXYGEN*
Site
Site 6
SiteS
Site 9
Incinerator
Type
MHF1
FBF2
MHFJ
Operating
Conditions**
Normal
Improved
Normal
Normal
Improved
Number
of Data
Points
909
655
769
1395
1512
PERCENTILE FOR
20 ppm
3.9%
98.6%
100.0%
1.1%
98.8%
25 ppm
10.7%
100.0%
100.0%
4.7%
99.3%
30 ppm
24.0%
100.0%
100.0%
8.0%
99.7%
ppm AT PERCENTILE
90%
63.0
17.7
4.6
390.0
15.9
95%
98.0
18.5
5.1
503.0
17.2
99%
193.0
21.0
8.3
1,194.0
20.3
*Data do not include measurements that have an event flag, such as "plant not operating" or "monitor failure."
* * Improved operating conditions includes higher combustion temperatures, optimizing excess requirements, and firing sewage sludge with
a lower water content.
'MHF with scrubber and no electrostatic precipitator
2FBF with Venturi scrubber and pilot-scale wet electrostatic precipitator
3MHF with Venturi scrubber and full-scale wet electrostatic precipitator
(U.S. EPA, 1992f)
-------
TABLE 6-2
SUMMARY OF TOTAL HYDROCARBONS EMISSIONS
MEASURED WITH A "COLD" MONITOR AND
ADJUSTED TO 7-PERCENT OXYGEN*
Site
Site 6
SiteS
Site 9
Incinerator
Type
MHF1
FBF2
MHFJ
Operating
Conditions**
Normal
Improved
Normal
Normal
Improved
Number
of Data
Points
909
655
769
1395
1512
PERCENTILE FOR
20 ppm
3.9%
98.6%
100.0%
1.1%
98.8%
25 ppm
10.7%
100.0%
100.0%
4.7%
99.3%
30 ppm
24.0%
100.0%
100.0%
8.0%
99.7%
ppm AT PERCENTILE
90%
63.0
17.7
4.6
390.0
15.9
95%
98.0
18.5
' 5.1
503.0
17.2
99%
193.0
21.0
8.3
1,194.0
20.3
o\
*Data do not include measurements that have an event flag, such as "plant not operating" or "monitor failure."
** Improved operating conditions includes higher combustion temperatures, optimizing excess requirements, and firing sewage sludge with
a lower water content.
'MHF with scrubber and no electrostatic precipitator
2FBF with Venturi scrubber and pilot-scale wet electrostatic precipitator
3MHF with Venturi scrubber and full-scale wet electrostatic precipitator
(U.S. EPA, 1992f)
-------
As noted earlier, Subpart E of the sewage sludge regulation requires that THC be
monitored using a heated sampling monitoring device. Because measurements at the three
sewage sludge incinerators were taken using an unheated (cold) sampling line technique, further
tests were conducted to develop a conversion factor. Based on extensive data from a fourth
MHF (Site 4), where emissions were measured using both a heated and unheated (cold)
sampling line THC analyzer, EPA determined that the difference between measurements
conducted using a hot sampling line analyzer and those measured with a cold sampling line
monitor was 10 ppm at the 90th percentile (U.S. EPA, 1992g).
Emission samples were taken using both hot and cold sampling line THC analyzers at the
inlet to the Venturi scrubber after the gas exited the afterburner. EPA developed two basic
criteria by which to choose data to use in developing the conversion factor between hot and cold
THC analyzer measurements. First, the THC measurements had to be performed simultaneously
using hot and cold sampling line analyzers. Second, the measurements had to be for emissions
near or below the regulatory level of 100 ppm hot. The data meeting these criteria were used to
develop the conversion factor.
In general, hot and cold sampling line THC measurements taken when emissions are near
the regulatory level (100 ppm hot) differ less than those taken at higher emission levels. This
result occurs because unheated sample lines condense a fraction of the volatile organics. Thus,
the absolute difference between THC measured hot and cold will increase as the emission level
increases. For a discussion of these test results, see Appendix H.
6.4 CORRECTION FACTORS FOR OXYGEN AND MOISTURE CONTENT AND A
SAMPLE CALCULATION FOR THC CONCENTRATION
Subpart E requires that measurements of THC emissions from a sewage sludge
incinerator be corrected to account for the actual moisture content and amount of oxygen
present in the combustion gases. Stoichiometric air is the amount of air that contains the
amount of oxygen needed to completely combust the organic fraction in the combustion chamber
(see Section 2.2.1). "Excess air" is the amount of air in the combustion chamber in excess of the
6-10
-------
stoichiometric air requirement. The introduction of extra oxygen, or excess air, into the
combustion chamber enhances the combustion process. The use of excess air is also a
management practice employed by sewage sludge incinerator operators to account for variations
in the system, including the sewage sludge feed rate and the sewage sludge moisture content.
The Subpart E requirement that THC measurements be corrected to 7-percent oxygen
stipulates that the measurements be calculated assuming that 7 percent more oxygen is being
introduced into the combustion chamber than is needed to fully combust the organic material.
The 7-percent oxygen value is the standard amount of oxygen used to reference measurements
required for pollutant limits expressed as a concentration (i.e., ppm) rather than as an emission
rate (i.e., /ig/m3), and 7-percent oxygen in the combustion gas is equivalent to 50-percent excess
air. It is also the amount of oxygen used by most efficient combustion processes to enhance
combustion. However, any percentage of oxygen could have been chosen as long as all THC
measurements were corrected to that value.
If the THC measurement were not corrected to 7-percent oxygen or some other standard,
sewage sludge incinerators could lower the THC concentration detected without reducing the
actual emission rate of THC simply by adding higher rates of air to the incinerator. High oxygen
rates dilute the THC concentration detected by the flame-ionization detector and could allow an
incinerator to appear to be meeting the THC standard, when actually the THC emissions are in
excess of those set by the standard.
Subpart E also requires that THC measurements be based on zero-percent moisture for a
similar reason as that for the 7-percent oxygen requirement. Moisture can dilute THC
measurements similar to excess air. Since most sewage sludges are composed of a significant
percentage of water, the THC measurement must be based on an unchanging moisture content.
THC is measured conventionally in terms of a dry-volumetric basis, so zero percent is used for
the moisture content.
Subpart E requires that both the moisture content and the oxygen concentration in stack
gas be corrected so that THC emissions can be compared to an operational standard. As
discussed in Section 7.1, THC emissions are initially measured using a flame ionization detector.
6-11
-------
This THC reading will contain a certain percentage of moisture. Equation 1 below corrects this
THCwet concentration to zero-percent moisture (THC^). The percent moisture concentration in
the stack gas is determined in two ways depending on whether the THC measurements are taken
in saturated conditions (100 percent relative humidity) or non-saturated conditions (see Section
7.3).
= THC^/1-X (1)
where:
THC^ = ppm THC corrected to zero-percent moisture
THCwet = ppm THC measured with a flame ionization detector
X = percent moisture content, in hundredths (volume/volume)
The THC^ calculation from Equation 1 is input into Equation 2 below, along with the
percent oxygen concentration, to determine the THC concentration at 7-percent oxygen and
zero-percent moisture. The percentage of oxygen in the stack gas is measured by an oxygen
monitor (see Section 7.2).
= THC^x 14/21- Y (2)
where:
THQ»rrected = PPm THC corrected to zero-percent moisture and 7-percent
oxygen
= ppm THC corrected to zero-percent moisture
21 = the percent of oxygen in air, rounded
14 = the difference between the percent of oxygen in air (21 percent)
and 7 percent oxygen
Y = percent oxygen concentration in the sewage sludge incinerator
stack exit gas (dry volume/dry volume)
The sample calculation below uses hypothetical data in Equations 1 and 2 to derive a
THCcorrected value that would be compared to the 100 ppm THC standard to determine
6-12
-------
compliance. The assumptions below are for THC measurements taken in the stack gas exiting a
wet scrubber, where saturated conditions are assumed to be present (see Section 7.3).
Sample Calculation Assumptions:
THCwet = 40ppm
stack gas temperature = 120°F (49°C).
percent moisture = .12 (in hundredths)
percent oxygen = 10 (actual percent)
THCwet/l - X
40 ppm/1 - .12
45.5 ppm
THCmmcted = THC^ X 14/21 -
45.5 ppm X 14/21 - 10
= 58 ppm
6.5 RISK POSED BY THE THC OPERATIONAL STANDARD
As mentioned in Sections 6.2 and 6.3, EPA based the 100 ppm THC standard on sewage
sludge incinerator technology and not risk assessment methodology. Even so, EPA assessed the
THC operational standard for risk to judge whether the THC operational standard is protective
of public health at a 10"* risk level to an HEI. EPA performed its risk assessment using the 100
ppm THC emission standard and data on 23 POTWs operating sewage sludge incinerators
obtained from the National Sewage Sludge Survey (NSSS). The results of the analysis showed
that the risk associated with emissions at a 100 ppm THC level at all 23 plants were calculated to
be lower than the 10"4 risk level, which is at the upper end of the Agency's allowable risk. The
remainder of this section describes how EPA used risk assessment methodology to judge the risk
to an HEI posed by the THC operational standard.
6-13
-------
6.5.1 Equations Used to Determine the Degree of Risk
To evaluate the risk posed by the THC operational standard, EPA used two equations,
the first of which (Equation 2) calculates an RSC value for THC based on the 100 ppra emission
standard, two site-specific variables pertaining to characteristics of a sewage sludge incinerator,
and a conversion factor. The RSC is then input into a second equation (Equation 3) used to
conduct a risk assessment to determine the degree of risk posed by the THC emission standard
under the site-specific conditions. Twenty-three risk assessments were conducted, one for each
POTW operating sewage sludge incinerators for which complete data were available in the NSSS
data base. Table 6-3 lists each of the 23 sewage sludge incinerators in the NSSS along with the
calculated dispersion factor, gas flow rate (see Section 6.6.2), and risk level. In no case did the
risk level exceed 10"4. (For more information on how the dispersion factors were calculated, see
U.S. EPA, 1992h; Hughes 1991.) These POTWs are statistically representative of all POTWs
operating sewage sludge incinerators nationwide. The risk level calculated for each incinerator
was compared to the 10"4 risk level. Equations 2 and 3 are presented below:
RSC = THC x DP x GF (2)
* 3.24 x 109
where:
RSC^ = site-specific risk-specific concentration for THC, in micrograms per
cubic meter (/xg/m3).
THC = operational standard for THC in the sewage sludge incinerator
emissions, in parts per million, on a volumetric basis, corrected for
7-percent oxygen and zero-percent moisture (dry basis) (ppm).
DF = dispersion factor (the ratio of the increase in ground-level air
concentration at or beyond the property line to the mass emission
rate for the pollutant from the stack), in micrograms per cubic
meter, per gram, per second (ftg/m3/g/sec).
GF = maximum combustion gas flow rate from the sewage sludge
incinerator, in gram-moles per day (g-moles/day).
3.24 x 10* = combination of conversion factors that express the RSC value as a
volumetric concentration.
6-14
-------
TABLE 6-3
RISK LEVELS AND OTHER DATA FOR 23 SEWAGE SLUDGE INCINERATORS
CALCULATED FROM DATA PROVIDED BY THE
1988 NATIONAL SEWAGE SLUDGE SURVEY
(Based on 100 ppm THC)
Site
212
221
317
319
351
Oil
040
051
072
076
157
172
181
209
210
214
244
287
Incinerator
Type
MHF
MHF
MHF
MHF
MHF
MHF
MHF
MHF
EF
MHF
MHF
MHF
MHF
FBF
MHF
MHF
MHF
MHF
Air Pollution
Controls
Scrubber
Scrubber,
Afterburner
w/Heat Exch.
Scrubber,
Afterburner
w/Heat Exch.
Scrubber
Scrubber,
Afterburner
w/Heat Exch.
Scrubber,
Afterburner
Scrubber
Scrubber
Scrubber
Scrubber
Scrubber,
Afterburner
w/Heat Exch.
Scrubber
Scrubber
Scrubber
Scrubber,
Afterburner
Scrubber
Scrubber
Scrubber,
Afterburner
Dispersion
Factor
Oig/mVg/sec)"1
0.42
1.37
4.02
14.27
0.30
9.19
6.89
3.26
23.43
0.79
1.26
6.92
0.76
23.80
1.26
2.66
8.86
3.27
Gas Flow
Rate
(g-moles/day)
191,785,257
137,339,818
31,690,611
25,594,905
29,090,531
16,606,051
6,493,943
7,979,586
19,360
19,579,456
4,908,786
4,781,872
17,727,979
3,747,667
3,002,822
31,297,383
1,853,342
8,327,339
Risk-Specific
Concentration
(jig/m1)
2.49
5.81
3.93
11.27
0.27
4.71
1.38
0.80
0.01
0.48
0.19
1.02
0.42
2.75
0.12
2.57
0.51
0.84
Risk Level
8.52E-06
1.99E-05
1.35E-05
3.86E-05
9.34E-07
1.61E-05
4.73E-06
2.75E-06
4.80E-08
1.64E-06
6.55E-07
3.50E-06
1.43E-06
9.44E-06
4.00E-07
8.81E-06
1.74E-06
2.88E-06
6-15
-------
. ,.
* BW x 103
where:
= site-specific risk level, or the probability of developing cancer,
unitless
= site-specific risk-specific concentration for THC, in micrograms per
cubic meter (/ig/m3)
q,* = weighted cancer potency value for THC, in milligrams per
kilogram-day (mg/kg-day)"1
Ia = inhalation rate, in cubic meters per day (mVday)
BW = body weight, in kilograms (kg)
103 = conversion factor from raicrograms to milligrams (1,000 /xg/mg)
6.5.2 Derivation of Estimated Site-Specific RSC Values for THC
Unlike the pollutant limit calculations for the five metals that use a risk-based equation,
the THC risk assessments require that site-specific RSC values be calculated for each sewage
sludge incinerator (which may include one or more sewage sludge incinerator units). RSCs are
then used to calculate site-specific risk levels. As Equation 2 shows, these THC RSC values are
based on four factors: the THC operational standard, the dispersion factor, the gas flow rate,
and a conversion factor. The derivation of the THC operational standard of 100 ppm measured
with a heated monitor was described in Section 6.3. This section describes the derivation of the
site-specific calculations for the dispersion factor and the gas flow rate and provides an
explanation for the conversion factor.
6-17
-------
TABLE 6-3 (cont.)
Site
314
447
084
353
149
Incinerator
Type
MHF
MHF
FBF
MHF
FBF
Air Pollution
Controls
Scrubber
Scrubber
Scrubber
Scrubber
Scrubber
Dispersion
Factor
Gig/m'/g/sec)'1
31.20
2.29
26.58
3.41
8.80
Gas Flow
Rate
(g-moles/day)
3,073,146
14,983,785
7,916,493
1,746,395
4,695,776
Risk-Specific
Concentration
Gug/m3)
2.92
1.29
6.49
0.18
1.28
Risk Level
l.OOE-05
4.42E-06
2.23 E-05
6.30E-07
4.37E-06
Note: EF = Electric Furnace
FBF = Fluidized Bed Furnace
MHF = Multiple Hearth Furnace
Source: ERG estimates based on 1988 National Sewage Sludge Survey, EPA.
6-16
-------
The derivation of the annual average daily fuel usage rate (FR) involves an extensive calculation.
The formula for this calculation, including related assumptions and data, can be found in
Appendix J.
To derive the fuel constant for #2 fuel oil (FC), the following factors were used:
FC
r^
FC
#2 oil
18,300 Btu/lb x 7.5 lb/air/10,000 Btu x 1.50 x 1 g-mole air/28.84 g
air x 453.6 g-mole /lb-mole
323.80
where:
18,300
7.5 Ib/air
10,000 Btu
1.50
28.84
453.6
average heating value of #2 fuel oil, in Btu/lb
stoichiometric air requirement for
combustion of fuel oil
50 percent excess air rate (7-percent oxygen)
molecular weight of air
conversion from Ib-moles gas to g-moles gas
The equations above are based on standard combustion parameters, data on the sewage
sludge, and data on the amount of auxiliary fuel used. The calculation provides an estimate of
the total gas flow on a dry weight basis at 7-percent oxygen, the same amount of excess air as is
required in the regulation. The gas flow rates have been calculated for the 23 sewage sludge
incinerators in the NSSS and appear in Table 6-3.
6.52.3 Conversion Factor
The THC emission value is converted to a volumetric basis for consistency with the THC
analyzer that also monitors on a volumetric basis. To convert the THC concentration into an
emission rate, a series of conversion factors were required. The following factors have been
combined to form the conversion factor of 3.24 x 10':
6-20
-------
* BW x 103
where:
= site-specific risk level, or the probability of developing cancer,
unitless
RSC,p = site-specific risk-specific concentration for THC, in raicrograms per
cubic meter (fig/m3)
qx* = weighted cancer potency value for THC, in milligrams per
kilogram-day (mg/kg-day)"1
I, = inhalation rate, in cubic meters per day (m3/day)
BW = body weight, in kilograms (kg)
103 = conversion factor from raicrograms to milligrams (1,000 /ig/mg)
Derivation of Estimated Site-Specific RSC Values for THC
Unlike the pollutant limit calculations for the five metals that use a risk-based equation,
the THC risk assessments require that site-specific RSC values be calculated for each sewage
sludge incinerator (which may include one or more sewage sludge incinerator units). RSCs are
then used to calculate site-specific risk levels. As Equation 2 shows, these THC RSC values are
based on four factors: the THC operational standard, the dispersion factor, the gas flow rate,
and a conversion factor. The derivation of the THC operational standard of 100 ppm measured
with a heated monitor was described in Section 6.3. This section describes the derivation of the
site-specific calculations for the dispersion factor and the gas flow rate and provides an
explanation for the conversion factor.
6-17
-------
633.1 Dispersion Factor
EPA calculated dispersion factors for the 23 sewage sludge incinerators in the NSSS data
base based on site-specific factors. The air dispersion model used to calculate the dispersion
factors was the Industrial Source Complex Long-Term (ISCLT2) model (see Section 5.6.1).
652.2 Gas Flow Rate
The flame-ionization detector (FID) measures THC emissions in terras of a gas
concentration (ppm, volume) (ppmv). To obtain an RSC value for THC, which is measured as a
ground-level air concentration, an allowable emission rate must be calculated. To make the
conversion, the total gas flow in the sewage sludge incinerator stack must also be calculated.
Once the gas flow rate is known, the mass emission rate can be calculated. The dispersion factor
is then used to convert the THC mass emission rate to a ground-level ambient-air concentration
(the RSC). The equation used to calculate the gas flow rate is:
OF = SOF + POP (4)
where:
GF = maximum combustion gas flow rate from the sewage sludge incinerator, in
gram moles per day (g-moles/day)
SGF = maximum combustion gas flow rate attributable to the combustible portion
of the sewage sludge, in gram moles per day (g-moles/day)
FGF = fuel combustion gas flow rate, in gram moles per day (g-moles/day)
Calculating the maximum combustion gas flow rate from the sewage sludge incinerator is
a two-step process. Listed below are the factors used to calculate the two parts of the gas-flow-
rate equation. In each step, the factors are explained and the units in which the factor is
expressed are presented. Included in the explanation is whether, for the purposes of these
6-18
-------
calculations, the factor was assumed to be a certain value or whether the data were site-specific
and obtained from the NSSS.
Step 1 — Calculate the maximum combustion gas flow rate for the sewage sludge
incinerator attributable to the combustible portion of the sewage sludge using Equation 5:
SGF = SF x VF x VEHC x 7
-------
The derivation of the annual average daily fuel usage rate (FR) involves an extensive calculation.
The formula for this calculation, including related assumptions and data, can be found in
Appendix J.
To derive the fuel constant for #2 fuel oil (FC), the following factors were used:
FC
#2 oil
FC
#2 oil
18,300 Btu/lb x 7.5 lb/air/10,000 Btu x 1.50 x 1 g-raole air/28.84 g
air x 453.6 g-mole /lb-mole
323.80
where:
18,300
7.5 Ib/air
10,000 Btu
1.50
28.84
453.6
average heating value of #2 fuel oil, in Btu/lb
stoichiometric air requirement for
combustion of fuel oil
50 percent excess air rate (7-percent oxygen)
molecular weight of air
conversion from Ib-moles gas to g-moles gas
The equations above are based on standard combustion parameters, data on the sewage
sludge, and data on the amount of auxiliary fuel used. The calculation provides an estimate of
the total gas flow on a dry weight basis at 7-percent oxygen, the same amount of excess air as is
required in the regulation. The gas flow rates have been calculated for the 23 sewage sludge
incinerators in the NSSS and appear in Table 6-3.
6523 CoifMrnbn Factor
The THC emission value is converted to a volumetric basis for consistency with the THC
analyzer that also monitors on a volumetric basis. To convert the THC concentration into an
emission rate, a series of conversion factors were required. The following factors have been
combined to form the conversion factor of 3.24 x 10':
6-20
-------
86.400 x 0.75 x 1.7 x (1 x 106) = 3 ^ x ^ (7)
34
where:
86,400 = conversion from seconds to days (86,400 sec/day)
0.75 = factor to adjust for the estimated loss of heavy organics in the sampling
system (dimensionless)
1.7 = ratio of the FID response factor of propane (3.0) to the weighted average
FID response of the list of compounds (1.8) used to determine the
weighted cancer potency (qt*) for THC (see Section 6.6.3.1)
1 x 106 = conversion of concentration to ppm
34.0 = sum of the weighted molecular weight of the THC compounds used to
develop the qt* (g-moles)
The response factor accounts for the response of the FID monitor to the substance it is
monitoring. The FID measures the number of chemical bonds per molecule being broken.
Because each organic compound has a different set of chemical bonds, the response factor is
different for each compound. To correct for the varying responses, each measurement is
referenced to propane, which has a standard response factor of 3.0. The response factor of 1.8 is
the weighted average response factor for total organics used to develop the weighted qt*, which
is discussed in Section 6.6J.1. The 1.7 constant is the ratio of the FID response factor of
propane (3.0) to the average response factor for total organics (1.8). For a complete list of the
response factors for the qt* organics, see Appendix I.
The 34.0 g-moles represents the average molecular weight of the organic compounds used
to develop the q,* for THC. These values also are listed in Appendix I.
6-21
-------
6JJ.4 Example of a Calculation to Derive a Site-Specific RSC Value
The following is a simplified calculation to obtain the site-specific RSC value for THC
using data from one of the 23 sewage sludge incinerators listed in the NSSS (POTW 317). For
the full calculations using data for all 23 POTWs, see Appendix I.
RSC .= THCxDFxGF
* 3.24 x 109
where:
RSC,,, = site-specific risk-specific concentration for THC, in /ig/m3
THC = operational standard for THC in the sewage sludge incinerator
emissions, in parts per million, on a volumetric basis, corrected for
seven percent oxygen (dry basis) = 100 ppm.
DF = dispersion factor = 4.02 (/ig/m3/g/sec)
GF = maximum combustion gas flow rate = 31,690,610 g-moles/day
3.24 x 10' = combination of conversion factors that express the RSC value as a
volumetric concentration
The actual calculation then is:
RSC,, = (100 ppm) x (4.02 (|ig/m3/g/sec)) x (31,690,610 g-moles/day)/3.24 x 109
= 3.93 ug/nf
6.5.3 Estimate of Public Health Protection Regarding the THC Operational Standard
As described earlier in this section, the RSC for THC was developed solely to judge
whether the 100 ppra operational standard for THC measured at the stack was protective of
public health to the 10"* risk level. The RSC was not used to develop the technology-based 100
ppm standard. The equation used to judge the risk posed by the THC standard was presented
6-22
-------
earlier in Section 6.6.1 (Equation 3). The only factor in this equation that has not been
explained is the cancer potency value (q^). The derivation of a weighted q,* value for THC is
described below.
6.5.3.1 Derivation of a Weighted Cancer Potency Value for THC
The THC cancer potency value (q/) is representative of all organic compounds emitted
from a sewage sludge incinerator that have the potential to create an adverse health effect. EPA
considers two types of compounds that create adverse health effects—carcinogens and
noncarcinogens. For carcinogens, the level of exposure determines the anticipated cancerous
effect. For toxic compounds not known to have carcinogenic properties, EPA sets a threshold
concentration below which no adverse health effects are known to occur. To protect against the
adverse health effects of a noncarcinogen, the concentration should be kept below the threshold
dose.
The qt* value for THC was calculated using data on 21 compounds detected in tests at
eight sewage sludge incinerators, as well as on data for numerous organics that were potentially
present but not detected in the tests. The complete list of organics used to develop the q^ value
for THC is presented in Appendix K. The list of organics includes the following compounds:
• 21 carcinogenic and noncarcinogenic compounds detected in tests at 8 sewage
sludge incinerators (U.S. EPA, 1991a-c,f-j)
• All carcinogens and noncarcinogens for which inhalation health effects data are
found in EPA's Integrated Risk Information System (IRIS), but which were not
detected in the sewage sludge incinerator tests. (IRIS is EPA's database of
chemical risk assessment information.)
• Formaldehyde, which has been detected in the emissions of municipal waste
incinerators, and chloromethane, detected in hazardous waste incinerators, but
which were not measured during the sewage sludge incinerator emissions tests.
• Methane (Ct) and ethane, ethylene, and acetylene (Q), which are known to be
emitted in significant quantities from all combustion sources, but which were not
measured during the sewage sludge incinerator tests.
6-23
-------
Each organic chemical listed in Appendix K has a corresponding q,*, an emission
concentration, a weighted fraction based on the emission concentration, and a weighted q,*
value. The q,* for THC is derived by adding the weighted qj* values for each compound on the
list. For carcinogens, the individual q,* values are obtained directly from the IRIS database.
Noncarcinogens, however, have zero carcinogenic potency and thus are represented by zeros in
the first column of Appendix K (U.S. EPA, 1991k).
For the noncarcinogens, EPA has identified exposure thresholds below which adverse
health effects usually do not occur. Therefore, protection against the adverse health effects of a
noncarcinogen is likely to be achieved by preventing total exposure levels from exceeding the
threshold dose. EPA uses these threshold values to calculate reference air concentrations
(RACs) for noncarcinogenic compounds much as cancer potency values are used to develop
RSCs for carcinogens. RACs are defined in terms of a fixed fraction of the estimated threshold
concentration. To develop the qt* for THC, EPA has assumed that the actual maximum ambient
air concentrations for each compound will not exceed the RACs and, therefore, would not cause
adverse health effects. EPA makes this assumption because all noncarcinogenic compounds
detected in the sewage sludge incinerator tests were below the threshold levels. EPA, therefore,
assumed that those noncarcinogenic compounds not detected were at the detection limit for the
monitoring equipment, which is also below the threshold levels for each compound. Although
noncarcinogens do not affect the q,* value for THC, these compounds are listed in Appendix K
to account for their contribution to the total mass of organic emissions.
The second column in Appendix K lists each compound's emission concentration. For
each of the 21 detected compounds, EPA used the 95th percentile concentration to develop the
q,* value. If a compound was only detected once, the single-point concentration was used. The
available data used to obtain the emission concentrations for the 21 detected compounds can be
found in Appendix L. For the nondetected organics taken from the IRIS database, EPA used an
assumed detection limit of 0.1 /tg/m3. Although these compounds were not detected in emissions
from the sewage sludge incinerators tested, they have been detected during a variety of other
EPA combustion tests. Concentrations for formaldehyde and chloromethane are based on data
from tests of municipal solid waste and hazardous waste incinerators, respectively. In addition,
to account for the presence of the Ct compound (methane) and the C2 compounds (ethane,
6-24
-------
ethylene, and acetylene) known to be emitted in stack gases, EPA used combustion data from
fossil-fueled boilers, furnaces, and other sources. The Agency used the 95th percentile
concentrations of the Cj and C2 fractions in the q,* calculation. These 95th percentile
concentrations are shown at the end of Appendix K.
The third column in Appendix K is the weighted fractional concentration for each
compound based on the compound's detected or assumed concentration. The last column, the
weighted qt*, is derived by multiplying the qt* value for each compound (zero for
noncarcinogens) by its weighted fractional concentration. The qt* for THC, which is the result
of the addition of these weighted q^ values, is calculated to be 1.2 x 10'2 (U.S. EPA, 1991k).
6.5.3.2 Example of a Calculation Used to Evaluate the Risk Level for the THC Operational
Standard
The following is an example of a calculation used to evaluate risk level for THC
emissions using data from one of the 23 sewage sludge incinerators listed in the NSSS (POTW
317) and the 100 ppm THC operational standard, measured with a hot sampling line and
corrected to 7-percent oxygen. The risk levels for all 23 POTWs appear in Appendix J. The
results of the calculations show that the risk levels for all 23 POTWs are at or lower than the
10"4 risk level established in Subpart E of the Part 503 rule to protect public health. Based on
these results, in the Administrator's judgment, the THC operational standard is protective of
public health to the 10"4 risk level. Below is the sample calculation:
RL . --T«V«fc
* BW x 103
where:
= site-specific risk level, or the probability of developing cancer, unitless
= site-specific risk-specific concentration for THC = 3.93 /ig/m3
q,* = weighted cancer potency value for THC = 1.2 x 10~2 (mg/kg-day)"1
I, = inhalation rate = 20 m3/day
6-25
-------
BW = body weight = 70 kg
103 = conversion factor = 1,000
The actual calculation then is:
= (3.93 mg/m3) x (1.2 x 10'2 (mg/kg-day)'!) x (20 m3/day)
70 kg x 1,000 mg/mg
= US x ID"5
6-26
-------
SECTION SEVEN
MANAGEMENT PRACTICES
Under Subpart E, data must be measured and recorded to determine compliance with the
pollutant limits and operational standard. Key operating parameters for sewage sludge
incinerators are monitored continuously to indicate that adequate combustion conditions are
being maintained in the incinerator and to minimize metal and THC emissions. The regulation
requires the use of four instruments to continuously measure and record the following data for
each sewage sludge incinerator: the THC concentration in the stack exit gas; the oxygen
concentration in the stack gas; information used to determine the moisture content in the stack
gas; and combustion temperature. The management practices specify that the four monitoring
instruments be installed, calibrated, operated, and maintained, as specified by the permitting
authority. (See the text of the rule in Appendix A.)
7.1 INSTRUMENT FOR MEASURING TOTAL HYDROCARBONS IN STACK GAS
THC is monitored continuously in a sewage sludge incinerator as an indirect indicator of
combustion efficiency for organic compounds in sewage sludge. Subpart E requires that the
instrument measuring THC employ a flame ionization detector (FID). The FTD detects
hydrocarbon emissions in the stack gas and reports the results as a concentration of THC. The
instrument reads out in parts per million of THC by volume. Thus, as described in Section
6.6.2.3, the THC emission rate in grams per second must be converted to a volumetric basis for
consistency with the output of the FID. While THC sampling and detection are continuous, the
data readout can either be on a continuous basis or computer averaged over an established
interval.
The FID is a hydrogen-oxygen flame into which a small sample of exhaust gases from an
incinerator is introduced. If any hydrocarbon compounds are present in the sample, they will be
burned in the flame. When carbon-carbon (C-C) or carbon-hydrogen (C-H) bonds are broken
7-1
-------
and oxidized in the flame, an ion is released and an electrical detection system senses the release
of the ion. The electrical signal strength is thus a direct measure of the number of C-C and C-H
bonds being oxidized in the flame. By using a series of calibration gases of known hydrocarbon
concentration that are periodically introduced into the sample stream, the direct readout of this
signal can be calibrated to indicate the THC concentration in the sample stream.
An FID detector that determines the THC concentration in a stack exit gas 'can also be
viewed as an auxiliary incinerator (afterburner). If there are few THCs in the sampled gas from
the sewage sludge incinerator that bum in the detector, the incinerator is an efficient combustor.
A high level indicates that the incinerator is operating inefficiently.
One problem in interpreting the FID response to an organic compound is that the FID
only measures and "counts" the number of chemical bonds being broken. Thus, a molecule with
a total of 12 C-C and C-H bonds, for example, will respond differently from a molecule that
contains 16 C-C and C-H bonds. A given mass of benzene, in other words, will respond
differently from the same mass of 2,3,7,8-TCPD (tetrachlorinated paradioxin). The FID
therefore provides no direct information about the chemical nature of the molecule being
bumed. Rather, it provides information only about the number of the bonds.
The differing FID responses to organic compounds is expressed as a series of response
factors. Subpart E requires that the output from a detector be expressed as an equivalent ppm
of propane as the calibration gas and that the response factor be referenced to a particular gas
equivalent. The regulation requires that the THC monitor be calibrated at least once every 24
hours and be referenced to propane. As an example, published response factors range from 10
percent for carbon tetrachloride to 225 percent for acetylene when referenced to methane, set at
100 percent. Thus carbon tetrachloride provides a response one-tenth that of methane, and
acetylene produces a response over two times that of methane.
To account for this varying response by the FTD, the Agency has calculated a weighted-
average response factor (see Section 6.6.2.3) similar to the way the cancer potency weighted
average qj* was developed for THCs (see Section 6.6.3.1). The FID response factor is used to
7-2
-------
correct the reading from the FID to account for the same mix of organics used to determine the
Subpart E also requires that the sampling line to the THC monitor be maintained at a
temperature of 150°C. Heated sample lines produce a better correlation between the
concentration of THC and the total organic compounds in the stack gas than do unheated (cold)
sample lines. Cold sampling line monitors condense a fraction of the organics in the sampling
system before they can pass by the FID and, thus, this system does not detect as many
compounds as do the heated devices.
7.2 INSTRUMENT FOR MEASURING OXYGEN CONCENTRATION IN STACK GAS
7.2.1 Excess Air Rate
Oxygen in the exit gas is monitored continuously in a sewage sludge incinerator and is
used to correct the THC emissions measured with an FID to 7-percent oxygen (see Section 6.5).
It is also an indirect indicator of gas velocity in the incinerator and is directly related to excess
air. The excess air rate in a sewage sludge incinerator affects the level of metal emissions. A
high excess air rate, measured as a high percentage of oxygen in the combustion gas, indicates
that more air is being introduced into the combustion than is needed to achieve complete
combustion. This extra air increases the volume of gas passing through the combustion zone,
which increases the velocity of combustion gas as it comes in contact with burning sewage sludge.
The higher gas velocity tends to carry larger quantities of partially burned sewage sludge panicles
and ash particles out of the incinerator and into the APCD. The extra load of combustion gas,
with increased amounts of sewage sludge and ash particles, produces greater post-APCD
emissions.
Conversely, an excess air rate that is too low can cause incomplete combustion of the
organic constituents in the sewage sludge because of insufficient oxygen in parts of the
combustion zone. Continuously monitoring THCs in the stack and limiting the THC
7-3
-------
concentration to 100 ppm, however, precludes the need to specify a minimum excess air level to
ensure complete combustion. If a sewage sludge incinerator is operated at an excess air level too
low to obtain complete combustion, then the THC concentration will exceed the operational
standard and the operator will be forced to increase the excess air to lower the THC level to the
100 ppm limit specified in the permit.
7.2.2 Oxygen Monitors
Oxygen monitors are of two types: in situ and extractive. In situ monitors are in direct
contact with the gas stream. In an extractive system, the gas sample is continuously withdrawn
(extracted) from the gas stream and directed to an analyzer, which may be located several feet or
several hundred feet away.
Extractive analyzers include a conditioning system to remove dust and moisture from the
gas sample; thus, the oxygen concentration measurement is on a dry basis. In situ analyzers, on
the other hand, do not include a conditioning system, and the oxygen concentration measurement
is on a "wet basis." For the same gas stream, the oxygen measurement obtained with an in situ
analyzer will be slightly lower than that obtained with an extractive analyzer. For example, a
typical combustion gas stream that contains 10 percent water vapor will yield a reading of 8
percent oxygen using an in situ analyzer and a reading of 10 percent oxygen using an extractive
analyzer. The oxygen values for sewage sludge incinerators must be reported on a dry basis.
Oxygen analyzers are accurate to +/-1 percent as long as the actual gas to be sampled
reaches the analyzer (no pluggage or in-leakage of air); the conditioning system (if one is
present) is operating properly; and the instrument is calibrated. Electrocatalytic in situ monitors
have rapid response time (i.e., seconds). The response times for polarographic and paramagnetic
extractive analyzers are slower (several seconds to a minute). Extractive systems inherently
involve longer response times, usually on the order of 1 to 2 minutes, depending on the sampling
rate and the volume of the sampling line and conditioning system.
7-4
-------
Problems with oxygen analyzer systems may be difficult to diagnose since they commonly
are associated with slowly developing pluggage in the system or small air in-leaks. The extractive
systems should be checked daily by the operators and maintained and calibrated on a weekly
basis by the sewage sludge incinerator instrument personnel.
73 MEASURING MOISTURE CONTENT IN STACK GAS
The moisture content of the sewage sludge incinerator stack gas is measured for much
the same reason that the percentage of oxygen is determined. Just as excess air, or oxygen, can
dilute a pollutant concentration in a given volume of gas, excess moisture also has a dilatory
effect. For this reason, the moisture content is corrected for all sewage sludge incinerators.
Subpart E requires that the permitting authority specify the appropriate instrument to
continuously measure and record information used to determine the moisture content in the
stack gas, and that an instrument be installed, calibrated, operated, and maintained for each
sewage sludge incinerator.
Where saturated conditions are known to exist, such as in gas exiting a wet ESP or wet
scrubber, the simplest method to determine moisture content is to use a new or existing
thermocouple to measure stack gas temperature. This temperature reading is assumed to
correspond to 100 percent relative humidity because of the wet environment. The stack gas
temperature is then correlated to the moisture content of the stack gas by using a standard
conversion graph (see Figure 7-1). The temperature of most exit gases in typical wet scrubber
systems will be between 110°F and 170°F (43°C and 77°C) which corresponds to a moisture
content of between 10 percent and 40 percent on a volumetric basis. (For a discussion of how
the percent moisture content is used to correct the THC measurement, see Section 6.5.)
Where non-saturated conditions exist, such as where the gas exits a baghouse or dry ESP,
the simplest method to obtain the stack gas moisture content is to use a dewpoint detector (also
called a wet bulb/dry bulb detector). Such an instrument detects the stack gas temperature in a
simulated saturated gas condition. The instrument automatically calculates the stack gas
7-5
-------
FIGURE 7-1
SATURATED WATER VAPOR CONTENT OF FLUE GAS
60 80 100 120 14) 160
GAS TEMPERATURE (°F)
Basis: Volume of water vapor in saturated air at 1 atm.
180
200
220
Source: MITRE, 1983.
7-6
-------
FIGURE 7-1
SATURATED WATER VAPOR CONTENT OF FLUE GAS
60 80 100 120 140 160
GAS TEMPERATURE (°F)
vV Basis: Volume of water vapor in saturated air at 1 aim.
180
200
220
Source MITRE, 1983.
7-6
-------
moisture content from the "dewpoint temperature" in much the same way as the table was used
to determine moisture content where saturated conditions are present.
7.4 COMBUSTION TEMPERATURE
Temperatures in sewage sludge incinerators affect the emissions of both organic
compounds and metals. The regulation requires the maximum combustion temperature for the
sewage sludge incinerator to be consistent with values determined through a performance test.
Excess temperatures increase the volatilization of the metal pollutants from the sewage sludge
solids and increase their emission. Excessively high temperatures also damage equipment and
result in increased maintenance costs. Combustion temperatures that are too low cause
incomplete combustion of organic compounds and promote the formation of products of
incomplete combustion (PICs), both of which are emitted with the combustion gas. There is no
requirement, however, for a minimum combustion temperature because an adequate minimum
temperature must be maintained to meet the THC operational standard.
Temperatures within a sewage sludge incinerator are typically monitored by
thermocouples located at various points within the system. The thermocouples are always
enclosed in a thermowell to protect the small thermocouple wires and the critical thermocouple
"hot" junction from direct exposure to the combustion gases and entrained dust particles.
Thermocouples are usually located near the exit of the combustion chamber to provide a
representative temperature reading away from the flame zone, which can otherwise cause erratic
temperature readings as well as damage to the thermocouple. Thermowells may extend several
inches past the inner wall of the refractory into the gas stream or may extend only to the depth
of the refractory. Thermowells that extend past the refractory provide a more accurate measure
of the gas temperature and respond more quickly to temperature changes. This type, however,
also may be subject to dust and slag buildup, which can slow response to temperature changes.
Thermocouples may also be located upstream of the APCD to provide a warning or control
mechanism for high temperature excursions that could damage control equipment.
7-7
-------
Thermocouples are available in a variety of types, with each type constructed of specific
metals or alloys. The temperature ranges and reported accuracy vary by type. The environment
for which the thermocouple is suited also varies. Periodic replacement of thermocouples and
checking the physical integrity of the thermowell and any outer dust buildup is the best
maintenance procedure. Because it is not practical to perform a high temperature calibration of
the thermocouple, only periodic replacement ensures that a properly operating thermocouple is
in place.
7.5 OPERATING PARAMETERS FOR AIR POLLUTION CONTROL DEVICES
Subpart E requires that the operating parameters for the APCDs be consistent with the
values determined through a performance test. Conditions are placed on the operating
conditions of the APCD to ensure that the system is functioning properly and that there are no
excess pollutant emissions. Permits for sewage sludge incinerators will include continuous
monitoring requirements for selected parameters that indicate adequate performance of the
APCDs. Such requirements will be developed on a case-by-case basis, depending on the APCD
used and facility-specific issues. A list of performance indicator parameters for various APCD
technologies is presented in Appendix M, along with the common measuring devices for the
respective parameters.
The performance indicator .parameters include technology-specific parameters, as well as
universal parameters. Examples of APCD technology-specific parameters include pressure drop
and liquid flow for wet scrubbers, and secondary voltage and secondary current for wet
electrostatic precipitators (WESPs). Because the performance of all APCDs is influenced by gas
flow rate and gas temperature, these two parameters are considered to be universal APCD
parameters and are included in the performance for each APCD technology. Systems such as
wet scrubbers, fabric filters (baghouses), wet and dry electrostatic precipitators, and semidry and
dry scrubbing systems may be required on some sewage sludge incinerators to meet the emission
levels proposed in the standards. Fired afterburners may also be required on some multiple-
hearth furnaces to meet the THC operational standard of the regulation.
7-8
-------
Due to the potential variety of APCDs, the Part 503 regulation requires that values for
the operating parameters of the APCD be determined during a performance test, and to
establish these parameters as permit conditions. The performance test is conducted to establish
an acceptable control efficiency for metal emissions.
7.6 THREATENED OR ENDANGERED SPECIES
Subpart E prohibits the firing of sewage sludge in a sewage sludge incinerator if it would
adversely affect a threatened or endangered species listed under Section 4 of the Endangered
Species Act or its designated critical habitat. EPA will develop guidance to carry out this
provision consistent with the Endangered Species Act.
7-9
-------
SECTION EIGHT
FREQUENCY OF MONITORING, RECORDKEEPING, AND REPORTING
8.1 FREQUENCY OF MONITORING
The frequency of monitoring for arsenic, cadmium, chromium, lead, and nickel is set by
the regulation according to the amount of sewage sludge fired in a sewage sludge incinerator
during a 365-day period, and ranges from once per year to once per month (see Table 8-1). The
calculations used to develop the different amounts of sewage sludge on which the monitoring
frequency is based are shown in Appendix N. The calculations are based on treatment works
with flow rates of 1 million gallons per day (1 MGD, corresponding to 290 dry metric tons per
year for use or disposal), 5 MGD (corresponding to 1,500 dry metric tons per year), and 50
MGD (corresponding to 15,000 dry metric tons per year). The regulation also allows the
permitting authority to modify the frequency of monitoring for these five pollutants after the
sewage sludge is monitored for two years in accordance with the frequency set forth in Subpart
E, as long as the frequency of monitoring is at least once per year.
The frequency of monitoring for beryllium and mercury is to be specified by the
permitting authority. In addition, the regulation requires the continuous monitoring of the exit
gas for THC, oxygen concentration, and information used to determine moisture content, as well
as combustion temperature. The operating parameters for the sewage sludge incinerator
APCD(s) are to be monitored as specified by the permitting authority.
8.2 RECORDKEEPING
Any person who fires sewage sludge in a sewage sludge incinerator must retain certain
data for 5 years. This information is needed to show that the Part 503 requirements are being
met. The required data include the following:
8-1
-------
TABLE 8-1
FREQUENCY OF MONITORING—INCINERATION
Amount of Sewage Sludge*
(Metric Tons per 365-Day Period)
Greater than zero but less than 290
Equal to or greater than 290 but
less than 1,500
Equal to or greater than 1,500 but
less than 15,000
Equal to or greater than
15,000
Frequency
Once per year
Once per quarter
(four times per year)
Once per 60 days
(six times per year)
Once per month
(twelve times per year)
'Amount of sewage sludge fired in a sewage sludge incinerator—dry weight basis.
8-2
-------
Concentration of arsenic, cadmium, chromium, nickel, and lead in the sewage
sludge.
The concentration of THC in the exit gas.
Information that indicates the NESHAPs requirements for beryllium, if required,
and mercury are met.
The oxygen concentration and information used to measure moisture content in
the exit gas.
Sewage sludge feed rate for each sewage sludge incinerator unit, on a dry weight
basis.
The stack height for the sewage sludge incinerator.
The dispersion factor for the site where the sewage sludge incinerator is located.
The control efficiency for arsenic, cadmium, chromium, nickel, and lead for each
sewage sludge incinerator unit.
The risk-specific concentration for chromium calculated using the site-specific
equation for chromium presented in Section 5.4.2, if applicable.
A calibration and maintenance log for instruments used to measure the THC
concentration, oxygen concentration, combustion temperature, and information
needed to determine the moisture content in the exit gas from the sewage sludge
incinerator stack.
The combustion temperatures, including the maximum combustion temperature.
Values for the APCD operating parameters.
8J REPORTING
The reporting requirements under Subpart E pertain to Class I sewage sludge
management facilities and treatment works with a flow rate equal to or greater than one MGD
or that serve a population of 10,000 people or greater. All treatment works operating sewage
sludge incinerators are classified as Class I sewage sludge management facilities. Those
treatment works are required, therefore, to report yearly, except as specified in a permit issued
by the permitting authority.
8-3
-------
SECTION NINE
REFERENCES
Hughes, Wendy. 1991. Data Concerning Pass/Fail Facilities. Memorandum to Anne Jones,
Cambridge, MA: Abt Associates. May 14.
Cullen. 1987. Chronic Beryllium Disease in a Precious Metal Refinery. American Review of
Respiratory Diseases. Vol. 135. pp 201-208.
MITRE. 1983. The Estimation of Hazardous Waste Incineration Costs. U.S. EPA contract
no. 68-01-6092. McLean, VA: MITRE Corp. Pub. no. MTR-82W233.
MRI. 1990. Midwest Research Institute. Guidance Document for Testing and Permitting
Sewage Sludge Incinerators. Revised draft final report. Prepared for U.S. EPA.
NAS. 1983. National Academy of Sciences. Risk Assessment and Management: Framework
for Decision Making. Washington, D.C.
NIOSH. 1979. National Institute of Occupational Safety and Health. Registry of Toxics
Effects of Chemical Substances.
Steinsberger, S.C., W.G. DeWees, H.E. Bostian, I.E. Knoll, E.P. Grumpier, M.R. Midgett,
VJ. Zatka, and J.S. Warner. 1992. Development of Stationary Source Emission
Measurement Methods of Hexavalent Chromium and Nickel Speciation for Sewage Sludge
Incinerators. Prepared for U.S. EPA. Air and Waste Management Association 85th Annual
Meeting and Exhibition. Paper 92-46.03. Kansas City, Missouri.
U.S. EPA. 1982. Fate of Priority Pollutants in Publicly-Owned Treatment Works. Vol. I.
Effluent Guidelines Division. Washington, DC. EPA 440/1-82-303.
U.S. EPA. 1983a. The Record of Proceedings on the OWRS Municipal Sewage Sludge
Committee. Washington, DC.
U.S. EPA. 1983b. United States Environmental Protection Agency. Quality Assurance
Handbook for Air Pollution Measurement Systems: Volume IV. Meteorological
Measurements. EPA/600/4-82/060. Environmental Monitoring Systems Laboratory.
Research Triangle Park, North Carolina. February.
U.S. EPA. 1984. Mercury Health Effects Update, Health Issue Assessment. Office of Health
and Environmental Assessment, Environmental Criteria and Assessment Office. Research
Triangle Park, NC. EPA-600/8-84-019F.
U.S. EPA. 1985a. Environmental Profiles and Hazard Indices for Constituents of Municipal
Sludge: Arsenic. Office of Water Regulations and Standards. Washington, DC.
9-1
-------
U.S. EPA. 1985b. Environmental Profiles and Hazard Indices for Constituents of Municipal
Sludge: Beryllium. Office of Water Regulations and Standards. Washington, DC.
U.S. EPA. 1985c. Environmental Profiles and Hazard Indices for Constituents of Municipal
Sludge: Cadmium. Office of Water Regulations and Standards. Washington, DC.
U.S. EPA. 1985d. Environmental Profiles and Hazard Indices for Constituents of Municipal
Sludge: Chromium. Office of Water Regulations and Standards. Washington, DC.
U.S. EPA. 1985e. Environmental Profiles and Hazard Indices for Constituents of Municipal
Sludge: Lead. Office of Water Regulations and Standards. Washington, DC.
U.S. EPA. 1985f. Environmental Profiles and Hazard Indices for Constituents of Municipal
Sludge: Mercury. Office of Water Regulations and Standards. Washington, DC.
U.S. EPA. 1985g. Environmental Profiles and Hazard Indices for Constituents of Municipal
Sludge: Nickel. Office of Water Regulations and Standards. Washington, DC.
U.S. EPA. 1985h. Summary of Environmental Profiles and Hazard Indices for Constituents
of Municipal Sludge: Methods and Results. Office of Water Regulations and Standards.
Washington, DC.
U.S. EPA. 1985i. Guideline for Determination of Good Engineering Practice Stack Height
(Technical Support Document for the Stack Height Regulations). Revised. Office of Air
Quality Planning and Standards. Research Triangle Park, NC. EPA-450/4-80-023R.
U.S. EPA. 1986a. State Sludge Management Program Regulations. 51 Fed. Reg. 4458.
February 4.
U.S. EPA. 1986b. Guidelines for Carcinogen Assessment: Guidelines for Estimating
Exposure; Guidelines for Mutagenicity Risk Assessment; Guidelines for Health Assessment
of Suspect Developmental Toxicants; Guidelines for Health Risk Assessment of Chemical
Mixtures. Federal Register. Vol.51, no.185.
U.S. EPA. 1986c. Air Quality Criteria for Lead. Office of Health and Environmental
Assessment, Environmental Criteria and Assessment Office. Research Triangle Park, NC.
U.S. EPA. 1986d. Guideline on Air Quality Models (revised). Office of Air Quality,
Planning and Standards. Research Triangle Park, NC. EPA-450/2-78-027R, July.
U.S. EPA. 1987a. United States Environmental Protection Agency. On-Site Meteorological
Program Guidance for Regulatory Modeling, Applications. EPA/450/4-87/013. Office of Air
Quality Planning and Standards. Research Triangle Park, North Carolina.
U.S. EPA. 1987b. United States Environmental Protection Agency. Ambient Monitoring
Guidelines for Prevention of Significant Deterioration (PSD). EPA/450/4-87/007. Office of
Air Quality Planning and Standards. Research Triangle Park, North Carolina. May.
9-2
-------
U.S. EPA. 1988a. State Sludge Management Program Regulations. 53 Fed. Reg. 7642.
March 9.
U.S. EPA. 1988b. Development of Risk Assessment Methodology for Municipal Sludge
Incineration. Draft. Environmental Criteria and Assessment Office, Office of Health and
Environmental Assessment. Cincinnati, OH.
U.S. EPA. 1989. Report of the Municipal Sludge Incineration Subcommittee. Office of
Administrator, Science Advisory Board. Washington, DC. EPA-SAB-EEC-89-03520460,
September.
U.S. EPA. 1990a. Exposure Factors Handbook. Office of Health and Environmental
Assessment. Washington, DC. EPA/600/8-89/043.
U.S. EPA. 1990b. Supplement B to the Guideline on Air Quality Models (revised). Office
of Air and Radiation and Office of Air Quality Planning and Standards. Research Triangle
Park, NC. (Draft)
U.S. EPA. 1990c. Sludge Incineration Modeling (SIM) System User's Guide. Office of
Pesticides and Toxic Substances, Exposure Evaluation Division. Prepared for U.S. EPA.
(Draft)
U.S. EPA. 1991a. Emissions of Metals, Chromium and Nickel Species, and Organics from
Municipal Wastewater Sludge Incinerators. Volume III: Site 6 Emission Test Report. Risk
Reduction Engineering Laboratory, Office of Research and Development. Cincinnati, OH.
EPA 600/R-32/003c. PB92 151570/AS.
U.S. EPA. 1991b. Emissions of Metals, Chromium and Nickel Species, and Organics from
Municipal Wastewater Sludge Incinerators. Volume VI: Site 8 Emission Test Report. Risk
Reduction Engineering Laboratory, Office of Research and Development. Cincinnati, OH.
EPA 600/R-32/003f. PB92 151604/AS.
U.S. EPA. 1991c. Emissions of Metals, Chromium and Nickel Species, and Organics from
Municipal Wastewater Sludge Incinerators. Volume VIII: Site 9 Emission Test Report.
Risk Reduction Engineering Laboratory, Office of Research and Development. Cincinnati,
OH. EPA 600/R-32/003h. PB92 151620/AS.
U.S. EPA. 1991d. Ratio of Hexavalent to Total Chromium Incineration Emission.
Memorandum to Alan Rubin from Helen Jacobs. Office of Science and Technology,
Economic and Statistics Analysis Branch. Washington, DC. June 28.
U.S. EPA. 1991e. Methods Manual for Compliance with the BIF Regulation. Office of
Solid Waste, Washington, DC. EPA/530-SW-91-010.
U.S. EPA. 1991f. Emissions of Metals, Chromium and Nickel Species, and Organics from
Municipal .Wastewater Sludge Incinerators. Volume II: Site 1 Emission Test Report. Risk
Reduction Engineering Laboratory, Office of Research and Development. Cincinnati, OH.
EPA 600/2-91/007b. PB91 151498.
9-3
-------
U.S. EPA. 1991g. Emissions of Metals, Chromium and Nickel Species, and Organics from
Municipal Wastewater Sludge Incinerators. Volume III: Site 2 Emission Test Report. Risk
Reduction Engineering Laboratory, Office of Research and Development. Cincinnati, OH
EPA 600/2-91/007C. PB91 151506.
U.S. EPA. 1991h. Emissions of Metals, Chromium and Nickel Species, and Organics from
Municipal Wastewater Sludge Incinerators. Volume V: Site 3 Emission Test Report. Risk
Reduction Engineering Laboratory, Office of Research and Development. Cincinnati, OH.
EPA 600/2-91/007e. PB91 151-522.
U.S. EPA. 1991L Emissions of Metals, Chromium and Nickel Species, and Organics from
Municipal Wastewater Sludge Incinerators. Volume VI: Site 4 Emission Test Report. Risk
Reduction Engineering Laboratory, Office of Research and Development. Cincinnati, OH.
EPA 600/2-91/007f. PB91 151530.
U.S. EPA. 1991j. Emissions of Metals, Chromium and Nickel Species, and Organics from
Municipal Wastewater Sludge Incinerators. Volume : Site 10 Emission Test Report. Risk
Reduction Engineering Laboratory, Office of Research and Development. Cincinnati, OH.
U.S. EPA. 1991k. Background Information on the Risk of Organic Emissions from Sewage
Sludge Incinerators. Prepared by Midwest Research Institute for the EPA. MRI project no.
9102-L(36). Office of Water. Washington, DC.
U.S. EPA. 1992a. Integrated Risk Information System (IRIS). [Current file; updated as
necessary.] Washington, DC. Available through the National Library of Medicine.
U.S. EPA. 1992b. Laboratory and Field Evaluations of a Methodology for Determining
Hexavalent Chromium Emissions from Stationary Sources. Atmospheric Research and
Exposure Assessment Laboratory. Research Triangle Park, NC. EPA/600/S3-91/052.
U.S. EPA. 1992c. Emissions of Metals, Chromium and Nickel Species, and Organics from
Municipal Wastewater Sludge Incinerators. Risk Reduction Engineering Laboratory.
Cincinnati, OH. EPA/600/SR-92/003.
U.S. EPA. 1992d. User's Guide for the Industrial Source Complex (ISC2) Dispersion
Models - Volumes I, II, in. Office of Air Quality, Planning and Standards, Research
Triangle Park, NC.
U.S. EPA. 1992e. POTW Sludge Sampling and Analysis Guidance document. Second
Edition. Office of Wastewater Enforcement and Compliance. Washington, DC.
[Forthcoming]
U.S. 'EPA. 1992f. Statistical Support for the Proposed Regulatory Level on Total
Hydrocarbon Emissions from the Incineration of Sewage Sludge. Memorandum to Al Rubin
from George Zipf. Office of Science and Technology, Economic and Statistics Analysis
Branch. Washington, DC. November 10.
9-4
-------
U.S. EPA. 1992g. A Statistically Defensible Estimate of the Difference Between a Sample
of Total Hydrocarbon Emissions Measured with Unheated Sample Lines. Memorandum to
Al Rubin from George Zipf. Office of Science and Technology, Economic and Statistics
Analysis Branch. Washington, DC. U.S. EPA. November 10.
U.S. EPA. 1992h. Human Health Risk Assessment for the Use and Disposal of Sewage
Sludge: Benefits of Regulation. Office of Water. Washington, DC.
WPCF. 1988. Water Pollution Control Federation—Incineration—Manual of Practice No.
OM-11. Operations and Maintenance Series. Alexandria, VA: Water Pollution Control
Federation.
9-5
-------
APPENDIX A
STANDARDS FOR THE USE OR DISPOSAL OF SEWAGE SLUDGE
Subpart A—General Provisions
Subpait E—-Incineration
-------
Federal BagiaUr r VbL 58. Mb. 32 T Friday. Feoiuaey 19, 1093 / Rule* and Regulations 9347
UM of or fired in e sewage sludge
incinerator. Also included in this part
ara reporting requirements for Class I .
sludge management facilities, publicly
owned treatment works (POTWs) with 8
design flow rats-equal to or greater than
one million gallons per day. and POTWs
that serve 10.000 people or more.
(b) Applicability. (1) This part applies
to any person who prepares sewage
sludge, applies sewage sludge to the
land, or ares sewage sludge in a sewage
sludge incinerator end to the owner/
operator of a surmce disposal site.
(2) This part applies to sewage sludge
applied to the land, placed on a surface
disposal site, orfireo in a sewage sludge
incinerator.
(3) This part applies to the exit gas
from a sewage sludge incinerator stack.
A-l
-------
9388 Federal Register / Vol. 58. No. 32 / Friday. February 19. 1993 / Rules and Regulations
(4) This part applies to land where
sewage sludge is applied, to a surface -
disposal site, and to a sewage sludge
incinerator.
f 50&2 Compliance period.
(a) Compliance with the standards in
this part shall be achieved as
expeditiously as practicable, but in no
case later than February 19.1994. When
compliance with the standards requires
construction of new pollution control
facilities, compliance with the standards
shall be achieved u expeditiously as
practicable, but in no case later than
February 19.199S.
.. (b) The requirements for frequency of
monitoring, recordkeeping. and
reporting in this part for total
hydrocarbons in the exit gas from a
sewage sludge incinerator are effective
February 19,1994 or, if compliance
with the operational standard for total
hydrocarbons in this part requires the
construction of new pollution control
facilities, February 19.1995.
(c) All other requirements for
frequency of monitoring, recordkeeping.
and reporting in this part are effective
on July 20,1993.
S503J Permits end direct enta
ibiUty.
(a) Permits. The requirements in this
part may be implemented through a
permit:
(1) Issued to a "treatment works
treating domestic sewage", as defined in
40 CFR 122.2. in accordance with 40
CFR parts 122 and 124 by EPA or by a
State that has a State sludge
management program approved by EPA
in accordance with 40 CFR pert 123 or
40 CFR part 501 or
(2) Issued under subtitle C of the
Solid Waste Disposal Act: part C of the
Safe Drinking Water Act: the Marine
Protection. Research, and Sanctuaries
Act of 1972: or the Clean Air Act
"Treatment works treating domestic
sewage" shall submit e permit
application in accordance with either 40
CFR 122,21 or an approved State
program.
(b) Direct enforcaabfflty. No person
shall use or dispose of sewage sludge
through any practice far which
requirements are established in this part
except in accordance with such.
requirements.
§503.4 RetettoraMp to ottiar regulation*.
Disposal of sewage sludge in •
municipal solid waste landfill unit, as
defined in 40 CFR 258.2. that complies
with the requirements in 40 CFR part
258 constitutes compliance with section
405(d) of the CWA. Any person who
prepares sewage sludge that is disposed
in a municipal solid wast* landfill unit
shall ensure that the sewage sludge
meets the requirements in 40 CFR part
258 concerning the quality of materials
disposed in a municipal solid waste
landfill unit.
1503.5 AddWonalormoreartngant
requirement*.
(a) On a case-by-case basis, the
permitting authority may impose
requirements for the use or disposal of
sewage sludge in addition to or more
stringent than the requirements in this
part when necessary to protect public
health and the environment from any
adverse effect of a pollutant in the
sewage sludge.
(b) Nothing in this part precludes a
State or political subdivision thereof or
interstate agency from imposing
requirements for the use or disposal of
sewage sludge more stringent than the
requirements in this part or from
imposing additional requirements for
the use or disposal of sewage sludge.
i 503.1 Eicluelona.
(a) Treatment processes. This pert
does not establish requirements for
processes used to treat domestic sewage
or for processes used to treat sewage
sludge prior to final us* or disposal.
except as provided in $ 503.32 and
§503.33.
(b) Selection of a use or disposal
practice. This part-does not require the
selection of a sewage sludge use or
disposal practice. The determination of
the manner in which sewage sludge is
used or disposed is a local
determination.
(c) Co-firing of sewage sludge. This
part does not establish requirements for
sewage sludge co-fired in an incinerator
with other wastes or for the incinerator
in which sewage sludge end other
wastes are co-fired. Other wastes do not
include auxiliary fuel, as defined in 40
CFR 503.41 (b), fired in • sewage sludge
incinerator.
(d) Sludge generated at an industrial
facility. This part does not establish
requirements for the us* or disposal of
sludge generated at an industrial facility
during the treatment of industrial
wastewater. including sewage sludg*
generated during the treatment of
industrial wastewater combined with
domestic sewage.
(e) Hazardous sewage sludge. This
pert does not establish requirements for
the use or disposal of sewage sludg*
determined to be hazardous in
accordance with 40 CFR part 261.
(f) Sewage sludge with high KB
concentration. This part does not
establish requirements for the use or
disposal of sewage sludge with e
concentration of polychlorinated
biphenyls (PCBs) equal to or greater
than 50 milligrams per kilogram of total
solids (dry weight basis).
(g) Incinerator ash. This part does not
establish requirements for the use or
disposal of ash generated during the
firing of sewage sludge in a sewage
sludge incinerator.
(h) Grit and screenings. This part does
not establish requirements for the use or
disposal of grit (e.g., sand, gravel.
cinders, or other materials with a high
specific gravity) or screenings (e.g..
relatively large materials such as rags)
generated during preliminary treatment
of domestic sewage in a treatment
works.
(i) Drinking water treatment sludge.
This part does not establish
requirements for the use or disposal of
sludge generated during the treatment of
either surface water or ground water
used for drinking water.
(j) Commercial and industrial septage.
This part does not establish
requirements for the use or disposal of
commercial septage, industrial septage.
a mixture of domestic septage and
commercial septage, or a mixture of
domestic septage and industrial'septage.
1503.7 Requirement f or e person who .
prepare* eewege sludge.
Any person who prepares sewage
sludge shall ensure that the applicable
requirements in this part are met when
the sewage sludge is applied to the land.
placed on a surface disposal site, or
fired in a sewage sludge incinerator.
15034 Sampling end analyst*.
(a) Sampling. Representative samples
of sewage sludge that is applied to the
land, placed on a surface disposal sit*.
or fired in a sewage sludg* incinerator
shall be collected and analyzed.
(b) Methods. The materials listed
below are incorporated by reference in
this part. These incorporations by
reference were approved by the Director
of the Federal Register in accordance
with 5 U.S.C. 552(a) and 1 CFR part 51.
The materials are incorporated as they
exist on the data of approval, and notice
of any change in these materials will b*
published in the Federal Register. They
are available for inspection at the Office
of the Federal Register. 7th Floor, suit*
700.800 North Capitol Street NW..
Washington. DC and at the Office of
Water Docket, room L-102, U.S.
Environmental Protection Agency. 401
M Street SYV.. Washington. DC Copies
may be obtained from the standard
producer or publisher listed in the
regulation. Methods in the materials
listed below shall be used to analyze
samples of sewage sludge.
A-2
-------
Federal Register / Vok 58. No. 32 / Friday, February 19. 1993 / Rule* and Ragubtions 93*4
(1) Enteric viruses. ASTM
Designation: D 4994-89. "Standard
Practice for Recovery of Viruses From.
Wastewater Sludgee". 1992 Annual
Book of ASTM Standards; Section 11—
Water and Environmental Technology,
ASTM. 1916 Race Street Philadelphia.
PA 19103-1137.
(2) Fecal coliform. Part 9221E or Part
9222 D.. "Standard Methods for the-.
Examination of Water and Wastewater",
18th Edition. 1992. American Public
Health Association. 1015 15th Street
NW.. Washington. DC 20003.
(3) Helminth ova. Yanko, W.A..
"Occurrence of Pathogens in
Distribution and Marketing Municipal
Sludges". EPA 600/1-67-014.1987.
National Technical Information Service.
5285 Port Royal Road. Springfield.
Virginia 22161 (PB 88-154273/AS).
(4) Inorganic pollutant* 'Test
Methods for Evaluating Solid Waste.
Physical/Chemical Methods". EPA
Publication SW-846. Second Edition
(1982) with Updates I (April 1984) and
II (April 1985) and Third Edition
(November 1986) with Revision I
(December 1987). Second Edition and
Updates I and II are available from the
National Technical Information Service.
5285 Port Royal Road. Springfield.
Virginia 22161 (PB-87-120-291). Third
Edition and Revision I are available
from Superintendent of Documents.
Government Printing Office, 941 North
Capitol Street. NE., Washington, DC
20002 (Document Number 933-001-
00000-1).
(5) Salmonella sp. bacteria. Part 9260
D.. "Standard Methods for the
Examination of Water and Wastewater",
18th Edition. 1992. American Public
Health Association. 1015 15th Street
NW., Washington. DC 20003; or
Kenner. B.A. and H.P. Clark,
"Detection and enumeration of
Salmonella and Pseudomonas
aeruginosa". Journal of the Water
Pollution Control Federation. VoL 46,
no. 9, September 1974. pp. 2163-2171.
Water Environment Federation. 601
Wythe Street. Alexandria. Virginia
22314.
(6) Specific oxygen uptake rota. Part
2710 B.. "Standard Methods for the
Examination of Water and Wastewater".
18th Edition, 1992. American Public
Health Association, 101515th Street
NW.. Washington. DC 20003.
(7) Total, fixed, and volatile so/ids.
Part 2540 C.. "Standard Methods for the
Examination of Water and Wastewater",
18th Edition. 1992. American Public .
Health Association. 1015 15th Street
NW.. Washington. DC 20005.
f SOU General osflnttene.
(a) Apply sewage sludge or sewage
sludge applied to the land means land
application of sewage sludge. ,
lb) Base flood is a flood that has a. on*
percent chance of occurring in any
given year (i.e.. a flood with a
magnitude equalled one* ia 100 years).
(c) Class 1 sludge management facility
is any publicly owned treatment works
(POTW), as denned in 40 CFR 501.2,
required to have an approved
pretreatment program under 40 CFR
403.8(a) (including any POTW located
in a State that has elected to assume
local piugism responsibilities pursuant
to 40 CFR 403.10(a)J and any treatment
works treating domestic sewage, as
defined in 40 CFR 122.2. classified as a
Class I sludge management fuility by
the EPA Regional Administrator, or. ia
.the case of approved State programs, to*
Regional Administrator ia i
with the State Director, because of the)
potential for its sewage sludge use or
i disposal practice to afreet public health
and the environment adversely.
(d) Cover crop is a small grain crap,
such as oats, wbeat. or barley, not grown
for harvest
(a) CWA means the Clean Water Act
(formerly referred to as either the
Federal Water Pollution Act or the
Federal Water Pollution Control Act
Amendments of 1972), Public Law 92-
500. as amended by Public Law 93-217,
Public Law 95-578, Public Law 96-483,
Public Law 97-117, and Public Law
100-4.
(f) Domestic septage is either liquid or.
solid material removed from a septic
tank, cesspool, portable toilet Type ffl
marine sanitation device, or similar'
treatment works that receives only
domestic sewage. Domestic septage does
not include liquid or solid material
removed from a septic tank, cesspool, or
similar treatment works that receive*
either commercial wastewater or
industrial wastewater and does not
include grease removed from a greas*
trap at a restaurant
(g) Domestic sewage is waste and
wastewater from imm«i« or household
operations that is* discharged to or
otherwise enters a treatment works.
(h) Dry weight basis means calculated
on the basis of having been dried at 103
degrees Celsius until reaching a
constant mass (i-a.. essentially 160
D6TC8De> (OUflel CQOt^ffltl»
(i) EPA means the United States
Environmental Protection Agency.
(j) Feed crops are crops produced
primarily for consumption by •«»™«if-
(k) Fiber crops are crops such as flax
and cotton.
(1) food crops ve crops consumed by
humans. Those mclude. but are not
limited to. fruits, vegetables, and
tobacco.
(m) Ground water is water below the
land surface in the saturated zone.
(n) Industrial wastewater is
wastewater generated in a commercial
or industrial process.
(o) Municipality means a city. tcr,~.
borough, county, parish, district.
association, or other public body
(including an intermunicipal Agency of
two or more of the foregoing entities)
created by or under State law; an Indian
tribe or an authorized Indian tribal
organization having jurisdiction over
sewage sludge management; or a
designated and approved management
Agency under section 208 of the CWA.
as amended. The definition includes a
special district created under State law,
such as a water district sewer district.
sanitary district utility district drainage
district or similar entity, or ac
integrated waste management facility as
defined in section 201(e) of the CWA. as
amended, that has as one of its principal
responsibilities the treatment transport.
use. or disposal of sewage sludge.
(p) Permitting authority is either EPA
or a State with an EPA-approved sludge
tprogram.
(q) Person is an individual.
association, partnership, corporation.
municipality, State or Federal agency, or
an agent or employee thereof.
(r) Person who prepares sewage
sludge is either the person who
generates sewage sludge during the
treatment of domestic sewage in •
treatment works or the person who
derives a material from sewage sludge.
(s) Place sewage sludge or sewage
sludge placed means disposal of sewage
sludge on a surface disposal site.
(t) Polrutant is an organic substance,
an inorganic substance, a combination
of organic and inorganic substances, or
a pathogenic organism that after
discharge end upon exposure, ingesttan.
inhalation, or assimilation into an *
organism either directly from th*
environment or indirectly by Ingestion
through the food chain, could, on the
basis of information available to the
Administrator of EPA, cause death..
disease, behavioral abnormalities, ' .
cancer, genetic mutations, physiological
malfunctions (Including malfunction in
reproduction), or physical deformations
in either organisms or offspring of the
organisms.
\u) Pollutant limit is s numerical
value that describes the amount of a
pollutant allowed per unit amount of
sewage sludge (e.g.. milligrams per
kilogram of total solids); the amount of
a pollutant that can be applied to a unit
area, of land (eg- kilograms per hectare);
or the volume of a material that can be
A-3
-------
939O Federal Register / Vol. 58. No. 32 / Friday. February 19. 1993 / Rules and Regulations
applied to a unit ana of land (e.g., .
gallons per acre).
(v) Runoff is rainwater, leechate. or
other liquid that drains overland on any
part of a land surface and runs off of the
land surface.
(w) Sewage sludge is solid, semi-solid.
or liquid residue generated during the
treatment of domestic sewage in a
treatment works. Sewage sludge
includes, but is not limited to, domestic
septage: scum or solids removed in
primary, secondary, or advanced
wastewater treatment processes; and a
material derived from sewage sludge.
Sewage sludge does not include ash
generated during the firing of sewage
sludge in a sewage sludge incinerator or
grit and screenings generated during
preliminary treatment of domestic
sewage in a treatment works.
(x) State is one of the United States of
America, the District of Columbia, the
Commonwealth of Puerto Rico, the
Virgin Islands, Guam, American Samoa.
the Trust Territory of the Pacific Islands.
the Commonwealth of the Northern
Mariana Islands, and an Indian Tribe
eligible for treatment as a State pursuant
to regulations promulgated under the
authority of section 518(e) of the CWA.
(y) Store or storage of sewage sludge
is the placement of sewage sludge on
land on which the sewage sludge
remains for two years or less. This does
not include the placement of sewage
sludge on land for treatment
(z) Treat or treatment of sewage
sludge is the preparation of sewage
sludge for final use or disposal. This
includes, but is not limited to.
thickening, stabilization, and
dewatering of sewage sludge. This does
not include storage of sewage sludge.
(aa) Treatment works is either a
federally owned, publicly owned, or
privately owned device or system used
to treat (including recycle and reclaim)
either domestic sewage or a
combination of domestic sewage and
industrial waste of a liquid nature.
(bb) Wetlands means those areas that
are inundated or saturated by surface)
water or ground water at • frequency
and duration to support, and that under
normal circumstance* do support, a
prevalence of vegetation typically
adapted for life in saturated soil
conditions. Wetlands generally include
swamps, marshes, bogs, and similar
areas.
Subpavt B-Und Application
f 503.10 Applicability.
(a) This subpart applies to any person
who prepares sewage sludge that is
applied to the land, to any person who
applies sewage sludge to the land, to
sewage sludge applied to the land, and
to the land on which sewage sludge is
applied.
(b)(l) Bulk sewage sludge. The general
requirements in § 503.12 and the
management practices in 5 503.14 do
not apply when bulk sewage sludge is
applied to the land if the bulk sewage
sludge meets the pollutant
concentrations in § 503.13(b){3). the
Class A pathogen requirements in
$ 503.32(a). and one of the vector
attraction reduction requirements in
$ 503.33 (bHD through (b)(8).
(2) The Regional Administrator of
EPA or. in the case of a State with an
approved sludge management program.
the State Director, may apply any or all
of the general requirements in § 503.12
and the management practices in
§ 503.14 to the bulk sewage sludge in
§ 503.10(b)(l) on a case-by-case basis
after determining that the general
requirements or management practices
are needed to protect public health and
the environment from any reasonably
anticipated adverse effect that may
occur from any pollutant in the bulk
sewage sludge.
(c)fl) The general requirements in
$ 503.12 and the management practices
in $ 503.14 do not apply when a bulk
material derived from sewage sludge is
applied to the land if the derived bulk
material meets the pollutant
concentrations in $ 503.13(b)(3). the
Class A pathogen requirements in
§ 503.32(a). and one of the vector
attraction reduction requirements in
§503.33 (b)(l) through (b)(8).
(2) The Regional Administrator of
EPA or, in the case of a State with an
approved sludge management program.
the State Director, may apply any or all
of the general requirements in $ 503.12
or the management practices in § 503.14
to the bulk material in $ 503.10(c)(l) on
a case-by-case basis after determining
that the general requirements or
management practices are needed to
protect public health and the
environment from any reasonably
anticipated adverse effect that may
occur from any pollutant in the bulk
sewage sludge.
(d) The requirements in this subpart
do not apply when a bulk material
derived from sewage sludge is applied
to the land if the sewage sludge from
which the bulk material is derived
meets the pollutant concentrations in
S 503.13(b)(3). the Class A pathogen
requirements in § S03.32(a). and one of .
the vector attraction reduction
requirements in § 503.33 (b)(l) through'
(e) Sewage sludge sold or given away
in a bag or other container for . • .
application to the land. The general
requirements in S 503.12 and the
management practices in $ 503.14 do
not apply when sewage sludge is sold or
given away in a bag or other container
for application to the land if the sewage
sludge sold or given away in a bag or
other container for application to the
land meets the pollutant concentrations
in $ 503.13(b)(3). the Class A pathogen
requirements in $ 503.32(a). and one of
the vector attraction reduction
requirements in $ 503.33 (b)(l) through
(0 The general requirements in
$ 503.12 and the management practices
in § 503.14 do not apply when a
material derived from sewage sludge is
sold or given away in a bag or other
container for application to the land if
the derived material meets the pollutant
concentrations in $ 503.13(b)(3). the
Class A pathogen requirements in
$ 503.32U). and one of the vector
attraction reduction requirements in
S 503.33 (b)(l) through fb)(8).
(g) The requirements in this subpart
do not apply when a material derived
from sewage sludge is sold or given
away in a bag or other container for
application to the land if the sewage
sludge from which the material is
derived meets the pollutant
concentrations in § 503.13(b){3), the
Class A pathogen requirements in
5 503.32(a). and one of the vector
attraction reduction requirements in
$ 503.33 (b)(l) through (b}(8).
1503.11 SpedetdeflnMone.
(a) Agricultural land is land on which
a food crop, a feed crop, or a fiber crop
is grown. This includes range land and
land used as pasture.
(b) Agronomic rate is the whole
sludge application rate (dry weight
basis) designed:
(1) To provide the amount of nitrogen
needed by the food crop, feed crop, fiber
crop, cover crop, or vegetation grown on
the land; and
(2) To minimize the amount of
nitrogen in the sewage sludge that
passes below the root zone of the crop
or vegetation grown on the land to the
ground water.
(c) Annual pollutant loading rate is
the maximum amount of a pollutant that
can be applied to a unit ana of land
during a 365 day period.
(d) Annual whole sludge application
rate is the T^jdimig* amount of sewage
sludge (dry weight basis) that can be
applied to a unit area of land during a
369 day period.
(e) Bulk sewage sludge is sewage
sludge that is not sold or given away in
a bag or other container for application
to the land.
A4
-------
Federal Refiner / Vol. 58, No. 32 / Friday. February 19. 1983 / Rules and Regulations 9401
septage) is placed on an active sewage
sludge unit
(S) One of the vector attraction
reduction requirement* in S 503.33
(b)(9). fb)(10). or (b)(12) shall be met
when domestic septage is applied to
agricultural land, rarest, or a
reclamation site and one of the vector
attraction reduction requirements in
$ 503.33 (b)(9) through (b)(12) shall be
met when domestic septage is placed on
an active sewage sludge unit
(b)(l) The mass of volatile solids in
the sewage sludge shall be reduced by
a minimum of 38 percent (see
calculation procedures in
"Environmental Regulations and
Technology—Control of Pathogens and
Vector Attraction in Sewage Sludge".
EPA-825/R-92/013.1992. U.S.
Environmental Protection Agency,
Cincinnati. Ohio 45268).
(2) When the 38 percent volatile
solids reduction requirement in
S 503.33(b)(l) cannot be met for an
anaerobically digested sewage sludge,
vector attraction reduction can be
demonstrated by digesting a portion of
the previously digested sewage sludge
anaerobically in the laboratory in a *
bench-scale unit for 40 additional days
at a temperature between 30 and 37
degrees Celsius. When at the end of the
40 days, the volatile solids in the
sewage sludge at the beginning of that
period is reduced by leas than 17
percent, vector attraction reduction is
achieved.
(3) When the 38 percent volatile -
solids reduction requirement in
§ 503.33(bXD cannot be met for an
aerobically digested sewage sludge.
vector attraction reduction can be
demonstrated by digesting a portion of
the previously digested sewage sludge .
that has a percent solids of two percent
or less aerobically in the laboratory in
a bench-scale unit for 30 additional days
at 20 degrees Celsius. When at the end
of the 30 days, the volatile solids in the
sewage sludge at the beginning of that
period is reduced by law than IS
percent, vector attraction reduction is
achieved.
(4) The specific oxygen uptake rate
(SOUR) for sewage sludge treated in an
aerobic process shall be equal to or less
than l.S milligrams of oxygen per hour
per gram of total solids (cay weight
basis) at a temperature of 20 degrees
Celsius.
(S) Sewage sludge shall be treated in
an aerobic process for 14 days or longer.
During that time, the temperature of the
sewage sludge shall be higher than 40
degrees Celsius and the average
temperature of the sewage sludge shall
be higher than 45 degrees Celsius.
(6) The pH of sewage sludge shall be
raised to 12 or higher by alkali addition
and. without the addition of more alkali.
shall remain at 12 or higher for two
hours and then at 11.3 or higher for an
additional 22 hours.
(7) The percent solids of sewage
sludge that does not contain
unstabilized solids generated in a
primary waatewatar treatment process
shall be equal to or greater than 75
percent based on the moisture content
and total solids prior to mixing with
other materials.
(8) The percent solids of i
sludge that contains unst '
generated in a primary wastewatar
treatment process shall be equal to or
greater than 90 percent based on the
moisture content and total solids prior
to mixing with other materials.
(9)(i) Sewage sludge shall be injected
below the surface of the land.
(ii) No significant amount of the
sewage sludge shall be present on the
land surface within one hour after the
sewage sludge is infected.
(Hi) When the sewage sludge that is
injected below the surface of the land is
Class A with respect to pathogens, the
sewage sludge shall be infected below
the land surface within eight hours after
being discharged from the pathogen
treatment process.
(10)(i) Sewage sludge applied to the
land surface or placed on a surface
disposal site shall be incorporated into
the soil within six hours after
application to or placement on the land.
Ui) When sewage sludge that is
incorporated into the sou is Class A
with respect to pathogens, the sewage
sludge shall be applied to or placed on
the land within eight hours after being
discharged from the pathogen treatment
process.
(11) Sewage sludge placed on an
active sewage sludge unit shall be
covered with soil or other material at
the end of each operating day.
(12) The pH of domestic septage shall
be raised to 12 or higher by alkali
addition and, without the addition of
more alkali, shall remain at 12 or higher
for 30 minutes.
tlon
Subawte-fctcta
(a) This subpart applies to a person
who fires sewage sludge in a sewage
sludge incinerator, to a sewage sludge
incinerator, and to sewage sludge fired
in a sewage sludge incinerator.
(b) This subpart applies to the exit gas
from a sewage sludge incinerator stack.
$503.41 Special deflnMone. '
(a) Air pollution control device is one
or more processes used to treat the exit
gas from a sewage sludge Incinerator
stack.
(b) Auxiliary fuel is fuel used to
augment the fuel value of sswage
sludge. This includes, but is not limited
to, natural gas, fuel oil, coal, gas
generated during anaerobic digestion of
sewage sludge, and municipal solid
waste (not to exceed 30 percent of the
dry weight of sewage sludge and
auxiliary fuel together). Hazardous
wastes are not auxiliary fuel
(c) Control efficiency is the mass of e
pollutant in the sewage sludge fed to an
incinerator minus the mass of that
pollutant in the exit gas from the
incinerator stack divided by the mass of
the pollutant in the sewage sludge fad
to theindi
(d) Dispersion factor is the ratio of the
increase in the ground level ambient air
concentration for a pollutant at or
beyond the property line of the site
where the sewage sludge incinerator is
located to the mass emission rate for the
pollutant from the incinerator stack.
(e) Fluidixed bed incinerator is an
enclosed device in which organic matter
and inorganic matter hi sewage sludge
are combusted in a bed of particles
suspended in the combustion chamber
gas.
(0 Hourfy overage is the arithmetic
mean of all measurements, taken during
an hour. At least two measurements Jj
must be taken during the hour. ™
(g) Incineration is the combustion of
organic matter and inorganic matter in
sewage sludge by high temperatures in
an enclosed device.
(h) Monthly overage is the arithmetic
mean of the hourly averages for the
hours a sewage sludge incinerator
operates during the month.
(i) Risk specific concentration is the
allowable increase in the average daily
ground level ambient air concentration
for a pollutant from the incineration of
sewage sludge at or beyond the property
line of the site where the sewage sludge
incinerator is located.
(j) Sewqge sludge feed rate is either
the average daily amount of sewage
sludge fired in all sewage sludge
incinerators within the property line of
the site where the sewage sludge
incinerators are located for the number
of days in a 365 day period that each
sewage sludge incinerator operates, or
the average daily design capacity for all
sewage sludge incinerators within the
property line of the site where the
sewage sludge incinerators an located.
00 Sewage sludge incinerator is an
enclosed device in which only sewage
sludge and auxiliary fuel an fired.
(I) Stock height is the difference
between the elevation of the top of a
sewage sludge incinerator stack «nd the
A-5
-------
9402 Federal Register / Vol. 58. No. 32 / Friday. February 19. 1993 / Rules and
elevation of the ground at the base of the
stack when the difference is equal to or
less than 65 meters. When the difference
is greater than 65 meters, stack height is
the creditable stack height determined
in accordance with 40 CPU SHOO (il).
(m) Total hydrocarbon* means the
organic compounds in the exit gas from
a sewage sludge incinerator stack
measured using a flame ionization
detection instrument referenced to
propane.
(n) Wet electrottatic pneipitator is an
air pollution control device that uses
both electrical forces and water to
remove pollutants in the exit gas from
a sewage sludge incinerator stack.
(o) Wet scrubber ia an air pollution
control device that uses water to remove
pollutants in the exit gas from a sewage
sludge incinerator stack.
4503.42 General requirements.
No person shall fire sewage sludge in
a sewage sludge incinerator except in
compliance with the requirements in
this subpart
(a) Firing of sewage sludge in a
sewage sludge incinerator shall not
violate the requirements in the National
Emission Standard for Beryllium in
subpart C of 40 CFR part SI.
(b) Firing of sewage sludge in a
sewage sludge incinerator shall not
violate the requirements in the National
Emission Standard for Mercury in
subpart E of 40 CFR part 61.
(cl Pollutant limit—lead.
(1) The daily concentration of lead in
sewage sludge fed to s sewage sludge
incinerator shall not exceed the
concentration calculated using Equation
(4).
0.1xNAAQSx5e.4OO
DPx<1 -CBJxSP
Eq.(4).
Miry
am of
Where:
ODaily concentration of lead ia
sludge in milligrams per k
total solids (dry weigbtba
NAAQS-National AmMee* Air Quality
Standard for lead ta •' *••"•/••"• par
cubic meter.
DF-OUpenUn (actor ta i
CC»Sewege sludge iadaantar control
efficiency for lead ia hundredth*.
SF-Sewage sludge bad rale ia metric toas
per day (dry weight basis).
(2)(i) When the sewage sludge stack
height is 65 meters or less, the actual
sewage sludge *i"*'M>'ttef stack ^•'gM
shall be used in an air dispersion model
specified by the permitting authority to
determine the dispersion factor (DP) in
equation (4).
(ii) When the sewage sludge
incinerator stack height exceeds 65
meters, the creditable stack height shall
be determined in accordance with 40
CFR Sl.lOO(ii) and the creditable stack
height shall be used in an air dispersion
modal specified by the permitting
authority to determine the dispersion
factor (DF) in aquation (4).
(3) The control efficiency (CE) la
equation (S) shall be determined from a.
performance test of the sewage sludge
incinerator, as specified by the
permitting authority.
(d) Pollutant limit—arsenic.
cadmium* chromium, and nickel.
(1) The daily concentration for
arsenic, cadmium, chromium, and
nickel in sewage sludge fed to a sewage
sludge incinerator each shall not exceed
the concentration calculated using
equation (S).
RSCxM.400
DFxDaily concentration of arsenic,
cadmium* rhtnmtnti^ of nickel ia
sewage sludge ia milligrams per
kilogram of total solids (dry weight
basis).
CEaSewage sludge Incinerator control
efficiency for arsenic cadmium.
chromium, or nickel in hundndths.
DfvOispenion factor ia tnicrograms per
cubic meter per gram per second.
RSC*Rlsk specific concentration la
micrograms per cubic meter. S
P»Sewage sludge feed rate ia metric tons
per day (dry weight basis).
(2) The risk specific concentrations
for arsenic, cadmium, and nickel used
in equation (6) shall be obtained from
Tablet of $503 .43.
2 o» §503.43.—RISK SPECIFIC
CONCENTRATX3H—CHROMIUM
Fumed bed *•»«* eaubber.
FluMtted bed wnn «et tcnjbMr
and wet eteovoetaSs preop^
tetor _.
Otter types wti wet acruceer ....
Other type* wan •* icruaber
and wet ettcmeiaac pteopt.
tftlQf ...............„.._..
RUfci
« _ .
(ittcregrama per
o.aa
073
0.094
0.014
RSG.
Where:
RSCrttk specific
Eq. (61
entration Cor
TABU 1 of $503.43.— ftsx Srt&nc
CONCENTRATION
ANONJCXfL
chromium in micrognms per cubic
meter used in aquation (5).
r»decimal fraction of the hexavalent
chromium concentration in the total
chromium concentration measured in
the exit gas from the sewage sludge
incinerator stack ia hundredths.
(4)(i) When the sewage sludge
incinerator stack height is equal to or
less than 65 meters, the actual sewage
sludge incinerator stack height shall be
used in an air dispersion model, aa
specified by the permitting authority, to
determine the dispersion factor (DF) in
equation (S).
(ii) When the sewage sludge
incinerator stack height is greater than
65 meters, the creditable stack height
shall be determined in accordance with
40 CFR SMOO(ii) and the creditable
stack height shall be used in an air
dispersion model, as specified by the
permitting authority, to determine the
dispersion factor (DF) in equation (S).
(S) The control efficiency (CE) in
equation (S) shall be determined from a
performance test of the sewage sludge
incinerator, as specified by the
permitting authority.
CtpmM. I *o*-*4
Potman
Anerte
Rtt
0.023
O.OS7
2JU
(a) The total hydrocarbons
concentration in the exit gas from s
sewage sludge incinerator shall be
corrected for zero percent moisture by
multiplying the measured total
hydrocarbons concentration by the
correction factor calculated using
equation (7).
(3) The risk specific concentration for
chromium used in equation (5) shall be
obtained from Table 2 of S 503.43 or
shall be calculated using equation (6). as
specified by the permitting authority.
Correctk
cent moisture)*
(t-X)
Eq. (7)
Where:
X«decunal fraction of the percent moisture
ia the sewage sludge incinerator exit gaa
ia huaflradxhs.
A-6
-------
Federal Register / Vol. 58, No. 32 / Friday. February 19. 1993 / Rules and Regulations 9403
(b) The total hydrocarbons
concentration in the exit gas (not a
saw«ge sludge incinerator shall be
corrected to seven percent oxygen by
multiplying the meanired total
hydrocarbons concentration by the
correction factor calculated using
equation (8).
Correction factor (ox-
14
(21—Y)
Eq.18)
Where:
Y»P«rcent oxygen concentration in the
sewage sludge incinentor stack exit gat
(dry volume/dry volume).
(c) The monthly average
concentration for total hydrocarfaona in
the exit gas from a sewage sludge
incinerator stack, corrected for zero
percent moisture using the correction
factor from equation (7) and to seven
percent oxygen using the correction
factor from equation (8). shall not
exceed 100 parts per million on a
volumetric basis when measured using
the instrument required by § 303.43(a).
§.503.43
(a)(l) An instrument that measures
and records the total hydrocarbons
concentration in the sewage sludge
incinerator stack exit gu continuously
shall be installed, calibrated, operated.
and maintained for each sewage sludge
incinerator, as specified by the
permitting authority.
(2) The total hydrocarbons instrument
shall employ a flame ionization
detector shall have a heated sampling
line maintained at a temperature of ISO
degrees Celsius or higher at all times;
and shall be calibrated at least once
every 24-hour operating period using
propane.
(b) An instrument that measures **"^
records the oxygen concentration in the
sewage sludge incinentor stack exit gee
continuously shall be installed,
calibrated, operated, and maintained far
each sewage sludge incinerator, ae
specified by the permitting authority.
(c) An instrument the* measures end
records information need to determine)
the moisture <,uiileiit in tne sewage
sludge incinerator stack exit gee
continuously shell be installed.
calibrated, operated, and »«•<««»•<««•«» for
eachsewaee L;-.; doe incinerator, as
specified b - -^Training authority.
(d) An ir - ant that measures and
records cor .-* in temperatures
continues :;i be t««»«iu«l
calibrate*: : ;ad. and maintained for
each sewn. ..-age incinerator, as
specified oy ihe permitting authority.
(e> The maximum combustion
temperature for a sewage, sludge
incinerator shall be specified by tbe«
permitting authority and shall be based
on information obtained during the
performance test of the sewage sludge
incinerator to determine pollutant
control efficiencies.
(0 The values for the operating
parameters for the sewage sludge
incinerator air pollution control device
shall.be specified by the permitting
authority and shell be based on
information obtained during the
performance test of the sewage sludge
incinerator to determine pollutant
control efficiencies.
(gf Sewage sludge shell not be fired in
a sewage sludge incinerator if it is likely
to adversely affect e threatened or
endangered spedee listed under section
4 of the Endangered Spede* Act or its
designated critical habitat.
|503.4« Frequency etmonfterlne.
(a) Sewage s/udge.
(1 ) The frequency of monitoring far
beryllium ana mercury shell be
specified by the permitting authority.
(2) The frequency of monitoring for
arsenic, r*^1"*""*! chromium* lead. •«"!
nickel in sewage sludge fed to a sewage
sludge incinerator shell be the
frequency in Table t of 8 303.46.
TA8l£ 1 OF §503.46.— FREQUENCY Of
MONTTORtNO— 4MONEJUTIOM
Amour* of sewae
ion* pel 368 day period)
Greater Man mo but las
290.
Equal to or greater ton 290 but
leaa man 1,500.
Equal to or greater tien i.SOO but
*•» man i&OOO.
Equal to or greater tian T&OOO —
Fiaquancy
Creeper year.
Onotperquar*
tar (tour
Bmeaper
Once per 60
ernes par
Ones per
more* 02
•mas per
(3) After the sewage sludge has been
monitored for two years at the frequency
in Table 1 of § 303.46. the permitting
authority may reduce the frequency of
monitoring for arsenic, cadmium.
chromium, lead, and nickel, but in no
case shall the frequency of monitoring
be less than once per year when sewegs
sludge is fired in e aewege sludge
incinentor.
(b) Total hydrocarbons, oxygen
concentration, information to determine
moisture content, and combustion
temperatures.
Tne total hydrocarbons concentration
and oxygeo concentration in the exit gee
from a sewage sludge incinerator stack.
the information used to measure ^
moisture content in the exit gas. and thej
combustion temperatures for the sewage
sludge incinentor shall be monitored
continuously.
(c) Air pollution control device
operating parameters.
The frequency of monitoring far the
sewage sludge incinerator air pollution
control device operating parameters
shall be specified by the permitting
authority.
(Approved by the Office of Management ud
Budget under control number 2040-0157)
IS03L47
(a) The person who fires sewage
sludge in e sewage sludge incinentor
shall develop *^*^ *"fr"*natiim in
S 503.47(b) through $303.47(n) and
shall retain that information for five
yean.
(b) The concentration of lead, arsenic,
cadmium, chromium, and nickel in the
sewage sludge fed to the sewage sludge .
incinerator.
(c) The total hydrocarbons
concentrations in the exit gas. from the
sewege sludge incinerator stack.
(d) Information that indicates thai
requirements in 0*^ National Emission
Standard for beryllium in subpert C of
40 CFR part 61 era met
(e) Information that indicates the
requirements in the National Emission
Standard for mercury in subpert E of 40
CFR pert 61 an met.
(f) The combustion temperatures.
including the maximum combustion
temperature, for the sewage sludge
incinerator.
(g) Values for the air pollution control
device operating parameters.
(h) The oxygen concentration and
information used to measure moisture
content in the exit gas from the sewage
sludge incinentor stack.
(i) The sewage sludge feed rate.
(j) The stack height for the sewage'
sludge incinentor.
(k) The dispersion factor for the site
when the sewege sludge incinerator is
located.
(1) The control efficiency for lead.
arsenic, cadmium, chromium, end
nickel far each sewege sludge
incinerator.
(m) The risk spedflc concentration for
chromium fialtnilattfl using equation (6)*
if applicable.
(n) A calibration and maintenance log
for the instruments used to measure the
total hydrocarbons concentration and
oxygen concentration in the exit gas
from the sewege sludge incinerator
stack, the information needed to
determine moisture content in the exit
gas. and the combustion temperatures
A-7
-------
9404
Federal Register / Vol. 58. No. 32 / Friday. February 19. 1993 / Rules and Regulations
(Approved by the Office of Management «nd
Budget under control number 2040-0157)
§S03.4a Reporting.
Class I sludge management facilities.
POTWs (as defined in 40 CFR 501.2)
with a design flow rate equal to or
greater than one million gallons per day,
and POTWs that serve a population of
10.000 people or greater shall submit
the information in §503.47(b) through
§ 503.47(h) to the permitting authority
on February 19 of each year.
(Approved by the Office of Management and
Budget under control number 2040-0157)
Appendix A to Part 503—Procedure to
Determine the Annual Whole Sludge
Application Rate for • Sewage Sludge
Section 503.13(a)(4)(ii) require* that the
product of the concentration for each
pollutant listed in Table 4 of § 503.13 in
sewage sludge sold or given away in a bag
or other container for application to the land
and the annual whole sludge application rate
(AWSAR) for the sewage sludge not cause the
annual pollutant loading rate for the
pollutant in Table 4 of $ 503.13 to be
exceeded. This appendix contains the
procedure used to determine the AWSAR for
a sewage sludge that does not cause the
annual pollutant loading rates la Table 4 of
§ 503.13 to be exceeded.
The relationship between the annual
pollutant loading rate (APLR) for a pollutant
and the annual whole sludge application rate
(AWSAR) for la sewage sludge is shown in
equation (1).
APUUCxAWSARxO.OOl (1)
Where:
APLR»Annual pollutant loading rate in
kilograms per hectare per 369 day
period.
OPollutant concentration in milligrams. ^
per kilogram of total solids (dry weight
basis).
AWSAR-Annual whole sludge application
rate in metric tons per hectare per 36S
day period (dry weight basis).
0.001»A conversion factor.
To determine the AWSAR. equation (1) is
rearranged into equation (2):
AWSAR—
APLR
CxO.001
(2)
The procedure used to determine the
AWSAR for a sewage sludge is presented
below.
Procedure:
1. Analyze a sample of the sewage sludge
to determine the concentration for each of the
pollutants listed in Table 4 of § 503.13 in the
sewage sludge.
2. Using the pollutant concentrations from
Step l and the APLRi from Table 4 of
§ 503.13. calculate an AWSAR for each
pollutant using equation (2) above.
3. The AWSAR for the sewage sludge is the
lowest AWSAR calculated in Step 2.
Appendix B to Part 503—Pathogen
Treatment T
A. Processes to Significantly Reduce
Pathogens (PSRP)
1. Aerobic digestion—Sewage sludge is
agitated with air or oxygen to maintain
aerobic conditions for a specific mean cell
residence time at a specific temperature.
Values for the mean cell residence time and
temperature shall be between 40 days at 20
degrees Celsius and 60 days at 13 degrees
Celsius.
2. Air drying—Sewage sludge is dried on
sand beds or on paved or unpaved basins.
The sewage sludge dries for a mtuimiim of
three months. During two of the three
months, the ambient average daily
temperature is above zero degrees Celsius.
3. Anaerobic digestion—Sewage sludge is
treated in the absence of air for a specific
mean call residence time at a specific
temperature. Values for the mean ceil
residence time and temperature shall be
between 15 days at 33 to 53 degrees Celsius
and 60 days at 20 degrees Celsius.
4. Composting—Using either the within*
vessel, static aerated pile, or windrow
composting methods, the temperature of the
sewage sludge is raised to 40 degrees Celsius
or higher and remains at 40 degrees Celsius
or higher for five days. For four hours during
the five days, the temperature in the compost
pile exceeds 55 degrees Celsius.
5. Lime stabilization—Sufficient lime is
added to the sewage sludge to raise die pH
of the sewage sludge to 12 after two hours of
contact
B. Processes to Further Reduce Pathogens
(PFRP)
1. Composting—Using either the within-
vessel composting method or the static
aerated pile composting method, the
temperature of the sewage sludge is
maintained at 53 degree* Celsius or higher
for three days.
Using the windrow composting method.
the temperature of the sewage sludge is
maintained at 55'degrees or higher for IS
days or longer. During the period when the
compost is maintained at 35 degrees or
higher, there shall be a •"'"'""••" of five
turnings of the windrow.
2. Heat drying Sewage sludge ls dried by
direct or indirect contact with hot gases to
reduce the moisture content of-the sewage
sludge to 10 percent or lower. Either the
temperature of the sewage sludge particles
exceeds 80 degrees Celsius or the wet bulb
temperature of the gas in contact with the
sewage sludge as the sewage sludge leaves
the dryer exceeds 80 degrees Celsius.
3. Heat treatment—Liquid sewage sludge is
heated to a temperature of 180 degrees
Celsius or higher for 30 minutes.
4. Thermophilic aerobic digestion Liquid
sewage sludge is agitated with air or oxygen
to maintain aerobic conditions and the meet!
cell residence time of the sewage sludge is 10
days at 55 to 60 degree* Celsius.
5. Beta ray irradiation—Sewage sludge Is
Irradiated with bet* rays from an accelerator
at dosages of ti least 1.0 megared at i
temperature (ca. 20 degree* Celsius).
6. Gamma ray irradiation—Sewage sludge
is irradiated with gamma rays from certain
isotopes, such a* Cobalt 60 and Cesium 137.
at room temperature (ca. 20 degrees Celsius).
7. Pasteurization—The temperature of the
sewage sludge i* maintained at 70 degree*
Celsius or higher for 30 minutes or longer.
(FR Doc. 93-2 Filed 2-18-93; 8:45 am)
BIUJNO coot eue-ei-M
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Part* 122,123, and 501
(FRL-451S-7J
National Pollutant Discharge
Elimination System Sewage Sludge
Permit Regulations; State Sludge
Management Program Requirements
AGENCY: Environmental Protection
Agency.
ACTION: Final rule: technical
amendment
SUMMARY: Under existing regulations
that establish sewage sludge permitting
and State sewage sludge program
requirements, approximately 20,000
publicly owned treatment works and
other treatment works treating domestic
sewage are required to submit permit
applications within 120 days after the
promulgation of standards applicable to
their sewage sludge use or disposal
practice(s). The final sewage sludge use
and disposal standards will be
published in the Federal Register on or
near the same date as this final rule. To
facilitate the management of these
applications, on May 27.1992. EPA
proposed to revise these rules to stagger
the submission of permit applications.
Additionally. EPA proposed to extend
the time period during which the initial
set of applications must be submitted
from 120 days to 180 days after
promulgation of the technical standards.
In response to comments received on
the May 27.1992. proposal. EPA U
issuing a final rule which requires
permit applications in phases and •
extends the time period in which the
initial applications are due following
the publication of the final use or
disposal standards.
On July 28.1986, EPA promulgated
final regulations for application
requirements for facilities that discharge
only non-process wastewater. which
resulted hi internal recodification of
§ 122.21. Conforming changes were not
made to $ 123.2S(a)(4) which refers to
the relevant portions of section 122.
These technical corrections are being
made as part of this rule.
EPFCCnvi DATE: The effective date of
this final rule is March 22.1993.
A-8
-------
APPENDIX B
SEWAGE SLUDGE INCINERATORS SUBJECT
TO PART 503
(as of October 27,1992)
-------
SEWAGE SLUDGE INCINERATORS SUBJECT TO PART 503 AS OF 10/27/92
STATE
CTTY
FACILITY NAME
STATE
NPDE&T COUNT
CT
CT
CT
CT
CT
CT
CT
CT
CT
CT
MA
MA
MA
MA
MA
MA
NH
NH
RI
NJ
NJ
NJ
NJ
NJ
NJ
NJ
NJ
NJ
NJ
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
STAMFORD
NEW CANAAN
HARTFORD
NEW HAVEN
NORWALK
VERNON
NEW LONDON
WATERBURY
NAUGATUCK
CROMWELL
FITCHBURG
MILLBURY
NEW BEDFORD
FALL RIVER
N. ANDOVER,
CHICOPEE
WEST LEBANON
MANCHESTER
CRANSTON
BRIDGEWATER
ATLANTIC CITY
PARSJJPANY
WAYNE
FAIRFIELD
THOROFARE
PRINCETON
CAMDEN
WALDWICK
UNION BEACH
NEWROCHELLE
POUOHKEEPSIE
BUFFALO
BUFFALO
ROCHESTER
HILTON
AUBURN
MECHANICVILLE
BEACON
ALBANY
STAMFORD STP
NEW CANAAN STP
THE METROPOLITAN DIST.
NEW HAVEN EAST SHORE STP
NORWALK STP
VERNON WPCF
NEW LONDON/STP
WATERBURY STP
NAUGATUCK SEWAGE TREATMENT
MATTABASSETT DIS1R. COMMISSION
EAST FITCHBURG W W T F
UPPER BLACKSTONE W P A D
NEW BEDFORD W T P
FALL RIVER STP
GREATER LAWRENCE SD WWTP
CHICOPEE W P C
LEBANON W W T F
MANCHESTER W W T F
CRANSTON WWTF
SOMERSET RARTTAN VALLEY S A
ATLANTIC COUNTY UTIUTIES
PARSIPPANY TROY HILLS
MOUNTAIN VIEW STP
TWO BRIDGES SA-PEQUANNOCK LIN
GLOUCESTER COUNTY UA
STONY BROOK REGIONAL SA
CAMDEN COUNTY MUA **
NORTHWEST BERGEN COUNTY UA
BAYSHORE REGIONAL SA
NEW ROCHELLE S.D.-WESCHESTER C
ARLINGTON STP-POUGHKEEPSffi
ERIE CO/SOUTHTOWNS SEW TRT
BUFFALO BIRD ISLAND WWTP
MONROE CO-GATES-CHILI-OGDEN S.
MUNROE CO-NORTHWEST QUAD.PUR
AUBURN (C) STP
SARATOGA CO SDf 1 WWTP
BEACON (C) WTP
ALBANY CO SD NORTH WWTP
CT0101087
CT0101273
CTO 100251
CT0100366
CT0101249
CT0100609
CTO 100382
CTO 100625
CT0100641
CT0100307
MA010098
MA010236
MAOL0078
MA010038
MA010044
MAO 10 150
NH0100366
NH0100447
RI0100013
NJ0024864
NJ0024473
NJ0024970
NJ0028002
NJ0029386
NJ0024686
NJ0031119
NJ0026468
NJ0024813
NJ0024708
NY0026697
NY0026271
NY0095401
NY0028410
NY0028045
NY0028231
NY 0021903
NY0028240
NY0025976
NY0026875
— j
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
1
2
1
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10
REG
01
01
01
01
01
01
01
01
01
01
01
01
01
01
01
01
01
01
01
02
02
02
02
02
02
02
02
02
02
02
02
02
02
02
02
02
02
02
02
B-l
-------
SEWAGE SLUDGE INCINERATORS SUBJECT TO PART 503 AS OF 10/27/92
STATE
STATE CITY FACILITY NAME NPDE&f COUNT
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
NY
IL
MD
MD
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
PA
VA
VA
VA
VA
VA
VA
ALBANY
PORT WASfflNGTO
ORANGETOWN
OSSINING
WATERTOWN
ROCHESTER
SCHENECTADY
PORT CHESTER
NEW WINDSOR
UTICA
WEST BABYLON
OSWEGO (C)
GLEN COVE
OSWEGO
DUNKIRK
LITTLE FALLS
NORTHBROOK *
BALTIMORE
SNOW HILL
PITTSBURGH
CHESTER
LEECHBURG
DAUPHIN COUNTY
HAZELTON
WILKESBARRE
JOHNSTOWN,
NORTH WALES
WILLOW GROVE
DAUPHIN COUNTY
COLMAR
YORH_COUNTY
BLAIR COUNTY
DURYEA
NORRISTOWN
ERIE
VIRGINIA BEACH
NEWPORT NEWS
ARLINGTON
FAIRFAX
HOPEWELL
BLACKSBURG
ALBANY CO SD SOUTH WWTP
PORT WASHINGTON WPCP
ORANGETOWN (T) SD#2 STP
WESTCHESTER CO-OSSINING SD WW
WATERTOWN (C) WPCP
ROCHESTER-FRANK E. VAN LARE ST
SCHENECTADY (C) WPC FACILITY
PORT CHESTER SANITARY SD WWTP-
NEW WINDSOR (T) STP
ONEIDA COUNTY WPCP
SUFFOLK COUNTY SD03-SOUTHWEST
OSWEGO (C) EAST SIDE STP
GLEN COVE (C) WTP
OSWEGO WEST SIDE STP
DUNKIRK (C) WWTP
LITTLE FALLS (C) WWTP
UTIL OF MD-MARLBORO MEADOWS S
PATAPSCO WWTP
OCEAN CITY WTP, WORCESTER CO.
ALLEGHENY COUNTY SANITARY
DELAWARE CTY. REGL. WATER
KISKI VALLEY WATER POLLUTION
SWATARA TWP AUTH
GREATER HAZELTON SEWAGE TREA
WYOMING VALLEY STP
JOHNSTOWN CITY
UPPER GWYNEDD TOWNSHIP AUTHO
UPPER MORELAND-HATBORO SEWAG
DERRY TOWNSHIP MUN. AUTH.
HATFIELD TWP. MUN. AUTH.
YORK CITY WASTEWATER TMT PLAN
TYRONE BOROUGH SEWER AUTH-STP
LOWER LACKA WANNA VALLEY SAN.
EAST NORRITON-PLYMOUTH - STP
ERIE WASTEWATER TREATMENT
WILLIAMSBURG
HRSD - BOAT HARBOR STP
ARLINGTON STP
LOWER POTOMAC STP
HOPEWELL STP CITY OF
BLACKBURG-VPI SANITATION AUTH
NY0026867
NY0026778
NY0026051
NY0108324
NY0025984
NY0028339
NY0020516
NY0026786
NY0022446
NY0025780
NY0104809
NY0029114
NY0026620
NY0029106
NY0027961
NY0022403
MD002278
MD002160
MD002004
PA002S984
PA0027103
PA0027626
PA0026735
PA0026921
PA0026107
PA0026034
PA0023256
PA0025976
PA0026484
PA0026247
PA0026263
PA0026727
PA0026361
PA0026816
PA0026301
VA0025267
VA0025283
VA0025143
VA0025364
VA0066630
VA0060844
=====
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
1
2
3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1
2
3
4
5
6
REG
02
02
02
02
02
02
02
02
02
02
02
02
02
02
02
02
03
03
03
03
03
03
03
03
03
03
03
03
03
03
03
03
03
03
03
03
03
03
03
03
03
B-2
-------
SEWAGE SLUDGE INCINERATORS SUBJECT TO PART 503 AS OF 10/27/92
STATE
CITY
FACILITY NAME
VA
VA
WV
WV
FL
FL
GA
GA
GA
GA
GA
GA
GA
GA
NC
NC
NC
SC
SC
TN
TN
TN
TN
IN
MI
MI
MI
MI
MI
MI
MI
MI
MI
MI
MI
MI
WILLIAMSBURG
PRINCE WILLIAM
HUNTINGTON
CLARKSBURG
JACKSONVILLE
PENSACOLA
ATLANTA
ATLANTA
MARIETTA
GAINESVILLE
SAVANNAH
MARIETTA
MARIETTA
STONE MOUNTAIN
ROCKY MOUNT
GREENSBORO
SHELBY
COLUMBIA
CHARLESTON
NASHVILLE
NEWPORT
MARYVILLE
BRISTOL
INDIANAPOLIS
WYANDOTTE
PORT HURON
LANSING
GRAND RAPIDS
FLINT
YPSILANTI
EAST LANSING
TRENTON
ANN ARBOR
WARREN
DETROIT
BAY CITY
WILLIAMSBURG WFP CITY OF
MOONEY STP
CITY OF HUNTINGTON
CLARKSBURG SANITARY BOARD
JAX BUCKMAN ST STP #1
ESCAMBIA CNTY-MAIN STREET WTP
ATLANTA-R M CLAYTON WPCP
ATLANTA- UTOY CREEK WPCP
COBB CO.-SO. COBB WPCP
GAINESVILLE FLAT CR WPCP
SAVANNAH PRESIDENT ST. WPCP
COBB CO - NOONDAY CREEK WPCP
COBB CO-SUTTON WPCP
DEKALB CO-SNAPFINGER CR WPCP
ROCKY MOUNT (TAR RIVER WWTP)
GREENSBORO T. Z. OSBORNE WWTF
SHELBY WWTP, CITY OF
COLUMBIA/METRO PLANT
CHARLESTON/PLUM ISLAND PLANT
NASHVILLE CENTRAL STP
NEWPORT STP
MARYVILLE STP
BRISTOL STP #2
INDIANAPOLIS-BELMONT MUN. STP
WAYNE CO- WYANDOTTE WWTP
PORT HURON WWTP
LANSING WWTP
GRAND RAPIDS WWTP
FLINT WWTP
YCUA REGIONAL WWTP
EAST LANSING WWTP
TRENTON WWTP
ANN ARBOR WWTP
WARREN WWTP
DETROIT WWTP
BAY CITY WWTP
VA0056537
VA0025101
WV002315
WV002330
FL0026000
FL0021440
GA0021482
GA0021458
GA0026158
GA0021156
GA0025348
GA0024988
GA0026140
GA0024147
NC0030317
NC0047384
NC0024538
SC0020940
SC0021229
TN0020575
TN0020702
TN0020079
TN0023531
IN0023I83
MI0021156
MI0023833
MI0023400
MI0026069
MI0022926
MI0042676
MI0022853
MI0021164
MI0022217
MI0024295
MI0022802
MI0022284
=====
7
8
1
2
1
2
1
2
3
4
5
6
7
8
1
2
3
1
2
1
2
3
4
1
1
2
3
4-
5
6
7
8
9
10
11
12
STATE
NPDE&f COUNT REG
03
03
03
03
04
04
04
04
04
04
04
04
04
04
04
04
04
04
04
04
04
04
04
05
05
05
05
05
05
05
05
05
05
05
05
05
B-3
-------
SEWAGE SLUDGE INCINERATORS SUBJECT TO PART 503 AS OF 10/27/92
STATE
CITY
FACILITY NAME
STATE
COUNT REG
MI
MI
MN
MN
MN
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
WI
WI
AR
LA
LA
LA
LA
IA
IA
IA
KS
KS
KS
MO
MO
MO
MO
NE
KALAMAZOO
PONTIAC
SAINT PAUL
DULUTH
SAINT PAUL
EUCLID
CINCINNATI
CLEVELAND
WILLOUGHBY
CINCINNATI
YOUNGSTOWN
CLEVELAND
CANTON
COLUMBUS
COLUMBUS
YOUNGSTOWN
AKRON
GREEN BAY
DEPERE
LITTLE ROCK
NEW ORLEANS
LAKE CHARLES
LAKE CHARLES
NEW ORLEANS
DAVENPORT
DUBUQUE
CEDAR RAPIDS
KALAMAZOO WWTP
PONTIAC WWTP
MWCC/MC-SENECA
WESTERN LAKE SSD
MWCC/MC-METROPOLITAN
EUCLID, CITY OF
HAMILTON CO. MILL CREEK
NEORSD - WESTERLY
WILLOUGHBY, CITY OF
HAMILTON CO.-MUDDY CREEK
YOUNGSTOWN, CITY OF
NEORSD - SOUTHERLY
CANTON, CITY OF
COLUMBUS, CITY OF-JACKSON
COLUMBUS, CITY OF - SOUTHERLY
MAHONTNG CO. BD. OF COMM.
AKRON, CITY OF
GREEN BAY METROPOLITAN SEWERA
DE PERE CITY
CITY OF LITTLE ROCK-FOURCHE WW
NEW ORLEANS -EASTBANK STP
CITY OF LAKE CHARLES B PLANT
CITY OF LAKE CHARLES C PLANT
NEW ORLEANS -WESTBANK STP
DAVENPORT CITY OF STP
DUBUQUE CITY OF STP
CEDAR RAPIDS CITY OF STP
SHAWNEE MISSION JOHNSON CO UWWD MISSION/TURK
KANSAS CITY
KANSAS CITY
ST LOUIS
INDEPENDENCE
KANSAS CITY
ST. LOUIS
OMAHA
KANSAS CITY KS PLANT *20
KC MUNIC WWTP #1-KAW POINT
ST LOUIS MSD, BISSELL POI
INDEPENDENCE-ROCK CREEK WTP
KC, BLUE RIVER
ST. LOUIS MSD - LEMAY
OMAHA PAPILLION CREEK WWTF
MI0023299
MI0023825
MN003000
MN004978
MN002981
OH0031062
OH002S461
OH0024660
OH0028126
OH0025470
OH0028223
OH0024651
OH0024350
OHC024732
OH0024741
OH0045721
OH0023833
WI0020991
WI0023787
AR0040177
LA0038091
LA0036358
LA0036366
LA0038105
IA00430S2
IA0044458
IA0042641
KS0055492
KS0038547
KS0038563
MO002S17
MO008968
M0002491
M0002515
NE0112810
=^SS=S
13
14
1
2
3
1
2
3
4
5
6
7
8
9
10
11
12
1
2
1
1
2
3
4
1
2
3
1
2
3
1
2
3
4
1
05
05
05
05
05
05
05
05
05
05
05
05
05
05
05
05
05
05
05
06
06
06
06
06
07
07
07
07
07
07
07
07
07
07
07
B-4
-------
SEWAGE SLUDGE INCINERATORS SUBJECT TO PART 503 AS OF 10/27/92
STATE CTTY FACILITY NAME
CA
CA
CA
CA
CA
CA
CA
HI
NV
AK
AK
WA
WA
WA
WA
BARSTOW BARSTOW, CA
SOUTH LAKE TAH SOUTH TAHOE P.U.D.
RED WOOD CITY SOUTH BAYSIDE SYSTEM
LAGUNA HILLS S.E.R.R.A.
PALO ALTO PALO ALTO STP
MARTINEZ CENTRAL CONTRA COSTA
SAN MATEO SAN MATEO, CITY OF
HONOLULU HONOLULU, CITY AND COUNTY OF
ZEPHYR COVE DOUGLAS CO. SEWER
WRANGELL WRANGELL, CITY OF
ANCHORAGE ANCHORAGE, PORT OF
EDMONDS EDMONDS, CITY OF
LYNNWOOD LYNNWOOD, CITY OF
VANCOUVER VANCOUVER, CITY OF
BELLINGHAM BELLINGHAM, CITY OF
ACTIVE NON EXPIRED 118
ACTIVE SLUDGE ONLY 1
EXPIRED PERMITS 47
TOTAL # ACTIVE INCINERATORS 166
INACTIVES 12
CA
CAO 102709
CA0038369
CA0107417
CA0037834
CA0037648
CA0037541
HI0020117
NV0020052
AK0021466
AK0021636
WA00240S
WA002403
WA00243S
WA002374
I,
1
2
3
4
5
6
7
1
1
I
2
1
2
3
4
STATE
NPDESf COUNT REG
09
09
09
09
09
09
09
09
09
10
10
10
10
10
10
TOTAL # INCINERATORS
178
B-5
-------
APPENDIX C
RATIO OF HEXAVALENT TO TOTAL
CHROMIUM INCINERATION EMISSION
-------
j^ . . . _,_,-,-
f» . ,'N:"v 5*1* • -3 =•'''••';?CNM5N~AL . "*-" =
C-"^^/ ; ' -vASniNGTCN. O.C. 'C-60
JUN 2 8 i9S!
MEMORANDUM
SUBJECT: Ratio of Hexavalent to Total Chromium Incineration
Emission
FROM: Helen Jacobs, Statistician, ^-V •
Statistics Section, EAD (WH-552)
TO: Alan Rubin, Chief
Sludge Risk Assessment Branch, HECD (WH-536)
THRU: Henry Kahn, Chief W£-—
Statistics Section, EAD (WH-552)
Purpose:
A statistical analysis of incinerator performance data was
conducted. The numerical values developed from this analysis will
be used as a basis for recommending limits for the maximum
proportion of hexavalent chromium in total chromium emitted during
the incineration of sludge.
Data;
Measurements of the emission levels of hexavalent and total
chromium were obtained from samples of three incinerators. At each
incinerator, sampling runs were conducted on several different
days. For a particular run, samples were taken at one or more of
the following locations in the incinerator: exiting the furnace,
exiting the scrubber and exiting the electrostatic precipitator
(ESP) . At each location two to four sampling trains located at the
same height in the stack but at different points in its
circumference were run simultaneously. The results from these
trains were averaged and this average was considered a single
observation. The results from sampling trains which did not meet
QA/QC standards were excluded from the average.
C-l
-------
/
The sites, incinerator types and the location in the stack where
the samples were taken are as follows:
_ Site _ Incinerator Type _ Location of Sample
Site 6 Multiple earth Exiting scrubber
Site 8 Fluidized bed Exiting furnace
Exiting scrubber
Exiting ESP
Site 9 Multiple hearth Exiting scrubber
Exiting ESP
Six sets of data were created - one for each site and sample
location.
Statistical Analysis;
The beta distribution was selected as the model for the proportion
of hexavalent chromium in total chromium. This distribution is
defined over the closed interval 0<=y<»l and as such is often used
as the model for proportions. The beta distribution is capable of
modeling a wide range of variation since its shape will change
markedly depending on the value of its two parameters, alpha and
beta.
The probability density function for the beta distribution is
f(y/a,p> =
= 0 elsewhere.
where
y » hexavalent chromium/ totalchxomium
The corresponding likelihood function, L, is
The maximum likelihood procedure was used to estimate the
parameters, alpha and beta, for each set of data. These maximum
C-2
-------
likelihood estimates were computed using a software routine that
utilizes the Simplex method to maximize the likelihood, L. The
software was provided by Bill Smith of EPA's office of Policy,
Planning and Evaluation.
The estimates of the means and standard deviations of the beta
distributions were calculated using the following formulas:
ab
(a+i+l) (a+i>)a
where
a,b = maximum likelihood estimates of a and f), respectively.
The maximum limit was set equal to the 95th upper percentile value
of the distributions. The pth percentile of the beta distribution
denoted by tfp, is calculated by solving the following equation for
V
where
and
a,b * maximum likelihood estimates of a and fi, respectively.
The percentiles were calculated using Statails, a software program
written by Bill Smith.
Limits were defined for each of the four combinations of furnace
types (fluidized bed or multiple hearth) and pollution control
devices (scrubber or scrubber plus ESP) . The limit for the
multiple hearth /scrubber combination represents the average values
for sites 6 and 9.
C-3
-------
Table It Descriptive Statistics on the Ratio of Hexavalent Chromium to Total
Chromium in Incinerator Emissions
O
Site
6
8
8
8
9
9
N
X -
SD -
fc -
o •
Min -
Max -
.50 -
.95 -
Location NX SD
Scrubber 5 0.0446 0.0336
Furnace 3 0.0010 0.0011
Scrubber 3 0.0103 0.0018
ESP 3 0.0208 0.0077
Scrubber 4 0.1002 0.0282
ESP 4 0.3689 0.0808
i» o Hin Max
0.0445 0.0354 0.0100 0.0958
0.0001 0.0012 0.0001 0.0026
0.0103 0.0003 0.0082 0.0125
0.0208 0.0087 0.0100 0.0273
0.1002 0.0280 0.0642 0.1433
0.3681 0.0829 0.2347 0.4464
.50 .95
0.036 0.114
0.001 0.003
0.010 0.013
0.020 0.037
0.098 0.150
0.365 0.509
Number of observations
Arithmetic mean of observations
Standard deviation of observations
Mean of beta distribution
Standard deviation of beta distribution
Smallest observed value
Largest observed value
Median (50th percentile) of beta distribution
95th percentile of beta distribution
-------
aaaults;
Six sets of data were available for analysis - one for each site
and sampling location. Appendix A contains tables of the contents
of each of these data sets. Appendix B contains the original
tables of measurements taken at the three sites from which the 6
data sets were abstracted*.
Measurements of the amounts of total chromium produced by 3 of the
sampling trains were deleted from the analysis as outliers. Site
6 had one such outlier for the scrubber exit location and site 9
had two - one at a scrubber exit and one at a ESP exit. The
determination that these results were outliers was based on the
professional judgement of a chemist employed by Entropy, one of the
contractors responsible for conducting the sampling and analysis.
The number of observations in the six sets of data ranged from 3 to
5. The site 6 scrubber exit had 5 observations; the site 8
furnace, scrubber and ESP exit locations had 3 observations each;
and the site 9 scrubber and ESP exit locations had 4 observations
each.
Estimates of the beta distribution parameters, alpha and beta, were
produced for each of the sets of data. Appendix C contains a table
of these parameter estimates.
Table I provides descriptive statistics for the proportion of
hexavalent chromium in total chromium for each sampling location
and site. Among the incinerators tested, site 9, which has a
multiple hearth furnace, showed the highest median percent of
hexavalent chromium in emissions. The median percent of hexavalent
chromium at site 9 was 9.8% exiting the scrubber and 36.5% exiting
the ESP. At site 6, also a multiple hearth incinerator, the median
percent of hexavalent chromium exiting the scrubber was 3.6%. The
third incinerator, site 8, is a fluidized bed incinerator. Results
from this site were mostly non-detection for hexavalent chromium
and, thus, the true values are less than or equal to the reported
values. The medians based on the reported values for site 8 were
1.3% exiting the scrubber and 2.0% exiting the ESP.
Table II provides the proposed maximum limits for hexavalent
chromium in total chromium emitted during sludge incineration by
furnace type and pollution control device. These limits are based
on the 95th percentilo of the beta distribution. For a fluidized
bed furnace with a scrubber the limit is 1.3% and with the addition
of an ESP the limit is 3.7%. For a multiple hearth with a scrubber
the limit is 13.2% and with the addition of an ESP the limit is
50.9%.
C-5
-------
Table 2: Proposed Emission Limitations for the Percent of
Hexavalent chromium in Total Chromium
Furnace Type
Fluidized Bed
Multiple Hearth
Pollution Control Device
Scrubber
1.3%
13.2%
Scrubber Plus ESP
3.7%
50.9%
Conclusions:
There are substantial differences with regard to the percent of
hexavalent chromium in total chromium emitted during the
incineration of sludge among different furnace types and pollution
control devices. The fluidized bed furnace had lower percents of
hexavalent chromium than the multiple hearth furnaces. And, the
emissions leaving the scrubber had lower percents of hexavalent
chromium than the emissions exiting the ESP. Given these
differences the need for separate limits for each combination of
scrubber and pollution control device appears justified.
cc: Neil Patel
Gene Grumpier
Attachment
C-6
-------
Sampling Results for Hexavalent and Total Chromium
Site 6
Location of Sample - Exiting the Scrubber
Sample
Run
3
3
3
3
Average
7
7
7
7
Average
9
9
Average
11
11
Average
13
13
Average
Cr+6
(ug/dscm)
0.15
0.06
0.03
0.005
0.06
0.17
0.15
0.16
0.10
0.15
0.18
0.29
0.24
0.31
0.38
0.35
0.04
0.02
0.03
Total Cr
(ug/dscm)
5.6
8.6
4.3
6.1
6.15
4.1
3.9
4.4
13.7 *
4.1333
3.1
3.6
3.35
3.8
3.4
3.6
2.7
2.3
2.5
Ratio of
Cr+6 to
Total Cr
0.0268
0.0070
0.0070
0.0008
0.0100
0.0415
0.0385
0.0364
0.0073
0.0351
0.0581
0.0806
0.0701
0.0816
0.1118
0.0958
0.0148
0.0087
0.0120
* Outlier not included in average.
C-7
-------
Sampling Results for Hexavalent and Total Chromium
Site 8
Location of Sample - Exiting Furnace
Run
Ratio of
Cr+6 Total Cr Cr+6 to
(ug/dscm) (ug/dscm) Total Cr
4 11.00
11.00
Average 11.00
96500
72100
84300
0.0001
0.0002
0.0001
Average
7.48
7.48
31200
31200
0.0002
0.0002
8
Average
9.92
9.92
3800
3800
0.0026
0.0026
C-8
-------
Sampling Results for Hexavalent and Total chromium
Site 8
Location of Sample - Exiting Scrubber
Sample (
Run i
4
Average
6
Average
8
Zr+6
(ug/dscm)
0.02
0.01
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.01
Total Cr
(ug/dscm)
3.0
1.4
1.7
2.03
1.5
2.9
1.5
1.97
1.2
1.5
1.3
Ratio of
Cr+6 to
Total Cr
0.0067
0.0071
0.0118
0.0082
0.0133
0.0069
0.0133
0.0102
0.0167
0.0133
0.0077
Average
0.02
1.33
0.0125
C-9
-------
Sampling Results for Hexavalent and Total Chromium
Site 8
Site of Sample - Exiting WESP
Run
4
Average
6
Average
8
Average
Cr+6
(ug/dscm)
0.03
0.03
0.02
0.02
0.01
0.01
Total Cr
(ug/dscm)
1.1
1.1
0.8
0.8
1.0
1.0
Ratio of
Cr+6 to
Total Cr
0.0273
0.0273
0.0250
0.0250
0.0100
0.0100
C-10
-------
Sampling Results for Hexavelant and Total Chromium
Site 9
Location of Sample - Exiting Scrubber
Ratio of
Sample
Run
3
3
3
Average
5
5
5
Average
8
8
8
Average
10
10
10
Cr+6
(ug/dscm)
1.4
1.3
2.3
1.67
2.5
0.6
1.4
1.5
1.0
1.3
0.9
1.15
1.2
1.8
1.4
Total Cr
(ug/dscm)
11.8
10.7
12.4
11.63
17.2
15.2
15.3
15.9
17.5
18.3
4.2 *
17.9
14.5
15.3
14.6
Cr+6 to
Total Cr
0.1186
0.1215
0.1855
0.1433
0.1453
0.0395
0.0915
0.0943
0.0571
0.0710
0.2143
0.0642
0.0828
0.1176
0.0959
Average 1.47 14.80 0.0991
=»»»»»»=»»==•==»»=»•===== = = = = ===== === = = = = = ===
* Outlier not included in average.
C-ll
-------
Sampling Results for Hexavelant and Total Chromium
Site 9
Location of Sample - Exiting WESP
Sample Cr+6 Total Cr
Run (ug/dscm) (ug/dscm)
3
3
3
Average
5
5
5
Average
8
8
8
Average
10
10
10
Average
* Outlier
N
Mean
^f & ^M X ^^MW^K
n • Ti • ^HI I^H
Maxima
Std. dev.
Alpha
Beta
Mean
Variance
Std. dev.
0.8
0.8
0.7
0.77
1.0
1.6
1.5
1.55
0.4
0.6
1.5
0.83
0.8
0.8
0.8
0.8
not included
2.6
4.0
3.2
3.27
33.9 *
3.6
3.9
3.75
1.6
1.8
2.2
1.87
2.3
2.1
1.9
2.1
in average
Ratio of
Cr+6 to
Total Cr
0.3077
0.2000
0.2187
0.2347
0.0295
0.4444
0.3846
0.4133
0.2500
0.3333
0.6818
0.4464
0.3478
0.3810
0.4211
0.3810
=========
4
0.3689
0.2347
0.4464
0.0808
12.10092
20.77726
0.368053
0.006865
0.082858
Print
File
0.2347
0.4133
0.4464
0.3810
* Outlier not included in average.
C-12
-------
Estimated Beta Distribution Parameters
Site
Site 6
Sit* 8
Site 9
Location
Exiting Scrubber
Exiting Furnace
Exiting Scrubber
Exiting ESP
Exiting Scrubber
Exiting ESP
Alpha
1.46205
0.69174
33.6712
5.59566
11.40484
12.10092
Beta
31.38569
707.59162
3239.0905
263.97016
102.38166
20.77726
C-13
-------
Estimated Beta Distribution Parameters
Site
Site 6
Sit:* 8
Site 9
Location
Exiting Scrubber
Exiting Furnac*
Exiting Scrubber
Exiting ESP
Exiting Scrubber
Exiting ESP
Alpha
1.46205
0.69174
33.6712
5.59566
11.40484
12.10092
Beta
31.38569
707.59162
3239.0905
263.97016
102.38166
20.77726
C-14
-------
APPENDIX D
SUMMARY OF NICKEL SPECIATION EMISSION TESTS AT
THREE SEWAGE SLUDGE INCINERATORS
-------
SUMMARY OF NICKEL SPECIATION IN SEWAGE SLUDGE
INCINERATOR EMISSIONS
Run No.
Soluble
pg/m3 %
Sulfidic*
//g/m3 %
Oxidic
//g/m3 %
Total
;/g/m3
Outlet - Site 6
Run 5
Run 6
Run 10
Run 12
1.6
0.9
1.1
0.7
58
42
60
39
<0.15
<0.18
<0.18
<0.20
< 5
< 8
<10
<11
1.2
1.3
0.7
1.1
42
58
40
61
2.8
2.2
~ 1.8
1.8
Inlet - Site 6
Run 5
Run 6
Run 8
Run 10
Run 12
65
98
18
65
64
41
41
21
41
77
<18
<28
< 6
19
<13
<12
<12
< 7
12
<15
92
140
66
74
19
59
59
79
47
23
157
238
84
158
83
Midpoint - Site 8
Run 5
Run 10
0.32
0.17
Run 8
Run 10
555
301
52.6
35.7
<0.065
<0.069
Inlet -
12.0
4.0
<370
<301
<10.5
<14.3
0.29
0.31
Site 8
<9.0
<3.9
3546
7377
47.4
64.3
0.61
0.52
88.0
96.0
4101
7678
Midpoint - Site 9
Run 4C
Run 9C
Run 11C
Run 12C
Run 13C
10.0
22.7
24.2
30.7
24.6
.51.1
92.2
91.4
95.5
95.5
2.2 11.4
<0.1 <0.5
<0.1 <0.4
<0.1 <0.3
<0.1 <0.4
7.3
1.9
2.3
1.4
1.2
37.5
7.8
8.6
4.5
4.5
19.6
24.6
26.4
32.1
25.8
Inlet - Site 9
Run 4C
Run 9C
Run 11C
Run 12C
Run 13C
77.0
201.0
449.1
415.6
358.5
18.1
19.2
20.5
30.4
55.8
<9.1 <2.1
<11.2 <1.1
<26.4 <1.2
<18.5 <1.4
10.5 1.6
330.6
826.4
1691
914.3
263.6
77.8
78.7
77.1
66.9
41.0
425.1
1050
2193
1367
643.1
'The sulfidic nickel is a combination of nickel sulfide and nickel
subsulfide.
Site 6 and Site 9 are multiple-hearth furnaces; Site 8 is a fluidized-bed furnace. Outlet samples
had insufficent paniculate matter to attempt an analysis
Source: Steinsberger, et al., 1992.
D-l
-------
APPENDIX E
GENERAL GUIDELINES FOR CONDUCTING A PERFORMANCE TEST AT A
SEWAGE SLUDGE INCINERATOR TO DETERMINE THE CONTROL EFFICIENCY
-------
STACK GAS SAMPLING
This section describes testing activities used 1n determining
facility-specific control efficiency values for toxic metals emissions. These
efficiency values are used to calculate the maximum allowable concentration of
toxic metals 1n the sludge feed and the maximum allowable sludge feed rate
to the Incinerator based upon the equations provided 1n the proposed rule.
The test data will also be used to determine facility-specific limits for
temperature, oxygen, and air pollution control conditions.
9
1. Test Design;
The stack test must be designed .to gather all needed Information 1n
an acceptable manner. Major elements of the testing are:
• Sampling and analysis of sludge feed for metals.
• Sampling and analysis of stack emissions for metals.
• Monitoring and documentation of operating conditions during the
test (Including temperature(s), oxygen, total hydrocarbon,
sludge feed rate, and air pollution control devices).
A few general guidelines are appropriate:
• The test should be conducted at worst case conditions (i.e.,
with the highest expected feed rate of sludge, at the highest
temperature, etc.) for metals emissions 1n order to obtain the
most flexible permit conditions. However, the system must be
operated within Its design specifications to demonstrate
adequate performance 1n controlling metals emissions.
Source: MRI, 1990
E-l
-------
All testing and monitoring must be conducted concurrently (or
phased to account for material lag time). Sludge feed samples
must be collected and analyzed to calculate an Input loading
rate for each Investigated toxic metal for comparison with
outlet emission rates.
Three replicate test runs are requested for each specific set
of operating conditions. This provides added assurance that
the Incinerator 1s operating In a consistent manner. Operating
*IT
conditions should be maintained as consistently as possible for
the three test runs.
9
Measurements of temperature, oxygen, THC, sludge feed rate* and
air pollution control Indicators should be recorded continu-
ously, or, at a minimum, every 60 sec.
All monitoring Instruments should be recalibrated Immediately
prior to and after the test. Documentation of calibrations
should be Included 1n the test report.
Sludge feed samples should be collected at least every 15 m1n
during each stack sampling test period. Individual samples can
be composited Into one sample analyzed per test run.
Sampling should not begin until the Incinerator has reached a
steady state on sludge feed. A minimum of 60 m1n (or 120 mln
for a multiple hearth) of operation feeding sludge 1s recom-
mended prior to sampling.
Minimum stack sampling time for each run (actual sampling time
not Including time for port changes, etc.) should be L hr.
Custody procedures should be used for handling all samples.
Full cha1n-of-custody procedures are typically much more labor-
intensive but may be used at the applicant's option.
E-2
-------
Results should be reported 1n a format which Includes all
Information and data necessary to calculate final results and
verify quality assurance objectives. Results should be
presented 1n as clear and succinct a format as possible.
E-3
-------
APPENDIX F
EMISSIONS DATA FOR THC, CO, AND 21 ORGANICS
FROM FOUR SEWAGE SLUDGE INCINERATORS
-------
Emissions Data for the THC, CO, and 21 Organics from Four Sewage Sludge Incinerators
SITE
1
2
3
*
5
1
2
3
4
5
6
1
2
3
1
2
3
4
5
6
7
8
9
THC
-------
Appendix F (continued)
SHE
2
2
2
2
2
2
3
J
1
4
*
4
4
4
4
4
4
4
HAPHIHAL. ACRYlOMimi BENZENE
CHIORO 1.2 DICHL
CU4 BEN1ENE CHLOROFORM OROEIHANE
1
2
]
4
5
1
2
J
4
S
A
1
2
I
1
2
3
4
5
A
7
a
9
65. A
124
85.3
0
262
A2.A
0
0
0
1.3
3.4
3.A
454
SB4
5/4
439
1073
2159
1092
3159
2594
3351
3869
0
0
0
8737
2429
8566
504
145
0
A93
B1A
4555
083
948
774
528
1287
507
283
511
573
no
4191
37
A2
7.4
902
433
2224
142
57.8
54.9
52.7
68.2
307
.1
.A
.1
.4
.8
0.4
0.31
0.44
0.4A
0.1
0
0
0
1.1
0
4.41
5.02
2.1A
0.242
0.384
0.92
0
7.18
50.7
75.5
47.A
27
69.4
29
18
19.5
53.8
43.3
33.3
0.29
0.6
0
255
102
324
5.91
2.63
0
7.11
6.35
16.3
218
214
276
226
325
0.34
0.38
1.1
0.49
0
0
244
745
4.1
0
11.4
25. 1
5.84
0.617
1.6
0.823
3.7
,13.1
0.6
0.2
0.5
0.9
4.6
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-------
Appendix F (continued)
SUE
1
1
1
1
t
1
2
2
2
2
2
2
I
3
3
4
4
4
4
i
4
4
4
4
RUN
TRAMS
1,2 OICNL EIMU HETHYIENE TETRA CHIORO 1,1,1 IRICH IRICHIORO V1NH
OROETHANE BENZENE CHLORIDE EIHENE TOLUENE LOROEIHANE El ME WE CHLORIDE
(ug/H3) (ug/M3) (ug/Nl) (ug/Ml) (ug/Ml)
-------
APPENDIX G
STATISTICAL SUPPORT FOR THE PROPOSED REGULATORY LEVEL ON
TOTAL HYDROCARBON EMISSIONS FROM THE INCINERATION OF SEWAGE SLUDGE
-------
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
OFFICE OF
WATER
MEMORANDTTM'
NOV i o "-;
SUBJECT:
FROM:
THRU:
TO:
Statistical Support for the Proposed Regulatory Level on Total Hydrocarbon
Emissions from the Incineration of Sewage Sludge
George Zipf, Statistician <^~
Statistical Analysis Section (WH-552)
Henry D. Kahn, Chief
Statistical Analysis Section (WH-552)
Al Rubin, Chief
Sludge Risk Assessment Branch (WH-585)
Summary
At your request the Statistics Section has studied the data measuring Total Hydrocarbon
Emissions Adjusted to 7% Oxygen (THC7) resulting from the incineration of sewage sludge in
order to recommend a statistically defensible operational standard for THC7 emissions. This
standard is determined to be the 99* percentile of the THC7 emissions distributions based on
data from the two best multiple hearth sites under improved operating conditions. For sites that
use the unheated sample line measurement method we recommend that the operational standard
of THC7 emissions be set at 21 ppm. To account for the difference in measurement methods,
we recommend that sites using the heated sample line measurement method have an operational
standard of 31 ppm.
Data
Data woe collected at nine sludge incineration sites. All sludge incineration sites are
multiple hearth except Site 3 and Site 8, which are fluidized bed. Total hydrocarbons were not
measured at Site 5 and no THC7 data exist for this site.
G-l
Printed on Recycled Paper
-------
Total hydrocarbon measurements are multiplied by a correction factor to account for the level
of oxygen in the combustion chamber. The correction factor is 14/(21-Oj) where the Oj is the
percentage oxygen concentration at the stack outlet. Thus when the percentage oxygen
concentration is seven, the correction factor is 147(21-7), or 1. Correction for the level of
oxygen ensures that incinerators can not lower their THC concentration simply by increasing air
flow.
I. Data Measurement
The multiple hearth sites studied were operated in three different states: normal
operations, improved operations, and operation with afterburners. A multiple hearth site under
normal operations has no special engineering supervision or additional pollution control
equipment beyond a wet scrubber. Under improved operations, professional engineers monitor
the equipment carefully, but no additional pollution control equipment is added. However, when
afterburners are added as additional pollution control equipment, the site is otherwise operated
under normal conditions, that is, without special engineering supervision.
The reason for testing emissions under improved operating conditions is that expensive
capital improvements such as afterburners may not be necessary if significant improvements can
be made through employee training. The use of afterburners tests whether THC7 emissions are
significantly reduced without changes in the multiple hearth site operations.
Samples were taken at the inlet, which is before the air pollution control system (APCS),
or at the stack outlet, which is after the APCS. However, samples taken at inlet do not
represent THC7 emissions to the air. This is because the hydrocarbons at inlet have not been
through the APCS, so that the emission levels at inlet are higher than the final emissions at
outlet. For the purposes of determining the operational standard, only outlet data were
used to support the regulation.
Sample lines carry the sample from a probe inserted in an emission stream for
measurement at a monitor. The sample lines are either heated to the temperature of the emission
stream or chilled to ambient temperature. These sample lines are called hot and cold
accordingly. Heating the sample lines prevents high boiling point organics from condensing
before measurement at the monitor. Consequently a heated sample line provides a more direct
measurement than an unhf?tf*1 sample line.
The proymtd regulation will mandate heated sample lines. However, the available data
used to develop the proposed regulation were measured cold. Therefore it was necessary to
estimate the difference between a sample measured hot and the same sample measured cold.
This nrimarinn was based on samples that were taken simultaneously with two sample lines at
the same site, one hot and one cold. We recommend that THC7 hot be ftirimatrd at 10 ppm
greater than THC7 cold. The statistical support for this figure is in a companion memorandum
to Al Rubin from George Zipf, titled 'A statistically defensible estimate of the difference
between a sample of total hydrocarbons measured with heated sample lines and the same sample
G-2
-------
measured with unheated sample lines." What is important here is that THC7 measured cold may
be used to support a proposed regulation for THC7 measured hot because the difference between
simultaneous hot and cold samples can be estimated.
n. Data Which Supports the Proposed Regulation
For data to support the proposed regulation, it must be measured at the APCS outlet.
Ideally, the data are also measured hot. Only data from sites 6, 7, 8, and 9 are measured at the
outlet. Of this data, only Site 7 has hot measurements. However, cold outlet measurements can
be used to support an operational standard based on the estimated difference as described above.
Each sample must be classifiable in only one operating condition and not be qualified in
any way. Samples taken in a transition period between different operating conditions or
qualified with event flags such as "plant not operating" or "monitor failure," were discarded.
Thus data may be grouped for analysis if they are site-specific, operations-specific,
location-specific, and sample line-specific. Table 1 below summarizes the data by site, by
operation, by location, and by sample line. The table includes the percentiles corresponding to
20 ppm, 25 ppm, and 30 ppm and the THC7 emissions levels corresponding to the 90*, 95*,
and 99* percentiles.
Methodology
No distributional assumptions are made about the data in any site-specific operations-
specific category. This is because each site-specific operations-specific group has at least 439
data points, which should be sufficiently large to approximate the true cumulative density
function. The 99* percentile of the best distribution^) of site-specific operations-specific
data is selected as the statistically supportable operational standard of THC7 emissions.
The best distribution is simply defined as having die lowest THC7 measurements, and is not
based on any engineering review. This also assumes that the proposed regulation will specify
compliance on the basis of samples measured in the same way as the supporting data.
G-3
-------
TA8LC 1: SMUT Of TOTAL HTMOCAMOH EMISSIONS ADJUSTED TO 7X OXTON
DT siTt AMD OPOATIM CONDITION*: SAMPLE SIZES AMD ENPIIICAL MKUTILES
ALL SITES AM NULTIPU NEMTH IMLESS OTHERWISE SPECIFIED IH TNB GNUTIIM CONDITIC
DATA 00(8 MT INCLUM SAMPLES THAT AM QUALIFIED.
SAMPLE LIHfS
SITE OPCMT1H6 CONDITIONS AND LOCATION
20
for
30
ppi at P«re«ntUt
90X 95X 991
SITE 1
HOT IHLCT 2425 69.6X SS.5X 91.91 28.5 32.7 44.9
SITE 2
HOT IHLBT
972 35.« 4.31 52.91 78.4 54.0 109
SITE 3 FLUIOIZED KD
HOT (HUT 1017 97.7X 97.91 M.4X 6.1 8.1 54.4
SITE 4 MOMAL COLO IHLET 2444 16.6X 19.31 21.4X 730 833 933
S*B>1«-1,2,5.6,7,9
HOT IHLET 1197 31.81 39.3X 37.9X 303 448 709
COLO IHLET
381 73. OX 79. OX M.1X 34.8 41.8 66.8
COLO INJT 899 72.1* 73.091 74.71 74.1 125 326
HOT INJT 899 69.3X 71.91 73.4X 82.6 127 378
SITE 6
COLD OUTLET 909 3.91 10.7* 24.01 63 98 193
COLD OUTLET 65S 98.6X 100.0X 100.OX 17.7 18.5 21
SITE 7
COLD OUTLET 439 O.OX O.OX O.OX 205 244 327
HOT OUTLET 439 O.OX O.OX O.OX 217 266 351
SITE 8 FLUIOU
COLD OUTLET
769 100.0X 100.01 100.01 4.6 5.1 8.3
SITE 9
••1,2.3,4.5
COLD OUTLET 1399 1.1X 4.71 8.0K 390 503 1194
COLO OUTLET
1512 98.81 99.31 99. 7X 15.9 17.2 20.3
G-4
-------
Results
As can be seen from Table 1 above, the 99* percentile for Site 6 under improved
conditions is 21 ppm cold, and for Site 9 under improved conditions is 20.3 ppm cold. Thus
at two different multiple hearth sites it is possible to keep THC7 emissions down to 21 ppm cold
99% of the time, without additional pollution control equipment. These levels are dramatically
lower than the same sites under normal operations.
It should also be noted that the fluidized bed incineration site (Site 8), easily passes the
21 ppm level. In feet, the maximum outlet THC7 emissions measurement for the 769 Site 8
observations is 9.2 ppm.
Conclusions
We recommend an operational standard of 21 ppm for THC7 when measured cold from
outlet. This figure should be raised to 31 ppm for THC7 emissions measured hot. This is based
on data for multiple hearth incineration sites. Fluidized bed sites should easily achieve the
proposed regulation limits.
cc: Neil
Bob South worth
G-5
-------
APPENDIX H
A STATISTICALLY DEFENSIBLE ESTIMATE OF THE
DIFFERENCE BETWEEN A SAMPLE OF TOTAL HYDROCARBON EMISSIONS
MEASURED WITH HEATED SAMPLE LINES AND THE SAME SAMPLE
MEASURED WITH UNHEATED SAMPLE LINES
-------
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, O.C. 20460
OFFICE OF
WATER
MEMORANDUM
NOV I 0 ••---
SUBJECT:
FROM:
THRU:
TO:
A statistically defensible estimate of the difference between a sample of total
hydrocarbon emissions measured with heated sample lines and the same sample
measured with unheated sample lines
George Zipf, Statistician
Statistical Analysis Section (WH-552)
Henry D. Kahn, Chief
Statistical Analysis Section (WH-552)
Al Rubin, Chief
Sludge Risk Assessment Branch (WH-585)
At your request the Statistics Section has studied the data measuring Total Hydrocarbon
Emissions Adjusted to 7% Oxygen (TnC7j resulting from the incineration of sludge when the
emissions are simultaneously measured with heated sample lines (hot) and with upVa***! sample
lines (cold) in order to estimate a statistically defensible difference between the two. Statistical
support for the proposed regulation requires estimation of (Hot THC7 - Cold THtrT) because
the proposed regulation specifically nun^m** ty?mt4 sample M***^ while the available data used
to support an operational standard are measured cold. We recommend that the difference
between a sample of hydrocarbon emissions adjusted to 7% Oj measured hot and the same
sample measured cold, (Hot THC7 - Cold THC7) be nrtmafrd at 10 ppm.
A sample is taken by a probe inserted into an emissions stream and carried by sample
lines to a monitor. The sample lines are either heated to the temperature of the probe location
or chilled to ambient temperature. The probe is inserted either at the inlet to the air pollution
control system or the incineration stack outlet.
H-l
! Printed on Recycled Paper
-------
In theory, a THC7 sample measured hot is always greater than ooe measured cold
because heating the sample lines prevents high boiling point organic* from condensing before
measurement « the monitor. Thus a heated sample line provides a more direct measurement
than an nnhratrri sample line. Furthermore, because the cold system condenses a fraction of the
hydrocarbons, the absolute difference between a THC7 sample measured hot and the same
sample measured cold should increase as the true emissions level increases. Thus the difference
in measurement between hot and cold samples is ftxpected to be less at regulatory levels than
when a plant is in violation.
In practice, measurement variability, sampling variability, and random error affect the
recorded value of THC7, which in turn affects the difference between hot and cold samples.
In fact, many of the observed sample differences are negative, which is theoretically impossible.
We therefore recommend that the estimate of (Hot THC7 • Cold THC7) be conservative.
That is, that the estimate of (Hot THC7 - Cold THC7) have a high probability of exceeding
the actual difference.
Data
Simultaneous hot and cold measurements exist for the first five sampling days at Site 4
and all sampling days for Site 7. Site 4 is inlet data and Site 7 is outlet data.
It was judged that inlet and outlet data should not be combined in the analysis because
scrubbers might preferentially remove semi- and non-volatile organics. Thus the difference
between hot and cold measurements is likely to be greater at inlet than at outlet, although the
available data do not support estimation of this difference. It was also judged that data should
not be combined across operating condition*, as differences might be greater or Vwft depending
on operating efficiency. Thus the data was grouped into: Site 4 Normal Operations (sample days
1, 2, and 5), Site 4 Afterburners (sample days 3 and 4), and Site 7.
The lowest emission readings are at Site 4 Afterburners, with roughly 70% of both the
hot measurements and the cold measurements less than 20 ppm. Since the best estimate for the
difference in the measurements at regulatory level should be based on data in or near the
regulatory range, only Site 4 Afterburners are used in this analysis. The emissions levels from
Site 4 Normal Operations and from Site 7 are too high to accurately estimate the difference
between hot and cold THC7 at regulatory levels. It is true that the Site 4 Afterburners data are
measured at inlet However it is judged preferable to use inlet data in and near the regulatory
range than oudet data at high emission levels. There are 899 measurements for sample days
three and four at Site 4.
H-2
-------
The difference between hot and cold measurements is «*ttifnatpi1 with two different
methodologies. The first methodology uses percentiles of the empirical distribution of the data.
The second methodology uses linear regression analysis with confidence intervals. The data
used in both methodologies are the 899 measurements from Site 4 Afterburners.
Methodology 1: Using the 90^ Percentile of (Hot THC7\ - (Cold THCT^
A variable D, is created such that D, * (Hot THC7), - (Cold THCT),, where i is the i*
paired observation. No distributional assumptions are made about D, because 899 observations
should be sufficient for the sample density function to approximate the true cumulative
distribution function.
Because the estimate of the difference between a sample measured hot and the same
sample measured cold should be conservative, the issue then is to choose a sufficiently high
percentile so that the actual difference has a high likelihood of being less. The 90* percentile
of D, is chosen as this level. At this level, ninety percent of the differences between
simultaneous hot and cold measurements are expected to be less.
Results for Methodology 1
The 90* percentile is 10 ppm. That is, a sample measured hot will be up to 10 ppm
greater than the same sample measured cold 90% of the time.
The table below gives several percentiles.
The Frequency Distribution for (Hot THC7 - Cold THC7)
Percentiles
ppm
1%
-13
25%
-1
50%
0.5
75%
5
90%
10
95%
16
99%
38
Methodolog 2: Regre*t<
f THC7 Wat
Cold
A plot of THC7 Hot against THC7 Cold for the 899 Site 4 observations suggests a linear
relationship where THC7 Hot is generally slightly greater than THC7 Cold (see plots below).
This is consista! with the theory that THC7 Hot should always be greater than THC7 Cold.
The variance appears constant up to THC7 (Hot or Cold) equals 100 ppm, and then increases.
Fortheregi
on analysis, the 72 observations where THC7 Hot and/or THC7 Cold are
greater than 100 ppm were T?ii4H from the data set because they introduce non-constant
variance and are well above the regulatory range of 20 ppm. This leaves 827 observations
containing both hot yd cold '1UC7 measurements.
H-3
-------
The regression equation gives the best linear unhiamd estimator for THC7 Hoc for a
given THC7 Cold within the appropriate range. Furthermore, regression analysis allows for
confidence intervals on the estimate of THC7 Hot, for a given level of THC7 Cold. The
methodology then is to choose as a statistically supportable level of THC7 Hot the upper limit
of the range which has a 90% chance of containing the true THC7 Hot, given THC7 Cold equals
20 ppm. The range is chosen such that there is only a 10% chance that the true THC7 Hot is
greater.
Results for Methodology 2
The regression model is csrimafprf as:
THC7 Hot, - -0.1802 + U218«(THC7 Cold), + e,
The F-test for the regression is highly significant and rs»0.9672. The regression model
fits the data well.
At THC7 Cold equals 20 ppm, the regression estimate for THC7 Hot is 22.3 ppm. Then
27.9 ppm is the upper limit of the range defined in the methodology. That is, mere is a 90%
chance that the true THC7 Hot is below 27.9 ppm.
Both methodologies support an operational standard of 30 ppm for THC7 Hot As both
methodologies are A***P*+A $o that the true THC7 Hot is not likely to be higher, this estimate
is conservative.
cc: Neil Paid
Bob Southworth
H-4
-------
600
SOO
N
e
400
T
H
C
300
7
X
0
*
y
g too
100
Sit* 4 - THC7 I Mot A Cold)
Plot of THC7HOWHC7. Legend: A = 1 ob», B = t obm. etc.
14:31 Thursday. July 30, 1992 1
A A
A A
0 *
100
too
300 400 500
Cold TMC at 7X Oxygen
600
700
000
NOTE: 537 ob« hldctan.
-------
SiU * - THC7 (HOT t COLO) < 100
Plot of THC7HOWHC7. Ugmdi A > 1 ob». B * t ot». ate.
14:31 Thursday. July 10. 1992 3
100
ao
H
e
t
T
H
C
60
0
M
y
o
to
B A 0
AA CA A A
A CAAAB AA
A
A A
A AABB
AAA COB
AA AAA B
0 *
ELJBMir BO
--*-
to
—»-
30
--*-
to
—»-
70
--t-
60
— t —
100
10
90
Cold THC «t 7X Oxygm
NOTE: 220 oto hiddwt.
-------
APPENDIX I
MOLECULAR WEIGHTS AND RESPONSE FACTORS FOR
ORGANIC COMPOUNDS USED TO DEVELOP A q,* FOR THC
-------
Average MW and Average Response Factor
t
Carcinogens
Acrylamide
Acrylonitrile
Aldrin
Ani line
Benzene
Benzidine
3enzo(a}pyrene
Bis(2-chloroethyl)ether
9
-------
Average MW and Average Response Factor
I
Carcinogens
gantna- Hexach 1 orocyc I ohexane
Hexachlorocyclohexane, technical
2,3,7,8-Hexachlorodibenzo-p-dioxin
other-Hexachlorodibenzo-p-dioxin
Hexach I oroethane
3-Methylchlolanthr«ne
Methylene chloride
^4,4-M«thylen«-bis-2-chloro«nilin« •
Methyl hydrazine
2-Nitropropane
M-Nitrosodi-M-butytamine
M-Mitrosodi-N-propytamine
N-Mitrosodietnylamine
N-Mitrosodimethylamine
N-N< trosopyrrol idine
PCS*
2,3,7,8-pentachlorodibenzo-p-dioxin
other-pemachlorodibenzo-p-dioxin
Pentach I oroni trobenzene
Pronamide
Reserpine
2,3,7,8-Tetrachlorodibenzofuran
2,3,7,8-Tetraehlorodibenzo-p-dioxin
other -Tetrachlorodibenzo-p-dioxin
1 , 1 ,2,2-Tetrachloroethane
TetracMoroethytene
Thiourea
Toxaphene
1.1,2-Triehloroetfwm
Trichloroethylent)
2,4,6-Trichlorophenol
Non- carcinogens
AcetonitrU*
Acetophenon*
Allyl alcohol
Bromodichloromthan*
Bromofon*
MW
290.35
290.35
391
391
236.74
268.34
34.94
267.16
46.07
39.09
153.24
146.24
102.14
74.08
96.09
292
3S6.S
356.5
295.36
256.13
608.7
306
322
322
167.86
165.85
76.12
413.81
133.42
131.4
197.46
41.05
120.15
58.08
163.83
252.77
95X Emission
Concentration
(ng/L)
0.1
0.1
0.00048
0.062
0.77
0.1
83.75
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
234.65
0.000136
0.00319
0.1
0.1
0.1
0.0037
0.0000762
0.00716
0.1
228.77
0.1
0.1
0.1
120.21
0.1
281.0
0.1
0.1
0.1
0.1
Fraction
Present
1.776-06
1.776-06
9.04E-W
3.90E-08
1.36E-OS
1.776-06
1.48E-03
1.776-06
1.776-06
1. 776-06
1.776-06
1.776-06
1.776-06
1.776-06
1.776-06
3.54E-06
2.48E-09
6.031-08
1.776-06
4.54E-M
1.776-06
6. 566-08
1.426-09
1.336-07
1.776-06
4.056-03
1.776-06
1.776-06
1.776-06
2.136-03
1.776-06
5.256-03
1.776-06
1.776-06
1.776-06
1.776-06
Average
MW
5.156-04
5.156-04
3. 536-06
1.526-05
3.23E-03
4.76E-04
1.266-01*
4.73E-04
8.176-09
1.586-04
2.806-04
2.596-04
1.816-04
1.316-04
1.706-04
1.046-03
8.8S6-07
2. 156-09
5.236-04
4.546-04
1.086-03
2.016-05
4.576-07
4.28E-05
2.988-04
6.726-01
1.356-04
7.336-04
2.366-04
2.806-01
3.506-04
2.161-01
2.136-04
1.036-04
2.906-04
4.486-04
Response
Factor
6.00
6.00
11.50
11.50
1.28
21.00
0.90
11.80
0.40
3.00
7.25
6.25
2.65
1.25
3.25
12.00
11.50
11.50
5.00
10.95
30.25
11.75
11.50
11.50
1.20
1.10
0.40
1.50
1.50
5.40
1.30
7.00
2.30
0.76
1.00
Average
Response
Factor
1.06C-05
1.06E-05
1.046-07
4.486-07
1.756-05
3.72E-05
1.346-03
2.096-05
7.096-07
5.32E-06
1.236-05
1. HE-OS
4.706-06
2.226-06
5.766-06
4.2S6-05
2.856-08
6.936-07
8.366-06
1.946-05
5.366-05
7.716-07
1.636-08
1.536-06
2.136-06
4.466-03
7.096-07
0.006*00
2.666-06
3.206-03
9.576-06
6.836-03
1.246-05
4.086-06
1.35E-06
1.776-06
(continued)
1-2
-------
Average MW and Average Response Factor
t
A«>0«V-
Carcinogen*
Bromomethane
2-chloro-1.3-butadiene
Cresols
Ol-n-butyl phthalate
0 i bromoch I oromethane
0 i ch lorodi f luoromethane
2,4-Ofchlorophenol
1,3-Otchloropropene
Of ethyl phthalate
Dimethoate
2,4-Oinitrophenol
DiphenylaMin*
Endosulfan
Endrin
Ethylbenzene
Formic acid
Hexaehlorocyclopentadiene
Hydrogen cyanamide
Isobutyl alcohol
Isophorone
Methomyl
Methoxychtor
Methyl ethyl ketooe
Methyl parathion
Nitrobenzene)
Pentachlorobenzene
Pentachlorophenol
Phenol
N -pheny I enedl Mint
Phenylmercurie acetate
Pyridine
Selenourea
Strychnin*
1.2,3,4,5-TetracMorobenzene
2.3,4,6-Tetrachlorophenol
Tetraethyl lead
Toluene
MW
94.95
38.54
108.13
278.34-
208.289
120.92
162
110.98
222.23
229.28
184.11
169.22
406.95
380.93
94.16
46.02
272.77
42.04
74.12
138.2
162.2
345.65
72.1
263.23
123.11
250.34
266.35
94.11
108.14
336.75
79.1
123.02
334.4
215.89
231.89
323.45
92.13
95X Emission
Concentration
-------
Average MW and Average Response Factor
I
Carcinogens
1 ,2,4-Trichlorobenzene
1,1,1 Trichloroethane
Tr i eh lorof luorcmethane
2,4,5-Trichlorophenol
C1 Hydrocarbons
C2 Hydrocarbons
Note: Methane was assuned for C1
MW
181.46
133.39
137.38
197.45
16
30
Hydrocarbons
95X Emission
Concentration
-------
APPENDIX J
CALCULATIONS TO DERIVE SITE-SPECIFIC RISK-SPECIFIC CONCENTRATIONS
AND RISK LEVELS AT THE 23 SEWAGE SLUDGE INCINERATORS IN THE
NATIONAL SEWAGE SLUDGE SURVEY
-------
Append!* J
Calculation! to Derive SUc-Spodfk Hiik-Spcdrtc Concentration! and K»k Levdi id Iht 23 Sewugc Sludge Incinerators In (he Analytical Survey of the 1988 NSSS
Variable
DF
DQI6C
DQ16E
DAJLYTP
DQ16F
SOLIDS
PCTWET
XOO
XOI
X02
X03
X04
X05
X06
X25
X08
X09
XI9
XIO
XI2
XI3
XI7
Xll
X23
X26
X29
X20
X21
Xll
THC
DF
OF
SOF
SF
VF
VGHC
FGF
FR
FC
RSC
BW
qluar
la
RL
= = = = =
Title
Diipenion Factor
Annual Throughput
Number of Dayi Opened. 198S
Daily Throughput
Percent Volatile Solid.
P Jumuyul jy*lal nil aitarul |h u • it *llllaV«
D)Reponed/A«umed PercM MouMe Coattal
Wei Feed
Moisture Fraction
Alb Solid! Fraction
Heal Value of Combustibles
Total Air Fraction. Sludge Combustion
Coaling Air Waded
Desired Outlet Temp
Radiation Lou Fraction
Solldi (Dry Feed Rate)
Combustible butt
Dry Gat From Sludge
Moisture from Sludge Combuulon
Strtcnlomeuic CombuBlon Air
Total Air, Sludge CombuBlon
Moisture Produced Without Fuel OU
HeatLouei
Incinerator Outlet Without Fuel OU
Dry Gas Flu Exocu Air
Indnerauw Outlet Wltkout Fuel OU
Enthalpy. Dry Gas at Inda. Outkl
Eataalpy. Uoiiture « beta. Outlet
Fuel OU Required
MM. Allowable ronorairalloo of THC la em
Dlapenioo Factor
M**H"f Sewage Sludge <>"'«'iiV~ GM F
Annual Average Daily Sludge Feed Rak.
Annual Average VolatUe Solid. Fraction
Annual Average Heal Value of Volatile!
Fuel Combustion Gai Flow Rale
Average Annual Dally Fuel Usage Rale
Fuel Constant
Riik Specific Concent ration
Body Weight
Cancer Potency
Inhalation rate
Risk Level
= c = = = = = = = = = ss = =ss= = » = = = =
Unili
ug/m"3/g/tec
dry UStoa/yr
dayi
dry USttos/day
unllleu
unltiess
wet IbAr
unitleu
unitleu
BTU/lb
unilieu
Ib/hr
degF
Unllleu
Ib/hr
BTU/hr
IbAr
KVhr
IbAr
IbAr
IbAr
BTUAr
BTU/hr
IbAr
degF
BTU/lb
BTU/lb
galAr
ulouppm
•HtMletMa*
low Rag-moles/day
dml/day
unilku
kcal/g
g-molet/day
Ib/day
g-motes/lb
ug/m"3
kg
(mg/kg bw/day)'-!
m-3/day
unilless
= = = = = = = = = = = = = = 5553 = 3
POTW
City
Formula/ Assumption
Abl Associates calculations
From NSSS Pan D
From NSSS Pan D
DQ16C/DQ16E
From NSSS Pan D
From NSSS' SAIC's 'Hf*** DISPOSAI^DRYWT)
100 -SOLIDS
(DQ16C • 2000 IbAon) / ((DQ16E * 24 brs op/day )*<1-(DQI6G/10
DQ16G / 100
1-VotaUe Solids/ 100
Auume 10,000 BTU/lb
Auume MH = 2.50. FB = 1.50
Auume 0 wasted air
Auume MH = 900 degree! F.FB= 1400 degrees F
Assumes *lou: 0.05
XDO- XOI • XOO
XD8«XD3*(1-X02)
X09* 0.0007494
X09* 0.0000568
XIO + XOO • XOI -r- Xl» + X08 • X02 - XOO
X12*X04
X13 • 0.01 + XIO -r XDO • XOI
XD9 • X2S -f XDt • XD2 • 130 •«• XD5 • 94 -f XI3 *970 <0.01
X09-XI1
X13 - X12 -»• XI9
(X26 • 22- 1010 • XI7 4- X09 - XI 1V00.26 • X26 -M).5 • X17)
X06 '0.26-22
X06 • 0.5 -r 1010
UAX (0. (X21 • X17 + X20»X76-X23)/ (135084 -X06« 37.5
Assume 30 ppm
GF • SGF + FGF
SGF = SF • VF • VEHC • 70.100
Dry feed In dm/day
DQI6F/100
10.000 BTU/lb • 0.0005543 to gel kcal/g
FGF • FR • FC
FR = X18 Convened to Ib/d PCI8 galAr • 24 bra/day • 6.6 lb/g«IJ
Assume f2 Fuel OU: 324.8
RSC = (THC • DF • GF / 3.240.000.000)
Auume 70 kg
Auume 1.2 * 10'-2
Auume 20 cu meien/day
RL = RSC * ql star • la / (BW • 10'3)
: = c =: = = = = = = =: = = = = = = = = = = =s = = = = = = = = = = = = =
13-23-212
Detroit
0.42
141.565.00
2.203.00
626.88
65.00
76.00
217.666.20
0.76
0.35
10.000.00
2.50
0.00
900.00
0.05
52.239.89
339.559.265.58
254.465.71
19.286.97
239.796.75
599.491.88
190.708.19
25.169.949.41
314.389.316.17
614,160.84
530.46
212.00
1,460.00
930.06
100.00
042
191 785 256 88
143,935.209.10
569.89
0.65
5.54
47,850,047.79
147,321.58
324.80
2.49
70.00
0.01
20.00
8.52E-06
===========
13-24-221
St. Paul
1.37
66.000.00 (a)
NA
540.00
77.00
67.00
136.363.64
0.67
0.28
10.000.00
2.50
0.00
900.00
0.05
45.000.00
324.000.000.00
242.805.60
18.403.20
228.808.80
572.022.00
115.487.06
23.386.613.40
300.613,386.60
586.018.80
936.96
212.00
1.460.00
0.00
100.00
1 37
137.339.818.04
490.91
0.72
5.54
0.00
0.00
324.80
5.81
70.00
0.01
20.00
I.99E-05
==========
(a) The total throughput for POTW 221 ii taken from ill calculated dry weight fired in Kwagc iludge incinerators und it not caJuculued from iu annual throughput vuluc UQI6C.
(b) Moinurc Content (ItTWtT) it determined by the percent wlidt repotted by the IOTW or calculated by SAIC during ill data consistency checks.
Source: EKG estimates based on 1V88 National Sewage Sludge Survey, lil'A
-------
Appcndii J
Calculation! to Derive
Site-Spcculc WU-Specific Caocenlnulani iind Rj«k Leveb at (he 13 Sewage Sludge Indncrolon In Ihe Analytical Survey of Uw 1988 NSSS
Title
Annual Throughput
Number of Dayi Operated, 1988
Dally Throughput
Percent Volatile SolicU
Wet Feed
Moinure Fraction
Ath Solldi Fraction
teat Value of Cotabuniblu
Total Air Fraction, Sludge CombuMion
CooUag Air Waned
Desired Outlet Temp
Radiation Low Fraction
Solidi (Dry Feed Rale)
Combuaibk Inlet
Dry Gai From Sludge
Moimire from Sludge Combuuion
Staichlameuic Canbuaiaa Air
Total Air. Sludge Combuukio
Moiiturc Produced Without Fuel Oil
Heat Lout*
Incinerator Outlet Without Fuel Oil
Dry Gat Plui Eiccw Air
lad aerator Outlet Without Fuel Oil
Enthalpy. Dry CM at Indn. Outlet
Enthalpy. MoUuiic at bda. Outlet
Fuel Oil Required
Uta. Allowable Coaorarakin of THC IB ealnloai
Dbpenloa Factor
MnuBtia Coaibuitloa Oa. Flo» Rate
Anaual Averaae Dally Sludge Feed toe
AaoBal Average VotaJlk SoUdt Fraction
AnaaaJ Avenge He* Value of VoMlt)
Fuel COBbiudao Om Flow Raw
Average Annual Daily Fuel Utage Raw
FaclCocaXaat
Body Weight
Inhalation rate
13-36-317
Cuyaboca
44.056.00
1.100.00
160.20
44.00
30,341.60
0.56
10,000.00
2.50
900.00
0.05
13.350.30
74.761.696.97
56.026.42
4,24646
52.796.71
131,991.78
22.557.68
5.782.042.41
68.979.654.56
135.221.48
1,058.89
212.00
1.440.00
0.00
100.00
4.02
31.690.610.67
31.690,610.67
145.64
S.54
0.00
0.00
324.80
20.00
»==«=«=== = = =
13-36-319
Cincinnati
14.27
28.766.00
1.102.00
104.28
55.00
29.00
71.00
29.966.80
0.71
0.45
10.000.00
2.50
900.00
0.05
8.690.37
47.797.044.77
35.819.11
2.714.87
33,754.27
84.385.6J
24,835.16
3.716.780.11
44.080.264.66
86.450.51
598.91
212.00
1.440.00
103.48
100.00
14.27
25,594.905.08
20.260,609.35
94.80
5.54
5.334.295.72
16.423.32
324.80
20.00
3.86E-05
^ s = c S£ a a s s
13-39-351
PUUburgh
0.30
24.250.00
464.00
96.81
68.00
25.00
75.00
32.271.21
0.75
0.32
10X100.00
2.50
0.00
900.00
0.05
8.067.80
54.861XM9.il
41.11287
3.116.11
38,742.87
96.tS7.lt
28.288.08
4,011,187.66
50.842.t61.45
99J27.lt
612.24
212.00
1.440.00
113.43
100.00
0.30
29.090,531.49
23,254.958.34
88.01
0.68
5.54
5,835,573.15
17.966.67
324.80
0.27
70.00
0.01
20.00
23-05-011
Martinez
- — — _ = ..s = s=_
9.19
12.950.00
366.00
69.25
76.00
24.043.48
0.76
0.76
10,000.00
2.50
0.00
900.00
0.05
5.770.44
13.849.044.83
10.378.47
786.63
9.780.20
24.450.49
19.304.18
1,499.740.99
12.349.303.84
25,048.77
(408.10)
212.00
1.460.00
208.67
100.00
9.19
16,606.050.52
5.870.448.45
62.95
0.24
5.54
10.735.602.07
33.052.96
324.80
4.71
70.00
0.01
20.00
23-07-040
Waurbury
6.89
5.580.00
301.00
78.00
7,022.05
0.22
10,000.00
0.00
900.00
0.05
1,544.85
12.049.S33.89
9.030.15
684.43
8,509.59
21.273.98
6.374.37
853.032.04
11.196.801.85
21.794.53
591.63
212.00
1.460.00
26.94
100.00
6.89
6.493.942.93
5.107.783.93
16.85
0.78
5.54
1.386,159.00
4.267.73
0.01
4.73E-06
23-10-051
Pcnutcola
3.26
6.705.00
340.00
73.00
18.00
82.00
9.129.90
0.27
10.000.00
0.00
900.00
0.05
1.643.38
11,996.691.18
8.990.32
681.41
8.472.06
21.180.16
8.379.73
862.964.81
11.133.726.36
21.698.42
320.15
212.00
1.460.00
56.26
100.00
3.26
7.979,586.20
5,085,257.36
0.73
3.M
2.894.328.85
8.911.11
0.01
2.75K-06
23-I1W2
Dccoiur
Electric Furnace
2SSS=:s = = = = =:
23.43
40.00
365.00
0.11
35.00
35.00
26.09
0.65
0.65
10,000.00
2.50
0.00
900.00
0.05
9.13
31,963.47
23.95
1.82
22.57
56.43
19.34
2.917.25
29.046.22
57.81
436.60
212.00
1,460.00
100.00
23.43
19.360.43
13.548.94
0.35
5.54
5.811.49
17.89
0.01
0.01
4.80E48
23-11-4176
= =SS=S = SS = £S =
0.79
17.986.00
600.00
55.00
21.00
23.791.01
0.79
0.45
10.000.00
2.50
0.00
900.00
4.996.11
27.478.611.11
20,592.47
1,560.79
19.405.40
48.513.49
20.840.81
2.136.783.89
25J41.827.22
49.700.56
230.74
212.00
1.460.00
100.00
0.79
19.579.456.17
11.647.862.50
54.50
0.55
5.54
7.931.593.67
24.419.93
324.80
0.48
70.00
0.01
-------
Apprndii J
'•-BHa.MBB*BUBIB M* •**••**) UBa,B, O^**fW* BIUBWI/*a,U B*, VW
Title
Diipenion Factor
Annual Throughput
Number of Dayi Opemed. 1988
Dairy Throughput
Percent Volatile Solid*
Reporled/CakulaKd PJ «M»IH Solid*
Reportcd/AatuBcd Peraul Motoure Coato*
Wo Feed
Moimire Fraction
A4 Solid* Fraction
Hot Value of Combunible*
Tola) Air Fraction Sludge Comburilon
Coding Air Waited
Deiired Outlet Temp
Radiation Low Fraction
Solid* (Dry Feed Rale)
Combunible Intel
Dry Gai From Sludge
Moloure from Sludge Combuttlon
Stoichlometiic CombuMlon Air
Tcul Air. Sludge Combuitioo
Moioure Produced Without Fuel Oil
HeatLouc*
ladnenur Outlet WUhout Fuel Oil
Dry Oej Fbu Eiceu Alr
Incinerator Outlet WUhout Fuel Oil
Enthalpy. Dry OM at lada. Outlet
Enthalpy. Uoburc • beta. Outlet
Fuel Oil Required
Max. AlkMable Coacentratkio ofTHC in Catalan*
Diajenloa Factor
laiilaMB r*A*nhuiTft(B) flai Flow Raui
Maximum Sn>ag» Sludge ComhuBioc Oai Flow Ra
Annual Avenge Dally Sludge Feed Rale
Annual Average Volatile Solid* Fraction
Annual Avenge Heat Value of Volatile*
Pud Combuttkia Oat Flow Rale
Average Annual Daily Fuel Uiage Rttt
FuelCoajtaol
Ritk Spedftc Concentration
Body Weight .
Cancer Potency
Inhalation rale
""••••••ln™ munf •<••!
23-20-157
Fall River
1.26
4.288.00
306.00
14.01
78.00
22.00
78.00
5.307.98
0.78
0.22
10.000.00
2.50
0.00
900.00
0.05
1.167.76
9.108.496.73
6.125.91
517.36
6.432.42
16.081.05
4.818.40
644.808.85
8.463.687.88
16.474.54
591.63
212.00
1.460.00
20.17
100.00
1.26
4,908,786.17
3,860.985.44
12.74
0.78
5.54
1.047.800.73
3.225.99
324.80
0.19
70.00
0.01
20.00
• av^vvw ana MCV A^ *»«n
23-20-172
Fitchburg
6.92
2,080.00
130.00
16.00
67.00
25.00
75.00
5.33333
0.75
0.33
10.000.00
2.50
0.00
900.00
0.05
1,333.33
8.933^33.33
6.694.64
507.41
6.308.72
15.771.80
4.665.13
656.853.13
8.276.480.21
16.157.72
600.00
212.00
1.460.00
19.34
100.00
6.92
4,781,872.46
3.786.735.72
14.55
0.67
5.54
995.136.74
3.063.84
324.80
1.02
70.00
0.01
20.00
mrnjfm t**wff t**uu«
23-21-181
Baltimore
0.76
13.394.00
730.00
55.04
75.00
24.00
76.00
19.112.81
0.76
0.25
10.000.00
2.50
0.00
900.00
0.05
4.587.07
34,403.052.49
25.781.65
1,954.09
24.295.44
60.738.59
17.087.21
2.458396.83
31,944,655.65
62.224.80
649.44
212.00
1.460.00
61.13
100.00
0.76
17,727,979.05
14.583.052.37
50.04
0.75
5.54
3,144.926.68
9.682.66
324.80
0.42
70.00
0.01
20.00
23-23-209
Pan Huron
Fluidittd Bed loan.
23.80
641.00
84.00
7.63
70.00
18.00
82.00
3.532.85
0.82
0.30
10.000.00
1.50
0.00
1.400.00
0.05
635.91
4.451.388.89
3.335.87
252.84
3.143.57
4.715.36
3.196.93
293.109.00
4.158.279.89
4.907.66
360.89
342.00
1.710.00
36.17
100.00
23.80
3,747.666.81
1.886.891.79
6.94
0.70
5.54
1.860.775.02
5.728.99
324.80
2.75
70.00
0.01
20.00
VOMTBJJ VB MM »9W Wi
23-23-210
Ann Arbor
1.26
4.853.00
333.00
14.57
50.00
34.00
66.00
3,571.95
0.66
0.50
10,000.00
2.50
0.00
900.00
0.05
1,214.46
6,072322.32
4^50.60
344.91
4.288.27
10,720.69
2.809.60
486346.95
5.S8S.77S.37
10.983.01
701.74
212.00
1.460.00
8.34
100.00
1.26
3,002,821.73
2,573.986.55
13.25
0.50
5.54
428.835.17
1.320.31
324.80
0.12
70.00
0.01
20.00
9OO
23-23-214
Wyandotle
2.66
14.960.00
766.00
78.12
58.00
17.00
83.00
38,294.50
0.83
0.42
10,000.00
2.50
0.00
900.00
0.05
6,510.07
37,758.377.88
28.296.13
2.144.68
26.664.97
66.662.42
34.595.74
2.889.993.89
34.868.383.99
68.293.58
40.77
212.00
1.460.00
297.23
100.00
2.66
31.297382.73
16.005335.64
71.02
0.58
5.54
15,292,047.09
47.081.43
324.80
2.57
70.00
0.01
20.00
23-28-244
Rocky Mount
8.86
2.500.00
365.00
6.85
75.00
30.00
70.00
1.902.59
0.70
0.25
10.000.00
2.50
0.00
900.00
0.05
570.78
4.280.821.92
3.208.05
243.15
3.023.12
7.557.79
1.650.54
305.901.90
3.974.920.02
7.742.72
873.11
212.00
1.460.00
0.75
100.00
8.86
1.853,341.62
1.814.590.44
6.23
0.75
5.54
38.751.18
119.31
324.80
0.51
70.00
0.01
20.00
23-35-287
Hilton
3.27
4.600.00
200.00
23.00
77.00
)i on
4I.W
79.00
9.126.98
0.79
0.23
10.000.00
2.50
0.00
900.00
0.05
1.916.67
14.758.333.33
11.059.89
838.27
10.422.33
26.055.84
8.309.15
1,047.966.62
13.710.366.71
26.693.40
532.26
212.00
1.460.00
40.26
100.00
3.27
8,327,339.04
6,255,885.23
20.91
0.77
5.54
2.071.453.81
6.377.63
324.80
0.84
70.00
0.01
20.00
Riil Ixvel
6.S5E-07
3.50E-06
1.43E-06
9.44E-06
4.00E-07
88IE-06
I.74E-06
2.88E-06
-------
Apprndii J
Calcubiloiu to Derive Sue-Specific RUk-SpecuV Conctnlnuloiu and Kiik IxveU al the 23 Sewage Sludge Incinerator! In Uw Analytical Survey at Hit I MM NSSS
Tilfc
Diipenion Factor
Annual Throughput
Number of Dayi Operated. 1988
Daily Throughput
rtroent Volatile Soiidi
ftrptinrdif^lnilatod ffcrofnl SoUdi
Reported/ AMU ned Percent Uataw Coateat
Wo Red
MoiKure Fraction
Aib Solidt Fraction
Htm Value of Coobuitiblet
Total Air Fraction Sludge Combustion
Coolie* Air Waned
Dnlmd Outlet Temp
11^1)^1^-, LO,, Fncuon
Solid. (Dry Feed Ratt)
Corabuttible Inlet
Dor On From Sludge
Moiuuic from Sludge Combustion
Sioicfaiometric CombUiUon Air
Toul Air. Sludge Combuttioa
MoiHuie Produced WUboul Fuel Oil
HeatLoue*
Incineraior Outlet WUnout Fuel Oil
Dry Go Phil Execu Air
Incinerator Outlet WUftoul Fuel Oil
Enthalpy. Dry Oa> at lado. Outlet
Enthalpy. Molnure * beta. Outlet
Fuel Oil Required
Diajenioa Facur
Mnlauioi Combutflon Gat Flow •••«
Annual Average Dally Sludge Feed Rate
Auual Avenge VotaUk Solidi Fraction
Aaaual Avcnp Heal Vatae of Vohtilu
Fuel Coabualon Oat Flow RMe
Avemje Annual Daily Fuel Ua«e SMC
Fuel Coutaoi
Riik Spedflc Conocmnuoo
Body Weight
Cuou Potency
InhtlaliOQ me
Kiik Uvcl
=========================
23-16-} 14
Euclid
31.20
3.647.00
330.00
11.05
60.00
3600
74.00
3442.15
0.74
0.40
10,000.00
2 SO
0.00
900.00
0.05
920.96
5.525.757.58
4.141.00
313.86
3.902.29
9.755.73
3.032.61
418.808.31
5.106.949.27
9.994.44
550.17
212.00
1.460.00
14.21
10000
31.20
3.073.146.31
2 342 304 14
10.05
060
5.54
730.842.18
2.250.13
324.80
2.96
70.00
001
20.00
1.0 IE-OS
=========
2J-47-+47
Virginia Beach
2.79
7.473.00
377.00
39.10
81.00
2000
80.00
16.291 .68
0.80
0.19
10.000.00
2 SO
0.00
900.00
0.05
3.2S8.34
26J92.528.02
19.778.56
1.499.10
18.638.40
46.596.01
14.998.40
1.852.088.60
24,540.439.42
47.736.17
524.46
212.00
1.460.00
73.79
10000
2.79
14,983,784.98
1 1 187 484 U
35.55
0.81
5.54
3.796.300.42
11.688.12
324.80
1.29
70.00
0.01
20.00
4.42E-06
======^===
33-13-084
Dubuque
Fluidittd Bed Incin.
26.38
3.072.00
225.00
27.48
65.00
3000
70.00
7.632.17
0.70
0.35
10,000.00
1 50
0.00
1.400.00
0.05
2.289.65
14.882.728.49
11,153.12
845.34
10^10.18
15.765.27
6.345.51
1.001.238.68
13.881.489.81
16.408.21
1.053.05
342.00
1.710.00
31.2$
10000
26.58
7,916,492.55
6,308 614 89
24.98
0.65
554
1.607.877.66
4.950.36
324.80
6.49
70.00
001
20.00
2.23E-05
==========
33-39-353
Allegheny
3.41
860.00
218.00
3.94
70.00
1600
84.00
2.054.66
0.84
0.30
10,000.00
250
0.00
900.00
O.OS
328.7$
2,301.213.24
1.724.54
130.71
1.625.12
4.062.81
1.897.26
167.291.52
2.133,931.73
4.162.22
152.29
211.00
1.460.00
14.98
10000
3.41
1.746,395.33
975 461 67
3.59
0.70
5.54
770.933.66
2.373.56
324.80
0.18
70.00
0.01
20.00
6.30E47
==========
35-07-038
Rocky Hill
OfTlile Incinerator
0.83
14,690.00
571.00
77.16
78.00
1800
82.00
35.723.68
0.82
0.22
10.000.00
2 50
0.00
900.00
0.05
6.430.26
50.156.048.91
37.586.94
2.848.86
35,420.20
88450.50
33.027.79
3450,647.85
46,605,401.06
90.717.25
380.12
212.00
1.460.00
205.73
10000
0.83
31,844,915.33
21 260463 67
70.15
0.78
5.54
10,584.351.66
32,587.29
324.80
0.82
70.00
0.01
20.00
2.81 E-06
==========
35-19-149
Nmchiotchet
Fluidiicd Bed IOCJD.
8.80
NA
NA
13.09
75.00
75.00
4.363.33
0.75
0.25
10,000.00
1 50
0.00
1.400.00
0.05
1.090.83
8.181.250.00
6,131.03
464.70
5.777.60
8.666.40
3.823.86
528.578.65
7,652,671.35
9.019.83
937.03
342.00
1,710.00
23.87
10000
8.80
4.695,776.43
3 467 936 38
11,90
0.75
5.54
1.227.840.05
3.780.30
324.80
1.28
70.00
0.01
20.00
4.37E-O6
==========
35-20-164
Billerica
OrTiile locinenaor
NA
NA
NA
0.00
0.00
1.00
10.000.00
? (n
0.00
900.00
0.05
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
ERE
212.00
1,460.00
0.00
0.00
0.00
000
0.00
0.00
5.54
0.00
0.00
324.80
0.00
70.00
0.01
20.00
NA
==========
45-32-274
Oxford
OfTiile Incinerator
3.30
NA
NA
NA
0.00
0.00
1.00
10.000.00
0.00
900.00
0.05
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
ERR
212.00
1.460.00
0.00
3.30
000
0.00
0.00
5.54
0.00
0.00
324.80
0.00
70.00
0.01
20,00
NA
=========
-------
APPENDIX K
WEIGHTED CANCER POTENCY RISK FACTOR FOR THC
-------
WEIGHTED CANCER POTENCY RISK FACTOR FOR THC
Compounds
Carcinogens
Acryl amide
Acrylonitrile
Aldrin
Aniline
Benzene
Benzidine
Benzo[ajpyrene
Bis(2-chloroethyl) ether
Bis(chloronethyl) ether
Bis(2-ethylhexyl) phthalate
1,3-Butadiene
Carbon tetrachloride
Chlordane
Chlorofom
Chloromethane
Chloromethyl methyl ether
000
DOE
Q*
(day-kg/mg)
2.4E-0.1
1.8E-01
1.8E+0.1
2.5E-02
2.9E-02
2.3E+02
1.2E+01
1.2E+00
2.2E+02
8.4E-04
9.7E-01
1.3E-01
1.3E+00
8.1E-02
1.2E-02
9.5E+00
2.4E-01
3.4E-01
95% Emission
concentration
(ng/l)or
0. 1 detection limit
0.1
341,050.9
0.1
0.1
427,500.0
0.1
17.49
0.1
0.1
27,500.0
0.1
139.6
0.1
6,260.5
450
0.1
0.1
0.1
Weight
fraction
1.8E-06
1.8E-02
1.8E-06
1.8E-06
5.5E-03
1.8E-06
3.1E-04
1.8E-06
1.8E-06
8.3E-04
1.8E-06
3.3E-05
H8E-06
3.8E 03
8.0E-03
1.8E-06
1.8E-06
1.8E-06
Weighted Q*
(day-kg/mg)
4.3E-07
3.2E-03
3.1E-05
4.4E-08
1.6E-04
4.1E-04
3.6E-03
2.1E-06
3.9E-04
7.0E-07
1.7E-06
4.3E-06
2.3E-06
3.1E-04
9.3E-05
1.7E-05
4.3E-07
6.0E-07
Source: U.S. EPA, 1991k.
(continued)
-------
Appendix K (continued)
Compounds
Carcinogens (continued)
DOT
l,2-Dibromo-3-chloropropane
1,2-Dibronoethane
1,2-Dichloroethane
1,1-Dichloroethylene
Oieldrln
Oiethylstllbestrol
Oioxane
1,2-Diphenylhydrazine
Epichlorohydrin
Ethyl ene oxide
Formaldehyde
Heptachlor
Heptachlor epoxlde
2,3,7,8-Heptachlorodibenzo-p.-dioxin
other-Heptach1orodibenzo-j)-dioxin
Hexachl orobut ad 1 ene
« - Hexach 1 orocyc 1 ohexane
Q*
(day-kg/rog)
3.4E-01
2.2Et01
7.8E-01
9.1E-02
1.2E+00
1.6E+01
4.9E+02
4.9E-03
8.0E-01
4.2E-03
3.5E-01
4.4E-02
4.5E+00
9.1E+00
1.8E+02
1.8E+00
7.8E-02
6.3E+00
95% Emission
concentration
(ng/l)or
0.1 detection limit
0.1
0.1
0.1
61.18
1.03
345.65
0.1
0.1
0.1
0.1
0.1
780
0.1
0.1
0.00049
0.14
0.1
0.1
Weight
fraction
1.8E-06
1.8E^06
1.8E-06
2.3E-05
1.8E-05
1.8E-06
1.8E-06
1.8E-06
1.8E-06
1.8E 06
1.8E-06
1.4E-02
1.&E-06
1.8E-06
9.2E-09
LIE 08
1.8E-06
1.8E-06
Weighted Q*
(day-kg/rog)
6.0E-07
3.9E-05
1.4E-06
2.0E-06
2.1E-05
2.8E-05
8.7E-04
8.7E-09
1.4E-06
7.5E-09
6.2E-07
6.0E-04
8.1E-06
1.6E-05
1.6E-06
1.9E-OS
1.4E-07
1. IE-OS
(continued)
-------
Appendix K (continued)
Compounds
Carcinogens (continued)
beta-Hexachlorocyclohexane
gaona-Hexachlorocyclohexane
Hexachlorocyclohexane, technical
2,3,7,8-Hexachlorodibenzo-p.-dioxin
other-Hexachlorodibenzo-g-dioxin
Hexachloroethane
3 -Methyl chol anthrene
Nethylene chloride
4,4-Methy1ene-b1s-2-chloroaniline
Methyl hydrazine
2-Nitropropane
tj-Nitrosodi-o-butylamine
fl-Ni trosodi -fl-propyl anine
M-NUrosodiethylaalne
Ij-Nitrosodimethyl anine
H-Nitrosopyrrolidine
PCBs
2,3,7,8-Pentachlorodibenzo-g-dioxin
Q*
(day-kg/mg)
1.8E+00
1.3E-01
l.BEfOO
6.2E+03
7.0E+01
1.4E-02
9.5E+00
1.5E-02
1.7E-01
1.2EtOO
2.0E+02
5.6E+00
7.0E+00
1.5E+02
4.9E+01
2.2E-00
7.0EfOO
8.8E+04
95% Emission
concentration
(ng/l) or
0.1 detection limit
0.1
0.1
0.1
0.00048
0.062
0.77
0.1
11,495
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.00013
Weight
fraction
1.8E-06
1.8E-06
1.8E-06
9.0E-09
3.9E-08
1.4E-05
1.8E-06
1.5E-03
1.8E-06
1.8E-06
1.8E-06
1.8E-06
1,8E-06
1.8E-06
1.8E-06
1.8E-06
3.5E-06
2.5E-09
Weighted Q*
(day-kg/mg)
3.3E-06
2.3E-07
3.1E-06
5.6E-05
2.7E-06
1.9E-07
1.7E-05
2.2E-05
3.0E-07
2.1E-06
3.5E-04
9.8E-06
1.3E-05
2.7E-04
8.7E-05
3.9E-06
2.5E-05
2.2E-04
(continued)
-------
Appendix K (continued)
Compounds
Carcinogens (continued)
other-Pentachlorodibenzo-g-dioxin
Pentachloroni trobenzene
Pronamide
Reserpine
2,3, 7 ,8-Tetrachl orod i benzof uran
2,3,7,8-Tetrachlorodibenzo fi-dioxin
other-Tetrachlorodibenzo-g-dioxin
1,1,2,2-Tetrachloroethane
Tetrachloroethylene
Thiourea
Toxaphene
1,1,2-Trichloroethane
Trichloroethylene
2,4,6-Trichlorophenol
Noncarcinogens
Acetonitrile
Acetophenone
Q*
(day-kg/rog)
8.8E+02
2.5E-02
1.6E-02
1.1E+01
1.8E>04
1.8Ef05
1.8E+03
2.1E-01
1.7t-03
1.9E+00
1.1E+00
5.76-02
1.3E-02
2.0E-02
O.OE+00
O.OE+00
95% Emission
concentration
(ng/qor
0.1 detection limit
0.0032
0.1
0.1
0.1
0.00370
0.000076
0.0072
0.1
228.77
0.1
0.1
o.i
120.21
0.1
281.2
0.1
Weight
fraction
6.0E-08
1.8E-06
1.8E-06
l.BE-06
6.6E-08
1.4E-09
1.3E-07
1.8E-06
4.1E-03
1.8E-06
1.8E-06
1.8E-06
2.1E-03
I.8E-06
5.3E-03
1.8E-06
Weighted Q*
(day-kg/mg)
5.3E-05
4.4E-08
2. BE -08
1.9E-05
1.1E-03
2.5E-04
2.3E-04
3.6E-07
6.8E-06
3.4E-06
2.0E-06
l.OE-07
2.8E-05
3.5E-08
0
0
{continued)
-------
Appendix K (continued)
in
Compounds
Noncarcinogens (continued)
Allyl alcohol
Brorood i ch 1 oromet hane
Bromoforn
Bromomethane
2-Chloro-l,3-butadiene
Cresols
Di-fi-butyl phthalate
Oibrofflochloronethane
Dichlorodifluoronethane
2,4-Dichlorophenol
1,3-Dichloropropene
01 ethyl phthalate
Dimethoate
2,4-Olnitrophenol
Diphenylamine
Endosul fan
Endrin
Ethyl benzene
Q*
(day-kg/mg)
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
95% Emission
concentration
(ng/L) or
0.1 detection limit
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
40.03
0.1
0.1
0.1
260.95
0.1
0.1
0.1
95.0
Weight
fraction
1.8E-06
1.8E-06
1.8E-06
1.8E-06
1.8E-06
1.8E-06
1.8E-06
1.8E-06
1.8E-06
7.1E-04
1.8E-06
1.8E-06
1.8E-06
4.6E-03
1.8E-06
1.8E-06
1.8E-06
8.6E-04
Weighted Q*
(day-kg/mg)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(continued)
-------
Appendix K (continued)
Compounds
Noncarcinogens (continued)
Formic acid
Hexachl orocyc 1 opentad i ene
Hydrogen cyanamide
Isobutyl alcohol
Isophorone
Me thorny]
Methoxychlor
Methyl ethyl ketone
Methyl parathion
Nitrobenzene
Pentachl orobenzene
Pentachlorophenol
Phenol
N-Phenylenediamine
Phenylmurcuric acetate
Pyridine
Selenourea
Strychnine
Q*
(day-kg/mg)
O.OEtOO
O.OEtOO
O.OEtOO
O.OEtOO
O.OEtOO
O.OEtOO
O.OEtOO
O.OEtOO
O.OEtOO
O.OEtOO
O.OEtOO
O.OEtOO
O.OEtOO
O.OEtOO
O.OEtOO
O.OEtOO
O.OEtOO
O.OEtOO
95% Emission
concentration
(ng/L)or
0.1 detection limit
0.1
0.1
0.1
0.1
0.1
0.1
0.1
165.3
0.1
3.17
0.1
77.37
8,388.5
0.1
0.1
0.1
0.1
0.1
Weight
fraction Weighted Q*
(day-kg/rog)
1.8E-06
1.8E-06
1.8E 06 .
l.BE-06
1.8E-06
1.8E-06
1.8E-06
3.1E-03
1.8E-06
5.6E-05
1.8E-06
1.4E 03
2.1E-03
1.8E-06
1.8E-06
1.8E-06
1.8E-06
1.8E-06
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
(continued)
-------
Appendix K (continued)
Compounds
Noncarclnogens (continued)
1,2,4,5-Tetrachlorobenzene
2,3,4,6-Tetrachlorophenol
Tetraethy) lead
Toluene
1 ,2,4-Trichlorobenzene
1,1,1-Trichloroethane
Trichlorofluoromethane
2,4,5-Trichlorophenol
C, Hydrocarbons
C, Hydrocarbons
Q*
(day-kg/mg)
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
O.OE+00
95% Emission
concentration
(ng/l) or
0.1 detection limit
0.1
0.1
0.1
215.02
332.5
11,115.0
0.1
0.1
17,575
34,200
Weight
fraction
1.8E-06
1.8E-06
1.8E-06
3.8E-03
5.3E-04
1.7E-03
1.8E-06
1.8E-06
3.1E-01
6.1E-01
Weighted Q*
(day-kg/mg)
0
0
0
0
0
0
0
0
0
0
TOTAL
,645.43
1.2E-02
-------
APPENDIX L
EMISSIONS DATA FOR ORGANIC COMPOUNDS USED TO DERIVE q,« FOR THC
-------
Uiuik
3lt»1
T«
2.71 6-a
7.ioe«oi
4.M6>03
2.40£<00
t.20E«00
1.20E*00
2.40E«00
I.10E<01
>.37C<01
Sit. 2
om th« control
outtot)
Si I* 3
SIU4
(Valun from »• con not
d«vK» oudti)
SIMS
SIM*
(VifeM* tram Hi* oontrol
dtvio* ouMl)
SIM»
(VtkiM from ttw control
dtvic* ouMI)
SIM 10
1
2
3
4
«
a'
Avtrtg*:
t
2
3
J.8M-01
8.ME-01
«.«OE-41
8.40E-01
3.22E-01
8.30€-01
8.44E-01
1.90EWW
3.20E-03
noe-oa
2.20C-02
2.1IE-09
2.10C-02
1.90E«O1
4.«OC*01
t.MC<«0
t
2
3
4
S
6
AlMflOK
1
2
3
Average:
i
2
3
Avcrigt
t
2
3
Average
1
2
3
4
S
4.07E*Oa
3.33E<«3
1.M6<09
i.ose««a
UTOCtOO
3.20E-02
3.20E-M
110E-03
3.10E-02
3.17E«00
2.SOE-01
iao€-oi
«.ooc-oi
4.37E-01
2.8M-01
•.7oe-oi
e-oa
aoE-oa
90C-02
.aoe-oa
4.S4E«01
7.43£«0t
8.02E*00 4.038*00
2.20E*09
1.10E«00
X74C-01
3.01 e-oi
7.5TE-01
3.00E-01
3.00E-01
t.73E<«1
2.74C<«1
Xt«K«O1
3.44C«O1
2,72C«O1
3.71E2
2.9
2,1lE««e
1.47E«09
Source: U.S. EPA, 1991k.
L-l
-------
1.2-
Slit 1
(Valun from m« control
device outlet)
Sill 3
Site 4
(Value* trom the control
device outlet)
311*5
St*t
(Valu** Iram Oi* control
devise outlet)
Site 9
(Value* from me control
device outlet)
Sit* 10
Teetfeo.
i
2
}
4
5
Average
t
2
3
Average:
1
2
3
Average:
1
2
3
4
s
Av«r*gK
1
2
3
An ir age1
1
2
3
Average
1
2
3
t.90641
1.00641
1.90641
1306-01
1.90640
4. (2641
Oilonse
2.8*641
4.88641
7.07E41
5.56641
1.52641
4.30641
'91E-M
7.54641
1.09642
8.04641
8.90641
1.54642
TrteMorc
etftene
i.43£«01
CM
Bk>(2-€aiyl
«««yf)p«
'•2-aotiora
7.M6.00
t.40642
1.07E41
1.03E««3
3.20E-03
3.20E-42
3.20E-02
3.20E-02
itoE-oa
3.10E-02
S.40E-02
S.30E-02
5.406-02 *
s-006-oa
5.106-03
S.20E-03
.90E-01
.aoE-01
.aoe-oi
.006-01
.506-01
.SOE-01
.10E-01
.106-01
.106-01
.106-01
.006-41
.006-01
1.906-01
1.90E-01
t.aoE-oi
i.aoE-oi
i.soE-ai
1.ME-01
4.M6-01
4.WE-01
4.906-01
4.M6-01
4.906-01
4.706-01
X17EWX)
3.006-01
1106-01
3.206-01
3.106-4)1
S.406-02
S.M6«00
S.M6<00
1.406*00
4.07E«00
I.STE-01
2.706-01
2.806-01
3.05E«00
1.076-01
1.106*00
2.00E.OO
I.40E<00
3.06«00
1.576-01
1006-01
3.006-01
9.006-01
S.006-01
4.776-01
S.M6-01
s.aoe-oi
9.306-01
«K
•.00641
«.I9E W31
3.81 E«01
1. 916.O2
3.S46<01
3.S4E«Ot
1.SOE<01
7.20640
7.306«00
4.««6«01
S.20640
3.0«6<01
i.ai6«oi
1.536*01
3.90641
4.34641
2.93E4I
3.23641
3.40641
1.ME41
154641
1.36641
3.54641
2.5*641
2.6*641
1.11640
1.07640
1.07640
1.09640
0.00640
0.00640
0.00640
3.19640
1.12640
1.57640
1.49642
1.8SE42
1.10642
4.SIE41
1.29641
2.89641
1.03642
•.50641
1.00642
$.0*641
4.14641
9.02641
5.51842
1.97642
4.7*642 '
4.95641
1.99641
•J5641
1.7W42
1.5*642
1.23642
1.03643
7.42641
1 .29643
8.7*641
1.03641
L26V42
0.00640
0.00640
0.00640
1.03640
1.30640
1.20640
1.S0640
1.33640
S.M642
0.00640
0.00640
0.00640
0^0640
0.00640
0.00640
040640
•v«4641
STTE AVERAO6 - MAX
SITe AVEBAOE - 96TM
• Oeteeflon Umtn
" Reponed a* iifl/aeem.
Oarina/ruran irere reported In ngMaem
and ccnvernd to "9/1
0.44641
0.12641
4.82E41
2.30641
2.S0641
2.70641
2.50641
1.44642
4.4SE41
1.35E42
1.0SE42
8.42641
1.11641
1.47641
183641
2.44C44
7.29649
5.90643
103644
5.30643
2.04644
0.00640
2.28644
2J4649
1.21644
S.406-02
1^1644
1.18644
7.40641
1.27642
WT641
5J0640
1.98641
•.40640
0.40640
2.10641
3.3*641
X21641
2.90641
1.44C4*
4.67649
0.00640
4.14640
1.4*641
19*640
5.94649
3.72649
1.67649
•.71640
7.34640
U4649
£24641
2.7S641
2.39641
2.40641
040640
1^3642
5J7E41
727644
(.00649
2.30644
0.00640
2.93644
S.7S644
1.52644
1.57641
1.52644
1.44644
7.4*644
6\2Ct44
1.11649
V40649
6\00649
1.«764«
1.07641
1.17644
1.77649
1476-01
7.89640
1.03641
121640
7.09640
2.92641
1.48641
3.72649
8.40644
1.04649
9.70642
1.24644
2.15644
1.97644
172E44
1.11649
2.90644
7.0*640
2.90644
Z78644
8.15640
2.05640
^56641
1.2*641
0.00640
5.34649
(.40642
1.40642
1.14644
0.00640
1.83644
1.14644
9.78649
8.14649
1.0*640
8.14649
5.M649
L-2
-------
Ugnloo* Shida* Indnaraten
Sli* 1
i
Sin 2
(ValuM from tn* control
diviot outl«i)
SIM1
Sit* 4
(Valun from tfi* control
diviot ouitot)
Si 1*5
Sit««
(VtluM tram m« control
d*vio» ouO*i)
siwa
(VDuM tram th* control
d*viot ouO*l)
SIM 10
SITE AVERAGE -UIN
STTE AVERAGE -MAX
STTE AVERAGE - 9STH
TMINO.
1
2
1
4
t
Average
i
2
3
4
5
a
Avcraoi:
1
2
3
Av.r.0*
1
2
3
4
M.
1
2
3
Av*r*gc
1
2
3
Avwag*
1
2
3
Av*ng>
1
2
3
4
•
7
1
*
t,40loMaro
awinn*
8.77E.01
2.116*01 •
7.226*01
1.286*02
7.17E*01 '
S.07&01
2.47E*91
4.17E«01
I.ME*OI
2.97E*01
3.63E.01
X336.01
1.116*00 *
t.07E*00 '
1.07E«00 '
1.0»E*00 •
1.MC«01
X016*01
1.1«C*01
zoae«oi
XOIS*01
1.841*01
3^0C*02
1J*<*0«
4^1C*00
2.MC*0(
1.1tC*M
A M^K^J^
0-BDV4OT
1.71 1*0*
1.MC*M
1^UC«0«
*^M8*OB
i.o«*a>
LWK*0«
».41C*OB
i._aowor« 2.4-Onwo P^nlM^ur, »—<.( ,
•tMnol pM«ol PIMM DAM,* (^^ e
i.o0E«oi • zaae*oi • i.7ZE*o2 • S.HE«OI • i.i«e
1JOC«O9
7.t7e*fl>
2.70C«09
l!a7i*M
1.»1E»0*
t.9(C*04
* &^B-Mt
»J3K*wB
1.0M*Oa LTOE^O X11t*01 •J0t*00 1JDC*0«
(.(M*09 4^1E*01 2.79K*OI (.11«*01 14«C*01
(.3M«0» 4.00f*01 X01C*03 7.741*01 I.TtC^I
2.4-Trt
htoroMnan* AWrto
1.9»E«S1 ' 1.1S€^2
2.29E«31 • 1.33E.03
4.94E<01 * 2.87t-J2
X33E«01 • 1.M€rf3
X14E*01 * 1.«2E*02
2.40E«00 • Z40E«00
t.30E«00 * .70E«OO
I.IOEtOO * .«OE«00
1.10E*00 • .«OE«00
1.10E«00 • .60E*00
1.20E-00 • .SOE*00
1.37E«00 * t.«E«00
1.07E«00 * 2.2E*OO
t.aoE*00 * 2.14E.OO
1.aOE«OO • 2.13E«CO
1.82E«00 * 2.18E«OO
a.9«c*o>
x»€^a
*
1.37E*00 t.a»E*00
xioc*oa i.«ae*«2
X3oc«oa i.7ae«oa
• OtMcdon LlmHi
•• RtoertM • uoVdtenv
(XodM/furan ••»• '»pon*d In no/d*om
L-3
-------
Sl»t
T«t No.
Olontw*
OMtfrvt
1.046*33 •
0.006*00
1.206*03 •
2.S0E»03 *
1.756*02 •
2371 TCOO
Om«r
TCOO
237S iH^M>
OOMf
PCOO
2S71 HiCOO
1.326.02 •
Sit. 2
(Valut* Irom HI* control
dcvie* ouMt)
2.566*01
1.606*00 * 2.726*03
2.606*00 * 1.8*6*03
2.306*00 * 1.726*03
2.326*91 * 2,306*90 • 1.766*03
2.296*91 • 2.306*00 * 1.746*03
2.296*91 • 2,306*00 ' 1.746*03
Sit* »
(Valun tram m« oenirel
7.8
7.S4C-OB
7.H
0.001*30
S.OH-0*
Olodnt/lunn «*ra r*pen«d In nylitam
and cenvwiM to ng/L
L-4
-------
TMINO.
Hraenloro
SiM I
Sin 2
(ValuM Irom m« oontrol
dtvic* outtot)
Sit* 3
Sin*
(Valgn Iron in* control
dtvio* outt*i)
Avar 104:
I
2
3
1.116*01 3.306*00
1346*01 6.206*00
»9*6*01 6.306*00
1.336*01 9.106*00
2.436*01 2.506*00
3.246*01 5.546*00
1.606-01 3.706-42
1.606-01 3.706-02
1.606-41 3.506-03
1.606-01 3.706-03
1.506-01 3.606-03
1.506-01 3.606-03
1.576-01 3.6*6-03
3.006-01 2.006*00
1906-01 * 1106*00
2.506*00 l*06«oa
1.036*00
1.848-03
1.S3E-03
1.44C-03
7.20H-04
4.306-04 4,»0e-04
S.30E-04 S.M6-0*
4.606-04 4.M&04
1.406-04 2.106-04
T. 906-04 i. 046-49
7.106-04 S.006-04
2.24C-49
S. 176-04
s.aw-04
4.146-08
4.436-93
4.476-09 2.S36«01
1.236-09 t.M6*M
4^06-09 4.336-01
3.67E-09 1.a06«00
«.ioe«oi
SIM*
(Vdum (ram DM oontrol
d«vio» outer)
at* 9
(ValUM (rom tfi» oontrol
dtvioi oud«l)
1
2
3
Avwagc
1
2
3
Av«f«g»
1
2
3
61506*00
•.706*00
7.606*00
7.606*00 6.006*00
8.376*01
i.aae*03
1.136*02
7.aof*oi
7.306*01
1.256*02
1.026*02
8.506*00 8.006-01
5.706*09 9.006-01
a.MC*oo *.ooc-oi
7.706-01
X17C*OB
9.906-0*
9.436-0*
0.006*00
3.5*6-0*
1.306-01
0.006*09
0.006*00
8.S06-03
6.976-0*
0.006*09
0.006*00 1.<
4.926-0*
2.336-0*
1.M6-0*
2.506-01 1.306*00
5.006-02 2.506-01
0.006*00 0.006*00
1.:
1.296*00 6.7*6*00
4.406*01
1226*00 8.
2.0*6*00 6.776*00
1.376*02 £346*01 0.006*00
1.076*02 1226*01 1.436*0*
5.716*01 8.906*00
1.006*02 1.7*6*01
S» 10
I.It
•.006*01
1.0*1*0*
6.736*0*
3.876*0*
1.0*6*0*
0.006*00
1606*04
1.176*0*
STTE AVERAGE - MIN
srrEAVERAoe-MM
STTE AVERAO6 - OCTH
• 0»t»ction Umt»
0.006*00 2.326-0* 1.54C-0*
5.176-04 1.506-01 1.3*6-01
5.176-04 1.406-01 7.906-01
1.576-01
1.006*0*
0.006*00
1.176*0*
1.116*04
0.006*00
3^06*00
Dioxlitt/furan M
•nd oomwttd » ng/l
L-5
-------
cflveeion ri
i.l-Otontor&T . 1.3-OfcHlore-
Uiuiidpit Stodge Mnenuon TeetNe. tiriene propene
an* i i
2
3
4
Site 2 1
(Vakiea (ram the control 2
into* oudet) 3
4
t
9
Avenge:
Slt»3 • t
2
3
SIU4 1
(Valun from »• control 2
dcvie* ouHW) 3
4
S
a
Average
Slt»S 1 1.20E«00
2 7.00E-01
3 1.20E«00 1.00E-01
1.03E*00 4.006-02
Site* 1
-------
APPENDIX M
PERFORMANCE INDICATOR PARAMETERS FOR
AIR POLLUTION CONTROL DEVICES
-------
Appendix M
PERFORMANCE INDICATOR PARAMETERS FOR
AIR POLLUTION CONTROL DEVICES
APC Device
Venturl scrubber
Impingement scrubber
Mist eliminator (types
Include a wet cyclone* vane
demlster, chevron demlster,
mesh pad, etc.)
Dry scrubber
(spray dryer absorber)
Parameter
Pressure drop
Liquid flow rate
Gas temperature
(Inlet and/or
outlet)
Gas flow rate
Pressure drop
Liquid flow rate
Gas temperature
(Inlet and/or
outlet)
Gas flow rate
Pressure drop
Liquid flow
Liquid/reagent
flow rate to
atomizer
pH of liquid/
reagent to
atomizer
For rotary
atomizer:
Atomizer motor
power
(continued)
Example Measuring Devices
Differential pressure (A?)
gauge/transmitter
Orifice plate with AP
gauge/transmitter
Thermocouple/transmitter
Annubar or Induced fan (ID)
parameters
AP gauge/transmitter
Orifice plate with AP gauge/
transmitter
Thermocouple/transm1tter
Annubar or ID fan parameters
Differential pressure gauge/
transmitter
Orifice plate with AP gauge/
transmitter
Magnetic flowmeter
pH meter/transmitter
Wattmeter
Source: MRI, 1990.
M-l
-------
Appendix M (CONCLUDED)
Fabric filter
Wet electrostatic predp-
Uator (ESP)
For dual fluid
flow:
Compressed air
pressure
Compressed
airflow rate
Gas temperature
(Inlet and/or
outlet)
Pressure drop (for
each compartment)
Broken bags
Opacity
Gas temperature
(Inlet and/or
outlet)
Gas flow rate
Secondary voltage
(for each trans-
former/rectifier)
Secondary currents
(for each trans-
former/rectifier)
Liquid flow(s)
(for separate
liquid feeds)
Gas temperature
(Inlet and/or
outlet)
Gas flow rate
Pressure
Or1f1ce plate with
AP gauge/transmitter
Thermocouple/transmitter
A? gauges/transmitters
Proprietary monitors
Transmlssometer
Thermocouple(s)
Annubar or ID fan
parameters
Kilovolt meters/transmitter
Mill 1 ammeters/transmitter
Orifice plate(s) with AP
gauge/transmitter
Thermocouple(s)
Annubar or ID fan .parameters
M-2
-------
APPENDIX N
CALCULATION OF THE AMOUNT OF SEWAGE SLUDGE USED OR DISPOSED
-------
CALCULATION OF THE AMOUNT OF SEWAGE SLUDGE USED OR DISPOSED
FOR THE PART 503 FREQUENCY OF MONITORING REQUIREMENTS
Office of Science and Technology
U.S. Environmental Protection Agency
401 M Street, 8.W.
Washington, D.C. 20460
November 23, 1992
N-l
-------
CALCULATION OF THE AMOUNT OF SEWAGE SLUDGE USED OR DISPOSED
FOR THE PART 503 FREQUENCY OF MONITORING REQUIREMENTS
INTRODUCTION
The Standards for the Use or Disposal of Sewage Sludge in 40
CFR Part 503 contain frequency of monitoring requirements for land
application of sewage sludge, placement of sewage sludge on a
surface disposal site, and firing of sewage sludge in a sewage
sludge incinerator. These requirements indicate how often sewage
sludge has to be monitored for pollutant concentrations, pathogen
densities, and vector attraction reduction. They are based on the
amount of sewage sludge used or disposed during a 365 day period.
For land application, the frequency of monitoring requirements
are based either on the amount of bulk sewage sludge.applied to the
land or the amount of sewage sludge received by a person who
prepares the sewage sludge for sale or give away in a bag or
similar enclosure for application to the land. As those amounts
increase, the frequency of monitoring increases.
For surface disposal and firing of sewage sludge in a sewage
sludge incinerator, the frequency of monitoring requirements are
based on the amount of sewage sludge placed on a surface disposal
site and the amount of sewage sludge fired in a sewage sludge
incinerator, respectively. For these two practices, the frequency
of monitoring also increases as the amount of sewage sludge used
or disposed increases.
This document discusses calculation of the amounts of sewage
sludge used or disposed for the Part 503 frequency of monitoring
requirements. The assumptions on which those requirements are
based and the calculations for the amounts used or disposed are
presented below. Also presented below are the Part 503 frequency
of monitoring requirements.
ASSUMPTIONS
o Wastewater is treated in "typical" secondary wastewater
•treatment plant (i.e., primary settling followed by
biological treatment followed by secondary settling).
o Sewage sludge is stabilized in an anaerobic digester
prior to use or disposal.
o Influent wastewater BODS concentration =» 200 mg/1.
o Effluent wastewater BODS concentration = 30 mg/1.
o Influent wastewater TSS concentration = 200 mg/1.
o Effluent wastewater TSS concentration = 30 mg/1.
N-2
-------
o TSS percent removal in primary treatment process = 60.
o Percent volatile solids in the influent to digester =60.
o Percent volatile solids reduction in digester = 38.
o Percent fixed solids in the influent to digester =40
o Solids concentration factor during
secondary settling = 0.9
CALCULATIONS FOR TREATMENT WORKS WITH A FLOW RATE OP ONE MGD
o TSS removal in primary treatment process:
Influent TSS x Flow rate x Conversion factor x Percent removal
200 mg/1 x 1 MGD x 8.34 x 0.6 = 1.000 pounds per day.
o BODS removal through secondary settling process:
Influent BODS - Effluent BODS = 200 - 30 = 170 mg/1
Concentration removed x Flow rate x Conv. fact, x Cone. fact.
170 mg/1 x 1 MGD x 8.34 x 0.9 = 1.276 pounds per day.
o Sewage sludge to the digester:
Primary settling sludge + secondary settling sludge = total
1,000 + 1,276 = 2.276 pounds per day.
o Amount of sewage sludge used or disposed:
Fixed solids = total amount x percent of total solids.
Fixed solids - 2,276 x 0.4 — 910 pounds per dav.
Volatile solids « total amount x percent of total solids x
percent remaining after digestion.
Volatile solids - 2,276 x 0.6 x (1.0 - 0.38) • 847 pounds/day
Total amount used or disposed = Fixed solids + volatile
solids
910 + 847 = 1.757 pounds per day
Total amount » 1,757 pounds x 365 davs x 1 metric ton
days year 2,200 pounds
Total amount for 1 MGD = 292 metric tons per vear.
N-3
-------
Report amount in two significant figures:
Use 290 metric tons per year for 1 MGD treatment works (dry
weight basis)
CALCULATION FOR A TREATMENT WORKS WITH A FLOW RATE OP FIVE MGD
Total amount = Amount for 1 MGD treatment works times 5
Total amount = 290 x 5 = 1.450 metric tons per year
Report amount in two significant figures:
Use 1.500 metric tons oer year for five MGD treatment wcr!
------- |