tJntl&d Slates
Control Technology Center
October IS96 KPA-6QQ 1
S-EPA WOOD PRODUCTS IN 1 HE WASTE
5TREA M— CBAHA CTERIZAT10 N
AND COMBUSTION EMISSIONS
Volume 1. Technical Report
control ^ tech
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Control Technology Center
Sponsored by:
Emission Standards and Engineering Division
Office of Air Quality and Planning and Standards
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
EPA REVIEW NOTICE
This report has been reviewed by the U.S. Environmental Protection Agency and
approved for publication. Approval does not signify or imply that the
contents necessarily reflect the views and policies of the Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
This document is available to the public through the National Technical
Information Service, Springfield, Virginia 223.61.
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E FA - 600/R-96-119 a
October 1996
Wood Products in the Waste Stream - Characterization and Combustion
amissions
Volume 1, Technical Report
By:
Richard S. Atkins
Environmental Risk Limited
120 Mountain Avenue
Bloomfield, CT 06002
and
Christine T. Donovan
C.T. Donovan Associates, Inc.
P.O Box 5655
22 Church Street
Burlington, vt 0 5402
Subcontractors to i
New York State Energy Research and Development Authority
2 Rockefeller Plaza
Albany, NY 12223
EPA Cooperative Agreement CR815271
EPA Project Officer:
Robert C. McCriliis
Air and Energy Engineering Research Laboratory
Research Triangle Park, NC 27711
Prepared for;
U.S. Environmental Protection Agency
Office of Research and Development
Washington, D.C. 20460
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ABSimCI1
Waste wood, an alternative to the combustion of fossil fuels, has raised
concerns that iff it is "contaminated" with paints, resins, preservatives, etc.
it may generate unacceptable environmental impacts during combustion. Given
the difficulty of separating the waste wood and the possible size of the
resource, it is important to identify the problems associated with combustion.
This project is designed to:
• Identify the quantity and quality of waste wood;
• Summarize of regulatory issues affecting the processing and
combustion of waste wood for energy;
• Characterize waste-wood processing and combustion
facilities;
• Characterize representative waste-wood samples; and
• Collect and analyze emission data from operating combustion
facilities.
Waste wood is wood separated from the solid-waste stream and processed
into a uniform-sized product that is reused for other purposes such as
fuel. Specific types of wast© wood described include:
• Pallets;
• Construction and demolition waste;
• Wood treated with paints or stains;
• Wood containing glues, binders, or resins;
• Mood containing plastics or vinyl;
• Wood treated with preservatives such as creosote,
chloropentaphenol and chromium copper arsenate; and
• Wood treated with pesticides or fungicides.
This study, completed in mid-1992, describes research about technical,
public policy, and regulatory issues that affect the processing and
combustion of waste wood for fuel,
The project's purpose was to provide environmental regulators, project
developers, and others with data to make informed decisions on the use
of waste wood materials as a combustion resource. Potential
environmental problems and solutions were identified.
A specific project result was the identification of combustion system
operation parameters and air pollution control technologies that can
minimize emissions of identified air and solid waste contaminants from
combustion of waste wood.
ii
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Table of Contents
Section Ems.
ABSTRACT ii
List of Figures . ix
List of Tables . ........... x
EXECUTIVE SUMMARY ES-l
Defining "Clean" ar.d "Treated" Wood ES-l
Federal, State, and Provincial Regulations ES-l
Types and Amounts of Waste Wood Available for Fuel ..... ES-4
Compos it: ion of Waste Wood ES-5
Waste-Wood Processing Facilities ... ES-6
Waste-Wood Combustion Facilities .............. ES-7
Chemical and Physical Properties of Waste Wood and
its Ashes £5-8
Environmental Impacts of Waste-wood Combustion - Air .... ES-9
ACKNOWLEDGEMENTS ES-11
1.0 INTRODUCTION ..... ............... 1-1
1.1 ftie Defining of "Clean" and "Treated" Mood ....... 1-1
1.2 Research Methodology 1-3
1.3 study Area 1-3
1.4 Organization of the Final Report ..... . 1-3
2.0 ENVIRONMENTAL REGULATIONS ......... . . 2-1
2.1 Introduction ...................... 2-1
2.1.1 Key Issues In Federal hit Quality Regulations . 2-1
2.1.1.1 Key Findings .............. 2-2
2.1.2 Key Issues In State Air Quality Regulations . . 2-2
2.1,2.1 Key Findings. .............. 2-2
2.1.3 Key Federal Solid Waste issues ......... 2-3
2.1.3.1 Key Findings .............. 2-3
2.1.4 Key Issues in state Solid Waste Regulations . . 2-4
2.1.4.1 Key Findings .............. 2-4
2.1.5 Key Energy Policy Issues ............ 2-5
2.1.5.1 Key Findings .............. 2-5
2.2 Federal Air Pollution Regulations ........... 2-5
2.2.1 OSIPA ......... 2-5
2.2.1.1 Mew Source Performance Standards .... 2-6
2.2.1.2 National Emission Standards for Hazardous
Air Pollutants (NESHAPS) ........ 2-6
2.2.1*3 Maximum Achievable control Technology
(MACT) Standards ............ 2-7
2.2.1.4 Prevention of Significant Deterioration
{PSD} Regulations ........... 2-7
2.2.2 Canadian Air Regulations . 2-9
2.3 Comparison of Regulatory Air Emission Requirements Within
The study Area 2-9
2.3.1 State and Provincial Air Regulations ...... 2-9
2.3.2 Applicable Regulations ............. 2-9
2.3.3 Wood Source Considerations ........... 2-11
2.3.4 Criteria Pollutant Emission Standards ..... 2-12
2.3.5 Best Available Control Technology {BACT) .... 2-14
iii
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Table of Contents, continued
Section Page
2.3.6 Nonattainraent Review 2-16
2.3.7 Hazardous Air Pollutants ............ 2-16
2.3.8 Regulatory Climate/Additional Requirements . . . 2-19
2-4 Federal. Solid Waste Regulations . 2-22
2.4.1 USEPA Definitions of Solid and Hazardous Waste . 2-22
2.4.2 Exclusions under RCRA . , . 2-23
2.4.3 Ash Disposal Regulations 2-25
2.4.4 USEPA Solid Waste Regulatory Trends 2-25
2.4.5 Federal Solid Waste Guidelines in Canada .... 2-26
2.5 State/Provincial Solid Waste Regulations ........ 2-2?
2.5.1 Regulatory Definitions of '"Clean* and "Treated*
Haste Wood 2-27
2.5.2 Regulations or Policies on C/D Waste Wood . . .2-29
2.5.3 Is Waste Wood for Fuel Considered Recycling? . . 2-30
2.5.4 Definitions of waste wood Combustion Facilities 2-30
2.5.5 Definitions of Waste Wood Processing Facilities 2-31
2.5.6 Ash Disposal Regulations ............ 2-31
2.6 Energy Policies in the Study Area ........... 2-34
2.6.1 Introduction 2-34
2.6.2 Federal Energy Policies 2-35
2.6.3 Provincial Energy Policies in New Brunswick . . 2-36
2.6.4 State Energy Policies ..... . . 2-36
2.6.5 Exaraples of State/Provincial Energy Policies
Regarding Wood Combustion ........... 2-37
2.7 Bibliography - Chapter 2 2-39
2.7.1 Air 2-39
2.7.2 Solid Waste Regulations ............ 2-41
2.7.3 Energy Policies ................ 2-43
3.0 HARVESTED WOOD AND WASTE WOOD AVAILABLE FOR FUEL ...... 3-1
3.1 Introduction . 3-1
3.1.1 Key Issues Regarding Types and Amounts of
Waste Wood ......... ..... 3-1
3.1.2 Key Findings .................. 3-1
3.2 Types of Waste Wood ...... ....... 3-2
3.2.1 "Urban Wood Waste* ............... 3-3
3.2.1.1 Pallet Waste .............. 3-4
3.2.1.2 construction and Demolition Wood .... 3-4
3.2.1.3 Municipal solid Waste (MSW) Wood .... 3-5
3.2.2 Mill Residue 3-6
3.2.2.1 Primary Wood Products Industries .... 3-6
3.2.2.2 Secondary Wood Products Industries ... 3-6
3.2.3 Harvested wood ................. 3-7
3.2.3.1 Site conversion Waste Wood ....... 3-7
3.2.3.2 Silvicultura] Waste Wood ........ 3-8
3.2.3.3 Agricultural Residue .......... 3-8
3.3 Wood Fuel Available in the Study Area ......... 3-8
3.4 Industry Trends Affecting Waste Wood for Fuel ..... 3-10
3.4.1 Pallet Waste 3-11
3.4.2 Painted Wood 3-12
3.4.3 Plywood and Other Wood Panels ......... 3-13
3.5 Bibliography - Chapter 3 3-18
4.0 THE COMPOSITION OF HARVESTED WOOD AND WASTE WOOD ...... 4-1
iv
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Table of Contents, continued
Section gage
4.1 Introduction 4-1
4.1.1 Key Issues Regarding The Composition of
Waste Wood . 4-2
4.1.2 Key Findings 4-2
4.2 Wood Product Groups Containing Non-Wood Material .... 4-2
4.2.1 Structural Panels ............... 4-3
4.2.2 Non-Structural Panels ............. 4-3
4.2.3 Impregnated Wood 4-3
4.2.4 Surface-Coated Wood .............. 4-4
4.2.5 Wood Containing Physically Separable Items . . . 4-4
4.3 Components of Harvested Wood and Common Wood
Treatments 4-6
4.4 Adhesives Used in Wood Products 4-6
4.4.1 Formaldehyde Resins 4-6
4.4.2 Isocyanate, Bioresins, and Epoxy ........ 4-7
4.4.3 Other Adhesives ... ...... 4-9
4.5 The Composition of Wood Preservatives 4-9
4.5.1 Creosote Preservatives ............. 4-10
4.5.2 Oil-Borne Preservatives ............ 4-11
4.5.3 Water-Borne Preservatives 4-11
4.6 The Composition of Wood Coatings 4-12
4.6.1 Major Wood Coating Product Groups ....... 4-13
4.6.1.1 Paints and Stains ........... 4-13
4.6.1.2 Water-Based Coatings .......... 4-13
4.6.1.3 Lacquers ....... ... 4-13
4.6.1.4 Varnishes ............... 4-13
4.6.1.5 Enamels ................ 4-13
4.6.1.6 Polyurethar.es 4-13
4.6.2 Proportion of Materials in Paint ........ 4-14
4.7 Physical and Chemical Contents of Harvested Wood and Six
Common Wood Products .... ....... 4-15
4.7.1 Harvested Wood ................. 4-15
4.7.2 Pallets .................... 4-20
4.7.3 Painted Wood 4-20
4.7.4 Plywood .................... 4-21
4.7.5 Particleboard ................. 4-21
4.7.6 Pressure-Treated Wood ............. 4-21
4.7.7 Creosote-Treated Wood . 4-22
4-8 Bibliography - Chapter 4.0 .. 4-22
5.0 WASTE WOOD PROCESSING' FACILITIES ....... ... 5-1
5.1 Introduction ............ . ¦ . . 5-1
5.1.1 Key Questions Regarding Waste Wood Processing . 5-1
5.1.2 Key Findings 5-2
5.2 Hew Waste Wood Processors both Affect and are
Affected by Solid Waste Management Issues ...... 5-2
5.2.1 Major Factors Affecting Processors ....... 5-3
5.2.2 Policy and Regulatory Factors ......... 5-3
5.2.3 Factors Affecting Waste Wood Availability . . . 5-4
5.2.4 Factors Affecting End-Use Markets ....... 5-4
5.2.5 Factors Affecting Treated Waste Wood Processing 5-5
5.3 Types of Waste Wood Processing Facilities ....... 5-5
5.3.1 Mobile Waste Wood Processors .......... 5-6
5.3.2 Stationary Wood-only Processors . 5-8
v
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Table of Contents, continued
Section Pace
5.3.3 Stationary Multi-Waste Processors 5-9
5.3.4 On-Site Processors at Combustion Facilities . . 5-9
5.4 Processing Lines at Wood-only and Multi-waste
Facilities 5-10
5.4.1 How Processors Define "Clean." and "Treated" Waste
wood 5-10
5.4.2 Key Steps in a Processing Line ......... 5-11
5.4.3 Factors Affecting Removal of Non-Wood Material . 5-12
5.4.3.1 Redundancy 5-12
5.4.3.2 Time Spent at Cleaning Stations .... 5-12
5.4.3.3 Waste Wood Composition ......... 5-14
5.4.3.4 Equipment Design Capacity and Use . . . 5-14
5.4.4 Separating Wood from Non-Wood Substances .... 5-14
5.5 Waste Wood Processing Equipment 5-15
5.5.2 Waste Wood Sorting . 5-18
5.5.3 Primary Grinding Equipment ........... 5-19
5.5.4 Float Tanks ............. 5-20
5.5.5 Manual Picking Stations ............ 5-21
5.5.6 Mechanical Screening Equipment ......... 5-21
5.5.7 Metal Removal 5-22
5.5.8 Fuel Storage Systems 5-23
5.5.9 Dust Control Systems 5-24
5.6 Summary of Processing Facilities in the Study Area . . . 5-24
5.7 Case Studies of Processing Facilities ......... 5-24
5.7.1 Wood-Only Processing Facility ......... 5-24
5.7.2 Multi-Waste Processing Facility ........ 5-27
5.8 The Effect of Tipping Fees and Disposal Costs on Waste Wood
for Fuel . . .' 5-28
5.8.1 Tipping Fee Factors 5-29
5.8.2 Disposal Cost Factors ............. 5-31
5.9 Bibliography - Chapter 5 ............... . 5-32
6.0 WASTE WOOD COMBUSTION FACILITIES ............... 6-1
6.1 Introduction ................. 6-1
6.1.1 Key Issues Regarding Waste Wood Combustion
Facilities ................... 6-2
6.1.2 Key Findings . . - . . . , 6-2
6.2 Issues Aflecting Waste Wood Combustion ... 6-2
6.3 Wood Fuel Procurement ................. 6-4
6.3.1 Wood-Fired Power Plants ............ 6-4
6.3.2 Wood-Fired Industries ............. 6-5
6.3.3 Wood Fuel Procurement ............. 6-5
6.3.4 Wood Fuel Specifications ............ 6-7
6.3.4.1 Wood Chip size ............. 6-7
6.3.4.2 Moisture Content (MC) 6-9
6.3.4.3 Physical and Chemical Composition , . . 6-1
6.3.4.4 Potential Contaminants 6-10
6.4 Fuel Delivery, storage, and Feeding Equipment ..... 6-12
6.5 Combustion Equipment ...... ....... 6-14
6.5.1 Furnace ana Boiler Designs ........... 6-14
6.5.2 Grate Burning Systems ............. 6-14
6.5.2.1 Pile Burners .............. 6-17
6.5.2.2 Spreader Stokers ............ 6-17
6.5.3 Fluidized Bed Systems ............. 6-17
vi
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Table of Contents, continued
Section Page
6.5.3.1 Bubbling Bed Systems 6-22
6.5.3.2 Circulating Bed Systems ........ 6-23
6.5.4 conventional Suspension Burners 6-23
6.6 Sunroary of Waste Wood Combustion Facilities in the
Study Area 6-24
6.7 Case Studies of Combustion Facilities ......... 6-24
6.7.1 Fluidized Bed Combustion Systems ... 6-24
6.7.2 Underfeed Stoker Combustion System ....... 6-30
6.8 Bibliography - chapter 6 ............... . 6-31
7.0 CHEMICAL AND PHYSICAL PROPERTIES OF WASTE WOODS AND
THEIR ASHES ... ............. . 7-1
7.1 Introduction ...................... 7-1
7.1.1 Key Issues 7-3
7.1.2 Key Findings . 7-3
7.2 Statistical Sampling Techniques 7-4
7.2.1 Statistical Sampling Methods .......... 7-5
7.2.2 Statistical Concepts ........ 7-7
7.2.3 Compositing of Samples ............. 7-9
7.3 General Sampling and Analysis Plan ........... 7-9
7.3.1 Homogeneous Wood Types ............. 7-9
7.3.2 Waste Wood Processors ............. 7-10
7.3.3 Waste Wood Combustion Facilities ........ 7-12
7.4 Analytical Methods .................... 7-13
7.4.1 Ultimate/Proximate Analysis .......... 7-13
7.4.2 Elemental Metals Analysis {"five metals" and
•total metals") 7-13
7.4,2.1 Titanium Analysis 7-15
7.4.3 Phenols ........ 7-16
7.4.4 Laboratory Ash 7-16
7.4.5 Mineral Analysis 7-16
7.4.6 Toxicity Characteristic Leachate
Procedure (TCLP) ................. 7-17
7.5 Test Results ..... ............ 7-17
7.5.1 Homogeneous Wood Samples ............ 7-17
7.5.1.1 Ultimate/Proximate Analysis ...... 7-19
7.5.1.2 Phenols ..... 7-19
7.5.1.3 Minerals Analysis of Facility and Laboratory
Ash. 7-19
7.5.1.4 Elemental Metals Analysis ....... 7-20
7.5.1.5 Toxic Characteristic Leachate Procedure
(TCLP) ............ 7-20
7.5.2 Waste Wood Processors ............. 7-20
7.5.2.1 Processor - Site 1 .......... . 7-24
7.5.2.2 Processor - Site 2 . 7-28
7.5.2.3 Processor - Site 3 .......... , 7-32
7.5.2.4 Processor - Site 4 . 7-33
7.5.2.5 Processor - Site 6 ... . 7-39
7.5.2.6 Processor - Site 7 7-43
7.5.2.7 combination of Six Processors ..... 7-44
7.5.2.7.1 Ultimate/Proximate Analysis . , 7-47
7.5.2.7.2 Phenols Analysis . 7-51
7.5.2.7.3 Minerals Analysis 7-56
7.5.2.7.4 Metals Analysis ........ 7-56
vii
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i
Table of Contents, continued
Section Page
7.5.2,7,5 TCLP 7-57
7.6 Wood Fired Combustors 7-65
7.6.1 Minerals Analysis on Ash ............ 7-66
7.6.2 TCLP 7-66
7.6.3 Elemental Metals Analysis ........... 7-66
7.7 Sample Accuracy and Reproducibility 7-69
7.7.1 Laboratory Variability ............. 7-69
7.7.2 Split or Duplicate Analysis . 7-69
7.7.3 Minimum Detection Limits (MDL) ......... 7-70
7.8 Suggestions for Future Analysis 7-70
7.9 Bibliography - Chapter 7 ............... . 7-71
8.0 ENVIRONMENTAL, IMPACTS OF WASTE WOOD COMBUSTION - AIR ..... 8-1
8.1 introduction ...................... 8-1
8.1.1 Key Findings ............ 8-1
8.2 Identification of Pollutants from Waste Wood
Combustion ......... ........ 8-3
8.3 Sources of Emissions Data . 8-3
8.4 Data Collection Methodology .............. 8-13
8.5 Criteria Pollutant Permit Limits and Test Data ..... 8-14
8.6 Summary and Evaluation of Non-criteria Emissions Data . 8-14
8.6.1 statistical Analysis of Different Boiler
Designs .................... 8-20
8.6.2 Particulate and Metals Emissions ........ 8-20
8.6.2.1 Metals Emissions Estimated From Wood
and Ash Composition .......... 8-32
8.8.3 Organic Products of Incomplete Combustion . . . 8-33
8.6.4 Emissions From C/D, Railroad Ties and Other
Treated Wood Fuel ............... 8-39
8.7 Environmental Impacts ...... ..... 8-43
8.8 Bibliography - Chapter 8 8-48
appendices {in separate Volume 2)
Appendix A study Area Summaries
Appendix B Summary of Solid Waste Regulations in Each State/Province
Appendix C Waste Wood Generation and Eeuse in Each State/Province
Appendix D Examples of Specification for Waste Accepted for Processing,
Sample #1
Appendix E Fuel specifications
Appendix F statistical Procedures Use Sample and Value Data
Appendix G Detailed Sampling Results and Computerized Statistical
Calculations
Appendix H Emission Conversion Factors
viii
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LIST OF FIGURES
fjsp&b ¦ Earn.
5-1 Generic Wood Waste Processing Facility . 5-13
6-1 Examples of Waste Wood Fuel Handling Systems ........ 6-15
6-2 Additional Examples of Waste Wood Fuel
Handling Systems . . , . 6-16
6-3 Schematic of a Spreader Stoker ............... 6-18
6-4 Schematic of a Fluidized Bed Combustion System ....... 6-18
7-1 Sampling Terminology . 7-6
7-2 Normal vs. Lognormal Distributions 7-8
7-3 Wood Stockpile Sampling/Conveyor Sampling .......... 7-11
7-4 cambustor Ash/Wood 7-14
7-5 Variable Moisture ...................... 7-52
7-6 Variable Ash 7-53
7-7 Variable Chlorine 7-54
7-8 Variable Sulfur . 7-55
7-9A Composite Samples Frequency Histogram ............ 7-58
7-3B Incremental Sample;? Frequency Histogram ........... 7-58
7-1OA Ch romi'iim Composite Samples Frequency Histogram 7-59
7-103 Chromium Incremental Samples Frequency Histogram ...... 7-59
7-11A Lead Composite Samples Frequency Histogram 7-60
7-11B Lead Incremental Samples Frequency Histogram . , 7-60
7-12A Titanium Composite Samples Frequency Histogram ....... 7-61
7-12B Tit aiiium Incremental Samples Frequency Histogram ...... 7-61
7-13A Zinc Composite Samples Frequency Histogram ......... 7-62
7-13B Zinc Incremental Samples Frequency Histogram ........ 7-62
7-14 Barium Composite Samples Frequency Histogram ........ 7-63
7-15 Cadmium Composite Samples Frequency Histogram 7-63
7-16 Cooper Composite Samples Frequency Histogram ........ 7-64
7-17 Nickel Composite samples Frequency Histogram ........ ?~64
7-18 silver Composite Samples Frequency Histogram ........ 7-65
8-1 Distribution of Particulate Emissions by Control
Device ................... 8-27
8-2 Arsenic vs. Total PM 8-29
8-3 Total Chromium vs. Total PM ................ . 8-29
8-4 Copper vs. Total PM ............... . 8-29
8-5 Lead vs. Total PM {High Range} 8-29
8-6 Lead vs. Total PM (Low Range) ...... ..... 8-30
8-7 Zinc vs. Total PM (High Range) ...... .... 8-30
8-8 Zinc vs. Total PM (Low Range) . 8-30
8-9 Mercury vs. Total PM ...... ......... 8-30
8-10 Mercury vs. Temperature ................... 8-31
8-11 Total Hydrocarbons vs. CO 8-3S
8-12 Total Hydrocarbons vs. CO for Spreader Stokers. ....... 8-35
8-13 Forma 1dehyde vs, CO, All Data 8-40
8-14 Benzene vs. CO, All Data 8-40
ix
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LIST OF TABLES
TABLE Page
2-1 PSD Significant Emission Rates . 2-8
2-2 - Summary of National Ambient Mr Quality Standards
(NAAQS) and PSD Increments ........ 2-10
2-3 Comparison of Perr.it and PSD Trigger Levels .......... 2-H
2-4 Classification of Wood Fired Facility by
Fuel Type 2-13
2-5 Comparison of State Emission Standards (lb/MMBtu) ....... 2-14
2-6 Typical BACT Levels Based on Recent Permits 2-17
2-7 Comparison of Requirements for Hazardous Air
Pollutants 2-18
2-8 Comparison of Regulatory climate/Additional
Requirements 2-21
2-9 Selected Threshold Concentrations for Toxicity
Characteristics Under ECRA 2-24
2-10 summary of Solid Waste Management Strategies in the Study Area
Affecting Waste Wood Combustion and Ash Disposal. ....... 2-28
2-11 state Threshold Limits of Selected Inorganics for
Toxicity Characterization 2-33
2-12 Summary of Wood Energy Use and Energy Policy
in the Study Area ................ 2-38
3-1 Categories of Waste Wood 3-3
3-2 Summary of Combined Waste Wood Generation and Reuse in
the Study Area 3-9
3-3 Characteristics of Pallet Manufacturing in tie
Study Area 3-12
3-4 Plywood Production by Class and Region ............ 3-14
3-5 Production Reported by 462 Treating Plants,
by Region, 1989 3-16
3-6 Production of Treated wood in the United States, 1989 ..... 3-17
4-1 Physically Separable Items Contained in Waste Wood . , i , . . 4-5
4-2 Chemical Elements Used in Wood Products ....... 4-7
4-3 Chemical compounds Used in Wood Products ........... 4-8
4-4 Major Categories of Wood Preservatives ............ 4-10
4-5 Wood Coating Characteristics 4-14
4-6 Description of Resin Classes ....... . . 4-16
4-7 Characteristics of Common Wood Product Groups ......... 4-17
5-1 Types of Waste Wood Processing Facilities ........... 5-7
5-2 Representative Waste Wood Processing Facilities ......... 5-16
5-3 Waste Wood Processing Facilities in The Study Area 5-25
5-4 Examples of waste Wood Processing Facilities Outside
the Study Area 5-26
5-5 Tipping Pees in the Study Area ........ ... 5-30
6-1 Characteristics of Common Waste Wood Fuels 6-8
6-2 Example of Wood Fuel Specifications Used by a Proposed
Wood-Fired Power Plant ............. 6-11
6-3 Overview of Major Types of Combustion Systems
Used to Burn Waste Woodfuel .................. 6-19
6-4 Comparison of Major Combustion Characteristics Between
Grate-Burning and Fluidized Bed Waste Wood Combustion Systems . 6-21
X
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LIST OF TABLES, Continued
TABLE Page
6-5 Examples of Technologies Used toy "Large" Waste Wood
C ambus t ior. Systems; (>100 MMBtu) 6-25
6-6 Examples of Technologies used at "Medium" Size
Waste Wood Combustion Systems; {10-100 MMBtu) ......... 6-26
6-7 Examples of Technologies Used at "Small" Waste
Wood Combustion Systems; {<10 MMBtu) ..... 6-2?
6-8 Independent Power Plants that Burn Waste Wood
in the Study Area 6-29
7-1 Wood and Ash Analyses 7-2
7-2 Toxicity Characteristic Leaching Procedure . . ... 7-18
7-3 Homogeneous Woods Ultimate and Proximate Analysis (% wt as
received) . .................. 7-21
7-4 Homogeneous Woods Ultimate and Proximate Analysis (% wt dry) . 7-21
7-5 Homogeneous Woods Phenols and Chlorophenols Analysis ..... 7-22
7-6 Homogeneous Woods Mineral Analysis of Laboratory
Combusted Material and Facility Ash ......... 7-22
7-7 Homogeneous Woods Elemental Metal Analysis 7-23
7-8 Homogeneous Woods TCLP - Metals Only (rag/L) .......... 7-23
7-9 Wood Ultimate Analysis, Processor Site 1 ........... 7-25
7-10 Summary Data From Processor Site 1 " . 7-26
7-11 Processor Site 1 Average Incremental vs. Composite
Metals Analysis ........ ........ 7-27
7-12 Processor site 1 Toxic Characteristic Leachate
Procedure (TCLP) in Laboratory Ash {Heavy Metals) ....... 7-28
7-13 Wood Ultimate Analysis, Processor Site 2 ........... 7-30
7-14 Summary Data From Processor Site 2 .............. 7-31
7-15 Processor site 2 Average Incremental vs. Composite
Metals Analysis 7-32
7-16 Processor Site 2 Toxic Characteristic Leachate
Procedure (TCLP) in Laboratory Ash (Heavy Metals) ...... .7-33
7-17 Wood Ultimate Analysis, Processor Site 3 ........... 7-34
7-18 Summary Data From Processor Site 3 .............. 7-35
7-19 Processor Site 3 Toxic characteristic Leachate
Procedure (TCLP) in Laboratory Ash (Heavy Metals) ....... 7-35
7-20 Wood Ultimate Analysis, Processor Site 4 ........... 7-36
7-21 Summary Data From Processor Site 4 ... ...... 7-37
7-22 Processor Site 4 Average Incremental vs. Composite
Metals Analysis ........................ 7-3S
7-23 Processor Site 4 Toxic Characteristic Leachate
Procedure {TCLP} in Laboratory Ash {Heavy Metals) ....... 7-39
7-24 Wood Ultimate Analysis, Processor Site 6 ........... 7-40
7-25 Summary Data Prom Processor Site 6 ...... ... 7-41
7-26 Processor Site 6 Average incremental vs. Composite
Metals Analysis .... .............. 7-42
7-27 Processor site 6 Toxic Characteristic Leachate
Procedure (TCLP) in Laboratory Ash (Heavy Metals) ....... 7-43
7-28 Wood Ultimate Analysis, Processor Site 7 ........... 7-45
7-29 Summary Data Prom Processor Site 7 .............. 7-46
7-30 Processor site 7 Average Incremental vs. Composite
Metals Analysis . . . 7-47
7-31 Processor Site 7 Toxic Characteristic Leachate
Procedure (TCLP) in Laboratory Ash (Heavy Metals) ....... 7-48
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LIST OP TABLES, Continued
TABLE Page
7-32 Wood Ultimate Analysis, Combination of Six Processors ..... 7-49
7-33 Summary Data From Six Wood Processors 7-50
7-34 Combination of Six Processors Toxic characteristics
Leachate Procedure {TCLP) in Laboratory Ash . 7-51
7-35 Mineral Analysis On Ash Prom Two Wood Fired
Conbustors .......... ...... 7-67
7-38 Toxicity Characteristic Leaching Procedure (TCLP)
On Ash From Two Wood Fired Combustors 7-67
7-37 Metals in Wood Combustor Fuel or Ash (PPM} 7-68
8-1 Plant Information For Emissions Data sources ......... 8-5
8-2 Criteria Pollutant Permit Limits and Test Data ........ 8-15
8-3 Summary Statistics For Spreader Stokers ............ 8-21
8-4 Summary Statistics for Dutch ovens ........ 8-22
8-5 Summary Statistics for Fluidized Beds 8-23
8-6 Summary Statistics for Cell Burners 8-24
8-7 Suittnary statistics for Air Suspension ............. 5-25
8-8 Trace Metals Emission Rates vs. Total Particulate
Control Level ... ................. 8-26
8-9 Metals Control Efficiency with ISP .............. 8-31
8-10 Metals Control Efficiency Estimated from Database ....... 8-32
8-11 Estinated Metals Emissions Based on Wood Analysis
Data from Six Processors • 8-33
8-12 organic Emission Rates vs. CO Stack
Concentration - All Boilers . . ......... 8-36
8-13 Organic Emission Rates vs. CO Stack
Concentration - Spreader Stokers ....... 8-37
8-14 Organic Emission Rates vs. CO Stack
Concentration - Pluidized Beds 8-38
8-15 Plants Burning C/D, Railroad Ties, and
Other Treated Wood ...................... 8-41
8-16 Average of Test Data for C/D, RR Tie,-and
Other Treated Mood Combustors ................. 8-42
8-17 Assumptions for Ambient Impact Analyses ............ 8-45
8-18 Air Quality Impact Analyses Short-Term {1-Hour)
Ambient Impacts ............. 8-46
8-19 Air Quality Impact Analyses of Annual Ambient Impacts ..... 8-47
xii
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83dCDTI¥B SUMMARY
Defining "Clean" and "Treated" Wood
This study, completed in mid-1992, emphasizes understanding the
differences in air emissions and ash characteristics from the combustion
of "clean" wood compared to "treated" wood. Clean and treated wood are
produced by a variety of municipal, commercial, industrial,
agricultural, construction, and demolition activities. Treated wood is
commonly referred to as "urban," "recycled," "treated, * "dirty," and/or
"demolition" wood. "Clean" wood is a by-product of harvesting
activities connected with forest management, commercial logging, and
site conversion. Harvested wood may be in the form of chips or stumps.
In most states evaluated in this study, the source and type of wood fuel
affects the environmental permitting of facilities. Each state or
province has either developed definitions for different wood fuels, or
classifies combustion facilities according to the type of wood fuel
burned. For this study and the final report, wood fuel types are
divided into "clean" cr "treated" wood, "Clean" wood is untreated and
uncontaminated natural wood,
• "Clean* wood is generated by primary wood-products
industries and some secondary wood-products industries. The
resulting mill residue may consist of bark, chips, edgings,
sawdust, shavings, or slabs. "Clean" wood is also generated
by municipal, commercial, industrial, agricultural,
construction, and demolition activities. This wood often
ends up in the solid-waste stream, and consists of used
pallets, dimensional lumber, and other untreated wood.
• "Treated" wood, cr wood that has been treated, adulterated,
or chemically changed in some way, includes material treated
with glues, binders, or resins, such as plywood,
particleboard, and wood laminates. "Treated" wood also
includes material treated with paints, stains, or coatings,
such as painted wood, stained wood, and plastic laminates.
"Treated" wood also includes material impregnated with
preservatives, such as creosote, pentachlorophenol, and
chromated copper arsenate (CCA), in railroad ties, marine
pilings, utility poles, and exterior-grade plywood.
Construction and demolition waste may contain "treated"
wood.
In this report, wood is referred to as "waste wood" when it is in its
pre-processed form, and as "processed wood" when it has been prepared
for fuel.
Federal, State, and Provincial Regulation*
The project team reviewed existing federal, state, and provincial air,
solid waste and energy policies, and regulations that relate to waste
wood processing and combustion facilities, identified major trends in
policies that affect the processing and use of waste wood for energy,
and investigated ash disposal from waste-wood combustion facilities.
Major air quality regulatory issues that affect waste-wood combustion
facilities include;
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• Regulatory implications for permitting a "treated" or a
"clean" wood combustion facility,-
• The level of control and/or control equipment currently
considered best available control technology; and
• Implications of the 1990 Clean Air Act Amendments for new
and existing wood-combustion facilities.
Major findings developed from a review of federal and state air quality
regulations include;
• Each state's air pollution regulatory agency has either
developed definitions for different wood fuels or classifies
facilities according to the type of wood fuel burned.
Permit review procedures are generally more difficult and
permit requirements more stringent for facilities burning
"treated" wood (e.g. lower emission limits, additional
controls, additional testing and record-keeping
requirements) than for facilities burning "clean" wood,
• With the exception of California, "clean" wood-fired energy-
recovery facilities are classified as wood boilers or
combustion equipment compared to solid-waste combustors or
incinerators. Burning "treated" wood is classified
differently in some states, even when energy recovery is
included.
• All wood-fired facilities in California are classified as
resource-recovery facilities, along with municipal solid-
waste incinerators, tire burners and sludge incinerators,
subjecting them to the same level of agency review and
public scrutiny as solid-waste incinerators.
• Best Available Control Technology (BACT) is required in most
states regardless of whether Prevention of Significant
Deterioration (PSD) applies. BACT-derived emission 1 in-,its
are usually much more stringent than federal New Source
Performance Standards (NSPS) and state emission standards.
Typical add-on control requirements for new facilities
include electrostatic precipitators (ESPs) or baghouses for
particulate control and selective non-catalytic reduction
(SNCR) for nitrogen oxides (NOx) control. Good combustion
design, including selection of the combustor type, is
usually required for carbon monoxide (CO) and volatile
organic compounds fVQC) control,
• The non-attainment provisions of the 1990 Clean Air Act
Amendments are not currently in effect. However, by
November 15, 1992, new wood-fired combust.ors in areas not
meeting NAAQ5 for ozone may require some combination of
additional controls and emission offsets for VOC and/or NO*
emissions. The requirement for and/or degree of controls
and offsets are functions of the classification or severity
of non-attainment in the area, the quantity of VOC and NOx
emissions from the facility, and the area s mix of ambient
NOx and VOC concentrations.
• Hazardous air pollutant regulations are currently being
written by the United States Environmental Protection Agency
(EPA) pursuant to Title III of the 1990 Clean Air Act
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Amendments. Based on discussions with EPA, wood-fired
boilers are in a subcategory of sources for which Maximum.
Achievable Control Technology (MACT) standards will be
established by November, 2000. Other relevant provisions of
the 1990 Clean Air Act Amendments including Title I
{attainment and maintenance of National Ambient Air Quality
Standards (NAAQS)) and Title V (Permits), will be
administered by State programs.
• All states in the study area have hazardous air pollutant
regulatory programs that are more comprehensive, than current
Federal National Emission Standards for Hazardous Air
Pollutants iNESHAPS) . Pollutants usually associated with
wood-fired facilities that are regulated include benzene,
formaldehyde, acetaldehyde, and trace metals, Polynuclear
aromatic hydrocarbons, dioxins and furans are also
regulated, although available data (see Chapter 8) indicate
that these compounds are usually not detected in significant
amounts. Each state has developed acceptable ambient
concentrations for hazardous air pollutants based on
occupational exposure limits or toxicity studies. New
Brunswick, Canada currently has draft guidelines for
limiting stack emissions of formaldehyde and hydrogen
chloride from wood-fired facilities.
Major solid-waste management issues that affect using wood for fuel,
particularly treated wood, include:
• Characteristics of ash from waste-wood combustion
facilities, and ash management and disposal methods required
by federal, state, and provincial environmental regulations;
• Regulatory classification of processing and combustion
facilities that prepare, burn, or intend to burn waste wood;
• Effect of recycling policies on the extent of waste wood
processing for use as fuel; and
• Regulatory distinction or lack of distinction between
•clean," untreated waste wood, and "treated" waste wood.
The effects of solid-waste policies and regulations on processing and
using waste wood for fuel are:
• Ash f rom waste-wood combustion is not currently defined by
the federal government in either the U.S. or Canada as
having hazardous waste characteristics. However, some
states require testing ash produced by waste-wood combustion
facilities to determine its characteristics and potential
toxicity. The Toxicity Characteristics Leaching Procedure
(TCLP) is commonly used. Ash that fails the TCLP teat is
classified as hazardous material, and must be handled and
disposed of accordingly. There are no ash characterization
requirements in New Brunswick province. Federal
"guidelines" have been developed only for municipal solid
waste (MSW) ash in Canada.
• Fuel processed from waste wood and ash from waste-wood
combustion are usually defined at the state or provincial
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level as solid waste which affects the classification of
waste-wood processing facilities and combustion facilities.
For example, some states and provinces view waste-wood
combustion essentially the same as MSW incineration and
regulate and permit a waste-wood combustion facility similar
to a MSW incinerator. Other states distinguish wood-fired
facilities from MSW incinerators, and do not regulate and
permit them in the same way. How a waste-wood combustion
facility is classified by a state can greatly affect the
level of regulatory review, type of permitting process, and
overall public acceptance.
• State and provincial recycling policies usually do not
define processing and using waste wood for fuel as
recycling. For states or provinces that require that
certain materials, such as wood, be recycled, policies may
restrict, or prevent the amount of waste wood that is
processed for fuel. In addition, public and regulatory
acceptance way be problematic for processing and combustion
facilities if they are considered as only "disposing of
waste" rather than recovering or recycling wood for energy,
• Some states and provinces have, or are beginning to
establish, preferences for certain types of combustion
activities due to: the recognition in some states of key
differences in combustion and emissions performance between
waste wood and MSW; favorable net environmental impacts of
processing and using waste wood for energy compared with
some fossil fuel sources; and the impact of processing waste
wood for energy on decreasing pressure on existing solid
waste disposal capacity.
Types and Amount* of Waste Wood Available for fuel
This study compiled data on the types and amounts of waste wood
currently generated and used for fuel in the eight-state, one-province
study area to estimate the amount of wood separated from the waste
stream and processed into fuel. This wood is derived from a variety of
forest harvesting, municipal, commercial, industrial, agricultural,
construction, and demolition activities. Identifying the types and
amounts of waste wood that may contain non-wood materials or
"contaminants," such as Paint, stain and preservatives is emphasized.
Information from state energy offices, forestry and wood use experts,
solid-waste managers, forest products industries, and published research
on forestry and waste-wood resources is included.
Major categories of waste wood that may be available for fuel,
particularly those potentially containing materials that may limit or
prevent their use, are identified. The different types of waste wood
generated and used for fuel in the study area are identified. Typical
wood products likely to be found in the waste stream are discussed.
The three major categories of waste wood include 'urban wood waste,"
mill residue, and harvested wood waste. "Urban wood waste" ia
presented in quotes because it is commonly used by energy and solid-
waste planners; however, it does not have a consistent definition.
Urban wood waste generally refers to wood found in the solid-waste
stream that is generated by municipal, commercial, industrial,
agricultural, construction, and demolition practices.
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Of the three major categories of waste wood, urban wood waste is most
likely to contain treat fid wood products. To a lesser extent, treated
wood may also be present in mill residue produced by secondary wood
products industries. Within the eight-state, one-province study area,
it is estimated that urban wood waste and secondary mill residue
comprise approximately 15 percent of total waste wood generation. It is
important to note this estimate represents a snapshot of waste wood
generation in 1990. Historical data or trends were not developed or
analyzed for this study.
O'f the total amount of waste wood estimated used for fuel in the study
area in 1990, 17 percent was derived from urban wood waste and secondary
mill residue. The remaining 83 percent came from harvesting operations
and mill residue from primary wood products industries. The study
revealed that data on the amount of specific types of treated wood
products in the waste stream are not readily available at the federal,
state, or provincial levels. Some information is available on the
regional level; however, the regions are inconsistent among various data
sources. Key factors that affect the types and amounts of wood
products and potential contaminants in a waste stream include: the type
and extent of wood product industries in operation; the level of
construction, demolition, or shipping activities in a region; and
climatic characteristics that affect the choice of building materials
such as the increased use of pressure-treated wood in humid climates.
Composition of Waste Wood
The study identified specific types of waste wood materials that are
treated in some way and which are commonly found in solid-waste streams
including:
• Wood products manufactured with glues, binders, or resins,
such as structural and non-structural panels (e.g. plywood,
particleboard, masonite, waferboard, and wood laminates);
• Wood products treated with paints, stains, or coatings,* and
• Wood products impregnated with preservatives such as
creosote, pentachlorophenol, or CCA {e.g. railroad ties,
utility poles, and exterior grade lumber).
Information and product-specific data were obtained from industry
reports, sales representatives, research chemists, state and federal
government research scientists, and others. A summary of common wood
products and the level and types of non-wood contaminants is provided in
Table 4-7.
Major issues affecting the use of waste wood (especially treated wood)
for fuel are the types and amounts of potential contaminants contained
in the material; and the physical, chemical, and environmental
characteristics of the contaminant. Overall, the study determined that:
• Adhesives used in wood products manufacturing are primarily
interior grade urea resins (61 percent) and, to a lesser
extent, phenolic and resorcinol resins (3? percent) and
isocyanate resin (2 percent). However, 96 percent of
plywood and strandboard products manufactured in the U.S. in
1991 use phenolic resins. The proportion of adhesive ranges
from 2 to 15 percent by weight depending on the product.
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• ' Many different types of waste wood are treated with surface
coatings. However, surface-coated wood contains the lowest
percentage of non-wood contaminants compared to other types
of treated wood. Surface-coated wood usually contains less
than 0.1 percent of r.on-wood contaminants based on weight.
Of common paint formulations, approximately 5 0 percent are
made up of binder resins and fillers; primary and secondary
pigments make up the remaining 5G percent. Paints are
increasingly water-based due to restrictions on VOC
emissions. A common primary pigment is titanium dioxide,
while secondary pigments may contain other metals.
Secondary pigments are typically less than 5 percent of the
overall paint mixture. Old painted wood, particularly from
buildings constructed before 1950, may contain significant
quantities of lead-based paint, up to 20,000 parts per
million (ppm).
• Impregnated wood consists primarily of oil-borne
preservatives, such as creosote and pentachlorophenol, and
water-borne preservatives, such as CCA. Overall, 75 percent
of all wood preservatives us*d for impregnating wood art
water-borne formulations of CCA,
Waste-Hood Processing Facilitioa
The study investigated facilities that collect, sort, and process waste
wood for fuel. site visits to six processing facilities in the 0.S. and
Canada were conducted. In addition, processing equipment manufacturers,
solid-waste regulators, and facility owners and operators that were not
visited were inter-viewed.
Research focussed on investigating regulatory and economic issues that
affect the ability of processors to use wood from the waste stream;
determining the types and sizes of facilities that process waste wood in
the study area; and identifying the major types and capabilities of
equipment and systems used to process wood for fuel.
The study determined that operation of a waste-wood processing facility
is contingent on many factors including the economic and regulatory
climate that affects the types of waste wood available to processing
facilities; way {s) in which recycling and' solid-waste management
authorities permit a processing facility; and the size and
specifications of markets that use processed waste wood for fuel or
other uses.
Waste-wood processing methodologies, equipment, and systems are evolving
to meet the requirements of various end-use markets. Facility operators
are becoming more specific about the types of wood accepted for
processing. The level of inspection and enforcement of unacceptable
Materials prior to processing is an important step in achieving and
maintaining the quality and specifications required for fuel and other
end-use products.
Waste-wood processing methodologies, equipment, and systems vary among
facil ities. In general, there are four major types of waste wood
processors:
• Mobile waste wood processors - that often consist of
portable hogs, hamro®rmills or tub grinders. Commercial- or
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industrial-scale machines may also have the capacity to sort
or screen for non-wood contaminants.
• Stationary wood-only processors - that frequently have one
primary processing line. They may have two "finishing
lines," depending on the availability of markets, such as
fuel, compost, or landscaping.
• Stationary multi-waste processors - that collect, sort, and
process a range of materials, such as source-separated or
mixed construction and demolition (C/D) debris. Waste wood
is only a portion of the material accepted and processed.
• On-site processors at combustion facilities - a growing
number of utility-scale waste-wood combustion facilities
maintain wood-processing systems to ensure the availability
and proper preparation of wood fuel used in the combustion
unit. This represents a significant increase in capital and
operating expenses, and results in additional permitting
requirements, especially if the facility handles treated
waste wood.
Waste-Wood Combustion Facilities
Combustion facilities that burn, or intend to burn, processed waste wood
for fuel were researched and identified in the study area. Data on the
capacity of the facility, type of fuel handling, combustion, and
pollution control equipment used, and stack emissions and ash
characteristics were collected. Research techniques included surveying
commercial and industrial wood energy facilities; conducting site visits
to two combustion facilities in the U.S. and Canada; completing
telephone interviews with plant engineers, equipment manufacturers, and
air-quality regulators; and reviewing published research about the
performance of various wood-combustion systems.
The study identified key issues concerning fuel specifications and
procurement, fuel delivery and feeding equipment, and furnace and boiler
designs for combustion facilities that use processed wood for all or
part of their feedstock. The study focussed on utility-scale power
plants that burn processed wood exclusively for electrical generation,
and industrial facilities that burn processed wood to produce thermal
and/or electrical energy. In particular, the project team investigated
which issues affect the decision to procure and burn processed waste
wood.
The decision to use processed waste wood for fuel, especially treated
wood, is primarily affected by the fuel requirements of the combustion
system; availability of fuel from untreated waste wood; local air
quality conditions and local environmental regulations and standards,-
and the familiarity of state, provincial, or local regulatory
authorities with waste-wood combustion technologies and facilities.
From the perspective of combustion facility operators, three aspects of
wood combustion using processed waste wood, especially treated waste
wood, are unique.
• First, fuel specifications are likely to be .more specialized
for facilities that rely on multiple sources of processed
fuel generated off-site to maintain permit standards and
minimize wear on fuel handling and combustion equipment.
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• Second, due to current testing and regulatory steps, most
facilities that use significant amounts of processed waste
wood, including treated wood, are utility- or
industrial-scale independent power plants or cogeneration
facilities that are larger than 100 MMBtu/hr. (An exception
may be secondary wood products industries that burn treated
waste wood that is primarily generated on-site. Many of
these facilities operate under environmental permits that
are currently "grandfathered,")
• Third, when burning process ed waste wood, most facility
operators believe they can meet air standards through a
combination of adjustments in combustion unit parameters and
careful monitoring of fuel quality, rather than by making
fundamental equipment changes in their overall system.
Two major types of combustion systems are used for processed waste wood,
thin- or thick-bed grate-fired systems, and bubbling or circulating
fluidized bed systems. Each system has certain advantages and
disadvantages based on the type of fuel used, location, and operating
experience. Similar to processing facilities, the diversity in
combustion equipment allows project developers to match fuel and
combustion system characteristics. For a variety of reasons, processed
waste wood is rareiy used as the only fuel source. The primary
exception is small- and medium-size wood products manufacturing boilers
that use one or more sources of mill residue generated on-site.
Processed waste wood at large facilities is typically co-fired with
"clean" harvested wood, mill residue, coal, or MSW.
Chemical and Physical Properties of Waste Wood and its Ashes
The chemical and physical properties of waste woods and the ash produced
from their combustion were evaluated. There is limited information
available in the technical literature. There is some information on
•clean" wood but it. is also extremely limited and not completely
applicable to waste-wood combustion. Since there is an increased
interest in using waste wood to produce energy, it is important to
understand its properties to predict the environmental impact from its
burning.
The type of information gathered for this study is needed to evaluate
th e emission of trace metals due to combustion of waste wood and to
understand the metal contaminants in the ash. The waste wood data
collected can be used by developers, regulators and others:
• to evaluate combustion and pollution control alternatives;
• to predict: air pollution, emissions and ash properties from
the combustion of waste woods and;
• to evaluate the environmental impacts from the combustion of
waste woods.
This study used random sampling techniques to obtain waste wood and ash
samples from six waste-wood processing and two combustion facilities
that employed various processing and combustion methods. Samples
gathered at these facilities were then finely ground, blended and
analyzed to obtain information on their chemical and physical
properties. Ash samples were obtained from combustion facilities and
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also by laboratory ashing the collected waste wood samples. The data
collected include:
• Chemical and physical properties of waste woods, their
variance and ranges;
• Statistical significance of the analytical data;
• Values for specifying a waste-wood combustion system and its
emissions; and
• Recommendations on limiting variability of waste-wood
properties.
Waste-wood samples were collected from various types of wood- processing
facilities. By reviewing the descriptions of the processors and
evaluating the data collected at each individual facility the reader can
make conclusions based on the types of waste woods processed and the
processing methods used. This information will toe helpful in designing
future waste-wood processing systems and in understanding the quality of
waste wood fuel which could be produced.
As part of this study homogeneous waste wood samples were collected and
analyzed. Some of these samples were collected from facilities also
burning these homogeneous materials. In those instances ash samples
were also collected and studied. The following types of homogeneous
waste woods were collected and analyzed:
• plywood;
• CCA pressure-treated wood;
• particle board;
• creosote-treated wood;
• furniture scraps; and
• laminated woods.
Major findings from this study include;
• .Data about energy values, chemical and mineral analyses and
concentration of metal contaminants -in "clean" and "treated"
wood and their ashes;
• Data about energy values, chemical and minerals analyses and
concentration of metal contaminants in homogeneous wood
types and their ashes;
• The variability of the preceding physical and chemical
parameters in the waste-wood fuel stream at each specific
test site and among the various sites tested. These
parameters and their variability are important factors in
the design of waste-wood processors and combustion
facilities; and
• Suggested values of the physical and chemical parameters for
specifying a waste-wood combustion system's environmental
emissions.
Environmental Impacts of Wasta-vrood Combustion - Mr
Emissions of heavy metals, sulfur, and chloride from the combustion of
waste wood in boilers can be approximated using wood and ash
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concentration data developed for this study. These data, and
conservative observations about partitioning these compounds between
bottom and fly ash, can be used to estimate air emissions. Worse case
assumptions about the partitioning; e.g., 100 percent of metals are
contained in the fly ash, can be used for overestimates of emission
rates; however, emissions of organic compounds can not be estimated from
wood and ash composition data.
Actual emissions data from testing existing wood boilers has been
compiled to supplement the wood and ash concentration data gathered for
this study. While emissions data for criteria pollutants such as
particulate matter, nitrogen oxides, carbon monoxide, sulfur dioxide and
total hydrocarbons were obtained, this study focused on non-criteria
pollutants such as metals and various organic compounds that are
regulated as hazardous air pollutants (HAPs} by most state agencies.
In the absence of HAP emissions data for wood boilers, regulators have
used test data from residential wood combustion appliances to quantify
emissions. Although these data may be useful in identifying the types
of pollutants that may be products of wood combustion, the emission
rates from industrial wood-fired boilers are significantly lower due to
the differences in combustor design, combustion efficiencies and
operating conditions. The overall objective of compiling emissions data
for this project, therefore, was to summarize available HAP emissions
data that are more applicable to commercial or industrial wood boiler
facilities. The objectives of this study were;
• fo identify pollutants that could be emitted from combustion
of various waste woods;
• To compile available test data on emissions from different
wood boiler designs firing different types of waste-wood
fuels;
• To summarize test data using consistent units of measure and
reference;
• To identify and evaluate operating variables that affect the
levels of pollutants formed and emitted;
• To compare emissions from commercial/industrial wood boilers
to those from residential wood-combustion appliances; and
• To evaluate the capability of different boiler designs and
waste-wood fuels to meet regulatory standards.
Key findings developed during this study include;
• Criteria and non-criteria pollutant emissions data from more
than 100 wood combustors are summarized into consistent
units. The data should be useful when characterizing
emissions from wood combustors. However, the statistical
summaries should be used with caution due to the wide
variation in boiler designs, sizes, fuel sources and
combustion controls represented by the many data sources.
• Few sources of emissions data were available on combustion
of C/D, railroad ties, telephone poles or other "treated"
wood. Comparing these data with data from "clean" wood
combustion at the same sources indicates that organic
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emissions are generally not increased from combustion of
"treated" wood. While metals emission data from these
sources were very limited, they indicate only slightly
higher levels for "treated* wood combustion,
• Organic compounds regulated as hazardous air pollutants that
have been measured in detectable amounts in wood-combustor
flue gas include aldehydes, benzene, phenol, and poiynuclear
aromatic hydrocarbons {PAH). These compounds are products
of incomplete combustion and a function of wood composition
or source, but are apparently correlated to emissions of
carbon monoxide and total hydrocarbons, which also indicate
combustion efficiency. "Good" combustion conditions
apparently minimize organic emissions.
• Metals usually found in wood combustor particulate include
arsenic, chromium, copper, lead, zinc, aluminum, titanium,
iron, and manganese. Emissions estimated from wood and ash
composition data summarized in Chapter 7 indicate that C/D
wood samples obtained for this research probably contained
higher concentration of metals than wood fuel combusted at
facilities for which emissions data were available.
• Particulate emissions vary according to the type of
particulate control device. Electrostatic precipitators and
baghouses perform the best, followed by wet scrubbers and
mechanical cyclones.
• Metals-control efficiency is apparently roughly equivalent
to total particulate control efficiency with the exception
of mercury.
• Chlorinated organic compounds such as dioxins, furans,
polychlorinated biphenyls, chlorinated phenols and chlor-
benzenes are usually measured at extremely low
concentrations or were reported at less than minimum
detection limits.
• Combustion of wood fuel with, high levels of C/D or "treated*
wood, particularly CCA wood, may exceed state guideline
concentrations. Exceedances of arsenic and chromium
guidelines may mean that the amount of CCA treated wood in a
fuel stream may need to be reduced by good processing
practices to insure compliance with state air toxics
guidelines.
MOIOWLIDGEIIEIITS
This study was conducted as a joint venture by Environmental Risk
Limited (ERL) in Bloomfield, Connecticut and C.T. Donovan Associates
Inc. (CTD) in Burlington, Vermont.
The Principal Investigator for Environmental Risk Limited was Dr.
Richard Atkins, PhD, P.E. He was assisted by Michael I. Holzman, Senior
Associate; Steve Dwelly, Environmental Engineer; Michael Weinmayr,
Environmental Engineer; and Administrative Assistants Sherry Butch,
Barbara Martin, Beth Merit, and Kristine Mothersele.
The Principal Investigator for C.T. Donovan Associates Inc. was
Christine T. Donovan, President. She was assisted by Eric S. Palola,
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Regulatory Analyst; Jeffrey Fehrs, P.E., Solid Waste and Recycling
Analyst; and Dona Loso, Publications Assistant and Business Manager.
An Advisory Board provided valuable guidance throughout the project:
Russell O1Connell and Philip Lusk of the CONEG Policy Research Center,
Inc.; Steven Morgan of Citizens Conservation Corporation; Jennifer Snead
of the Virginia Department of Mines, Minerals and Energy; Phillip Badger
and David Stephenson of the Tennessee Valley Authority; Robert
McCril1 is, Brendan MacMillian and Cathy Zoi of the U.S. Environmental
Protection Agency; Andrew Baker of the U.S.D.A. Forest Products
Laboratory; Leonard Theran of G&S Mills, Inc.; Joseph Robert and Donna
Clarke of the Canadian Department of Energy, Mines and Resources;
Michael Charles of the American Wood Preservers Institute; and, Michael
Hoag of the National Particleboard Association.
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1.0 HIX80D0CTXGN
Waste wood represents an alternative to the combustion of fossil fuels
for many regions of the country. Environmental regulators and the
general public, however, are concerned that waste wood "contaminated"
with paints, resins, or preservatives may generate unacceptable
environmental impacts during combustion. Given the difficulty of
separating some non-wood materials from waste wood and the possible size
of the resource, it is important to investigate solutions to the
problems associated with combusting this material. This project,
completed in mid-1992, was designed to:
• Identify the types and amounts of waste wood available in
selected states and provinces.
• Review current and proposed environmental regulations that
do (or may} apply to waste-wood processing and combustion
facilities.
• Visit several representative processing and combustion,
facilities to review and characterize equipment and
techniques used to gather, sort, process, and combust waste
wood for fuel.
• Obtain and test representative samples of waste wood fuel
and ash, and analyze the physical and chemical properties of
the material.
• Evaluate air emissions and ash-disposal issues associated
with the preparation and combustion of waste wood for fuel.
• Collect air emissions data from, wood-combustion facilities
to evaluate the effect of boiler combustion factors on air
emissions.
1.1 the Defining of "Clean' and "Treated" Wood
This study emphasizes facilities that burn wood that is separated from
the waste stream and processed into fuel. The wood is derived from
municipal, commercial, industrial, agricultural, construction, and
demolition sources, and is commonly referred to as "urban," "recycled,11
•treated,* "dirty," and/or "demolition" wood.
In most states included in the study, the source and type of wood fuel
affects the environmental permitting of facilities. Each state or
province has either developed definitions for different wood fuels, or
classifies combustion facilities according to the type of wood fuel
burned. For this study and the final report, wood fuel types are
divided into "clean" and "treated" with the following definitions.
• "C1ean" wood is untreated and uncontaminated natural wood- It is a
by-product of harvesting activities conducted for forest
management, commercial logging, and site conversion. Harvested
wood may be in the form of chips or stumps. Clean wood is
generated by primary wood products industries and some secondary
wood products industries. The resulting mill residue may consist
of baric, chips, edgings, sawdust, shavings, or slabs. Clean wood
is generated by municipal, commercial, industrial, agricultural,
construction, and demolition activities. This wood often ends up
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in the solid-waste stream, and consists of used pallets,
dimensional lumber, and other untreated wood,
• "Treated" wood includes wood that has been treated, adulterated,
or chemically changed in some way. Treated wood includes material
treated with glues, binders, or resins, such as plywood,
part.i c 1 eboard, and wood laminates. Treated wood also includes
material treated with paints, stains, or coatings, such as painted
wood, stained wood, and plastic laminates. Treated wood also
includes material impregnated with preservatives, such as
creosote, pentachlorophenol, and CCA. Examples are railroad ties,
¦marine pilings, utility poles, and exterior-grade plywood. Both
construction and demolition waste can potentially contain treated
wood.
In this report, wood is referred to as "waste wood" when it is in its
preprocessed form, and as ''processed wood" when it has been prepared for
fuel. Until the 1980's, most facilities that used wood for fuel burned
primarily clean wood. to exception was secondary wood-products
industries that burned treated wood for fuel that was primarily
generated on-site. During the past decade, however, interest has grown
in both the public and private sectors in finding new uses for wood in
the solid-waste stream. This has stimulated development of wood-fired
power plants and industrial wood-energy systems that burn, or would like
to burn, wood separated from the waste stream and processed into fuel.
This wood may contain treated materials.
The types and amounts of clean and treated wood used at a wood-fired
facility will depend on the extent of forest harvesting, wood products
industry, agricultural, construction, demolition, and other activities
that generate waste wood in the area where the facility is located.
The report is based on a one-year study that included research on
technical, public policy, and regulatory issues that affect the
processing and combustion of waste wood for fuel. Types of waste wood
included in the study were;
• Pallets;
• Construction and demolition waste;
• Wood treated with paints or stains;
• Wood containing glues, binders, or resins {including plywood,
veneer, laminated wood, particleboard, and wood composites};
• Wood containing plastics or vinyl (including formica};
• Wood treated with preservatives (including chromium copper
arsenate {CCA}, pentachlorophenol or pressure-treated wood);
• Wood treated with creosote {including new or used railroad ties,
telephone poles or marine pilings}; and
• Mood treated with pesticides or fungicides {such as some orchard
trimmings and agricultural waste}»
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1.2 Research Methodology
The project's purpose was to provide environmental regulators, project
developers, and others with the necessary data to make decisions on
using waste wood materials as a combustion resource. Potential
environmental problems from the combustion of waste wood were identified
and potential solutions were addressed.
This study included a variety of research methodologies and activities.
The project team evaluated the specific types and quantities of waste
wood generated in the study area. The availability of wood from
municipal, commercial, industrial, agricultural, construction, and
demolition sources was estimated, Potential non-wood materials, or
contaminants, in various types of waste wood were identified. Existing
or proposed environmental regulations for facilities that process and/or
burn waste wood were reviewed.
The project team obtained, characterized, evaluated, and documented
equipment, and material flows at waste-wood processing and combustion
facilities. A variety of technical, operational, environmental, and
management factors that affect air emissions and ash characteristics
from burning waste wood were identified. Six waste-wood processing and
two waste-wood combustion facilities were visited, and samples of their
feedstock and/or their ash were obtained.
A sampling, laboratory testing, and analytical program for waste-wood
feedstock and ash was completed, and key characteristics of waste-wood
fuel and ash that potentially affect wood energy facilities were
identified. The sampling, testing, and analytical program included wood
from various processing and combustion facilities, as well as
homogeneous samples of specific types of waste wood treated with resins,
glues, and binders; paint or stain; and preservatives.
The laboratory data were used to estimate air emissions and ash
characteristics from the combustion of waste-wood fuel. Combustion
systems and pollution-control equipment were evaluated for their
abilities to reduce emissions and control ash composition to within
environmentally acceptable limits. 'Waste wood components of
environmental concern and specifications for future wood fuel use were
identified. A specific result of this project was identification of
combustion system operation parameters and air pollution control
technologies that can minimize the emissions of identified air
contaminants from the combustion of waste wood.
1.3 Study Area
The geographic area included California, Connecticut, Mew York, North
Carolina, Vermont, Virginia, Washington, Wisconsin, and New Brunswick,
Canada. The study was co-funded by the; lew York State Energy Research
and Development Authority; United States Environmental Protection
Agency; Canadian Department of Energy, Mines, and Resources; United
States Department of Energy's Regional Biomass Program; and the Virginia
Department of Mines, Minerals, and Energy.
1.4 Organization of the Final Report
The report is organized into eight chapters and eight appendices; the
first chapter is the introduction.
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Chapter 2 discusses key federal, state, and provincial air, solid waste,
and energy policies and regulations affecting the processing and use of
waste wood for energy.
Chapter 3 describes the types and amounts of harvested wood and waste
wood potentially available for fuel in the states and province studied.
The purpose of the chapter is to determine now much wood currently
generated in each state and province may contain non-wood material that
could affect its use as fuel.
Chapter 4 describes the composition of harvested wood and waste wood
that could potentially be processed and used for fuel. The purpose of
the chapter is to'identify the contents of harvested wood as well as
waste wood derived from wood products that were processed or treated in
some way. The focus of the chapter is on the presence of non-wood
material in common wood products, and on the composition of the non-wood
materials. The chapter is intended to assist solid waste and energy
planners, wood-fired facility developers, and regulatory officials in
understanding characteristics of wastewood that may affect its use as
fuel. ,
Chapter 5 describes facilities that collect, sort, and process waste
wood for fuel. Key steps used during processing and the sequence in a
processing line are explained. Information is provided on the design,
operation, and capabilities of specific types of equipment commonly used
by waste-wood processors.
Chapter 6 describes combustion facilities that burn waste wood for fuel,
emphasizing facilities that use wood that is separated from the waste
stream and processed into fuel as at least part of their feedstock. Key
issues concerning fuel specifications and procurement, fuel delivery and
feeding equipment, furnace and boiler designs, and pollution control
equipment are explained. The discussion applies to power plants that
burn, or intend to burn, processed wood for electrical generation, and
industrial facilities that burn, or intend to burn, processed wood to
produce thermal and/or electrical energy.
Chapter 7 describes the development, implementation and results of the
sampling program conducted to obtain quantitative data on the physical
and chemical properties of waste wood and the ash that is produced from
its combustion. The program entailed the collection and analysis of
wood and ash samples from various waste wood sources and combustors
within the US and Canada. Wood samples collected include a variety of
mixed stream waste wood as well as several pure wood product samples
such as CCA-treated and creosote-treated woods. Ash samples from waste
wood processors and from pure wood products were obtained by laboratory
ashing methods, whereas ash samples from combustors were collected from
these facilities' particulate control devices. The information is used
to evaluate the environmental impacts of waste wood combustion from the
emissions of trace metals and the disposal of combustor ash.
Chapter 8 presents the results and evaluation of a comprehensive survey
of emissions data from more than 100 operating wood-fired boilers.
Statistical summaries of the data are provided to evaluate the operating
and design variables that affect the levels of pollutants formed and
emitted. Although the majority of facilities represented by the
emissions data purportedly burn "clean" wood, limited data were found on
several facilities that had conducted test burns with C/D wood, railroad
ties and other "treated" wood. Using the organic emissions from the
data survey and metals emissions estimated from the wood and ash
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analyses presented in Chapter 7» two hypothetical cases representing
"good" combustion of C/D wood with high efficiency particulate controls
were modeled to estimate worst case ambient impacts. Ambient impacts
were then compared to state guidelines for hazardous air pollutants to
assess compliance potential.
Appendix A includes a description of key environmental policies and air
emissions regulations for each state and province in the study area.
Appendix B includes a description of key environmental policies and
regulations concerning solid waste management for each state and
province in the study area. Solid waste regulations can affect the
waste-wood feedstock and the management of ash combustion facilities
produce.
Appendix C includes more detailed information on the estimates of waste-
wood generation and reuse in each state and province presented in
Chapter 3,
Appendices D and E include specifications used for waste wood accepted
for processing into fuel.
Appendix F presents details on the statistical methods used to evaluate
data in the test program.
Appendix G includes details on how samples were collected and reduced at
each of the six processing and two combustion facilities.
Appendix H includes more detailed information about laboratory tests
done for this study.
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2.0 HNVraOHMBfEitt. REGULATIONS
2.1 Introduction
This section discusses current environmental regulations and trends ill the
permitting and operation of waste wood-fired facilities in the following eight
states and one Canadian province: California, Connecticut, New York, North
Carolina, Vermont, Virginia, Washington, Wisconsin and the Province of New
Brunswick", Canada.
Agencies in the study area with direct knowledge of waste wood-fired
facilities were contacted for the following information:
• Air and solid waste permitting requirements;
• Regulatory concerns;
• Public acceptance;
• Compliance methods and procedures;
• Ash handling and disposal methods
• Published policy documents;
• Emission testing results; and
• Fuel and ash analysis data.
Environmental regulations and the regulatory climate are constantly changing.
The research phase, including interviews of regulatory agency personnel and
review of regulations and permits was conducted in the summer of 1991.
The timing of this research is particularly important since the 1990 Clean Air
Act amendments passed on November 15, 1990. This legislation mandated
numerous regulations, some of which were proposed and/or implemented after the
research phase of this project, but before publishing this document. Whenever
possible, information was updated (to late 1992) and references were made to
impending changes in the regulations.
The reader should consider this information as highlighting major requirements
and issues. For permitting and compliance issues the reader should obtain the
current regulations for the particular location and not rely solely on the
data presented here.
When the research was completed, the information was analyzed and summarized
by state and province. The following subsections of this chapter analyze
federal, state and provincial;
• Air Regulations;
• Solid and Hazardous Waste Regulations; and
• Energy Policies,
Summaries of the regulations of the states and province in the study area are
given in appendices:
• Appendix A — Air Regulations; and
• Appendix B -- Solid Waste Regulations.
2.1.1 Key Issue® In Federal Air Quality Regulations
• Which federal air quality regulations are potentially applicable to a
waste wood combustion facility?
• What are the implications of the 1990 Clean Air Act Amendments on new
and existing wood combustion facilities?
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2.1.1.1' Key Findings
• Most federal {USEPA) air quality programs establish a framework of
regulation; states either adopted these regulations without modification
or make them more stringent. These programs include Prevention of
Significant Deterioration (PSD), National Emission Standards for
Hazardous Air Pollutants (NESHAPS), and non-attainment provisions. Each
cf these programs is potentially applicable to new wood-fired boiler
facilities depending on the site and quantity of emissions.
• New Source Performance Standards (NSPS) potentially applicable to wood-
fired boilers 'depending on size) include 40 CFR Part 60, subparts Db
and Dc. Emission standards for sulfur dioxide and particulate matter
included within these subparts apply to new facilities and are less
stringent than those usually required in recent state permits.
• Hazardous Air Pollutant regulations are currently being written by EPA
pursuant to Title III of the 1990 Clean Air Act Amendments. Based on
discussions with EPA, wood-fired boilers are in a subcategory of sources
for which Maximum Achievable Control Technology (MACT) standards will be
established by November, 2000. Other relevant provisions of the 1990
Clean Air Act Amendments including title 1 {attainment andxmaintenance
of National Ambient Air Quality
Standards (NAAQS)! and Title V {Permits}, will be administered by State
programs.
2.1.2 Key Issues In State Mr Quality Regulations
• What are the state regulatory implications for permitting a "treated"'
versus a "clean" wood combustion facility?
• What level of control and control equipment is currently considered Best
Available Control Technology(BACT)?
• What are the implications of the 1930 Clean Air Act Amendments on new
and existing wood combustion facilities.
2.1.2.1 Key Findings
• Each state's air pollution regulatory agency has either developed
definitions for different wood fuels or classifies facilities according
to the type of wood fuel burned. In general, permit review procedures
are more difficult and permit requirements more stringent for facilities
burning "treated* wood (e.g. lower emission limits, additional controls,
additional testing and record keeping requirement*) than for facilities
burning "clean" wood.
• All wood-fired facilities in California are classified as resource
recovery facilities, along with municipal solid waste incinerators, tire
burners or sludge incinerators. This classification subjects wood
combustion facilities to a similar level of agency review and public
scrutiny as solid waste incinerators,
• With the exception of California, "clean" wood-fired energy recovery
facilities are classified as wood boilers or combustion equipment
compared to solid waste combustors or incinerators. The classifications
differ in some states about burning "treated" wood, even when energy
recovery is included.
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• Best Available Control Technology {BACT) is required in most states
regardless of whether PSD applies. BACT-derived emission limits are
typi ca ny rau ch more stringent than federal NSPS and state emission
standards. Typical add-on control requirements for new facilities
include ESPs or baghouses for particulate control and selective non-
catalytic reduction (SNCR) for nitrogen oxides (N0X) control. Good
combustion design, including selection of the combuster type, is usually
required for carbon monoxide {CO) and volatile organic compounds (VOC)
control.
» As of this writing (mid-1992), the non-a 11 a inment provisions of the 1990
Clean Air Act Amendments are not in effect. However, by November 15,
1992, new wood-fired corabustors planning to locate in areas not meeting
NAAQS for ozone will likely require some combination of additional
controls and emission offsets for VOC and/or NQX emissions. The
requirement for and/or degree of controls and offsets are functions of
the classification (severity) of non-attai.nn.ent in the area, the
quantity of VOC and N0X emissions from the facility and the area's mix
of ambient N0X and VOC concentrations.
• All states in the study area have hazardous air pollutant regulatory
programs that are more comprehensive than current Federal NESHAPS.
Pollutants usually associated with wood-fired facilities that are
regulated include benzene, formaldehyde, acetaldehyde, and trace metals.
Polynuciear aromatic hydrocarbon, dioxins and furans are also regulated,
although available data (see Chapter 8) indicate that these compounds
are usually not detected in significant amounts. Each state has
developed acceptable ambient concentrations for hazardous air pollutants
based on occupational exposure limits or toxicity studies. New-
Brunswick currently has draft guidelines for limiting stack emissions of
formaldehyde and hydrogen chloride from wood-fired facilities.
• Connecticut has passed a law specifica ny excluding "treated" wood as an
acceptable fuel source for a wood-fired combuster. The number of
existing facilities permitted to burn "treated." wood in the study area
is extremely limited,
• The majority of states in the study area require permits to construct
and/or operate, regardless of facility size or emissions. Some states,
such as Connecticut, Washington, Vermont and Wisconsin have permit
trigger levels based on heat input or emissions rates.
2.1.3 Key Federal Solid Waste Issues
• What aspects of a waste wood combustion facility could be affected by
federal, solid waste regulations?
• If a wood fuel feedstock or combustion ash is defined as solid waste,
are hazardous waste rules and procedures applicable?
2.1,3.1 ley Findings
• Solid waste regulations may affect a waste wood combustion facility in
two ways. First, the waste wood feedstock used as fuel is usually
defined as a solid waste. Second, the ash produced, by a facility is
usually defined as a solid waste.
• Currently, waste wood ash is not categorically defined as a hazardous
waste by EPA. However, waste characterization of the ash may be
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required by federal or state authorities to determine if the material is
hazardous.
• TCLP testing for potentially toxic characteristics of ash may be
required, particularly for fuel feedstock, that .may contain chemical
compounds, heavy metals, or inorganic substances regulated by RCRA.
• Provisions of the current RCRA statute categorically exclude certain
types of waste wood or waste wood ash as being defined as a hazardous
waste including waste wood or waste wood ash derived from "household
sources, * such as wood from nrunicipal solid waste.
• Existing ash classifications for certain types of solid waste may change
during pending reauthorization of RCRA that may in turn affect the
classification of ash from treated wood combustion. RCRA
reauthorization is underway and may be completed in 1992,
2.1,4 Key Issues in State Solid Waste Regulations
• Are there regulatory definitions under solid waste rules that
distinguish "clean," untreated waste wood from "treated" waste wood? If
there are no definitions, it may be unclear how to review and permit a
waste wood processing or combustion facility.
• Are there regulations 'or policies specifically for the management and
disposal of construction and demolition waste? Is wood specified in the
state definition of C/D waste? C/D waste is often regulated less
stringently than other types of solid wastes. However, some types of
treated waste wood may not be included in the definition of waste which
is to be managed as C/D debris.
• Is waste wood processed for fuel defined as a recycling activity under
state recycling policies? Do state recycling targets and definitions
for recyclable materials encourage or prevent the processing and use of
waste wood for fuel?
• How do state solid waste programs evaluate waste wood combustion ash?
Do state standards differ from the federal RCRA program for the
management of solid and/or hazardous wastes?
2.1.4,1 ley Findings
• Definiti ons of waste wood, particularly those that distinguish "clean,"
untreated wood from treated waste wood vary in the study area. In
several states. there are no definitions.
• Depending on the approach of state solid waste management programs,
disposal of waste wood may be managed under several classes of landfill
or combustion facilities including C/D disposal facilities, "inert
debris," landfills, and solid waste landfills. Combustion facilities
that burn waste wood may be permitted as a wood residue, resource
recovery, or solid waste incineration facility.
• There are significant differences in combustion performance of
facilities that burn MSW for fuel (often referred to as waste-to-energy
plants) compared to utility and industrial scale facilities that burn
"clean'1 and/or "treated" waste wood for fuel. The differences are not
always recognized by permitting and regulatory agencies. The lack of
distinction between these two types of combustion facilities often poses
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problems in siting, permitting, and public perception, about using waste
wood for fuel.
• In the study area, with the exception of New Brunswick, the reuse of
waste wood for fuel is not a recycling activity. Source separation of
wood from the waste stream, however, is encouraged under state recycling
policies. All state solid waste programs in the study area discourage
combustion for energy recovery as an end use of recycled material.
However, some states are beginning to distinguish energy and
environmental preferences for certain types of combustion, such as those
that are primarily for energy recovery, not disposal, or those that have
low net environmental impact compared to other energy sources.
• Ash from waste wood combustion is typically regulated as a non-hazardous
material following the same waste characterization procedures used under
RCRA. Treated wood fuel sources may require hazardous waste
characterization for both fuel and ash as part of air and solid waste
permitting. Solid waste regulators are usually concerned with metals
concentrations and potentially high pH values in the ash.
2,1,5 Key Kn«rgy Policy Iaiuu
• Which major federal energy statutes affect the siting and construction
of waste wood power plants or industrial facilities? Do federal
statutes distinguish between clean and treated waste wood combustion?
• Do state energy policies cover waste wood combustion? Is there a
distinction between "clean" and "treated" waste wood combustion?
2.1.5.1 Key findings
• The major federal energy statute affecting wood energy projects is the
1978 Public Utilities Regulatory Policy Act (PURPA) which governs how
power is sold to utilities. PURPA applies to wood energy projects that
are designated as "qualifying facilities" for small power production.
Industrial and commercia 1 facilitie s are not affected by PUKPA unless
they sell power off-site.
• State public utility commissions (PUCs)' determine rates paid to wood
energy projects based on avoided cost calculations required under PURPA
and other state statutes. Until recently, the rates were based on
issues only concerning the cost, availability, and duration of the power
provided. Historically, rate-setting by PUCs has not distinguished
between the source of fuel, type of fuel, or environmental impacts.
• State energy policies and rate determinations by PUCs are increasingly
viewing some small power facilities as more desirable than others.
Projects that rely on renewable fuels, such as harvested wood and waste
wood, or which have low net environmental impacts compared to other fuel
sources, may receive tax credits, production incentives, or rate
subsidies that enhance the competitiveness of wood energy in utility
bidding.
2..2 Federal Ait Pollution Regulations
2.2,1 USEPA
EPA air pollution regulations potentially applicable to new or modified
wood-fired facilities are Mew Source Performance Standards (NSPS), National
Emission Standards for Hazardous Air Pollutants (NESHAPS) and Prevention of
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Significant. Deterioration (PSD) regulations. New source review and
nonattainroent regulations are implemented at the state or local level under
permit programs approved by EPA that are at least as stringent as the federal
requirements.
2.2.1.1 Mew Source Performance Standards
Depending on the heat input capacity, a waste wood-fired steam generating
facility may be subject to Standards of Performance for New Stationary Sources
{40 CFR Part 60) for steam generating units. New steam generating units with
more than 100 MMBtu/hr heat input capacity are subject to Subpart Db -
Standards of Performance for Industrial-Commercial-Institutional Steam
Generating Units. 'Facilities rated between 10 and 100 MMBtu/hr are subject to
Subpart Dc - Standards of Performance for Small
Industrial-Commercial-Institutional Steam Generating Units. Weed-fired
electric generating facilities are not subject to Subpart Da (Standards of
Performance of Electric Utility Steam Generating Units for which construction
commenced after September 18, 1978) as long as fossil fuel heat input (e.g.
coal, oil or natural gas co-fired with wood) does not exceed 250 MMBtu/hr.
Subpart E - Standards of Performance for Incinerators or Subpart Ea -
Standards of Performance for Municipal Waste Combustors are not applicable
because waste wood fuel does not meet the Federal definitions of solid waste
or MSW in these subparts. In fact, according to the definition given in
subpart Ea "construction/ demolition waste is"not considered MSW",
The following standards fin mid-1992) apply to steam generating units subject
to Subpart Db (> 100 MMBtu/hr);
Sulfur dioxide (SO,) 0.50 lb/MMBtu, if the facility co-fires with oil and
has an annual capacity factor of 30 percent or less
for oil.
Particulate matter (PM) 0.1 lb/MMBtu, if the facility has an annual capacity
factor greater than 30 percent for wood. 0.2 lb/MMBtu ¦
if less than 30 percent capacity factor for wood.
Nitrogen oxides (NOx) No standard is given for a wood-fired boiler or one
that simultaneously combusts gas or oil with wood if
the annual capacity factor is less than 10 percent for
gas or oil.
The following standards apply to steam generating units subject to Subpart Dc
U0 - 100 MMBtu/hr) :
Sulfur dioxide (S02) 0.50 lb/MMBtu or 0.5 weight percent sulfur for any
oil fired in the boiler.
Particulate matter (PM) 0.10 lb/MMBtu for facility with > 30 percent annual
capacity factor for wood. 0.20 lb/MMBtu if annual
wood capacity factor < 30 percent.
Nitrogen oxides (NO,) No NQX emission standard applicable to Subpart Dc.
It should be noted that NSPS are merely the starting point for establishing
emission limits for new wood-fired boilers. New sources undergoing state
permit review are usually restricted to more stringent emission limits based
upon a Best Available Control Technology evaluation (see Section 2.3).
2.2.1.2 national Emission Standard* for Hazardous Air Pollutants (NBSHAPS)
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NESHAPS have been developed by EPA (40 CFR Part 61> to regulate emissions of
eight specific pollutants in fourteen categories of sources {Subparts B
through W). Only one of the NESHAPS (Subpart €} may be interpreted as being
applicable to waste wood-fired facilities. Subpart C applies to emissions of
beryllium from incinerators, among other sources. According to the definition
of incinerator given in this NESHAP, "any furnace used in the process of
burning waste for the primary purpose of reducing the volume of the waste by
removing combustible matter", a waste wood-fired facility that is not used for
energy or steam generation would be subject to this regulation. Regardless,
no data has been found to indicate that beryllium would be emitted from a
waste wood-fired facility,
2.2.1.3 Maximum Achievable Control Technology (MACT) Standards
Due to the perceived ineffectiveness of the NESHAPs regulations, EPA will be
developing standards for specific source categories under the 1990 Clean Air
Act Amendments (CAAA) to regulate emissions of 189 hazardous air pollutants.
{It should be noted, however, that NESHAPS will generally remain applicable
until they are reviewed and revised pursuant to the 1990 CAAA). In writing
the 1990 CAAA, congress established an initial list of 139 hazardous air
pollutants, EPA was subsequently responsible for developing a list (by
November, 1991) of source categories that emit these pollutants and would be
subject to meeting emission standards. Industrial external combustion
boilers, a source category that includes wood-fired boilers, are currently on
EPA's list of potential sources to be regulated. According to EPA
(Svendsguard, 1992) emission standards for this source category will be
promulgated by November, 2000.
The emission standards, called Maximum Achievable Control Technology (MACT)
standards will be established for new and existing sources. The level of
control may vary depending on the size, type and subcategory of source and
whether it is new or existing. For example, MACT standards for new major
sources will not be less stringent than the maximum degree of emission control
that is achieved in practice by similar sources. The standard will take into
consideration the cost of achieving such emission reduction and any
environmental, health and energy impact. MACT standards for existing sources
may be less stringent ar.d dependent on the number of sources within a category
or subcategory. For category or subcategories with 30 or more sources, MACT
may be established based on the average emission limitation achieved by the
best 12 percent of existing sources.
The wood sampling and analysis portion of this study focuses on the trace
metal contaminants in waste wood and their resulting air emission potential
(see Chapter 7.0), Organic emissions have also been characterized by
compiling stack emissions data obtained from existing wood-fired facilities
throughout the world. Chapter 8.0 summarizes these data and discusses the
variables affecting the levels of emissions. Metal and organic emissions will
likely be subject to MACT emission standards.
2.2.1.4 Prevention of Significant Deterioration (PSD) Regulations
PSD regulations apply to the construction or modification of major sources
located in areas that are attaining ambient air quality standards or are
unclassifiable for at least one criteria pollutant. Most states have been
delegated authority by EPA to enforce the PSD regulations. Some of the states
have developed more stringent interpretations; for example# lowering the
emission rate threshold that defines a major stationary source subject to the
regul ation. A summary of EPA definitions and requirements follows.
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Since a waste wood-fired facility Is riot one of the 28 specific source
categories listed in the PSD regulations, a major stationary source is defined
as one that has the potential to emit 250 tons per year or more of any
pollutant regulated under the Clean Air Act, The more stringent definition
used in some states (e.g. Connecticut) is that any source emitting 100 tons
per year or more Of an attainment pollutant is considered a major stationary
source subject to PSD review. When a new source is subject to PSD regulations
for one pollutant, a pollutant applicability determination must be made for
emissions of other pollutants. To determine which pollutants are subject, to
PSD requirements, facility emission rates are compared to specific numerical
cutoffs. Table 2-1 lists the significant emissions increases for each of the
regulated pollutants. For each regulated pollutant emitted in significant
quantities, a Best Available Control Technology !BACT} analysis, air quality
impact analysis and additional .impact analyses (e.g. soils, visibility and
vegetation) must be performed.
Table 2-1. U.S. EPA prevention of significant deterioration (PSD)
emission rates.
1 Pollutant
Emission Rate, tons per year 1
(tpy) K
I Carbon monoxide
100
Nitrogen oxides
40
Particulates
25
Sulfur dioxide
40
Ozone1
40
Lead
0.6
Mercury
0.0004
Flourides '
3.0
Sulfuric acid mist
7.0
1 Volatiles organic compounds as methane.
EPA's definition of BACT is .."an emissions limitation... based on the maximum
degree of reduction for each pollutant subject to regulation under the Clean
Air Act which would be emitted from any proposed major stationary source or
major modification which the Administrator, on a case-by-case basis, taking
into account energy, environmental, and economic impacts and other costs,
determines is achievable for such source or modification...". In practice,
BACT requirements are imposed by most states even for non-major sources not
subject to PSD review. In fact, some states require application of BACT for
any source requiring a permit. Moreover, air pollution control agencies are
increasingly making BACT determinations that put less emphasis on cost and
energy impacts and more on whether a type of control or emission limitation is
feasible in practice. By requiring new sources to test for emissions, the
BACT determination process has been effective in increasing the stringency of
emission limits. In order to allow some safety factor in meeting emission
limits, equipment vendors continue to over design control equipment. This, in
2-8
-------
turn, further lowers tested emission levels, and causes reductions in BACT
levels.
The requirements for the air quality impact analysis for PSD sources are more
stringent than for non-PSD sources {i.e. non-major sources). Whereas maximum
ambient impacts from all sources of air pollution must comply with National
Ambient Air Quality Standards (NAAQS), PSD sources must go beyond
demonstration of compliance. PSD sources must demonstrate that emissions from
the proposed facility in conjunction with other nearby sources will not
violate the NAAQS and more stringent PSD increments. A comparison o£ NAAQS to
PSD increments is presented in Table 2-2, to applicant for a PSD permit roust
also assess the source's impact on soils and vegetation, analyze the air
quality impacts associated with direct growth created by the new source, and
assess the source's impact on visibility.
2,2.2 Canadian Mr Regulations
Federal Canadian regulations have limited authority compared to USEPA.
Regulations are developed and enforced on a provincial basis. Based on
discussions with Environmental New Brunswick, the Canadian Council of
Ministers of the Environment (CCME) have published Operating and Emission
Guidelines for Municipal Solid Waste Incinerators that would serve as a
benchmark in evaluating "treated" wood combustion.
In addition, Environment Canada is developing a priority substance list for 44
specific sources of air pollution. From discussion with regulators in the
Province of New Brunswick, PAH emissions from wood burners will be one of the
substances regulated by Environment Canada.
2.3 Comparison of Regulatory Mr Emission Requirements Within the Study Area
2.3.1 State and Provincial Air Regulations.
This section discusses similarities and differences in the permitting
requirements and regulatory climate for waste wood-fired facilities in the
study area. A summary for each state and province included in the study area
is presented in Appendix A. The comparative discussion is organized in the
same manner as the information included in the summaries.
2.3.2 Applicable Regulations
The Clean Air Act requires each state to submit to the EPA a State
Implementation Plan {SIPS for implementation, maintenance, and enforcement of
NAAQS in each air quality control region (AQCR), EPA also requires
nonattainment areas (areas not meeting NAAQS) to revise SIPs to reflect
amended federal criteria (see Table 2-2) The SIP establishes the control
strategies, emission limitations, and timetables for compliance and is the
regulatory framework for evaluating new sources for consistency with air
quality goals.
Because individual states are required to develop SIPs to meet national goals,
the state regulations have similar components. The basic components common to
all state regulations include new source review procedures, emission
limitations for criteria pollutants, and nonattainment regulations. As
discussed in Section 2,1, some states have been delegated authority by EPA to
enforce PSD, NSPS, and NF.SHAP regulations. In addition, most states {all
stares in the study area) have developed hazardous air pollutant regulations
applicable to a much larger group of compounds than the eight regulated by
NESHAPs. A comparison of hazardous air pollutant regulations among the states
in the study area is provided in Section 2,3,8,
2-9
-------
The majority of the states in the study area require permits to operate all
new wood-fired facilities, regardless of size (heat input capacity) or
emissions. All new sources (regardless of size or emission rate) in
California, New York, North Carolina, Virginia and Washington require permits
or certificates prior to construction or operation. Connecticut, Washington
and Vermont, however, have permit trigger levels based on heat input and/or
annual emission rates. Connecticut requires permits to operate for all new
wood-fired facilities with greater than 5 MMBtu/hr heat input or that emit
fable 2-2. Summary of National Ambient Mr Quality Standards {NAAQS) and PSD
increments as of mid-1992,
Pollutant
Averaging
NAAQS1 (UQ/m3)1
PSD increments (pg/mM3
time
Primary
Secondary
Class
I
Class
II
Class
III
Carbon
monoxide
8-hour
1-hour
10,000
40,000
Same as
primary
Hone
None
None
Lead
Calendar
Quarter
1-5
Same as
primary
None
None
None
Nitrogen
Dioxide
Annual
100
Same as
primary
2,5
25
50
Ozone4
1-hour
235
Same as
primary
None
Rone
None
PM105
Annual
24-hour
50
150
Same as
primary
4
8
1?
30
34
60
Sulfur
dioxide
Annual
24-hour
3-hour
80
365
None
None
None
1300
2
5
25
20
91
512
40
182
700
1 National standards, other than those based oil calendar quarter -or
annual averages, are not to be exceeded more than once a year
(except where noted}. . Primary standards are set at levels
designed to protect public health. Secondary standards are set
at levels to protest public welfare, {Sources U.S. Code of
Federal Regulations, 40 CFR 50.4-50.12.)
2 ug/m1 » concentration of air pollutants in ambient air in mass
per volume basis; ir.illionths of a gram per cubic meter of air.
3 Class I areas include specified national parks and wilderness
areas. All other areas are currently classified as Class II
areas.
4 The ozone standard is attained when the expected number of days
per calendar year in which the maximum hourly average
more than five TPY of any pollutant. Washington requires permits for all
wood-fired facilities with more than 5 MMBtu/hr input. Vermont has a 90 H.P.
(approximately 10 MMBtu/hr} permit trigger level. A comparison of permit
trigger level among states in the study area is summarized in Table 2-3,
2-10
-------
With the exception of New York State and North Carolina, all of the states in
the study area have been delegated authority to enforce PSD regulations.
Virginia, Washington and Wisconsin use the same definition of "major
stationary source" as EPA for wood-fired facilities, that is, any source with
greater than 2 50 TPY of an attainment pollutant are subject to PSD review,
Connecticut uses a 100 TPY PSD trigger level and Vermont uses a 50 TPY trigger
level. In California, the trigger level for PSD or "major" sources varies by
district. The South Coast Air Quality Management District, for example, uses
a 40 TPY trigger level. PSD trigger levels for states in the study area are
summarized in Table 2-3, It should be noted that permit and PSD trigger
levels may be revised pursuant to the 1990 clean Air Act Amendments,
Table 2-3. Comparison of permit and PSD trigger levels in selected states.
State
Permit
trigger level
PSD trigger level
California
varies by district
in SCAQMD any source
>0
varies by district
in SCAQMD >40 tpy
Connecticut
»5MMBtu/hr
>5 tpy emissions
100 tpy
New Brunswick
>0 (all sources)1
not applicable
New York
>0' {al 1 sources 5
/.u0 tpy (EPA)
North
Carolina
>0 {all sources)
>250 tpy (EPA)
Vermont
wood-fired equipment
>90 hp output
{appro*. 10 MMBtu/hr)
>50 tpy
Virginia
>0 (all sources!
>250 tpy
Washington
>0 {all sources)
>250 tpy
Wisconsin
wood burners > S
MMBtu/hr
>250 tpy
1 Discretionary. Small sources may be exempt.
Compared to state regulations in the U.S., the Province of New Brunswick
(N.B.) has less comprehensive air regulations. The regulations only contain
requirements regarding certificates of approval, smoke density standards and
performance testing and maximum permissible ground level concentrations.
Standards applicable to wood-fired boilers have been established for carbon
monoxide, nitrogen dioxide, sulphur dioxide, and total suspended particulate.
Based on conversations with N.B. regulators, small dedicated wood boilers at
paper mills are exempt from regulation,
2,3.3 Wood Source Considerations
In most states studied for this task, the source of wood fuel has implications
affecting the environmental permitting of facilities. Each state has either
2-11
-------
developed definitions for different wood fuels or classifies facilities
according to the type of wood fuel burned.
Table 2-4 summarizes how the states in the study area define wood or classify
facilities according to the two general definitions presented in Chapter 1:
"clean" wood and "treated" wood. Most states make a distinction between
"clean" and "treated" waste wood in order to impose different permit
requirements. In general, permit review procedures are more difficult and
permit requirements more stringent for facilities burning "treated" wood than
for those burning "clean" wood. Pot example, permits for facilities burning
"treated" wood may require more stringent emission limits, additional ior more
effective) control equipment, .and testing requirements for both fuel quality
and hazardous air pollutant emissions. Only one state, Connecticut, has
prohibited by law (Public Act 90-264i the burning of "treated* wood until the
environmental impacts have been further studied. Most of the other states in
the study area have not permitted such facilities, although there is no law
prohibiting it.
California defines waste wood-fired facilities either as "biomass" or "urban
wood waste" resource recovery facilities. These facilities are therefore
\jsually subject to a similar level of scrutiny as MSW waste incinerators. The
definitions of both "biomass* and "urban wood waste" generally fit within the
definition of "clean* waste wood in this report. Burning wood treated with
paint, resins, glue, etc. has not been permitted to date,- however, based upon
evaluation of data in Chapter 7 as well as observations during the sampling
program, "treated** waste wood is being burned in facilities permitted to burn
"urban waste wood" from demolition activities,
with the exception of California, all the states in the study area classify
"clean" wood-fired energy recovery facilities (for steam and/or electricity
generation) as wood boilers or combustion equipment. In this case, a facility
would be classified as an incinerator only if it was used for volume
reduction. However, the classifications differ in some states where burning
of "treated" wood is concerned, even when energy recovery is included. For
example, New York state classifies waste wood-fired facilities as incinerators
of discreet waste streams if "treated" wood is included. Washington considers
"treated" wood-fired facilities as solid waste incinerators, as does Virginia,
if the facility receives waste wood from off-site sources. In Vermont, there
is no precedent for permitting "treated" waste wood facilities and an
applicant would need to request a declaratory ruling. Wisconsin is the only
state in the study area that does not have a different classification for
"clean" or "treated" waste wood-fired facilities. It is important to note
that the classification of a facility as an incinerator typically has
significant implications in terms of public concern and regulatory scrutiny.
In Hew Brunswick, there is no large scale burning of. "treated" waste wood of
which regulators are aware. However, small quantities of "treated" waste wood
may be mixed with clean hogged fuel and co-fired in wood boilers at pulp
mills. In general, iandfilling "treated" waste wood is the preferred option
at present with only "clean" wood burning encouraged.
2.3.4 Criteria Pollutant Emission Standard*
State emission standards for criteria pollutants are applicable to existing
and new sources. They are not used to set permit limits for new wood-fired
facilities, although they may be used for permitting very small sources not
subject to BACT review. The emission standards are summarized in Table 2-5.
2-12
-------
Table 2-4, Classification of wood-fired facility by fuel type.
State
"Clean* waste wood
"Treated" waste wood
California
"Biomass¦' or "urban
waste wood" resource
recovery facility
"Urban wood waste"
resourcerecovery
facility
Connecticut
"Acceptable wood fuel"
fired boiler
Not currently allowed
by law {under study)
New York
Stationary combustion
installatiOon
Incineration of
discreet waste stream
North Carolina
Clean "unadulterated"
wood boiler
"Adulterated" wood
boiler (incinerator
for volume reduction
only i.e. no energy
recovery)
Vermont
"Natural'1" wood fired
equipment
No precedent -
proposed source should
apply for declaratory
ruling {incineration
for volume reduction
only)
Virginia
Wood fuel burning
equipment
Hot currently allowed
(test burns planned)
burning of waste wood
from off-site sources
classified as
incineration
Washington
Clear wood boiler
{biomass energy
facility)
Solid waste
incinerator
Wisconsin
Wood residue bailer
Wood residue boiler
{same permit
requirements as clean
wood)
New Brunswick
Wood-fired boiler
Mo precedent - treated
wood typically
landfilled
With the exception of California and New Brunswick, standards applicable to
wood-fired facilities have been established only for particulate matter fPM)
and sulfur dioxide (SOj) emissions. Except for very small facilities in some
states, new facilities would be subject to much more stringent permit
limitations as discussed in Section 2.3,5 (BACT). The emission limits listed
in Table 2-5 for California are guidelines (as opposed to regulatory
standards} that have been specifically established for wood-fired facilities
based on operating test data in that state. These guidelines are more typical
of BACT levels. The draft guidelines listed in Table 2-5 for Hew Brunswick
appear to be extremely stringent compared to recent BACT levels from permitted
facilities in the States, especially for carbon monoxide ICO) and nitrogen
dioxide (NO*) .
2-13
-------
Table 2-5. Comparison of state emissions standards (lb/MMBtu)
State
PM
SO,
NO,
CO
HC
California1
0.02
0.0025-
0.025
0.14
0.05-
0.1
0.0006-
.006
Connecticut
0.1
1.0
New Brunswick2
0.2
0.1
0.02
0.1
;. :
New York
0.1-0.6
0.2-
2.5
North Carolina
0.15-
0.7
2.3
—~
Vermont
0.2-0.4
Virginia
0.1-0.6
1.52-
2.64
Washington
0.4
lOOOppm
_
a.
Wisconsin
0.1-0.5
• —-
Blanks indicate no promulgated standards. Federal standards
and/or BACT determined emission limits apply. 1 lb/MMBtu = 429.5
MS/KJ
1 Guidelines, not regulatory standards.
2 Draft guidelines for compliance, air quality regulation 83-
208, lew Brunswick Clean Mr Aet. Also includes stack gas
emission limits for HC1 (0.075) and formaldehyde {0.1).
2.3.5 Best Available Control technology (BACT)
fable 2-6 summarizes BACT trigger levels, limits and controls for the study
area. This information was obtained from draft permits or the most recently
issued final permits obtained from the regulatory agencies. The requirement
to perform BACT determinations varies among the states !and districts in
California). In some districts in California and in New York State, Virginia
and Washington, all sources of air pollution are subject to BACT review. BACT
is required for any pollutant emitted more than 5 TPY in Connecticut and more
than 50 TPY in Vermont. Vermont uses the terminology "most stringent emission
rate". In North Carolina and Wisconsin, BACT is required only for PSD
sources.
Emission limits and controls for particulate matter (PM) are fairly consistent
in the study area for sources subject to BACT. BACT levels typically range
from 0.005 grains/dscf (corrected to 12 percent C02) to 0.02 gr/dscfl. The
most stringent PM permit limits were found in Connecticut and Vermont {0.005
1 1 pound * 7000 grains
2-14
-------
and 0.007 gr/dsc£» respectively}, The least stringent permit levels for PM
were found in recent permits for sources in North Carolina and New York State
{0.02 gr/dscf). Multicyclones followed by high efficiency particulate
controls, electrostatic precipitators (ISPs) or baghouses, are universally
accepted as BACT in the study area. However, interviews with state agencies
indicate that some regulators have personal preferences either for baghouses
or ESPs. Baghouses are believed by some regulators to have better control of
subinicron particulate, while other regulators are concerned with the greater
potential for baghcuse fires.
Most agencies regard selective non-catalytic reduction (SNCR) as BACT for N0X
emissions from wood-fired facilities. The permit limits, however, vary
widely. This seems to be largely a function of boiler type and operating
experience in a particular state. For example, in California, which has the
most operating experience with SNCR, NO, permit levels range from 0.06 to 0.1
lb/MMBtu on recent installations. Most recent wood- or bioavass-fired
facilities in California also use fluidized bed combustors, which inherently
have slightly lower uncontrolled NO* levels than other combuster designs. The
other states, which have less or no experience with SNCR on wood-fired
facilities have higher permit limits, ranging from 0.15 to 0.25 lb/MMBtu. A
recent Vermont permit requires a phased tightening of the emission limit as
operating experience increases, fhe only states that
have not required SNCR on recent large wood-fired facilities are lew York
State, North Carolina, and Wisconsin. Regulators from these states said that
they would be seriously evaluating SNCR on future applications.
With the exception of California, none of the states in the study area is
requiring add-on controls for sulfur oxides (SO,) emissions. Limiting the
allowable sources of wood fuel and the realization that wood has an inherently
low sulfur content are the primary justifications for no controls. In
addition, test data has shown that at least 90 percent of sulfur in wood fuel
remains in the bottom ash due to high alkalinity also in the wood. (Cglesby
and Blosser, 1980}. In California, recent permits for fluid bed boilers have
required limestone injection for additional SOx control. Test data from these
facilities have indicated extremely low SOx emission, even without limestone
injection. ¦
No add-on controls have been required for carbon monoxide (CO) or unburned
hydrocarbon (HC) emissions from wood-fired facilities. Based on discussions
with regulators, add-on controls such as oxidation catalysts do not appear to
be technically feasible, cost effective, or warranted at this time. In most
states, permit limits for CO range from 0.3 to 0.6 lb/MMBtu (approximately 250
to 500 ppmvd) and "good" combustion design or control is specified as BACT.
The exception again is in California, where most of the recent wood or biomass
facilities have required fluidized bed combustors. Although these boiler
designs typically emit comparatively low levels of CO and HC {less than 10
ppmv for both CO and HC and often less than 1 pprav!, operating experience has
shown much lower availability and higher maintenance requirements and
installed costs than more conventional wood-fired boilers such as spreader
stokers. In Wisconsin, permits typically do not contain limits for NQX, CO
and HC emissions. Instead, "good combustion technology" is specified. The
minimum requirements include a 1250°F boiler exit temperature, 1 second
residence time, and maximum 500 pprav CO concentration.
The Province of New Brunswick does not have formal BACT requirements similar
to EPA or state requirements. Instead, emission controls are reviewed on a
case-by-case basis. Until recently, installations of industrial-sized wood
boilers usually only required controls on PM. Typical controls include
multicyclon«s and ESPs with relatively high emissions limits (0.1 gr/dscf).
However, in September, 1991, Environment Hew Brunswick issued draft Guidelines
2-15
-------
for compliance under the Air Quality Regulation 83-208 (Clean Environment Act)
for wood-waste boilers in the 3 to 10 rrrw size range. The draft guidelines
recommend stack emission limits for all criteria pollutants in addition to
hydrogen chloride and formaldehyde. The guidelines are especially stringent,
for CO and NGX compared to recent state BACT determinations.
2,3.6 Nonattainment R«view
While the nonattainment provisions of the 1990 Clean Air Act Amendments (1990
CAAA} are not yet in effect, even the largest wood-fired facilities (from 3 to
50 MW depending on combustor design) in most states do not typically trigger
review under nonattainment regulations of the old Clean Air Act. Ozone, for
which HC emissions are considered the major precursors under the old Clean Air
Act, is the pollutant that most often is nonattainment. Wood-fired facilities
are typically not "major" emitters of HC emissions by the various states'
def initions (usually SO to 100 TPY)and therefore, do not trigger
nonattainment requirements for lowest achievable emission rates (LAER5 and
emission offsets. Again, California is the exception, by requiring LAER and
offsets for any emission increases of ozone precursors in some districts and
relatively minor emission increases in others.
A significant consideration for wood-fired facilities in the future, when
regulations are promulgated under the 1990 CAAA, (by November, 19921, is that
LAER and emission offset requirement© will be mandatory in. many other areas
including California. The trigger levels for nonattainment requirements will
vary depending on the severity of nonattainment in a particular region. The
definition of a "major" source of nonattainment pollutants will vary from 10
TPY {in areas such as southern California) to 2S-50 TPY {for the northeast).
Moreover, regulation of ozone precursors will be expanded to include both N0X
and HC,
California currently has an emission offset program that allows emissions from
biomass resource recovery facilities to be offset based on the emission
benefits that occur when biomass that would have normally been disposed of by
open burning is used as fuel in an incinerator equipped with emission
controls. The applicability of this program may be unique to California,
which has a huge agricultural valley and associated biomass generation rate.
There are no non-attainment provisions in the regulations for the Province of
New Brunswick,
2.3.1* Hazardous Mr Pollutants
Hazardous air pollutants (HAPs) usually associated with wood-fired facilities
include benzene, formaldehyde, acetaldehyde, trace metals, and with less
probability (based on available test data!, polynuclear aromatic hydrocarbons,
chlorinated dioxins, and furans. All of these compounds are regulated in each
of the states in the study area. Draft guidelines have been issued to
regulate stack amissions of formaldehyde from wood boilers in New Brunswick,
Canada. Table 2-7 compares the requirements for HAP emissions in the study
area. The similarity in state requirements and the fact that all states go
well beyond the federal NESHAPS regulations are evident from this comparison.
Each state has established acceptable ambient air concentrations that are, for
the majority of chemicals, based on occupational exposure limits with health-
protective factors applied. These safety factors and the names assigned to
the ambient concentrations vary among the states. In addition, California and
New York use compound-specific toxicity studies and other sources in addition
to occupational exposure limits to develop some of the acceptable ambient
concentrations.The other major similarity in the HAP requirements is that all
states require some level of dispersion modeling or dispersion-based
2-16
-------
Table 2-6, Typical BACT levels based on recent permits {mid-1992).
m.
HOi
SO.
OD
HC 1
state
BACT
trioqer level
limits,
gr/dscf
controls
limits
Ub/MKBtu
controls
limit©
(Ib/MMBtu)
controls
limits
Ub/MMBtul
controls
limits
1 Ib/MMBtu}
controls
California
0=250 lb/day
0.01
irul' n I ones fa
nw ox
l*ayh< r&c
006-0.1
SNCR'
0.0004'0-04
fuel control.
limeatone
injection
0,0210,IS
fluid b«d
combustion
design
0001-0.03
fluid bed
combust ion
dea i250 TPY
0,02
multiclon®® ~
ESP
0,35
combustion
control
—
0.66
combust1on
desiqn
0.07
coofoust ion
design
Verroont
>50 TPY IMSERi
0.00?
BUlticlonea *
ESP
0,15-0-25
SNCR
0.07% 5
content
fuel control
0.3
cowbtfstion
design
—
—
Virginia
ill sources
1 large boiler}
{small boilerI
001
0,1
awltlclon*a *
SSP
0.15
SNCR
combustion
control
0.02
0.02
Cu»l control
fuel control
0.5
o.s
combustion
design
couib^js t ion
design
0.3
0.2
combus t ion
design
design
Washington'
all sources
0,01
ran 1U c1onea &
SSP oi
Uiqhouoe
—
SMCR
--
fuel control
—
cctabufUon
design
—
costbusfcioo
deBign
Wisconsin
>«0 TPY
o.ei
nulticlonee 4
fc&ghoase
—
•good
combustion
control"*
—
—
'good
combustion
control*
—
"good I
combustion 1
control' |
Footnotes:
1. corrected to 12% C02j 1 gr/dscf - 2.2 Ib/MMBtu.
2. no recent permits.
3. SNCR. = selective non-catalytic reduction.
4. means >1250° F exit temperature, >1 second residence time, <550 ppro CO.
-------
calculation procedure to evaluate compliance with the regulations. Dispersion
modeling (screening level or refined analyses) are required in all states in
the study area except Connecticut and Vermont, In Vermont, modeling is
optional and up to the discretion of the agency. In Connecticut, the
dispersion equation has been solved for an assumed set of conservative
meteorological inputs and a maximum allowable stack concentration is
back-calculated for compliance demonstration purposes. The calculation
procedure is a function of stack height, gas volume rate, and distance from
stack to property line.
Application of BACT or LAER is mandatory only in Vermont, Virginia and
Wisconsin if HAPs are emitted at rates above compound-specific action levels.
In all other states in the study area, BACT would be required only if
compliance with acceptable ambient concentrations could not be demonstrated
with dispersion modeling.
Tabl62^Cmgari|on^r^m^wtsfOThaz^&usairplMMts.
atata/provanca
snarsdatery health
risk assessment
for carcinogens
Acceptable anteiant
concentrations
(ACC) based on
occupational
•xposura liauta
diap«r»ioa
modeling to
evaluate
coctf>li«ac« with
ACC
BACT or LASH [
California
Yaa
*•»
tm»
Yaa! 1
Connecticut
No
Yaa
Ym»*
Yaa'
Mew York
Mo
Yaa
Ya>
Yess
North Carolina
Mo
Yes
Yaa
Ya»!
Vanaont
No
Yaa
Ya»>
Yes*
Virginia
Mo
Yes
¥••
Yaa*
Washington
les*
Yaa
Yaa
Yes1
Wiaconain
No
Yaa
Ih
Yes*
Mew Brunavick'
Nc
Mo
Mo
No
Footnotes: •
1. Only if required to demonstrate compliance.
2. Back calculation of maximum allowable stack concentration based on
ACC.
3. At discretion of agency.
4. Mandatory if action levels (ACCs) exceeded,
5. If required to meet ACCs.
6. Regulates stack emissions instead of ambient concentrations.
Guidelines for preparing health risk assessments for carcinogens have been
published only in California. Although there is no automatic requirement to
prepare a cancer risk assessment, wood-fired facilities in California are
classified as resource recovery facilities with the connotation of
incinerators. Large facilities being permitted in the state typically require
risk, assessments as part of the review process under the California
Environmental Quality Act.
In Connecticut, the potential for cancer and acute non-cancer risks became ail
issue in recent public hearings for a 'clean* waste wood-fired boiler. The
state agency maintained that its HAP program was sufficiently health
2-18
-------
protective and that no further analyses were necessary if the applicant was
able to comply with the program. However, the state Attorney General's
office, acting in the interest of the public, requested that a targeted health
risk analysis be performed for the proposed facility. The analyses
demonstrated that the state agency's HAP program was sufficiently health
protective.
Air toxics are not formally regulated in the Province of New Brunswick,
although draft guidelines recommending stack emission limits have recently
been issued for hydrochloric acid and formaldehyde emissions from, wood
boilers. In addition. Environment Canada is developing lists of priority
substances and source categories. Regulation of hazardous air pollutants is
imminent in the provinces. The likely pollutants of concern from wood burners
are formaldehyde and PAH,
2,3,8 Regulatory Climate/Additional Requirements
To evaluate the regulatory climate for obtaining permits for "clean" and
"treated* waste wood-fired facilities, regulatory agencies were contacted to
answer the following questions:
• How many facilities are operating/permitted in the state?
• How many recent permits have been issued?
• Do any burn or plan to burn "treated* wood waste?
• What has been the public acceptance of "clean"/"treated" waste
wood-fired facilities?
• Has there been much public intervention or hearings?
• To what extent do new facility permits require stack emissions testing
{for criteria and noncriteria pollutants), fuel testing, ash testing,
and continuous emission monitoring (CEM) equipment?
fable 2-8 summarizes answers to these questions. Several of the states,
including California, North Carolina, Virginia, Washington and Wisconsin have
many small "clean" wood-fired facilities operating at sawmills, paper mills,
and furniture manufacturers. Most of these facilities have with small
antiquated boilers. California has approximately 70 "biomass" and/or "urban
wood waste" fired resource recovery facilities generating electricity for sale
to local utilities. These facilities have typically been encouraged in
California as a means to provide incentives to minimize open burning of
agricultural (biomass) waste. Other states, including Hew York, North
Carolina, Virginia, Washington, Vermont and Connecticut have fewer facilities
operating, under construction or in the permitting stage. Connecticut is the
only state in the study group that does not currently have a wood-fired
electric generating plant. Two facilities have been in the permitting stage
for more than four years and were recently bought out by the power utility for
eighteen million dollars to prevent their construction. New Brunswick, Canada
has approximately 12 wood boilers operating at pulp and saw mills.
The only states in the study area that have permitted facilities to burn
"treated" wood are Virginia and Wisconsin. The Koppers facility in Roanoke,
Virginia does not strictly burn "treated" wood. Rather, it has been permitted
to burn a mixture of "clean™ wood with a waste creosote/coal tar sludge from a
railroad tie manufacturing plant. The facility has been tested and has
demonstrated compliance with its 99.9 percent creosote destruction and PM
emission limits. An older Northern State Power plant in Wisconsin is the only
2-19
-------
other facility located in the study area that is permitted to burn "treated"
waste wood (railroad ties). toother Hoppers facility outside the study area
{in Pennsylvania) was identified as a railroad tie burner.
Although "treated" wood combustion has been permitted in Virginia and
Wisconsin, it may not be appropriate to characterize other small manufacturing
boilers as "clean" wood-fired facilities. Many of these facilities burn
treated mill residue such as plywood, OSB or particleboard trim as a
substantial portion of their feedstock. The concern is magnified by the fact
that many of these are antiquated boilers that may have little if any
combustion or stack controls.
There is also an important regulatory issue brewing in several states such as
Wisconsin, Virginia and North Carolina that have many small wood manufacturing
boilers. These state agencies are attempting to find out how "clean" these
manufacturing boilers are and, if necessary, upgrade permit requirements and
stack controls for previously grandfathered or exempt systems. A statewide
testing program in Wisconsin of small boilers is an example.
There has been interest for wood-fired facilities to burn scraps of plywood
and particle board. Wood makes up from 8 5 percent to 95 percent of these
products and the urea formaldehyde and phenol formaldehyde adhesives, which
make up the remainder, are composed entirely of molecules of carbon, hydrogen,
oxygen, and nitrogen atoms. Nevertheless, burning plywood and particle board
scraps has been specifically excluded from these facilities' allowable fuel
sources. One facility in Virginia has as a permit condition the provision to
conduct a test burn of plywood scraps. Based on the results of emission tests
conducted during this test burn, the facility may conditionally be allowed to
burn plywood scraps.
With the exception of Connecticut, "clean" wood-fired facilities have been,
able to gain public acceptance. In Connecticut, two "clean" wood facilities,
that originally proposed to burn "treated" wood, have been mired in the permit
review process for wore than four years. Due to public scrutiny, a law was
passed to prevent "treated" and demolition wood as an acceptable fuel source
and permit conditions that were originally written for burning "treated" wood
have remained in the draft permits even for "clean" wood. These permit
conditions include extensive stack testing of noncriteria pollutants in
addition to all criteria pollutants. Stack testing will be required for
fifteen trace metals and more than ten organics, including benzene, aldehydes,
PAKs, dioxins and others that are not expected to be present in detectable
concentrations. Public hearings for one of these facilities set a record in
the state for number of days. In most other states in the study area, public
opposition is expected to be heightened for facilities proposing to burn
"treated" waste wood.
All states in the study area require stack compliance testing for most of the
criteria pollutants. Fox larger facilities subject to federal NSPS
requirements, compliance testing is mandatory for PM, S0X, NOx and CO.
California and Connecticut also require stack testing for HC emissions. Other
states require testing of fewer criteria pollutants for smaller facilities.
All states and New Brunswick have required at least PM testing on all
facilities. Of the states in the study area, testing of noncriteria
pollutants has only been required in California, Connecticut and to a lesser
extent in Wisconsin. The most extensive requirements, as mentioned
previously, have been for the proposed plants in Connecticut. California is
the only state in the study area for which extensive testing has been
performed to date. The California Air Resources Board !CARB} has tested at
least four "biomass" and one "urban waste wood" facilities for metals, PAls
and other aromatics, benzene, chlorinated phenols and aromatics, PCBs,
2-20
-------
Table 2-8. Comparison of regulatory climate/additional requirements.
state/ province
erf iirwtc nurni
o? permt r tivi > >r
.% *-reUirj
facili^icfcs1
number of
recent
permits®
tpinfcoir fit
p-Htn-ito tor
" tiuai f-d*
w^-'d
public acceptance
public hearings
emission resting required
fuel
testing
ash testing
CEKS |
criteria
non criteria
Calif oxm&
70
10
0
good
Yes
PHfHC»|40c,CQrS0x
rppiesenrg-tivo
girrv.ip tofieJ f -r
ir.CtdliK, bCr.Zi.CH
PAH iioxir.s
etc
Yes
Yes
Opacity, D
co, mr I
Connecticut
S
2 draft
permits
0
very low even for
•clean* wood
Yes
PM.HC.MCV-CO.SOj
fcr %-lean" wood:
J9 KAi-a including
neliils, i'AH,
.itoxins, t«nzetie,
a Ideftydea,
chloj- mat ed hc .
Yes tor
•clean'
wood -
metals
Yes Cor
•clean*
wood -
metals
Opacity,
co, m.
Now Brunswick
12
%
0
aocd
N©
F*LHC.WG)t,CO,SG,
HCi. fornaldehyde
Mo
No
Opacity
New YorJc
%
I
0
good
No (optional)
PM,HC,JKVOO,$32
if >103
MMStu/hi, m if
*ia km
Yes Cor "treated*
wood
Yes for
'treated*
wod
Ye* for
* treated*
wood
Opacity,
CO, NO.
•North Carolina
2
i
7
opposition expected
Cor 'treated- wood
opt lor&al
m
Yes tor 'treated"
vood
Yes tor
-treated'
wood
Yes Eos
¦ \ r*-«t ed'
wood
.opacity
Vermont
2
a
0
opposition expected
tor * treated* wood
Y&a, mandatory
for >50 TPY
Yes for 'treated*
wood
Yes for
"treated4
wood
Yes for
•treated*
wood
Opacity.
CO. ^
Virginia
3
4
I
opposition for
*t:f»ata-r wj;d
Sf »te law
Facilities will not
t/p revtuwevl withcur
lov'&l support
Yes (tor major
sources, optional
tor others)
PH.MO,
Yes for phenol#
and formaldehyde
Yes
Yes
opacity
Washington
3(>50KW)
ISO email
"clean'wood
boilers
0
0
good
No (optional)
PK,COJHCfNO«
l«nnualiy)
Ye# for "treated*
WOOd
isaytoe for
"treated"
««©d
mytem for
'treated*
wood
Opacity,
CD
Wisconsin
2
?
I
good
No (optional)
forvAldehyde,
metals (annually)
maybe for
•treated*
wood
maybe for
'treated*
wood
opacity, 1
CO |
Footnotes;
1. All waste wood burning facilities, "clean" and "treated* wood.
2. Last 3 years.
-------
Dioxins, and furans. The Timber Association of California has also pooled its
resources in response to an MAP testing requirement to test a representative
sample of wood boilers. These data are summarized in Chapter 8,0 in addition
to data from other reports of noncriteria emission tests. According to draft
guidelines applicable to wood boilers, additional facilities in New Brunswick
will require testing for criteria pollutant emissions, hydrochloric acid and
formaldehyde.
The only state in the study area that requires both fuel and ash sampling for
"clean" wood-fired facilities is Connecticut, As discussed previously, this
requirement is on draft permits that carried over conditions that were
originally part of a proposal to burn "treated" wood. Based on telephone
interviews, regulators from New York and Wisconsin indicated that fuel and ash
testing may be required for "treated" waste wood-fired facilities.
Continuous emission monitoring (CEM) requirements for all states are at a
minimum, in conformance with NSPS requirements. NSPS require opacity, CO, and
NOx CEMs depending on the size of the facility. Connecticut will also require
S02 monitoring and may require a CEM for hydrogen chloride. New Brunswick
only requires CEMs for opaci ty.
2.4 Fadaral Solid Waste Regulations
This section provides an overview of federal solid waste regulations that
potentially affect facilities that combust waste wood for fuel. Information
on, current regulations and policies in each state and province in the study
area is presented in Appendix B.
Federal solid waste regulations that potentially apply to new and modified
waste wood combustion facilities are contained in the Resource Conservation
and Recovery Act (RCRA) of 1976 (42 USC 6901 at seq.) and the Hazardous and
Solid Waste Amendments of 1984. The 1984 legislation amended the original
RCRA statute in several key areas.
Similar to air pollution regulations, the Environmental Protection Agency
delegates authority to states for administering provisions of RCRA where state
programs meet or exceed federal standards. In addition the state program must
be implemented in accordance with guidelines set by EPA in order to keep its
administration of the program. Each state in the study area has complied
with, or exceeded RCRA regulations that were initiated in 1980. Therefore,
regulatory activity concerning solid waste management and disposal occurs
primarily at the state or local level.
2.4.1 USEPA Definition* of Solid and Hazardous Waste
According to RCRA, a solid waste is "..any discarded material... which
is...abandoned,...recycled,...and inherently wastelike..." regardless of
whether the material is accumulated, stored, reused, reclaimed, recycled,'
burned or incinerated, or disposed of. The definition of solid waste applies
to "garbag®, refuse, or sludge; solid, liquid, semi-solid or contained gaseous
material* including by-products from manufacturing industries,
¦Also according to RCRA, a solid waste is a hazardous waste if it exhibits
characteristics of hazardous waste identified in Subpart C and Subpart D of
the Act, and if it is not purposefully exempted from regulation as a hazardous
waste under one or more "exclusions" as defined in Subpart A.
If there is uncertainty about the composition of the feedstock used or ash
produced by a facility, a waste characterization and testing process is
required to determine whether the material exceeds concentrations for key
2-22
-------
inorganic and complex organic constituents. The characterization process for
determining whether a material should be managed as a solid or hazardous waste
is described in Title 40, Code of Federal Regulations under:
• Subpart A, Section 261.2, Definition of a Solid Waste;
• Subpart A, Section 261.3, Definition of a Hazardous Waste;
• Subpart A, Section 261.4, Exclusions,* and
• Subpart C, Section 261.22 and 261.24 that describes Characteristics of
Hazardous Waste.
Subpart C evaluates waste based on characteristics of ignitability,
corrosivity, reactivity, and toxicity. If waste wood feedstock is determined
to be hazardous, then it must be handled in a designated hazardous waste
facility and is beyond the scope of this study. Only corrosivity and toxicity
characteristics are relevant to waste wood ash, since the material is neither
ignitable nor explosive. Corrosivity is determined by measuring the pH value
of material.
The RCRA standard for corrosivity is whether the material is "... aqueous and
has a pH value less than or equal to 2 or greater than or equal to 12.5...*
In most states, only the corrosivity of aqueous ash leachate is measured.
However, one state, Washington, has adopted a 12.5 pH corrosivity standard
that is used for ash in its solid form, as well. Ash from the combustion of
clean wood and treated wood has typical pH values from 8 to 13 {Campbell,
1990).
Two tests have been developed to simulate the leaching characteristics of ash
or any material containing hazardous contaminants. The Extraction Procedure
Toxicity Characteristic Test, the EP fox Test, is the older test method, and
has been criticized for lack of reliability and consistency. In 1990, EPA
adopted a more expansive extraction test, the Toxic Characteristic Leaching
Procedure (TCLP} test, now the test method that must be used for regulatory
purposes. TCLP is more stringent than the EP Tox Test due to the increased
number of organic constituents [such as pentachlorophenol and cresols)
requiring testing, and to the sensitivity of the test method used. However,
TCLP has also been criticized for its cost and inconsistent sampling procedure
(Rogoff, 1991).
The toxicity test in section 261.24 of RCRA establishes the TCLP test methods
and concentration levels for potential hazardous wastes.
Selected levels for toxicity characterizations that nay affect the
classification of ash from waste wood combustion are listed in Table 2-9.
2.4.2 Exclusions under RCRA
Subpart A, Section 261.4 of RCRA contains key "exclusions" or exemptions for
wastes that might otherwise be designated as hazardous. There are two
exclusions among a list of ten that potentially apply to waste wood combustion
facilities. These exemptions prevent facilities that combust certain types of
waste wood from being categorically defined as facilities that combust
feedstock or produce hazardous ash.
The first pertains to the "household exclusion" for MSW facilities. This
provision states that *...A resource recovery facility managing municipal
solid waste shall not be deemed to be treating, storing, disposing of, or
otherwise managing hazardous wastes for the purposes of regulation [under
2-23
-------
Table 2-9. Selected threshold concentrations for toxicity characteristics
under RCRA1
Contaminant
Regulatory level, mg/1 |
Arsenic
5.0
Barium
100.0
Cadmium
1.0
Chromium
5.0
Cresol
200.0
Lead
i .
Lindane
0,4
Mercury
0.2
Pentachlorophenol
100.0
Selenium
1.0
Silver
Footnotes;
1. Excerpted from "Table 1. Maximum concentration of contaminants
for the toxicity characteristics" in 40 CPR, Section 261.24. This
standard is applicable to any waste containing potentially toxic
characteristics.
2. mg/1 = milligrams per liter.
federal hazardous waste rules]..." provided that the facility receives and
burns only:
• "household waste";
• "solid waste from commercial or industrial sources that does not contain
hazardous waste"; and
• that; facility operators establish "...contractual requirements or other .
appropriate notification or inspection procedures to assure that
hazardous wastes are not burned in such facility,"
This section of RCRA has generated considerable controversy, particularly
amendments to the 1990 Clean Air Act. Some claim that ash residue from
municipal solid waste facilities should not be exempt from federal hazardous
waste rules. The 1990 Clean Mr bill avoids a position on this question and
defers to RCRA reauthorization legislation that is expected to be acted on in
1992. This could affect the federal and state environmental review and
permitting of waste wood combustion facilities.
The second exclusion applicable to potential waste wood combustion facilities
pertains to certain types of treated waste wood. Under RCRA, a solid waste is
also defined as non-hazardous if the waste "...consists of wood or wood
products which fails the test for the Toxicity Characteristic solely for
arsenic and which is not a hazardous waste for any other reason or reasons, if
2-24
-------
the waste is generated by persons who utilize the arsenical-treated wood and
wood products for these materials' intended use."
Some states, such as Mew York, have accepted both these federal exclusions as
part of their solid waste program. New York emphasizes, however, that
regulators will closely review wood fuel agreements between, fuel suppliers and
combustion facilities for guarantees that the facility will not accept or burn
hazardous waste. If contractual guarantees on fuel quality cannot be
verified, then New York reserves the right to require fuel and/or ash
characterization and testing.
2.4.3, Ash Disposal Regulation*
The primary solid waste management concern with respect to waste wood
combustion facilities is ash characterization and disposal. Ash management is
the focus of the solid waste regulatory discussion in the overview of state
solid waste regulations in Section 2-5 and in each of the state descriptions
included in Appendix B.
Approximately 20 to 25 percent of the total weight of waste burned in
mixed-waste MSW facilities is produced as ash residue {Hauser, 1991) .
Approximately 1 to 3 percent of the total weight of wood burned in waste wood
combustion facilities is produced as ash residue (Campbell, 1990}. Therefore,
smaller quantities of metal contaminants in wood than in municipal solid waste
could result in much higher metals concentrations in the wood ash than in
municipal solid waste ash due to the lower level of dilution resulting in wood
ash than solid waste ash. The overriding concerns about disposal of any ash
is the potential for the material to leach heavy metals and other
contaminants, and the potential for contaminants in the leachate to enter
ground or surface waters.
It is important to note that tests done to date of ash from full-scale
operating facilities burning "clean* waste wood and ash from "treated" waste
wood combustion do not demonstrate a clear tendency to .exceed federal toxicity
or corrosivity standards. However, test methods and standards in some states
are more stringent than federal standards, for some ash characteristics.
2.4,4 USEP& Solid Waste Regulatory Trends
There are several solid waste regulatory issues at the federal level that may
affect the permitting of facilities that combust waste wood in the future such
as the anticipated reauthorization and amendment of RCRA in 1992, and recent
EPA proposed rulemakings on land disposal of contaminated debris. The issues
noted below were discussed in 1990 and 1991 during initial RCRA
reauthorization hearings and EPA rulemaking efforts.
to important question expected to be addressed at the federal level is if ash
from MSW combustion is categorically defined as a hazardous waste, and this is
not likely to occur, then it could prompt federal and state regulators to
define ash from certain types of waste wood combustion as hazardous. If this
occurs, it would significantly change the regulatory review, characterization,
testing, and permitting procedure for most wood-fired facilities, particularly
those that currently burn or intend to burn "treated" waste wood. It is
likely to i ncrease the length of time and expense involved in permitting and
operating a facility. However, waste characterization and testing procedures
are currently required for all MSW ash and, to a lesser extent, ash from wood-
burning facilities.
A second issue likely to be raised in RCRA reauthorization is establishment
of a national recycling goal of 25 percent {or some other target recycling
2-25
-------
rate) as a prerequisite for permitting MSW combustion facilities. The 25
percent goal was proposed daring rulemaking in 1990 and subsequently rescinded
by EPA {Fields, 1991). The establishment of a target recycling rate for MSW
combustion, facilities will in turn result in a discussion and listing of which
materials are recyclable; whether burning waste wood for fuel counts towards
recycling goals; and whether MSW facilities that burn waste wood will have to
dedicate a portion of the available feedstock to alternative end uses to meet
recycling quotas,
A third issue concerns the effect of a new rule proposed by EPA in May, 1991
under 40 CFR, Part 268. The rule may enhance the recoverability of waste wood
for energy. Among other issues, the rule addresses development of a Best
Demonstrated Available Technology (BDAT) standard for certain types of
"contaminated debris," EPA has proposed "eight preliminary subcategories of
debris that may pose different probierne in treatment." One of the categories
is wood. Other categories include brick, concrete, rubber, and plastic. The
significance of the rule to waste wood combustion is that EPA, in explaining a
rationale for a potential BDAT standard for contaminated debris, has
emphasized that certain materials such as "contaminated" wood, may best be
handled through combustion technologies:
"...The treatability of debris is also affected by the
physical and chemical characteristics of the chemical
contaminants on the debris, and their respective
concentrations. For example, it may be reasonable to
incinerate a debris material contaminated with high
concentrations of toxic organic* and low concentrations of
metals..." (Federal Register, May 30, 1991, Vol. 56, So 104, p.
24457),
2.4,5 Federal Solid Waste Guidelines in Canada
The Canadian federal government does not publish solid waste regulations
specific for the combustion of waste wood or other forms of: solid waste.
Regulatory jurisdiction is left primarily to the provinces. Guidelines for
the operation of municipal waste incineration have been published, however, by
an interprovincial task force under the Canadian Council of Resource and
Environmental Ministers (CCREM). The province of New Brunswick has published
site and design requirements for landfills but does not require, for example,
a hazardous waste characterization of waste wood ash or feedstock.
Environmental standards for combustion systems in New Brunswick ana other
provinces are addressed primarily through air regulatory controls. The
province of Ontario has proposed air quality rules specific to waste wood
combustion that, include requirements for ash testing under a leachate
extraction procedure test. The test is detailed in the provincial
Environmental Protection Act, Schedule 4,* however, these rules have not been
adopted to date.
While the CCREM guidelines may end up as a reference for how ash disposal from
"treated" waste wood combustion is reviewed in New Brunswick in the future,
they may not be appropriate for ash from waste wood combustion facilities. In
a section on ash management, the CCREM guidelines recommend (generally) that
ash should be tested for physical and chemical characteristics, be quenched to
prevent fugitive emissions, and that bottom ash should be treated and disposed
of separately.
With respect to hazardous waste determinations, the Canadian government has
established a law entitled "Transportation of Dangerous Goods Regulation"
under its federal transportation authority, that pertains to the transport of
hazardous materials. The law does not have direct regulatory authority for
2-26
-------
ash management from combustion; however, some provincial officials use this
law as guidance when making determinations about proper disposal for
substances believed to have toxic characteristics (Godin, 1991), Most
threshold toxicity concentrations under this law are similar to standards in
the U.S. EPA's TCLP procedure and are noted in the discussion of state and
provincial solid waste regulations in Section 2.5.
2,5 State/Provincial Solid Waste Regulations
This section discussed state or provincial solid waste management, permitting,
and regulatory issues affecting waste wood facilities in the study area. This
discussion addresses both waste wood processing and combustion facilities.
As noted in Section 2.4, solid waste regulations in each state in the study
area have met or exceeded standards required by the Federal Resource
Conservation and Recovery Act, therefore, the waste management, permitting,
and enforcement responsibilities have been delegated to the states. In
Canada, solid waste management is essentially under provincial jurisdiction,
although guidelines have been developed at the federal level for MSW
combustion. The Province of New Brunswick relies on landfills for waste
disposal; their solid waste strategy is based on landfill design and
management standards.
In addition, six states in the study area have developed hazardous waste
regulations in addition to federal rules. The states include California,
Connecticut, North Carolina, Virginia, Vermont, and Washington. With the
exception of California, the rules tend to be only slight modification to the
overall approach established in RCRA. The Province of New Brunswick had not
established specific hazardous waste regulations and relies, instead, on
consultation with and guidelines promulgated by the federal government in
Canada, which governs the transportation of hazardous substances.
A variety of state and provincial solid waste management, permitting, and
regulatory issues affect the regulatory review and permitting of waste wood
processing and combustion facilities. Key issues and their significance are
summarized below. A summary of solid waste regulatory strategies in the study
area is presented in Table 2-10.
2.5.1 Regulatory Definitions of "Clean" and -Treated" Waste Wood
The first issue is whether there are regulatory definitions under solid waste
rules that distinguish "clean" waste wood from "treated* waste wood, and what
the definitions are. If there are no definitions, it may be unclear how to
review and permit a waste wood processing or combustion facility.
In the study area, there are definitions for "clean" waste wood in all states,
except California and New Brunswick. Specific language and definitions used
to describe "clean* waste wood as defined in this report vary widely. For
example, the terms harvested, virgin, yard, or untreated waste wood may be
used to define and describe "clean" waste wood. Some states indirectly define
"clean" waste wood by specifically defining what is not clean, such as wood
from demolition activities. One state, California, uses a broad definition of
wood waste that includes wood generated from the manufacturing, harvesting,
processing, or storage of wood materials, or construction and demolition
sources. Overall, however, the states tend to consider harvested wood, yard
waste, some or all pallets, and mill residue burned on-site for fuel as
"clean" wood fuel.
Currently, four states, Connecticut, New York, Vermont, and Washington, have
specific regulatory definitions for "treated* waste wood as defined in this
2-27
-------
Table 2-10. Summary of solid waste management strategies in the study area
affecting waste wood combustion and ash disposal1.
Solid Waste Regulatory Policy
CA
CT
NC
NY
VT
VA
WA
WI
NB
(CAN)
a. Regulatory definition for
Y
Y
Y
Y
Y
Y
Y
"clean" waste wood.
b. Regulatory definition for
Y
Y
Y
Y
"treated" waste wood.
c. Regulatory definition of
Y
Y
Y
Y
Y
Y
Y
Y
construction or demolition
debris that includes waste
wood.
d. Energy recovery of treated wood
Y
Y
Y
Y
Y
Y
Y
Y
specifically defined to not be
a "recycling" activity'.
e. State has recycling targets
Y
Y
Y
Y
Y
?
?
that discourage waste wood
from being landfilled}.
f. Solid waste regulators classify
"clean" waste wood combustion
for energy as4:
Incineration
Energy/resource recovery
Y
Y
Y
Y
Y
Y
Wood residue combustion
Y
Y
Y
g. Solid waste regulators classify
"treated" waste wood combust ion
for energy as*:
Incineration
Y
Y
Y
Y
Y
?
Energy/resource recovery
Y
Y
Y
Wood residue combustion
h. Waste characterization of
Y
?
Y
Y
Y
?
Y
feedstock required for
"treated* waste wood
combustion*.
i. Ash from waste wood combustion
classified as':
Solid waste
Y
Y
Y
Y
Y
Y
Y
Special waste
Y
Other waste residue
Y
j. Ash management plan required.
?
Y
Y
Y
Y
Y
k. Waste characterization of ash
Y
Y
Y
Y
Y
Y
Y
Y
¦»
from "treated" waste wood
combustion required7.
1. Non-hazardous "treated" wood
combustion ash to be disposed
of in s
Lined landfill
Y
Y
Y
Y
Y
Unlined landfill
Y
Lined monofill or monocell
Y
Y
Y
Y
Y
Y
On-site monofill at the
Y
Y
Y
Y
y
facility
m. Alternative utilization
Y
Y
Y
Y
Y
Y
standards for ash disposal*.
Footnotes;
1 A "Y* indicates this regulatory strategy is in effect at the state or
2-28
-------
Table 2-10 concluded.
province noted. A blank indicates the strategy is not in effect. A
indicates that the state/province strategy is uncertain, based on a review
of written documents and telephone interviews with regulatory officials.
2 Although most states do not view energy recovery of waste wood as
consistent with state recycling goals, conversations with state regulators
indicate interest in further defining certain combustion activities as
compatible with "reuse" goals and as preferable to mixed MSW incineration.
3 Several states are in the process of restricting the land disposal of waste
wood as part of'their efforts to meet statewide recycling targets. Some
sates, such as Virginia, note that "clean" wood is a recyclable material
while •treated" wood is not. In other states, such as California, all
waste wood types are included. Overall, the trend points to an increasing
need tor additional reuse, recycling, or disposal options for waste wood.
4 Solid waste regulatory definitions about facility classifications vary
among states/provinces. In California, for example, any combustion
facility, whether burning for volume reduction or energy recovery, is
termed a "transformation" facility. similarly, in Vermont, combustion
facilities are termed "treatment facilities." This table shows the general
regulatory approach taken by each state/province although the exact
classification may differ.
5 In many states, feedstock characterization will be required under both
solid waste and air quality regulations while other states, such as
California, rely on fuel testing as part of the air quality review only.
6 In some states, such as Connecticut and New York, fly ash may be managed
differently from bottom ash for disposal. Fly ash typically contains
higher concentrations of metals and organies than either bottom or combined
ash.
7 States do- not specify "treated" wood combustion as being subject to
toxicity waste characterization in their rules. States typically have
authority, however, to require ash testing under state law or 1CEA, if ash
contents are uncertain or if data are unavailable on ash or fuel contents.
8 In many states, there is a regulatory procedure for demonstrating that ash
or other wastes have alternative "beneficial uses" versus landfilling (such
as landspreading, soil amendment or additive to concrete}. This process
may require ash testing and a petition for a variance to landfilling.
report. The definitions distinguish between "clean" and "treated" waste wood;
however, the specific language varies. For example, the terms adulterated,
urban, and demolition waste wood may be used to describe "treated" wood. The
states generally tend to consider painted or stained wood, wood containing
glues or resins, wood from demolition sources, and wood treated with
preservatives or other materials as "treated", and therefore, potentially
subject to regulatory scrutiny.
2.5.2 Regulations or Policies on C/D Waste Wood
A second issue is whether there are regulations or policies for the management
and disposal of construction and demolition waste, and whether wood is
specified. If there are C/D regulations or policies and they specifically
2-29
-------
address'wood, this can affect the review and permitting of processing and
combustion facilities that receive C/D waste wood.
Presently# all of the study area, except New Brunswick, has regulations or
policies that define C/D waste. Most of the regulations specifically mention
wood as a type of C/D waste. For example, New York and Virginia have a
specific definition for C/D waste that includes wood. Other states, such as
North Carolina and Washington, refer to wood as an acceptable waste in design
standards for the disposal of C/D waste materials in "C/D landfills" or "inert
debris" landfills.
2*5.3 Is Mast© Wood for Fuel Considered Recycling?
Many states have specific recycling goals due to comprehensive waste
management in response to decreasing landfill capacity; public interest in
recycling; delayed or canceled new MSW combustion facilities; increased siting
and permitting costs; and escalation of tipping fees. Several states in the
study area including California, Connecticut, New York, North Carolina, and
Vermont have adopted recycling goals of 2 5 to 50 percent within several years.
If the processing and use of waste wood for fuel does not contribute to
recycling goals, there may be greater regulatory or political barriers. In
addition, there may be less incentive for solid waste managers and regulatory
staff to review and permit waste wood facilities. No states in the study area
currently define processing and using waste wood for fuel as recycling. In
New Brunswick, this issue has not been decided either way.
2.5.4 Definitions of Wast* Wood Combuation Facilities
One of the most important regulatory issues affecting a waste wood combustion
facility is whether it is subject to the same environmental review and
permitting process as a facility that burns MSW. Definitions, regulations,
and policies vary among states and provinces, and sometimes depend on the
specific, types of wood burned at a specific facility. In addition, the
relevant regulations are developed and implemented by different divisions of a
state or provincial environmental regulatory agency, depending on the state or
province. In some states and provinces, the air permitting division of the
environmental agency has jurisdiction over the regulatory classification of
waste wood combustion facilities. In others, the solid waste permitting
division has jurisdiction, or jurisdiction is unclear, or untested.
Table 2-10 summarizes how state and provincial solid waste agencies in the
study area define a combustion facility that burns "clean" waste wood compared
to how a facility is defined if it burns "treated" waste wood. A waste wood
combustion facility generally is defined as one of three types of facilities
including an incinerator; energy or resource recovery facility; or wood
residue boiler. The actual solid waste permitting process used for a facility
varies, depending mostly on whether regulators view the waste wood as
combusted primarily for disposal or energy recovery.
• In some states, a facility is defined as an "incinerator" if it only burns
waste to reduce volume, whereas an "energy recovery facility" is defined as
an energy producer first and a waste combustion, unit second. Some states
in the study area classify "treated" waste wood combustion as
"incineration," even if the facility is developed as a power plant.
Facilities burning "clean." wood, however, are classified as "energy (or
resource) recovery" or "wood residue" facilities because the "clean" wood
is assumed to be collected for use as a fuel only and not for waste
disposal purposes. This regulatory approach is in effect in Connecticut,
New York, Washington, and Wisconsin.
2-30
-------
• In other states, the terms "incineration* ox "energy recovery" are subsumed
under broader facility definitions such as a "treatment facility" in
Vermont; "transformation, facility* in California; "energy recovery and
incineration facility* in Virginia; or "resource recovery facility" in
North Carolina. In these states, the regulatory procedure is similar to
the approach previously described. In both Vermont and North Carolina, for
example, regulators indicate that they regard "treated" waste wood
combustion as incineration, although state policy is not explicit due to
anticipated fuel and ash properties and related disposal needs.
Overall, interviews with state and provincial solid waste regulators in the
study area indicate mixed opinions about whether facilities that burn
"treated" waste wood for energy should be regulated as incinerators,
energy/resource recovery facilities, or wood residue boilers. In many cases,
no regulatory precedent exists for "treated" wood combustion, except perhaps
from the on-site burning of mill residue produced by primary and secondary
wood products industries, (In the study area, this is true in Connecticut,
Vermont, Virginia, and New Brunswick). Seven of the nine states/provinces
make a regulatory distinction, however, between the definition of "clean"
waste wood and "treated* waste wood. In most instances, state or provincial
solid waste rules consider "clean" waste wood combustion facilities to be
energy recovery facilities, while the combustion of "treated" waste wood is
defined as
the combustion of mixed municipal solid waste and is therefore incineration.
The determination of how waste wood combustion facilities are defined by solid
waste regulators can have a direct effect on the review and permitting
process. First, in many states, solid waste policies actively discourage
siting and construction of new combustion facilities that are construed to
incinerate solid waste. Yet, the source separation of wood from the waste
stream to meet recycling goals, avoid landfilling, or prevent illegal disposal
is frequently encouraged. One state, North Carolina, has a solid waste policy
that favors "incineration for energy production" compared to "incineration for
volume reduction."
Second, positions taken by solid waste regulators may be inconsistent with air
regulators in the same state or province. For example, in Washington during
review and permitting by air regulators, a "treated" waste wood combustion
facility will be viewed as an energy recovery facility. Yet, solid waste
regulators will regard the same facility as a type of incinerator. How these
issues are addressed, coordinated, and reconciled has a large impact on the
way solid waste rules and policies affect the energy recovery of waste wood,
2.5.5 Definitions of Waste Wood Processing Facilities
Several states in the study area have specific regulations for recycling
facilities that process waste wood into fuel. Regulatory definitions of the
facilities vary among states. The definitions depend on the types of
materials in addition to wood that are processed. Definitions also depend on
whether a processing facility is part of an integrated materials recovery
program., or whether it is a private supplier of fuel for power. For example,
in California, a waste wood processing facility is permitted as a "materials
recovery facility." In Connecticut, it is permitted as a "solid waste volume
reduction facility.* In New York, it is permitted as a "solid waste
management facility," In Virginia, it is permitted as a "resource recovery
system."
2.5.6 Ash Disposal Regulations
2-31
-------
Each state in the study area has established solid waste regulations that
apply to the characterization, testing, and disposal of ash fro® wood-fired
facilities. New Brunswick regulates the design of landfills, but does not
specifically regulate wood ash disposal.
The type of characterization, testing, and disposal required for wood ash.
varies among states. The regulatory determination of which is required
depends on the type of wood fuel burned, the known or expected characteristics
of the ash, and the historical {permitted) disposal method used by an ash
generator. Table 2-10 gives a summary of the type(sS of disposal allowed for
wood ash in the study area.
Some states have established specific regulations and policies or experimental
programs concerning the reuse of wood ash for other purposes. Examples
include the reuse of wood ash as a soil amendment on agricultural lands, in
the chemical extraction of heavy metals ("forced leaching"}, as a stabilizer
in cement mixtures, in vitrification with glass, and in reducing metal
solubility through chemical stabilization.
Interviews with solid waste regulators in the study area reveal the following
overall trends regarding the disposal or reuse of ash from waste wood
combustion facili ties:
• Most solid waste regulators have received minimal, if any, data on the
characteristics of ash from waste wood combustion. The primary exception
is California and other northeast states not in the study that are familiar
with land-spreading wood ash, such as Maine. This is especially true for
"treated" waste wood. Therefore, a facility intending to combust
significant quantities of "treated" waste wood will be asked to provide
test data on ash characteristics. Issues of particular interest are ash
toxicity, corrosivity and specific metals concentration.
• In many states, ash from the combustion of ."clean* waste wood {e.g.
harvested wood, some mill residue, and perhaps pallets) is assumed to have
non-hazardous characteristics. Regulators expect to invoke authority to
require ash testing, however, for "treated" waste wood. The extent of
testing will depend on how much of the fuel will be "treated1 waste wood,
the variability of waste wood used for fuel, and the known characteristics
of the fuel. Testing may be required not only for a hazardous waste
determination. It may also be required for petitions seeking to reuse the
ash for other purposes, or to assess the risk of leaching from ash to
determine appropriate land disposal options,
• The process for determining ash characteristics in most states is the same
as waste characterization procedures outlined in Subpart C of RCRA
{described In Section 2.4.1. of this report).
• Table 2-11 lists state threshold limits for selected toxicity
characteristics. Ill most cases, the thresholds are identical to federal
RCRA standards with the exception of California, North Carolina, and New
Brunswick. The Toxicity Characteristic Leaching Procedure is the generally
acceptable test, although some states use a more stringent leaching
procedure. For example, in California, a waste extraction test must be
performed if any waste exceeds a Soluble Threshold Limit Concentration for
toxicity.
• Solid waste regulators tend to be most concerned with high pH values
(greater than 12.5) in waste wood ash as well as the presence of inorganics
and heavy metals in the ash.
2-32
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• In the study area, ash from "clean* waste wood and "treated* waste wood is
usually required to be disposed of in lined landfills, or dedicated
monofills within lined landfills. Most states have a process, however,
whereby facility operators may petition a solid waste agency for a variance
from landfill disposal requirements. Variances to landfilling or
reonofilling are granted based on "inert" qualities of the ash, or its
potential "beneficial use" as a soil amendment, fill material, or aggregate
in bonding applications. In some states not in the study area, such as
Maine, Idaho, and New Hampshire, ash from "clean" waste wood is commonly
spread on agricultural land.
Table 2-11. State threshold limits of selected inorganics for toxicity
characterization {units are rog/1)-
sate Cadmium Ctifwniyw Load Mweury Nielft Sutenium Silwr Une
CALIFORNIA ft)
STtCtmofl)
TUCfaeftgl
50
9M.0
1.0
100.0
5.0
500.0
25.0
2500 0
5.0
1000.0
0.2
28.0
350.0
3500.0
20.0
2000.0
10
100.0
5.0
500.0
250.0
5000.0
CONNECTICUT (e)
5.0
t.o
SO
na
S.0
m
nt
M
1.0
5.0
«*
NORTH CAROLINA (d)
0.5
0.1
0.6
na
0.5
0.02
n«
na
0.1
5.0
na
NEW YORK (c)
5.0
1.0
5.0
nc
5.0
0.2
m
n*
1.0
5.0
na
VERMONT
Toxicity limit
Soil Amendment LimB
[mgAo dry wflt b*«t!
M
n*
1 0
10 0
5.0
1000.0
na
1000.0
5.0
2500
6,2
too
nt
15.0
1.0
SM
m&
2500 0
VIRGINIA (c)
SO
t.0
5.0
na
5.®
na
na
1.0
S.0
nt
WASHINGTON
* Danger
-------
2.6 Energy Policies in the Study Area
This section describes energy policies in the study area that affect the
siting and construction of new waste wood combustion facilities and the
conversion of existing facilities, the emphasis is on federal and state
energy policies that affect development of wood combustion facilities rather
than environmental regulations and permitting standards. Energy policies are
relevant because they can either encourage or constrain the development of
wood-fired facilities,
2,6.1 Introduction
A variety of federal and state energy policies generally affect waste wood
combustion and wood energy development. While energy policies do not usually
distinguish between the different types of waste wood, they may be critical to
successfully complete a new wood energy project or conversion.
For wood products manufacturers that use waste wood for on-site heat and steam
needs, energy policies are relevant in several ways. State or federal tax
credits for renewable energy or energy efficiency improvements may be
available. Or, states may offer incentive grants for retrofitting furnace and
boiler equipment to burn wood, provide job training in wood conversion
technologies, or help fund wood energy demonstration projects {NCEPC, 1989;
DNYSEP, 1991). These policies usually do not distinguish between the types of
waste wood used.
They may, however, be critical to the economic viability of a new wood energy
project or industrial conversion. For wood-fired power plants, energy
policies can have an important effect in several ways. Wood-fired power
plants are developed by non-utility, independent power producers (IPP) that
sell power to a local electric utility or regional utility power grid. To
accomplish this, IPP's must negotiate with utilities to determine the amounts
of power that will be provided to the utility, and the price the utility will
pay fcr the power. These negotiations are influenced by state and federal
government energy policies that affect all types of renewable energy
development. Most energy policy issues affecting wood-
fired power plants are not unique to waste'wood combustion, but apply to the
development of other renewable energy sources as well.
State energy policies and public utility commissions (PUCs) affect and may
determine the terms of power sales contracts between IPP's and utilities, the
permitted rates of return from power sales, and the role of energy efficiency
programs {VCEP, 1990). Overall, state and local energy policies are
responsive to the relative availability of power in a given region and the
marginal cost of power from other sources. If, fcr example, power from waste
wood combustion is more expensive than investments in energy efficiency or
other renewable sources, PUCs are unlikely to sanction new power purchases
from wood-fired combustion. On the other hand, if waste wood combustion is
more economic or environmentally beneficial, the PUC could encourage its use.
A variety of incentives affect development of wood-fired power plants. Direct
incentives include solicitations from public or private utilities seeking bids
on power contracts by "qualified" renewable energy sources, or the
availability of investment tax credits fcr certain types of. power sources, for
example, the early round of Standard Offer #2 and Standard Offer #4 contracts
offered by Pacific, Gas, and Electric Company in California in the early
1980's. These offers stimulated wood-fired power plant development based on a
fuel price forecast that anticipated high costs of fossil fuels in the future
{Delaney and Zane, 1992). These offers have since been withdrawn as the price
of oil and natural gas did not increase as expected.
2-34
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Indirect incentives to wood-fired power production result from high avoided
costs of alternative power sources and from public policies that value energy
from renewable resources. In many states and provinces, the economic and
environmental benefits attributed to renewable energy production, including
wood, are just beginning to be reflected in power purchase rates offered to
independent power producers (DNYSEP, 1991}.
2.6.2 Federal Energy Policies
The passage of the Public Utilities Regulatory Policy Act (PURPA) in 1978
{Section 201) guarantees certain small power producers and cogeneration
facilities the opportunity to produce and sell power to public and private
utility companies. PURPA is administered by the Federal Energy Regulatory
Commission {FERC/ whose overall purpose is to assure that adequate supplies of
energy are available for U.S. consumers that also provide sufficient rates of
return to energy providers. FERC has promulgated rules to implement PURPA
(CFR Title 18, Part 292) that determine the status of qualifying facilities
eligible for PURPA benefits. Six criteria under PURPA that affect wood-fired
power development are summarized below. Most wood-fired power plants meet
these criteria.
1. Electric utilities are required to purchase excess power offered
for sale by qualifying facilities (QF).
2. A QF is a generating project that:
• Is owned by an individual or a corporation, and no more than
50 percent by a public utility;
• Produces electrical energy primarily by the use of a
renewable sources (including biomass) as long as 75 percent
or more of the total energy input is from renewable sources;
and
• Has a power production capacity of 80 megawatts or less.
3. Electric utilities required to purchase a QF's excess energy
include, state or federal agencies, and other entities that sell
electricity.
4. The rate at which electric utilities are required to pay a QF has
three parts:
• They shall be just and reasonable;
• Not discriminate against the QF; and
• Not exceed the utilities' "avoided cost," the marginal or
incremental cost to a utility of energy or capacity which,
without supply from a QF, would have to be generated
internally or obtained externally.
5. PURPA authorizes FERC to exempt QFs (up to 30 megawatts) from
certain provisions of the Federal Power Act and Public Utility
Holding Company Act, and financial and administrative regulations
of electric utilities.
6. PURPA requires FERC to issue regulations defining QFs and setting
standards for rates.
2-35
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PURPA stimulated development of independent power plants and cogeneration
facilities using wood fuel. Access to the power grid, the determination of
rates, and conditions for the sale of power are typically regulated, however,
by state level PUCs. PUCs focus on both the cost-effectiveness and
reliability of power, and balance the interest of power producers to achieve
reasonable rates of return over the life of a plant with the broad public
interest of obtaining reliable and cost-competitive power.
Currently, many PUCs and energy policymakers are striving to enhance the role
of "demand side" pricing in power consumption by encouraging major electric
utilities to invest in and provide energy efficiency programs (VCEP, 1990;
CEC, 1990',- VA Energy Patterns and Trends, 1990) . These efforts may forestall
the development of major new power supplies in areas where energy supply is
relatively abundant compared to demand,
2.6.3 Provincial Energy Policies in. New Brunswick
Siir.ilar to the United States, most wood-fired power generation in New
Brunswick is provided by non-utility producers. Examples include large pulp
and paper mills that sell excess power to the grid, or small district heating
systems such as the facility at the University of New Brunswick in
Fredericton. As of mid-1992, the planning and development of two independent
wood-fired facilities of 25 MW net power production is underway. The
viability of small non-utility power generators is determined by "buy-back"
rates (similar to PURPA in the U.S) based on an avoided cost calculation for
alternative fuel sources. The willingness to invest in non-utility power
production is a function of the buy-back rate offered by the major provincial
utility (New Brunswick Power) and the imported costs of oil and coal. The
province has a policy to encourage non-utility generation from wood and to
encourage the provincial Public Utilities Board to promote non-utility
generation during their review of buy-back rates {An Energy Policy for New
Brunswick, 1990).
2.6.4 State Energy Policies
Most state energy planners and policymakers support, in concept, the increased
use of waste wood for fuel. In general, they believe wood fuel and waste wood
in particular can be an important part of an overall renewable energy supply
strategy. State energy planners anticipate greater wood energy recovery
opportunities in cogeneration and industrial conversion projects than in the
construction of new power plants {NWPPC, 1991; NCEPC, 1909! , In several
states, this view can be attributed to either an excess supply of power and/or
low avoided costs for qualifying facilities, both of which decrease the value
of new investments in power production. In addition, in states and provinces
with significant numbers of aging industrial boilers, conversions to new wood
burning technologies may provide the best opportunities for gains in both
energy efficiency and energy recovery from renewable sources. Table 2-12
compares energy policies and wood energy consumption in the study area.
Emerging state energy policies may enhance the role of waste wood combustion
facilities in the future. State level policies increasingly emphasize
efficiency and investment in renewable sources such as biamass, wind, and
solar power sources. As a result, PUCs are beginning to include environmental
and economic "externality" benefits and costs in ratemaking decisions for new
sources of power. These efforts are underway in states such as California,
Connecticut, New York, Vermont and in the province of New Brunswick. The
evaluation of externalities may have a positive impact on the competitiveness
of wood-fired power plants compared to conventional fossil fuel plants in time
(Richard, 1992).
2-36
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Despite the difficulty in allocating externality costs and benefits in
ratemaking decisions, energy policies and planning documents already in place ,
emphasize several economic and environmental benefits unique to biomass
combustion. State energy policymakers generally believe such benefits should
be reflected in ratemaking decisions or state economic incentive programs.
The policy perspective of energy planners may not be the same, however, as
solid waste planners and environmental regulators in the same state or
province.
Policy statements that reflect the positions of state and provincial energy
agencies are presented in the following section {2.6.5). The statements were
obtained from the most recent energy planning documents in each state or
province. Energy planners do not usually differentiate between "clean" and
"treated" wood fuel sources for two reasons. First, the use of waste wood
processed for fuel is fairly recent. In many states, energy planners are
unfamiliar with either the fuel potential or combustion characteristics of
processed wood fuel. Second, energy planners do not usually distinguish among
different types of wood fuel because the overall contribution of all wood fuel
combustion is usually small compared to oil, gas, nuclear, or coal sources.
Greater attention to wood combustion, however, is occurring due to the
presence of the wood energy industry in states such as California and
"Wisconsin, and in the province of New Brunswick. In addition, specific
policies to secure more energy from wood combustion are being developed due to
the advantage of wood compared to other energy sources, as in the province of
New Brunswick.
2,6.5 Examples of State/Provincial Energy Policies Regarding Wood Combustion
• "The use of biomass as a fuel resource can often alleviate
environmental problems associated with disposal or in-field
burning" fCalifornia Energy Development Report, 1988),
• "The severity of the environmental effects of woodburning
plants falls between gas and oil-fired generation, but wood is
not as risky as these other fuels because it can help delay
global warming* (Northwest Power Planning Council, 1991).
• "There are many advantages to expanding the use of wood biomass
fuels in Vermont... to the extent that wood replaces
non-renewable fossil fuels, there can be a significant
reduction in Vermont's production of greenhouse gases."
(Vermont Comprehensive Energy Plan, 1991).
• "...facilities awaiting approval from Connecticut DEP are
expected to use [BACTJ technologies for pollution abatement.
This in combination with complete combustion which results from
high temperatures, assure that this fuel is used in the least
polluting manner. There is concern about emissions from
demolition wood. Research is needed in this area. These
plants provide an opportunity to reduce the landfill
requirement which would otherwise be needed, and offer a much
needed market for wood residues presently left in our forests"
(Connecticut's Energy Future, 1991).
• "Biomass fuels, with the exception of municipal solid waste,
are relatively clean burning. Their low sulfur and nitrogen
content permit burning without the need for acid gas scrubbers.
Their carbon dioxide emissions on an energy basis are
comparable to coal but there is one important difference; the
2-37
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fable 2-12. Summary of wood energy use and energy policy in the study
area.
State energy policies
CA
CT
NC
NY
VT
VA
WA
WI
1 N.B.
1.
Current percentage of
total electrical
generation from all
types of wood,*
1.9%
<1%
<1%
<1%
2,3%
1.4%
<1%
0.6%
5%
2.
Percentage of total
state industrial energy
consumption from all
types of wood.b
<1%
na
na
14%
<1%
12%
32%
7.2%
40%
3.
State policy
specifically supports
•clean" waste wood
combustion.
If
X
X
X
Y
X
X
X
X
4.
State policy explicitly
recognizes wood from
the waste stream as a
viable fuel source.
X
X
mlkr
•A
X
5.
State policy wants the
combustion of wood to
increase.
X
X
X.
X
X
X
X
•JTii'
X
6,
State-level financial
incentives exist for
using wood as a
fuel.-"
X
X
X
X
Notes:
a. These figures do not include other types of biomass utilization such,as
residential firewood use, or process steam or heat for internal
manufacturing uses,
b. States typically divide wood energy consumption between residential and
industrial sectors. Seme states, such as California, evaluate biomass
energy potential among several categories including urban wood waste, mill
residue, wood from forestry, and wood from agricultural operations.
c. Financial incentives vary among states, but may include tax credits. CT
offers several tax credits for renewable energy projects, including
exemption from sales and use, and property taxes. In addition, alternative
energy systems with gross yearly sales revenues of less than $100 million
are exempt from state corporate business tax,
d. In NC, a 15% credit is available only for conversion of existing oil- or
gas-fired industrial boilers to wood fuel.
e. NY has conducted several risk sharing projects to encourage electrical
generation from waste wood combustion and other uses of biomass. Commercial
wood energy projects are also recommended for funding under the state Energy
Investment Loan Program,
f. MI is actively promoting the use of waste wood for fuel, particularly waste
generated from wood products manufacturing, through a grant program entitled
"Wood Waste Energy Incentive Program." This program awards grants to new
and existing facilities based on a formula that evaluates energy output,
cost, capacity factor, and moisture content of the fuel used.
2-38
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biological growth of biomass fuels uses carbon dioxide...thus their net
contribution to global warming is zero" (Washington State Energy office,
1989! .
• "The use of waste wood to generate heat and/or electricity holds the most
potential, especially in the near term, for the State's businesses and
industries. Generally considered to be a liability due to collection,
transportation and disposal costs, waste wood can be used to produce
energy on-site while reducing the amount of refuse deposited in
landfills" (New York State Energy Plan, Draft 1991 Update},
• "The state investment in renewable [wood] energy was approximately $1.00
per million Btu; about 25 percent of the average commercial cost of
fossil fuels in Wisconsin. Energy expenditures that remain in-state as a
result of these wood energy projects are over $1 million per year"
(Wisconsin Energy Bureau; summary of Wood Waste Energy Incentive Program,
1990).
• "In New Brunswick, biomass in the form of wood is our most significant
alternative to fossil fuel...The potential remains for a substantial
expansion in the use of wood for energy and is particularly attractive
when used for industrial process heat and in cogeneration applications"
(An Energy Policy for New Brunswick, 1990).
• Goal II of the Virginia Energy Plan indicates that state policy should
"Advance Renewable and Alternative Energy Sources in Virginia." Undey
this general goal, Objective B directs state agencies to "...research the
feasibility of burning waste wood to generate electricity.,," and, "...to
promote expanded use of wood as a supplemental or direct heat source by
using environmentally sound wood burnina technologies" (VA Energy Plan,
1991).
2.7 Bibliography - Chapter 2
2.7.1 Air
Clean Air Act Amendments of 1990. Conference Report to accompany 5.1630.
101st Congress, 2nd Session, Report 101-952. October 26, 1990.
Commonwealth of Virginia, State Mr Pollution Control Board, Department of Air
Pollution Control. Regulations for the Controland Abatement of Air
Pollution. Richmond, VA. January 1, 1985 revised up to May 1, 1990.
Commonwealth of Virginia, State Air Pollution Control Board, Department of Air
Pollution Control. Regulation Review Briefing Document, for Proposed
Regulation Revision.R Concerning Emission Standards for Non-Criteria
Pollutants. Richmond, VA.
Connecticut Department of Environmental Protection. Section 22a-174 of
Chapter 44C of the.Connecticut General Statutes. Hartford, CT.
Connecticut Department of Environmental Protection. Connecticut Public Act
90-264, Hartford, CT.
Elliot, Doug. Vermont Department of Environmental Conservation. Personal
Conversation. July 31, 1991.
2-39
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Environment Brunswick. Draft Guidelines for Compliance; Clean Environment
Act, Regulation 83-208,
Environmental Management Commission, Worth..Carolina Administrative Code,
Raleigh, NC.
Getz, Ray. Department of Air Pollution Control- Region 2. Personal
conversation. Roanoke, VA.
Haigman, Russel. DEM Planning Section, North Carolina Department of
Environmental Health and Natural Resources. Personal Conversation. July 27,
1991.
Hubbard, Allen. Wisconsin Department of Natural Resources. Personal
Conversation. July 30, 1991.
Key, Margaret. Commonwealth of Virginia, Region 2. Response letter. May 17,
1991.
National emission Standards £or Hazardous Air Pollutants (4Q CFB Part $1).
New York State Department of Environmental Conservation, Division of Air
Resources. Draft New York State Air Guide-1,... Guidelines for the Control ...of
Toxic AmbientAir Contaminants. Albany, NY. 1991.
Province of New Brunswick Natural Resources and Energy. An Energy Policy
1991-2005. New Brunswick, Canada. December, 1990.
Puget Sound Air Pollution Control Agency. Guidelines for Evaluating Sources
.of .Toxic...Air Contaminants. Seattle, WA. August 9, 1390.
loss, Tim. New York State Department of Environmental Conservation. Internal
memorandum "Application of Part 212 vs. Part 219 in terms, of burning discreet
waste streams™. Albany, NY. January 1, 1990.
Ross, Tim. New York State Department of Environmental Conservation. Internal
memorandum "Burning Creosote Treated Wood and Other Wood Wastes*. November 6,
1990. Albany, NY.
Rudell, Vicki. Wisconsin Department of Natural Resources, Air Toxics Unit.
"Wisconsin's Authority Upheld in Challenge to Air Toxics Rule". Madison, WI.
Simpson, Stuart J. Washington State Er.ergy Office. Guide to Washington's
Permits tor Biomass Energy Projects. June, 1938. Olympia, WA.
Spencer Don. New York State Department of Environmental Conservation.
Personal conversation. July 29, 1991.
Standards ofPerformance for Hew Stationary Sources (40 CFR Part 60).
State of California Air Resources Board, Department of Health Services.
Health Risk. Assessment Guidelines for Non Hazardous Waste Incinerators.
Sacramento, CA. August, 1990. Revised February, 1991.
State of California Air Resources Board, Emission Inventory Branch, Technical
Support Division. Technical Guidance Document to the Criteria and Guidelines
Regulation for AB-2S88. August, 1989.
state of New York. Environmental Conservation Law. Article 19 New York Air
Pollution Control. Regulations. Albany, NY.
2-40'
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State of Vermont Department of Environmental Conservation, Air Pollution
Control Division, Mr Pollution Control Regulations. Waterbury, VT. March,
1989,
Washington Department of Ecology. Chanter 173-403WAC: Implementation of
Regulations for Air Contaminant Sources. January 3, 1989.
Washington Department of Ecology. Chapter 173-434WAC: Solid Waste
Incinerator Facilities. Redmond, Washington. January 3, 1989.
Washington Department of Ecology. Northwest Regional Office. Chapter 111-
460WAC: Controls for Hew Sources of Toxic Air Pollutants.
Willinberg, Jay. Washington Department of Ecology. Air Quality Control
Engineer. Personal conversation. July 26, 1991.
Wisconsin Department of Natural Resources, Bureau of Mr Management. "The
Definition of Good Combustion Technology for Mood". Madison, WI. April 17,
1990.
Wisconsin Department of Natural Resources, Bureau of Air Management.
"Techniques for Good Wood Combustion". Madison, WI. August 10, 1989.
Wisconsin Department of Natural Resources. Hazardous Air Pollutants Emissions
Standards. Madison, WI. March 1, 1990.
2,7.2 Solid Waste Regulations
California Code of Regulations. Environmental Health. Title 22. Division
4, ...Section 66680. et sea. Sacramento, CA.
California Integrated Waste Management Board. California Integrated
Management Statutes. Sacramento, CA. June 1951.
California Integrated Waste Management Board. Planning Guidelines and
Procedures for Preparing and Revising Countvwide Integrated Waste
Management Plans. Sacramento, CA. July 11, 1991.
Campbell, Alton, Huang Honghan, Richard Folk, and Bob Mahler. Wood Ash as
Field study.
University of ID, Moscow, ID. December, 1990.
Campbell, Alton. Utilization of Wood Ash Workshop. University of Idaho.
Moscow, id. September 10, 1990.
Canadian Council of Resource and Environment Ministers. Operating and
Emission .Guidelines for Municipal Solid Waste Incinerators. Ottawa,
Canada. October, 1988.
Commonwealth of Virginia. Solid Waste Management Regulations. VR
672-20-10. Department off Waste Management. Richmond, VA. December, 1988.
Commonwealth of Virginia. Regulations for the Development of Solid Waste
Management Plans. Department of Waste Management. Richmond, Virginia.
May 15, 1990.
Connecticut Department of Environmental Protection, Waste Management
Bureau. Hazardous Waste Management Regulations. Hartford, CT. Revised
July 17, 1991.
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Connecticut Department of Environmental Protection. Solid Waste
Management, Title 22A. Chapter 446d, Hartford, CT. Revised 1990.
Connecticut Department of Environmental Protection. State of Connecticut
Adopted Solid Waste Management Plan. Hartford, CT. February, 1991.
Connecticut Department of Environmental Protection. Standards for Solid
Waste Landfills. Hartford, CT. Revised January, 1977,
Connecticut General Assembly. Public Act No.90-264. An ..Act Concerning
Woodburnina Facilities. Hartford, CT. 1990.
Department of Natural Resources. Wisconsin Administrative Code.
Environmental Protection. Solid and Hazardous Waste Management. Madison,
Wl. January, 1988.
Department of the Environment. Design Guidelines for Sanitary Landfill
Sites. Fredericton, New Brunswick. February, 1988.
Fields, Howard. "Congress Opens 1991 RCRA Hearings By Asking States What
They Want." Recycling Today, Cleveland, OH. June, 1991.
General Assembly of North Carolina. Senate Bill 111. An Act to Improve
the Management of Solid Waste. Raleigh, NC. 1989 Session.
General Assembly of North Carolina. House Bill 1109. An Act to Improve
the Management of Nonhazardous SolidWaste,, to Redefine the State Solid
MasteManagement Goals, and to Make. Clarifying, Conforming, and Technical
Amendments to the Solid Waste .Management Laws. Raleigh, NC. 1991 Session.
Hauser, Robert Jr., P.E., and Camp Dresser & McKee Inc. "Managing Ash",
Independent Energy. Milaca, MM. October 1991.
Ministry of Transportation. Transportation of_Dangerous Goods Regulation.
Ottawa, Canada. June 1989.
New York State Department of Environmental Conservation. The Division of
Solid Waste Technical and Administrative Guidance Memorandum. "Regulatory
Requirements for Wood Chips, Wood Chipping Operations and Wood-Fired Energy
Recovery Facilities". Albany, NY. July 25, 1991.
New York Department, of Environmental Conservation. 6 NYCRR Part 360 Solid
Waste Management .Eacilltias. Division of Solid Waste. Albany, NY.
December 31, 1991.
Rogoff, Marc J. "The Ash Debate: States Provide Solutions*. Solid Waste
and Power. Kansas City, MO. October 1991,
State of North Carolina Department of Environmental, Health and Natural
Resources, Solid Waste Management Division; Solid Waste Section. Procedure
and Criteria of Waste Determination.
Ral eigh, NC. November 7, 1990.
State of North Carolina Department of Environment, Health and Natural
Resources, Solid Waste Management Division, Solid Waste Section.
Waste Management Rules. Raleigh, NC. As Amended Through March 1, 1991.
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Stat© of Vermont Agency of Natural Resources. Hazardous Waste Management
Regulations, Department of Environmental Conservation. Waterbury, VT.
October 1, 1931,
State of Vermont Agency of Natural Resources. Solid Waste Management
Rules, Department of Environmental Conservation. Solid Waste Management
Division. Waterbury, VT. June 24, 1991,
State of Vermont Agency of Natural Resources. Solid Waste Management
Program, . Solid Waste Management Division. Waterbury, VT. 1989.
U.S. Environmental Protection Agency, Land Disposal Restrictions;
Potential Treatment Standards for .Newly.-Identified and Listed Wastes and
Contaminated Debris.... Federal Register, Vol. 56, No, 104, Washington, DC,
May 30, 1991.
U.S. Environmental Protection Agency, RCRA Title 40 - Protection of
Environment. Washington, DC. July 1, 1990,
Washington State Department of Ecology, Dangerous.Waste Regulations.
Chapter 173-30.3 WAC. Olympia, WA.. Amended April, 1991.
Washington State Department of Ecology. Minimum Functional Standards for
Solid Waste Handling, Chapter .173.-304 WAC, Olympia, WA. October 4, 1988,
Washington Department of Ecology. Wood Waste Landfills, Olympia, WA.
July 1990,
Washington State Department of Ecology. Solid Waste Management-Reduction
and Recycling, Chapter.70.95 RCW, Olympia, WA. 1989,
2.7.3 Energy Policies
Commonwealth of Virginia. The Virginia Energy Plan. Office of the
Governor. Richmond, VA. August 20, 1991.
Delaney, William P., and. Glenn A. Zane. Market Dynamics of Biomass Fuel in
California, National Bioenergy Conference. Coeur D'Alene, ID, March 19,
1991.
Deshaye, Joyce A., and James Kerstetter, Ph.D. Washington State Biomass
Data Book. Washington State Energy Office. Olympia, WA, July 1991,
Deshaye, Joyce A,, and James D. Kerstetter, Ph.D. 1990 Washington State
Directory of Biomass Energy Facilities, Washington State Energy Office,
Olympia, WA. 1990.
California Energy Commission. Electricity Report. Sacramento, CA. October
1990.
California Energy Commission. Energy Development Report. Sacramento, CA.
August 1988,
Connecticut Office of Policy and Management, Energy Division,
Connecticut's Energy Future, Making the Right Choices. Hartford, CT.
January 1, 1991.
Kerstetter, James D. Ph.D. Assessment of Biomass Resources for Electric
Generation in the Pacific Northwest. Northwest Power Planning Council,
Washington State .Energy Office. Olympia, WA. 1990.
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Moran, Daniel F. Renewable Energy Analyst. Division of Energy and
Intergovernmental Relations. Wisconsin Energy Bureau. Madison, WI.
Personal Communication. February 26, 1991 and May 8, 1991.
New Brunswick Department of Natural Resources and Energy. An Energy Policy
1991-2005. New Brunswick, Canada. December 1990.
New York State Energy Office. Renewable Resources Supply Assessment.
Draft New York State Energy Plan. 1991 Biennial Update. Albany, New York.
July 1991.
New York State Energy Office. Issue 10: Renewable Resources. Draft New
York State Energy Plan. 1991 Biennial Update. Albany, New York. July
1991.
North Carolina Energy Policy Council. 1989 Energy Report. Division of
Energy. North Carolina Department of Economic and Community Development.
Raleigh, NC. 1989.
Northwest Power Planning Council. 1991 Northwest Conservation and Electric
Power Plan, Volume II - Part II. Portland, OR. April 1991.
Richard, Jim. Energy Division. New Brunswick Department of Natural
Resources and Energy. Fredericton, N.B. Personal Communication,
February 7, 1991 and January. 13, 1992.
Solar Energy Research Institute. The Potential of Renewable Energy: An
Interlaboratory White Paper. For the Office of Policy, Planning and
Analysis., U.S. Department of Energy. Golden, CO. March 1990.
Simpson, Stuart J. Guide to Washington's Permits for Bioraass Energy
Projects. Washington State Energy Office. Olympia, WA. June 1988.
Thomas, Susie. Department of Mines, Minerals i Energy. Commonwealth of
Virginia. Richmond, VA. Personal Communication. October 30, 1991.
Vermont Department of Public Service. Vermont Comprehensive Energy Plan.
Montpelier, VT. January 19 91.
Virginia Department of Mines, Minerals and Energy. Virginia Energy
Patterns and Trends. Division of Energy. Blacksburg, VA. 1991.
Williams, Joy J. Energy Division. State of North Carolina. Raleigh, N.C.
Personal Communication. October 30, 1991.
Wisconsin Energy Bureau. Wood Waste Energy Incentive Program Summary
Report. Department of Administration. Madison, WI. October 1990.
Wisconsin Energy Bureau. Wisconsin Energy Statistics-1989. Madison, WI.
July 1989.
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3.0
HARVESTS} IfOGD AND WASTE WOOD AmUJffiHE FOE FUEL
3,1 Introduction
This chapter describes the types and amounts of harvested wood and waste
wood potentially available for fuel in the states and province studied for
this report. The purpose of the chapter is to determine the quantity of
wood currently generated in each state and province containing non-wood
materials that could affect its use as fuel. In addition, the total amount
of harvested wood and waste wood produced in each state and province is
identified, as are the types and amounts of wood that may contain non-wood
materials.
Section 3.2 begins by organizing the many different types of harvested wood
and waste wood into eight categories. General information is provided on
the types of activities that produce wood in each category. Categories of
wood that may contain non-wood materials are identified.
In Section 3.3, estimates are provided of the types and amounts of waste
wood generated in each state and province, as well as information on the
types and amounts of wood currently reused for fuel. The section
identifies the relative magnitudes of different types of wood potentially
available for fuel.
Information on industry trends likely to affect the types and Mounts of
waste wood that contain non-wood materials in the future is presented in
Section 3.4. Manufacturing rates for specific wood products, the
geographic concentration of wood product manufacturing firms, and the
geographic distribution of typical wood products are discussed. This
information indicates the likely composition of waste wood streams in the
future,
Overall, this chapter is intended to assist solid waste and energy
planners, power plant developers, and regulatory officials in understanding
the magnitude of the entire wood fuel resource, and the portion that may
contain non-wood materials. More detailed information on the composition
of waste wood that may contain non-wood materials is provided in Chapter 4.
3.1.1 Key Issues Regarding Types and Amount* of Waste Wood
• What are the major types of waste wood that may be available for fuel?
• Of the various types of waste wood available for fuel, what is the
relative magnitude of fuel available from the waste wood stream that
may contain treated material in the study area?
• For wood fuel obtained from the waste stream, what are the wood
products types likely to be found in the waste stream? What economic,
geographic, and demographic factors influence the presence of certain
waste wood products in the waste stream?
3.1.2 Key findings
• Three major wood waste types are identified as "urban* wood waste,
mill residue, and harvested wood waste. "Urban" wood waste includes
pallets, construction and demolition (C/D! wood and municipal solid
waste wood. Mill residue includes primary and secondary wood product
industry waste. Harvested wood waste includes site conversion,
silvicultural, and agricultural wood wastes.
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• Of the three major categories of wood waste, "urban" wood waste is
most likely to contain "treated" wood products, fo a lesser extent,
treated waste wood may also be produced as secondary mill residue.
The project team did not assess potential pesticide contamination of
agricultural derived fuels»
• Within the eight-state, one-province study area it is estimated that
"urban" waste wood and secondary mill residue (which potentially
contains treated wood material) comprises approximately 19 percent of
total waste wood generation prior to reuse, recycling, and disposal.
It is important to note, however, that these estimates only represent
a "snapshot* of current generation and reuse in the study area. The
actual amounts generated will change over time due to economic,
regulatory, and other factors.
• Of the total amount of waste wood estimated to be reused for fuel
within the study area, 17 percent is derived from urban waste wood and
secondary mill residues. The majority of waste wood used for fuel in
the study area is derived from primary wood industries as mill residue
and directly from harvesting operations.
• It is difficult to predict the exact types and amounts of specific
wo«d products that may be present in a given waste stream. Key
factors that assist in evaluating the likely types and levels of
contaminants of waste wood include assessing;
The level and types of primary and secondary forest products
industry in a region;
The extent of construction and demolition activities in a
region;
Climatic factors that influence the choice of-wood products
used, such as the use of pressure-treated wood in moist
climates;
The level and types of shipping, freighting, or hauling
industries in a region that create waste wood dunnage; and,
Major trends in wood products industries that affect the types
and composition of wood products produced. Examples are recent
shifts in. plywood manufacturing from the northwest to the
southeast, or the increasing reliance of the wood preservation
industry on waterborne preservatives such as CCA.
3.2 Typ®s of Waste Mood
Waste wood generally refers to wood residue generated by a variety of
forest harvesting, industrial, commercial, and residential activities. As
shown in Table 3-1, eight major types of waste wood are potentially
available for use as fuel in power plants and other industrial and
commercial combustion systems. Each type can be grouped into one of three
broad categories. "Urban" wood waste includes used pallets, wood from
construction and demolition waste, and other wood found in the municipal
solid waste stream. "Mill residue" includes waste wood generated by
primary and secondary wood industries. 11 Harvested wood" includes site
conversion waste wood, siivicultural waste wood, and agricultural residue
(CTD, 1991). Types and categories of waste wood potentially available for
fuel are described in Table 3-1.
3-2
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3.2,1 "Urban Wood Waste"
In this report, the term "urban wood waste" refers to used pallets,
construction and demolition wood, and wood that is commonly commingled with
other municipal or commercial solid waste. Common features of wood in this
group are the relatively low moisture content, usually from 7 to 20 percent
and the likelihood that some of the wood contains non-wood materials or
additives such as paints, preservatives, or glues.
Table 3-1. Categories of waste wood9.
Urban waste wood.
Pallet waste - generated from disposal of used pallets that have served
their useful life. Waste from pallet manufacturing and repair is
accounted for in secondary mill residue.
Construction and demolition (C/D) wood waste - produced from the
construction, renovation, and demolition of buildings, roads, and other
structures.
Municipal solid waste (MSW) wood - produced by a variety of residential
and commercial activities and typically commingled with municipal solid
waste.
Mill residue
Primary wood products industry waste - generated by sawmills and other
millwork companies.
Secondary wood products industry waste - produced by firms that
manufacture or use products from wood 'materials milled by primary wood
x ndustrx es.
Harvested wood
Site conversion waste wood - harvested when forest land is converted for
roads, houses, industries, business, or other development activities.
.
Silviculture waste wood - harvested during commercial harvesting, timber
stand improvement, and other forest management activities conducted to
improve the health and productivity of the forest.
Agriculture residue - including waste wood produced when agricultural
land is cleared, thinned, or pruned as well as when citrus groves and
other orchard trees die due to age, frost, or storm damage.
Notes:
a. Source - C.T. Donovan Associates Inc., 1990, 1991.
"Urban wood waste" appears in quotes because the term has not been
specifically defined by regulatory agencies or industry groups, yet it is
widely used. "Urban wood" or "urban wood waste" is used as a collective
reference for waste wood in municipal and commercial solid waste. However,
the term is actually a misnomer since the types of wood attributed to
"urban wood waste" are also found in suburban and rural locations.
Of the three urban wood waste categories evaluated in this report, the two
categories of C/D wood and MSW wood are most likely to contain significant
3-3
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4
portions of treated wood. Treated wood is defined to be non-harvested or
manufactured waste wood that is treated with paint, stain, glue, adhesives,
fire retardants, pesticides, preservatives, or other chemicals. Treated
wood may also be wood that has been contaminated in some way by exposure or
commingling with other waste, such as some types of demolition debris.
3.2.1.1 Pallet Waste
Pallet waste is generated from the disposal of" pallets that have served
their useful life. (Waste from manufacturing and repairing pallets is
accounted for in mill residue produced by secondary wood industries.) The
average weight of an individual pallet is 60 pounds. (Other wooden
shipping containers with wails weigh 100 pounds or more.) Because pallets
are bulky, they tend to present a significant disposal problem. Whenever
possible, they are repaired and reused.
Some wood fuel users prefer pallet-derived fuel compared to other sources
of "urban wood waste" because they believe pallets are a "cleaner" source
of waste wood. Used pallets have a relatively low moisture content of 15
percent and can be, but are not necessarily, free of paints, stains, or
other wood treatments.
Some pallets are treated with preservatives or water repellents, depending
on the type and grade of pallet. Pallets intended to be used outdoors or
for multiple shipping jobs may contain some chemical protection. According
to industry representatives, about 60 percent of pallets are heavy duty and
are reused as long as possible.
Pallets intended to be used indoors or for "one-way" shipping purposes tend
to be free of non-wood additives, About 40 percent are "one-way" pallets
that are used only once.
Used pallets can become available for fuel by having them delivered
directly to a combustion facility, where they are hogged or chipped in some
way. Or, waste haulers may deliver pallets to a waste wood recycling
facility that processes and sells the pallets for fuel.
Nails or staples commonly used to fasten pallets can be removed using metal
separation equipment.
3.2.1.2 Construction and Demolition Wood
Wood is a common component of construction and demolition {C/D> debris that
is produced during the construction, renovation, and demolition of
buildings, roads, and other structures. The amount of wood contained in
C/D waste varies from as low as 15 percent (based on weight) to as high as
85 percent (CTD, 1990). The actual amount depends on the source of the
waste and where in the solid waste stream the wood is measured. A recent
study by the Greater Toronto Homebuilders Association found, for example,
that 40 percent of construction waste in new residential housing consisted
of wood and wood products (GTH, 1991).
Construction and demolition wood can contain both treated and untreated
waste wood. Waste from residential or commercial construction and
renovation contains wood scraps from laminates used for sheathing and
flooring, laminated beams, moldings and casings, dimensional lumber,
painted or stained trim, and siding. Demolition debris contains painted
wood, painted sheathing, wood with plaster, wood with preservatives, wood
containing nails, and wood attached to other bulky waste such as asphalt
3-4
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shingles, tar paper, or insulation. The average moisture content of C/D
wood is about 15 percent.
Wood from construction and demolition waste can become available for fuel
in a variety of ways. Generators of C/D waste may source separate specific
components of their waste wood. Incentives for doing this are lower fees
charged by waste haulers for roll-off containers filled with the separated
wood, or lower fees charged for picking up and hauling source separated
wood.
Waste wood haulers may then deliver the source separated wood to a wood
recycling facility. The wood is processed at the facility and sold for
fuel or ether purposes. Most waste wood recycling facilities do not accept
loads of waste unless they contain at least 95 percent wood. In addition,
many recyclers only accept specific types of wood. Material delivered to a
recycler must usually meet wood specifications developed by the facility.
The processing equipment may be as simple as a mobile, outdoor tub grinder.
Or, a more complex system may be used including float tanks, metal
detectors, air classification equipment, rotary drums, hammer mills, and
dust control equipment.
Haulers may also deliver source separated wood directly to a combustion
facility, for further sorting and processing as fuel. As with stand-alone
recycling facilities, most combustion facilities that process waste wood
into fuel do not accept loads of waste unless they contain at least 95
percent wood. In addition, they usually only accept specific types of
wood. Typically, waste delivered to the combustion facility must meet wood
specifications developed by the facility. As with recycling facilities,
the types and amounts of equipment used for processing the wood varies.
Waste wood that has not been source separated and is commingled with other
C/D waste may be delivered to a C/D waste recycling facility. C/D waste
recycling facilities often have the capability to separate and process
other portions of the waste, in addition to wood.
Examples include concrete, asphalt, rubble, brick, masonry stone, topsoil,
metal, and plumbing fixtures. The processing equipment used varies,
depending on which portions of C/D waste are accepted and sold to end-use
markets. Wood fuel markets are usually only one of a variety of end use
markets served.
Commingled C/D waste may also be hauled to a solid waste disposal facility,
such as a landfill or refuse-to-energy facility. Once unloaded, wood can
be sorted from other waste before actually being landfilled or burned.
Specifications of available end use markets can be used as the basis for
determining which portions of the waste to recover. Operators of disposal
facilities may sort and process wood on site, in conjunction with other
waste separation or recycling activities. The woodfuel may be sold through
a contract with a combustion facility that specifies the types, amounts,
and price of the wood. Or, the wood may be stockpiled on site and sold on
the spot market.
3.2.1,3 Municipal Solid Waste (MSW) Wood
MSW wood includes all types of wood not specifically accounted for in
pallet waste, C/D waste wood, primary wood industry mill residue, secondary
wood industry mill residue, site conversion waste wood, siIvicultural waste
wood, and agricultural residue. This includes wood commonly found in
municipal solid waste, such as wood produced by household and small
3-5
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commercial generators that is usually handled by MSW haulers and disposal
facilities.
Examples include household yard waste, household remodeling scrap, and
wooden shipping containers (other than pallets) disposed of by retail and
grocery stores,
MSW wood tends to be produced in relatively small amounts by many different
sources, so the ability to cost-effectively separate and recover the
material for fuel is usually lower than for other types of waste wood.
This is changing, however, as the resource value of waste wood becomes
better understood, and as solid waste policies encourage more separation
and recycling of wood (CTD, March, 1991), The city of Toronto, Ontario,
for example, recently proposed a ban on landfilling loads of waste
containing more than 10 percent "recyclable" wood products (Kalin, 1991}.
The moisture contents of MSW wood varies depending on the specific type and
source of wood. An. average moisture content of 15 to 20 percent is
commonly used in the solid waste and energy Industries. However, if a
substantial amount of yard waste is present, the moisture content will be
higher.
The sorting of wood from other MSW may occur through "curbside" collection
programs, or by sorting it at landfills, transfer stations or
refuse-to-energy facilities. Since MSW wood is commingled with a wide
variety of materials, such as plastics, putrescibles, or household
hazardous waste, both an economic incentive and public commitment to waste
separation is necessary to ensure that wood is successfully removed from
other solid waste,
3.2.2 Mill Residue
Mill residue is a term commonly used in the lumber and wood products
industry to refer to waste wood produced by sawmills and other wood
manufacturing firms. Firms are commonly grouped and described as either a
primary or secondary wood products industry. Mill residue is produced by
both types of industries,
3.2.2.1 Primary Wood Products Industrie*
Primary wood products industries use whole logs to create primary wood
products, such as dimensional lumber, beams, and pulp. Examples of primary
wood products industries include sawmills, pulp and paper mills, plywood
mills and other millwork companies.
Primary wood industries produce a variety of waste wood including bark,
chips, edgings, sawdust, and slabs. Typically# the waste wood contains
minimal, if any, preservatives, paints, stains, or other non-wood material.
Sawmill and other millwork residue typically have a moisture content of 40
to 50 percent.
A high percentage of waste wood generated by primary wood industries is
recoverable for fuel and is currently reused for fuel. In fact, many
primary wood industries throughout the U.S. and Canada burn all, or a
portion of their waste wood on site for space heating, low temperature
steam, hot water, and/or power generation. Availability for new fuel
users depends on the extent of current fuel use and prices paid by other
end-use markets.
3.2.2.2 Secondary Wood Products Industries
3-6
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Secondary wood products industries manufacture engineered wood products
from pre-manufactured wood materials, sawed dimensional lumber, or primary
mill residue. Secondary wood industries include companies that manufacture
building products, such as particleboard, oriental strandboard, or
fiberboard, and also include companies that use engineered building
products and dimensional lumber to manufacture windows, doors, boats,
cabinets, furniture, pallets, and flooring. (Since plywood is typically
processed directly from logs, it is considered a primary wood product by
the forest products industry.)
Secondary wood products industries produce a variety of waste wood
including chips, ends, and sawdust. The waste may be treated with
preservatives, paints, or stains, and also contain non-wood material such
as glue, plastic, ox fabric. The moisture content of secondary wood
industry waste varies considerably because both green, harvested wood and
kiln-dried wood are used in secondary manufacturing. An average moisture
content of 45 percent is commonly used in the wood energy industry (CTD,
1990}.
A significant percentage of waste wood generated, by secondary wood products
industries is recoverable for fuel. Similar to primary wood industries,
many secondary wood industries throughout the U.S. and Canada burn all, or
a portion of their waste wood for fuel on site. The wood is used for space
heating, low temperature steam, hot water, and/or power generation.
Availability for new fuel users depends on the extent of current use and
prices paid by other end-use markets.
3,2,3 Harvested Wood
Harvested wood, a term commonly used in the forestry and energy industries,
refers to wood harvested directly from the forest that is used without
being treated or processed with any chemical additives.
In this report, harvested wood also refers to wood obtained from
agricultural land. Depending on the source, wood from agricultural sources
may contain pesticide residues.
3.2.3.1 Site Conversion Waste Wood
Site conversion waste wood consists of wood harvested when forestland is
converted for roads, houses, industries, businesses, or other development
activities. Site conversion waste wood has an average moisture content of
45 percent.
The availability of site development waste wood for fuel is a function of
the level of development. It also depends on whether it is customary in a
given geographic area to remove waste wood from a cleared site, and whether
•wood can be burned or buried on-site. When possible, landclearers prefer
to leave wood at the harvesting site, unless the material has value as
timber, pulp, landscaping mulch, fuel, or other uses.
However, site clearing contracts in urban and developed locations may
require removal of wood from the site, whether or not the wood currently
has a market value. This can result in waste wood hauling and disposal
costs that decrease the profitability of site conversion. In such cases,
landclearers are likely to seek alternatives to disposal, including reuse
for fuel.
Site conversion waste wood is currently used as fuel by a variety of
wood-fired facilities throughout the U.S. and Canada. Availability to new
3-7
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fuel users depends on whether landclearers need to remove waste wood from
the site, hauling costs, prices fuel users are willing to pay, and prices
paid by other end-use markets,
3.2.3.2 Silvicultural Wast® Wood
SiIvicultural waste wood is produced during commercial harvesting, timber
stand improvement, and other forest management practices conducted on
forestland. Similar to site conversion wood, silvicultural waste wood has
an average moisture content of 45 percent.
The availability of waste wood from silviculture is a function of many
factors, such as the extent of commercial harvesting, forest management
policy, landowner attitudes, incidence of blight or infestation that
require harvesting, and forest management techniques used in a given
geographic area. At most sites, silvicultural waste wood is left on site
as slash, unless there are timber, pulp, or fuel markets within a
cost-effective hauling distance.
Silvicultural waste wood is currently used as fuel by a variety of
wood-fired facilities throughout the U.S. and Canada. Availability to new
fuel users depends on hauling costs and prices fuel users are willing to
pay.
3.2.3.3 Agricultural Residue
Agricultural residue consists of waste wood produced during the harvesting,
thinning, and pruning of agricultural land, and also includes waste wood
produced when citrus groves and other orchard trees die due to age, frost,
or storm damage. Among the states and provirice studied for this report,
substantial amounts of agricultural residue are generated and used for fuel
in the western states due to the amount of fruit, wine, vegetable, and nut
production. Examples of agricultural residue include prunings from orange,
apple, walnut, olive, and almond trees and from vineyards. Similar to
other harvested wood, agricultural residue has a moisture content of 40 to
50 percent.
Some agricultural waste wood may contain pesticide residue. The presence
of pesticide residue in fuel derived from waste wood depends on the source
of wood, types and rates of infestation common in the wood, potential
volatilization of the pesticide residue during wood fuel storage, and the
extent to which the residue leaches from the wood during exposure to rain
before harvesting, processing, and/or combustion.
In many states and provinces, until recently most agricultural operations
burned waste wood in open piles outdoors. In some states such as
California, air quality regulations have since restricted open burning and
have created incentives by offering "emission credits" to wood-fired
facilities that burn agricultural waste in controlled combustion units.
The availability of agricultural residue for fuel depends on the location
of agricultural lands, hauling costs to fuel users, the price of wood fuel,
and the availability of emission reduction credits,
3.3 Wood Fuel Available in the Study Area
Table 3-2 is a summary of waste wood generated and reused in the study
area. This table includes information on the types and amounts of "urban
wood waste," mill residue, and harvested wood generated in the state, and
also includes information on the types and amounts of waste wood currently
3-8
-------
reused for fuel. Appendix C contains a listing by waste wood types for
each State and Province in the study area.
Three general conclusions can be made based on the profile of waste wood
generation and reuse presented in the tables for each state and province.
First, in almost all locations, the amount of waste wood generated in all
categories of wood substantially exceeds the amount currently reused for
fuel. The difference between generation and reuse is particularly large
for "urban, wood waste" and harvested wood. It is important to note,
Table 3-2. Summary of combined waste wood generation and reuse in the
study ar«a*,b c d.
Type of waste wood
Amount.generated
(1000s)
Reused for fuel (1000s) I
Urban waste wood
Pallets
c/d wood
MSW wood
2,872
5,323
4, 836
760
825
785
Subtotal
13,031
2,370
Mill residue
Primary wood industry
Secondary wood
industry
31,649
8,613
20,047
3,957
Subtotal
40,262
24,004
Harvested wood
Site conversion
Silviculture
Agriculture
15,287
42,491
4, 880
1,847
6,818
1,880
Subtotal
62,658
10,545
Total
115,951
36,919
Notes:
a. Estimates reported in thousands of green tons per year for 1990.
b. Figures for generation and reuse are the consultant's estimates based
on available data and interviews with state forestry, solid waste, and
energy officials. These numbers may vary over time due to economic
trends, forest practices, energy prices, and other factors,
c. Estimates of reuse only measure the amount of wood consumed for
combustion at industrial and commercial facilities. They do not
include residential consumption such as firewood.
d. fhis table does not include the amount of silvicultural wood that is
potentially available on a sustained yield basis front new growth and
natural mortality of biomass in the forest.
e. Urban wood waste, particularly the categories of C/D wood and MSW
wood, are most likely to contain significant proportions of treated
wood. In addition, secondary mill residue may contain tailings, tri®
scraps, or furniture ends that have been treated (i.e., coated).
3-9
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however, that other end use markets exist for waste wood in addition to
fuel including markets for waste wood used for landscaping mulch, pulp and
paper, animal bedding, binding agent in MSW and sludge compost, and
engineered building products, such as flakeboard, among others. Depending
on the state or province, the availability of other end-use markets for
waste wood may decrease the amount currently generated that could be
available for fuel, particularly for mill residue and harvested wood, which
are generally considered "clean" sources of waste wood.
Second, it is apparent from the cables that the proportion of urban wood
waste, mill residue, and harvested wood generated varies dramatically among
the states and province studied. For example, in California almost as much
"urban wood waste" is generated as mill residue and harvested wood. This
reflects, in part, the large population and urban density in the state, and
the relatively large role commercial activity has in the state's economy.
By contrast, in Vermont substantially less "urban wood waste" is produced
compared to mill residue and harvested wood. This reflects, in part, the
large forest resource in the state and the relatively large role of wood
products industries in the state's economy.
Third, it is apparent that in some areas "urban wood waste" represents a
significant biomass resource. In the future, solid waste, renewable
energy, and air quality policies and regulations will affect the extent to
which "urban wood waste" is available for use as fuel.
3.4 Industry Trends Affecting Wast® Wood for Fuel
An important objective of this report is to identify the types of waste
wood that contain nan-wood materials that nay affect the use of wood for
fuel. Examples include waste wood derived from wood products that contain
adhesives, chemical additives, laminates, or coatings.
Ideally, information would be provided on the specific amounts of waste
wood containing treatments, preservatives, or non-wood materials generated
in each state and province. However, such data are neither compiled in any
systematic way nor available from federal and state solid waste and energy
offices, or professional trade associations.
It is possible to identify the types of waste wood likely to contain
non-wood materials, and to anticipate the extent to which they are likely
to be present in the waste stream. Based on research conducted for this
report, of eight types cf waste wood investigated, three are typically
"clean" sources of waste wood harvested directly from the forest. These
include;
• Primary wood industry waste;
• Site conversion, waste wood; and
• Silvicultural waste wood.
Two types of waste wood mav contain non-wood materials such as some types
of pallets and some types of agricultural residue. However, the percentage
of non-wood material is low compared to other treated wood products
including:
• plywood;
• particle board;
3-10
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• laminated woods; and
• pressure-treated wood.
Three types of waste wood are likely to contain non-wood materials. The
presence of non-wood materials in the waste wood may affect use of the wood
for fuel, depending on the amount of material contained in the wood and on
existing and future environmental regulations including:
• Some types of wood found in construction and demolition waste;
• Mill residue from certain types of secondary wood product industries;
and
• Some types of wood found in municipal solid waste.
There are six common wood products that account for a large proportion of
waste wood that contains non-wood material. These include certain types of
pallets, plywood, painted wood, pentachlorophenol treated wood, pressure
treated wood, and creosote treated wood. Presented below is information on
industry trends for each of these wood products. This information is
presented to assist in determining how to estimate the likelihood that wood
fuel in each state and province will contain non-wood materials. More
detailed information on the chemical composition of the products is
provided in Chapter IV.
3,4.1 Pallet Waste
Pallet manufacturing is one of the major wood product industries in the
U.S. and Canada due to the widespread use of pallets and other wooden
shipping containers by businesses and industries. Pallet manufacturing is
the largest use of domestic hardwood lumber and the second largest use of
sawed wood. According to a 1991 study published by Southern Illinois
University (SIU), an estimated 460 million pallets were produced in the
U.S. in 1990, 70 percent of the total capacity of the pallet manufacturing
industry.
Several aspects of the pallet industry affect the types and amounts of
pallet waste available in the study area in the future as summarized below;
• The average distance within which pallet manufacturing firms sold most
{85 percent) of their pallets in 1390 was a 92 mile radius from the
manufacturing plant. The median distance, however, was 50 miles, due
to the shipping by a few large firms that sell nationwide.
• Only 12 percent of pallets manufactured in the three-state pacific
region and 3 percent of pallets manufactured in the eight-state
western mountain region were made of hardwood.
• Michigan and Pennsylvania had the largest number of pallet producing
firms in 1990, with more than 200 each. Presented in fable 3-3 is the
number of pallet manufacturing firms in each state and province in the
study area.
• The rate of pallet recycling was lowest in the five-state New England
region, at an average of 35 percent. The highest pallet recycling
rate was in the western mountain region, at 66 percent.
• Compared to 1980 and 1985 data, 1990 showed a significant increase in
average daily pallet production (from 611 to 835 to 900,
3-11
-------
respectively). There was also an increase in daily production
capacity in 1990.
The outlook for pallet manufacturing through 1994 is estimated to be an
annual growth rate of 2.S percent. However, better production and design
efficiencies are necessary to achieve this (Smith, 1991}. One method for
producing improved pallets is to extend their usable life by preserving the
wood with chemical treatments. According to representatives of the
National Wood Pallet and Container Association, an extensive testing
programs now underway to create a pallet that is usable for up to six
years compared to a one- to two-year lifespan for pallets today. The
"Enhanced Wood" testing program treats pallets using several layers of
epoxy, urethane, or polyurethane coatings. Thecoatings are applied in
layers of up to six to eight mils to increase the ability of the pallets to
repel water and resist wear.
3,4.2 Painted Wood
Due to the variations in paint types and formulation it is difficult to
identify key trends in the paint industry. The industry consists of many
different paint, stain, and varnishing products manufactured by many
different firms. Certain trends in paint formulations are evident,
however. For example, a federal ban on using lead in paint and the
increasing use of water-based paint are two major industry trends that
affect the types and amounts of paint present in waste wood.
Table 3-3. Characteristics of pallet manufacturing in the study area*.
Location
Number of firms
Percent of non-
Percent hardwood
producing
recyclable
pa 11 © t
pallets
pallets6
United States
California
143
45
12
Connecticut
35*
65
n
New York
168
53
? JL
North Carolina
90
50
82
Vermont
IS
65
68
Virginia
63
50
82
Washington
22
45
12
Wisconsin.
115
64
75
Canada
New Brunswick5
N/A
N/A
N/A
Total study area
€60
55
61
Total U.S.
3,222
54
71
Notes;
a U.S. data supplied by McCurdy & Phelps, Southern Illinois Universtiy,
June 1991.
b Based on regional percentages as determined by McCurdy & Phelps, June
1991.
c Figures for New Brunswick not available.
In addition, geography and climate indicate the types of exterior grade
paints likely to be used in a given region, Faints containing fungicides
3-12
-------
or insecticides, for example, are prevalent in hot, humid climates. Paints
containing protection against excessive ultraviolet rays that create
blistering or color fading are used in arid climates. Oil-based paints
which penetrate and help preserve the wood are used in extreme climates,
such as the northwestern and northeastern areas of the U.S. and coastal and
mountain areas of Canada (Nelson, 1991). Marine-grade paints are used in
coastal areas and regions with water-based recreation and transportation.
Two issues affect characteristics of paint used on wood. One is the type
of paint produced, either oil-based {sometimes called solvent based) or
water-based. The other is the type of resin base used. The resin contains
the primary film-forming ingredient of paint (Kelson, 1991). The trend in
the paint industry to increased use of water-based paints is due largely to
recent restrictions on emissions of volatile organics from oil-based
paints. It is also due to the ease in applying and cleaning water-based
paints. Of all paints produced, 80-85 percent of the interior paint market
is water-based, while 60-65 percent of the exterior paints consumed are
water-based. These figures refer to all paints, not only paints used on
wood (Nelson, 1991}.
According to the National Paint and Coating Association (NPCA),
''architectural coatings" comprise just over 50 percent of the total surface
coating market. Architectural coatings are paint products intended for
residential and other wood construction applications. Of all architectural
coatings, 25 percent are oil-based and 75 percent are water-based paints,
primarily latex.
The dominant resin bases which can be used in either oil- or water-based
paints include alkyd, acrylic, vinyl, and epoxy resins. Together, these
resin bases account for 67 percent of resins used in paint manufacturing,
according to 1989 data from the NPCA. Other resins consist of a variety of
oils, urethanes, and specialty combinations. According to 1989 data, alkyd
resins account for 2 3 percent of all resins used. Acrylic resins account
for 19 percent of the total, vinyl resins account for 17 percent, and epoxy
accounts for 8 percent.
3.4,3 Plywood and Other Wood Panels
Common building products, such as plywood and other wood panels, are likely
components of construction and demolition waste and some sources of
secondary wood industry mill residue. Plywood is one of a variety of wood
products referred to in the lumber and construction industries as
structural panels. The three basic grades of plywood are sanded,
sheathing, and specialty grades. Other wood panels include a relatively
newer group of products referred to as oriented strandboard {OSB!.
According to the American Plywood Association (APA), several changes have
occurred in the wood panel industry during the last five years. These
changes could affect the types and amounts of wood found in construction
and demolition waste, and their physical and chemical composition.
The predominant type of domestically used plywood is sheathing plywood that
is bonded with exterior grade phenol formaldehyde glues. Sheathing plywood
represents more than 50 percent of all structural panels produced, however,
several grades of sheathing may be used for interior applications with
interior grade urea formaldehyde adhesives. In addition, many types of
interior grade plywood and non-structural panel products such as sanded
plywood, underlayment, OSB, or waferboard are bonded with exterior grade
adhesives to improve strength, durability, and moisture resistance.
Exterior adhesives are used in approximately 96 percent of plywood and
oriented strandboard products (APA, 1991). The exact formulation, however.
3-13
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varies based on the application. Marine-grade classes of plywood may
contain a higher proportion of adhesive than residential wall sheathing.
Table 3-4 shows the proportions of various types of plywood produced and
distribution by region.
Table 3-4. Plywood production by class and region8 {thousands of square
feet, 3/8 in. thick basis)
Production by classes of plywood
Class
Exterior grade"
Interior grade
Sheathing (rough
finish)
12,208,289
258,478
Sanded (smooth finish)
2,240,980
250,360
Specialty (textured
sidings)
1,350,453
184,213
Oriented strandboard
5,640,722
-
Total
21,440,444
693,051
Production by region
Class
Western
Inland
Southern
Total
Total %
Sheathing
(rough
finish)
2,302,000
1,982,000
8,182,000
12,466,000
53.2
Sanded
{smooth
finish)
1,570,000
33,000
888,000
2,491,000
10.6
Specialty
(textured
sidings)
676,000
3,000
856,000
1,535,000
6.5
Oriented
strandboard5
5,640,000
24.1
Imported
from Canada
1,304,000
5.6
Total
23,436,000
Notes:
a Based on data from the American Plywood association, Tacosia, WA, 1991.
b Numbers fro exterior grade classes include several types of panels
designed lor interior uses. These include certain types of oriented
strandboard (OSB)and underlayment manufactured using exterior grade
glues.
c Regional U.S. production figures for OSB are unavailable. The U.S. is
the primary export market for Canadian produced OSB.
Several treads affect both the types and amounts of plywood and other wood
panels produced. The structural panel industry in the western region of
3-14
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the U.S., for example, is adjusting to recent changes in federal timber
harvesting policies on federal lands and timber supply constraints oa
private lands. The coastal region west of the Cascade Mountains in Oregon
and Washington lost more than 13 percent of their market share in 1990,
continuing a decline that began in 1987. The southern region of the
country from Virginia to Texas now produces the largest amount of
structural panels, 55 percent of the total. This region has gained the
largest market share since 1987, at a growth rate of roughly two to five
percent per year.
find uses for plywood and other structural panels are primarily for new
residential construction {38 percent) and remodeling {18 percent). Within
residential construction, single-family housing accounts for 84 percent of
all remodeling uses. Non-residential construction uses, such as for
commercial buildings or concrete forms, accounts for 15 percent.
Industrial uses, such as for pallets, furniture manufacturing, and
transporting equipment., account for 24 percent. within this amount,
pallets and crates account for 50 percent of all industrial uses. The
balance is shared between international exports and other residential uses.
It is apparent that timber supply constraints in the western U.S. and
production costs throughout the industry are encouraging continued
substitution of oriented strandboard for plywood. Since OSB was first
produced in 1980, production has increased steadily. OSB' now makes up
approximately 20 percent of all U.S. structural panel production. This is
excepted to rise to 24 percent by 1996. The APA assumes that all increases
in production capacity is the near term will be in OSB manufacturing. In
addition, the role of the Canadian oriented strandboard industry is
important to OSB consumption in both the U.S. and Canada. Currently,
Canada exports approximately 60 percent of its OSB production, with the
majority going to the U.S. Overall the plywood industry expects that
other "engineered1* wood products will continue to enter the market during
the next five to 10 years. These products include laminated veneer lumber,
structural panel webbed "1" beams, and structural composite lumber
products.
Statistics on manufacturing trends in wood preservation are prepared by the
American Wood Preservers' Institute (AWPI). Standards for wood,
preservation formulas are prepared by the Aaerican Wood-Preservers'
Association (AWPA) and are discussed in Chapter 4.
The most recent information on trends in wood preservation are from a 1989
nationwide survey and analysis of wood preserving facilities (Mickelwright,
1990S- According to the survey, there are 544 wood treating facilities in
the U.S. Of these, 113 plants are located in states included in the study
area for this report - The distribution of wood treating facilities in the
U.S. is shown in Table 3-5. Major industry trends identified from the
survey are;
• 97 percent of wood preserving plants use pressure treatment as a
preservation method. With the exception of Vermont and New Brunswick,
wood treating plants operate in each state within the study area.
Overall, there is a high concentration of wood treating facilities in
the southeastern U.S. Thirteen states in the southeastern and
southcentral part of the U.S. produce 56 percent of treated wood
products. Production in Worth Carolina and Virginia, combined,
account for 11 percent of all domestically treated wood.
• Volumes of treated wood break down into four groups. Creosote
solutions make up 16 percent, or 90 million cubic feet of treated
3-15
-------
wood. Pentachlorophenol accounts for 9 percent, or 49 million cubic
feet of treated wood, Waterborne preservatives, such as CCA, make up
73 percent, or 407 million cubic feet of treated wood. Fire-retardant
chemicals consist of 2 percent, or 11 million cubic feet of treated
wood.
Table 3-5, Production reported by 462 wood treating plants, by region, for
1989 (Micklewright, 1989).
Volume
treated with*
Northeast
North
Central
Southeast
South
Central
Rocky
Mountain
Pacific
Coast
Total
No. of plants
49
77
150
121
26
39
462*
All chemicals
56,608
69,258
154,006
135,803
13,011
43,122
471,807
Creosote
solutions13
11,419
18,540
11,415
32,453
1,699
.6,651
82,177
Pentachloro-
phenol
183
5,339
7,909
18,321
2,571
7,851
42,174
Waterborne
preservatives'"
43,641
44,793
131,731
82,375
8,470
26,917
338,528
Fire
retardants
1,365
586
2,951
2,054
270
1,702
8,927
Notes:
a Volume in thousands of cubic feet of lumber,
b Creosote, creosote-coal tar, and creosote-petroleum,
c includes CCA, ACZA, ACC, and CZC {333.7 million cubic feet treated
with CCA).
d Includes 453 pressure-treating plants and 9 nonpressure-treating
plants.
Most wood preservatives are designed for products used in exterior,
agricultural, and industrial applications. According to 1989 data from
AWPI, three major wood product groups account for 88 percent of the wood
preservatives used. Southern pine accounts for 71 percent of all treated wood
products. (An exception to this are crossties, switch ties, and bridge ties,
of which 92 percent are manufactured using hardwood species.)
More detailed information on end uses for various wood preservatives is
provided in Table 3-6. The three major wood products are:
• Lumber and timbers make up 63 percent of the total volume of wood
treated with preservatives. They are treated primarily with waterborne
preservatives (97 percent). Of the waterborne preservatives used, 98
percent consist of formulations of chromated copper arsenate (CCA).
• Crossties, switch ties, and bridge ties comprise 11 percent of the total
volume. They are treated entirely with creosote solutions.
• Utility poles comprise 14 percent of the total volume of wood treated.
3-16
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Table 3-6. Production of treated wood in the United States for 1989" {Micklewright, 19891.
Volume
treated
with1'
Cross-
ties
Switch
St
bridge
ties
Poles
Cross-
arms
Pilings
Fence
Posts
Lumber
Timbers
Ply-
wood
other
All products
All
chemicals,
1988
57,770
6,315
71,191
1,473
9,699
12,404
359,865
45,017
12,705
22,707
1988
1989
All
chemicals,
1989
58,022
6,301
73, 975
1,881
9,678
14,377
306,577
43,951
13,189
28,992
599,145
556,943
Creosote
solutions0
58,022
13,522
13,522
34
3,895
2,320
2,364
2,097
1,315
90,481
89,870
Pentachlo-
rophenol
44,959
1,768
4
709
445
1,107
394
47,896
49,386
Waterborne
preserva-
tives"
—_
15,494
79
5,779
11,348
298,443
40,747
8,636
26,415
450,565
406,941
F .1 re
retardants
—
5,325
4,553
868
10,230
10,746
Notes:
a Based on reported production of 462 treating plants {Table 3-5) plus estimated production of 91
nonreporting plants.
b Volume in thousands of cubic feet of wood,
c Creosote, creosote-coal tar, and creosote-petroleum,
d includes cca, acza, acc, and czc (98+% CCA).
-------
Approximately 60 percent of treated utility poles are preserved with
pentachlorophenol. Another 20 percent are poles treated with creosote
solutions. The remaining 20 percent are poles treated, with waterborne
preservat ives.
According to a 1989 survey, 16 wood treating facilities that use
pentachlorophenol are located in the study area for this report. Of these,
the state of Washington has the highest concentration of facilities (nine)»
followed by North Carolina and California with three each, and Wisconsin with
one. No treatment facilities using pentachlorophenol were reported in
Connecticut, New York, Vermont, or New Brunswick.
Nationwide, out of a total of 70 operating plants, wood treating facilities
that use pentachlorophenol are most heavily concentrated in Missouri {nine},
Washington (nine), Montana (six), Idaho (six), Alabama (five) and Georgia
{five} {Greenpeace, 1989).
3.5 Bibliography - Chapter 3
ADI Limited. A Study of the Economic Availability of Wood Residues for Fuel
inMew Brunswick. Energy Division, Department of Natural Resources and
Energy. Predericton, New Brunswick. December 1987.
Anderson, Robert G. Regional Production and Distribution Pattern of the
Structural Panel Industry. American Plywood Association. Tacoma, WA. April
1991.
C.T. Donovan Associates, Inc. Opportunities and Constraints Associated With
Using. Wood Waste for Fuel in Connecticut. State of Connecticut Office of
Policy and Management, Energy Division. Hartford, Cf. June 1990.
C.T. Donovan Associates, Inc. Recycling Construction and Demolition Waste in
Vermont. Vermont Agency of Natural Resources. Waterbury, VT. December 1990.
C.T. Donovan Associates, Inc. The Supply and Price of Woodfuel for a
Wood-Fired .Power Plant Planned inEast.Bvegata, Vermont. ABN Bank. Chicago,
IL. December 1990.
C.T. Donovan Associates, Inc. The Supply and Price of Woodfuel for a
Wood-Eired Power. Plant Proposed in Weathersfield. Vermont. Bonneville Pacific
Corporation. Salt Lake City, UT. July 1991.
C.T. Donovan Associates, lac. Waste Wood Resour.es Supp.1v Assessment. The New
York State Energy Research and Development Authority. Albany, NY. August
1990.
Donovan, Christine T. "Construction and Demolition Waste Processing; New
Solutions to an Old Problem". Resource Recycling. Portland, OR. August
1991.
Donovan, Christine T. "Wood Waste Recovery and Processing". Resource
Recycling. Portland, OR. March 1991.
Greater Toronto Home Builder's Association. Making a...-Mol..ahill Out of a
XLi —SJlft—XlmJSLfi .8 * North
York, Ontario. 1991.
Kalin, Zev. "Canada Targets C&D Debris". BioCycle, Emmaus, PA. January
1991.
3-18
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Kerstetter, James D, PhD, Assessment of Biomass Resources for Electric
Generation in the Pacific Northwest. Washington State Energy Office,
Olympia, WA.
McCurdy, Dwight R. and John E, Phelps.
States 1980, 1985, and 1990, Department of Forestry, Southern Illinois
University at Carbondale. Carbondale, IL. June 1991.
Micklewright, James T. Wood Preservation Statistics, 1989: A Report.,,.to the
Wood-Preserving Industry in the United States, American Wood Preservers
Institute. Stevensville, MD, December 1989.
Natural Resources and Energy Department of Hew Brunswick, .An Energy Policy
1991-2005. New Biunswick. December 1*90
Smith, Paul M. "The Washington State Wood Pallet Industry", Forest Products
Journal. Volume 41, Number 5. Madison, WI, May, 1991,
USDA Forest Service. 1989 Timber Survey, State of Virginia, 1989.
USDA Forest Service. Wisconsin Timber Industry - An Assessment of Timber
Products Output and Use. 1988, St. Paul, MM. November 7, 1990.
Van Strum, Carol and Paul Merrell. The Polities of Penta. Greenpeace U.S.A.
Seattle, WA. 1989.
Washington State Energy Office. 1990 Washington State Directory of Biomass
Energy Facilities. Olympia, WA. 1990.
Washington State Energy Office. 1990 Wood Residue Survey and Directory of
Secondary WoodProcessing Facilities in Washington State. Olympia, WA. 1990.
Wisconsin Energy Bureau. EagiJLiJlLea.
Second Edition. Madison, WI. August 1990.
3-19
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4.0
THE COMPOSITICW OP H&IWESTBD WOOD AHD WASTE WOOD
4,1 Introduction
This chapter describes the composition of harvested wood and waste wood that
could potentially be processed and used, for fuel. The purpose of the chapter
is to identify the contents of harvested wood as well as waste wood derived
from wood products that were processed or treated in some way. The chapter
focuses on the presence of non-wood material in coition wood products, and on
the composition ot the non-wood materials. The chapter is intended to assist
solid waste and energy planners, power plant developers, and regulatory
officials in understanding characteristics of waste wood that may affect its
use as fuel,
The chapter begins by organizing the many different types of waste wood that
could potentially be processed for fuel into five wood product groups. The
groups are developed, based on the type of process or treatment used for wood
in the groups. This is done to identify common wood products that are
processed and treated in similar ways. Methods of preparing and treating wood
products in each group that result in adding non-wood material are described.
The concentrations of different chemicals used during processing and treatment
are discussed.
Section 4.3 summarizes the composition of harvested wood and of common
treatments used on wood, and provides information on chemical elements
contained in adhesives, chemical additives, laminates, and coatings applied to
wood. It also provides information on various compounds used to bind and
preserve wood products.
Adhesives used in wood products are described in Section 4.4, Information is
provided on the chemical composition of various adhesives, way is] in which
adhesives are applied to wood, and the frequency and extent to which adhesives
are used in wood products. Emphasis is on formaldehyde-based adhesives,
isocyanate-based adhesives, Moresins, and other adhesives.
Preservatives used in wood products are described in Section 4.5. Information
is provided on the chemical composition of various preservatives, way{s) in
which wood is treated with preservatives, and the frequency and extent to
which preservatives are used in wood products. Emphasis is on creosote based
preservatives, oil borne preservatives such as pentachlorophenol and copper
naphthenate, and water-borne preservatives such as chromated copper arsenate
or CCA.
Materials used as surface coatings on wood are described in Section 4.6.
Information is provided on the chemical composition of various coatings,
way(s) in which coatings are applied to wood, and the frequency and extent: to
which different coatings are used on wood products. Emphasis is on metallic
pigments and major wood coatings, including paints and stains, water-based
coatings, lacquers, varnishes, enamels, and polyurethanes.
Finally, Section 4.7 identifies and describes the physical and chemical
characteristics of harvested wood as well as six wood products commonly used
throughout the U.S. and Canada. Because the wood products are commonly used,
they are potential sources of waste wood that could potentially be processed
for fuel. In addition to harvested wood, the wood products described include:
pallets, painted wood, plywood, particlaboard, pressure-treated wood, and
creosote treatod wood.
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4.1.1
Key Issues Regarding The Composition of Waste Wood
• • What are the major wood product types that may contain contaminants of
concern?
• What are the major types of adhesives, preservatives, and surface
treatments (paints and stains) used in wood products manufacturing?
• What are the physical and chemical characteristics of wood product types
most likely to be found in the waste stream?
4,1,2 Key Findings
• Major wood product groups chat contain non-wood Material include
structural and non-structural panels {containing glues and adhesives);
impregnated wood treated with oil-borne or water-borne preservatives;
and, painted wood containing oil- or water-based coatings.
• Adhesives rely primarily on phenolic resins, and to a lesser extent, urea
and resorcinol resins. Impregnated wood consists primarily of oil-borne
preservatives such as creosote and pentachlorophenol, and water-borne
preservatives such as CCA. Paints have the greatest product diversity,
however, they comprise the lowest percentage by weight {usually less than
0.1 percent) of non-wood contaminants found in waste wood.
• Non-structural panels bonded with either interior or exterior grade
adhesives tend to have higher percentages of non-wood material {5 to 15
percent.) compared to structural panels due to their reliance on the
adhesive for torsional strength.
• Three-quarters of all wood preservatives used for impregnating wood are
water-borne formulations of CCA due to the product's wide applicability
in commercial and residential uses, the absence of odor and vapors,
and durability.
• Typical paint formulations contain about 35 percent binder and 35 percent
filler which comprise the paint vehicle. The remaining 30 percent
C vTiS aS i«S of a combination of primary and secondary pigments. Paint
vehicles are increasingly water-based due to restrictions on volatile
organic emissions from oil-based formulations. Primary pigments often
consist of titanium dioxide, while secondary pigments (typically less
than 5 percent of the overall formula! may contain metals.
4.2 Wood Product Groups Containing Non-Wood Material
There are many types of wood that can potentially be processed and used as
fuel at power plants, industries, and businesses. Throughout the U.S. and
Canada, interest is growing in separating wood from the waste stream and
processing it for fuel. This is causing increasing interest in the physical
and chemical characteristics of a wide variety of waste wood types.
The varieties of processed waste wood have been organized into the following
groups:
• structural panels;
• non-structural panels;
• .impregnated wood;
• surface coated wood; and
• wood containing physically separable items.
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4.2.1
Structural Panels
Plywood, laminated beams and trusses, oriented strandboard, parquet floors,
and wood products overlaid with decorative veneers are examples of common wood
materials referred to in the lumber and construction Industries as "structural
panels." Structural panels are wood products that are designed and
manufactured to obtain strength from alternating patterns of thin wood layers,
file two basic types of structural panels Include laminated wood products and
oriented strandboard (OSB).
Laminated wood products, such as plywood, are the most common type of
structural panels. As defined by the American Wood-Preservers1 Association
(AWPA), laminated wood consists of "layers of wood fastened together {usually
glued) with their grain direction parallel to the longitudinal direction of
assembly" (AWPA, 1990!. Most laminated wood is produced by "pressing" the
wood together using high temperatures (referred to as "heat pressing"/ and by
using moisture-resistant phenolic resins as adhesive. The resin and other
additives, usually paraffin wax, make up 2 to 5 percent of the dry weight, of
the laminated wood product. Uses for structural panels include sheathing for
floors, roofs, and walls.
Oriented strandboard !OSB} products are a recently developed class of
structural panels. The predecessor to OSB is known as "waferboard" or the
common registered trade name of "Aspenite" {Lowood, 1991). The design and
manufacturing of oriented strandboard combines techniques used in laminated
wood and in non-laminated wood composites to produce a different type of
structural panel. As with laminated wood, OSB consists of multiple layers of
wood fastened together with the grain lined up parallel to the longitudinal
direction of assembly. The major difference between OSB and laminated wood,
such as plywood, is that smaller pieces of wood, instead of sheets or veneer,
are used in oriented strandboard. As with laminated wood, OSB is produced by
heat pressing the wood using moisture- resistant phenolic resins as adhesive.
To date, OSB is the only type of wood composite considered as structural
panels. Recent advances in wood composite and adhesion, technology used to
produce oriented strandboard allow some OSB products to be substituted for
laminated wood in structural applications.
4.2.2 Non-Structural Panels
Hardboard, medium-density fiberboard (MDF), particleboard, chipboard, and
registered trade names such as "Masonite" are examples of coffion wood products
referred to iri the forest product industries as "non-structural panels." This
group of wood products also includes panels containing wood laminated to
non-wood materials, such as plastic.
Unlike structural panels, the strength of non-structural panels depends
primarily on adhesive and bonding systems used when manufacturing the wood
products. The panels are shaped into rough "mats" before being heated,
pressed, and trimmed to their final shape. Non-structural panels are
manufactured using both phenol and urea formaldehyde resins. Non-wood
materials account for 5 to 15 percent of the dry weight of non-structural
panels. Typical uses for non-structural panels include interior applications
as flooring, sheathing, cabinets, and furniture.
4.2.3 Impregnated Wood
Impregnated wood products are treated with a variety of chemicals to resist
rot, decay, infestation, and moisture. Impregnated wood products are
typically pressure treated with, or soaked in aromatic organic hydrocarbon
solutions or inorganic arsenical based preservatives. Hydrocarbon solutions
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contain either creosote, coal tar, chlorinated phenols, or a combination of
creosote and oil. Inorganic solutions contain compounds of arsenic, chromium,
copper, zinc, and ammonium.
Creosote-treated wood is a common impregnated wood product. Creosote
solutions account for approximately 14 to 20 percent of the dry weight of the
treated wood. More concentrated solutions are used in wood treated for marine
applications. Creosote- treated wood is widely used in railroad crossties and
landscaping walls in concentrations of 6 to 15 pounds per cubic foot. Marine
pilings and docks are treated up to 20 pounds per cubic foot, depending on the
exposure to salt or fresh water.
Wood treated with pentachlorophenol (also referred to as "penta"} is another
common impregnated wood product. Penta is used almost exclusively in the
treatment of utility poles and pilings. Penta accounts for up to 1.5 percent
of the dry weight of the wood, depending on the species of wood used (this is
equivalent to 0.60 pounds per cubic foot). Penta applied to material used for
decking and fencing is applied with retention rates of 0.40 to 0.50 pounds per
cubic foot (AWPA., 1990) .
Inorganic preservatives include chrotnated copper arsenate (CCA) and antmoniacal
copper arsenate (ACA). CCA and ACA are used extensively in the treatment of
southern pine and other softwoods (Brennan, SPTA). There are different grades
of CCA and ACA, each containing varying fractions of arsenic, chromium,
copper, and zinc. CCA- and ACA-treated wood is used in agricultural
stockyards and fences, residential fences, decks, playgrounds, and other
exterior applications. For CCA- and ACA- treated wood used in non-marine
applications, CCA and ACA account for 1 to 3 percent of the dry weight of the
wood. This is equivalent to the CCA and ACA being applied at retention rates
of 0.25 to 0.40 pounds per cubic foot. Marine applications of CCA and ACA are
specified in ranges of 0.60 to 2.5 pounds per cubic foot (AWPA, 1990} . The
amount used depends on the species of wood, and the level of exposure to salt
water and marine borers such as Limnoria Tripunctata.
4.2.4 Surface-Coated Wood
Paints, stains, varnishes, lacquers, or fungicide sprays are examples of
materials applied to the surface of wood products for a variety of decorative
and protective purposes. Coatings can be applied to pallets, plywood,
softwood siding, wood shingles, waferboard, pine trim, hardwood floors,
furniture, decks, fences, and other wood products.
Compared to the previous three categories, painted or coated wood products
contain a small fraction of non-wood material, usually less than 0.1 percent
because most coatings are applied as a thin surface film or as a slight
impregnation of the surface of the wood. Surface coatings usually consist of
combinations of natural oils, volatile organi.es, plastic acrylic or alkvd
resins, and pigments. Pigments used in paint may contain metal compounds of
chromium., copper, lead, mercury, or zinc. However, pigments usually account
for less than 5 percent of a paint solution. Houses and buildings built
before 1940 may contain painted wood that contains lead. The paint may
contain 30 to 50 percent lead.
4.2.5 Wood Containing Physically Separable Itams
Waste wood produced by construction and demolition activities or commingled
with municipal solid waste may contain a variety of non-wood materials that
can be physically separated from the wood. Examples include pallets
containing nails; wood sheathing attached to asphalt shingles or fiberglass
insulation; wood framing with electrical wire or plumbing fixtures attached;
4-4
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or wood cabinets or furniture attached to upholstery. Most of these items can
be physically separated, from the wood by source- separating the material at
the site of generation, manually sorting the material at a wood waste
processing facility, and/or using a variety of mechanical sorting devices.
Listed in Table 4-1 are examples of non-wood items that may be present in
construction, demolition, and municipal solid waste that can be physically
Table 4-1. Physically separable items contained in waste wood®
Construction Wastes
Fiberglass insulation
Metals
Ferrous
Nonferrous
PVC plastic
Gypsum drywall
Moisture barrier films (I.e., Tyvek*)
Asphalt shingles
Tarpaper
Foam rubber
Cardboard shipping containers
Concrete
Dirt, rubble
Ceramic or porcelain tiles
Gypsum or plaster drywall
Vinyl linoleum
Metals
Ferrous
Nonferrous
Tarpaper
Electrical wire
Asbestos
Painted or stained wood
Asphalt shingles
Urea formaldehyde foam insulation
Municipal solid waste
Furniture scraps
Upholstery
Stereo and other electronic components
Home improvement waste {similar to C/D waste}
a. This is a partial list that demonstrates the range of materials that can
be physically separated from waste wood.
separated from waste wood. Information in the table represents a partial
list, and is intended to demonstrate the wide range of material that can be
physically separated from waste wood.
The potential use of woodfue'l from waste wood containing physically separable
non-wood material depends on the fuel specifications of a combustion facility
and on the way the wood is processed into fuel. Techniques vary for
physically removing non-wood material from waste wood while processing it for
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fuel. Some processing facilities only accept wood that does not contain
non-wood material. Other facilities accept wood containing non-wood
materials, and then separate the material on-site by manually sorting and
mechanically processing the waste wood.
4.3 Components of Harvested Wood and Comon Wood Treatments
This section summarizes the composition of harvested wood and common
treatments used on wood. The summary provides information on chemical
elements that are contained in adhesives, chemical additives, laminates, and
coatings applied to wood. It also provides information on various compounds
used to bind and preserve wood products.
Table 4-2 presents a list of chemical elements and their functional groups
that are contained in adhesives, chemical additives, laminates, and coatings
applied to wood. Table 4-3 presents a listing by chemical function of the
various chemical compounds used as wood adhesives, additives and coatings.
The tables, prepared by the National Forest Products Association !NFPA),
identify the primary chemicals and chemical functions that may be present in
both harvested wood and waste wood. As shown in Table 4-2, the primary
chemical components of trees include cellulose, hemicellulose, and lignin that
occur in varying amounts, depending on the species of tree. Hardwoods
generally contain more hemicelluloae and less lignin than softwoods (Tillman,
1981}. Cellul ose and hemicellulose, collectively described as holccellulose,
determine the total carbohydrate concent of wood. Lignin is considered the
•glue" in wood chemistry. Lignin helps form new proteins and accounts for the
nitrogen when wood is combusted. Wood is slightly acidic, with pH levels
typically ranging from 3 to 6 {Baker, 1987).
As show in both tables, additional chemicals are present in wood if the wood
has been processed or treated with adhesives, additives, laminates, coatings,
or other compounds. This chapter also presents additional information on the
chemical composition of contnon wood treatments. Further information on the
presence of the chemicals in wood or ash produced from combusting waste wood
is presented in Chapter 7. The air emissions from various types of waste wood
are discussed in Chapter 8,
4.4 AdhMivea Used in Wood Products
The most common adhesive system used in wood products is thermosetting resins
that contain phenol formaldehyde and urea formaldehyde resins. Less common,
more specialized, and more expensive resins consist of resorcinol and melamine
formaldehyde resins. These resins use formaldehyde as a "cross-linking agent"
to bond individual urea, phenol, and other molecules (Wardell, 1991). Less
well-used adhesive systems include isocyanate (Methylane-diphenyl-diiaocyanate
{MDI)> and bioresins.
4.4.1 Pora&ldahyd* Reaina
Phenolic formaldehyde resins are waterproof and typically used in exterior use
structural panels, such as softwood plywood and oriented strandboard where
resistance to moisture damage is needed. Typically, resins account for 2 to 4
percent of the dry weight of phenolic-bonded structural panels. Less
expensive urea formaldehyae resins are used in wood products designed for
interior applications, such as hardwood plywood, medium density fiberboard,
and particleboard. Typically, glues account for 4 to 8 percent of the dry
weight of non-structural urea-bonded panels; however, some brands of medium
density fiberboard may contain up to 10 percent resins.
Resorcinol and melamine formaldehyde resins are used primarily in laminated
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fable 4-2. Chemical elements used in wood products'.
Solid wood
N
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Due to the expense of some resins, concerns about exposure to formaldehyde
during manufacturing, and the 'offgassing" of formaldehyde vapors after
manufacturing, th e wood panel industries are using and experimenting with
other adhesive systems including i socyanate, "bioresin:;", and epoxy.
Table 4-3. Chemical compounds used in wood products®.
Cellulosic compounds
Amino compounds
Phenolic compounds
Wood
Paper
Ethyl cellulose
Urea formaldehyde
Melamine formaldehyde
Urea
Ammonia
Urethane
Casein
Melamina
Alkyd urea
Isocyanate
Phenol formaldehyde
Resorcinol formaldehyde
Aromatic Hydrocarbons
Haleg«nated hydrocarbons
Phosphorus compounds
Polystyrene
Styrene/butadiene
Polyvinyl chloride
PVA/PVC
Amino and ammonium phosphates
Boron compounds
Sulfur compounds
Arsenic compounds
"
Sodium borate
Boric acid
Aramoniun sulfate
Copper chromium arsenate
Ammonical copper arsenate
amnionicaI copper zinc arsenate
Ethers and esters
Nitro compounds
Epoxy
Waxes
Al Jcyds
Cellulose acetate butyrate
Polyvinyl acetate
Polyester
Hi trocellulose
a. From National Forest Products Association {June 1989}
Methylene-diphenyl-diisocyanate {MM) and other isocyanate derivatives are
being used as bonding agents predominantly in oriented strandboard in
conjunction with typical phenolic resins. The benefits of isocyanate
compounds are the increased strength, greater moisture tolerance, rapid
curing, and absence of formaldehyde emissions. Although most experience with
isccyanates has been in particleboard bonding, future trends indicate
increasing use of isocyanates in waferboard and oriented strandboard (Steiner,
1986) .
Bioresins are produced by extracting the natural lignin in wood and processing
it into adhesive using a steam hydrolization process that extracts
lignin-resin compounds from wood (Shen, 1989}. The extracted bioresins are
then used to "re-bond" wood fibers or flakes in pressed mats, similar to the
way non-structural composite wood products are manufactured. Current
experimentation with the production and use of bioresins raav eventually
develop a new group of more environmentally acceptable adhesive systems.
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Epoxy is an elastomaric adhesive that has advantages in structural and
non-structural applications where strength and flexibility are necessary.
Epoxy resins are reaction products of epichlorohydrin and polyhydric phenols
that are mixed with a "cross-linking" agent for hardening.. The use of epoxy
is limited to wood-plastic composite products and as an additive to phenolic
resins. {Hsu, 1388).
4,4,3 Other Adhesivas
Other adhesives that are currently used in laminated wood and wood composites
are polyvinyl acetate, casein, water based latex, and hot melts containing
polyesters, polyantides, or ethylene vinyl acetate. Asphalt distilled from
petroleum is also used in some products (NFPA, 1989), These adhesive systems
are more specialized, and are used less frequently than phenol and urea
formaldehyde resins.
4,5 The Composition of Wood Preservatives
standards for wood preservation are specified each year by the American
Wood-Preservers * Association (AWPA). Information on industry trends and
manufacturing rates are available from the American Wood Preservers' Institute
(AWPI}.
The AWPA publishes a comprehensive guide on recommended wood preservation
formulations and standards for chemicals used in wood treatments,• Overall,
the process of preserving wood is designed to treat both the surface and
subsurface layers of wood. There are three general categories of
preservatives: organic preservatives, including creosote based preservatives;
organometallic preservatives, including oil-borne preservatives; and inorganic
preservatives, including water-borne preservatives, fable 4-4 gives a list of
major categories and formulations of wood preservatives, according to the
AWPA.
Preservatives are applied either using a series of hot and cold vats or baths,
or by pressure treating the preservative to the wood in pressurized cylinders.
When using pressure-treating techniques, the wood is often incised with small
holes to maximize coverage of the preservative beneath the Table 4-4 surface.
Subsurface penetration is typically required from 1 to 2,5 inches {Clauser,
1976; AWPA, 1990). The selection of preservative and the method of treatment
depends on the intended use of a wood product and climatic considerations.
Wood products used in marine applications or other settings with high rates of
moisture, infestation, or decay generally contain higher proportions of
preservative,
According to the AWPI, three types of preservatives were used on approximately
90 percent of pressure treated wood produced in the U.S. in 1988, Creosote
solutions were used in 15 percent? pentachlorophsnol solutions were used in 8
percent, and waterborne inorganics (primarily CCA solutions) were used in 75
percent (Mickelwright, 1989; ERI, 1991). In 1990, the Environmental Research
Institute (ERI) analyzed how much of each preservative was used in pressure-
treated wood, drawing on the AWPI 1988 data. According to ERI, "upper bound"
concentrations of preservatives used in pressure-treated wood indicate that an
average volume of one gallon of creosote was used per cubic foot of creosote-
based, pressure-treated wood. An estimated ,45 pounds of pentachlorophenol
were -used per cubic foot of pentachlorophenol treated, pressure-treated wood.
An estimated .35 pounds of inorganic salts from CCA were used per cubic foot
of CCA-treated, pressure-treated wood (ERI, 1991),
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4.5.1
Creosote Preservatives
Creosote preservatives are blended solutions of creosote and various
petroleum-based oils or coal tars. Creosote is defined by the wood preserving
industry as a "distillate of coal tar produced by high temperature
carbonization of bituminous coal...," that includes, "...liquid and solid
aromatic hydrocarbons that also contain some tar acids and tar bases" (AWPA,
1990) .
fable 4-4, Major categories of wood preservatives8.
Organic preservatives
creosote
creosote for marine use
Pentachlorophenol in volatile petroleum solvent (LPG>
Pentachlorophenol in light hydrocarbon solvent
Pentachlorophenol in chlorinated hydrocarbon solvent
Pentachlorophenol in petroleum
80/20 creosote-coal tar solution
70/30 creosote-coal tar solution
60/40 creosote-coal tar solution
b0/50 creosote-coal tar solution
Creosote-coal tar solution for marine use
80/20 creosote-petroleum solution
70/30 creosote-petroleum solution
60/40 creosote-petroleum solution
50/50 creosote-petroleum solution
Organonwtallie preservatives
Copper naphthenate in creosote
Copper naphthenate in petroleum
Copper-8-quinolinolate
Tributyltin oxide
Inorganic preservatives
Acid copper chroniate (ACC)
Ammoniacal copper arsenate {ACA)
Chromated Copper arsenate (CCA Type A)
Chromated zinc chloride (CZCJ
Copperized chromated zinc arsenate fCuCZA)
Chromated copper arsenate (CCA Type S)
Chromated copper arsenate {CCA Type C)
Ammoniacal copper zinc arsenate {ACZA)
a. From the American Wood-Preservers' Association Standards, 1990,
AWPA standards specify a range of 50 to 80 percent creosote for solutions
containing creosote-petroleum oil combinations. Such solutions are well
suited for use in arid climates. Another common creosote solution mixes
creosote with coal tar. This solution contains a 20 to 50 percent creosote to
coal tar combination, and is often used to treat railroad ties, posts, and
marine pilings (AWPA, 1990)- A marine-grade creosote solution is specified by
AWPA that may be either a coal tar creosote mixture, or a coal tar creosote
chl.orpyri.fos mixture. The chlorpyrifos mixture contains at least 50 percent
chlorpyrifos for use in resisting marine organisms that attack wood (AWPA,
1990) .
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Standards for the retention of creosote in wood are usually in the range of 8
to 10 pounds per cubic foot of treated wood. This is equivalent to about 14
to 20 percent of the dry weight of the wood (ERI, 1991; AWPA, 1990), Over
time, however, creosote solutions used to treat wood leach and oxidize. Used
railroad ties that are ten years old, or older, may contain only 4 to 6 pounds
of solution per cubic foot of wood, ox about ? to 13 percent of the dry weight
of the wood (Brennan, 1991}. It is estimated that 20 to 50 percent of the
preservative may leach or oxidize from creosote-treated wood over a 10 to 25
year period (Arsenault, 1973).
4.5.2 Oil-Borne Preservatives
Oil-borne preservatives are applied to wood in an oil-based solvent which
serves as a carrier. Oil-borne preservatives consist primarily of
pentachlorophenol (penta) or copper naphthenate. Oil borne preservatives may
also include other metallic solutions, such as combinations of tin
(tributyltin oxides}, copper-nickel compounds (Copper-8-Quinolinolate), or
alkyl ammonium compounds (AAC).
Penta is a crystalline aromatic compound containing, "...not less than 95
percent chlorinated phenols" (AWPA, 1990). Penta has a distinct odor which
limits its use in many residential, commercial, and marine applications. The
preservative solution typically contains 5 to 8 percent of penta by weight.
AWPA standards require that 0.4-0.6 pounds of penta be retained in each cubic
foot of penta treated wood, depending on the intended use of the wood. This
is equivalent to the penta accounting for 1.4 percent of the dry weight of the
treated wood (ERI, 1991).
A major concern about the use of penta as a preservative is potential chemical
contamination by polychlorinated dibenzo dioxins (PCDD) and furans !PCDF).
PCDD and PCDF are believed to be acute toxic substances and are suspected of
being carcinogens. The U.S. Environmental Protection Agency restricted the
use of penta effective in 1984 (ERI, 1991) that resulted in a decrease in its
use in many treated wood products.
Copper naphthenate is a "stable chemical compound" that is dissolved in a
petroleum solvent and is deemed to have a "high degree of permanence in .wood*
;AWPA, 1990). Copper naphthenate is generally used as a water repellent on
pallets or exterior decks. According to the AWPA, the concentration of copper
in the preservative solution is between 0.5-1.0 percent by weight for pressure
treated wood, and 2.0 percent by weight for surface treatments.
4.5.3 Water-Borne Preservatives
Water-borne preservatives are solutions of water soluble compounds that
usually contain compounds of ammonia, arsenic, chromium, and zinc. Chromated
copper arsenate is an example of a water-borne preservative. There are three
major grades of CCA, made up of differing fractions of chromium, copper, and
arsenic. Standard formulas include 35 to 65 percent chromium, 15 to 45
percent arsenic, and a constant fraction of copper of approximately 20 percent
(AWPA, 1990; ERI, 1991). other water-borne preservatives include acid copper
chromate (ACC) , anwtoniacal copper arsenate (ACA) , ammoniacal copper zinc
arsenate (ACZA), chromated zinc chloride (CZC), and inorganic boron or sodium
borate (AWPA, 1990.) CCA is used in many residential and commercial
applications. Its use is supported by a 1984 EPA survey of wood preservatives
that emphasized, " . . .wood treated with inorganic arser.i cals is suitable for
most end-uses of lumber, timber and plywood. Inorganic arsenical-treated wood
is clean, odorless, paintable, easy to handle, harmless to plants, and more
durable than other treated wood." EPA also distinguishes between arsenical-
based preservatives and hydrocarbon-based preservatives noting that,
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"...pentachlorophenol and creosote treated lumber, timber, and plywood have
limited uses due to odor, objectionable vapors, and oily, unpaintable
surfaces," (EPA, 1984; ERI, 1991}.
4.6 The Composition of Wood Coatings
A wide variety of coatings and paints may be present in waste wood. Of the
three non-wood materials discussed, wood coatings make up the least proportion
by weight, usually less than 0.1 percent of non-wood additives in waste wood
(ERL, 1990-} , The thickness of coatings depends on the wood product and the
intended use. Coatings range from less than one mil thick to ten mils thick,
!A mil equals l/i000th of an inch.} By definition, coatings that exceed 10
mils are usually referred to as linings or films (Clauser, 1976} , An
alternative measure of paint thickness is supplied by fire toxicity tests,
where paint was applied at a rate of three grams per 100 centimeters. This
application was intended to resemble two coats of paint (ADL, 1988) .
The most common surface coatings are organic coatings including paints,
enamels, stains, varnishes, and lacquers. Organic coatings always consist of
a vehicle and a pigment. The vehicle provides dispersion and film-forming
characteristics that affect texture, spreading, and hardness. The film
forming component of the vehicle binds pigments and other non-volatile
components of the paint (NPCA, 19 89) .
Vehicles can be divided into three groups, based on the type of solvent or
carrier: oil-based vehicles, water-based vehicles, or varnishes. Oil-based
vehicles consist of alkyd, vegetable, linseed, or tung oils combined with
resin, fillers, and pigment. Water-based vehicles contain fine particles of
resin, filler, oil, and pigment. Varnish-based vehicles combine various
resins with either drying or non-drying oils and solvents. Resins used in
oil, water, or varnish vehicles include acrylic, acetate, butyrates, and
polyvinyls (Dagostino, 1983; Clauser, 1976). All vehicles dry or cure through
either evaporation of water or solvents, or through polymerization and
oxidation of oils and resins.
Pigments are chemical agents that are used as coloring, water repellents, fire
retardants, preservatives, and rust inhibitors. Pigment systems consist of
primary pigments, fillers, and secondary organic or inorganic pigments. The
predominant primary pigment used in the paint industry is titanium dioxide.
Fillers are usually talc or calcium carbonate (NPCA, 1989}.
The two classes of secondary pigments are comprised of organic "earth colors"
and inorganic "chemical colors.* Earth colors are chemically stable and
resistant to heat and weather. The more specialized chemical colors are
formed under chemical reaction for specific purposes such as color and
refractive properties.
Chemical colors include metallic-based pigments such as aluminum powder, lead,
and zinc chromate {Clauser, 1976). Before 1940, lead could comprise as much
as 50 percent by weight of dry paint film. In 1955, the American National
Standards Institute adopted a voluntary standard of 1 percent lead content by
weight for interior uses. This standard was codified in 1971 and then lowered
to 0.06 percent in 1976 (ERI, 1991}. Currently, paint containing significant
amounts of lead is most likely present in older buildings or in demolition
waste derived from older buildings.
Other metal-based pigments may contain mercury, titanium, and copper. These
consist of pigments such as arsenic pentasulfide (yellow), copper acetate
(blue-green}, copper ferrocyanide (red-brown), lead chromate (green, yellow,
4-12
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red), and. lead and zinc chromate ("Molybdale Orange" and "Zinc Yellow") {EEL,
1990}.
4.6.1 Major Wood Coating Product Groups
A description of major groups of coatings found in waste wood is provided
below. The description is based both on commonly used product terms' and on
product uses. The product-oriented description is supplemented by a list of
major chemical components of various paints presented in Table 4-5. This
table identifies the Major chemical components of typical wood coatings.
These chemicals are found in various concentrations in the products discussed.
4.6'. 1.1 Paints and Stains
Paints and stains were originally defined as a dispersion of pigment in an
oil-based vehicle. Currently, however, the term paint is often used to
describe a wide variety of organic coatings including stains, varnishes, and
lacquers. Paints and stains are available in a wide range of non-oil,
plastic, alkyd, or acrylic resin bases. According to the NPCA, oil-based
paints account for roughly 30 percent of all paint produced in the U.S.
4.6.1.2 Water-Based Coating#
Water-based coatings contain minute particles of plastic resin and pigment in
a water-based carrier. There are three types of water-based coatings;
emulsions, latexes, and water soluble solutions. Emulsion coatings are
"suspensions in an oil phase in water." Latexes are "dispersions of resins in
water" (Clauser, 1976}. Water soluble coatings are clear, solvent-like
finishes that, unlike latexes and emulsions, contain low molecular weight
resins. Latexes typically contain either acrylic, vinyl, or polyvinyl resins
(Dagostino, 1983). Water-based paints make up 70 percent of architectural
finishes, according to the NPCA.
4.6.1.3 Lacquers
Lacquers are quick-drying paint coatings that use solvents in the vehicle.
The simplest and oldest form of lacquer combined alcohol with lac resin, which
is the basic component of shellac or spirit lacquer. Common synthetic
lacquers now include solutions of cellulose acetate or acetate butyrate, ethyl
or nitro-cellulose, and vinyl resins (Clauser, 1976).
4-6.1.4 Varnishes
Varnishes are paints consisting of "thermoplastic resins and either drying or
non-drying oils" (Clauser, 1976). Varnishes are frequently combined to form
enamels and other types of organic coatings. Varnishes contain either alkyd
or urethane resins,
4.6.1.5 Enamels
Enamels are paints defined as an "intimate dispersion of pigments in a varnish
or a resin vehicle or a combination of both" {Clauser 19761. This group uses
urethane, epoxy, and alkyd resins. Enamels are known for their hard, scratch-
resistant finish and strong coloration.
4.6.1.6 Polyurethanes
Polyurethanes are formulated from several different products to produce a
clear, waterproof, and mar-resistant finish. A main component of polyurethane
4-13
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is tolylene diisocyanate. Polyurethanes are used primarily on floors,
cabinets, and boats.
4.6.2 Proportion of Materials in Paint
In a report completed for the national Paint and Coating Association, a
statistically representative range of concentrations of various components of
paint were selected for flainmability and toxicity testing.
Presented in Table 4-5 are "...factor levels representative of typical paint
products" (ADL, 1998). These factors are based on a database
Table 4-5. Wood coating characteristics.
Typical chemical compounds in paints and coatings®
Alkyd
Alkyd urea
Acrylic
Polyvinyl acetate
Polyur ethane
Polyesters
Nitrocellulose
Ethyleellulose
Butyrate
Vinyl
Epoxy
Melamine
Polystyrene
Styrene-butadiene
Polybasic acid + polyhydric alcohol + monobasic
fatty acid
Oil modified polyester with OF crosslinking
Acrylic acid, methacrylic acid, ester
deriviatives, nitriles and amide derivatives.
-CH.-CHOAc-CH^-CHOAc-
Isocyanates + hydroxy1 containing compounds
Polybasic acids ~ polyhydric alcohols
cellulose + nitric acid
Hydroxy! groups replaced by ethoxy groups in
cellulose
Cellulose acetate butyrate
Vinyl acetate - vinyl chloride copolymer
Bisphenol A + epichlorohydrin -"-sodium hydroxide
Melamine + formaldehyde
( CHj-CHC6Hs-CH2- ) n
(CHJ-CH=CH-CHJ-CHC(iH5-CH2-)n
Typical properties of materials in paints and coatings
Binder (resin)
Primary pigment
Filler
Inorganic secondary pigment
Organic secondary pigment
30% mass for all binder/substrate combinations
Low level;
High level;
Low level:
High level:
Low level:
High level:
Low level;
High level:
0%
30%
0%
20%
0%
a. Prom national Forest Products Association,
b. From Arthur S. Little, 1988.
1989.
collected by Arthur D. Little, Inc. that reflects the range of major surface
coating concentrations. These concentrations were used in flainmability tests.
Note that the table does not show the level of solvent in the formulation
because the solvent evaporates during the curing and drying process.
It is clear from this table that resin content is a primary ingredient {up to
30 percent) in all paint formulations due to its role in the paint vehicle.
Primary pigments, such as titanium dioxide, also comprise up to 30 percent of
a paint solution. Secondary pigments, while useful in paint identification,
are usually less than 5 percent in most paint formulations.
4-14
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Resin content has been identified by the National Paint and Coating
Association as the primary variable in toxicity emissions, due to its high
percentage content in paint formulations. According to a report prepared for
the npca, "...only the film-forming component lor resin) contributes to the
fire toxicity of the product" (NPCA, 1989} ,
Using this criteria, the NPCA identified five classes of surface coatings
based on resin type; acrylic, alkyd, epoxy, vinyl, and urethane. The chemical
components of each of these classes; are described in more detail in Table 4-6,
It is important to note, however, that the five resin classes were developed
for fire toxicity tests. Due to the high temperatures used in controlled
combustion systems, toxicity from resin combustion may not be as important to
air emissions or ash content as metals in paint pigments or other products of
combustion. The table on resin classes is provided to detail chemical
composition only and does not portray the effects of burning painted wood in
wood-fired combustion units.
4,7 Physical and Chemical Contents of Harvested Wood and Six Common Wood
Products
This section identifies and describes the physical and chemical
characteristics of harvested wood as well as six wood products commonly used
throughout the U.S. and Canada. Because the wood products are commonly used,
they are potential sources of waste wood that could potentially be processed
for fuel. In. addition to harvested wood, the wood products described include;
pallets, painted wood, plywood, particleboard, pressure-treated and creosote-
treated wood. The six wood products were selected for this study based on a
variety of factors including their relative frequency and quantity in the
waste stream; their availability to existing and potential fuel markets;
interest by combustion facilities to recover the energy potential of the wood
products; and suspected differences in the combustion characteristics of the
products. Table 4-7, summarizes the key characteristics of each treated wood
product. Information in the text and the table can be used to estimate the
physical and chemical contents of non-wood materials likely to be present in
waste wood.
4.7.1 Harvested Wood
This section focuses on characteristics of harvested wood that are relevant to
its properties when burned. Since harvested wood does not contain, non-wood
materials, this provides a context for understanding potential environmental
impacts of burning harvested wood compared to other waste wood.
Moisture content is a. key factor affecting the heating value of wood burned
for fuel. Moisture content is usually measured and described on the basis of
how much of the contents of the wood is water. For example, freshly cut,
green harvested wood typically has a moisture content of 40 to €0 percent.
Measured on a wet basis, this means that 40 to 60 percent of the wood is
moisture, and that the remainder is wood. Harvested wood that has been dried
by letting it "season," has a moisture content of approximately 20 percent,
or less. Wood that has been kiln dried and then processed into wood products
usually has a moisture content of less than 10 percent (GLRBEP, 1986}.
The energy content of woodfuel is defined in terms of gross and net heating
values. Gross heating value (GHV) is a measure of the energy available from a
pound of wood, taking into account the wood material that is displaced by
water. The net heating value (NKV) represents the usable energy available
after expending energy to evaporate moisture contained in the wood. The
typical gross heating value for freshly cut harvested wood {often referred to
as "green" wood) is approximately 4,800 BTUs per pound. The gross, heating
4-15
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Table 4-6. Description of resin classes".
Acryl i c
Acrylic resins are the film-forming component of this product class.
Acrylic are polymers of acrylic acid, methacrylic acid, and their esters
and amides. Sfcyxene, vinyl toluene, and acrylonitrile are often used as
copolymers in acrylic resins. Individual resin manufacturers may
introduce various comonomers to impact specific properties, such as
improve adhesion and crosslinking.
Alky <3
Alkyd resins are the film-forming component of this product class. Alkyd
resins are polymers of polybasic acids, polyhydric alcohols, and fatty
acids. In a number of products, specific properties are imparted to the
resin through the use of modifying agents. These include rosin,
polymerized resin, phenolic resin, silicone resin, polymer, urethane,
epoxy resins, polymides, styrene, vinyl toluene, methacrylate ester,
aerylate ester, or dicyclopentadiene.
Alkyd resins are often characterized by the amount and type of fatty
acids used in their manufacture; or by the modifier used to impact
specific properties. For example, phenolic modified alkyd, silicon
alkyd, styrenated alkyd, and urethane modified alkyd.
Epoxy
Epoxy resins are the film-forming component of this product class. Epoxy
resins are polymers containing an average of more than one epoxy
(oxirane) group per molecule. The epoxy group is most often attached to
the polymer as a glycidyl ether. Other epoxy resins are prepared by the
oxidation of unsaturated materials or by the incorporation of an epoxy
isomer (i.e., glycidyl methacrylate) into an acrylic copolymer.
Vinyl
Vinyl acetate resins are the film-forming component of this product
class. Vinyl acetate resins include the homopolymers and copolymers of
vinyl acetate along with specialty polymers'such as polyvinyl alcohol and
polyvinylacetal. Vinyl acetate copolymers are formed by copolymerizing
vinyl acetate with other copolymers including vinyl acrylics, alkyd
maleates and fumarates, other vinyl esters, and ethylene. Other commonly
used monomers include hydroxya1ky1 acrylates or acrylic acid.
Urethane
Polyurethane resins are the film-forming component of this product class.
Polyurethane resins are formed through the reaction of isocyanate groups
and with themselves or with compounds containing an active hydrogen such
as water, mono or polyfunctional alcohols, amines, polyesters containing
hydroxy1 groups, polyethers, epoxies, or acrylic polymers. The two main
categories of urethane products are: (1) nonreactive {oxidative or
amine/formaldehyde condensation) crosslinking types, high molecular
weight polymers, and blocked isocyanate polymers and (2) reactive (two-
component) systems moisture cured.
a. From National Paint and Coating Association, March 1989.
4-16
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Table 4-7, Characteristics of common wood product groups.
|Wood product group
Primary non-wood
Amount of
Typical
Primary uses
Comments
1 and types
chemical contents
chemical(s)
moisture
of wood
in wood
content8
product
product
1 A, Pallets and wood
I containers
1. Pallets (hard and
Low levels of pesticides and
<10 ppin
15-20%
Besides shipping
Testing underway for
softwood)
preservatives(pent*, lindane
and handling,
new pallet products
dimethyl copper, or copper
pallets are
with trade names of
naphthenate
chipped for fuel
"Enhanced Wood" which
and animal bedding
use layers of epoxy
2. Skids
Quinolinolata, or copper
and/cr urethane for
naphthenate
washabi 1 ity.. water,
•
and wear resistance.
3. Plywood pallets
Phenolic resins in plywood
2-4%
8-12%
1
4, Glued pallets
Elactoaeric adheaiveo (epoxy)
2-4*
8-12%
Hardwood pallets 1
found mainly in the 1
east., softwood and 1
plywood mainly in the
west,
B. Painted or coated
wood
1. Lead based paint
Lead level depends highly on
1400-20,OOOppm
15-20% exterior
Before 1950, lead as
{demolition wood)
the age of the paint
(before 1950S
6-12% interior
much aa 50% of paint
film. 1955 ANSI
1 2. acrylic baaed paint
acrylic acid, styrene, vinyl
<0.1%
15-20% exterior
standard reduced lead
toluene, nitrilen
6-12% interior
to 1.0% by weight.
i
-------
fable 4-7, Characteristics of common wood product groups (continued).
C, Structural panels
I. Plywood
a. Interior grade
b. Exterior grade
2, Oriented strandboard
'
uera formaldehyde (OF) resins
Phenol formaldehyde (PF)
resins
P£ or PF/isocynate resins
2-4* dry wt.
2-4% dry vt.
2-4%
8-12*
8-12%
Walls, floors,
cabinets
Wall ap.d roof
sheathing
Replacement of
plywood in roofs,
walls, and floors
Kay be surface coated
with fire retardants,
preservatives and I
insecticides, or 1
pressure treated with 1
CCA,
3, Wafer-board
UF or phenolic resins
5-15* IJF, 2.5%
PF, 2 % wax
Wall and roof
sheathing,
interior and
exterior
4. Specialty grades
a. Medium and high
density overlay
panels
b. Luan plywood and
PVC laminate
c. Mr® resistant
PF resins
UF resins, polyvinyl chloride
(PVC)
Salt solutions in core or
borax ruface treatment
4-8%
2.5% UF, 10%
PVC
Highway signs,
exterior panels
Underlayaent for
floors
Where building
codes require it.
D. nonstructural panels
1. Particleboard (It)
grades, 3 density
ranges.
OF resins
5-15* UF
8-12*
Interior uses
May be sealed with
polyurethane
with PVC laminate
2. Medium density
f iberboard
UF re»in» with PVC
UF renin*
4,5% UF, 10%
PVC
8-12%
8-12%
Interior uses
Interior usee
Used for smooth I
finish and painting
3. Hardboard
Phenolic resins
1.5%
Conpoeit I-beans,
underlaynent
Very limited use.
(continued)
-------
Table 4-7, Characteristics of common wood product groups (continued).
$*¦
I
(--i
10
E. Poles, ties, piling,
docking, fencing,
decks
1, CCA solutions
CCA-three grades
1-3%
(a)
Exterior use?
Dominant wood
a, Pressure and
decking, fencing.
preservative
surface traated
posts
Chlorinated phenols
1.2-1.5%
(b)
Utility poles.
2. P«n t ac hiorophenol
laminnated beams,
Restricted use due to
solution
fresh water
industry chang* and
pilings, bridge
concern civet dioxir.
timbers
linkage; not
permitted for
3. creosote solutions
residential uses.
a. Creosote-petroleum
craooote containing 85% PAHs
14% by weight
(a!
Railroad ties.
b. creeosote-coal tar
Creosote containing 05% PAHs
14% by weight
(a)
utility poles,
marina pilings
Lossas after
treatment estimated
c. Creosote coal tar
ro be 20-50% over 10-
'marine grade
15-20%
(a)
25 years; not
-------
value increases dramatically, as the amount of moisture is reduced by
seasoning or kiln drying the wood. Proximate and ultimate analyses are two
tests commonly used to determine basic combustion characteristics of woodfual.
A proximate analysis measures the volatile natter, fixed carbon, and ash
content of wood when combusted. An ultimate analysis measures the amount of
several! common chemical elements in wood such as carbon, hydrogen, oxygen,
nitrogen, and sulfur. Results of ultimate analyses are used to determine the
amount of air needed for efficient combustion and to predict potential
airborne pollutants from combustion {Tillman, 1981). Section 7.6 of this
study discussed in great detail the results of conducting ultimate and
proximate testing of various "clean* wood and waste wood streams.
4.7.2 Pallets
Approximately 2,300 firms in the U.S. produce various sizes and grades of
pallets. Wood pallets and containers are widely used in food, chemical,
manufacturing, and agricultural industries. Pallet manufacturing represents
the second largest use of sawn lumber and the largest use of hardwood lumber
in the U.S. (Smith, 1991}. Western pallet manufacturers rely on softwood
lumber; eastern manufacturers rely on hardwood. Plywood pallets may be used
when dimensional stability is needed and in automated handling systems fNWPA,
1980) ,
Plywood pallet specifications require the use of exterior grade structural
plywood. This plywood usually contains phenol formaldehyde glues.
Pallets may also contain chemical treatments, such as water and insect
repellents, that extend their useful life. A recent study of pallets showed
trace levels of penta, lindane, and dimethyl phthalate (White & McLeod, 1989).
Surface applied water repellents Used in pallet manufacturing include oil
borne soiuticns of copper-8-Quinolinolatie (0.25 percent by weight; and copper
naphthenate (0.5 percent metal). Other preservatives may include borates or
sulfonates (McKally, 8/91; NWPA, 1967),
A new type of pallet is currently being tested with the trademark name
"Enhanced Wood.* Pallets using Enhanced Wood are waterproof and are designed
to last for six years. Enhanced Wood pallets contain elastic epoxy or
polyurethane formulations that are surface applied in a 6 to 8 mil thick coat.
Enhanced Wood has been approved by the U.S. Food and Drug Administration for
direct contact with food (McNally, 1991),
4.7.3 Painted Wood
Characteristics of painted wood depend primarily on the intended use of the
product and the type of paint or coating. Film-forming finishes include
paint, lacquer, varnish, polyurethane, and solid stains.
Penetrating finishes, such as stains and varnishes, are used for protection
against water, insects, and wood decay. Penetrating finishes usually rely on
oil-based stains containing alkyd or
acrylic resins.
Finishes include water repellents, wood preservatives, pigmented stains, and
semi-transparent stains.
Film-forming finishes, either oil- or water-based, are used when strong
coloration and/or water and weather resistance are necessary. Acrylic and
urethane resins are used primarily when durability and color are needed.
4-20
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Besides pigments and fillers, other paint additives may include product-
specific needs such as for pressure-treated wood, wood subject to insect
infestation, or excessive moisture, these additives include ethylene glycol,
preservatives such as copper naphthenate, or fungicides such as lindane.
4,7.4 Plywood
Plywood is defined by the American Plywood Association as "...the original
structural wood panel. It is composed of thin sheets of veneer, or plies,
arranged in layers to form a pan«l. Plywood always has an odd number of
layers, each one consisting of one or more plies, or veneers" (APA, 1990}.
Plywood manufacturing consists of laying veneers in specific patterns,
applying glue and1 hot pressing the layers to form a bonded panel. Coration
plywood thicknesses are 5/16, 3/8, 1/2, and 3/4 inch.
Panels are "performance rated" based on their intended structural use.
Exterior grades will be typically bonded with phenol formaldehyde glues.
Interior grades will contain urea formaldehyde glues. Depending on the
specific manufacturer, plywood contains 2 to 4 percent of either phenol or
urea formaldehyde glue by dry weight. Some exterior grades of plywood may be
treated with acrylic or urethane based paints as well as moisture and insect
resistant preservatives. Interior grades may contain fire retardants.
fypical uses for softwood plywood are for floors, sheathing on walls and
roofs, and concrete forms. Hardwood plywood'is used in furniture, cabinets,
floors, and trim work.
4-7,5 Particlaboard
Particleboard is a non-structural wood panel developed in the 1930's as a way
to recover planer shavings. Ninety-eight percent of particleboard
manufactured in the U.S. is urea-bonded. However, the American National
Standards Institute (ANSI) also defines exterior grade particleboard as a
product that is phenol-bonded (Wardell, 1391). Because particleboard is urea-
bonded, it is sensitive to moisture. Therefore, particleboard is used in
interior cabinets, shelves, stairs, furniture, paneling, or as underlayroent
for floors.
Particleboard contains 5 to 15 percent urea formaldehyde resins by weight. It
is manufactured in ten grades and three density ranges (high, medium, and
low}. The most common grade found in lumber stores is medium density
particleboard. Two special density grades are made for prefabricated homes
and floor underiayments. Higher density grades of particleboard are stronger
and heavier. Particleboard is manufactured from discrete wood particles.
Other non-structural panels, such as fiberboard or hardboard, are manufactured
using an additional processing step which breaks wood down into individual
fibers and which results in products with a smoother finish.
4.7,6 Pressure-Treated Wood
The pressure treatment of wood is defined by the American Wood Preservers'
Institute to be a process "by which chemicals are forced deep into a wood's
cells in a closed hermetically sealed cylinder, or retort under pressures of
100 pounds per square inch or more" (AWPI, 1988). Pressure-treated wood is
used primarily outdoors in docks, fences, decks, bridges, mine shafts,
railroad ties, and landscaping applications.
Pressure-treated wood may be treated with one of three major wood
preservatives {listed below) in two major grades. One grade is for
aboveground uses such as sill plates, decks, or fences. The other grade is
for ground contact with soil or fresh water (AWPI, 1988). Standards for both
4-21
-------
grades as well as for specialty grades, such as salt water exposure, are
specified by the American Wood-Preservers1 Association.
Wood pressure treated with creosote is used primarily for railroad ties,
utility poles, highway bridges, and marine uses. It is not recommended for
interior uses. A specialty creosote- treated product intended for marine uses
may contain an insecticide (such as chlropyrifos) used to repel specific
marine borers that are found in semi-tropic coastal waters.
Wood pressure treated with pentachlorophenol is widely used to manufacture
poles and pilings. Due to the difficulty of pressure treating very long
poles, penta is frequently applied by soaking in thermal baths. Before the
development of inorganic arsenicals, penta was used extensively in exterior
preservation. However, two major corporations recently stopped manufacturing
penta. The remaining manufacturers of penta sell almost exclusively to
utility pole manufacturers. Glue- laminated beans in commercial structures,
such as sports arenas or shopping centers, may also contain penta. However,
penta is not recommended for interior uses. Wood pressure treated with
inorganic arsenicals, such as CCA, is widely used for treating exterior
dimensional lumber because CCA is chemicaliy more stable and permanent than
hydrocarbon preservatives, and CCA does not emit fumes. - CCA-treated wood is
used in decks, fences, landscaping, and playgrounds. It is also used for
interior applications where exposure to moisture, potential infestation, or
decay nay be a problem (AWPI, 1988).
4.7.7 Craosote-T»afced Wood
Creosote treatment may take place either through pressure treatment or by a
process known as thermal treatment. Under thermal treatment 51 ...the material
to be treated is heated for several hours in an open tank of pentachlorophenol
or creosote preservative, then quickly submerged in a cold solution for
several hours...the thermal process resembles a vacuum process in
principle..." (AWPI, 1988). Standards for creosote formulas and retention in
wood are specified by the AWPA. Creosote- treated wood or logs are used in
residential interiors, log homes, outdoor furniture, and animal pens. Prior
to I960, most utility poles were treated with creosote solutions. Since then,
the primary treatment method has used pentachlorophenol independently or with
other creosote solutions (Srennan, 13 91). Due to vapors, creosote-treated
wood may be sealed with coal tar pitch, urethane, epoxy, or shellac (AWPI,
1988) .
4.8 Bibliography - Chapter 4.0
American Plywood Association. Performance Rated Panels. Tacoraa, WA. Revised
September 1990.
American Plywood Association and the National Wooden Pallet Association.
Specifications for Softwood Plywood Pallets. Tacoma, WA., Washington D.C.
February 1980.
American Wood-Preservers Association. American Wood-Preservers' Association:
Standards 1990. Stevensville, MD. July 1990.
American Wood Preservers Institute. Questions and Answers about Pressure
treated Wood. Vienna, VA. March 1988.
Baker, Andrew J. Corrosion of Metals in Preservative-Treated Wood. Forest
Products Research Society. Madison, WI. October 1987.
4-22
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Clauser, Henry R. Encyclopedia/Handbook of Materials. Parts andFinishes.
Technomic Publishing Co., Inc. Westport, CT. 1976.
C.T. Donovan Associates, Inc. Recycling Construction andDemolition Wastein
Vermont. Vermont Agency of Natural Resources, Department of Environmental
Conservation, Solid Waste Management Division. Montpelier, VT. December
1990 .
Dagostino, Frank R. Materials-of Conat£H££ifla. Reston Publishing Company,
Inc. Reston, VT. 1982.
Emery, John A., Ph.D., Manager, Environmental Affairs, American Plywood
Association, personal communication, August, 1391.
Environmental Risk Limited. The Composition of Recycled Wood Fuel and Its
Environmental Permitting Implications. Bloomfield, Cf. September 1990.
Environmental Risk Limited and C.T. Donovan Associates, Inc. Mood Products In
the Waste Stream: Characterization and Emission Testing .Protocol Developaent.
Technical and Management Proposal Submitted to: The New York State Energy
Research and Development Authority. Albany, NY. September 1990.
Great Lakes Regional Biomass Energy Program. Industrial/ Commercial Wood
Energy Conversion. Council of Great Lakes Governors. Madison, WT. 1986.
Hsu, Or. W.E. Advanced Wood-Fiber Composites. Proceedings of the Workshop on
Wood-Plastic Composites. Canadian Forestry Service and the Alberta Forest
Service. Edmonton, Alberta. February 1988.
Kamrin, Michael A. Toxicology; A Primer on Toxicology Principles and
Applications. Lewis Publishers, inc. Chelsea, Ml. 1988.
K.C. Shen Technology Int. Ltd. and Forintek Canada Corp. Bioresin for Bonding
Wood Composite Boards. Canadian Forestry Service and the Alberta Forest
Service. Ottawa, Ontario. November 1989.
Little, Arthur D. Toxicity of Combustion Products From Paints Applied To
Realistic Substrates. National Paint and Coatings Association. Washington,
D.C. April 1988.
Mickl«wrj.ght, James T. Wood Preservation Statistics, ..19.81. American Wood
Preservers Institute. Vienna, VA. January 1990.
Milford, Jana B., Vicki S. Nikolaidis, Madhurima Das. After the Wrecking
Ball; How Land Disposal and Burning of Demolition Wood Affect the
Environment. University of Connecticut, Storrs, CT. February 1991.
Miller Paint Company. Material Safety Data Sheets. Portland, OR. March
1991,
Misner, Michael. "Cutting Into Wood Waste Markets." Waste Age. Washington
D.C. August 1991.
National Forest Products Association. Request For Approval of Classes.
Washington, D.C. June 1989.
National Paint & Coatings Association. "New York State Regulations For
Combustion Toxicity Testing." Safety and Health Bulletin No. 59. Washington,
D.C. November, 1989.
4-23
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National Paint & Coatings Association. "FlananaMlity of Paint Study.
Technical Division Scientific Circular." Washington,, D.C. May 1974.
National Pallet & Container Association. "Wood Pallet Containers and
Container Systems," Washington, D.C- 1967.
Smith, Paul M. "The Washington State Wood Pallet Industry." Forest Products
Journal, Volume 41, Number 5. Madison, WI. May 1991.
Structural Board Association, generic Material....Safety Data..Sheet.
Willowdale, Ontario. February 1989.
Structural Board Association. OSB and Waferboard in Wood Frame Construction.
Willowdale, Ontario. tl.S Edition 1991/92.
Tillman, David A., Amadeo J. Rossi, William D. Kitto. Wood Combustion
Principles. Processes, andEconomics. Envirosphere Company. Bellevue, WA.
1981
Wardell, Charles. "Composition Panels. OSB, particleboard, MFD and
hardboard: what they are and what they do." Fine Homebuilding. Newton,
Cf. April/May 1991.
White, Marshall S., John A. McLeod III. "Properties of shredded wood
pallets." Forest Products Journal, Volume 39, Number 6. Madison, WI. June
1989.
4-24
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5.0 WASTE WOOD PROCESSING FACILITIES
5.1 Introduction
This chapter describes facilities that collect, sort, and process waste wood
for fuel. Key steps and their sequence used during processing are explained,
Information is provided on the design, operation, and capabilities of specific
types of equipment commonly used by processors. The chapter is organized into
five sect ions.
Section 5.2 discusses the ways in which waste wood processors can improve
solid waste management in municipalities, states, and provinces. This is
important because most waste wood received by processors would usually be
discarded, either legally or illegally.
Section 5.3 describes the major characteristics of four types of facilities
that process waste wood for fuel. Mobile facilities are distinguished from
stationary facilities. Facilities that only process wood are distinguished
from facilities that process multiple types of waste, such as construction and
demolition debris containing rabble, metal, glass, and wood.
Section 5.4 describes the basic steps included in a waste wood processing
line, and the sequence in which they occur. Information is provided about
facilities that receive wood that is presorted from other types of waste.
Information is also provided on facilities that receive wood that is
commingled with other waste, such as construction and demolition debris.
Factors that affect the selection of processing equipment are discussed, as
well as factors that affect the ability to remove non-wood materials from the
waste. Techniques used to sort, separate, and process both treated and
untreated waste wood are explained.
Section S.5 describes the equipment used in each step of a processing line,
and explains the overall capabilities of the equipment. Information is
provided on how waste wood with relatively small amounts of non-wood materials
or contaminants is processed to meet air and ash standards of combustion
facilities. Information is also provided on how wood with significant amounts
of non-wood contaminants is handled, screened, and processed.
Section 5.6 provides a summary of waste wood facilities researched for this
study. A table is included that lists major facilities in the study area.
Another table notes the types of equipment used at eight facilities, five of
which are in the study area.
Section 5.7 includes case studies of two waste wood processing facilities in
the study area. The facilities were visited as part of the research for this
study. The case studies include information about the equipment used as well
as solid waste and waste wood management issues affecting the area where the
facility is located.
Section 5.8 describes the role of tipping fees and disposal costs in waste
wood processing for fuel. Tipping fees among several solid waste management
facilit ies in the study area are compared. Factors affecting disposal costs
for waste wood, particularly wood generated from construction and demolition
activities are discussed.
5.1.1 Key Questions Regarding Waste Mood Processing
• What regulatory and economic issues affect the ability of processors to
use wood from the waste stream?
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• What types and sizes of facilities process waste wood for use as a fuel?
• What are the primary types of technologies used to prepare wood for fuel?
• What types of non-wood materials can successfuliy be removed from waste
wood while processing the material for use as fuel?
5.1-2 ley Findings
• The decision to operate a waste wood processing facility is influenced by
many factors. These include: the economic and regulatory climate that
affects wood that may be "disposed" of at processing facilities; the way
in which recycling and solid waste management authorities permit a
processing facility; and, the status and requirements of markets that use
processed waste wood for fuel or other uses.
• The four major types of waste wood processing facilities are defined by
their size and the technology used. Three types of facilities (listed
from smallest to largest) usually operate as physically independent:
facilities. On-site processing facilities are found adjacent to
corabustion units, and vary by size and requirements of the combustion
technology being served,
- Mobile waste wood processors
- Stationary wood-only processors;
- Stationary multi waste processors, and;
- On-site processors located at combustion facilities.
• Processing technologies continue to evolve in response to market demand
for certain quality wood fuels, and economic incentives facing the
recycling industry. In general, new metal recovery, screening, and
washing technologies have improved the ability of processors to prepare
waste wood that meets fuel specifications.
• Despite advances in processing technology, a key step in controlling the
level of contaminants in wood fuel is through inspection and enforcement
procedures "at the gate* of a processing facility. Several techniques
are available for controlling unacceptable waste wood from entering a
processing facility, including the use of contracts and economic
penalties.
• When waste wood is accepted for processing, cleaning equipment designed
specifically to detect and remove foreign metal,dirt, and other attached
debris is capable of high removal efficiencies. Chemicals, stains, or
preservatives that impregnate wood are usually unable to be removed
during mechanical processing.
5.2 How Waste Wood Processors both Affect and are Affected by Solid Waste
Management Issues
Substantial amounts of waste wood are generated by households, businesses, and
industries in the U.S. and Canada. With the exception of mill residue
generated by wood products industries, until the 1980*s, most waste wood was
disposed of either in permitted disposal facilities or through illegal
backyard dumping and on-site burial. During the past decade, however, a
variety of waste wood processing facilities have been developed stimulated by
escalating tipping fees at other solid waste facilities, and by the
availability of markets for products recovered from, wood.
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To date, most major waste wood processing facilities are privately owned. The
facilities -usually complement, rather than duplicate, existing solid waste
management and disposal services. In general, waste wood processors improve
the management of solid waste by accepting waste at competitive tipping fees,
and by creating new reuse and recycling capabilities. Processors produce a
variety of products that have market value, including fuel, potting soil,
landscaping mulch, animal bedding, sludge stabilizer, compost amendment, and
manufactured building products, among others,
5.2.1 Major Factors Affecting Processors
A variety of factors affect waste wood processing facilities. Processing
facilities require successful operation of two distinct components. One
component involves obtaining sufficient supplies of waste wood. This is
partially a function of being able to charge tipping fees for waste delivered
to the processing facility that are competitive with, or lesser than, fees
charged at other disposal facilities. The second component involves securing
a reliable demand, and suitable price, for products recovered from the wood.
In some locations, there is an adequate supply of wood needing "disposal," but
there are insufficient end-use markets. In other locations, the reverse is
true.
Specific factors affecting the role and overall impact of waste wood
processors in solid waste management vary. In some locations, a large demand
for end products has a significant impact on processors. An example is
California, where nearly 1,000 MM of power are produced (as of 1991) from 70
wood-fired facilities. This relatively large amount of power generation has
resulted in substantial demand for wood fuel and increasing competition for
waste wood by processors. In other locations, solid waste policies have a
significant impact on waste wood processors. An example is Florida, where
publicly owned landfills are banned from accepting wood for disposal.
Municipal and private haulers are actively seeking new disposal, reuse, or
recycling opportunities for waste wood; however, existing end-use markets are
limited, especially for fuel.
Major factors affecting waste wood processors includes existing solid waste
and recycling programs, policies, and regulations,- the availability of waste
wood for processing; the extent of end-use markets; and specifications for end
products. These factors affect a processor's selection of equipment,
determination of the appropriate capacity of a facility, and facility
location. These factors are discussed in the following text.
5.2.2 Policy and Regulatory Factors
Federal, state, provincial, and local solid waste and recycling programs,
policies, and regulations affect waste wood processing facilities in many
ways. Examples are noted below.
• Solid waste management and recycling policies and programs that
divert waste wood from landfills, and that encourage the reuse
and recycling of the material can stimulate waste wood
processing. Examples of such policies and programs include
subsidies for the source separation of waste wood and tax
incentives for processing equipment (Yvars, 1991} , These
approaches provide incentives for separating wood from other
waste, and increase the availability of waste wood for reuse and
recycling.
• Policies and regulations that establish guidelines for
permitting waste wood processing facilities can clarify and
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facilitate the development stage for a processor. In some
states/provinces, the guidelines are unclear, untested, or
developed on a case-by-case basis,
• Solid waste authorities that purchase waste wood processing
equipment or help fund facilities can stimulate diversion of
wood from landfills, and thereby extend their existing capacity
for other wastes. An example is the purchase of a mobile tub
grinder by a county solid waste district that is used by all
municipalities in the district {Cech, 1991). This provides the
infrastructure for processing waste wood obtained from public
lands and municipal pick-up services.
5.2.3 Factors Affecting Waste Wood Availability
A variety of factors affect the availability of waste wood for
processing. These are noted below,
• Bans or penalties on the disposal of waste wood in landfills are
increasingly being used by solid waste authorities to maximize
the remaining capacity of existing landfills (Moore, 1991} due
to the high cost of siting, permitting, and building new
landfills. The bans can result in short- or long-term surpluses
in waste wood, and can stimulate investments in processing
facilities.
• Tipping fees charged for "disposing" of waste wood at processing
facilities are usually less than tipping fees charged at other
disposal facilities, such as landfills and refuse-to-«nergy
plants. This provides economic incentives to waste generators
and haulers to provide waste wood to the processor, rather than
to "dispose" of it at other facilities.
• The availability of other waste wood disposal options, such as
on-site burning, burying, composting, or illegal dumping,
affects the availability of waste wood for processing
facilities. If other disposal options are readily available and
cost-effective, it .may be difficult for a processing facility to
obtain adequate supplies of waste wood. *
• Most processors have specifications for the types of wood
accepted at their facility. Unless tipping fees at the facility
are significantly lower than other facilities tor if on-site
burning and other practices are allowed), it may not be
convenient for generators and haulers to separate and sort wood
to meet the specifications.
• In order to guarantee a stable, cost-effective supply of wood
that meets their fuel specifications, wood-fired power plants
are increasingly investing in or developing processing
facilities that prepare fuel specifically for their facility
(Allen, 1991; Fitzgerald, 1991), In some cases, power plant
developers are investing in existing processing facilities that
were originally independently owned ^Fitzgerald, 1991).
5.2.4 Factors Affecting End-Use Markets
Many processors produce multiple products including, but not limited to, fuel.
This allows the processor to supply material to more than one end-use market.
At some facilities, prices paid for waste wood processed into fuel are lower
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than prices paid for waste wood processed into potting soil, landscaping
mulch, or other products {Remington, 1991). The ability to supply higher
priced end-use markets can increase the economic feasibility of also
processing and supplying lower priced fuel. Several aspects of end-use
markets that affect waste wood processors are noted below.
• The availability of reliable end-use markets for processed wood
is essential for the successful operation of a processing
facility (Mitt lamar., 1991} . In addition, the availability of
multiple markets can offset seasonal fluctuations in demand for
wood. Examples include the substantial variation in demand for
wood by dispatchable power plants that only produce power when
instructed to by regional power authorities. Another example is
seasonal landscaping markets in northern climates.
• Market premiums may be paid for specific grades of processed
wood, especially if there is strong competition for processed
wood overall. The premium price paid will depend on specific
wood product characteristics, such as moisture content, dirt
content, chemical content, particle size, or heating value
{Karakesh, 19915 . Premium prices are preferred by processors,
particularly if they have modified their facility specifically
to produce a certain quality product.
5.2.5 Factors Affecting Treated Waste Wood Processing
Different equipment and manual techniques are used at facilities that receive
and process significant amounts of treated waste wood than at facilities that
do not. The willingness of processors to purchase appropriate equipment for
handling and cleaning treated waste wood is a function of a variety of
regulatory and economic issues. Specifications for end-use products usually
determine the types and mixture of waste wood accepted and processed at a
facility.
5,3 Types of Waste Wood Processing Facilities
In general, processors whose primary supply of wood is from municipal,
commercial, or industrial sources use substantially different equipment and
manual techniques than those whose primary supply is harvested waste produced
by forestry ana site conversion activities because waste wood from municipal,
commercial, and industrial sources is more variable in size, physical
contents, and chemical composition, than harvested wood. In addition, the wood
may be commingled with other waste. Depending on the equipment and techniques
used at a processing facility, other waste may need to be separated from the
wood before it is processed.
There are four types of facilities that process waste wood into fuel {and
other products), including;
• Mobile waste wood processors;
• Stationary wood-only processors;
• Stationary multi-waste processors,* and
• On-site processors at combustion facilities.
There are many sizes, or capacities, of processing facilities and there is not
always a correlation between the type of facility and its capacity. In this
report;
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• •Small* processors are defined as facilities that generally have a
capacity to process less than 50 tons per day of wood, or less than
15,000 tons per year. However, small facilities are usually mobile
processors consisting of a tub grinder or hammermill which can be hauled
by pick-up truck.
• "Medium" facilities usually have the capacity to process 50 to 200 tons
per day, or 15 to 60,000 tons per year and usually include large mobile
equipment transported on flatbed trailer(s), stationary wood-only
facilities, or processors that operate on-site at a combustion plant.
• "Large" facilities have the capacity to process more than 200 tons per
¦ day, or more than 60,000 tons per year. Large facilities usually include
the largest wood-only processors and most multi-waste processors. Large
facilities are most likely to handle significant volumes of treated wood
because they have economies of scale that allow for the purchase and use
of more expensive processing equipment to sort and remove contaminants
from treated waste wood.
Table 5-1 summarizes key characteristics of the different types of processing
facilities. Information in the table is discussed in wore detail below.
5.3,1 Mobile Waste Wood Processors
During the past ten years, mobile waste wood chippers and grinders have become
available in various sizes that can be hauled from site to site. Some mobile
equipment is designed to process only harvested wood. Other mobile equipment
can process multiple types of harvested, municipal, commercial, and industrial
waste wood. Other mobile equipment is designed to process waste wood that is
commingled with other materials, such as rubble, metal, and glass found in
construction and demolition debris. Mobile facilities usually charge a fee
for processing and removing the material from a site. Earlier versions of the
equipment were designed primarily for volume reduction. More recent versions
are also designed to recover materials that have market value. Mobile waste
wood processors are found throughout the study area. They range from home- and
garden-scale chippers for yard, brush, and urban forestry uses, to
commercial-scale tub grinders and shredders. Mobile processors are used at
construction sites, during urban forestry programs, for maintaining utility
rights-of-way, or to process wood gathered during municipal pick-up services.
Mobile processors handle waste wood in different ways depending on: the types
of materials being processed; solid waste regulations that affect reuse,
recycling, and disposal; and the availability of end-use markets including;
• Leaving wood on-site that has been "processed" simply to reduce
the volume. The wood is then either buried or burned in open
piles. Depending on the location# this is most common for site
conversion wood, construction projects in rural areas, and some
agricultural residue.
• Hauling the wood to a landfill, compost facility, or
refuse-to-energy plant.
• Hauling the wood to a wood-only or multi-waste processor for
further cleaning and processing.
• Hauling the wood directly to a combustion facility, if the wood
is suitable for combustion with minimal or no further
processing.
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Table 5-1. Types of waste wood processing facilities.
Typ« of
Facility
Typical Bquivownt
tjs»a
Material* Procnttd
Typical
Quantity
Processed
Markets Served
Nobila-
was ta vood
small hammemills
Tab grinders
Clean wast# wood
from logging,
landclearing, or
landscaping !for
transport)
s 500
tons/day
landscaping,
compost, mulch,
fuel, *nd
landfill cover
Mobile-
construction
and demolition
debris
Heavy duty
impactor, crusher,
or shredder. Primary
screening or metal
removal possible.
Demolition waste
wood, scrap metal,
concrete, glass,
brick, rock. audi
rubble (for
transport)
s 1,000
tons/day
(snixadj
Typically do not
serve markets
directly.
Material is
reatavad for
further
processing or
recycling. Waste
wood typically
requires further
processing unless
used for landfill
cover.
Stat, ionary-
wood only
Inspection,
weighing, sorting.
Usually up to two
processing lines.
Tub
gr inder I hammeraill.
Primary screening
and sorting.
Secondary screening
and sorting. Ferrous
and nonferrous metal
removal. Fuel
storage and
conveying.
Clean harvested
wood. Construction
and demolition wood.
Some treated wood.
Wood with tarpaper,
shingles, or sheet
metal attached.
Industrial pallets,
spools, shipping
dunnage.
s 3,000
tons/w««)c
Pual,
landscaping,
compost, mulch,
bulking agent for
sludge, potting
soil, cement
additive, wood
fiber for
manufactured
building
products.
Stationary-
wulti-waste
Inspection,
weighing, sorting.
Usually up to three
processing lines.
Heavy duty impact or,
crusher, or
shredder. Tub
grinder/hammer-mi 11.
Primary screening
and sorting. Ferrous
and iionferrous metal
removal. Fuel
storage and
conveying.
Clean halves ted
wood. Construction
and demolition wood.
Some treated wood.
Wood with tarpaper,
shingles, or sheet
metal attached.
Industrial pallets,
spools, shipping
dunnage. Hen-wood
materials include:
metal, glass, brick,
gypsum, concrete,
wire, tubing,
plastic, and rock.
s 10,000
tone/weak
(mixad)
Waste wcod is
typical sold to
either fuel or
mulch markets.
Non-wood
materials sold to
other markets.
Qn-si te
combustion
facility
Inspection
procedures.
Hairufierra.xll hoggers.
Secondary screening,
sorting, and ferrous
metal removal. Fuel
storage and
conveying
Clean harvested,
construction, and
demolition wood.
Primary and
secondary ttd.ll
residues.
s 1,000
tons/woek
Combustion
facility: may use
wood as primary
fuel or may be
commingled with
other Euels as a
secondary fuel.
Small, mobile processors are primarily designed to chip branches,
brush, saplings, logging slash, pallets, and wooden shipping
containers that are fairly uniform in size. Mobile units are often
sized to process wood that is up to, but not more than, six inches
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thick. They are not usually designed to process waste wood that
varies widely in size and shape. In addition, small mobile
processors usually do not have the capacity to separate wood from
other waste materials, or to reduce or remove potential contaminants
in treated waste wood.
Larger mobile units may be able to process wood that varies
significantly in size and shape, such as stumps, construction wood,
or demolition wood. This will depend on the equipment's horsepower,
torque, and the ability to adjust hammers to various sizes and shapes
of material. Large mobile processors may have magnets that can
separate ferrous metal from wood. They are sometimes used in
conjunction with mobile screening equipment. The screening
equipment, such as rotary trommel8, may be hauled on a separate
trailer and then attached to the haunmermill at the site.
5.3.2 Stationary Wood-Only Processors
In addition to mobile facilities, a variety of stationary waste wood
processing facilities are in operation that process and sell
recovered waste wood. During the 1980'a, an increasing number of
stationary facilities were developed in the U.S. and Canada,
particularly in or near urban areas. This was stimulated by new
markets for recovered wood such as fuel and new regulatory
constraints on the land disposal of waste wood (Moore, 1992). ,
Some stationary facilities are also involved in hauling waste,
running a transfer station, operating a landfill, or managing a wood
combustion facility. Others are "stand-alone" facilities not
otherwise involved in. the solid waste or power generation industries.
Some stationary facilities only process waste wood. Referred to in
this report as "wood-only" processors, these facilities process wood
from many different sources, such as harvested site conversion wood,
Mill residue, pallets, construction and demolition wood, and other
waste wood produced by household, businesses, and industries. The
types of wood processed may include clean harvested wood, painted
wood, wood containing glues and resins, and/or wood treated with
preservatives or other chemicals.
Numerous stationary wood-only processors are located throughout the
study area. Although the facilities only accept wood tor processing,
some are similar to raulti-waste facilities in their efforts to secure
multiple end-use markets for different types and grades of processed
wood. The markets include fuel chips with different moisture
contents, mulch chips that may be colored or sized for specific uses
or slightly composted to add moisture, and small particle "fines" for
fertilizer. A blended fertilizer or "potting soil" may also be
produced from a combination of wood fines and dirt removed during
processing {Winzinger, 1991). Stationary wood-only processors sell
processed wood for animal bedding, landfill cover, groundcover for
horsetracks or animal arenas, and raw material for manufactured wood
products, such as flakeboard and chipboard (Mittleman, 1991).
The ownership of stationary wood-only facilities varies. Most large
facilities are privately owned. However, a growing number of
municipalities and solid waste districts are investing in mobile or
stationary processing equipment. The public facilities are being
developed in response to mandated recycling goals, and to provide
chips for landfill cover, compost projects, or sludge produced by
wastewater treatment facilities.
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5.3.3 Stationary Haiti-Wast® Processors
Other stationary facilities process materials in addition to wood,
such as concrete, gypsum, rock, brick, metal, and glass. These
"multi-waste" facilities may accept materials in commingled loads, or
they may require a certain level of separation, prior to delivery to
the processor. Waste is supplied by municipal and private haulers,
drive-in residential sources, and C&D contractors. Once at the site,
the waste may be processed in its commingled form, or materials such
as wood may be separated before being processed depending on the
type of equipment used, manual sorting techniques used, and
specifications for the end-use product{s).
Tipping fees are usually charged by stationary multi-waste
processors. The tipping fees are often lower than other disposal
facilities in the area, such as landfills and refuse-to-energy
plants. This provides a financial incentive for waste generators and
haulers to "dispose" of their material at the processor, rather than
at another solid waste facility. In addition, some processors charge
lower tipping fees for wood that is segregated from other waste and
presorted according to the processor's specifications, before being
delivered to the facility. This provides a financial incentive for
waste generators and haulers to provide the specific type of material
wanted by the processor. A processor's specifications for material
accepted at the facility are a function of specifications required by
end users, corabined with the technical capabilities of equipment used
by the processor.
Stationary multi-waste processing facilities are common in the study
area, especially in major metropolitan areas. The facilities may be
developed as part of an integrated source separation and recycling
program. Or, they may be developed as a result of increasing
disposal costs at other solid waste facilities and the availability
of end-use markets for recycled materials. Multi-waste facilities
may consist of comprehensive, turnkey demolition processing systems
built by a single manufacturer (Hawker, 1991}. Or, they may consist
of equipment from many different manufacturers that is configured in
a way unique to each facility {Clark, 1991}.
Multi-waste facilities operate as either stand-alone recycling
centers, or as part of (or adjacent to} separation, volume reduction,
and recovery efforts at landfills. In some states, such as
California and New York, landfill operators are, or will soon be,
required to prohibit designated "recyclable* materials such as wood
from disposal in MSW landfills {Norman, 1991). This has prompted
development of other forms of waste handling and processing at
existing solid waste facilities.
5.3.4 On-Site Processors at Combustion Facilities
A fourth category of waste wood processors are facilities that
operate at, or adjacent to, a wood-fired facility. Both small
manufacturing facilities that burn wood, and relatively large
stand alone power plants own and operate waste wood processing
equipment. For some facilities, such as a plywood manufacturer, the
processing equipment used is a hammermlll or hog that chips strips of
plywood trim for use in the plant's boiler.
Other facilities use a more substantial and specialized processing
system. This level of processing is most common at stand-alone
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wood-fired power plants. The systems are usually designed as quality
control mechanisms for fuel burned on-site. The need for the
processing system is based on the physical and chemical contents of
waste wood received, and on the importance of ensuring a consistent
grade of fuel for the combustion unit. Many wood-fired power plants
have on-site screening systems that provide a final level of dirt
removal, metal removal, and/or sizing of the fuel, prior to
combustion fJoseph, 1991}. This additional fuel preparation is
needed to minimize wear on the handling equipment, maintain
combustion performance, and minimize corrosion of combustion and
pollution control equipment. There are three potential disincentives
for using waste wood processing equipment at a combustion site.
First, there are substantial additional costs for the equipment,
training, labor, maintenance, and space required. Second, in many
states a variety of complicated (and from a developer's perspective,
timely and costly) regulatory reviews are required, as a result of
being both a solid waste management for materials recovery facility)
and a combustion facility. Third, for facilities that process
substantial amounts of treated wood, it may be necessary to secure a
disposal site for residuals produced during processing {Karakesh,
1991).
5.4 Processing Lines at Wood-only and Multi-waste Facilities
Wood-only and multi-waste processing facilities recover waste wood
for processing in several ways. Wood may arrive in a mixed
demolition load containing concrete, rock, sheetrock, insulation, and
other materials. Or, it may arrive as mixed waste wood containing
both clean and treated waste wood. Or, the facility may use tipping
fee incentives to encourage the delivery of waste wood that is
presorted, prior to delivery. The sorting may involve separating
wood from other waste, or separating different types of wood based on
its physical and
chemical composition,
5.4,1 How Processors Define *Clean" and •treated" Waste Mood
The precise definition of what constitutes "clean" and "treated"
waste wood varies among states and provinces, and among individual
facilities, Most processors consider pallets, plywood, spools and
dunnage, furniture scraps, mill residue, particleboard, painted wood,
and demolition wood clean and acceptable for processing into fuel.
On the other hand, most processors consider wood that is treated with
creosote, penta, or CCA to be "treated" wood, that may or may not be
acceptable for fuel depending on the end user.
In some states, processors may define "clean" wood and "treated" wood
differently than environmental officials. This is most common for
plywood, particleboard or other wood containing glues and resins,
painted, and demolition wood. Most processors consider this wood
acceptable for processing, and acceptable as part of the mix of wood
processed for fuel although the wood may be processed using different
equipment and a different processing line than clean wood. However,
regulators may not agree that these types of wood are acceptable for
processing and use as fuel.
Regulators sometimes use the term "demolition* wood interchangeably
with the term "treated" wood to describe potentially dirty wood that
may be unacceptable for processing and use for fuel. Although
processors may handle and process demolition wood differently than
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other types of clean wood, they usually consider it as wood with the
potential to be cleaned during processing. Demolition wood is
frequently included under a broad definition of clean wood in
specifications that describe materials that are accepted at the gate.
Processors are confident that demolition wood, less the portion that
is treated wood, can be sufficiently cleaned during processing so it
can be reused. Their major priorities when processing fuel are to
remove dirt, sand, metals, and non-wood chemicals because these
materials can affect combustion performance, air emissions, ash
contents, and maintenance requirements of combustion equipment at
wood-fired facilities. There are examples of written specifications
for waste wood delivered to two processing facilities in the study
area in Appendix D.
5.4,2 Key Steps in a Processing Lin©
The first step at. processing facilities is the delivery, inspection,
and acceptance of waste wood. To maintain quality control, almost
all processing facilities require visual inspection of a. load, before
it is unloaded at the processing site. If load is unacceptable, it
is rejected and sent away.
When a load is accepted and unloaded, a variety of mechanical and/or
manual sorting activities are conducted that provide the opportunity
to further inspect the material.
Following the sorting and inspection procedures, waste wood and other
debris is ground for handling and additional separation. Large
multi-waste facilities use heavy duty C&D shredders or impact
machines for the initial volume reduction {between 5:1 and 8:1} of
bulky wastes, before additional processing. These are 600 to 800
horsepower (HP) machines capable of grinding a range of materials,
such as wood, scrap metal, concrete, glass, ana brick..
At wood-only facilities, initial volume reduction and primary sizing
is accomplished with either a hammermill "hogger" or a tub grinder.
These machines have smaller horsepower ranges than C&D shredders
usually from 60 to 300 HP ana are designed to only accept wood only.
Although dirt, rock, bits of rubble, and small scraps of metal
routinely pass through tub grinders and hammermills, facility
operators strive to minimize the amount of non-wood material due to
the extra equipment wear and maintenance caused by these materials.
Following initial grinding, a combination of screening, sorting, and
cleaning technologies are used before waste wood is ground and sized
for a final product. These technologies include float tanks, manual
picking stations, rotary trommel screens, air classifiers, and disk
scalping screens. A combination of at least two or more of these
technologies is used to separate wood from other debris. These
technologies are described in more detail in Section 5.4,
In newer turnkey systems, clean waste wood may be fed into a
processing line at the point where dirtier wood has completed primary
cleaning and screening stages. At this point, both types of waste
wood enter the final sizing and screening portion of the processing
line and are commingled as a final product. At other facilities,
independent processing lines may be used to produce specific
products. Compost and mulch chips from harvested wood waste, for
example, are sometimes handled separately from wood separated from
the waste stream (Zanker, 1991) .
5-11
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Overall, certain techniques and procedures are fairly consistent
among processing facilities, especially inspection, presorting
procedures, primary grinding equipment, the use of metal removal
equipment, selection of screening devices, and fuel storage systems.
Figure 5-1 illustrates a waste wood processing line, from initial
inspection to the final preparation of recovered products. The
actual system used varies among processors, depending on the type of
waste wood accepted and end-use products produced.
5.4.3 Factors Affecting Renewal of Ion-Wood Material
Four factors affect the ability of processing equipment to remove
non-wood contaminants from waste wood including:
• Amount of redundancy built into the processing line(s);
• Period of time a specific volume of waste wood spends at each
step in the processing line that cleans the wood in some way
{referred to as "cleaning stations" in this report};
• Composition of the material when it arrives at each cleaning
station; and
• Rated design capacity of a given piece of processing equipment,
compared to the amount'and rate of wood handled by the equipment
(Groscurth, 199 2! .
These factors are interdependent. For example, removal efficiency depends
partly on the rate of throughput of material. It also depends on the amount
of non-wood material already separated before the wood arrives at a particular
point in the processing line.
Efficient separation of non-wood material generally results from a combination
of: system design, system redundancy, and operating techniques. At both
wood-only and multi-waste processing facilities, this is accomplished by
applying technologies that sort specific types and sizes of non-wood material,
and that replicate the same screening or sorting procedure at multiple
locations in the processing line.
5.4.3.1 Redundancy
One processing facility uses six magnets at different locations in the
processing line to removal ferrous metal (Karakesh, 1991). However, the cost
of redundancy in additional separation and screening equipment can become
prohibitive, depending on prices paid for the processed wood. Processors
select equipment on the basis of the types of waste wood they expect to
process, the required quality, the expected end use, and the price paid for
the end product. It is generally uneconomic for a processor to invest in high
removal efficiencies if, for example, they plan to process wood only for
landfill cover. Similarly, fuel specifications for a refuse-to-energy plant
that also burns processed wood are usually less stringent than specifications
for a wood-fired power plant (Gent, 1991}.
5.4.3.2 Time Spent at Cleaning Stations
A second factor affecting the removal of non-wood contaminants is the time
that a given volume of waste wood spends at key steps in the processing. This
is a function of the equipment design, overall processing capacity of the
facility, and desired production costs per unit of processed material. At
most cleaning stations, a long residence time improves the separation of
5-12
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ui
i
u>
"4
VISUAL LOAD INSPECTION
0
N
A
L
C
A
L
REJECT LOADS
TIPPING HALL
PEED CONVEYOR
VISUAL INSPECTION
MANUAL NONPROCES-
SIBL1 MATERIAL
REMOVAL
FERRO-MAGNET #1
METALS
DISC SCREEN
SIX INCH MINUS
PASSING SCREEN
ONE INCH
TROMMEL SCREEN
HAMMER MILL
•ONE INCH MINUS
ONE TO SIX INCH
MATERIAL RETAINED
FERRO-MAGNET #2
i f
METALS
OPTIONAL'
FLOTATION
TANK
WATER CLASSIFIER
RUBBLE AND GRIT
I
Z
TROMMEL OR
VIBRATING
VARIOUS
INTERMEDIATE SIZE
VARIOUS FINE SIZE
Figure 5-1. Generic wood waste processing facility
-------
non-wood material. For example, additional revolutions in a rotary trommel
screen produces a higher removal dirt and fines. Convers ely, high conveyor
speeds at manual picking stations may prevent adequate sorting of non-wood
material, that in turn affects the capabilities of other cleaning stations in
the processing line {Gent, 1991).
5.4.3.3 Waste Wood Composition
A third factor relates to the composition of waste wood material when it
arrives at a cleaning station. For example, material that is thinly and
evenly dispersed on a conveyor belt will achieve better metal removal
efficiencies at crossbelt or plate magnet stations than material that is thick
and lumpy (Karakesh, 1591}. Waste wood that is sticky or forms clumps due to
moisture ox a film of composted material will shed lass dirt and fines in a
trommel screen than wood that is dry and loose (Gross, 1991) »
5.4.3.4 Equipment Design Capacity and XSsm
The fourth factor relates to the manufactured design capacity of a specific
piece of processing equipment, compared to the amount and rate of waste wood
actually handled by the equipment.
Prior to the late 19801s, most processing facilities relied on
processing equipment developed originally for either the forest products or
mining industries (Groscurth, 1991). This has changed dramatically during the
last several years, due to the growth in recycling. For example, as of late
1991, more than 3 0 North American industries manufacture and sell shredding
and hogging machines for use in waste wood and demolition recycling !Recycling
Today. 1991).
In addition, there is a trend by manufacturers to increase the versatility of
their equipment to handle the varying compositions of different waste streams,
changing climatic conditions, different moisture contents, and different
end-use market requirements. Manufacturers are providing variable speed
motors, a wide variety of trommel screen sizes, adjustable hopper feeders, and
adjustable conveyor speeds (Ohanessian, 1992).
Most waste wood processing equipment in use today achieves from 60 to 95
percent removal efficiency of non-wood materials. However, the actual removal
efficiencies depend on the specific type of equipment and the way it is
installed, operated, maintained, and used. There may be certain types and
brands of equipment that can achieve close to 100 percent removal of specific
materials, such nails or staples. For example, many trommel screen
manufacturers indicate chat under the right moisture conditions and feed
rates, the removal of undersized material is better than 95 percent (Payne,
1991). The design and capabilities of specific equipment types are discussed
in more detail in Section 5.5,
5.4.4 Separating Wood from Non-Wood Substances
The initial processing and separation of non-wood materials at
wood-only and multi-waste processing facilities focuses on volume reduction
for handling purposes. This is generally followed by the removal of dirt,
rocks, and metal that can cause substantial wear and tear on sizing and
sorting equipment (especially for equipment designed only to handle wood}. At
some facilities, all waste wood is sent through the same sorting and
separation line regardless of how cl«an it is when it arrives. This may be
true, although facility owners charge lower tipping fees for presorted, clean
waste wood.
5-14
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Other facilities handle demolition wood and treated wood accepted at a
facility differently than clean, non-demolition wood. Frequently, demolition
and treated wood are either unloaded at separate locations at the site, or are
sorted on-site before entering the processing line. The demolition wood
and/or created wood is then processed in a separate line from the clean wood.
The separate line for demolition and/or treated wood may include an
industrial-scale C&D debris shredder, scalping screen for sorting large chunks
of brick and rock, or float tank to rinse the wood before grinding and
screening.
Following the sorting and cleaning steps, the demolition and/or treated wood
may be commingled with clean wood, for the rest of the processing line
depending on the requirements of the facilities' end use markets. Most
wood-fired facilities have specifications for processed wood used for fuel.
Fuel specifications may cause some processing facilities to keep a line for
clean wood entirely separate from the line for demolition and/or treated wood.
Separate processing lines are usually used by processors that have relatively
different product specifications with specific customers. Examples include
landscaping and fertilizer customers for whom small fractions of non-wood
material is unacceptable, or fuel customers for whom only a certain percentage
of non-combustible material {usually three percent or lower) is allowed as
part of their purchase agreement with the processor.
An example of an on-site sorting and processing stage for demolition wood is
provided by a multi-waste processing facility located in the study area that
starts by feeding mixed construction and demolition debris into a heavy duty
C&D shredder. Wood and debris then move up an inclined steel conveyor belt
and fall onto a downward sloping large-mesh shaker screen that allows heavy
material less than one-inch square to fall out. Six- to eighteen-inch wood
pieces and other debris drop from the shaker screen into a float tank. Wood
is floated off in one direction in the tank. Remaining pieces of heavy debris
such as rock, brick, metal, and concrete are removed in the opposite direction
by a drag chain located on the bottoir. of the tank. Wood from the float tank
then passes through a manual picking station, where residual paper, plastic,
or metal is removed. This preprocessing precedes the sizing and cleaning
process steps. Subsequent steps in the processing line include a tub grinder,
magnet, disk screen, and rotary trommel.
Facilities are configured differently, based on their individual design, waste
wood supply, and end-use .markets. Table 5-2 compares equipment used and
quantities produced at eight waste wood processing facilities in the study
area. The table provides a representative sample of the range of material
processed, and equipment used at processing facilities.
5,5 Waste Wood Processing Equipment
This section describes equipment used at facilities that process waste wood
for fuel and other products. The discussion includes both equipment used at
facilities that only accept presorted waste wood, and at facilities that
accept multiple types of waste, such as construction and demolition debris
containing wood and other waste. A wide range of equipment types and sizes
are currently available to wood processors in the U.S. and Canada. For
example, at least 26 companies in North America supply screening equipment
and at least 33 manufacturers supply grinding and chipping equipment
(Recycling Today, 1991). Many manufacturers produce more than one size and
model of equipment.
Wood processing equipment is evolving in response to fuel specifications and
new demands for other products recovered from the wood. The types of
equipment used by processors depend on each facility's unique circumstances
5-15
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Table 5-2. Representative waste wood processing facilities.
Major facility characteristics*
A
B
c
D
M
F
6
H
GENERAL
incoming tipping fee1"
Processing capacity, tpy
Aver ago noistura content of wood fu«l
$18-27
300,000
20-25%
$40
100,000
15-25%
$12-24
15,000
20-30%
$24-72
30,000
7-15*
$15
12,000
20%
$25-29
88,000
20-25%
$61-110
200,000
9-15%
$50-60
75,000
15-20%
INSPECTION
Visual inspection at tb* gate
Written standard;- for acceptable waste woocf
PtesD-jre treated or creosote wood not accepted
Receives "dedicated* loads ot waste wood
Material is weighed before unloading
X
x ,
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
PROCESSING LINE(S)
Pre-sorting/primary classification;
Front-end loaders or cranes
Manual picking station, before grinding
Rotary trommel classifier(s)
Rotary 01 "scalping" screen classifier
Float tank for metal/rock/dirt removal
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Sizing equipment:
ckT) multi-waste shredder or iiepactor
Tub grinder/hogger
Hammermill shredder
Rotary trommel screen is)
Oscillating deck or finger shaker screen(•)
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Major removal equipment used:
Ferrous metal separation before grinding
Ferrous metal separation after grinding
Electronic metal detection
Specialized rock/metal air classifier
X
X
X
X
X
X
X
X
X
X
X
X
X
Secondary classification *
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Table 5-2. Representative waste wood processing facilities (continued),
WOOD PRODUCTS PRODUCBD
Soil/fines (< * inch)
X
X
X
X
X
Mulch/compost <* - 1 inch)
X
X
Fual chips (1-4 Inches)
X
X
X
X
X
X
X
MAJOR MftRXEfS
Wood-fired power plants
X
X
X
X
X
X
MSW incinerator
X
Lands c ap i ng/nur amy material
X
X
X
X
X
Compost material
X
[Bulking material (or aludg*
J Landfill cover
X
X
[Flakeboard manufacturing
..
X
Notes:
a. Facilities are reported anonymously in this research.
b. Several facilities use a tiered pricing schedule based on the level of contaminants in the wood. For
example, at Facility A a $9 per ton surcharge is added for waste wood containing "observable quantities
of lock and dirt.* Facility D charges $4 per cubic yard for "clean* sorted waste wood, wood with any
metal attached starts at $6.50 per cubic yard, and wood containing significant amounts of dirt, rock,
metal or non-wood material may be charged .as much as $12 per cubic yard.
c. Several processors charge a higher fee, as much as double the normal amount, for excessively dirty
loads. Alternatively, processors will frequently charge a lower tipping fee to haulers who bring
"dedicated" loads of pre-sorted wood material. For example, in the case of Facility E, a hauler is
charged #4 per ton less for pre-sorted, dedicated waste wood than the normal fee of $29 per ton.
d. The rule for most waste wood processors is no more thatn 5% of a load can be contaminated with painted,
CCA-treated or creosote-treated wood.
-------
other materials) accepted at a facility are circulated to haulers and posted
at the processing facility. Appendix E. contains the written specifications
for waste wood received at two processors in the study area. Although
specifications vary among processors, these are believed to represent the
level of detail and overall approach used in the U.S. and Canada-
• A deposit is collected and held by a processing facility until after a
load of waste wood is dumped and checked. This deposit may be twice the
normal tipping fee {Kenedy, 1991) . If the load contains unacceptable
materials, the deposit is held to cover the cost of either disposing of
the material, or reloading it into the hauler's truck.
• A surcharge is added to the tipping fee If the load contains excessive
amounts of unacceptable material. The surcharge covers either the
additional handling and processing costs, or additional handling and
disposal costs if the material must be discarded.
• Lower tipping fees are charged for haulers who provide "dedicated loads"
of presorted, acceptable material (Toraasso, 1991). The lower tipping fee
is offset by lower processing costs for handling, sorting, and screening
the material.
5,5.2 Mast® Mood Sorting
Many processing facilities sort material on-site before processing it, to
separate clean wood such as pallets arid construction scrap from wood with a
high dirt content, non-wood material attached to the wood, or other commingled
waste. Sorting on-site is common at multi-waste facilities that accept and
process a wide range of materials. Sorting on-site may be done at wood-only
facilities, especially to separate clean from'treated wood.
Several factors affect the type of effort involved in sorting at processing
facilities. At some facilities, when wood is determined acceptable during
inspection at the gate, further on-site sorting is considered unnecessary.
The belief is that inspection at the gate and/or tipping fee incentives
successfully restrict unacceptable materials. At other facilities, on-site
sorting is constrained by the site layout and lack of sorting space. If there
is not sufficient room on-site for sorting, more emphasis is placed on
inspection at the gate. In addition, if a facility receives large numbers of
relatively small loads {i.e., pick-up trucks) then emphasis is placed on
inspection at the gate because the unloading area can quickly become
congested, and the time involved in unloading can be inconvenient for haulers.
On-site sorting is used at facilities that have separate processing lines for
different types of waste wood and for different end products recovered from
the material. This is especially true for processors that have large
landscaping mulch or fuel customers that require the end product to meet
certain specifications. In addition, the use of processing systems that
int roduce clean material at intermediate stages in the processing line often
require waste wood sorting ia the yard.
On-site sorting is usually accomplished in one of the following ways.
• Trucks are directed to unload at separate locations in the yard,
depending on which processing line will be used for the material. This
occurs at both wood-only and multi-waste facilities.
• Ail material is unloaded in the same area and a bobcat tractor or
front-end payloader sorts it into discrete piles, based on visual
characteristics of the wood and other debris. When wood and other
5-18
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materials are sorted in the yard, they are moved to the appropriate
processing lines primarily at multi-waste facilities,
• All material is unloaded in the same area at, or near, the beginning of
the processing line. As Material is loaded onto a conveyor at the
beginning of the line, it is sorted either mechanically or manually.
5,5.3 Primary Grinding Equipment
the size reduction of bulky waste wood, an essential step in
preparing wood for fuel, is primarily accomplished by grinding the material.
At many facilities, a tub grinder or C&D impactor is used early in the
processing line to grind the material and reduce its volume, because the
efficient performance of other processing equipment requires material that has
had its -volume reduced. Loose, fairly uniformly sized wood chips are easier
to sort, handle, and convey than bulky waste of widely varying sizes and
shapes.
Grinding also loosens non-wood material attached to waste wood, such as
plaster, paint, or nails. The loose material allows for more efficient
screening and removal at other stages. Secondary grinders, such as high-speed
hammermills, may be used later in the processing line for final size
classification, especially waste wood processed into fuel, since a consistent
and uniform particle size is significant in maintaining combustion
performance.
At on# facility, wood containing large amounts of dirt and rock travels
through a series of rotary trommel screens before being ground to remove the
dirt and rock. The oversize pieces are carried through the screens to a
manual picking station, before the initial grinding.
Three major types of grinding equipment are used at processing
facilities including hammermills designed specifically for waste wood., hoggers
and tub grinders designed specifically for waste wood, and construction and
demolition debris shredding machines designed to accept mixed, balky
construction and.demolition debris. Major features of these types of grinding
equipment are summarized below,
Hammermills;
• Used for primary size classification;
• Usually horizontal shaft, swing-hantner types;
• Usually 100 to 500 horsepower,*
• High torque, high speed?
• May be mobile or stationary;
• Produce particle sizes from 1 to 5 inches
• • Typically grind 10 to 50 tons/hour of wood; and
• Use different hammer configurations, depending on type of wood
and end product.
Hoggers and Tub Grinders:
• Used for primary size classification;
5-19
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• Consist of either gravity fed, horizontal rotor machines with
•punch and die" hammers, hourglass cutting knives, or
articulated hajrcmers;
• Typically 60 to 300 horsepower, depending on volume and demand;
• High torque, high speed;
• Produce particle sizes from 1 to 5 inches;
• May be equipped with metal detection equipment;
• " Process 10 to 50 tons/hour of wood; and
• Use different cutter configurations, depending on. the type of
wood and end product,
C&D Shredders and Impactors:
• Used for initial volume reduction of oversized construction,
demolition, and bulky waste;
• Typically 600 to 800 horsepower;
• Either high or low torque, depending on the type of waste;
• Wood requires further size classification and screening after
shredding;
• Produce wood sized from 6 to 18 inches;'and
• typically processes 100 to 500 tons/hour of material.
5.5.4 Float Tanks
Float tanks can be used to separate rock and metal from waste wood.
Currently, most facilities do not use float tanks, although several facility
operators interviewed are considering installing them. Key advantages are the
avoidance of additional screening equipment or manual picking, and the high
removal of dirt and sand. Newer float tank systems with pressurized jets can
wash off fine dirt residues and can prevent waterlogged wood from dragging
along the bottom of the tank (Payne, 1991;.
Key disadvantages of using float tanks are wastewater discharge concerns,
difficulty in operating in cold weather, waterlogged wood, and binding
material in underwater drag chains used to clean settled material out of the
tank. At least one processor heats water in the float tank. The operator
believes this helps the wood float and alleviates potential binding or
clogging !Vinagro, 1991). Some facility operators use chemical tlocculents
that cause fine material to clump, or they treat the water to lessen, the
frequency of replacement. Water replacement is necessary eventually, however,
since wood absorbs water while in the tank.
Float tanks are used in the middle of the processing line, usually after
initial grinding and screening. At one multi-waste facility, for example, the
float tank is located between a primary shredding machine and tub grinder.
The wood arrives at the tank in fairly bulky pieces, 6 to 18 inches long. At
another facility, the float tank is located after demolition wood passes
through two trommel screens, a handpicking station, and an air knife. The
5-20
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wood passes through the float tank and then through a hammerroill, magnets, and
disk-shaker screen.
The most unique float tank system observed in the study area consists of a
rectangular open pit or lagoon {approximately 20 by 40 feet}» rather than an
actual tank. At one end of the lagoon, a disk-shaker screen empties wood and
remaining debris into the water. At the opposite end, a conveyor lifts wood
out of the water and conveys it to a tub grinder. Two backhoe tractors with
front bucket loaders are situated on opposite sides of the lagoon. They use
the backhoe boom to scrape heavy debris out of the bottom of the lagoon. The
debris is then piled on the side of the lagoon. The material is removed to
other locations using the front bucket loader.
5.5.5 Manual Picking Stations
Manual picking stations are common at multi-waste facilities ana are used to a
lesser extent at wood-only facilities. Manual picking stations tend to have
one to five people per shift. Picking stations provide an important visual
check for material entering the processing line. In addition, the use of
picking stations helps prevent excessive equipment wear or breakage by sorting
materials that may bind moving parts on mechanical systems.
Larger picking stations of four to five people remove oversize pieces of rock,
brick, concrete, or stumps. These materials are usually "picked" from a
moving conveyor bed and tossed or sorted into bins or roll-off boxes located
directly behind, or beneath, the picking station. The picking station is
usually located near the front of the processing line, after initial screening
by a rotary trommel or disk scalper, and before primary grinding for size
classification.
Smaller picking stations of one to two people are usually located after
initial grinding, screening, and washing, but prior to final grinding and
screening. The smaller stations screen for small pieces of metal or plastic
still attached to the wood. In addition, a facility may have a one-person
station situated at the base of the final conveyor belt that leads to the fuel
storage pile. The purpose of this station is to remove small bits of paper or
plastic that may cling to the processed wood chips {Gross, 1991).
5.5.6 Mechanical Screening Equipment
Mechanical screening systems are widely used for sorting, cleaning, and sizing
waste wood. Major types of equipment include disk or scalping screens, rotary
trommel screens, oscillating or shaker screens, and air classifiers, Major
features of screening equipment are;
Disk Screens;
• Usually designed as a primary screen for use prior to, or
immediately following, initial grinding. The screens typically
sort material from one to six inches minus in size.
• Screens consist of either wire mesh screens, a series of metal
"scalping* disks arrayed across a series of spinning axles, or a
series of rotating metal "fingers."
• Screens are designed to sort material while also conveying
material through the processing line.
Rotary Trommel Screens:
5-21
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• Use steel or urethane cloth mesh screens ranging from 3/8-inch
to 2-inch mesh. Larger meshes are used for specialized waste
streams or screening bulky materials. Depending on the drum
size, waste wood composition, mesh size, and power rating,
rotary trommels can be used at multiple processing stages.
• Typically process from 15 to 75 tons per hour using 100 to ISO
horsepower motors; finished output is 100 to 150 cubic yards per
hour.
• Removal efficiency is highly dependent on the moisture content
and physical composition of the material.
• Typical drum sizes are 6 to 10 feet in diameter and 16 to 40
feet long,
• Newer models utilize variable speed motors for feeder hoppers,
conveyors, and trommel drums.
Air Classification and Air Knife Separators!
• There are two basic types. High velocity blowers push lighter
materials, such as wood and paper, across an opening where heavy
material, such as rock, metal, and glass, falls out. Vacuum
systems pull material out of the processing line.
• High velocity air streams are used for-the primary
classification of heavier material, such as rubble and other
debris, from lighter material, such as wood, paper, and plastic
{Killigas, 19911.
• Vacuum systems, commonly referred to as "air knifes," are used
for fine screening, such as pulling small bits of paper,
plastic, and other light debris out of the waste stream.
Oscillating and Shaker-Deck Screens;
• Horizontal or inclined deck screens are used primarily near the
end of the processing line (often referred to as the "finishing"
line) to separate residual wood particles and other small
particles, or "fines," from the finished fuel chips.
• Screens operate in a reciprocating or circular shaking motion.
The decks may be inclined 15 to 25 degrees.
• Decks range in size from 2 by 4 feet, to 7 by 20 feet. They are
powered by electric motors ranging from 10 to 30 horsepower.
• The screens can be stacked in double or triple decks to provide
more complete screening capabilities.
• The output capacity varies widely, based on the type and size of
deck, and the wood material.
5,5.7 Metal Removal
Initial metal separation is achieved through inspection and screening
procedures previously discussed, or manual picking stations that screen
oversized rock, metal, rubble, concrete, and other non-wood items. Picking
5-22
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stations may be accompanied by float tanks that settle nails and other small,
loose pieces of .metal undetected by manual sorting or visual inspection.
Magnets are commonly used to retrieve ferrous metal, such as nails, wire, or
staples. Three types of magnets are widely used, including rotary belt
magnets, bar and plate magnets, and magnetic head pulleys on conveying
systems,
Rotary belt magnets are positioned directly before and after grinding
equipment. They range in size from on# foot to several feet wide. With tub
grinders, magnets are typically located just after the grinding process. At
one facility, a manual picking, station for metal, plastic, and paper was
located between a C&D shredder and a tub grinder, with additional magnets
located following the tub grinder. At least two rotary belt magnets are found
in most large scale waste wood processing lines. The magnet picks up metal
fragments, and deposits then in a. bin located adjacent to the conveyor. A
second or third magnet, such as a stationary bar magnet, may be used towards
the end of the processing line.
Rotary magnets are usually suspended from eight- to twelve-inches above a
moving conveyor. Rotary magnets are self-cleaning and require minimal
maintenance. Bar magnets are suspended closer in order to pick up the
smallest residual fragments. Bar magnets must be cleaned periodically to
remain effective. Magnetic head pulleys are provided with many conveying
systems, A typical design used is on an inclined conveyor. When material
reaches the top of the conveyor, ferrous material "sticks* to the conveyor
belt as wood proceeds to the next processing stage. The metal is then carried
by the belt part way around the head pulley, and is dropped, into a bin
underneath the conveyor.
Metal detection and removal technology is changing. At least one facility in
the study area uses a special'metal detection system built into the hamraerroi 11
unit that detects pieces of ferrous and non-ferrous metal above a certain size
and electronically shuts the hanmermill off before the metal can damage the
cutters. Metal detection units operate by passing material between electronic
sensor coils. The sensors shutdown the conveyor or hopper, if metal is
detected (Beck, 1991). At another facility, waste wood passes through a
series of four rock and metal separation stations using air classifiers. At
each station, lighter wood is blown past the heavier metal and other debris
with high-velocity air nozzles I Phillips, 19911 , Heavy materials fall out at
each station, successively cleaning the wood to a higher degree. In this
process, the redundancy results in thorough metal removal,
5.5,8 Fuel Storage Systems
Three fuel storage systems are used at waste wood processing facilities: open,
uncovered fuel piles; partially covered fuel piles, such as pole barns that
contain a roof ana open sides; and enclosed storage bins or hoppers. Major
factors affecting fuel storage systems are summarized below.
• Large processing yards located in dry climates such as
California, typically stare fuel outside in uncovered conical,
triangular piles or "tablet op" piles. As part of fire safety
precautions, outdoor facilities are usually required to maintain
fire lanes and follow minimum height and spacing standards
between fuel piles. Common height standards are 20 to 50' feet.
Common standards for spacing between piles are 20 feet.
• Where storage space is minimal or where air pollution
regulations require it, some facilities store fuel in enclosed
5-23
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bins. The bins provide additional dust control and allow the
facility to meter chips that are sold fairly accurately.
• Typically, fuel is loaded into ISO cubic yard tractor-trailer
vans using front bucket loaders. Depending on moisture content,
the vans carry 24 to 3C tons of fuel. Facilities with overhead
bins can mechanically drop fuel chips into the vans, while
simultaneously weighing the truck.
• Facilities usually follow tor are required to follow) a "first
in-first out" policy for fuel deliveries to avoid excessive
biodegradation of the fuel. In some cases, however, fuel
processed from urban waste wood is too dry for some combustion
systems; it is purposely allowed to slightly decompose to raise
the moisture content (Remington, 1991} .
5.5,9 Dust Control Systems
The primary factors affecting the use of dust control systems at waste wood
processing facilities are whether the facility is located outdoors, and
whether the climate is commonly dry and windy.
Outdoor processing facilities in the western U.S. may be required to provide
several levels of dust control. This can include permit conditions that
require watering storage piles and certain locations at the facility during
specific intervals, or while certain equipment is operating. An example is
the requirement to continuously wet the staging area where a grapple crane
loads waste material onto a conveyor {Gross, 1991}.
Other facilities (located either indoors or outdoors) must provide ventilation
and fabric fil ter particulate collection systems* For example, an outdoor
waste wood processing facility recently permitted in California is required to
use three fabric collectors, that have 5,000, 2,000 and 3,000 square feet of
filter area. The collectors feed a dozen hood ventilation stations located in
the processing line {Kern County Air Pollution Control District, 1991).
5.6 Summary of Processing Facilities in the Study Area
This section describes waste wood processors observed and interviewed for this
research. Table 5-3 and Table 5-4, respectively, list major stationary waste
wood processing facilities in and outside of the study area. It is important
to note that facilities listed in the table are not necessarily only wood fuel
processors. Most facilities process wood for multiple markets. Due to the
similarity of certain types of equipment used among processors, many hav« the
capability to process wood for fuel in the future, if a market were available.
5.7 Case Studies of Processing Facilities
Case studies of two waste wood processing facilities are presented below. The
first describes an indoor facility that only accepts and processes wood. The
second describes an indoor/outdoor facility that accepts wood and mixed
construction and demolition debris. The facilities are described anonymously,
due to agreements made concerning their participation.
5.7.1 Wood-Only Processing Facility
This processor has the capacity to process 350 tons per day of wood, or
100,000 tons per year. The facility averages an output of about 200 tons per
day. The wood waste processing equipment is located on a two-acre site.
Although the wood processing facility is on a self-contained site, it is part
5-24
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Table 5-3. Waste wood processing facilities in the study area*b
California
Connecticut
Mew York
Worth Carolina
Virginia
Washington
Wisconsin
Fiber Fuel
PLC
Automated Waste
BQB Wood
Cumberland
Wood Recycling,
Redmond
Northern States
Products,
Organics,
Disposal,
Recycling,
County Solid
Inc., Lorcon
Demolition,
Power, LaCrosse
Cose* Sesa
Inc., sun
Valley
Danbury
Brooklyn
Waste Cists ice,
Fayetteville
Interstate
Redmond
and Ashland
Artes ia
Manafort
Hubbard Sand &
Pallet, Roanoke
Pacific Topsoil,
Brunatta Box
Sawdust
Zanker
Brothers,
Gravel, Bayshore
City of Winston-
Seattle
Factory, Rice
Prodvicts,
Materials
Plainville
Sal an
Cooper Wood
Lake
Gardena
Recovery,
Industrial
Products, Rocky
Murray Pacific,
San Jose
Wast#
Recycling systems.
Wrico
Mount
Tacoma
forest Fuel
Keliog
Management,
Croton-on-Hudson
Construction,
Corp. „ Iron. River
Supply. Inc.,
Sequoia
Norwalk
Highpoint
Street Wood
Olympic Fiber,
Carson
Forest
Karta Recycling,
Products,
Graya Harbor
Anderson Wood
Products,
Recycled Fibers
peekski11
City of
Barhamsville
Fuels, Spancar
Recycled Wood
Dimiba
of CT,
Highpoint
Simpson Timber
Products,
Manchester
Red Hook
Pallet Sarvica,
Co., shelton
Rouse Wood Chips,
Monterey Park
liignetics,
Recycling,
City of
Lynchburg
Shawano
aiid Berkeley
inc.,
Pasadena
stapleton
Brooklyn
Charlotta
Paxport lac.,
Resource
United Biofuels
Tacoma
Nagel Lumbar Co.,
city of
Recycling,
Star Recycling,
Inc., Richmond
Land. O' Lakes
BaJt«rsfi«ld
Angelus
Sawdust,
Bridgeport
Woodside
Allen chipping.
Bdxum Co»,
Tacoaut
Knercon, Hartford
Waste Fiber
Los toggles
McCauley
Universal
Emporia
Recovery,
Enterprises,
Demo lit. ion
Girard Pallet,
Brandner Timbar
Hayvard and
Regenesis
Hartford
Recycling, Putnam
Hi!Icq Inc.,
Puyallup
Corp,, Westboro
Auburn
Recycling,
Fairfax
Wilmington
Supreme Forest
Town of Beacon
Harbor chipping.
Woodchip, Corp.,
United
Products,
S.W. Rogers Co.,
Tacona
Merrill
Pacific
Central LA
Bristol
Gainesville
Corp., Sun
Recycling &
Dally
valley and
Transfer,
William Hazel
Landclearing,
Santa Fa
Los Angeles
inc.. Chantilly
Tacoma
springs
Chino
Rabancc Waste
Marine
Valley
Services,
Resource
Sawdust,
Seattle
Recovery, San
Ontario
Rafael
last#!*
Community
Recycling,
Recycling &
El Montm
Recovery, Sun
Valley
Milestone
Energy
Hayden
Corp,,
Brother®, Sun
Pacoima
Valley
Valley Roil
Delano
Off,
Eicasass
Sunland
Energy,
Delano
Notas:
a, Includes cnly major stationary nvuXti-waste and wood-only recycling and processing facilities. It cloes not inelud* processing
equipment such as noMla tubgrindsrs. Etump grinders, chijjpers. or mobile waste processing facilities,
b. New Brunswick and Vermont have no major stationary waste wood processing facilities currently operating
-------
Table 5-4. Examples of waste wood processing facilities outside the study
area.
r
United States
—j
Canada J
Rhode Island
New Jersey
Massachusetts
Ontario
New England
Advanced
Jet-A-Way, Inc.,
Harkow
Ecological
Enterprises,
Boston
Aggregates &
Development,
Newark
Recycling,
Johnston
Mr. Chips, last
Partyka Resource
Management,
Toronto
Truk-Away, Warwick
Brunswick
Chicopee
Canadian Eagle
Recyclers,
Florida
Tony Canale, Egg
Regional Waste
Brampton
Wood Resources
Harbor Township
Services,
Recovery, Inc.,
Peabody
Monto
Gainesville
Winzinger
J ndus t r jl e s,
Recycling Systems,
.Recycled Wood
Toronto
Delaware
Hainesport
Products, Woburn
CfitJ Associates, Hew
Wood Waste
Castle
New Hampshire
C.J. Mabardy,
Solutions,
Environmental
Cambridge
Toronto
Delaware Recyclable
Resource Retur
N
Products, New
Castle
Corp., Portsmouth
Eco-Wood
Granite State
Products,
Toronto
Maine
Natural Products,
Fuel Technologies
Salem
Wood
Inc., Lewiston
M-R Land
Excavation,
Merriroac
Conversion
Inc. , Brampton
of a larger, integrated recycling operation that also sorts and processes
metal, glass, paper, and other items.
As of late 1991, tipping fees at the facility are $6 per yard, or
approximately $30 per ton. A11 types of "urban" and demolition wood are
accepted, except loads containing visible amounts of creosote- or
penta-treated wood.
The unloading area and processing line are located in an enclosed building,
the facility receives most wood through a regional construction, yard waste,
and an urban wood recycling program. Wood is brought to the facility by
private haulers, contractors, landscapers, and homeowners. Cars, trucks, and
trailers are weighed and visually inspected at a booth outside the building,
before proceeding to concrete unloading docks inside the building.
The unloading dock is organized into 6 to 8 bays where vehicles back up to a
low concrete berm. Wood waste is either dumped or thrown off a one-foot drop
onto a concrete floor. A front-end loader pushes wood that is visibly clean
onto a three-foot wide belt conveyor that leads directly to a hanxnermill.
Construction and demolition wood, or wood with non-wood materials attached to
it is pushed onto a conveyor that leads to a three-person picking station.
Following separation at the picking station, wood is returned to the
hammermi11 conveyor. The facility operator plans to install two rotary
trommel screens to further separate dirt and fines, before wood is sent from
the picking station to the hammer-mill.
5-26
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The 400' horsepower hammermill unit includes an electronic metal detection
device that detects ferrous and non-ferrous metals before wood enters the
hammermill. The detection system automatically shuts the hammermi11 off, if
metal above a certain weight or volume is detected in order. This is done to
protect the hammers. Very small metal fragments which pass through the
hammermill are retrieved by a rotary magnet positioned after 'the wood chips
and fines emerge from the harranermill.
Wood then travels to a horizontal vibrating disk screen that sorts the wood
for either fuel chips or wood fines. Fines consist of 1/4- to 3/4-inch minus
material and are conveyed to a roll-off box for shipment to a soil and
fertilizer manufacturer. Fuel chips between 3/4- to 3-inches? are conveyed to
two overhead hoppers that hold approximately 180 yards apiece.
Tractor-trailers enter the back of the building and drive onto an electronic
scale directly underneath the hoppers. The chips are then loaded into the
trucks for delivery.
A unique feature of this facility is the system used to control dust and odor.
This was the primary reason for constructing an indoor facility since the
facility is located adjacent to a busy commercial area. In addition, along
the processing line, there are four hood and vacuum systems that feed dust and
particulates to a cyclone located near the hammermi11. From the cyclone,
remaining dust and pollutants are pumped outside the building, directly into a
40-foot baghouae filter system located next to the main building. At the
unloading bays, water is sprayed to control dust approximately every 30
minutes.
Wood fuel with a moisture content of 10-20 percent is purchased by three power
plants, The hauling distance is typically 100 to 200 miles one way. The
facility operator reports that the power plants he ships to are very sensitive
to moisture and dirt content. For example, wood fuel in excess of 20 percent
moisture is rejected. Installation of trommel screens for additional dirt
removal will, according to the plant operator, further satisfy his fuel
customers.
5.7.2 Multi-Waste Processing Facility
This facility has the capacity to process up to 1,500 tons per day of mixed
construction and demolition debris. This includes the capacity to process up
to 300 tons per day, or approximately 90,000 tons per year, of wood. The
facility receives a steady supply of wood, due to recent landfill bans on wood
disposal at a major landfill located nearby. The site is situated on .11
acres. In addition to wood, mixed C&D waste, newspaper, glass, concrete,
gypsum, and crushed rock are accepted and processed. Machinery is housed in
two facilities that feature a mix of indoor and outdoor processing stations.
Wood is delivered to the facility by public and private haulers, construction
and demolition contractors, landscapers, and homeowners. In late 1991,
tipping fees for presorted wood were $25/ton and for mixed C&D waste were
$29/ton. Trucks are weighed and inspected, from a catwalk bridge located ten
feet above grade which allows visual inspection from the second floor office.
The facility posts a list of materials accepted for processing at the gate,
and also relies on personal communication and contracts with regular haulers.
According to the processors* specifications, all types of construction,
demolition, and other waste wood is accepted, excluding pressure-treated and
creosote-treated wood.
Wood enters the processing line at two locations. Mixed demolition,
construction, and treated wood start on one line, referred to as the "demo
5-27
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line." Clean wood, such as pallets, lumber, spools, and yard waste start at
another line, referred to as the "finishing line."
After wood is processed at the demo line, it is brought to the
finishing line to be processed along with the clean wood. Wood is sold as
landfill cover and as fuel. The fuel has an average moisture content of 20 to
30 percent and is usually handled by a regional wood fuel broker.
The Demo Line; The demo line starts with a grapple excavator that feeds wood
and rubble into a hopper. From the hopper, wood is conveyed directly into
two, three-foot diameter rotary trommel screens that are aligned end to end.
The first trommel screens wood for fine dirt and loam using a 1/4-inch screen.
Wood and debris then pass under a rotary magnet, before being conveyed to a
second trommel. The second trontnel uses a 3/4-inch mesh screen for separating
stone, concrete, and other aggregate material.
Prom the second trommel, wood is conveyed into a building where it passes by a
4-person picking station roughly thirty feet long. Large rocks, stumps,
pieces of litter, chunks of concrete, aluminum, and shingles are removed at
the picking station and thrown into separate roll-off boxes. Not all material
that could be removed at the picking station is actually removed, due to the
high speed of the conveyor. At the end of the picking station, wood and debris
drop into a float tank. As the wood and material fall, an air knife pulls
residual bits of paper and plastic into a chute and litter bin located under
the end of the conveyor before the material falls into the float tank.
The float tank is heated by a small wood burner. According to the plant
operator, the warm water causes the wood to float better and allows the tank
to be used in cold weather. Every 15 minutes, a drag chain pulls rock, brick,
and other 'material off the bottom of the tank. This material is conveyed
outside to a roll-off box. Operation of the tank requires one full-time
operator, the operator catches heavy material that binds the drag chain, and
ensures that no materials other than rock, brick, or concrete are sent to the
roll-off box.
From the tank, wood is floated onto another drag chain and conveyor system
where it passes by a one-person picking station. This person sorts any
non-wood material still attached to the wood, before it is emptied into a
roll -off box outside the building. This "cleaned," slightly-wet, demolition
waste wood is then trucked to another location to enter the finishing line.
The Finishing Line: The finishing line begins inside a separate building,
where a small bobcat pushes wood onto an inclined steel conveyor belt. The
belt conveys the wood to a separating hopper. At the hopper, pieces of wood
less than three inches are screened and conveyed directly to a shaker screen.
Pieces larger than three inches are sent to a hogger that: grinds wood to a
one- to four-inch size. From the hogger, wood passes under a rotary magnet
and is dropped onto an oscillating horizontal shaker screen. The screen sorts
fuel chips and wood fines of 1/2-inch minus. The fines are conveyed outside
the building to a roll-off box. After fuel chips leave the shaker screen,
they pass under another rotary magnet before being conveyed to an outdoor fuel
pile.
5.8 The Effect of Tipping Fees and Disposal Costs on Mast# Wood for Fuel
Factors that influence the determination of tipping fees and how tipping fees
affect the availability of waste wood for fuel are discussed. Also discussed
are issues related to disposal costs faced by major generators of waste wood.
These sections provide insight into the major economic factors that affect the
disposal of waste wood and its availability for fuel.
5-28
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5.8.1
Tipping F*« Factors
Tipping fees are an important aspect of the economic infrastructure that
affects waste wood fuel availability and cost. Tipping fees vary by region
based on demographic, geographic, and economic characteristics. Highly-
populated urban regions, for example, typically face higher disposal costs
than rural areas. This is due to the relative lack of landfill space,
trucking and hauling costs, and the cost of siting and building new solid
waste management facilities. The metropolitan area of New York City, for
example, ships a portion of its municipal solid waste as far away as Ohio at
costs of over $150 per ton. Differing regulatory requirements between states
also affect the establishment of tipping fees. Many states, such as Vermont,
have added surcharge taxes to tipping fees to fund recycling programs, site
assessment studies, or to ensure chat money is available for landfill
remediation and closure.
Tipping fees also vary by the type of solid waste management facility.
Low-risk, relatively inert wastes are usually less expensive to dispose of
than waste streams containing higher potentially hazardous materials such as
medical wastes. Construction and demolition debris (C/D) landfills or "inert"
debris landfills, for example, normally charge less for disposal than MSW
landfills. Hazardous waste landfills usually charge more than MSW landfills.
Tipping fees correspond to both the demand for disposal capacity and the costs
associated with permitting,'siting, operating, and maintaining a facility. In
many regions, however, tipping fee schedules do not follow an obvious pattern.
In some states tipping fees at MSW landfills exceed tipping fees at waste-to-
energy plants while in other areas the opposite is true. This results from
the interaction of several factors including but not limited to:
• The unique size, type, and operating characteristics of a
particular disposal facility
• Differing contractual arrangements to dispose of waste with
private and public entities;
• Differing regulatory policies, standards, and required, control
technologies among states/ provinces;
• Differing facility requirements concerning the types and amounts
of wastes accepted for disposal,- and
• The level of competition among similar or alternative disposal
facilities.
Table 5-5 compares tipping fees in the study area among four general types of
solid waste management facilities that may accept waste wood for disposal.
These include MSW landfills, waste wood processing facilities, C/D landfills,
and waste to energy facilities. As the table shows, tipping fees at C/D
landfills and waste wood processors tend to be lower than tipping fees at
either MSW landfills or waste to energy facilities. In addition, fees at
waste wood processing facilities are slightly lower than C/D landfills while
fees at MSW landfills are slightly lower than fees at waste-to-energy
facilities.
With respect to waste wood processed for fuel, other cost issues also affect
the determination of tipping fees. These include the cost of processing and
hauling wood fuel, prices paid for fuel by combustion facilities, and
potential competition for wood waste among other end-use markets. Processing
5-29
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and hauling costs vary, depending on the type of wood, the design and
operation of the processing facility, transportation distances, and a variety
Table 5-5, Tipping fees in the study area, $US{1991)/ton*-fc.
State/Province
MSW landfills
Waste wood
processors0
C/D Landfills
Waste to
energy
California
10-50
10-30
la
20-30
Connecticut
60-100
50-100
50-70
60-85
Mew Brunswick,
CAN
25-35
NA
0-35
HA
New York
40-150
30-75
30-75
15-90
Horth Carolina
10-25
0-10
40-60
45-50
Vermont
20-70
NA
4-70
NA
Virginia
I Washington
|Wisconsin
20-60
30-45
10-20
10-20
20-50
30-40
je10-50i^
35
60-95
Notes:
HA « not applicable
a. Based in part on data from Biocycle, April 1991.
b. Based in part on interviews with state solid waste officials and facility
operators.
c. Depends on the types of wood to be disposed of, the level of
contamination, the extent to which wood is commingled with other wastes,
and the costs of disposal at other solid waste facilities,
of other factors. An important consideration for processors are the hauling
and processing costs not recovered by the price paid for fuel, The cost not
recovered is compared to the tipping fee otherwise charged for disposal. If
the cost not recovered is less than the tipping fee, then it is more
cost-effective to process and haul the wood for fuel than it is to pay for
disposal.
As previously noted in Sections 5-2 and 5,5, the level of contamination and
presorting cf waste wood prior to disposal may affect the tipping fee
assessed. In addition, processors must compare fuel prices to prices paid for
end uses other than fuel. If the fuel price is less than the price paid when
selling wood for other uses, then it may be more profitable to sell wood for
non-fuel uses. Cumulatively, these issues have a strong role in the
determination of tipping fees at waste wood processing facilities that operate
as disposal sites for waste wood and other materials. In general, a processor
that faces strong markets for fuel and other processed wood products is less
reliant on revenues from tipping fees than a processor who faces weak end-use
markets for processed waste wood. In other cases, however, the avoided cost
of iandfilling waste wood is sufficiently high to offset; processing and
transportation costs. In this situation a processing facility is less reliant
on prices paid by end users since the tipping fee charged at the gate
compensates for operating the facility.
5-30
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In most parts of the Northeast, Southeast, and New Brunswick, there is
generally a much larger supply of wood fuel than there is demand. The western
states of California and Washington, however, are more constrained in the
availability of harvested waste wood due to changes in forest practices. As a
result, the demand and prices paid for processed urban wood are higher than in
other regions of the study area. This is particularly true in California,
Based on information provided by brokers and suppliers in the Northeast,
however, prices paid for both harvested and non-harvested wood chips for fuel
have not increased substantially during the last five years. In fact, some
prices have decreased, particularly when inflation is taken into account. In
this situation, processors depend on the avoided costs of landfilling (high
tipping fees) to make up for the costs of processing and hauling fuel.
It is expected that waste wood processing facilities will be able to secure
supplies of wood only if their tipping fees are competitive with the cost of
other disposal options. This involves comparing tipping fees to be charged by
waste wood processors with fees charged by other disposal facilities. It also
involves comparing existing or proposed solid waste management regulations
which can have a direct impact on tipping fees. Significant penalties on the
disposal of certain types of waste wood used at many landfills affects the
rate of waste wood separation and diversion from municipal and commercial
waste streams. In addition, the increasing use of landfill bans on waste wood
disposal, such as in the province of Ontario, replaces the monetary incentives
created by tipping fees. Landfill bans can be expected to strengthen the role
of tipping fees at facilities that provide alternative disposal options, such
as waste wood processing facilities.
It is important to emphasize that the factors that affect tipping fees are
interdependent, changing, and localized among regions. As shown in Table 5-2
tipping fees at waste wood processing facilities vary by almost S100 from a
low of $12 per ton to a high of $110 per ton, this discrepancy results from
direct price differences such as high disposal costs in certain areas, varying
processing and hauling costs, and varying prices paid by end users. Indirect,
non-monetary issues also play a role. These include expectations about the
permitting of other disposal facilities, the development of reuse or recycling
markets for certain materials, or the perceived impacts of new solid waste
regulations,
5,8.2 Disposal Cost Factors
There are many types of residential, commercial, and industrial activities
that generate waste wood. The disposal costs for wood vary based on the type
and scale of activity, the types of waste wood generated, and solid waste
management policies and regulations in specific regions. This discussion
focuses on urban waste wood since disposal costs are typically a larger
concern for waste wood generated as a result of manufacturing or construction
than from harvesting or forest management activities.
Harvested waste wood from landclearing, landscaping, or primary mill residue,
however, may face similar disposal cost concerns due to specific solid waste
regulations and the type of waste generated. Disposal costs for harvested
wood and primary mill residue, however, typically range fro® no-cost (left
on-site or given away) to costs associated with hauling and disposal at either
a C/D landfill, inert landfill, compost facility, MSW landfill, or waste to
energy facility. Transportation costs are a primary disposal cost faced by
generators of harvested waste wood in urban or suburban areas where material
is often required to be removed from the site.
The majority of urban waste wood generation is related to various types of
construction activity that occurs among all economic sectors, and mill residue
generated from secondary wood products manufacturing. Treated mill residue,
5-31
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for example, may have to be managed and disposed, of as a solid waste if it is
not reused or burned on-site. Most wood products industries, however, are able
"to reuse, give away, or sell their mill residues for fuel, animal bedding,
soil amendments or other uses.
Waste wood from construction activities may be generated by new construction,
renovation, or demolition activities (GTHA, 1991). The largest user of new
wood products among these categories is residential construction. This does
not necessarily mean that new home building generates the most waste wood
however". Renovation and demolition projects may generate more waste wood on a
square footage basis than new home construction. A higher percentage of total
project costs are usually allocated to waste disposal for renovation jobs
rather than for new construction. According to research conducted by the
Greater Toronto Homebuilders Association (GTHA/, up to 8 percent of the total
job costs of renovation may be budgeted for waste disposal.
According to the same study, waste disposal costs for new homes contribute 4
percent to overall job costs. The GTHA estimated that a typical 2,000 square
foot, two-story home produced as much as 2 1/2 tons of waste per house of
which 40 percent {or one ton) is estimated to be waste wood. By comparison,
another large commercial and residential contractor in the southwest region of
the U.S estimates that 12 cubic yards (slightly over two tons} of waste is
created for homes from 1600 to 1800 square feet (Rush, 1991.) These figures,
however, are higher than "cleanup" estimates for new home construction given
by the National Horaebuilder'a Association (NHA). According to a 1990 national
study of new home construction costs by metropolitan areas, the MA estimated
that cleanup costs ranged from no more than §..4 percent of total costs in the
east and southeast and up to 1.5 percent of total costs in the west and
northwest area of the U.S. (Marten*on, 1992}.
Unlike the disposal costs associated with renovation and new construction,
demolition activities are by nature a "disposal cost." In addition, other
types of disposal costs such as hauling may be added to the coat of
demolition. Disposal costs from demolition activities are incurred for a
variety of reasons including preparation for new construction, removal of
health and fire hazards, or creation of open space. Demolition projects are
usually not a component of any particular commercial activity. Thus reliable
estimates about their impact on total project costs can be made only on a
case-by-case basis.
Similar to off-site disposal of harvested waste wood, transportation costs can
play a major role in the overall costs of disposing of urban waste wood.
Hauling costs are affected by how the waste is transported arid whether the
waste is processed prior to shipment. Large demolition projects, for example,
may use a mobile shredding machine to reduce the volume of material in order
to maximize hauling capacity and improve handling ability. Wood and other
wastes that are shredded prior to shipment are typically hauled at costs of $2
to $5 per loaded mile. Hauling costs for bulky wastes vary. They are often
absorbed as part of a flat fee offered by private hauling companies to dispose
of a certain volume of material, such as a 30 to 40 cubic yard roll-off
container. Alternatively, fees may be charged on the basis of variable
hauling costs and fixed disposal costs for a specified volume at a disposal
facility . An example is the use of flat fees for various truck sizes such as
$30 for a pickup truck at a Virginia C/D landfill. In addition to this fee
the hauler adds the variable costs of trucking.
5.9 Bibliography - Chapter 5
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Auburn, CA. Personal Communication. July 11, 1991,
5-32
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Fitzgerald, Bruce. Kenetech Energy Systems Inc. Meriden, CT. Personal
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Harrington, IL.
Gent, Floyd. P.E. Vice President Operations. KTI Energy Inc. Saco, ME.
Personal Communication. July 10, 1991.
Gitlin, Lisa. "Integrating Wood into the Recycling Loop". Recycling Today.
Cleveland, OH. June 1991.
Groscurth, John. Vice President. Triple/5 Dynamics. Dallas, TX. Personal
Communication. January 31, 1992.
Gross, Michael. Site Engineer. Zanker Material Recovery Systems. San Jose,
CA. Personal Communication. July 18, 1991.
Hawker, David. President. HAZEMAG USA Inc. Uniontown, PA. Personal
Communication. August 28, 1931.
Haybuster Manufacturing, Inc. Product Information Sheet on IG Tub Grinders.
Jamestown, ND.
5-33
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HAZEMAG USA Inc. Product information Sheet on Crushers, Uniontown, PA.
Hendricks, Lyn. Bonterra Systems. Richmond, VA. Personal Communication.
January 10, 1992.
Hi-Torque Shredder Co. Product Information Sheet on Hi-Torque Shredders.
Berkeley, NJ.
Jorgensen Conveyors, Inc. Product Information Sheet on Pitch Conveyors.
Mequon, MI,
Joseph, William C. Environmental Compliance Director. Wheeiabrator Shasta
Energy Company. Anderson, CA. Personal Communication. July 17, 1991.
Karakash, John. Fuel Procurement Manager. Viking Energy. Northumberland, PA.
Personal Communication. December 3, 1991.
Kenedy, Marc. Facility Manager. Hubbard Sand & Gravel. Bayshore, NY. Personal
Communication. June 11, 1991.
Kern County Air Pollution Control District. Authority to Construct. Fuel
Receiving Operation. Delano Biomass Energy Company Inc. March 22, 1991.
Killigas, Dewitt. Sales Engineer, Vibra-Con Associates. Hawthorne, NJ.
Personal Communication. December 9 and 16, 1991.
LD Industries Inc. Product Information Sheet on Material Handling Systems.
Myerstown, PA.
MAC Corporation. Product Information on Saturn Shredders. Grand Prairie, TX.
Misner, Michael. "Cutting Into Wood Waste Markets". Waste Aoe. Washington,
DC. August 1991.
Mittieman, Marc. Vice President Marketing, Research & Development. Canadian
Eagle Recyclers. Brampton, Ontario. Personal Communication. October 3, 1991.
Montgomery Industries International. Product Information Sheet on Montgomery
Hoggers. Jacksonville, FL.
Moore, Gene. Recycling Division, New York City Department of Sanitation. New
York City, NY. Personal Consminication. January 7, 1992.
Naef, Mark A. C&D Disposal In Onondaga County. C&D Waste Processors Meeting.
Northeast Industrial Waste Exchange, Inc. Syracuse, NY. March 1991.
Norkot Manufacturing Company. Product Information Sheet on Maxigrind 9100.
Bottineau, ND.
Norman, Orville. Solid Waste Engineer. Ulster County, NY. Personal
Communication. November 6, 1991.
Ohanessian, Mardi. Director of Marketing. American Recycling Equipment
Corporation. Parlin, NJ. Personal Communication. January 31, 1992.
Payne, Graham. Recovery Systems Technology Inc. Bothell, WA. Personal
Communication December 9, 1991.
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Philips, Gary. Facility Manager, Waste Fibre Recovery. Hayward, CA, Personal
Communication. June 18, 1991,
Progressive Architect/Engineers/Planners, Inc. Handbook for Conversion to
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WI. June 1986.
Pugh, Charlie. Royer Industries Inc. Kingston, PA. Personal Communication.
February 3, .1992.
Recovery Systems Technology, Inc. Product Information Sheet on Wood Waste
Recovery System. Frederick, MD.
Recycling Systems. Inc. Product Information Sheet on RSI Industrial Tub
Grinder. Winn, MI.
Remington, Fred. Manager Southwest Operations. Recycled Wood Products.
Berkeley, CA. Personal Communication. June 25, 1991.
Royer Industries, Inc. Product Information Sheet on Trommel Screen.
Kingston, PA.
Tomasso, Cathy. New England Ecological Development. Johnston, II. Personal
Communication. November 15, 1991.
Valtierra, Rubin. Site Manager, Marin Resource Recovery. San Rafael, CA.
Personal Communication, July 12, 1991.
Vinagro, Louis. President, New England Ecological Development. Johnston, RI.
Personal Communication. July 10, 1991.
Yvars, John. Recycling Coordinator. Westchester County, MY. Personal
Communication. November 6, 1991.
Winzinger, Heidi. Winzinger Recycling Systems. Hainesport, NJ. Personal
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Wolford, Leon. C & J Associates. New Castle, DE. Reference supplied by John
Karakash of Viking Energy. December 20, 1991* letter.
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6.0 WASTE WOOD COMBUSTION FACILITIES
6.1 Introduction
This chapter describes combustion facilities that burn waste wood for fuel.
Emphasis is placed on facilities that burn wood that is separated from the
waste stream and processed into fuel. The processed wood is derived from a
variety of municipal, commercial, industrial, agricultural, construction, and
demolition waste streams and is commonly referred to as "urban," "recycled,"
"treated," and/or "demolition" wood. In this report, the wood is referred to
as "waste wood" when it is in -its preprocessed form, and as "processed wood"
when it has been processed and prepared for fuel. Most facilities that use
processed wood for fuel also use harvested wood that is a byproduct of site
conversion, commercial logging, and forest management activities. In
addition, combustion facilities located in areas with wood products industries
frequently use mill residue for fuel. Similarly, combustion facilities
located in areas with large amounts of agriculture frequently use agricultural
residue for fuel.
This chapter also discusses key issues concerning fuel specifications and
procurement, fuel delivery and feeding equipment, furnace and boiler designs,
and pollution control equipment for combustion facilities that use processed
wood for all, or a portion, of their feedstock. The discussion applies to
power plants that burn processed wood exclusively for electrical generation,
and industrial facilities that burn processed wood to produce thermal and/or
electrical energy.
Section 6,2 provides an overview of major factors affecting the combustion of
processed wood for energy. The discussion is based on interviews with
regulatory officials, power plant operators and developers, site visits to
combustion facilities, and review of published material on the design and
performance ci combustion systems.
Section 6.3 details wood fuel procurement specifications and techniques used
by facilities that burn processed wood. As emissions and ash disposal
standards are developed for facilities that burn processed wood, more
attention is being paid to fuel content and quality. This in turn is causing
the development and use of fuel specifications at combustion facilities.
Section €.4 describes fuel delivery, storage, and equipment used at facilities
in the study area that burn, or would like to burn, processed wood. Although
a wide variety of equipment is in use, emphasis is placed on equipment used to
deliver, store, and feed non-harvested wood that was separated from the waste
stream and processed into fuel.
Section 6.5 describes combustion equipment used at facilities that burn, or
would like to burn, at least some processed wood as part of their feedstock.
Section 6.6 provides a summary of combustion facilities researched for this
study. Three tables are presented that compare equipment used by the
facilities. Each table includes information on facilities in a different size
range, based on boiler capacity. Information is included on the type of
facility, rated furnace or boiler capacity, type and amount of processed wood
and other wood fuel consumed, and combustion equipment used.
Section 6.7 includes case studies of two wood-fired combustion facilities
located in the study area. One facility uses a bubbling fluidized bed
combustion system. The other uses a grate-burning, spreader-stoker system.
6-1
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Both facilities are independent power plants that burn substantial amounts of
processed wood,
6.1.1 Key Issues Regarding Waste Wood Combustion Facilities
• What are the major issues affecting the decision to burn
processed waste wood at a combustion facility?
• What issues affect wood fuel procurement by combustion
facilities? Are there different specifications for wood fuel
that is derived from the waste stream?
• What are the major types of equipment used to handle and combust
processed waste wo od?
6.1.2 Key Finding*
• The choice to use processed waste wood fuel ar combustion
plants is affected by several factors: specific fuel
requirements at facilities; the availability of wood fuel from
conventional sources; local air quality conditions and
regulatory familiarity with waste wood combustion technologies;
and, the ability of combustion equipment to handle and burn
various types of fuels,
• Wood fuel specifications, particularly for processed waste wood
that may contain treated wood, are becoming more specialized.
Conventional fuel contracts usually specify only the delivered
price and acceptable moisture and ash content. Increasingly,
fuel procurement managers are focusing on physical and chemical
tests to determine the types and levels of non-wood material ill
wood fuel. In addition, they are offering tiered price
schedules for varying fuel qualities,
• Two major types of combustion systems, grate-fired and fluidized
bed, are used to burn processed waste wood in the study area.
There are substantial variations in the performance, size, grate
and boiler design, excess air requirements, level of add-on
pollution controls,' and other factors among the combustion
systems indicate that combustion units can be carefully matched
to specific fuel characteristics.
• Wood fuel derived from wood in the waste stream is used
primarily by large stand-alone power plants or large industrial
cogeneration facilities with boiler capacities greater than 100
MMBtu/hour. These facilities generally experience economies of
scale that allow for the use of high efficiency control
equipment for an array of pollutants,
6.2 Issues Affecting Waste Wood Cambuation
A variety of factors affect the decision to process and use waste
wood for fuel and the selection of equipment at a wood-fired facility
including: availability, price, and characteristics of the waste
wood; design, engineering, performance, and cost of combustion
equipment; and regulatory issues, among others. For facility
operators, uncertainty about the availability and price of waste wood
with consistent combustion characteristics can affect fuel and
technology choices. For regulators, uncertainty about combustion
performance at facilities that burn processed wood can be a major
6-2
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factor during the permitting process. Interviews with facility
operators and regulators indicate the following concerns and issues
regarding the processing and subsequent combustion of waste wood for
energy.
• As with any steam, heat, or power generating facility, the
overall issue affecting the selection of combustion equipment
depends on the purpose of the facility. Technology selection is
most strongly influenced by such factors as the size and scope
of power sales contracts for power plants, the ability of
equipment at existing facilities to convert to and burn
alternative fuels, and the process steam demands in industrial
settings. Factors that affect a plant's interest in using
processed wood are typically secondary to these other issues.
However, the availability and price of processed wood nay be a
critical factor in the overall economic viability of a facility.
• Most, if not all, facility operators believe that combustion
equipment that is commercially available and commonly used at
wood-fired facilities is capable of burning processed wood in
compliance with existing air and ash regulations. Their
experience operating facilities indicates this is true if the
waste wood is processed well, good combustion practices are
followed, and sufficient stack controls are used.
• The familiarity of regulators with the performance, air
emissions, and ash contents of combustion systems that burn
processed wood has a major affect on the permitting and
development of facilities. Many states do not have specific
standards for facilities, especially those that plan to burn
treated wood. Facilities are often reviewed on a "case-by-case"
basis.
• Ambient air quality in the region where a wood-fired facility is
located greatly affects the type of pollution control equipment
used and, in some cases, the type of furnace or boiler used. As
discussed below, air quality problems and regulations in
California have prompted the construction of several fluidized
bed systems. Emissions standards and the performance of
fluidized bed systems are shared through a "BACT clearinghouse"
of state and regional air quality regulators that helps
determine required performance standards for new facilities
(Terry, 1991).
• When adapting existing wood-fired facilities to burn more
processed wood, facility operators are more likely to modify
their fuel handling, screening equipment, or furnace combustion
controls rather than the actual combustion equipment due to the
concern about fuel cleaning, sizing, and mixing {Joseph, 1991),
In addition, the lower moisture content of processed wood
compared to other wood fuels may require adjusting air-to-fuel
ratios or adding a NO- control system.
• Most wood-fired facilities are not designed to burn only
processed wood. They are usually designed to burn one or more
types of wood such as harvested wood, mill residue, and
agricultural residue in addition to the processed wood.
Although many plant operators would like to increase their use
of processed wood, most facilities have a limit on the amount of
dry, finely sized material that can be burned due to the need to
6-3
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minimize wear on combustion equipment and maintain permit
compliance fKarakesh, 1991).
• Economies of scale affect whether combustion facilities can use
processed wood fuel. As previously discussed, this is due to
the more detailed regulatory review and more complex permitting
process often required, if a facility intends to process and/or
burn waste wood rather than just harvested wood, mill residue,
and agricultural residue. It is also due to capital and
operating costs associated with the equipment needed to control
air emissions and ash contents.
• Many small, older industrial facilities that burn wood fuel are
equipped with simply a cyclone or multicyclone for particulate
control. They may also monitor opacity and carbon monoxide to
check combustion efficiency. These facilities typically burn
harvested wood or mill residue generated on-site. Regulators
usually view these feedstocks as predictable, uniform, and
appropriate for combustion for energy. However, small or medium
size industrial facilities may not have the resources to modify
their facility to meet regulators' concerns about the combustion
of processed wood obtained from multiple off-site sources. The
modifications could include adding continuous stack emission
monitors, fabric collectors, and/or electrostatic precipitators
and N0X control systems.
6.3 Wood Fuel Procurement
Currently, the use of processed wood for fuel is most common at stand-alone
wood-fired power plants developed by independent power producers (IPP), and
large industrial facilities. Most of these facilities use at least 100,000
tons per year of wood, a portion of which is processed wood. Several fuel
suppliers and numerous sources of waste wood may be used to maintain an
adequate supply of fuel at the facilities. Typically, major wood-fired
facilities using processed wood rely on ten lo twenty sources of fuel although
they may be served by only one or two brokers. A wood fired power plant in
Calif ornia, for example, relies on more than 50 different fuel suppliers. A
pulp and paper mill in Minnesota burns mill residue, whole tree chips, coal,
and railroad ties (processed on-site) hauled from as far away as Washington
state
-------
continue to be poorly managed, overstocked with low value species, and the
true resource potential for timber will not be realized.
Opportunities to acquire wood from the waste stream at no- to low-cost can be
an important incentive for combustion facilities to use processed wood. As
landfills become full and it becomes increasingly expensive to permit and site
new ones, there is growing interest in processing bulky waste, such as wood,
for fuel and other uses. la some locations, processed wood is available for
fuel at no or low cost due to the avoided cost of not having to pay for
disposal of the material in a solid waste facility. The waste generator
and/or hauler has saved money, by recovering the wood rather than paying
tipping fees. In some locations, the avoided tipping fee is larger,than the
total cost of processing the wood and delivering it to a combustion facility.
Facility operators also use processed wood due to its lower moisture content
and higher heat value.
6.3.2 Wood-Fired Industries
In addition to power plants, numerous wood products industries burn mill
residue on-site that includes a mixture of wood waste, such as bark, planer
shavings, plywood, particleboard, painted wood, laminated wood, and stained
wood. These industrial boilers are used for process steam, space heating,
water heating, and kiln drying. They sometimes cogenerate electricity that is
used on-site and/or sold to an electric utility. Two important differences
exist between large wood-fired power plants that burn significant amounts of
waste wood and smaller industrial boilers that burn mill residue. These
differences directly affect the opportunities and constraints associated with
modifying the facilities to burn processed wood for fuel.
The first difference is that industrial facilities that burn mill residue
produced on-site have substantial control over their fuel source because they
are both generators and consumers of a relatively homogeneous supply of waste
wood. This means that the combustion system at these facilities burns a
specific, and fairly constant type for mix) of fuel. There is reduced
potential for changes in combustion efficiency and air emissions due to the
consistency of the feedstock. Although an industrial boiler may burn treated
waste wood, emissions control and boiler efficiency can be relatively
predictable assuming a consistent fuel source and good combustion practices
are used. Sometimes referred to as an "enclosed" system of fuel generation
and consumption, this has important implications for the regulation and
permitting of facilities that burn processed wood (Getz, 1591). Several
states, such as New York, regulate industrial boilers that burn mill residue
produced on-site less stringently than a combustion facility that relies on
diverse sources of fuel obtained off-site (N.Y.,D.E.C., 1991).
The second difference concerns the economies of scale that affect the degree
to which industrial wood-fired facilities can rely on diverse sources of wood
fuel from off-site sources. The regulatory scrutiny and expense is magnified
for off-site sources of wood fuel that may contain chemicals or preservatives.
Large wood-fired power plants frequently conduct fuel sampling and testing
programs to maintain fuel quality and control the frequency of equipment
maintenance and repairs. The expense involved in operating fuel sampling and
testing programs can limit the number of industrial facilities interested in
burning waste wood processed from multiple sources located off-site. It is
essential that waste wood processors be able to provide fuel that consistently
meets combustion specifications for size, moisture content, Btu value, and
acceptable levels of nor.-wood and ncn-combustible material.
6.3.3 Wood Fuel Procurement
6-5
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Specifications and techniques used for procuring wood fuel have a significant
impact on the ability of wood-fired facilities to meet combustion
efficiencies, air emissions standards, and ash contents established by federal
and state environmental regulations, especially facilities that use processed
wood as part of their feedstock. Procurement strategies vary, depending on
the type and quality of fuel needed, requirements of the combustion system,
and wood fuel prices. Some wood-fired facilities operate an ongoing fuel
testing program to assure that moisture content, heating value, and the
percentage of non-wood material is within acceptable limits (Schroeder, 1991).
At other facilities this is unnecessary. Many boilers at wood products
industries, for example, burn fuel that is a byproduct of the manufacturing
process. The fuel characteristics are well known at the facilities, since
manufacturers are 'familiar with working with specific species and grades of
wood.
Wood fuel procurement at wood-fired power plants can be sufficiently complex
to necessitate using either in-house or third party brokers for maintaining
fuel quality and supply. This is especially necessary if wood fuel is
obtained from diverse off-site sources that require individually negotiated
fuel contracts with each supplier. Contracts specify fuel quality for several
physical and. chemical parameters. In some states, such as California, it is
not uncommon for a wood fuel broker to supply several power plants
simultaneously. For each plant, the broker must provide a sufficient supply
and quality of fuel that meets the combustion and permit requirements of the
facility (Kaylor, 1991).
Relatively large combustion facilities that use professional fuel procurement
managers usually write their own fuel contract standards; however, air quality
permits may also contain specific language on the types of fuels that are
allowed to be burned. In air permits, unacceptable wood fuels are frequently
defined to be any type of "treated" wood; however, this term is imprecise for
many facility operators. During the past several years, regulators in some
states have become more specific about the types of waste wood products that
are acceptable for use as fuel (Buss, 1991}. In addition, air permits may
require operators of combustion facilities to maintain detailed records on the
types and amounts of fuel burned. This may be required to confirm, eligibility
for emission reduction credits or to demonstrate compliance with fuel
specifications in the air permit (Keest, 1991}.
Examples of recent wood fuel permit and recordkeeping provisions are contained
in permits for two fluidized bed wood-fired power plants in California. One
permit is for a 28 MW facility; the other is for a 30 MW facility. Both
facilities bum a combination of harvested wood, agricultural residue, and
processed wood {referred to in the permit as "urban-wood"). Condition A
specifies acceptable wood fuels for the 28 MW facility. Note the broad range
of acceptable "urban-wood" wood fuels. Condition B specifies wood fuel
recordkeeping provisions for the 30 MW plant.
(AS"...Fuels for the boiler shall be limited to the following untreated wood
fuels without prior District approval:
1. Orchard prunings and removals,
2. Urban-wood fuel (secondary wood); clean, new construction
waste; tree and brush trimmings; wood-product industries
(cabinet makers, log cabin and prefab structures,
furniture mfg., boats and boating mfg, mi11work mfg.,
sawmills and pallet mfg.),
3 . Stone-fruit pits,
4. Assorted nut shells,
5. Whole, tree chips.
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6. Natural gas.
(B)". ..The applicant shall maintain records of fuel acquired and the mass of
fuel burned on a daily basis, including records of compliance with fuel blend
requirements. In addition, daily records are required of mass, type# and
geographic origin of the biomass received, accompanied by certifications by
the fuel supplier and applicant that any creditable biomass has been
historically burned openly in the basin."
These permit conditions demonstrate the importance of fuel procurement
practices, particularly for facilities that intend to burn significant amounts
of processed wood, and "treated* wood. Despite regulatory requirements and
permit conditions, primary fuel specifications are usually determined by the
type of combustion system and the expected "woodshed" (or supply region) of a
proposed combustion facility. Some combustion systems are more sensitive to
dirt, moisture, and other non-wood materials than others. The selection of
the combustion unit relies strongly or the expected amounts and types of
fuel{s} (Hanson,1992J . Table 6-1 compares typical fuel values for a variety
of wood fuels. Differences in combustion systems are discussed in Section
6.4.
6.3.4 Wood Fuel Specification*
As noted above, both regulators and combustion facilities are placing more
emphasis on fuel quality and composition. At some facilities, fuel content
standards are explicitly stated as permit criteria in order to ensure
performance standards for the control of stack, gas emissions. At other
facilities, the primary check on fuel content and acceptable limits of
non-wood and non-combustible material is found in fuel contracts with specific
suppliers.
Major issues addressed by fuel specifications developed by combustion
facilities are discussed below. In addition, Appendix F provides examples of
wood fuel specifications used by two wood-fired power plants in the study
area. The facilities use a mix of harvested wood, mill residue, agricultural
residue, and/or processed wood. Chapter 7 discusses in detail the combustion,
chemical and environmental properties of "treated" and "clean* wood fuels,
The following discussion indicates the importance of these parameters in
designing and operating a combustion process.
6.3.4.1 Wood Chip Size
The first specification in a fuel contract usually addresses wood chip size
because uniform particle size increases combustion efficiency and helps
achieve consistent emissions. Generally, wood fuel that varies significantly
in size causes uneven rates of combustion. Excess fine particles can cause
unpredictable, spontaneous combustion above the combustion bed. Oversized
material may lead to poor combustion. Maintaining consistent fuel size is
also important in minimizing bridging and blockage in fuel handling systems
and in ensuring steady delivery of fuel to the furnace. Unpredictability in
fuel delivery can result in damage to refractory and boiler components.
Combustion systems are matched with the size of the fuel. Grate burners
usually use fuel that ranges in size from no less than 1/8-inch on any side up
to a maximum of 5 inches on any side. Preferred ranges are one to three
inches in size, or approximately eight cubic inches of material. Air permit
standards may also establish a limit on the percentage of fine wood (i.e.
material that is less than 1/8- or 1/4-inch) that is acceptable to burn,
especially for stoker-fired systems using pneumatic or other mechanical
feeding stokers. File burning, grate systems may accept a wide range of fines
6-7'
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and bulky wood material up to several feet in length. The primary limitation
for pile burning facilities is the size of the feed chute or stoker mechanism,
since the fuel is "piled" onto a mass-burn combustion bed with less regard to
size or shape.
fable 6-1. Characteristics of common waste wood fuels".
Harvested
Wood
Primary MiB
Residue
Secondary MS
Residue
Processed
Wood
Refuse-Derived
Fuel (RDF) (b)
Sources and
Types
Logging,
landclearing,
landscaping
Hogged bark,
trim slabs,
planer shavings,
sawdust
Sander dust, planer
shavings, sawdust,
pulverized scraps
Municipal,
construction,
demolition, and
other commercial/
industrial sources
Separation and
processing of
combustible
portions of MSW
Moisture Content
(wet basis)
>45%
>20%
8-12%
10-30%
15-30%
Typical Particle
Size of Fuel
1.0-4.0'
<1.0-4,0'
<1.0*
0.5-4.0* ¦
Uniform pellets,
briques, or 'fluff'
Ash Content
1.0-3.0%
3.0-4.0% baric
0.1-2.0% other
0.1-3.0%
1.0-10.0%
5.0-30.0%
Typical Btu's
per Pound
4,500
4,500
7,500
6,000-7,500
5,000-6,000
Typical Combustion
Systems Used
Grate Burners,
Fluidized Beds
Grate Burners,
Suspension Burners,
Fluidized Beds
Suspension Burners
Grate Burners.
Fluidized Beds
Grate Burners,
Fluidized Beds,
Rotary Kilns
(a) From Campbell, A.G., 1989; Junge, D.C., 1989; and Tillman, DA, 1991.
*#
(b) RDF is listed for comparative purposes since it is technically considered a solid waste fuel, not a waste wood fuel.
RDF consists of the separated, combustible portion of municipal solid waste that may contain varying amounts of
waste wood. This fuel is generally prepared by a densification process that results in a uniformly sized, easy
to handle fuel pellet, brique, or fluff material. RDF, however, is known to contain much higher concentrations of
non-wood contaminants, such as plastics or metals, than waste wood fuel.
Combustion performance in fluidized bed systems is more affected by variations
in the particle size of fuel for two reasons. First, the high degree of
turbulence in fluidized bed systems tends to even out hot and cold spots
across the bed. Second, the fiuidized bed allows various sizes ot material to
"float" in the bed, until complete combustion is achieved. Fuel sizing
criteria for a recently built bubbling bed facility specifies that all wood
fuel must be less than six inches in size. At least 90 percent of the fuel
must be less than four inches, and no more than 25 percent can be fines of
less than one-quarter inch. Fuel sizing criteria can be more important in a
6-8
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circulating bed than a bubbling bed due to the higher velocities required in
circulating bed systems {Hanson, 1992 5.
6.3.4.2 Moisture Content CMC)
The moisture content of wood fuel is a critical parameter because moisture is
directly related to usable heat value, combustion efficiency, and furnace
design. In general, grate burners can be set up to tolerate low moisture
content fuel or high moisture content fuel. When the moisture content range is
established, the fuel feed must be relatively consistent within that range.
This means, for example, that a grate burner can burn wood from 10 to 25
percent MC, or froir. 45 to 60 percent. MC (wet basis) . Alternatively, both
moisture content fuels can be burned together as long as the fuels are
sufficiently blended. Some wood-fired facilities purposely seek an "average"
fuel moisture content, such as 35 to 40 percent, by mixing dry processed wood
and wet, harvested wood (Fitzgerald, 1991). It is important that dry and wet
fuels be well mixed in grate systems because slagging, clinkering, and swings
in stack gas emissions can result from an abrupt and uneven introduction of
fuels containing wide variations in moisture content.
Recent fluidized bed combustion technologies allow substantial
flexibility in wood fuel types because the process of pyrolysis and heat
transfer are dramatically different in fluidized bed systems than in grate
systems. Fluidized bed systems are generally less susceptible to changes in
combustion performance caused by a changing moisture content in the fuel.
Turbulence in the combustion bed causes high rates of heat exchange between
the fuel and the bed which prevents slagging and ensures rapid drying and
pyrolysis. The moisture specification for one fluidized bed system, that burns
processed wood, for example, ranges from 8 percent to 30 percent (Hanson,
1992).
Fuel contracts usually stipulate acceptable moisture content in fuel in one of
three ways. The simplest way is for a facility to set an absolute limit, such
as 60 percent, on the moisture content of any wood fuel to be accepted. The
facility may also encourage and contract fuels with lower moisture contents.
A second method establishes a ceiling for any single delivery. However, the
contract may also prescribe that deliveries meet a weighted average for
moisture content on an annual or monthly basis that is lower than the ceiling,
The third method is to establish individual moisture standards on the basis of
the type and source of fuel delivered. An example Is a 25 percent moisture
content limit on processed wood compared to a 44 percent moisture content
limit for harvested wood used by a power plant in Pennsylvania (Viking Energy,
1931).
Standards for moisture content are enforced several ways. One way is through
contracts with fuel suppliers that establish fines for delivered fuel that
exceeds the acceptable limits. A second way involves weighing trucks before
and after they unload fuel. The weight of the loaded fuel and truck is
compared to the empty weight to determine the weight of the delivered wood,
The moisture content of the fuel is determined by drying a sample in a
microwave oven according to specific test procedures. After subtracting for
the water weight, fuel payments are made on a bone-dry basis (Schroeder,
1991), A third way is to scale fuel prices according to varying moisture
levels. Under this system, moisture specifications may also be linked to
Other wood fuel characteristics, such as fines or ash content. Regardless of
the mechanism used to enforce moisture content, combustion facilities usually
reserve the right to either reject loads if moisture standards are not met, or
to assess monetary penalties,
6.3.4.3 Physical and Chemical Composition
6-9
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Combustion facilities may also be required to sample and test their fuel on a
regular basis to monitor fuel quality from individual suppliers. For example,
'one proposed facility that planned to use 40 percent of its feedstock from
processed wood was required by its draft permit to test fuel for physical and
chemical criteria including daily and monthly samples for ultimate and
proximate analyses, and total metals tests. In addition to size and moisture
content, tests included a vapor detection test for volatile organics.
Physical and chemical content specifications were developed for fuels with
moisture contents of 2 5 percent, 4(3 percent, and 50 percent. The
specifications are listed in Table 6-2 and were introduced during permitting
of a facility in Connecticut. The fuel specification pertaining to processed
wood is presented in the column for fuel containing no more than 25 percent
MC. The metals standards apply to all types of wood fuel to be accepted at
the facility. It should be noted that the frequency and extent of testing
requirements implied here are not typical. Furthermore, plans for this
facility have been withdrawn.
Standards for non-combustible material are usually specified in terms of
acceptable ash content. As shown in fable 6-2, a higher ash standard for
processed wood is listed Cup to 10,4 percent by weight} than for other types
of wood fuel. However, it is difficult to test fuel when it is delivered for
the amount of non-combustible material that will be present in the ash when
the material is combusted. Yet, failure to control excessive non-combustible
material in fuel can result in accelerated corrosion of fuel handling,
furnace, and stack equipment. It can also affect combustion efficiency by
deterring complete combustion and promoting clinkering and slagging in the
fuel bed. Some facilities require that suppliers provide ash and
ultimate/proximate tests, prior to accepting fuel for delivery. This is more
common if the combustion facility does not have previous experience with the
supplier. When, an initial delivery is made,'the supplier and combustion
facility may agree on a regular testing program.
Alternative tests for non-combustible material are used at some facilities to
catch "dirty" loads before they enter the combustion unit. One method
consists of rinsing a measured sample of fuel and weighing the residue
material. If, for example, the residue material consists of more than 0.01
percent of the total weight of the sample, the fuel is rejected (Karakesh,
1991; Hanson, 1992), Another method uses a dry screening process to shake off
the fine dirt and other residue. Similar to-the wet test, this sample is
compared to the overall weight of the fuel sample,
6.3,4,4 Potential Contaminants
Controlling for and testing fuel for unacceptable levels of non-wood chemicals
or preservatives is more difficult than testing for size, moisture contents,
and physical and chemical composition due to the range of possible
contaminants in wood fuel, ana a lack of quick and inexpensive test methods.
One exception is the proposed vapor detection test used for volatile organics
previously mentioned. However, it is difficult to discern, for example,
between old painted wood containing high lead concentrations, and wood
containing newer water-based paints. Several testing approaches may be needed
to screen unacceptable treated wood from fuel used at a combustion facility.
Some mechanisms have already been discussed, such as testing and monitoring in
the permit process. Mechanisms for controlling fuel contamination that apply
specifically to fuel procurement are listed below. Two or more of these
mechanisms are generally used in fuel procurement negotiations.
» Fuel contracts usually refer to the right of a combustion
facility to refuse any hazardous waste designated by RCRA
6-10
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fable 6-2. Example of wood fuel specifications used by a proposed wood-fired
power plant®.
A. Physical Contents.
Ultimate analysis, percentage by weight
Moisture
25
40
50
Carbon
33.6 - 39.8
26.9 - 31.9
22.4 - 26.6
Oxygen
25.0 - 33.4
20,8 - 26.7
17.3 - 22.3
Hydrogen
4,0 - 5.0
3.2 - 4.0
2.7 - 3.3
Nitrogen
0.06 - 1.1
0.05- 0,9
0.04 - 0.8
Ash
0.6 - 10.4
0.5 - 8.3
0,4 - 6.9
Sulfur
0.02 - 0.3
0.02- 0.25
0.015- 0.2
Nominal size of fuel to be burned*.
Acceptable wood fueli
Unacceptable wood fuel;
2 inch by 2 inch chips
Whole tree chips and sawdust from
forest management, land clearing
operations, sawmills, and wood
product manufacturing.
Processed wood fuel sources from
construction activities which have
been sorted to remove non-wood
materials.
Railroad ties, telephone poles,
marine pilings, demolition wood,
treated wood.
B. General Wood Fuel ...Specification for Metals Content., {ppm by weight)
Arsenic
Cadmium
Mercury
Nickel"
Silver
Chromium
Copper
Lead
Barium
Antimony*
Iron6
Selenium
Chlorine
Sulfur
15 * 00
1.3
0.20
1,60
17.00
20.00
244,00
47.00
4.40
0 . 09
0.14
Notes:
a. This specification was developed as part of a permit proceedings for a
wood-fired power plant that intended to burn 40% processed wood.
b. These metals were not analyzed.
6-11
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Subtitle C, or contaminated wood waste that fails EPA toxicity
characterization tests.
• Fuel contracts may single out specific wood product types, such
as wood containing CCA or pentachlorophenol, as unacceptable for
delivery.
• Depending on permit requirements, fuel specifications may
disallow any type of "treated" wood to be accepted at the
combustion facility due to the risk of obtaining excessive
amounts of treated wood fuel.
• • Fuel contracts nay set a visible standard for the percentage of
specific types of "treated" wood that may be contained in any
fuel delivery, such as no more than 5 percent of painted wood or
10 percent plywood (Kenedy, 1991).
• Similar to standards for non-combustible material, combustion
facilities may base their acceptance of fuel from a supplier on
results of comprehensive fuel sampling and testing.
• Fuel contracts may specify that wood from a particular source
[such as wood from demolition activities}, or wood stored at
particular sites (such as wood stored on a arsenic-contaminated
smelter slag pile) cannot be accepted (Leone, 1991).
• Fuel contracts may reserve the right of combustion facility
operators to perform unannounced inspections of processing
facilities to check on the types of wood accepted for
processing,
• Similar to other fuel criteria, monetary penalties may be
assessed for fuel contamination, or a combustion facility may
reserve the right to cancel a contract if unacceptable
contaminated fuels are detected,
6.4 Fuel Delivery, Storage, and Feeding Equipment
The fuel handling system used at a combustion facility greatly affects the
ability to use wood fuel, especially processed wood that may be obtained from
waste wood sources that contain non-wood contaminants. Several handling
systems exist for wood fuel burned in chipped form. All handling systems
consist of three basic components: fuel delivery and unloading equipment,
storage areas or buildings, and feeding equipment that provides fuel to the
boiler. A fourth processing component may also be included, if waste wood is
processed on-site for fuel. On-site processing equipment is discussed in
Chapter 5.
fwo major concerns affect the design of fuel handling systems at wood-fired
combustion facilities. One is maintaining an adequate supply of fuel to meet
the combustion requirements of the furnace or boiler. The second concern is
potential fuel supply disruptions that can result from excessive wear,
clogging, or bridging caused by handling equipment that is insufficient for
the fuel Is) being used. Other factors affecting fuel handling include the
size and rate of delivered loads of fuel, seasonality of certain supplies,
seasonal changes in physical composition of the fuel, and fuel storage
conditions (Tischler, 1991).
Different wood fuel types vary the handling equipment and techniques needed.
Important considerations include the angle of the conveyors, flow ability of
6-12
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the material, tendencies to compact, density of the material, tendencies to
bridge or "felt" {i.e. form a mat), arid the potential for dust and spontaneous
combustion {Vranizan, et. al.,1987). In cold climates, wet hogged fuel or dry
fuel that becomes wet can freeze into solid masses and cause handling
problems. Systems designed to handle dry, processed wood fuel must generally
be able to handle compaction and classification of fines, dust control, and
the potential for ignition. Processed wood tends to b« less stringy than wet
hogged fuel; however, construction and demolition wood has a tendency to form
long splinters that may encourage bridging on conveyors and in metering bins
(Welder, 1991), An advantage of fuel with a low moisture content (such as
processed wood} is that fuel drying equipment which may be used for wet hogged
fuels is unnecessary. Fuel drying equipment is usually placed in the fuel
handling line prior to fuel entering the fuel feed auger or metering bin.
Fuel handling systems can be either fully automatic or semi-automatic. At
facilities that generate their own mill residue, automatic systems may consist
of a system that conveys mill residue directly from a manufacturing line into
a fuel silo. Or, at facilities that obtain fuel from off-site, fuel handling
syscsms may consist of unloading bins or hoppers that allow delivered fuel to
be conveyed directly to screening equipment and subsequently to a fuel
metering bin (GLRBEP, 1986}, Automatic systems are typically used only when
fuel quality and consistency is assured.
Semi-automatic systems require operator control or supervision at key points
in the unloading, storage, and fuel feeding line. These key points are
typically the following;
• During fuel unloading, where fuel inspection and sampling may
take place,
• At sorting, screening, or chipping stations where the potential
presence of non-wood material may damage handling equipment,
• At the point where fuel is loaded onto a conveyor to begin the
fuel feeding process. This is necessary to make sure that an
even flow and composition of material enters the line.
• In the operation of equipment that places fuel into a metering
bin or into the combustion unit itself.- 10,000 to 50,000 cubic
foot silos or rectangular bins are typically used for fuel
storage by small industrial boilers. In larger systems, similar
sized silos and bins provide temporary storage to fuel augers
that meter fuel to the boiler {Grimm, 1985). These systems are
necessary for stoker-fired combustion units that require an even
flow of fuel for the spreading mechanism to function properly.
Other systems operate much differently, however. An example is
a pile- burning system that uses a grapple crane attached to an
overhead track. The track leads from an outdoor fuel pile into
an enclosed building that drops wood fuel directly into the
gravity chute that feeds the furnace (Tunney, 1991).
• In the management of fuel piles to assure a first-in, first-out
supply of fuel and to prevent fuel decay. Outdoor fuel piles
typically need to be turned every two to four weeks to minimize
buildup of moisture, loss of heat value, odors, and the risk of
spontaneous combustion.
• Where dust control systems are necessary, frequent watering or
ventilation equipment may be required.
6-13
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At some facilities, one or two people can perform nearly all of the functions
listed. At large combustion facilities, however, a person may be needed for
each function, especially if the facility operates fuel processing equipment
as part of the fuel handling system. Schematics of four fuel handling systems
are shown in Figures 6-1 and 6-2,
6.5 Combustion Equipment
Overall, there are five types of combustion systems that have the capability
to burn solid fuels such as wood, including grate burning systems, fluidized
bed systems, conventional suspension burners, rotary kilns, and advanced
suspension systems that use gasification.
Grate burning systems and fluidized bed systems are the two types of
combustion systems commonly used for wood fuel, especially at facilities above
100 MMBtu/hr. Typical grate systems include spreader stokers, underfeed
stokers, and pile burners. Fluidized bed systems include atmospheric bubbling
bed and circulating bed systems. Conventional suspension burners are
coinmonly used in small, wood-fired industries. The energy produced is used
for kiln drying or veneer pressing.
Rotary kilns and advanced suspension systems that use gasification have more
specialized uses, such as the combustion of pulverized coal, pre-dried wood,
solid waste, or hazardous waste. Rotary kilns are most frequently used in the
combustion of medical waste, hazardous waste, and other contaminated debris
{Tillman, 1991}. Advanced suspension systems that use gasification techniques
are designed primarily for coal; however, these systems are being actively
researched for both solid and liquid biomass fuel use in the future. Rotary
kilns and advanced suspension systems that use gasification are not discussed
in this chapter-.
6.5.1 Furnace nmd Boiler Design®
There are significant variations in size and design parameters between the
grate burning, fluidized bed, and conventional suspension burning systems.
Key differences in grate burning systems are in size ranges, type of grate
system, boiler design, level of excess air, fuel handling, and pollution
control systems. Variations in fluidized bed combustion systems are related
to the type of bed medium used, boiler design, air velocity, and fuel
handling.
A comparison of grate burning and fluidized bed combustion systems is provided
in Table 6-3. In addition, the major advantages and disadvantages of grate
burning and fluidized bed systems are compared in Table 6-4. As shown in the
tables, fluidized bed systems have advantages in the control of certain
emissions such as NO„. However, they also have high operating and maintenance
costs compared to grate burners. Figure 6-3 illustrates a grate burning
combustion system. Figure 6-4 shows a fluidized bed system.
6.5.2 Grate Burning Systems
There are four types of grate burning systems including: spreader stokers with
either fixed or traveling grates,* underfeed stokers; inclined grates; and pile
burners. Grate burning systems have been used for more than several decades,
and their design, operation, and maintenance requirements are well understood.
Numerous equipment manufacturers design, build, and instal1 grate burning
systems throughout the U.S. and Canada.
Grate burning systems are widely used at wood-fired facilities. Grate burners
are generally capable of burning wood fuels with a wide variety of moisture
6-14
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OVERS BOX
Dry Fuel Storage System
SLEWING •STACKEW
tNFWD' COWCYOR
^— bicmhass
/ FUEL NFEED
Automate Outdoor Fuel Storage
and Retrieval System
Figure 6-1. Examples of waste wood fuel handling systems (Vranizan, 1987).
6-15
-------
OUT
SELF UNtOADWG BULLDOZER
SEMITRAILER
FUEL PILE
l^iJ
Fuel Delvefy and
Retrieval System
fuel fho*i aojo«ims mill
Automatic Fuel System
Figure 6-2, Additional examples of waste wood fuel handling systems
(Vranizan, 1987) .
6-16
-------
and ash contents. Fuel may be burned on a thick-bed, such as in a pile
burning system, or on a thin-bed fixed, inclined, or travelling grate system.
Wood fuel is injected into the furnace from a either a gravity fed hopper, or
it is mechanically or pneumatically stoked by spreading fuel across the grate.
Stokers may introduce fuel from the top, side, or through the floor of the
grates.
6.5.2.1 Pile Burners
Pile burners are typically of the Dutch Oven type, and are most prevalent in
facilities constructed before 1940. Newer pile burning systems are patterned
after the Dietrich fuel cell design. Pile burners are usually sized up to 50
MMBtu,'hr heat input. The grates may be fixed-horizontal or inclined. They
are usually fed by a gravity feed chute from a surge hopper or other type of
metering bin. Pile burners are two-stage combustion systems where charring
and gasification takes place in a primary combustion chamber and volatile
gases are burned in a secondary chamber.
One type of pile burner, the WeiIons fuel cell, is used in railroad tie
combustion. This is a two-stage system made in various sizes for steam
production up to 60,000 pounds per hour ipph) on fixed, water-cooled grates.
Volatile gases are burned in a secondary chamber with secondary air. This
arrangement prevents fuel particles from burning in suspension and lowers
particulate concentrations in the stack gas (Campbell, 1989). The fuel cell
has a rated efficiency of 65 to 75 percent.
6.5.2.2 Spreader Stokers
Spreader stoker units burn fuel in two- to four-inch beds on top of fixed or
travelling grates. Grates are usually air-cooled for boilers up to 20,000 pph
and water cooled for larger sizes. The largest systems { larger than 100
MMBtu/hr) use pneumatic fuel stokers and travelling grates which deposit
bottom ash into an ash sluice or conveyor system {JPR, 1984}. Large spreader
stokers that burn harvested and processed wood have been installed in sizes up
to 600 MMBtu/hr, with steam capacities of more than 400,000 pph of superheated
steam. An example is a facility operated by Washington Water and Power in
Kettles Falls, Washington. This facility uses a travelling grate spreader
stoker with a water tube boiler. The plant generates an average of 435,000
pph steam and approximately 50 MW of electrical generation.
Other stoker systems include medium-sized underfeed stokers that deliver fuel
through the grate intermittently with a ram or continuously with an auger.
The most common type of underfeed stoker uses a horizontal feed, side ash
discharge mechanism that requires manual cleaning. Underfeed stokers are rare
in sizes above 35 MMBtu/hr and are typically used when steam demand is less
than 100 pph {GLRBEP, 19861 . An example is the Ethan Allen Furniture Company
in Spruce Pine, North Carolina which burns mill residue and processed wood in
a 10,350 pph fixed-grate boiler. Fuel is fed by an air-cooled underfeed
screw.
6.5,3 Fluidized Bed Systems
There are three types of fluidized bed combustion systems including;
atmospheric bubbling beds; atmospheric circulating beds,* and pressurized fluid
beds. Both the atmospheric bubbling beds and circulating beds are
commercially available. The pressurized fluid beds are in research and
development. The use of fluidized bed systems for wood combustion began in
the 1980's, although fluidized bed technologies have been used for coal for
many years. They are increasingly common at power plants that plan to burn
significant amounts of processed wood and agricultural wastes. Fluidized bed
6-17
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Figure 6-3, Schematic of a spreader stoker (Boubel, 1977).
Convection
section
Water
want
X
BofMe
tubes
Evaporator
section
Primary
cyclone
Secondary
particulate removal
E«houst
Heat recovery
section
Water
wails
Ash.particulates
• Sui'cte.csh
Preheater. suoemeater
or rehecter section
Distributor olote
Limestone
or
dolomite
Figure 6-4. Schematic of an atmospheric fluidized bed combustion system
(Murphy, 1977) .
6-18
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Table 6-3. Overview of major types of combustion systems used to burn
waste wood fuel*".
TYPf Of COMUITION SfSTB
GRATE lURKRt FLUIOIZEO KD BUSKERS
Thin-lad Thick-led Att»«ph«ffe Auaoepheric
Stoker $ytte«* Pita Burners Rubbling Bed Circulating Bed
Typical
Site Range*
Travelling-grate underfMd:
10-35 Wtttu/hr
Stationary-grace undtrfaadi
10-20 MHRtu/hr
Stationary-(rate overfeed:
50-300 MMStu/hr
Travelling-grate overfeed
50-300 mttu/hr
Dutch Oven
« 50 MWtu/hr
Weltena or Dietrich
fuel call
< 50 MtuAr
15-500 mmtwkr
10-500 MWtu/hr
•oiler De*ign*
Vertical watertutie:
{watcrwatl. Hater dnJt)
25,000 - 600,000 pph
Kor'iontai firetube:
< «,000 pph
Tuo-stage coafcuation in
natertube or firetvbe
Vertical, uatertube with flue'
ga* recirculation
Grate Design
Fixed, inclined, travelling;
Air or water ceo lad;
Pinhole, vibrating, or during
FUed or inclined;
Air or water cooled;
Vibrating or dumping
Perforated Grate
Perforated Crate
Type of
Itdtir Syttcai (c)
Overfeed or underfeed
pneuaatic raa, aecfcanical
auger, ftp paddle
Gravity feed chute or
underfeed auger
In-bed pneuaatic, ***« a* IF!
ln-M_ auger feed
Overfeed aechnieal or pnauastic atoker
Typical fuel
Moisture tang*
10-55X
4WSX
0-651
0-6SX
Typical Steeaing
Range
Underfeed *tokrr:
< 100.000 pph
Overfeed/stationary grate:
to 450,000 pph
Ov*rf«ed/fnelInad-travel ling:
Lf) to 700,00(1 pph
Bwteh Oven; < 50, MO pph
Fuel cell: < 60,000 pph
Flat/travel ling grate:
up to 150,000 pph
Inclined grate*:
up to 500,000 pph
50,000-300,000 pph
!00,000-250,M0 pph
typical Fl*e»
Tesperatwre
1,800 - 2,600 deg.F
1.500 • 2,500 deg.F
1.500 - 1.750 deg.F
1,500 - 1,«» (tag.F
Contention
Efficiency Ml
60-80X in older unit*
80-99% in newer unit*
~5-65X Dutch Oven
60-80X Fuel cell
90-97*
95-99X
Typical Air Flott
Distribution
Gas velocity 15-22 ft/«e«.
(1:1 ratio underfire/overffre)
10-20 ft/sec.
2-7 ft/see 15-30 ft/*ec
{3:1 ratio uiderfire/overfIre)
(continued)
6-19
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Table 6-3. Overview of major types of combustion systems used to burn
waste wood fuel (continued).
GMTE «»£¦$
FUI1DIZE& BED Mills
Thin-led
Stoker tyitw
Thick'lad
Hie turners
Ataospherlc
lubbllng Ird
Ataospheric
Circulating hd
Air Umt Control'
1% Excni Alr>
2S-S0X
Typical Rang* of 1.25 - 1,50
Stoichiometric latio <•)
50-1001
20-25X
1.31 - 1.40
10-20X
1-35 • 1.4#
Typical teller
TumdoMn tat to (f)
*•5:1
5:1-10»1
1:1
3:1
Typical Stack Cm
Control* (d)
Ash Hand! iri®
Syscta
Percent Ash
8 i«ri but ion
Cyclone or iuI ri cyclone
CEK for Opacity, 60
Cyclone, Kulticyelone,
Wet or Dry ESP
Urea or Aanonia Injection for HOx
(non-catalytic reduction)
Liaestone Injection for SOx
CEK for MOx, CO, C02, 02, SOx
KM, opacity, NMX, and voc'i.
Exxon thermal 0e-»0x
Pneuastic and aechanical conveyor* Manual collection typical
for fly and bottoa ash, central
conveyor to aiio. Saall systems My
us* nanual collection procedures
50-7OX flyash
30-SOT bottoa ash
S0-7DX flyash
30-SOS bottoa *ih
pollution equipaent for IPI and CM:
Cyclone or Hulticyclorte
Uet or Dry ESP
Fabric filter lashouse
Urea or Aaaaania Injection for Mr
(non-catalytic reduction}
Uaeatone Injection for so*
CEH for KOx, CO, C02, 02,
HQ, opacity, WW, and VOC'a.
Exxon then* l De-»0x
Cry, drag chain conveyor*, sere*
conveyor*, central transfer
conveyor, ash storage silo.
?5X flyash
25% bo(ten
ash
75* flyath
25X bottoa .
<•) tascd o« Intonation 1rm Tillaan, O.A., tW1{ Tillnan, O.A., 1981; Croat lake* It eg i one! Hawaii Prograa, 19*6;
•ortheast Regional lioaess Prograa, 1984; Criaa, 1985; Jmge, B.C., 19«9; Yandle and lot, 1990; WIMwta and
SINbeck, 1990; Caapell, A.6., 1989 and; Itlay Stoker Corporation, 1992.
(M Suspension burner* arc not prof fled here, although they aay be used to burn certain special I zed types of waste Mood.
These system typically use sawdust or dry, pulveriled aill residue as fuel In snail industrial settings {« 50 MMBtu/hr).
They do not typically utilize source* of recycled mite wood.
tc> The major differences in grate burners relate to tie fuel feeding or stoker aechanisa, and the design of the grates.
Ml Contention efficiency describes the percentage of fuel burned with the aaount of fuel supplied. It typically represents
the aaount of residual unhurried carton. Thermal efficiency, however, expresses the total heat loss froa comtxation due
to factors such •• Moisture in the fuel and air supply, losses through dry stack gases, and losses froa unturned carbon
in the ash.
{*) Stoichioeietric ratio describes the condition at which the air-to-fuel ratio is such that alt eoafcustible products
*r«t coapletrd burnad with no oxygen raaaining.
<*> turndown ratio indicates the ability of the boiler to operate efficiently at less than aaxiaua design loads.
* tunrdonn ratio of lit, for esasple, aeans that a boiler can operate efficiently froa 20X-100X of capacity.
ff) Thij only lists the types of control equivalent uaed. Fe«, if any, systeaa employ all these control devices
limjltaneously. Continuous aaissiona aonitoring {OEM) is typically prescribed by air quality perai ts for najor
new wood-fired eoetoustion facilities. These are typical stack gas pollutants that facilities aay be required to
•onitor under Eheir sir quality peraits.
6-20
*
-------
Table 6-4. Comparison of major combustion characteristics between grace-
burning and fluidized bed waste wood combustion systems*,
PARAMETER
(MATE MINERS
FLUIDIIED KB BURNERS
1. Softer Designs
2.
Acceptable
fuel Type*
Wide itlKtlon e# furnace and teller design* that
allows developer* to match fual with other
operating conditions.
Ability ts bum wide variety of wast* wood fuel*,
however, wood fual mjtt be prepared and mixed.
Cofiring of wood and other fuels in spreader
•tokiri allowi for high steam production {up
to 700,000 pph.)
Fluidired'bed for wood cotfcuetion !i maturing fro* the
"first generation" itage in 1980'a. Modification fr«
probloM encountered in early de*ign> are underway.
Can bom will* variation in fuel moisture and
physical and eheaHcal content, toiler operation
¦table with fuel* between 0-50* moisture content.
Turbulence In the bad allows for rapid fual drying
and pyrolytl* •# fual.
3. fuel Bet(very
4. flame
Taaperature
5.
Efficiency
6. Combustion
Ifficiancy
Gravity overfeed, hortiontal mechanical auger,
or ynderfeed stoker mechanisa. For overfeed
aystema, air clarification of ft nee My
occur leading to rneven caatx«tion.
'.500-2600 degree* t
Higher thenaal efficiency froai hotter flaa*
temperatures than fluid beds. Large ataa* of
thermal refractory in many grata burner* aide
in preliminary drying of fuel.
Typically mechanical
60-801 for older unit*
50-99X for newer unft*
.of pneumatic stoker. Inconaiitanc
fuel site can load to uneven combustion.
1500-1S00 degrees f
Taaperature axceedence can profit clinker formation
that inhibit* bad efficiency and may require coetly
tyatM shut down and repair,
T(tarsal efficiency cenatrainad by liieita on
taaperature.
Nigh coafeuation efficiency (up to 99*) yielda
low CO and THG emission*.
T. Excesa Air Careful control of excess air necattary ainca
combustion efficiency and (tick amItsion* are
adversely affactad by poor air sipply and
distribution.
Exeats air it allowed to vary baaed on differing
fuel characteristics, however, bad taaperature
i* atabiIited by high mass of bad aadle.
S. Typical Wx
Control*
9.
Particulate
Control*
10. Air Toxic
Control*
II. Ash Collection
(ystem
12. Maintenance t
Operating
Higher flam teeperature contributes to higher
rates of KCx formation, however, recent LAEt fwnrit
standards for tfOx are comparable to fluid
Greater reliance on poat-codbuation control a,
CI.a. multtcyctone, ESP, baghouae) or fly aah
reinjectian then fluid!ted bad systaaa.
Imt flame taaperature reduces level of MOx e*iss(0M
M&C la at(o reduced through amaonia injection in the
fumaee rather than post-coafcust ion control*.
Nigh ceafeuation efficiency contribute* to lower
particulate formation. Typically utilixa multl-
cyctona and, whore necessary, baghouse. Fly ash or
char reinjectfen un«*6«*ary.
Dependent on fuel quality control, coafcution design,
and operator proficiency. Coaplax organic emission*
a. PCX'* or PA#)11) typical ly result fraa poor
¦¦--.tion and operating practices.
(i-
Mott spreader-stoker* have automatic ash collaction,
however, pile burners and (Mil system* aey require
shutdown for manual raking.
Potential ly high maintenance costs or. grate system
with high level of refractory and/or moving grate
parts. Generally higher availability than fluid
bed* and able to respond to load swings better.
•a Crate turners
Aah fonaation is critical in fluidited ba
of potential for fuaion. Use mechanical collection
systems far bottom ish.
Coaparatively high awintenance costs in first genamtian
units froa bed plugging, erosion in combustor and heat
exchangers, tow availability, and high power
blower motors.
m
from Langr, (. 1992; Mile* and Nilea, 1991; Nanaon J.I., 1992, JP1 Associate*, 19S4; Jchultt, 1992
6-21
*
-------
systems rely on the interaction and pyrolysis of wood fuel with heated
particles of sand or limestone to achieve combustion. The bed medium and fuel
are suspended by high velocity underfire air injected into the bed.
The two major types of fluidized bed systems, atmospheric bubbling bed and
circulating bed systems, are both used to combust processed wood, although
bubbling beds have been used more extensively. The modern era of fluid bed
combustion with processed wood began with a determination by California air
quality regulators in 1984 that fluid bed combustion represented the requisite
Best Available Control Technology for bi omasa combustion (Schultz, 1992}.
Their popularity, however, has increased since their application use fuels
with widely divergent physical and chemical properties.
However, use of fluidized beds in California for wood and Momass applications
was largely made possible because of high power rates inspired by PURPA
legislation (Miles, 1392}. Historically, wood fuel was available from the
pulp, paper, and forest product industry. Combustible solid waste from
agricultural wastes and urban wood wastes were also becoming a problem due to
decreased landfill capacity and open field burning. A dramatic increase in
the cost of fossil fuels due to the energy crisis of the 1970s created an
opportunity to reduce operating costs in these industries by using waste wood
and biomass fuels. Many wood conversion projects were undertaken to
substitute low cost waste wood and biomass for fossil fuels.
The energy market created by PURPA legislation in 1978, solid waste problems,
and air quality concerns were r.he factors that brought wood waste fuels and
fluidized bed technology together in California in the mid 1980's (Schultz,
1992) . However, the business of converting wood waste to energy was
predicated on making economic sense. Due to the combination of high capital,
operational, and maintenance costs of fluid!zed bed technology with rising
wood fuel costs (due to increased demand), most of the plants built in
California would not be economically feasible today with fluidized bed
boilers. Moreover, several of these plants are no longer economically viable
even under their existing power purchase agreements and have filed for
bankruptcy due to this combination of factors.
€.5,3.1 Bubbling Bed Systems
Bubbling bed systems are cylindrical, refractory lined chambers, filled with
an inert bed medium of 2-4 feet consisting of either sand, gravel, or
limestone. The bed media is fluidized by preheated under firs air that is
usually distributed through a perforated grate. Auxiliary fuel such as
natural gas is used to pre-heat the bed. When the bed temperature is
sufficiently high to support combustion, the auxiliary fuel is turned off and
wood fuel is introduced through a stoker mechanism. The high temperature of
the bubbling bed ignites the fuel and the turbulence of the bed allows for
rapid and complete combustion {Junge, 1989}. Non-combustible ash filters down
through the bubbling bed, and can be removed either continuously via the use
of a mechanical conveyor, or intermittently when the bed media is replaced.
Most commercially sized bubbling bed units use water tube boiler designs to
allow for superheated steam generation,
•The key combustion parameter with a bubbling bed is temperature, which is
controlled by varying excess air levels. If the temperature is too high, the
potential fusion of ash and bed material can "choke" the fluidizing process
and result in repairs. For this reason, fluidized bed systems operate at much
cooler temperatures than grate burning systems. An example of a bubbling bed
system is the 25 MW Ultrapower Chinese Station in Jamestown, California that
burns a combination of agricultural residue and wood processed from
6-22
-------
construction waste. The plant is powered by a bubbling bed with a nameplate
capacity of 208,000 pph steam at 1,350 psig and 955 °F.
6,5.3,2 Circulating Bed Systems
Circulating beds were developed primarily to correct for potential problems in
temperature control and ash agglomeration experienced by bubbling beds. Gas
velocities in circulating beds are strong enough so that both the bed media
and the fuel are physically transported as combustion takes place. If
temperature rises too quickly and threatens ash fusion, then the gas velocity
can be increased to cool the bed temperature {Junge, 1989), At the end of the
primary combustion zone, stack gases are separated by a cyclone and sent to
either firetube or watertube boilers. The remaining separated solids and bed
material are recycled back into the combustion zone. Temperature fluctuations
are more limited in a circulating bet! due to high turbulence, and high rates
of heat exchange between the fuel and the bed material. An example of a
circulating bed is the 49 MW Colmac Energy facility in Mecca, California which
burns urban waste wood processed from the Los Angeles area and agricultural
residue. This power plant is currently under construction. Once completed,
it will use two 232,000 pph circulating beds for steam, pressure at 1,255 psig
and 925° F.
6.5.4 Conventional Suspension Burners
Suspension burners that combust wood fuel are usually found in
primary and secondary forest products industries and are used where very fine,
dry fuels are available such as dry sawdust or kiln-dried rail! residue from
furniture, particleboard, or veneer manufacturing. In addition, large scale
pulverized coal systems using suspension technology currently provide roughly
half the electrical generation in the U.S. (Tillman 1991!. To the extent that
coal-fired power plants invest in fuel switching technologies, the co-firing
of wood fuel may be more prominent in these facilities in the future.
The primary feature of conventional suspension burners is that the fuel must
be dry (lass than 15 percent MC), very small {less than 1/2-inch), and evenly
divided. Fuel is injected pneumatically into the combustion chamber where it
burns rapidly in suspension, A refractory grate at the base of the chamber
may be used to catch excess ash or chips that settle without complete
combustion. However, grate cleaning associated with conventional grate
burning systems is essentially eliminated (Yandle & Loi, 1990}. An advantage
of suspension burning is high fuel combustion efficiency {up to 85 percent)
and the ability to respond quickly to changes in process heat or steam
requirements {Campbell, 1989) . Unless the fuel is already dry and prepared as
a result of manufacturing, however, a major disincentive to suspension burning
is fuel preparation costs. Certain types of suspension burners, such as
cyclonic furnaces, require a "wood flour" fuel consistency with particles
sizes of less than 1/8-inch. In addition, since fuel feed mechanisms are more
apt to foul with very small particle sizes, auxiliary fuels are need to
prevent flameouts, pulsing, or explosions in the combustion, chamber IJunge,
1989).
The use of suspension firing for mill residue and processed wood is typically ¦
limited to systems smaller than 50 MMBtu/hr. Wood-fired suspension burners
are not used for large scale power plants or industrial facilities. They have
more limited tolerance for differences in fuel moisture, size, and other
characteristics than grate or fluid bed systems. An example is the use of a
45 MMBtu/hr suspension burning system at the Hardel Mutual Plywood
manufacturing facility in Qlympia, Washington, that burns fine sander dust and
hog fuel from plywood trim scraps generated during manufacturing.
6-23
-------
6,6 Sunmary of Waste Wood Combustion Facilities in the Study Area
The following sections present three sets of summary information on waste wood
fired combustion systems. The first set consists of a series of three tables
(Tables 6-5 through 6-7} that compare combustion and control equipment used at
specific wood-fired facilities that born various types of waste wood- Systems
within three size classifications are compared- These are systems with a heat
input capacity of greater than 100 MMBtu/hr, systems between 10 MMBtu/hr and
100 MMBtu/hr, and systems smaller than 10 MMBtu/hr. The tables provide a
representative sample of the range of combustion technologies currently used
for combustion. The tables do not represent all the possible configurations
cf combustion technology that nay be used for wood fuel but emphasize
facilities whose feedstock includes processed wood, particularly fuel that may
contain non-wood contaminants.
Table 6-8 lists major wood-fired power plants in the study area that use
processed wood, mill residue, and agricultural residue in addition to
harvested wood for fuel. It does not include small- and medium- size
industrial facilities that burn primarily mill residue and harvested wood.
Such a list would be very long. For example, North Carolina alone has more
than 200 small and medium sized industrial boilers (SERBEP, 1986}, Lists of
these facilities can be obtained from state or provincial energy offices or,
in the U.S. from the Regional Biomasa Programs funded by the U.S. Department
of Energy,
6.7 Case Studies of Combustion facilities
Case studies of two waste wood combustion facilities are presented. Both
facilities burn a mixture of waste wood from construction, demolition,
municipal solid waste, agriculture, and wood"products manufacturing. The
facilities were chosen due to differences in combustion technology, location,
size, and operating parameters. The facilities are described anonymously, due
to agreements made concerning their participation in this study.
6.7,1 Fluidiz«d Bed Combustion Systems
This combustion facility is located in a federal non-attainment area for.
particulates and ozone. It is designed to meet a stringent level of emissions
control using modern combustion and control equipment. Permit requirements
contain specific fuel and stack'gas requirements. The combustion unit is a
bubbling fluidized bed system rated at 315 MMBtu/hr with 255,000 pound per
hour of steam at 1,350 psig and 955° F. The facility is designed to burn a
combination of processed {"urban"I wood, and orchard agricultural waste.
The combustor is 20 feet deep, 45 feet wide, and 56 feet tall. A forced-draft
fan supplies air to a preheater and the windbox for fluidization. Preheating
the bed is accomplished by using a 15 MMBtu/hr natural gas preheater. When the
combustion bed reaches sufficient temperature, fuel is supplied by an overbed
induced air feed tube. Overfire air is split from the forced draft fan outlet
and is adjustable to 35 percent of the total air supplied. Flue gas
recirculation is used for overfire air and fuel bed fluidization. According
to plant operators, flue gas recirculation allows the combustion of drier
fuels than would otherwise be possible.
This fluidized bed system also uses a patented bed draw-down system that pulls
residual non-combustible material such as nails or rock from the fuel. The
bed draw-down operates on a continuous basis with up to 10,000 lbs/hr of bed
material being cleaned and reinjected. The ability to handle large quantities
of non-combustible material allows the system to burn a higher amount of low
6-24
-------
Tables 6-5. Examples of technologies used by "large" waste wood combustion systems (>100MMBtu)'.
TYPE OF
FACILrTY
size
81 DM ASS FUEL
P£nMmeO(a)
WOOD FUEL USED
(tons/yearXti)
COMBUSTION SYSTBJ
type of poujutjon corimm
A, Power plant
355 MMB'u/hr; 32 MW(pbt$# 1};
24,5 MW (phase 2) to be buHt
AG, HW
AG, UW*
270,000
EPt bubbling iwWfcwd bad
wittt Hue gas recirculation
Multlcycfone 4 baghouse system;
Ammonia & Limestone Injection;
CEMS tor opacity, S02. N02. CO & 02.
B. Pulp & Paper Mill
(process steam)
2 boilers 270 MBtu/hr ea.
Combined steam 390.000 pph
TO, a, pit
75,000
Foster Wheeler spreader stoker.
travelling grate
Multlcyclone with ESP
CEMS tor NO*. CO, SOx
0, Power PUnt
3 boilers; 175,000 pph
steam each; 50 MW total
HW, CW, MR
pit, prtt
ISO,two
Zurn spreader stoker
with traveling grate
MuWcyctooe with ESP system
E. Power Plant
2 boilers; combined steam
427.520 pph; 49 MW total
AG, CM'.CTPI)
400,000
EH circulating MM bed
Cyclone, baghouse litter, air
preheatef, Ammonia and limestone
Injection, 5 Hue gas monitors
F, Power Plant
2 Boilers at 200.000 pph
each
MR. HW, CW
170,000
Babcoc* & Wilcox spreader stoker
Multi-tube mechanical collector
Electric gravel bed filter
O. Power Ptant
435.000 pph combined Seam
50 MW electric generation
HW, CW
mm
Combustion Engineering spreader
stoker, IraveWng grate
ESP wtm mechanical coiector
H. Power Rant
50 MW
300 MMBtu/hr
HW, CW
p«l
150-450,000
Zurn spreader stoker
ESP with mechanical collector
CEM tor opacity, NO*. C02 & 02.
1. Pulp & Paperboard
(process steam
and dryers)
M8Q MM8tu/hr heat
700,000 pph combined steam
30 MW electric (woodtuel portion)
HW, MR
233,000
6 Erie City fixed grate
1 Foster Wheeler travelling grate
Wet scrubbers with ESP
J, Power Plant
3 boilers 360 MMBlu/hr ea.
2 steam turbines, 45 MW ea.
HW, MR, RDF,
CW,(TR), pit
356,000
(per boiler)
3 spreader stokers
MuMcydooe with ESP
SNCR urea Injection
(a) A key to symbols used In this column Is found In Notes to Tables following Table 6-7
(b) Tills column represents the podlon of wood fuel consumption only. For price and fuel auppty reasons, large wood-Iked pmm plants frequently co-llr#
wood with coal, natural gas. oM, or refuse derived fuel (RDF).
-------
fable €-6, Examples of technologies used at "medium* size waste wood combustion systems (10-100
MMBtu)".
TV ft Of PACIUTY
«zt
SKMMffi FUELS
PEHMITIEDi*)
WOOO FUEL u*m
ft)
COMBUSTION 8V8TBU
Type Of P0UUTWW COKTW>U«
A. InduWiM
72,000 pph mm
OW.CW,MH,TH
80.000
KMW t-ataga. IncUnad i«ap~Jt(rt%
Flu« gaa «n»(bum#r
C©oan#T « boJkf
0, Mualrial
40 MM8tu/hr lumac*
MW, MR
14.000
McConnatl gfata burnw
Cyloona. mulllcyctorw. alactilo gr«««l b*d
31 MMBtu/h( htrnaca
(•ft on ply
18,000
Konua undMlaad atokar
Cyloona and labrte HUM, CEM for opacity
E Induxiial
tOO ,000 pph M«*m
AO. MR. UW. HW
Yank* Enatgy AuttUad Ml
Cog *n« allot)
7 5 WW #!«ctftc
pt*.P«
Wtckaa bollar
CEM
f. ImtattiM
45 MMBtWtll
MR
22,000
Coan auapanaton burnaf
MultieyoiGM
u.OQO pph aiMtn
ptiMwt
PaclHo Mai Ion ti«ub* Mt*f
A - CMmm*
Ufa rVWW rWlt
Two m MM8tu*t. 00.000' pph
UW.CW.OW.MR.HW
sa.000
Hunt MidMtMd mtm
Mutttc yclocf
MMm, 3 MW alKtrk
piMMjflLpMm
Huttt RfMtabt Mia*
H. M&Mii
27 MMbtcVhr
MR
Blgata* Haw) Drat* apfMdat
P?ocǤi St#am
M.OOO ppfi .1176 p.lQ
ptMrn
atokar wtlh MR? MM
1
«,000 pph
HW.Mft
25.000 wood
WaOona FM C*tl. **(«-too4»d
MiifUcyctoo*. CEM lor optdiy.
Cogeowstton
M«W*raM(ga
«iju
-------
Table 6-7
Examples of technologies used at "small" waste wood combustion systems (<10 MMBtu).
TYPE Of
FACILITY
SIZE
poiMrrrEO
BIOMASS FUELS
WOOOFUELUSCO
{tons/yaarXi)
COMBUSTION SYSTtM
' TYPE OP
PQLLLfTKX COWTttOL(S)
A. Industrial
10 MMBtu/hr
MR, HW
3500
Sylva 2-stage spreader
stoker, Inclined-reciprocating
grates
Oyeion*
B. Industrial
10 MMBtu/hr
MR
NA
Yorfc-8Nptn ffukMnd bed
7i > v« i—i i . ti l . M-i 1 jr. » ,»
iurn municyciont
0. Industrial
Heat
1.3 MMBtu/hr
MR
500
Q & S Mills model #K42
wtth mechanical stoker
E. industrial
219 horsepower
steam load
MR
2,500
{dry tons)
Blgetow pit burner
F. industrial
3.5 MMBIu/hr
150 HP steam
MR
NA
Ert* CMy Ifacad grata Dollar
Q. Industrial
6 MMBlu/hr
6,000 pph steam
HW, MR
3,000
(dry tons)
Suspension gaslfler with
Cleaver Brooks boiler
Flash collector
H, Industrial
9 MMSiu/hr
10,000 pph steam
MR
tm
15,000
Wellons fuel call with
Erie watertube boiler
Multlcyclona
1, Industrial
3,150 pphataam
m
tm
5,000
Dutch Oven with Erie City
lire tube
J. industrial
4,300 pph steam
HW
5.300
Energy Resource System pneumatic
spreader stoker with pinhole graie
(a) A key to symtwls used to this column is found in Notas lo Tabtaa following this Tub!®.
MA Not available
-------
!OTEStoTables6-^6-6^and^-J'
The following is a key to the wood fuel types in the tables. Symbols followed
by a"*" indicate waste wood terms actually used in the facility permit. Terms
in upper case, such as *CW" indicate general waste wod types acceptable for
combustion. Terms in lower case, such as "rr" indicate specific types of
"treated" waste wood or potentially "dirty" woood that are acceptable for
combustion.
AG «= Agricultural wastes
HW
Harvested waste wood
rr « Creosote railroad ties
UW = "Urban" waste wood
DW
=
Demolition waste
or utility poles
CM = "Commercial* Wood
wood
ply « plywood or laminated
wastes
CW
ca
Construction waste
waste wood
TR = "Treated" waste wood
wood
prt = particleboard or
RDF * Refuse derived fuel
MR
=
Mill residue waste
flakeboard
{e.g. pellets or
wood
(from manufacturing)
pnt * painted wood
fluff)
pit = pallets or shipping
crates
quality wood fuel, In-bed pollution controls include a limestone injection
system with a pneumatic 0.75 ton/hr metering system and blower, and an Exxon
thermal de-NOx system.
Feedwater is preheated to 400° F ana supplied to in-bed fin tubes and
non-finned vapor space tubes in the combustor unit. According to plant
operators, the finning of boiler tubes helps minimize tube erosion from the
fluidization process. Flue gases pass into a waste heat boiler and then into
a vertical screen tub section where the gas cools approximately 400" to about
1,350° F. Due to problems at similar unit*, this facility was re-equipped
with vertical superheater tubes in the boiler unit. Earlier units reported
problems with slag bridging in horizontal tubes. In addition, scot blowers
were installed to control ash buildup on the boiler tubes. From the boiler,
gas passes through a secondary economizer, multicyclcne, and primary
economizer. Flue gas is then mixed with preheated air, and passed through a
baghouse for final particulate control. The stack exit temperature is
approximately 320c P.
Design criteria for acceptable fuels allows a moisture content between 8.7
percent and 30 percent, although acceptable test ranges are up to 50 percent.
The desired composite fuel moisture is from 20 to 30 percent. Fuel must be
sized between one-quarter inch and four inches and the composite fuel ash
concentration should not exceed 3 percent, Processed ("urban"! waste wood
must consist of no more than 20 percent moisture and ash content is expected
to be no more than 2.5 percent by weight. Specific permit requirements
include limits on fuel content of nitrogen and sulfur based on higher heating
value standards. The nitrogen standard is 0.91 lbs/MMBtu. The sulfur limit
is 0.25 lbs/MMBtu.
Fuel handling equipment consists of several components. Two 60-ton truck
dumping platforms are used to receive incoming fuel. Two fuel receiving
hoppers consist of a 2,000 cubic foot covered hopper with a live-chain bottom
discharger and a similar 4,800 cubic foot hopper. The hoppers are followed by
a disk scalping screen, 250 horsepower swing-type haramermill, and belt-type
magnet. The fuel handling area also includes an extensive dust ventilation
system connected to several fabric filters.
6-28
-------
Table 6-8 Independent power plants that burn waste wood in the study
area' \
GAUfOHNIA
NEWYCWK
Airtsewy Energy
Honey La** Psww
Siena Pacifc tad.
HuWwi Sand * Qiaml
Aufeeifry, CA
iml J* *
TV®rKMR, bn
Haytork. CA
f» , .,,1^, n„m (|V
wyinoiv, pit
SgVaHey lumber Co,
Hwton Lumbar
Sena Paoftc Ifid.
Diamond Energy
8*»r.CA
Andetson, CA
LoyaJajn, CA
LyonacWe. NY
Sue Diamond Growers
tmptrW Resource
*** — f*»I,. iiTfTr- *--*
own riwWi tno.
KESChaieaugay
Cogwi Plant
Recovery Project
QuiiKy.CA
Chataaugay, NY
Sacramento, CA
B Centra, CA
»
Siena Paeifc: Ind.
NOflTH CAROLINA
Burney Mountain
Koppers Industries
SuMiwMt, CA
Pewer
Otwile, CA
Craven County
Sumey, CA
— - -.j f* II iniWIMM il f* Ml tin i'tfl il
signal cneryy sjyswiui
Wood Energy
Uncoln Cogeneration
Anderson, CA
New Bern, N.C.
ChowcMa Bioms*
(Jncefet, CA
Powsr Plaint I
SMedad £ner«f
VERMONT
vfwBvnH vA
Louisiana PaeMe •
SoMa&CA
Butlington Electric
Samoa, CA
Chpwehia Bwmass
Susamrtie Foksi Prod,
McHmA satoa
Ptsww Plant II
Madera Power nam
S«*wile»CA
BurtingBn. ¥T
Chowehia, CA
|CAPCO)
Ryegait Enetyy
Madera. CA
I racy riaiot
ColmPHW
T«ey. CA
Emfimm, vt
Company Project
M&fieH OcKj#f»fi&Bon
CN»*f, CA
ManaO. CA.
Ulrapower/Bbe UN«
f*A
VlftGIWA
Clomac Mecca Project
Mandktti Siomass
teHOoh
Chesapeake Ccxp,
(under oonstr.)
Pwwrtal
Ulrapower
Westpotnt, VA
Mecca. CA
Mendota, CA
Chines* Camp, CA
SWrw OwKairtar Corp.
Oetuw Energy Co.,
*A UsMfi Power
Ulffipow®f/Pn&$jfx3 »
ftOfSQWM, WA
inc.
Weetwood. CA
Maiagt. Ck
DuU.to.CA
Westvaoo
tfnrth. 'CWtr
Nonp rOfw cftBffjy
U!« tf^wm/nOQwi
Covrigisn, VA
Dinutn Energy, Inc.
North FeA, CA '
Rodtfta,CA
Dimut»,CA
WASHINGTON
Paeifc timber Co.
Wood and Siontass
El MkJo Somas#
Scoca. CA
Power Ud.
WjeSnHTigiSfl' lYlBr r*OWCr
Power Plant
Wood and. CA
Co.
0 Nido. CA
PaaSc Oiwfc Power
KettJa Falls. WA
Orovtle.CA
Fairtaven, Power Co.
CONNtSlCUT
WISCONSIN
Emtio, CA,
Redding Power Mmafva.
R«dd"mg, CA
imn ii ¦.mi nni aJfi ¦ iiiin ih Mibiiii ' ^1
wo cuf?#fiBy perna wsq
Northern Slates Power
Fantiaven Power Co.
independent wood-fired
Co.
Eunrto, CA
Sterni Pacifica tnd.
power plants
Ea-j Ojuns.WI
Bumey. CA.
Ffcfltboarf Corp.
Northern Slates Po«rer
Standard, CA
Co.
Ashland. Wl
Georgia Pacific Corp.
Pert Bran. C.A
NEW BRUNSWICK. CANADA
frederiaan, N.8.
PAGiLltliS ^yyi'Hfcp QQ m rite
PEBMmiNG PROCESS (c)
Bfe-Gen Systems
Tonington, CT '
ARSKHng*
Kilingty. CT
Uniroyai
Maupaiudt, CT ,
£.4|i|a
APduiwc ciWjjy
%snmts, tne.
GedtJes. MY
Atlantic Entity
System*. Inc.
Rome. NY
Diamond Energy
' ' , NY
Sussex, N.0.
Enerfcre
tJ> ^ ^ £ .J. |J Ft
Pl.Ok
NOTES TO TABLE 6-8
(a) W# table onfy includes major wood>6rad pemv plans and eoftneratwo baKBts that uaiiM proewsed waste wood, mri rusrtie. and agncuKuraf
residue « adthton so harveswd wood H don not include numerous smal-and mtctat-sasd mdustrtai facilities that bum primarily mil residue
(obtainet) on-soe) and hatvwted wood.
(b) All facilities on rwt list a re koown » bum at least "dew* wast® wood Some also bum varying amounts of processed waste wood containing treated
wood.
(c) These facilities are in trie planning antfor permuting process. Similar to operating facilities, the -merest by proposed laoliMs B fuel con taking treated
wood vanes by Dm types of facility, perms standards, and available fuel resource*.
6-29
I
-------
6.7.2 Underfeed Stoker Combustion System
This facility is permitted as a stationary combustion unit. It
produces 3.2 MW of gross power and slightly less than 3 MW net. The balance
is used on-site. The furnace design is an underfeed fixed grate type with a
combination ("hybrid") watertube and firetube boiler system. Each boiler is
rated at 39 MMBtu/hr and 30,000 lbs/hour steam. Current total steaming
capacity is 45,000 Ibs./far at 580"F superheated. The furnace temperature is
typically 1,800°F with stack gas exit: temperatures of approximately 300°F.
Approximately 80 percent of the waste wood fuel is from dry, mixed urban wood
sources. The wood has an estimated average moisture content of 10 to 15
percent. The remaining 20 percent of waste wood is green solid wood received
from landscaping, landclearing, and residential yard wastes.
This facility has an extensive fuel -processing system adjacent to the
combustion facility. The facility operates both as a disposal site for waste
wood haulers and as an independent power producer. The facility is permitted
as a solid waste management facility for the wood processing line; the
combustion unit is'permitted as a small stationary source under air quality
rules. The solid waste permit is necessary since the facility receives mixed
sources of construction and demolition debris, and wood waste from 30 to 40
regional haulers. The advantage of the processing line is that this facility
has a high level of control over fuel preparation.
The processing system is capable of producing 15 to 20 tons per hour and
consists of two main processing lines. All material starts oil a four foot
wide conveyor belt that leads to a 3/4-inch mesh shaker screen. From the
shaker screen, oversize material larger than six inches is sent to a
processing line that starts at a bi-level picking table. Undersize material
is sent to another processing line that begins with a trommel screen.
The picking table consists of two stations. The first and upper level uses
four people that sort for painted material, rock, rubble, metal, and other
non-wood debris. The second lower level is operated by two people and
provides an additional level of sorting for non-wood material sorting. Prom
the picking station, wood moves up an inclined conveyor and drops into a 200
horsepower hammermill shredder. From the hammermill, wood is carried up an
inclined conveyor that has a magnetic head pulley at the end. The magnet
screens ferrous metal before the wood drops onto a disk screen. From the disk
screen, oversized wood greater than three inches is conveyed to the trommel
screen, while smaller material is conveyed to the fuel pile.
The trommel screen has 1/4-inch mesh for separating dirt and wood fines. This
material is blended with fly ash, composted, and sold as potting soil.
Oversized material from the trommel screen travels up an inclined conveyor
that has a magnetic head pulley and then onto a disc screen with 5/8-inch
separation. Undersize material from the disk screen goes directly to the fuel
pile. Oversized material drops into a smaller 100 horsepower hammermill for
final sizing, before being added to the fuel pile.
A front-end loader starts the fuel delivery line by loading wood onto a
slow-moving walking floor conveyor. Whereas the processing lines and fuel
pil e are outside and open to weather, the walking floor and the rest of the
combustion system is enclosed. The walking floor meters fuel onto Conveyor #1
which has another magnetic head pulley at the end. Wood material passes
through one more disk screen to catch any pieces of long wood scraps, brick,
or non-ferrous metal missed at earlier processing stages. After the disk
screen, wood material is loaded onto Conveyor #2 which in turn feeds a
two-foot wide horizontal auger screw.
6-30
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The auger passes over two fuel hopper bins at a fuel feed rate of roughly four
to six tons per hour. Each bin, however, holds only 500 pounds of fuel. When
the first bin is topped off, fuel is automatically carried by the auger to the
second bin. If both bins are full, then excess fuel is place on a conveyor to
be returned to Conveyor #1, The fuel bins are negatively inclined to prevent
bridging. Each bin feeds an eight-inch metering screw which in turn feeds two
underfeed stoker screws for each boiler. There have been problems with wear
on the fuel augers from fine dirt and sand residue. However, the facility has
made several adjustments considered to be proprietary to compensate for this
problem.
A unique aspect of this facility is the high proportion of processed wood
used. Plant operators frequently spray water on the fuel, especially on drier
wood in the summer, as it approaches the stoker screws. Wetting fuel
increases the moisture content slightly and cools the furnace temperature.
This is done to prevent flashing and clinker formation in the bottom ash.
Although the current flame temperature is around 1,800°F, plant operators
would like to lower the temperature to around 1500 to 1600°F.
Bottom ash and clinkers are raked off the fixed grate after they build up to
approximately four to five inches on the bed. Depending on the dirt content
of the fuel, the bed may need to be raked once a day or as much as three times
a day. The bottom ash is then sent to a nearby concrete crushing facility to
be recycled as road base material. Overall fly and bottom ash production is
four to six cubic yards per day.
There have been some problems with undue expansion of the waterwalls in the
superheater and performance of the stack gas economizers. It is unclear
whether these problems are attributed to system design or system operation.
However, plant operators believe the problems are not affected by the type of
fuel burned. As a result, the boilers run at about 60 percent capacity and
overal1 thermal efficiency is lower than the designed plant capacity.
Pollution control systems consist of a multicyclone particulate
separator. The facility does not" use, nor is it required to use, any
in-furnace combustion controls. The facility plans to install an
electrostatic precipitator within the next two years.
Overall, plant operators are confident of their ability to burn fuel from
mixed urban wood sources, provided that it is properly prepared for
combustion.
6.8 Bibliography - chapter 6
Boubel, Richard w.
U.S. Environmental Protection Agency. EPA340/1-77-026 (PB278-483). 1977.
Bushnell, Dwight J., Charles Haluzok, and Abbas Dadkhah-Nikoo. Biomass Fuel
Characterization: Testing And Evaluating The Combustion Charater.isties Of
Selected Biomass Fuels. Department of Mechanical Engineering. Oregon State
University. Corvallis, OR. September 20, 19 59.
Buss, Mike, Air Quality Engineer. Kern County Air Pollution Control
District, Bakersfield, CA, Personal Communications. April 10, 1991 and
January 22, 1992.
Campbell, Alton G. SmaH-l8_iaBfliuBi Sized Modular Combustion Systems.
University of Idaho. Moscow, ID, For the Biomass Energy Project Development
Guidebook. U.S. Department of Energy, Bonneville Power Administration.
Portland, OR. June 1389.
6-31
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Desahye, Joyce A. and James D. Kerstetter, PhD. 1990 Washington State
Directory, of Biomass Energy Facilities. Washington State Energy Office.
Olympia, WA. 1990.
Fitzgerald, Bruce. Kenetech Energy Systems, Inc. Meriden, CT. Personal
Communication. November 14, 1991..'
Fresno County Air Pollution Control District. Permit to Operate.
Ultrapower-Malaga. Malaga, CA. August 1989,
Getz, Ray. Air Quality Engineer. Virginia Department of Air Pollution
Control. Roanoke. VA. Personal Communication. April 16, 1991.
Great Lakes Regional Bioiaaas Energy Program. Industrial/Commercial Wood
Energy Conversion. Madison, WI. 1986.
Grey, torn. President. Midwest Pacific Resource Corporation. Norman, OK,
Personal Communication. January 10, 19 92.
Grimm, Phil. Industrial Wood Energy; A Guide For Virginia. Virginia Division
of Forestry. Charlottesville, VA. 1985.
Hanson, J. Levi, P.E. Fluidized. BedCombustion Of Biomass: An Overview. JWP
Energy Products. Coeur d'Alene, ID. January 1992.
Hacker, Christopher. "The Nuts and Bolts of Plant Upkeep." Solid Waste.and
Power. Kansas City, MO. April 1991.
J.P.R. Associates. Guidebook Par...Industrial/Commercial Wood Energy
Conversion. Stowe, VT. April 1984.
Joseph, William, Environmental Co-ordinator. • Wheelabrator Shasta Energy Co.
Anderson, CA. Personal Communications. June 11, and July 16, 1991.
Kaylor, Gregg. The Tischer Group. Fresno, CA. Personal Communication. June
19, 1991.
Kenedy, Mark. Manager. Hubbard Sand and Gravel. Bayahore, NY. Personal
Communications. June 11, 1991 and February 20, 1992.
Kern County Air Pollution Control District. Authority to Construct. Delano
Biomass Energy Company. Delano, CA. March 1991.
Kerstetter, James D. , Ph.D. Assesament Of Bi omasa. Resources._.For Electrie
Generation In The Pacific ..Northwest. Washington State Energy Office.
Olympia, WA. 1990.
Kirkland, Larry. "Contracting For Biomass Fuels". University of Idaho.
Moscow, ID. For the Biomass Energy ..Project Development Guidebook. U.S.
Department of Energy, Bonneville Power Administration. Portland, OR. August
15, 1991.
Knight, Jim. Air Quality Planning, Department of Environment. Province of
New Brunswick, Canada. Personal Communication. February 14, 1992.
Langr, Kenneth. A Comparison Of Wood. Coal. And RDF Combustion Systems -
Focus On N.S.P. Bav Front And French Island. Northern States Power Company.
Eau Claire, WI. January 1992.
6-32
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Leone, Catherine. Special Projects Engineer. Tacoma Public Utilities, Light
Division. Tacoma, WA. Personal Communication. October 1, 1991.
Miles, Thomas R. and Thomas R. Miles, Jr. 'Urban Wood: Fuel Prom Landscapes
and Landfills." Biologue. Washington, DC. September 1991.
Miles, T.R. and T.R. Miles, Jr. "Bioroass Fuel Handling and Feeding
Properties, presented at Biomass Combustion Conference, Western Regional
Bioroass Energy Program", January, 1992.
Murphy, Keshava S., D. Bruce Henshel and Herman Hack, "Environmental
Assessment of the Fluidized-Bed Combustion of Coal ~ Methodology and Initial
Results.
Association. Toronto, Ontario, Canada. June 1977. Paper no.77-26-6.
New York state Department of Environmental Conservation. The Division of
Solid Waste Technical and Administration Guidance Memorandum. "Regulatory
Requirements for Wood Chips, Wood chipping Operations and Wood-Fired Energy
Recovery Facilities". Albany, NY. July 25, 1991.
Rader, Nancy. Air Quality Impacts of Blomass-Fueled Electric Plants.
Graduate student, Department of Engineering. University of California.
Berkeley, CA. December 5, 1991.
Randolph, John. Virginia Energy Pattern and Trends. Virginia Department of
Mines, Minerals, and Energy* Richmond, VA. 1991.
Schroeder, Mary. Fuel Procurement Manager. Wheelabrator Shasta Energy
Company. Anderson, CA. Personal Communication. June 18, 1991.
Schultz, Sheldon. Experience Burning Wood Waste In Fluidized Bed Boilers.
Yanke Energy. Boise, ID. January 13, 1992.
Simbeck, Dale and Donald Wilhelm. Outlook Of Fluidized Bed Combustion For The
1990's. SFA Pacific, Inc. Mountain View, CA. Presented at The Council of
Industrial Boiler Owners {CIBO} Fifth Annual FBC Conference. December 11-12,
1989 .
Southeastern Regional Biomass Energy Program. Directory Of Biomass
Installations in 13 Southeastern States. Muscle Shoals, AL. December 1986.
Terry, Lynn M. Manager, Energy Projects Section. California Air Resources
Board. Sacramento, CA. Personal Conrounications. July 18, 1991, and February
5, 1992.
Tillman, David A. The CambasJlioiLj^^ Ibasco
Environmental. Bellevue, WA. Academic Press. 19 91.
Turin ay, John. Facilities Manager. Ajax Energy Corporation. Bampton,
Ontario, Canada. Personal Communication.
Vranizan, John M., Peter Neild, Linda S. Craig, and Robert L. Gay. Biomass
Energy Project Development Guidebook. DOE/BP-61195-1. Pacific Northwest and
Alaska Regional Biomass Energy Program. U.S. Department of Energy, Bonneville
Power Administration. Portland, OR. July 1987.
Wilhelm, Donald J. and Dale Simbeck. The California FBC Boiler Story. A
Status Report. SFA Pacific, Inc. Mountain View, CA. Presented at The
Council of Industrial Boiler Owners {CIBO} Sixth Annual FBC Conference.
December 9-11, 1990.
6-33
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Wisconsin Energy Bureau. Directory of Wisconsin Wood Burning Facilities.
Department of Administration, Madison, WI. August 1990.
Yandle, Margot E. and Eric Loi. Database and Regulatory Options for Wood
Fired Systems Draft Pinal Report. Environment Canada. Toronto, Canada.
September 1990.
Yankee Energy. "Summary of Project Work". Boise, ID. 1991
Ziegler, Urban. Combuston Engineer. KMW Energy Systems Inc. London,
Ontario, Canada, Personal Communication. July 2, 1991,
6-34
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7.0 CHEMICAL AND PHYSICAL PROPERTIES OP WASTE WOODS AND THEIR
ASHES
7.1 Introduction
This chapter describes the chemical and physical properties of waste woods arid
the ash produced from the combustion of these materials. The purpose of this
chapter is to quantify the properties of waste wood materials. To date there
has been very little information on the chemical and physical properties of
waste woods in the technical literature. There has been some information on
"clean" wood but it is also extremely limited and is not completely applicable
to waste wood combustion. Since there is increased interest in using waste
wood for the production of energy it has become extremely important to
understand its properties and to be able to predict the environmental impact
from its burning. The type of information gathered in this study is needed to
evaluate the emission of trace metals from the combustion of waste wood and to
understand the metal contaminants in the ash. Table 7-1 is a summary of wood
and ash analyses performed for this study. The waste wood data collected and
reported here can be used by developers, regulators and other interested
parties:
• In evaluating combustion and pollution control alternatives;
• In predicting air pollution emissions and ash properties front
the combustion of waste woods and;
• In evaluating the environmental impacts due to the combustion,
of waste woods.
This study used random sampling techniques to obtain waste wood and ash
samples from six waste wood processing and two combustion facilities located
in the United States and Canada that employ various processing and combustion
approaches. These samples were then ground to a fine size, blended and
analyzed to obtain information about their chemical and physical properties.
Ash samples were obtained from combustion facilities and by laboratory ashing
of the collected waste wood samples. This chapter and its associated
Appendices discusses:
• How the waste wood and ash samples were collected.
• The types of analyses performed.
• The analytical results and their variance and ranges.
• The statistical significance of the analytical data.
• Recommended values for development studies.
• Recommendations on how to limit variability of waste wood
properties.
• Recommendations for future data collection,
• The data collected are further evaluated in Chapter 8 to
assess their environmental impact and to predict whether waste
wood can be properly combusted and still meet environmental
regulatory standards,
7-1
-------
The waste wood samples were collected from various types of wood processing
facilities. By reviewing the descriptions of the processors and evaluating
the data collected at each individual facility the reader can draw some
Table 7-1, Wood and Ash Analyses,
ABBREVIATED NAME
Ultimate/Proximate (w/Cl)
Determination of total water, ash,
Btu, volatile, fixed carbon, sulfur,
total carbon, H, N, 0, CI
Alkalies as NaO
Total Elemental Metals (drvl
Include As, Ba, Cd, Cr,
Pb, Ni, Kg, Zn, Cu, Ti
Total Elemental Metals For
Five Metals (drvl
Include As., Pb, Zn, Ti, Cr
TCLP (Metals and Oraanics)
Analysis includes ZEE and rotary
extraction
Ult/Prox
Total Met
5 Met
TCLP Total
TCLP {Metals Only)
Phenols (Method S270 or 8040)
Phenols and chlorophenols
TCLP Met
Phenols
Includes oxides of Si, A1,
Ti, Fe, Ca, Mg, K, Na, S, P
Pb, Zn
TCLP {Metals and Oraanics)
TCLP (Metals Only)
Total Elemental Metals
Same metals as for wood
Min Anal
TCLP Total
TCLP Met
Ash Metals
conclusion based upon the types of waste woods processed and the processing
methods used. This information will be helpful in designing future waste wood
processing systems and in understanding the quality of waste wood fuel which
could be produced.
Homogeneous waste wood samples were also collected and analyzed in this study.
Some of these samples were collected from facilities burning these homogeneous
7-2
-------
materials. In those instances, ash samples were also collected and studied.
The following types of homogeneous waste woods were collected and analyzed:
• plywood;
• CCA pressure-treated wood;
• particle board;
• creosote-treated wood;
• furniture scraps; and
• laminated woods.
This chapter defines the scope of the testing program, identifies the types of
waste wood that were tested from sources characterized in Chapters 5 and 6,
describes the methods used to obtain and analyze samples, and provides a
statistical summary of the results. This chapter is organized into the
following sections.
• Section 7.2 describes the development of a sampling plan and
the statistical treatment of the data.
• Section 7.3 provides an overview of the sampling and analysis
plan, specifying the sample sizes and sources of each sample
unit.
» Section 7.4 is a detailed description of the sampling
methodology used to obtain the wood and. ash samples.
• Section 7.5 describes the analytical methods used by the
laboratories to determine the wood and ash characteristics.
• Section 7.6 presents the sampling results and the conclusions
that can be drawn, from them, this section also details the
concerns about the variability of the data, test repeatability,
and differences in analytical methods.
7.1.1 ley Issues
• What are the major contaminants in waste woods and homogeneous
waste wood types?
• What is the variability in the level of contaminants?
• What is a maximum level of contamination?
• What is a realistic contamination level to use for permitting
facilities and evaluating environmental concerns?
7.1.2 Key Findings
• Data on. energy values, chemical and minerals analyses and
concentration of metal contaminants in "clean" and "treated"
wood and its ashes.
• Data on energy values, chemical and minerals analyses and
concentration of metal contaminants in homogeneous wood types
and their ashes.
7-3
-------
• The variability of the preceding physical and chemical
parameters within the waste wood fuel stream at each specific
test site and among the various sites tested. These parameters
and their variability are important factors in the design of
waste wood processors and combustion facilities.
• Suggested values of these physical and chemical parameters to
be used in estimating a waste wood combustion system's
environmental emissions.
7.2 Statistical Sampling Technique*
A major objective of the project was to estimate various chemical and physical
properties of processed and homogeneous waste woods and to establish their
•variance and mean, within a prescribed level of precision. These waste wood
properties were to be estimated from operating facilities throughout the
United States and Canada. Therefore, the various analytical data obtained
during this study was reviewed to determine:
• maximum and minimum levels;
• mean, median and log normal mean values; and
• confidence levels.
The aim of the study was to determine chemical and physical parameters and to
use that data to establish guidelines for predicting fuel parameters from;
• any waste wood processing facility without regard to the type
of waste wood received and the processing methods employed, and
• waste processors preparing a higher quality wood fuel due to
qua!ity control of the wood received at the facility or to the
types of processing used to remove contaminated wood streams.
toother major goal was to determine the variance of wood and ash properties
among and within individual facilities to assess the effect, of site-specific
factors on product quality by treating each facility as a distinct
"population* and applying a uniform statistical sampling method. Sufficient
samples were collected to estimate confidence levels of the analyzed
properties,
Waste wood is a bulk material, compared to a group of unique, discrete units.
Therefore, the physical methods and statistical aspects of bulk materials
sampling were used (Bicking, 1967), {Duncan, 1974), (Schilling, 1982). The
wood and ash is classified as "Type A" materials, a term referring to bulk
material on a conveyor or pile which is not composed of distinguishable
segments. For sampling of Type A bulk material, sample units must be created.
{"Type B" bulk materials are segmented into primary sample units, such as bags
or boxes).
Several specific terms used throughout this chapter are defined as follows;
• Lot: The mass of bulk material under study. In this study,
the entire stockpile of a processor or combustor, plus the
production during the sampling day is the lot. Stockpile
storage capacities are usually several days.
• Segment. and Primary Sample Unit: A segment is any
specifically demarked portion of the lot, actual or
7-4
-------
hypothetical. Segment size depends on the process and
material. For this project, a segment is considered, to be
nominally equal to the volume of one half to two truckloads at
a processing facility. The primary sample unit is a sample of a
segment, Primary sample units were analyzed to determine
variance within the lot {variance between segments).
• increment, or Secondary Sample Unit; Those portions of the lot
initially taken, into the sample. In this study, increments
were drawn from segments and composited into primary sample
units. Increments were also analyzed separately to estimate
variance within segments and provide additional data points for
statistical averaging.
• Reduction; The process by which a sample is split for
subsequent analysis. Increments were reduced so that a portion
was analyzed individually and another was composited with other
increments into a primary sample unit. Some analyzed portions
of increments were reduced for duplicate analyses. Primary
sample units and composites of primary sample units were
reduced for laboratory analysis.
• Sample. vs. Sample ..Unit: A sample is comprised of individual
sample units, each of which are analyzed for a particular
characteristic. Sample size refers to the number of sample
units available for a characteristic at each site.
A schematic representation of these terms, as they apply to the current
project, is provided in Figure 7-1.
Since it was physically impossible to sample the wood stock piles at different
depths no special stratified sampling techniques were used. It is probable,
however, that the stockpiles are not homogeneous; different segments, and
different increments, probably have varying characteristics due to variations
in the quality of wastes from which the processed material is derived. Most
processors do not deliberately mix up wood fuel in the stockpile, but rather
form piles sequentially so that wood from a series of at least two or three
waste trucks forms one pile. The sampling plan for stockpile sampling was
designed to Identify heterogeneity. In addition, production samples from the
line were taken to identify the characteristics of the wood produced during a
typical sampling day.
7,2.1 Statistical Sampling Methods
Careful attention was given to the sampling methods used to insure the
validity of the data. Great care was taken to develop a plan that revolved
around bulk materials sampling. A bulk sampling process consists of the
following steps (Bicking, 1967):
1. Collection of a relatively large amount of material in a systematic
manner from the lot;
2. Selection from this large amount by subdividing {e.g., quartering!
enough material of the same average composition for the required
analytical test; and
3. Crushing, grinding and mixing the collected material (if necessary} for
subsequent analysis.
7-5
-------
Processor
Stockpile
Lot
-------
The concept of random sample selection is critical in this sampling plan. At
each incremental sampling location a relatively large sample was collected
compared to the amount necessary for analysis. Rather than taking a grab
sample from this increment and, thus, possibly biasing subsequent tests,
samples were reduced by a method known as "quartering." This is described in
greater detail later in Appendix P, but generally consists of taking the
available material and dividing it into four equal parts. Two opposite parts
are then combined, thoroughly mixed, and quartered again. This process is
continued by dividing samples in half in a random fashion until the proper
amount necessary for analysis remains. The bulk of the material sampled in
this project consisted of; hogged or shredded wood chips of two to four inches
nominal size. To prevent any analysis from representing only one or two
pieces of wood, quartering was halted when the sample was reduced to one
gallon of material which was then milled into quarter-inch splinters or
smaller particle size before being reduced further for analysis.
7.2,2 Statistical Concepts
To understand the significance of the data from this project, it is necessary
to understand the basic difference between normal and skewed data
distribution. A normal distribution, or "bell curve," is defined by the mean
and standard deviation of a data set. The mean in this case, is an arithmetic,
average of the data collected. The normal distribution, as shown in Figure
7-2, is a curve symmetrical about the mean. For every number of samples that
fall a certain distance below the mean an equal number of samples should
register that distance above the mean. In an ideal normal distribution the
arithmetic mean and the median of the data fall on the same value. The median
is the point where 50 percent of the data points fail to either side. Another
property of the normal distribution is that 68 percent of all data are within
±1 standard deviation from the mean and that 95 percent of all the data fall
within £2 standard deviations. It is possible, if a sample data set follows a
normal distribution, to calculate confidence intervals about the mean. A
confidence interval for the mean is a range of- values in which it is believed
the true mean, of the population lies. Thus, if a 95 percent confidence
interval is determined, then the mean of any similar random sample, from the
sample population would have a value within that range 95 percent of the time.
This can also be said of the median.
When dealing with environmental concerns, emphasis must also be placed on
knowing the "maximum average" value rather than the average or minimum value.
Therefore in this project it was more appropriate to determine the upper
confidence interval. This upper bound value was determined, within a fixed
confidence level of the calculated mean.
Unfortunately, for heterogeneous fuels a lognormal distribution of their
properties is.more commonly seen than a normal distribution. Lognormal
distributions are skewed to the left with some outlying data points producing
a diminishing tail to the right (Figure 7-2) because different contaminant
concentrations are associated with different waste wood fractions {see Section
7-4). therefore, a variation in the concentrations of different waste wood
streams will produce widely differing contaminant levels. In a lognormal
population, the arithmetic mean {sum of the values divided by the number of
values) can not be used to estimate the population's true average unless the
number of samples taken is very large. A better estimate of the true mean is
the median of the data. As before, with normal distributions, confidence
intervals can be calculated for lognormally distributed data sets. The median
of a lognormal distribution may be estimated by the geometric mean.
Therefore, in evaluating emissions from wood burning facilities the geometric
mean of the various contaminants should more closely represent true average
operating conditions.
7-7
-------
Variable NORMAL ; distribution: Normal
*8 —i—r""1 i" ":i ""rjl ¦ ¦"« » > i '»» < • - r
Ctl«for« (ww I
Variabto LOG NORM ; tfetrtowtiw; Lognormal
Expected
m f» Ot fv *r
•u ftj « a n
C«>«*arv (u«mmv- tiaiT«>
Figure 7-2. Normal vs. Lognormal Distributions.
7-8
-------
In this study it was determined that the bulk properties of wood such as
ultimate and proximate, BTU value carbon, hydrogen, oxygen analysis followed a
normal distribution, whereas the properties associated with contaminants such
as metals, chlorine, sulfur, ash and moisture followed a lognormal
distribution,
7,2.3 Compositing of Samples
The more samples of a population, the greater the accuracy of any resulting
statistical calculations,* however, it is not always possible or cost effective
to analyze many samples especially when dealing with a very large population.
This problem is further compounded when very small sample quantities are
analyzed and small' particles of contaminant can result in large analytical
differences. To alleviate the cost of analyzing every sample taken while
still generating reasonable results, it was appropriate to composite samples
before analysis.
In the procedures established for gathering samples, the lot or population of
each facility was divided into eight segments. From each of these segments,
five or more incremental samples were taken. In the case of certain metal
contaminants (As, Cr, Pb, Ti, and Zn) the increment samples were analyzed
individually. Other increment samples were randomly reduced in size and
combined with additional increments from the same segment. This new sample
was used to estimate the average characteristics of that segment. A
comparison of incremental samples and their composites, for the same metals,
indicated that the compositing procedure more accurately predicted fuel
properties. As discussed later in this chapter, the data confirms that when
additional samples are taken from a population, the resulting distribution of
the data more closely fits a normal distribution. The composite samples
exhibited more of a normal distribution than their corresponding increments
and were more representative of their true value and of the facilities' design
parameters.
7.3 General Sampling and Analysis Plan
7.3,1 Homogeneous Wood Types
Six homogeneous wood product categories were sampled and analyzed to determine
the physical and chemical characteristics of common wood products.
At least one sample from each category was analyzed for ultimate/proximate,
chemical composition, minerals, total metals and phenols. In cases where
actual furnace ash was available it was analyzed.
1. Plywood - Scraps from a manufacturer of plywood were received along with
an ash sample from the manufacturer's combustor. An approximate five-
pound sample of wood was ground and analyzed.
2. Pressure-treated Lumber - Two samples of clean, unweathered
pressure-treated wood and a sample of fire-treated/pressure- treated
wood were ground and analyzed. A TCLP test was run on one sample of
each type of treated wood.
3. Particle Board - Four samples of particle board were ground and
analyzed. Each sample consisted of approximately five pounds of clean
cut boards. One was a sample of southern hardwoods; the others were
samples of southern pine.
7-9
-------
4. Creosote Treated - Samples of used railroad ties and telephone poles
were collected and analyzed separately. Ten railroad ties from 30 to 50
years old were sampled. The condition of the ties varied from rotting
to no structural disintegration. From 10 to 15 telephones were hogged
for this project. Approximately 100 pounds of chips were collected and
quartered into a ten-pound sample for analysis. A complete TCLP was
performed on the ground wood to determine the effects of creosote-
treated woods on landfills,
5. Furniture Manufacturer Scrap - Two different samples of scrap generated
during the manufacture of furniture were analyzed. The first sample
consisted of birch wood sheets glued together to form a solid wood core.
The second consisted of sawdust from a combination of hardwoods,
laminated woods, and wood composites. An ash sample from the facility
burning these materials was also analyzed,
6. Laminated Wood Panel Products - Small samples of wood and ash were
received from a plant burning laminated woods. There was not enough
material to run all of the analyses. An ultimate/proximate analysis and
a total metals analysis were performed on the wood while minerals
analysis and a total metals analysis were performed on the ash.
7.3.2 Waste Wood Processors
Six waste wood processors were sampled as part of the project. Random
stockpile samples indicative of normal processing activities were taken from
each facility. Also from three of the facilities, samples were taken from
conveyors to obtain information on wood produced during the sampling day. The
samples were taken using bulk material sampling methods previously discussed.
The analyses performed on each supple collected is described in Figure 7-3
which outlines the stock pile and conveyor sampling methods. When conveyor
sampling was net possible, additional samples were taken from the stockpiles.
Fox* the analyses that, required ash samples, slight variations to the sampling
method had to be made. Since wood is 2 percent to 10 percent, ash, a much
larger sample of wood had to be collected to generate appropriate quantities
of ash for analysis. it proved more feasible to collect these samples from a
combination of several segments instead of one larger segment, a modification
discussed in Section 7-3.
When possible a total of eight primary sampling segments were obtained from
each processor, six from the stockpiles and two from the conveyors. Each
primary unit is a composite of increments from one segment. For stockpile
samples, a segment is defined as the volume of wood e
-------
Wood stockpile sampling,
Conveyor sampling
Increments (5
per segment)
5 metals
Segment 1 |
Segment 2 Segment 3
Segment 4
Segment 5
Segment®
rrrmiTniinTTrinTmrTTTTimTr
Combine
Combine
Segment 5
Segment 6
increment
increment
\T\1\
metals
~
otal
metals
1 I
MWWDIn©
G©fvitin@
s®0it@rts
t and2
3and4
Split
sample
Phenol
a
ULT/PROX
~
ULT/PROX
~
Sample to be
reduced to ash
nr
Mineral TCLP (met)
Increments (5
per segment)
Sample to be
reduced to ash
TCLP (met)
Figure 7-3, Wood stockpile sampling/conveyor sampling.
-------
• Arsenic can be used to indicate the presence of
pressure-treated wood, which is commonly impregnated with
arsenical water-soluble preservatives.
Arsenic is also an indicator of biocides and herbicides used in
wood treatments.
• Chromium is a prime component of water-soluble preservatives
and yellow paints.
• Lead is art indicator of lead-based paint.
• Titanium is a primary component of modern paint and usually is
not present in any other waste wood treatment contami nant.
• Zinc is a prime component of fire-retardation treatments and of
white paints.
A total elemental analysis for 11 metals, the "five metals" and barium,
cadmium, copper, mercury, nickel, and silver were also undertaken. As seen in
Figure 7-3, the total number of primary sample units analyzed for "total
metals* is eight. Segments 1, 2, 7, and 8 had "total metals* analyses
performed on combinations of four individual increments.
As shown in Figure 7-3 four composite samples were prepared from stockpile
samples to determine ultimate/proximate and phenol values. Also, four
conveyor samples from each processor were analyzed for these parameters.
Variability between segments is lost by this method. However, the
ultimate/proximate properties were not expected to vary significantly between
segments. Therefore, the variability data for these analyses was not
critical and provided sufficient data for statistical analysis (e.g., to
estimate variance, mean, etc.) of these properties. Also, this study was to
explore whether phenol determinations could be used to characterize and
identify particular waste wood properties, Very limited data was to be
gathered to evaluate the use of the phenol analysis.
Stock pile and conveyor samples were also composited into samples to be
laboratory ashed. Ash characteristics are more important on the scale of
several "truckloads"r because the volume of ash is only about 2 to 10 percent
that of wood. In the early part of the program, attempts were made to collect
samples to be ashed from as few segments as possible. It was later determined
that combining several segments together to form composite samples better
represented the site and significantly reduced sampling time. The ash
generated from each sample was tested for its minerals content and metal
leaching toxicity (TCLP).
7.3.3 Waste Wood Combustion Facilities
Two facilities permitted to burn waste wood were willing to allow a limited
sampling program. Site 5, while permitted to burn waste wood, was not doing
so at the time of the site visit. However, waste wood emissions data from
this facility was obtained from prior test programs and is presented in
Section 8. For comparative purposes, some sampling was performed from the
feed conveyor, the bottom ash hopper, and fly ash hopper. These samples were
taken concurrently every 10 minutes for a total of eight samples.
Site 8 was burning mostly waste wood. Unfortunately the bulk of the material
burned at that site undergoes little if any size reduction and the feed
material was too large to sample. However, samples of ash were collected at
the end of each day over a seven-day period. Two types of ash were collected
7-12
-------
from this site; bottom ash consisting of material dropping off the end of the
grate, and sifting, consisting of ash that fell in between the grates. There
'was no flue gas particulate collection system so fly ash samples were not
obtained.
Figure 7-4 shows the distribution of analyses performed on both the wood and
ash samples collected. To determine sample variance, two random samples from
each half of the sampling period were analyzed for "five metals". All the
increments from each half of the sampling period were combined and analyzed
for total metals. For the ash samples, a composite of all the increments was
analyzed for minerals composition and a TCLP test. For the wood samples, a
composite of all the increments was analyzed for ultimate/proximate and
phenols analyses.
In addition to the above testing, some additional TCLP tests were run on
available ash. Often, ash is quenched at combustors before collection is
possible, but in some cases ash was collected dry. To simulate the
cementation process that combustion ash undergoes when wetted, distilled
deionized water was added to splits of some of the dry samples. These
mixtures were allowed to set until hard, ground, and tested for TCLP.
7.4 Analytical Methods
Each of the laboratory analyses performed as part of this project is described
below,
7.4.1 Ultimate/Proximate Analysis
This test is a basic analysis routinely done on all types of combustion fuel.
It determines the properties most important in the design of the combustion
system. On a moisture and ash-free basis this test is not significantly
affected by the type of waste wood and therefore, only composite samples were
analyzed.
The ultimate/proximate analysis includes the following determinations:
• Heating value (Btu/lb>
* As a percent by weight:
-Hydrogen -Ash
-Total Carbon -Oxygen (by difference)
-Fixed Carbon -Sulfur
-Nitrogen -Chlorine {not usually part of ultimate analysis)
-Volatile® -Alkalies as sodium oxide
The sulfur and chlorine content is important in terms of evaluating
environmental impacts of acid gases.
The test methods used by the laboratory were ASTM methods D3176, D3173, and
D2361.
7.4.2 Elemental Metals Analysis {"five metals* and "total metals")
This series of tests determines the concentrations (pptn by weight or ^g/g) of
each of the following elements in the sample.
7-13
-------
Start
Combustor Ash/Wood
Middle
End
Time Period
OOOOiOOOO »~ «=
i i i i ; i i i i
Break up samples and sif| (4mm Mesh), if necessary
sampled at
Quarter two random samples from each half of time
period and analyze for five metals (4 total)
Quarter and mix {by weight) increments into 2 sample units
1 I. 1 I L _J I I
Analyze for
total metals
Analyze for
total metals
Combine sample units and run TCLP
test and a mineral analysis
Figure 7-4' Distribution of analyses performed on wood and ash samples,
-------
Arsenic®
Barium
Cadmium
Chromium*
Copper
Lead*
EPA Method8
7060
7081
7131
7191
7211
7421
Element
Mercury
Nickel
Silver
Titanium®
Zinc*
a "five metals* analysis
b see Teat..Methods, ,, in Bibliography Section
c see fPf in Bibliography Section
Analysis by the above methods entails digesting the sample {wood or ash) in
concentrated acid (HN03) (EPA 3050) and then testing for each element in a
graphite furnace using atomic absorption. The method usually requires only
one gram of analyte to be digested. Even after blending and grinding, it was
believed that this was too small an amount to test considering the
heterogeneous mixtures of wood tested. Thus, the testing laboratories were
requested to digest five grams of sample per test to increase data
reliability. The composite samples for site 7 were tested at a different
laboratory using different test methods to compare the effectiveness of test
methods.
Each sample was prepared (ASTM D3683) analyzed for trace elements {barium,
silver) by inductively coupled plasma emission spectroscopy. Arsenic was
determined by graphite furnace atomic absorption. Mercury was determined by
double gold amalgamation cold vapor atomic absorption. Titanium was
determined by fusing with lithium tetraborate (ASTM D3682I, cadmium, chromium,
copper, lead, nickel and zinc were determined by aqua regia digestion of ash,
followed by atomic absorption analysis.
7.4,2.1 Titanium Analysis
Titanium concentrations in the samples were determined by two methods. Most
of the total metals and all the "five metals* analyses used EPA methods {EPA
3050, EPA 283.2}, In general these methods involve the acid digestion of the
sample into solution and then analyzing the extracted fluid. A second method
{ASTM D 3682} was used to determine titanium concentrations for the minerals
analysis. This method was also used for the site 7 total metal analyses.
This method, which determines the major components of ash, involves fusing the
ash with lithium tetraborate,- digesting this fused material in hydrochloric
acid, then analyzing the resulting fluid. The minerals analysis, by fusing
ash with this other compound, ensures a complete digestion of the material.
Based on a review of the data it appears that the first method may not have
ensured a complete digestion. Conversations with the laboratory performing
the work using this method indicated there was an insoluble white residue left
in the digestion chamber.
Titanium in its elemental form is soluble in dilute acid; however, several
titanium compounds such as titanium dioxide are insoluble in acids and/or
somewhat soluble in sulfuric acid {CRC, 1985!. Titanium dioxide, which is
used in modern paints as a binder, is white. It is suspected that the
undigested white material from the metals analysis was titanium dioxide.
The fact that the two methods do not correspond is apparent when looking at
the results for site 1. The average value of titanium by the minerals analysis
method for site 1 was about 300 ppm compared to about 50 ppnt to 100 ppm
averages of total metals and "five metals" respectively. Review of the data
from sites 2,4, 6 and the "five metals" analysis of site 7, show the same
disparity in titanium concentrations which suggests that ASTM D 3682-87 is the
7-15
-------
better method for determining titanium concentrations in the future. As a
result, the work reported in subsequent sections uses the mineral analysis
data for titanium as representative of its true value,
7,4.3 Phenols
The following list of phenol compounds were tested for in composite samples of
the wood fuel.
Phenol 2-Chlorophenol
2-Nitrophenol 2,4-Dimethylphenol
2,4-Dichlorophenol 4-Chloro-3-methylphenoI
2,4,6-Trichlorophenol 2,4-Dinitrophencl
4-Nitrophenol 2-Methy-4, 6-dinitrophenol
Pentachlorophenol
The method used to determine the parts per million by weight concentration, of
each compound was USEPA method 8270 (SW-846),
7.4.4 Laboratory Ash
In most instances it was not possible to collect waste wood and its
corresponding ash samples from the same operating facilities. None of the
wood processors burned waste wood. Those facilities burning waste wood from
processors tested were also burning other waste wood and or waste material.
Therefore, corresponding ash and waste wood samples could not be obtained.
Therefore, samples were prepared in the laboratory from the waste wood fuel to
determine the chemical characteristics of its wood ash. In the ashing method
used, the wood sample is placed in an oven at 5 50°C {1, 002CF) and allowed to
combust slowly for several hours. This method is used to minimize
volatilization of metals while still achieving complete oxidation of the
combustible material. While this method is not representative of high
temperature and turbulent combustion conditions of an actual boiler, it does
provide an ash sample with conservative concentrations of metals and other
elements. However, the oxidation level of the metal compounds and the type of
compounds found probably is not representative of actual full-scale combustion
parameters.
It is believed that ash prepared in this manner has a chemical concentration
reasonably close to the chemical concentration of ash from a wood-fired boiler
because the wood is combusted for at least one hour or longer for this method,
and it is periodically weighed until a constant mass is achieved. This
ensures that all combustible material is oxidized and all volatile material is
driven off. However, the high temperature combinations of various compounds
in the ash that could occur in boilers probably does not occur during these
preparations. For example, during actual combustion arsenic may be converted
to AsvO, while in the laboratory it could be converted to As;0^. The trioxide
form is much less soluble than the pentoxide form and therefore significant
leaching could result. Similarly for the other metals tested, different
oxidation levels and different metal salts such as chlorides, sulfates, and
sulfites could be formed, resulting in widely different leaching properties
for laboratory ash compared to actual combustion facility ash,
7.4.5 Mineral Analysis
This test determined the bulk composition of wood ash. For either ash
generated in the laboratory or received from a combustor, samples were tested
for percent metal oxides by weight of the following elements:
7-16
-------
Silicon, Aluminum, Potassium, Sodium, Titanium, Iron, Sulfur,
Phosphorus, Calcium, Magnesium, and Undetermined
When the undetermined portion of the sample was too large, further analysis
was performed. The percent by weight oxides of the following were tested for
until the undetermined portion of the sample reached a reasonable level.
Lead, Zinc, Manganese, Copper, Strontium, and Barium
This analysis was performed by ASTM Method D-3682-87. The titanium oxide
value was judged more representative of the amount of titanium in the wood
fuel than the levels determined by the evaluated analysis Method 283.2.
Therefore, this mineral analysis was used to back calculate the titanium
concentration in the waste wood streams wood. These values are also reported
in the tables that follow.
7.4.6 Toxicity Characteristic Leach&t* Procedure {TCLP)
The Environmental Protection Agency's Test Method 1311, otherwise known as the
Toxicity Characteristic Leachate Procedure (TCLP), is used to determine if
wastes are characteristically hazardous. Ash that fails the TCLP must be
disposed of properly in authorized landfills or be specially treated, the
TCLP procedure replaces the EP toxicity method. Table 7-2 lists the
constituents of concern and the regulatory level that would subject the
material to all RCRA Hazardous Waste requirements.
The TCLF test was performed on composite ash samples froro the combustion
facilities as well as laboratory-generated ash from the processors. Unburned
creosote-treated samples of railroad ties and telephone poles were also tested
to evaluate the effects for landfill disposal of this material.
Also, TCLP "wet." tests are defined as tests where dry ash samples were wetted
and dried to allow for pozzolanic reactions. It has been proposed that the
pozzolanic process fixes constituents that may otherwise leach out of the
mixture. The TCLP data should be evaluated considering the previous iy
expressed concerns about the representatives of laboratory-generated compared
to actual boiler ash. TCLP test failure of laboratory ash may not be
applicable to full scale boiler ash of the identical fuel type.
7.5 Test Results
This section presents the test results and evaluations of the testing
performed on the wood and ash samples. Tables in this section summarize the
statistical information calculated from the raw data. Tabulations of all the
analyses can be found in Appendix G. Also found in this Appendix are the
computer statistical computational outputs.
This section also discusses the confidence in the analytical methods used and
recommends procedures for future sampling and testing programs.
While reviewing this data the reader will notice two sets of titanium values.
As indicated previously, values determined as part of the "total metal* and
"five metals'* analysis are suspected to have low titanium levels. All
discussions relating to titanium concentrations are therefore based on the
results of the minerals analysis which is felt to be more accurate {see
Section 7.4.2) .
7.5.1 Homogeneous Wood Saaplea
7-17
-------
Table 7-2. Toxicity characteristic leachate procedure {as of mid-1992).
1 Constitutent
EPA
hazardous
waste {HWi
number
Minimum
detection Limit
CMDI4*
Regulatory
level
mg/1
mg/1
Volatile organics
Benzenne
D018
0.01
0.5
Carbon tetrachloride
DC19
0,01
0.5
Chloroben2ene
D021
0.01
100
Chloroform
D022
0.01
8.0
1,2-Dichloroethane
DO 2 8
0.01
0,5
1,1-Dichloroethylene
D029
0.01
0.7
Methyl ethyl ketone
D035
0.01
200
Tetrachloroethylene
D039
0.01
0.7
Trichloroethylene
D040
0.01
0.5
Vinyl chloride
D043
0.01
0.2
Se*i-volatile organic*
Acid fraction:
o-Cresol
D023
0.10
200
m-cresol
D024
0.10
200
p-cresol
D025
0.10
200
Pentachlorcphenol
D026
0.10
200
2,4, 5-Trichlorophenol
DO 3 7
0.1
100
2,4, 6-TrichlorophersoI
D041
0.05
400
D042
0.05
2.0
Base neutral fraction:
1,4 Dichlorobenzene
B027
0.025
7.5
2,4-Dinitrotoluene
B030
0.025
0.13
Hexachlorobenzene
D032
0.025
0.13
Hexachlorobutadiene
D033
0.025
0.5
Hexachloroethane
D034
0.025
3.0
Nitrobenzene
D036
0.025
2.0
Pyridine
0038
0.025
5,®
Pesticides
Chlordane
D020
0.0005
0.03
Endrin
DO 12
©.0001
0.02
Heptachlor
D031
0.0001
0.008
Lindane Igwana-BHC)
D013
0.0001
0.4
Me thoxychlor
D014
0.0005
10.0
Toxaphene
D015
0.005
0 .5
Herbicide*
2,4-D
0016
0.905
10.0
2,4,5-TP (Silex)
D017
0.005
1.0
Metal*
Arsenic
DO 04
0.005
5.0
Barium
DO 05
0.01
100
Cadnium
D006
0.01
1.0
Chromium
D007
0.01
s.o
Lead
D008
0.08
5.0
Mercury
DO 09
0.0004
0.2
Selenium
D010
0.01
1.0
1 Silver
D011
0.01
5.0
a. Established MDLs are based on reagent grade water; achieving MDLs is
matrix dependent.
7-18
-------
The results of the homogeneous woods analysis are useful in determining
possible sources of contamination in the waste wood stream. Tables 7-3
through 7-8 summarize the laboratory work performed on the samples collected
for this project.
7.5.1.1 Ulti.ma.te/Proximate Analysis
One of the most outstanding features of these analysis is the consistency of
the heating values for the different wood types. On a moisture-free basis
these values are in a narrow range between about 8280 Btu/lb to 9430 Btu/lb.
Even on a wet basis these samples were within a 1000 Btu range with the
exception of the telephone pole analysis. This particular telephone pole
saropie had a very high moisture content of 29 percent, more than double chat
of any other sample. This telephone pole sample also stands out from the
other samples because it had unusually high ash and chlorine content {2.41 dry
weight percent ash and 0.41 dry weight percent chlorineJ,
from an environmental impact standpoint, sulfur, chlorine, and ash values are
the most important numbers in these tables. With the exception of the
creosote-treated woods, the sulfur content in all of these samples is below
0.08 dry weight percent. Thus high levels of sulfur in a waste wood stream
could indicate either creosote-treated materials or non-wood contaminants such
as tarpaper, shingles, and asphalt. The high chlorine values for the
laminated wood may be due to either PVC coating of the wood or chlorine found
in the resin. The bonding agent may also be the chlorine source in the
particle board samples.
All these samples have a low ash content. Thus the higher ash contents found
in C/D wastes and other waste woods may be the result of either paint, dirt or
other noncombustibles in the waste wood stream (see Section 7.4.2). In
theory, part of the noncombustibles can be removed using float tanks,
trommels, or disk screens. Increased processing to remove fines and other
dirt should reduce the ash content of waste wood streams close to that of pure
wood. However, the remaining ash could contain a higher metals concentration
value due to less inert dilution and thus be more toxic.
7.5.1.2 Phenols
fable 7-5 presents the results of phenols analysis for several wood types.
Every value shown is at the detection limit below which the laboratory could
not analyze. The absence of detectable phenols shows that these samples do
not have free or leachable phenol based materials and have not been
contaminated with other phenol based chemicals. It was expected that samples
containing phenol based resins used as bonding agents or as treatment
chemicals (plywood and pentachlorophenol materials) should have had some free
phenol available for analysis. It may be that the woods tested utilized other
resin combinations or that residual phenol levels were below the detection
limit.
7.5.1.3 Minerala Analysis of Facility and Laboratory Ash
Table 7-6 presents the results of minerals analysis. Note the low values of
silicon present in the ash. This would seem to verify the assumption that
most of the silicon present in the ash of waste wood is due to dirt being
processed with the wood. In most cases calcium seems to be the primary
component. Titanium dioxide, an indicator of modern paints, is found in very
small amounts except in the ash from the furniture manufacturer and the ash
from the facility burning laminated wood. The furniture waste material was a
fine sawdust so it was impossible to determine if paint was present.
However, the laminated wood had visible paint pigmentations.
7-19
-------
Carbon dioxide values are the result of calcium carbonate and magnesium
carbonate compounds present in the ash.
The minerals analysis of the CCA pressure treated woods is very puzzling. The
ash from the first sample sent to the laboratory was reported to have 63.85
weight percent manganese oxide content.. Assuming a laboratory error had
occurred, a duplicate sample of the ground material was sent for analysis.
This turned out to be nearly the same at 62.83 weight percent manganese oxide.
At this time no explanation can be offered for these results. A third sample
of CCA pressure-treated wood was procured from another source and analyzed.
Only 19.34 percent of the ash generated from this third sample consisted of
compounds normally tested for in a minerals analysis. The results of the
concurrent elemental metals analysis indicate that the ash is 34.5 percent
oxidized chromium and 13.4 percent copper oxide. Ash from the fire-
treated/pressure- treated wood sample was determined to be 80.6 percent
oxidized phosphorus (P2Os) or 3 5 percent by weight phosphorus.
7.5.1.4 Elemental Metals Analysis
Table 7~? presents the results of the elemental metals analysis. With the
exception of the analysis of the laminate wood and its fly ash, CCA-treated
wood and creosote-treated woods, most of the metals analyses were very near or
below the detection limits. It is assumed that the metals concentrations in
the laminated wood and asti result from the variety of paint pigments in the
wood sample.
Of the creosote treated woods only telephone poles showed any significant
contamination of metals, these being lead and zinc. It is possible that
telephone poles generally located adjacent to roadways may have adsorbed
vehicular engine metal particulate emissions from the atmosphere in which they
existed. Additional testing of telephone poles would be required, however, to
prove this theory.
As would be expected, the CCA treated (chromated copper arsenate) wood
demonstrated high levels of chromium, copper, and arsenic. Industry standards
show that 0.4 to 3 percent of the CCA treated wood should be CCA solution.
The average fraction of the CCA metals in the two pressure treated samples was
0.43. This is within industry standards (AWP, 1988). Using this average
value for arsenic, chromium, and copper it is possible to estimate the percent
contamination of a waste wood stream by CCA. This assumes all of the arsenic,
chromium and copper are the result contamination of CCA treated woods. This
calculation was made in the following section on the heterogeneous waste wood
samples to estimate possible CCA contamination levels.
7.5.1.5 Toxic Characteristic Leachate Procedure (TCLP)
In Table 7-8, the results of the leachate test on the four treated samples
tested show that only the CCA pressure-treated samp]e may come close to being
considered characteristically hazardous by the TCLP test. This sample had an
arsenic level of 8 mg/L {regulatory level is 5 mg/L} and had a relatively high
chromium value. The regulatory level for chromium is 5 mg/L; this sampled
tested at 4.10 mg/L chromium. The TCLP test allows for failure of the arsenic
•value for CCA wood provided no other metals or organic failures occur.
7.5.2 Waste Wood Processors
This section summarizes the analytical findings for each of the processors
visited. Each subsection contains tables of averaged data and site specific
conclusions that can be inferred from this data. A summary section follows
where all the data collected from the processors are discussed and general
7-20
-------
Table 7-3. Homogeneous woods ultimate and proximate analysis. Percent by weight as received.
Sample type
Volatile
Fixed
carbon
Moisture
Total
carbon.
Hydrogen
Nitrogen
Sulfur
Ash
Oxygen (by
difference)
Chlorine
Heating
value
(Btu/lb)
Plywood scraps
73.41
17.40
7.81
50.46
5.65
0.29
0.04
1.38
34.37
0.03
S461
Pressure treated 1
68.66
13.91
14.14
47.37
5.18
0.21
0.03
3.27
29.80
0.09
A03 9
Pressure treated 2
74.69
16.64
7.75
47.02
5.78
0.21
0.02
0.92
38.30
-
7702
Fire treated
63.4?
27.74
7.65
46.35
5.76
1.75
0.01
1.14
37,34
7647
Particle board <3,
hardwoods)
7S.33
18.14
6.31
48.56
5.44
2.77
0.03
0.22
36.67
0.31
7790
Particle board S3.
pine fine)
74.19
18.5?
6.73
49.42
5.68
2.75
0.03
0.51
34.88
0.12
8247
Particle board (S,
pins medium)
73.41
19.34
6.89
51.22
5.26
2,94
0.03
0.36
33.30
0.17
3357
Particle board (S.
pine coarse)
74.57
18.07
6.47
50.05
5.54
3 .27
0.07
0.89
33.71
0,11
8368
Telephone poles
55.80
13 . 51
2d .98
39. S3
4.28
0.31 '
0.40
1.71
24.80
0.29
6667
R.R. ties
72.03
13.60
13.16
48.71
5.26
0.41
0.10
1.19
31.15
0 .03
8191
Birch turn. plywood
81.40
13.64
4,60
48.89
5.67
3.32
0.01
0.36
37.15
0.15
7 9 27
Furniture waste
71.9?
15. 66
IX. 21
45.18
5.44
1.42
0.02
0,96
35,77
0.05
7484
Laminated wood
69.68
18.24
10 .73
44.38
5.43
3 .00
0.04
1.35
35. 07
0.24
7484
-a
(
Table 7-4. Horageneous woods ultimate and proximate analysis. Percent by weight dry basis.
Sample type
Volatile
Fixed
Total
Hydrogen
Nitrogen
sulfur
Ash
Oxygen,
Chlorine
MAP
Heating
Alkaline
cartoon.
carbon
by
BtU/lb
value,
•s NaO
difference
Btu/lb
Plywood scraps
79.63
18.87
54.74
6.13
0,31
0.04
1,5
37,28
0.03
9318
9178
0.46
Pressure treated 1
7 9.97
16.22
55.17
6,03
.025
0,03
3.81
34.71
0.1
9734
9363
0.08
Pressure treated 2
ao.9 6
18.04
50.97
6.27
0.23
0.02
1
41,51
_
8433
8349
-
Fire treated
68,73
30.04
50,19
6,24
1.89
0.01
1.23
40.44
-
83 83
8280
_
Particle board (S.
hardwoods!
SO.4
19.36
51.83
5,81
2.96
0.03
0.24
39,13
0.33
8335
831S
0,05
Particle board (S.
pine fin#)
79.54
19.91
52.99
6.09
2,95
0.03
0,55
37.39
0.13
8891
8842
0.12
Particle board (S.
pine medium)
78.84
20.77
55.01
5.65
3.16
0.03
0.39
35.76
0.18
9010
8975
0.07
Particle board IS.
pine coarse!
.73.73
19.32
53.51
5.92
3.5
0.08
0.95
35.04
0.12
9033
8947
0.1
Telephone poles
78.57
19.02
55.65
6.02
0,44
0.56
2.41
34.92
0.41
964B
9415
0,42
R.R. ties
82.96
15,67
56.11
6.06
0.47
0.12
1,37
3 5.87
0.04
9565
9434
0,04
Birch furn. plywood
§8.32
14.3
51.25
5,94
3.48
0.01
0.38
3 8 . 94
0,16
8341
8309
0,06
Furniture waste
SI, 06
17.86
50,88
6.13
1.6
0,02
1.08
40.29
0.06
8521
8429
0.11
Laminated wood
78.05
20.44
49,71
6, OS
3.36
0,05
1.51
39.29
0.25
8 513
8384
0.09
-------
fable 7-5. Homogeneous woods phenols and chlorophenols analysis, ug/g dry. {Negative values represent
detection limits.}
Saaple type
Phenol
2-
2-
2,4-
2,4-
4-
2,4,6-
2,4-
4-
2-
P«mta-
chloro-
Nitro-
Dinethyl-
Dichloro-
Chloro-
Tri-
di-
Nitrop-
Mathyl-
chlor-
phenol
phanol
phenol
ph«nol
3-
msthyl-
phenol
chloro-
pheaol
nitro-
phenol
benoi
4, 6-
dintro-
phertol
phenol
Plywood scraps
-1.32
-1.32
-1.32
-1.32
-1.32
-1.32
-1.32
-6.®
-6.8
-fi.B
-6.8
Pressure treated I
-6.6
-6.6
*6. $
-6.6
-6.6
-6.6
-6.6
-34
-34
-34
-34
Particle board (S.
hardwoods)
-3.3
-3.3
-3.3
-3.3
-3.3
-3.3
-3,3
-17
-17
-17
-17
Particle board (S.
pine fine)
-1.98
-1.98
-1.98
-1.98
-1.98
-1.98
-1.98
-10.2
-10.2
-10.2
-10.2
Particle board (S.
pine medium!
-1.32
-1.32
-1.32
-1.32
-1.32
-1.32
-1.32
-6.8
-6.8
-6.8
-6.8
Particle board (S.
pine coarse)
-1.98
-1.98
-1. 90
-1.98
-1.98
-1.98
-1.98
-10.2
-10.2
-10.2
-10,2
Telephone poles
-2.31
-2.31
-2.31
-2.31
-2.31
-2.31
-2.31
-11.9
-11.9
-11.9
-11.9
R.F. ties
-2.97
-2.9?
-2.97
-2.97
-2.97
-2.97
-2.97
-15.3
-15.3
-15.3
-15.3
Birch turn, plywood
-0. 33
-0.33
-0.33
-0.33
-0.33
-0.33
-0.33
-1.7
-1.7
-1.7
-1.7
Furniture waste
-2.31
-2.31
-2.31
-2.31
-2.31
-2.31
-2.31
-11.9
-11.9
-11.9
-11.9
-a
i
to
M Table 7-6. Homogeneous woods mineral analysis of laboratory combusted material and facility ash, % by weight Of
oxides in ash.
sample type
Si
A1
Ti
Pe
ca
«a
K
Na
S
F
fcfra
to,
Cu
Sr
Ba
Unde-
t*r-
mined!
Loss
on
igni-
tion
Plywood acraps
9.2
1,93
0.16
1.0}
53,6
2.8
o.n
7.96
0.18
0.6
1.72
19.6
Pleasure treated 1
7. OS
6.3
0.6
6.86
4
i
2.6
0.44
0,2
2.08
63. §5
3.13
2.89
t duplicate
7,35
s.sa
0,62
7.
4
l
2,52
0,52
2.74
0.3
62.83
3, as
1,51
fissure treated 2
0, 86
0.4
€.03
0.7
8,26
2.K
2.0$
0.65
0.8
3,02
0.48
0. 04
0.06
80.48
Fire tlegated
£.3?
0.41
0.f»3
0.86
7,35
1.62
S.93
2.47
0.15
30.64
0.33
0.04
0,1
1.67
Particle board CS-
haidwoods}
9.06
2,63
0.52
4
25.2
8,«
13,4
li.2
3.43
2.24
1.39
0.73
Particle board is. pirn
tine)
1
l.S
0,24
1*72
24
8
10
15.6
5,4®
8
2,64
15,€
0.21
Particle board IS, pine
10. u
2.07
0.32
3, as
26
9.2
8.56
12.56
4.39
2,11
14
§.7
rant tele board CS.pirs©
coarse 1
25-61
4.9
0,52
1.74
27.6
g
9.12
4.04
10.5*
2.0
3.01
2.2
114
Telephone poles
19. 73
3,91
0.36
22 64
8
3.6
2.42
16
20.44
0.3
2.54
7.16
R.R. t ies
3 J . 08
7.11
0.52
71.16
20.8
3.6
2.09
1,62
6.58
0.8
0.62
1.1
0.9
Bitch furn. plywood
4.02
0.75
0,40
i. n
40
7,.52
18.4
2.88
4.9 i
10
9.31
t'urnituxe waste
12-3?
15.0J
28
5.54
14.6
?,24
6
A SI
0.1
2.2
0.93
Laminated wood
18,45
9.43
25. 65
2.46
26.57
3.68
2.8?
1.57
1.28
1.89
1.07
2.1
-------
Table 7-7. Homogeneous woods elemental metals analysis, ppm dry basis. Negative values are detection limits.
Sample type
Ar»«nic
Baritaa
Cadmium
Chromiwt
Copp»r
Lead
Mercury
Titanium*
Nickel
zinc
Silver
Plywood scraps
7.2
11.1
-0.05
8.5
2.5
7.5
-0.25
1.19
-5 •
8.5
-0.05
Pressure treated 1
2050
«
-0.5
1740 .
1040
13
-0.25
-1
-5
20
0.09
Pressure t reat®d 2
290
3
0.2
2357
1073
2.16
0.11
18
0.73
3.67
-0.1
Fire treated
10
1?
ft.3
31.7
64.5
1.2
0.03
17.22
0.85
11.84
20.1
Particle board {S.
hardwoods i
-0.25
27.4
-0.05
-5
-2.5
€.5
-0.25
-0.35
-5
7.5
-0.05
Particle board (S.
pine fine)
-0.25
10.9
-0.05
-5
-2.S
-5
-0.25
-0.25
-5
10.5
-0.05
Particle board (S.
pine medium)
-0.25
9.1
-o.os
-5
-2.5
-5
-0.25
-0.25
-5
11.5
-O.OS
Particle board
-------
conclusions about waste wood are made. Appendix G contains all the individual
data sets for each of the sites.
7.1.2.1 Processor - Sit# 1
This processor sells most of its product to licensed combustion facilities and
does not limit the wood types used in its product. Any wood shipped to the
facility is processed. The facility also buries some of its C/D wastes for a
period of time until paper and other similar types of contaminants are removed
by natural decay. .As a result, some of the materials produced at this site
have a high dirt content. All the available processed wood fuel and fine
grade wood chips {used for landscaping} were included in the sampling program.
Additionally, samples were taken directly from both the fines and wood fuel
process conveyors.
Tables 1-9 through 7-12 present the results of the sampling at Site 1. As
expected, che variance in ultimate/proximate analyses is quite low. The
greatest variation occurs in the moisture and ash content of the wood.
Variation in moisture content is not unusual and is not normally a parameter
of environmental concern. High ash and sulfur contents, however, generally
indicate the presence of non-wood contaminants ill the fuel. Pure wood
typically contains 1 percent to 2 percent ash and less than 0.10 percent by
weight sulfur. The percent ash at site 1 averaged 5.16 percent by weight and
the average sulfur content was 0.12 percent by weight. The ash content is
consistent with that found at the other facilities. The sulfur content
suggests the presence of sulfur-containing materials such as creosote and
pentantachlorophenol treated wood or asphalt, tarpaper, or walIboard.
Chlorine was also detected in small amounts and would suggest the presence of
FVC plastics cr treated/glued woods containing chlorine materials {particle
board, and laminated wood, etc.).
Of the phenol compounds tested, only phenol was detected in small amounts.
Three of the four samples showed the presence of phenol in the wood. The
sample that was measured below detection limits for phenol was reanalyzed and
again proved to be less than the detection limit. The small amount of phenol
in these samples may indicate the presence of particle board or plywood with
some free phenols or the presence of some chemical contaminants; however, the
extremely low phenol values would not be of any environmental concern.
the results of the minerals analyses indicate that silicon and calcium are the
two principal components of the ash which is generally typical of wood fuel,
with the silicon mainly attributed to soil and dirt processed with the wood
stream. The minerals analysis of the fines material produced at the site
shows a much higher silicon content than the coarse material. The silicon
content of the fines materials ash was 53.1 percent compared to the silicon
contents of 35.70 percent and 35.28 percent in the coarse material ash. The
results are not surprising since some of the feedstock processed was buried on
the site and dug up. Also the separation of the fines material from the waste
wood stream concentrates loose soil into the fine product.
Metals analysis of the wood from this site indicated a wide variation of
metals concentration. Of the 11 metals tested, three (cadmium, mercury, and
silver) were below detection limits. Only one sample had a nickel content
above detection limits and that result could not be duplicated when the sample
was reanalyzed. The other seven metals were detected in relatively large
quantities. Arsenic, chromium, lead, zinc, and barium, levels were all
significantly higher than the average of all the other facilities sampled in
the program. This again is not surprising since this facility does not limit
the types of C/D materials being accepted.
7-24
-------
Table 7-9, Processor Site I,
Wood ultimate analysis
Average
Standard
deviation
Minimum
Maximum
Number of
samples
As received
% moisture
19.40
3.77
15.37
23.17
4
Btu/lb
663?
276
6300
6915
4
Dry basis
% carbon
50', 28
1.58
48.77
52.34
4
% hydrogen
5,92
0.20
5.68
6.11
4
% nitrogen
0.46
0.09
0,36
0.58
4
% sulfur
0,12
0.03
0.08
0.14
4
% ash
5.16
2,91
1.84
7.€4
4
% oxygen {difference}
38.07
1.23
36.73
39.22
4
% chlorine
0,08
0.03
0.06
0.12
4
% volatile
79.59
2.07
77,23
81.91
4
% fixed carbon
15.25
1,07
13.80
16.25
4
Btu/lb
8238
222
8034
8503
4
Phenols in wood
Average
Standard
Minimum
Maximum
Number of
ug/s
deviation
pg/g
ug/o
samples
Phenol®
0.90
0,51
0.33
1.60
5
Pentachlorophenol
<3.06
-
<1.70
<5.10
5
2-chlorophenol
<0.60
<0.33
<0.99
5
2-nitrophenol
<0.60
-
<0.33
<0.99
S
2,4-dimethylphenol
<0,60
_
<0.33
<0.99
5
2,4-dichlorophenol
<0.60
-
<0.33
<0.99
5
4-chloro-3-methylphenol
<0.60
-
<0-33
<0.99
5
2,4,6-trichlorophenol
<0.60
-
<0.33
<0.99
5
2»4-dinitrophenol
<3.06
-
<1.70
<5.10
5
4-nitrophenol
<3.06
_
<1.70
<5.10
5
2-methyl-4,6-dinitrophenol
<3.06
-
<1.70
<5,10
5
Mineral analysis off laboratory ash.
Average
Standard
Minimum
Maximum
Number of
% by wt.
deviation
% by wt.
% by wt.
samples
Silicon dioxide
41.36
8.30
35.28
53.10
3
Aluminum oxide
7.58
0.72
6.73
8.49
3
Titanium dioxide
1.18
0,27
0.84
1.50
3
Iron oxide
8.67
0.85
7.83
9.83
' 3
Calcium oxide
15.44
4.20
9.52
18.80
3
Magnesium oxide
3,97
1.31
2.24
5,40
3
Potassium oxide
3.47
0.62
2.60
3.92
3
Sodium oxide
3.21
0.61
2.50
3.99
3
Sulfur tricxide
8.56
1.60
6.32
9.96
3
Phosphorus pentoxide
0.95
0.25
0.60
1.16
3
Lead oxide
0.46
0.13
0.32
0.64
3
zinc oxide
0.68
0.15
0.52
0.88
3
Manganese oxide
-
-
-
-
-
a. Analyses below detection limit were assumed to be % the detection limit
for calculation purposes.
7-25
-------
Table 7-10, Summary data from Processor Site 1,
Total metals analysis, ppai in dry wood.
Metal
Number
Arithmetic
Stanndard
Minimum
90"'
85"'
Maximum
Median
Geometric
Lognormal
of
average
deviation
detected"
percen-
percen-
detected
confidence
B»ai»
mvu mean"'
samples
tile
tile
Median"
Arsenic
8
68.73
85.82
3
262.5
262. 5
262.5
43
86.77
29.89
81.13
Chromium
8
104.44
79.54
10
233
233
233
92
148.77
74.03
123.50
Lead
8
266.19
93.19
127
405
405
405
264.5
324.61
250.47
267.30
Titanium"'
8
49.51
59.37
11
191.75
191.75
191.75
29.4
59.51
32.77
45.79
Titanium*
8
279.6
131,36
132
385
385
385
_
.
-
Zinc
S
176.63
91.90
66
366
366
366
158.5
222.48
157.65
176.72
Bart-am
8
435.63
153.89
240
630
630
630
485
531.58
409.21
437.23
Cadmium*
8
1.50
-
1.5
1.5
1.5
1.5
1.5
1.50
1.50
1. 50
Copper
8
44.00
35.50
17
125
125
125
30.5
54.87
3 5.83
€2. 63
Mercury"
0
0.025
•
0. 025
0.025
0.025
0.025
0.025
0.025
0.02 5
0.025
Nickel
8
7.69
7.60
26. 5
26.5
26.5
26. 5
5
9.14
6.16
7.15
Silver4
8
2. 500
-
2.5
2.5
2.5
2.5
2.5
2.50
2.50
2.50
Five metals analysis, ppm In dry wood.
Metal
miabmx
Arithmetic
Stanndard
Minimum
90"'
85"
Maximum
Median
Upper
Geometric
Lognormal
of
average
deviation
detected*
percen-
percen-
detected
confidence
mean
MVU Mean*
sanples
tile
tile
median1*
Arsenic
16
112.83
181.37
0.7
328
662
662
23
64.22
22.36
178 . 96
Chromium
16
126.75
149.27
4
453
475
475
71
118.30
60.04
149.57
Lead
16
430.44
514.60
84
709
2250
2250
283.5
43 7.94
304.99
399.19
Ti tanium*
16
116.08
1S8.54
2.6
443
537
537
42.45
98. 61
50 .12
124,38
zinc
16
S00.25
657.39
44
1920
2100
2100
235
447.63
2 62,88
456.07
a. In cases where samples registered below the detection limit, one-half of the detection limit was used.
b. Level for which there is 95% confidence that the median of any similar random sampling will show a
lower value.
c. The Minimum Variance Unbiased (MVU) estimator of the true median for a lognormal distribution
(Gilbert, 1987).
d. Values are suspect, see text in section 7.4,
e. Calculated from minerals analysis.
f. Meaningless, since most of the data are below detection limit.
-------
Table 7-11. Processor Site 1 average incremental versus composite metals
analysis.
Segment 1
Incremental
Incremental
Combine
Percent
range, ppm
average*, ppm
segment, ppm
di fference
Arsenic
17.6-662
297.5
262.5
13.3
Chromium
46-475
249.3
211.5
17.9
Lead
182-292
240.3
220.5
9.0
Titanium15
59.1-443
217.3
191.8
13.3
Zinc
107-1900
442.8
213
107.9
Segment 2
Incremental
Incremental
Combine .
Percent
range, ppm
average®, ppm
segment, ppm
difference
Arsenic
21-119
59
68
-13.2
Chromium
61-115
80.5
86
-6.4
Lead
210-561
336.3
249
35.1
Titanium13
18- 45.8
28.9
19.5
48.2
Zinc
105-405
236.3
140
63.8
Segment 7
Incremental
Incremental
Combine
Percent
range, ppm
average8, ppm
segment, ppm
difference
Arsenic
1.1-25
12 •
3.3
263.6
Chromium
11-80
58.3
41
42.2
Lead
141-2250
838
344
143.6
Titanium6
39.1-537
203 .3
56.1
262 .4
Zinc
216-2100
1122.5
177
534.2
Segment 8
Incremental
Incremental
Combine
Percent
range, ppm
average*, ppm.
segment, ppm
difference
Arsenic
0.7-328
82.8
26
218.5
Chromium
4-453
119
106
12.3
Lead
84-709
307.3
280
9.8
Titanium®
2.6- 31.4
14.9
11
35.5
Zinc
44-480
199.5
120
66.3
a. Arithmetic mean based on 4 samples.
b. Titanium values are suspect. See text.
The highest concentration of any one metal found in the composite samples
{total metals test) was 630 ppm of barium. This metal is found naturally in
wood and is not normally indicative of non-wood contamination of fuel.
However, the mean value of 43 7 ppm is at least five times greater than levels
in clean wood and about three times greater than the mean of all the tested
facilities, No explanation for such high levels of barium is evident. It is
interesting to note that the two highest values detected for barium were from
samples of fines material. In fact, the highest concentrations of each metal
were found in the fines samples Isegments 1 and 7).
1-21
-------
Lead, titanium, and zinc are component* in waste wood suspected to originate
from the inclusion of painted woods in the fuel. For this site these elements
had a geometric mean concentration of 250, 35 and 160 ppm by weight,
respectively in the waste wood.
Table 7-12. Processor Site 1 Toxic Characteristic Leachate Procedure (TCLP) in
laboratory ash {heavy metals I, mg/1.
Metal
Average
value*
Maximum
Detection
limit
U.S. EPA
limit
Number of
samples
Arsenic
ND
ND
0.5
5
3
Barium
ND
ND
1
100
3
Cadmium.
ID
ND
0,2
1
3
Chromium
30.93
46
0,2
5
3
Lead
5.33
14
2
5
3
Selenium
ND
ND
0.5
1
3
Silver
ND
ND
0,1
5
3
Mercury
ND
ND
0.1
0.2
3
a Analyses below detection limit were assumed to be % the detection limit
for calculation purposes.
The high values of arsenic, copper, and chromium indicate that some portion of
the processed wood contains CCA pressure-treated wood. By conservatively
assuming that 100 percent of these elements are the result of CCA
contamination and using representative values from the analysis of pure
pressure-treated wood, it is possible to estimate what percent of the waste
wood is CCA treated. The resulting values range from 0,03 percent to 28.9
percent CCA treated wood in the composite samples with an average of 6.1
percent. However, by removing the influence of segment 1, the average
calculated CCA contamination drops to 3,6 percent, whereas the average for
segment 1 alone is 14,9 percent.
Comparing the minimum and maximum values for each of the metals in the "five
metals" versus the "total metals" analyses, the "five metals" results vary
over a much greater range. The "total metals" analyses are performed on
composited samples whereas the "five metals" analyses are performed on non-
composited samples. Also in most instances the averages and geometric means
of the composited samples were less than the non-composited values for the
same metals. It is presumed that the thorough compositing of the segment
samples diminished the effects of any outlyers from contaminated wood and, in
effect, produced a median result.
The results of the TCLP tests on laboratory ash for this facility show
failures for chromium and lead, chromium levels in the leachate were as high
as 46 mg/L averaging 30,93 mg/L while lead levels were as high as 14 zag/L
averaging 5.33 mg/L. The USEPA regulatory limit for both these metals is 5
mg/L.
7.5,2,2 Processor - Site 2
7-28
-------
site 2 solely produced wood chip fuel to be sent to a licensed combustor. The
facility has 110 restrictions on the wood it accepts and processes a
significant amount of telephone poles and C/D wood waste. Cross sections of
all the available processed wood product were sampled as well as sampling
directly from the process conveyor.
Tables 7-13 through 7-16 present the results of the sampling at site 2.
Similar to site 1, the variance in the ultimate/ proximate analyses is low and
the greatest variation occurs in the moisture and ash contents. Moisture, as
previously stated, is riot usually considered a parameter of environmental
concern. The ash content for wood from this site varies dramatically from 2
percent to 21 percent dry weight, averaging 7.38 percent, which indicates the
presence of non-wood' contaminants is not evenly distributed in the fuel.
However, the low sulfur 10,06 percent) and chlorine (0.03 percent) values
suggest that materials such as asphalt, tarpaperF wallboard and PVC plastics
are being separated out of the processed waste wood fuel.
Pentachlorophenol was the only phenol compound detected in all four samples.
This is an indicator of penta-treated wood in the fuel, possibly from
telephone poles and railroad ties being hogged at the site for disposal. The
absence of other detectable phenols suggests an absence of phenol-based
chemical contamination of the wood.
The results of the minerals analysis show very high levels of silicon dioxide
compared to the average of the facilities which suggests that a sizable amount
of dirt is being processed with the wood. This facility is equipped with disk
screens and a shaker tower which apparently are not removing enough of the
entrained dirt.
The metals analysis for this site indicates"a high level of metals
contamination. Of the eleven metals tested, only mercury was below detection.
The lowest values detected for arsenic and lead in the composite samples are
greater than the upper confidence limit of the median calculated for all six
processors. The maximum detected levels for lead, titanium, zinc, cadmium,
and copper are the highest of all six processors. The average value cf copper
is four times that of all six processors. Arsenic, lead, and zinc values are
twice as high. All these values indicate a heavy contamination of paints with
titanium, lead and zinc compounds and of CCA and penta-treated woods.
Using representative values from the analysis of CCA treated wood, estimates
of CCA contamination were calculated for this site. Assuming 100 percent of
the copper, chromium, and arsenic are the result of CCA treated wood, the wood
from this facility ranges between 0.50 percent and 13.4 percent CCA averaging
4.83 percent and excluding an outlying value of 312.3 percent, actually a
lesser amount of CCA than seen at site 1.
Judging from the results of not only the "five metals" incremental analysis
but also the composite analysis as well, it can be seen that the fuel mix at
this site is extremely heterogeneous. Even though the composite analyses vary
over a wide range, it is still more narrow than the range of the incremental
analyses which again suggests that the compositing of samples is a more
accurate means of determining facility averages.
The results of the TCLP tests on laboratory ash from this facility show
failure for chromium. Chromium levels in the leaehate were as a high as 11
ujg/L averaging 7.65 mg/L. It is unknown why this ash demonstrated no leaching
of lead even though lead levels were twice as high as site 1 which failed the
TCLP for lead.
7-29
-------
Table 7-13. Processor Site 2.
Wood ultimate analysis
Average
Standard
deviation
Minimum
Maximum
Number of
samples
As received
% moisture
19.84
4.71
15.47
25.38
4
Btu/lb
6889
331.75
6434
7145
4
Dry basis
% carbon
50 . 55
2.28
47.49
52.67
4
% hydrogen
5.95
0.36
5.42
6.20
4
% nitrogen
0.53
0.02
0.51
0.56
4
% sulfur
0. 06
0.01
0.06
0.07
4
% ash
7.38
9,26
1.97
•21.17
4
% oxygen (difference)
35.54
6.84
25.30
39.53
4
% chlorine
0.03
0.02
0.02
0.06
4
% volatile
80.53
2.26
77.80
82.51
4
% fixed carbon.
12.09
7.38
1.03
16.13
4
Btu/lb
8599
147.47
8453
8794
4
Phenols in wood
Average
Standard
Minimum'
Maximum
Pumber of
ug/g
deviation
pg/g
pg/g
samples
Phenol®
<1
.4
<0.99
<1.98
4
Pentachlorophenol
25
.85
15
.35
6.40
43.00
4
2 -chlorophenol
<1
.4
<0,99
<1.38
4
2-nitrophenol
<1
.4
<0.99
<1.98
4
2,4-dimethylphenol
<1
.4
<0.99
<1.98
4
2,4-dichlorophenol
<1
.4
<0.99
<1.98
4
4-chloro-3-mathylphenol
<1
.4
<0.99
<1.98
4
2,4,6-trichlorophenol
<1
.4
<0.99
<1.98
*4
2,4-dinitrophenol
<7
. 22
<5.10
<10.20
4
4 -ni tropheno1
<7
.22
<5,10
<10,20
4
2-methyl-4,6-dinitrophenol
<7
.22
<5.10
<10.20
4
Mineral analysis
of laborato
ry ash.
Average
Standard
Minimum
Maximum
Number of
% by wt.
deviation
% by wt.
% by wt.
samples
Silicon dioxide
63.24
3.16
61.00
65,47
2
Aluminum oxide
10.31
0.01
10.30
10.31
2
Titanium dioxide
1.24
0.57
0.84
1.64
2
Iron oxide
5.46
0.61
5.03
5.89
2
Calcium oxide
7.26
1,05
6.52
8.00
2
Magnesium oxide
1,46
0.31
1.24
1.68
2
Potassium oxide
2.98
0.01
2.97
2 . 99
2
Sodium oxide
2.29
0.02
2-27
2.30
2
Sulfur trioxide
3.80
0.25
3.62
3.97
2
Phosphorus pentoxide
0.38
0.04
0.35
0.40
2
Lead oxide
1.03
0.97
0.34
1.71
2
Zinc oxide
_
_
-
-
Manganese oxide
-
-
-
-
-
a. Analyses below detection limit were assumed to be % the detection limit
for calculation purposes.
7-30
-------
Table 7-14, Summary data from Processor Site 2,
Total metals analysis, ppm in dry wood.
Metal
Number
Arithmetic
Stanndard
Minimum
90"
85th
Maximum
Bedian
Upper
Geometric
Lognormal
of
•vorata*
deviation
detected"
percen-
percen-
detected
confi-
mean
MVU mean'
samples
tile
tile
dence
median1"
Arsenic
8
78.64
S3.57
19.1
157.3
157,3
157.3
65,25
104.66
61.28
80.37
chromium
S
49.44
32.35
12.5
8S.5
89.5
89.5
38.5
65.56
39.35
50.39
Lead
a
57 2
318.94
248. S
1300
1300
1300
526,75
708.50
512.63
567.07
Titanium4
8
24.73
17.65
8.7
63.7
63.7
63.7
23.1
31.71
20.31
24.55
Titanium*
8
633 . 7
281.6
202
1066
1066
1066
-
_
_
-
Sine
8
283.5
228,89
103
800
800
800
212.5
353.75
234.76
275.76
Barium
8
117.25
57.75
45
226
226
226
108
147.^3
105.25
117.57
Cadmium.
8
0.87
0.53
0.25
2
2
2
0.7
1.12
0.74
0.87
Copper
8
455.75
1149.38
25
3300
3306
3300
50.5
223.51
79.23
204.86
Mercury
8
0 . 125
0.125
0.125
0.125
0.125
0.125
0.125
0.125
0..12S
Nickel
8
5 . 63
6.89
2.5
22
22
22
2. 5
6.57
3.79
5.04
Silver
8
0, 3G2
0,24
0.028
0.65
0.65
0.65
0.2R5
0.42
0.19
0.34
Five metals analysis, ppn> in dry wood.
Metal
Number
Arithmetic
Stanndard
Minimum
90"
85-*
Maximum
Median
Upper
Geometric
Lognormal
of
average
deviation
detected*
percen-
percen-
detected
confidence
mean
MVU mean"
samples
tile
tile
median*
Arsenic
16
118.01
114.63
0.125
280.45
3 60.6
360.6
59.75
122.87
45. 50
29 3.38
Chromium
16
56.47
49.64
2.5
144
146.5
146.5
37.5
60.48
35.41
63 . 1ft
Lead
16
594.89
5C2.69
141
1315
1970
1970
428.875
642.20
448.66
584.53
Titanium*
16
17.28
11.63
5.7
40.3
42.8
42 .8
13 .75
19.20
14.37
17 . 10
Zinc
16
217.25
118.58
86
440
455
455
174.5
244.38
190.57
216,64
a. In cases where samples registered below the detection limit, one-half of the detection limit was used.
b. Level for which, there is 95% confidence that the median of any similar random sampling will show a
lower value,
c. The Minimum Variance Unbiased (MVU) estimator of the true median for a lognormal distribution
{Gilbert, 1987}.
<3. Values are suspect, see text in section 7.4.
e. Calculated from minerals analysis.
t. Meaningless, since most of the data are below detection limit.
-------
Table 7-15. Processor Site 2 average incremental versus composite metals
analysis.
Segment 1
Incremental
range, ppm
Incremental
average3, ppm
Combine
segment, ppm
Percent
difference
Arsenic
219.1-360.6
271.7
154
76.4
Chromium
86.5-146.5
126.5
91.25
38.6
Lead
187.5-444
323.1
334.75
-3,5
Titanium13
7.8- 14.5
10.9
13.9
-21.6
Zinc
124 -190
151.8
223
-31.9
Segment 2
Incremental
Incremental
Combine
Percent
range, ppm
average3, ppm
segment, ppm
difference
Arsenic
44.1- 198.5
102.9
81.1
26.9
Chromium
21.5- 51.5
38.4
45
-14.7
Lead
260.5-1315
715.4
575.5
24.3
Titanium6
12.5- 40.3
24.8
26.4
-6.1
Zinc
162 - 380
270.5
240
12.7
Segment 7
Incremental
Incremental
Combine
Percent
range, ppm
average*, ppm
segment, ppm
difference
Arsenic
0.25- 222.4
77.7
43.2
79.9
Chromium
5.0 - 108
44.1
30
47.0
Lead
244 - 830
476.6
486.5
-2.0
Titanium*5
7.1 - 42.8
20.1
13.7
46.7
Zinc
92 - 455
228
159
43.4
Segment 8
Incremental
Incremental
Combine
Percent
range, ppm
average®, ppm.
segment, ppm
difference
Arsenic
1,65- 39.2
19.7
19.1
3.1
Chromium
7.5 - 29
16.9
12.5
35.2
Lead
244 -830
476.6
456
4.5
Titanium6
5.7 - 18.3
13.2
30.1
-56.1
Zinc
86 -440
218.8
265
-17.4
a. Arithmetic mean based on 4 samples.
B. Titanium values are suspect. See text.
7.5.2.3 Processor - Sit® 3
Site 3 generally accepts all forms of wood waste except creosote- treated
woods. Workers at the facility nana pick wood from the dumping floor which
then goes through a picking station to further remove unwanted materials from
the fuel. Access to this site was very limited. As a result, only one
stockpile segment could be sampled.
Tables 7-17 through 7-19 present the limited results of the sampling at site
3. The results of the ultimate/proximate analysis appear consistent with
those from the other facilities. The one exception is the high chlorine value
of 0.16 percent dry weight, the highest value of all the processors. This
7-32
-------
Table 7-16. Processor Site 2 Toxic Characteristic Leachate Procedure (TCLP) in
laboratory ash. (heavy metals), ntg/1.
Metal
Average
value®
Maximum
Detection
limit
U.S. EPA
limit
Number of
samples
Arsenic
ND
ND
0.5
5
2
Barium
ND
ND
1
100
2
Cadmium
ND
ND
0,2
1
2
Chromium
7.65
11
0.2
5
2
Lead
ND
ND
2
5
2
Selenium
NO
ND
0.5
1
2
Silver
ND
ND
0.1
5
2
Mercury
ND
ND
O.l
0.2
2
a. Analyses below detection limit were assumed to be % the detection limit
for calculation purposes.
suggests the presence of PVC. plastics or treated/glued woods containing
chlorine. Also, sulfur and ash contents, when compared to facility averages,
are low, suggesting a fairly clean product.
No phenol compounds were detected above detection limits in the wood analyzed.
The detection limits, however, were the highest of all the facilities tested.
The minerals analysis of laboratory-prepared ash from this wood showed, average
levels of silicon dioxide and calcium oxide. These were the principal
components of the ash.
The metals analysis of the wood shows levels relative to and slightly lower
than the amount seen at other facilities. The composite sample for this site
measured the smallest amount of zinc detected for all the sites. However,
this site also measured the highest level of nickel {53 ppm) and the second
highest level of cadmium (1.7 ppm) of all the facilities tested.
The consistency of the fuel at this site is variable and can be seen in the
results of the incremental analyses. Also these samples were taken from a
small cross-section of the processed wood on site.
The results of the TCLP test on laboratory ash for this facility show failure
levels for chromium and a high level of arsenic leaching. This is somewhat
puzzling considering the reasonably low levels of arsenic and chromium found
in the wood.
7.5.2.4 Processor - Site 4
The primary product of site 4 is mulch for landscaping. The facility also
produces wood fuel as a secondary product. The facility refuses to accept
treated woods {creosote, CCA) but will accept some painted woods. Since the
facility's main product is mulch no effort is made to remove soil from the
wood. All samples taken from this site were from wood piles of a size grading
appropriate for wood fuel.
7-33
-------
fable 7-17, Summary data from Processor Site 3.
Wood ultimate analysis
Average
Standard
deviation
Minimum
Maximum
Number of
samples
As received
% moisture
5.19
-
-
-
1
Btu/lb
8339
-
-
-
1
Dry basis
% carbon
52,9
_
-
1
% hydrogen
5.85
-
-
-
1
% nitrogen
0.51
_
-
-
1
% sulfur
0.08
_
-
_
1
% ash
3.87
-
_
_
1
% oxygen (difference)
36.79
_
-
-
1
% chlorine
0.16
_
-
1
% volatile
78.52
_
-
-
1
% fixed carbon
17.61
_
-
-
1
Btu/lb
8795
-
-
-
1
Phenols in wood
Average
Standard
Minimum
Maximum
Number of
uo/g
deviation
pg/g
ug/g
samples
Phenol*
<2.64
—
1
Per.tachlorcphenol
<13.60
-
_
1
2-chlorophenol
<2.64
-
-
1
2-nitrophenol
<2.64
-
-
1
2,4-dimethylphenol
<2.64
-
_
1
2,4-diehlorcphenol
<2.64
_
_
1
4-chloro-3-methylphenol
<2.64
_
-
1
2,4,6-trichlorophenol
<2.64
-
1
2,4-dinitrophenol
<13.64
_
~
1
4-nitrophenol
<13.64
-
~
1
2»methyl~4,6-dinitrophenol
<13.64
-
~
1
Mineral analysis of laboratory ash.
Average
Standard
Minimum
Maximum
Number of
% by wt.
deviation
% by wt.
% by wt.
samples
Silicon dioxide
36.55
*
_
1
Aluminum oxide
7.14
-
-
1
Titanium dioxide
1-64
_
-
1
Iron oxide
4.78
• -
-
Calcium oxide
22.4
-
_
1
Magnesium oxide
3.92
-
-
1
Potassium oxide
5.6
-
-
-
Sodium oxide
4 . 62
-
-
_
1
Sulfur trioxide
9.46
-
-
1
Phosphorus pentoxide
2.04
_
-
_
1
Lead oxide
-
-
-
1
Zinc oxide
-
-
_
1
Manganese oxide
-
-
-
-
1
a. Analyses below detection limit were assumed to be % the detection limit
for calculation purposes.
7-34
-------
Table 7-18. Summary data from Processor Site 3 elemental metals analysis {ppm
in dry wood). Negative values represent detection limits,
Description
As
cr
Pb
Ti
Ztl
Ba
Cd
cu
Hg
Ml
AS
Increment
20,9
16.5
259.5
8.7
350
Increment.
53,3
15.5
105.6
18.65
250
Increment
112.9
35.5
88
13.68
88
Increment
1.66
-5
25
2.58
2
Combination
7.22
17
59.5
8.1
2.5
72.8
1.7
37
-0,25
53
0.075
Table 7-19, Processor Site 3 Toxic Characteristic Lsachate Procedure (TCLP) in
laboratory ash {heavy metals}, mg/1.
Metal
Average
value3
Detection
limit
U.S. EM
limit
Number of
samples
Arsenic
3.7
0.5
5
1
Barium
ND
1
100
1
Cadmium
ND
0.2
1
1
Chromium
20
0,2
5
1
Lead
ND
2
5
1
Selenium
ND
0.5
1
1
Silver
TO
0.1
5
1
Mercury
KD
0.1
0.2
1
a Jtaalyses below detection limit were assumed to be % the detection limit for
calculation purposes.
fable 7-20 through 7-23 present the results of the sampling at site 4. The
ultimate/proximate analyses indicate a high ash content of 16 percent dry
weight in the wood. This high ash, coupled with a moisture content of 20
percent, significantly lowers the value of this wood as a fuel {6033 Btu/lb).
The wood at this site is regularly wetted and mixed to promote decay. Mood
portions sold as fuel are the remains from this process.
Low sulfur and chlorine levels for this site suggested that the facility is
successful in either preventing or removing contaminants such as tarpapar and
PVC plastics from the waste stream.
Of the phenol compounds tested, only one sample showed the presence of
pentachlorophenol at 31 ppm. This one value suggests that some penta-treated
wood was delivered to the site and escaped detection. Wood piles are not
mixed together at the site but are instead kept separate to keep track of
aging.
The results of the two minerals analyses are remarkably alike, with no
significant variation between the samples. The principal component of the ash
7-35
-------
Table 7-20. Processor Site 4.
Wood ultimate analysis
Average
Standard
deviation
Minimum
Maximum
Number of
samples
Is received
% moisture
20.01
2,87
15.96
22.63
4
Btu/lb
6033
406.23
5440
6362
4
Dry basis
% carbon
45.38
3.23
42.04
49.19
4
% hydrogen
5.17
0.71
4.17
5.79
4
% nitrogen
0.73
0.12
0.58
0.83
% sulfur
0.05
0.03
0.02
0.08
4
% ash
15.99
11.21
5.61
31.26
4
% oxygen (difference)
32.69
7.70
21.64
38.31
4
% chlorine
0.06
0.00
o.os
0.06
% volatile
68.47
7.80
59.47
76.49
4
% fixed carbon
15.55
4.24
9.27
18.31
Btu/lb
7542.75
460.57
7031
8076
4
Phenols in wood
Average
Standard
Minimum
Maximum
Number of
pg/g
deviation
pg/g
pg/g
samples
Phenol®
<1.74
—
<0.99
<2.64
4
Pentachlorophenol
10.51
13.70
2.55
31.00
4
2-chlorophenol
<1.74
-
<0.99
<2.64
4
2-nitrophenol
<1.74
-
<0.99
<2.64
4
2,4-dimethylphenol
<1.74
_
<0.99
<2.64
4
2,4-dichlorophenol
<1.74
-
<0.99
<2.64
4
4-chloro-3-methylphenol
<1.74
-
<0.99
<2.64
4
2,4,6-trichlorophenol
<1.74
<0.99
<2.64
4
2,4-dinitrophenol
<8 .92
-
<5.10
<13-60
4
4-nitrophenol
<8.92
-
<5.10
<13.60
4
2-methyl-4,6-dinitrophenol
<8 . 92
-
<5.10
<13,SO
4
Mineral analysis of laboratory ash
Average
Standard
Minimum
Maximum
Number of
% by wt.
deviation
% by wt.
% by wt.
samples .
Silicon dioxide
64.32
0.20
64.18
64.46
2
Aluminum oxide
10.86
0.48
10.52
11.20
2
Titanium dioxide
0.63
0.04
0.60
0.66
2
Iron oxide
€.13
0.33
5.39
6.36
2
Calcium oxide
6.46
O.Oi
6.40
6.51
2
Magnesium oxide
2.54
0.08
2.48
2 . 60
2
Potassium oxide
3.47
0.09
3.40
3.53
2
Sodium oxide
2.38
0. 00
2.38
2.38
2
Sulfur trioxide
0.71
0.16
0.60
Q.82
2
Phosphorus pentoxide
1.00
0.00
1.00
1.00
2
Lead oxide
0 .24
0.04
0.21
0.26
2
Zinc oxide
-
-
_
-
_
Manganese oxide
-
-
-
-
-
a. Analyses b¥low"detection" limit' were assumed to' be 14 the detection limit for-
calculation purposes.
7-36
-------
Table 7-21. Summary data from Processor Site 4.
Total metals analysis, ppa in dry wood.
Metal
Number
Arithmetic
Stamndard
Minim*
90th
as1"
HMCilMM#
Median
upper
Geometric
Lognormal
of
average
deviation
detected*
percen-
percen-
detected
confidence
mean
MVU mearf
sanples
tile
tile
median''
Arsenic
8
6.95
4,87
1.11
15.1
15.7
15.7
6.4
f .74
5.02
7,56
Chromium
8
1.13
6.59
5
23 .5
23.5
23.5
12.75
16.97
11.49
13.30
Lead
8
93.50
41.09
43
159 .5
159.5
159.5
96.75
116.S3
85.23
93,86
Titanium'1
8
37.44
15.74
16.9
69 , 6
69.6
69.6
38.45
46.14
34.65
37.51
Ti taniunf
8
530.5
208.4
3S8
663
663
663
-
¦ _
-
-
Zinc
8
129.38
46.20
R0
21S
215
215
126,5
155.15
122.50
129.31
Bar ium
«
75.94
22.63
33 , 5
107
107
107
77
91.02
72.26
76.47
Cadmium
8
0.41
0.23
0 .25
0,75
0.75
ft.75
0.25
G .52
0.36
0.41
Copper
ft
15.69
8.11
6
31
31
31
15.75
20,12
13 .79
15.82
Mercury
8
0,125
-
0.125
0.125
0.125
0.125
0.125
0.125
0.125
0.125
Mickel
8
13.00
8.34
2.5
26
26
26
12.75
18.05
9 .84
13 .90
Silver
8
0.108
0.09
0.025
0.3
0.3
0.3
0.075
0.14
0 .09
0. U
Five metals analysis, ppro in dry wood.
Metal
Number
Arithmetic
Starj.dard
Minimum
90"
85"
Maximum
Median
Upper
Geometric
Lognoraal
of
average
deviation
detected*
percen-
percen-
detected
confidence
mean
MVU Bean'
samples
tile
tile
median6
Ar senic
15
7.75
9. 58
0.28
14.9
37.4
37.4
5.7
7.29
3 . 58
9.09
chromium
15
15.83
10.43
2.5
30.5
32
• 32'
16
18.25
11.51
17.23
Lead
15
119.77
81.01
29
237.5
286
286
110.5
135.91
94.23
121.89
Ti t snium,J
15
43.73
43.58
10. S
76.6
176.5
176.5
27
46.32
30. 97
42.22
2 inc
15
200.47
276.28
S3
210
1180
1180
132
198.94
138.29
178.24
a. In cases where samples registered below the detection limit, one-half of the detection limit was used,
b. Level for which there is 95% confidence that the median of any similar random sampling will show a lower
value,
c. The Minimum Variance Unbiased {MOT} estimator of the true median for a lognormal distribution {Gilbert,
1907) .
d. Values are suspect, see text in section 7.4.
e. Calculated from minerals analysis.
f. Meaningless, since most of the data are below detection limit.
-------
Table 7-22. Processor Site 4 average incremental vs. Composite metals analysis.
Segment 1
Incremental
Incremental
Combine
Percent
range, ppm
average4, ppm
segment, ppm
difference
Arsenic
0,28- 37.4
9.7
1.115
770
Chromium
2.5 - 23,5
8.3
5
66.0
Lead
29 - 63
41.875
43
-2.6
Titanium6
11.5 - 17.2
14.5
22.1
-34.4
Zinc
63 -120
80', 3
95
-15.5
Segment 2
Incremental
Incremental
Combine
Percent
range, ppm
average8, ppm
segment, ppm
difference
Arsenic
2.47- 12,1
5.98
8.3
-28.0
Chromium
16 - 27
20,4
17.5
16.6
Lead
110,5 - 180.5
140.3
159.5
-12.0
Titanium"
23.1 - 176.5
79.9
16.9
372.8
Zinc
169 -1180
427,5
215
98.8
Segment 7
Incremental
Incremental
Combine
Percent
range, ppm
average4, ppm
segment, ppm
difference
Arsenic
6.9- 14.9
11.3
7.1
59.2
Chromium
10 - 32
24.4
18.5
31.9
Lead
107.5-286
213
128
66.4
Titanium15
32.8- 76,6
55
37.1
48.2
Zinc
81 -210
146.8
154
-4.7
Segment 8
Incremental
Incremental
Combine
Percent
range, ppm
average*, ppm
segment, ppm
difference
Arsenic
0.77- 5.7
2,73
15.7
-82.6
Chromium
5 - 11.5
8.5
14.5
-41.4
Lead
44.5 -114,5
72
110
-34.5
Titanium15
10.5 - 27
19.5
39.8
-51.0
Zinc
S3 -132
96.3
158
-39.1
a. Arithmetic mean based on. 4 samples.
B. Titanium values are suspect. See text.
is silicon at a level of 64 percent. This strongly suggests that the bulk of
the high ash content is the result of soil mixed in the wood,
Metal analysis at this site indicated a very low variance between sample
values. This is even true with the incremental analysis. Upon further
examination, the composite data from this site is seen to follow a normal
rather than lognormal distribution. The medians and arithmetic averages are
almost identical for each metal including most of the incremental analysis.
This case demonstrates very well how compositing samples will most accurately
characterize bulky waste. Over the months the wood piles are allowed to
decompose they are repeatedly mixed. This compositing results in the normal
distribution seen in even the incremental samples.
7-38
-------
When compared to the median values for all six facilities, the metals content
in this facility's wood is somewhat lower in all cases except titanium.
However, considering the unusually high ash content of this wood, the lb/MMBtu
of metals emissions from a boiler could be somewhat higher even though the
metals concentrations in ash will be very dilute.
Using representative values from the analysis of CCA treated wood, estimates
of CCA contamination were calculated for this site. Assuming that 100
percent of the chromium, copper, and arsenic found, in this fuel is the result
of CCA treated wood, the wood from this facility ranges from 0.1 percent to
2,9 percent CCA. and averages 0.8 percent, lowest of all the sites and
indicative that CCA can adequately be removed from the waste fuel stream if
the processors desires to do so.
The results of the TCLP tests on laboratory ash show some leaching of barium,
chromium, and silver, but none of these exceed regulatory levels.
Table 7-23. Processor Site 4 Toxic Characteristic Leachate Procedure (TCLP) in
laboratory ash (heavy metals), mg/1.
Metal
Average
value3
Maximum
Detection
limit
U.S. EPA
limit
Number of
samples
Arsenic
ND
ND
0.5
5
2
Barium
0.8
1.1
1
100
2
Cadmium
ND
ND
0.2
1
2
Chromium
1.1
1.4
0.2
5
2
Lead
W3
ND
2
5
2
Selenium
ND
ND
0.5
1
2
Silver
0.13
0.2
0.1
5
2
Mercury
ND
ND
0.1
0.2
2
a Analyses below detection limit were assumed to be % the detection limit
for calculation purposes.
7.5.2.5 Processor - Site f
Site 6 accepts all forms of wood waste,- however, treated woods are sorted out
before processing the wood into a fuel product. The fuel is processed using a
shaker screen, float tank, picking station, and trommel screen. Samples were
collected from cross sections of all of the available processed wood fuel and
from both process lines.
Tables 24 through 27 present the results of the sampling at site 6. The
results of the ultimate/proximate analysis are similar
to those of the other sites and vary little except for moisture and ash
content. Moisture content ranged between 15.9 and 35.2 weight percent,
averaging 23.75 percent while ash content ranged between 2.94 and 8.58 dry
weight percent. The ash content is somewhat lower than the average of the
facilities but is still much higher than clean wood, which indicates the
presence of non-wood contaminants in the fuel. Percent sulfur varied over a
broader range than seen at other sites and averaged at 0.15 percent, the
highest average sulfur content of all the sites visited. This suggests the
7-39
-------
Table 7-24. Processor Site 6.
Wood ultimate analysis
Average
Standard
deviation
Minimum
Maximum
Number of
samples
to received
% moisture
23.75
8.15
IS. 31
35,21
4
Btu/lb
6375
756
5346
7162
4
Dry basis
% carbon
50,11
0.82
48.93
50,81
4
% hydrogen
5.87
0.17
5.71
6.08
4
% nitrogen
0.52
0.08
0.42
0.59
4
% sulfur
0,15
0.07
0.10
0.24
4
% ash
5.15
2.41
2.94
8.58
4
% oxygen (difference)
38.20
1.75
35.95
40.11
4
% chlorine
0.03
0.01
0.02
0,04
4
% volatile
78.53
1.72
76.37
80.35
4
% fixed carbon
16.33
1.04
15.05
17.50
4
Btu/lb
8352
131
8243
8517
4
Phenols in wood
Average
Standard
Minimum
Maximum
Number of
us/g
deviation
w/g
pg/g
samples
Phenol3
<1.56
_
<0.99
<2.64
4
Pentachlorophenol
<8.08
<5.10
<13,6
4
2-chlorophenol
<1.56
<0.99
<2.64
4
2-nitrophenol
<1.56
-
<0.99
<2,64
4
2, 4-dimethylphenol
<1.56
_
<0.99
<2.64
4
2, 4-dichiorophenol
<1.56
-
<0.99
<2.64
4
4-chloro-3-methylphenol
<1.56
-
<0.99
<2.64
4
2,4,6-trichlorophenol
<1-56
_
<0,99
<2.64
4
2,4-dinitrophenol
<8.08
-
<5,10
<13.6
4
4-nitrophenol
<8.08
_
<5.10
<13.6
4
2-methyl-4,6-dinitrophenol
<8.08
-
<5,10
<13.6
4
Mineral analysis of laboratory ash.
Average
Standard
Minimum
Maximum
Number of
% by wt.
deviati on
% by wt,
% by wt.
samples
Silicon dioxide
52.67
1.22
51.80
53.53
2
Aluminum oxide
10.76
0,34
10.52
11.00
2
Titanium dioxide
1.78
0.11
1,70
1.86
2
Iron oxide
6.69
0.16
6.58
6.80
2
Calcium oxide
11.00
0,85
10.40
11.60
2
Magnesium oxide
2.91
0.13
2.82
3.00
2
Potassium oxide
2.67
0.09
2.60
2.73
2
Sodium oxide
2.57
0.18
2.44
2.70
2
Sulfur trioxide
7,05
0.26
6.86
7.23
2
Phosphorus pentoxide
0.60
0,00
0.60
0,60
2
Lead oxide
0,36
0,18
0.23
0.48
2
Zinc oxide
-
-
-
-
Manganese oxide
-
-
-
-
-
a. "Analyses below detection limit were assumed to be % the detection limit for
calculation purposes,
7-40
-------
fable 7-25. Summary data from Processor Site 6.
Total metals analysis, ppm in dry wood.
Metal
Number
of
samples
Arithmetic
average
Stanndard
deviation
Hiniiun
detected"
90 estimator of the true median for a lognormal distribution {Gilbert,
1987).
d. Values are suspect, see text in section 7.4.
e. Calculated from minerals analysis.
f. Meaningless, since most of the data are below detection limit.
-------
Table 7-26. Processor Site 6 average incremental versus composite metals analysis.
Segment 1
Incremental
Incremental
Combine
Percent
range, ppm
average®, ppm
segment, ppm
difference
Arsenic
0.67- 1.26
1.00
0.8
25.0
Chromium
5 - 10
5.4
6.25
-13.6
Lead
43.5 -260.5
132.9
84.5
57.3
Titanium"
34.8 -196
110
30.7
258.3
Zinc
63 -204
125.6
97.5
28.8
Segment 2
Incremental
Incremental
Combine
Percent
range, ppm
average®, ppm
segment, ppm
difference
Arsenic
0.6- 6.93
2.71
7.3
-62.9
Chromium
5.5- 6.5
6
6.5
-7.7
Lead
68,5-104
90.6
108
-16.1
Titanium"
23.3- 38.4
30.5
14
117.9
Zinc
82 -101
93.8
100
-6.2
Segment 7
Incremental-
Incremental
Combine
Percent
range , ppm
average*, ppm
segment, ppm
difference
Arsenic
1.87- 9.79
5.78
20
-71.1
Chromium
7.5 - 19
13.6
22.5
-39.6
Lead
27 -378
127
148
-14.2
Titanium0
23.3 -100.6
44.3
14.4
207.6
Zinc
48 -345
138
160
-13.8
Segment 8
Incremental
Incremental
Combine
Percent
range, ppm
average*, ppm
segment, ppm
difference
Arsenic
0.25- 0.75
0.4
5.8
-93.1
Chromium
5-7
5
13
-61.5
Lead
68 -329.5
191.5
190.5
0.5
Titanium0
13.3 - 80.2
49.6
41
21.0
Zinc
152 -420
260
260
-0.1
a. Arithmetic mean based on 4 samples.
B. Titanium values are suspect. See text.
presence of sulfur-containing materials such as asphalt, telephone poles,
railroad ties, tarpaper, or wallboard.
Very little chlorine was detected in the sampled wood, suggesting adequate
removal of PVC plastics and relatively little processing of chlorine-
containing wood types. Observing the processor operation, it was noted that
the float tanks removed all the plastics seen entering the system.All the
phenols compounds tested were below detection limits and therefore the
presence of phenol contaminants was minimal.
The results of the minerals analyses show that the two principal components of
the ash are silicon dioxide and calcium oxide. This is consistent with most
of the data from the other facilities. This bulk ash mixture is
7-42
-------
characteristic of wood fuel in general with the high silicon mainly attributed
to soil mixed in the wood.
Metals analysis at this site indicated similar results to those of site 4.
Distribution, curves of the data from the composite samples indicate a normal
distribution in most cases with a few outliers. The results of the
incremental analysis still follow the predicted lognormal distribution but to
a lesser extent. Mercury was not detected above detection limits and the
cadmium and the silver levels, when detected, were very low. Median and
arithmetic averages for each of the metals tested except titanium and nickel
were below the median and average of all the processors. Nickel values, when
detected, were somewhat higher than most of the other facilities (not the
highest|.
This facility had two separate process lines. Comparing the ultimate analyses
of samples from segment 7 and segment 8 {process line 1 and process line 2)
the most obvious difference is the ash content.
Table 7-27. Processor Site 6 Toxic Characteristic Leachate Procedure (TCLP) in
laboratory ash {heavy metals}, rag/1.
Metal
Average
value®
Maximum
Detection
limit
U.S. EPA
limit
Number of
samples
Arsenic
ID
ND
0,5
5
2
Barium
ND
ND
1
100
2
Cadmium
ND
ND
0,2
1
2
Chromium
1.15
1.2
0.2
5
2
Lead
ND
NO
2
5
2
Selenium
ND
ND
0.5
1
2
Silver
ND
ND
0.1
5
2
Mercury
ND
ND
0.1
0.2
2
a Analyses below detection limit were assumed to be % the detection limit
for calculation purposes.
Process line 1 without a trommel has a much higher ash content than process
line 2 which has a trommel. Percent' ash values were 8.58 dry weight percent
for line 1 and 2.94 dry weight percent for line 2. Another difference in the
samples taken from the process lines is the results of the metals analyses.
Process line 1 has much higher levels of arsenic, chromium, copper, and nickel
than line 2 which suggests that process line 1, which deals with smaller sized
wood waste, is seeing larger amounts of CCA treated woods. Even so, the
calculated CCA contamination for the entire site ranged only from 0.2 to 2.9
percent CCA treated wood, averaging 0.9 percent.
The results of the TCLP tests on laboratory ash for this facility indicate
some leaching of chromium within regulatory limits. The average leachate
level for chromium was 1.15 mg/L and the regulatory level is 5 mg/L.
7.5.2.6 Processor - Site 7
7-43
-------
Site 7 accepts and processes mostly construction wood waste and some
demolition wood into hogged wood. Some manual effort is made to remove non-
wood contaminants, and loads that are too contaminated are rejected. Conveyor
samples could not be taken at this site and the amounts of processed wood were
limited. Two of the eight samples are cross section combinations of the other
segments.
Tables 7-28 through 7-31 present the results of the sampling at site 7. The
ultimate/proximate analysis at this site is consistent with that at the other
sites. The moisture content of this wood is very low, averaging about 5.4
weight percent. Visual inspection confirms that very little of this wood is
"clean* unprocessed wood. Ash concentrations vary dramatically from. 0.24
percent to 12.58 percent dry weight, averaging 6.4 percent.
Average sulfur content is fairly high at 0,1 percent suggesting that
contaminants such as asphalt and tarpaper are present. Visual inspection of
the samples confirmed these contaminants. Average chlorine levels of 0,05
percent suggest some contamination of chlorine-containing material. Visual
inspection indicated the presence of plastics ana particle board mixed with
the processed wood.
The results of the minerals analysis show very low levels of silicon dioxide
in the laboratory wood ash compared to previous results which strongly
suggests that the nonwood components of the processed wood at this site are
the result of paints or treatments on the wood rather than1 soil contamination.
To evaluate the accuracy of these results, metals analysis on composite .
samples was performed at a different test, laboratory using different methods
than the analysis of the other sites. With the exception of titanium, these
results are similar to those of the other facilities. Incremental analysis
was still performed using the previous laboratory and these results were
consistent with the work of the new laboratory.
The consistently high levels of titanium suggest that the waste wood stream
contained a lot of painted wood. The lower levels off lead than those seen at
other sites suggest that only a small portion of the painted wood is
contaminated with lead-based paints. These results, coupled with very low
moisture content of the wood, suggest that most of the wood collected by this
site comes from manufacturing and construction sources rather than demolition
and land-clearing sources.
Most of the metals concentrations are significantly lower than those at other
sites, especially lead, zinc and barium. Since this facility basically does
not remove contaminated materials from the waste stream, it would appear that
this facility is controlling its waste wood fuel, quality by limiting the type
of waste wood it receives.
Assuming 100 percent of the arsenic, chromium, and copper present in the wood
is the result of CCA treatment, the estimated level of CCA treated wood at
this site was calculated. The resulting values range from 0.2 to 8,0 percent
CCA wood and averaged 1.0 percent.
The results of the TCLP tests on laboratory ash for this facility show failure
for chromium. Chromium levels in the leachate were 12 mg/L and 6.2 mg/L while
the USEPA regulatory level is 5 mg/L.
7,5.2,? Combination of Six Processors
7-44
-------
Table 7-28. Processor Site 7,
Wood ultimate analysis
Average
Standard
deviation
Minimum
Maximum
Number of
samples
As received
% moisture
5.37
0.30
5.06
5.75
4
Btu/lb
7934
263
7620
8244
4
Dry basis
% carbon
50.45
2 -31
47.26
52.52
4
% hydrogen
5.86
0.18
5.62
6.03
4
% nitrogen
0.62
0.04
0.59
0. 68
4
% sulfur
0.1
0.03
0.06
0.14
4
% ash
6.4
5.28
0.24
12.58
4
% oxygen {difference)
36.57
3
33.79
40.54
4
% chlorine
0.05
0.01
0.04
0.05
4
% volatile
77.24
2.82
73.26
79.24
4
% fixed carbon
16.36
6.41
8.18
22.29
4
Btu/lb
8437
289.25
8040
8718
4
Phenols in wood
Average
Standard
Minimum.
Maximum
Number of
nsr/o
deviation
usr/s
ug/g
samples
Phenol*
<1.98
_
<1.65
<2.31
4
Pentachlor©phenol
<10.20
_
<8.50
<11.90
4
2-chloropheno1
<1.98
_
<1.65
<2-31
4
2-nitrophenol
<1.98
-
<1.65
<2.31
4
2,4-dimet.hylphenol
<1.98
_
<1.65
<2.31
4
2,4-dichiorophenol
<1.98
-
<1,65
<2.31
4
4-chloro-3-roethylphenol
<1.98
-
<1.65
<2.31
4
2,4,6-trichlorophenol
<1.98
<1.65
<2.31
4
2,4-dinitroph®nol
<10.20
_
<8.50
<11.90
4
4-nitrophenol
,10.20
_
<8.50
<11.90
4
2-methyl-4,6-dinitrophenol
<10.20
-
<8.50
<11.90
4
Mineral analysis of laboratory ash.
Average
Standard
Minimum
Maximum
Number of
% by wt.
deviation
% by wt.
% by wt.
samples
Silicon dioxide
29.46
4.12
26.54
32.37
2
Aluminum oxide
4.42
0.13
4.32
4.51
2
Titanium dioxide
0.91
0.04
0.88
0.94
2
Iron oxide
4.99
1.85
3.68
6. 29
2
Calcium oxide
32.84
3.34
30.48
35.2
2
Magnesium oxide
6.34
0.37
6.08
6.6
2
Potassium oxide
4.55
0.07
4.5
4.6
2
Sodium oxide
3.25
0.18
3.12
3.38
2
Sulfur trioxide
5.46
1.01
4.74
6.17
2
Phosphorus pentoxide
0.6
0
0.6
0.6
2
Lead oxide
-
-
-
_
Zinc oxide
_
_
-
_
Manganese oxide
-
-
-
-
-
a. Analyses below detection limit were assumed to be % the detection limit for
calculation purposes.
7-45
-------
Table 7-29. Summary data from Processor Site 7,
total metals analysis, ppan in dry wood.
Metal
Number
Arithmetic
Stanndard
Mininrun
90"
85"
Maximum
Median
Upper
Seonwtrie
Lognormal
of
average
deviation
detected®
percMi-
p»rc«n-
dotactod
confidence
mean
MOT BUD'
sainpiss
til#
fcila
median*
Arsenic
8
4.75
1. S3
1
6
6
6
5.5
6.39
4.2
4.97
Chromium
8
15.4
3 , 62
11,5
21.8
21.8
21 §
14.7
169.76
15.05
838.13
Lead
8
50.3
15.72
22.9
67.5
67.5
67.5
51.3
61.13
47. €6
50.61
Titanium'1
8
342.4
49.57
307.2
460. R
460.8
460.8
323.2
370.46
339.71
342.20
Tiranium*
2
3 53
176.9
226
480
480
480
-
¦ _
. -
Zinc
8
59.8
19.61
41.0
93 .2
93.2
§3.2
SI. 2
70.50
57.26
59.72
Barium
8
50.3
27.18
15
97
97
97
50. S
65.44
43.21
50. S6
Cadmium
8
0.90
0.81
0.38
1.6
1.6
1.6
0.736
1.15
0.78
0. 90
Copper
8
22.5
25.34
9.4
84.7
84.7
84.7
14.2
26. 68
16.68
20.58
Mercury
8
0.073
0.026
0.04
©.1
0.1
0.1
0.075
0.088
0 .068
0.073
Nickel
8
4.2
0.65
3.2
5.12
5.12
5.12
4.416
4.66
4.19
4.23
Silver
8
0.113
0. 04
0.1
0.2
0.2
0.2
0.1
0.13
0.11
0.11
Five metals analysis, ppm in dry wood
Metal
Nurebar
Arithnatic
Staumdart
Mini mun:
90a
85;*
Maximum
Median
Upper
Geometric
Lognormal
of
avarage
deviation
detected3
percen-
percen-
detected
confidanca
mean
MTO mean5
samples
tile
tile
median"
Arsenic
16
8.30
11.28
0.41
27
39.2
39.2
3 .875
6.99
3.72
8.16
ChroatluM
16
10. 63
9.01
2.5
28
31,5
31. 5
8.75
11.44
7. Si
10,75
i#a
-------
fable 7-30. Processor Site 7 average incremental versus composite metals analysis.
Segment 1
Incremental
Incremental
Combine
Percent
range, ppm
average", ppm
segment, ppm
difference
Arsenic
1 - 5.21
2.2725
5
-54.6
Chromium
5 -11.5
5.5
14.1
-61.0
Lead
23 -64
41.375
46.464
-11.0
Titanium6
6,77-15.24
12.535
460.8
-97.3
Zinc
31.5 -45
38.5
43.52
-11.5
Segment .2
Incremental
Incremental
Combine
Percent
range, ppm
average*, ppm
segment, ppm
difference
Arsenic
1.08-39.2
11.8175
6
97.0
Chromium
5 -28
11.625
17.6
-33.9
Lead
6.5 -42.5
23.75
67.52
-64.9
Titanium"
3,87-19.48
8.985
320
-97.2
Zinc
18.5 -40.5
30.625
71.04
-56.9
Segment 7
Incremental
Incremental
Combine
Percent
range, ppm
average®, ppm
segment, ppm
difference
Arsenic
0.41-27
8.185
6
36.4
Chromium
5 -31.5
11.25
18.5
-39.2
Lead
23 -43.5
28.375
51.392
-44.8
Titanium6
3.5 -14.99
8.9075
320
-97.2
Zinc
18 -29
24.625
51.2
-51.9
Segment 8
Incremental
Incremental
Combine
Percent
range, ppm
average4, ppm
segment, ppm
difference
Arsenic
4.15- 20.2
10.925
5
118.5
Chromium
10.5 - 18
14.125
12.5
13.0
Lead
35 -123.5
63 .375
64
-1.0
Titanium"
21.46- 37.68
26 . 605
326.4
-91.8
Zinc
44.5 - 88
58 . 5
45.696
28.0
a. Arithmetic mean based on 4 samples.
B, Titanium values are suspect. See text.
Tables 7-32 through 7-34 summarize results of the sampling at all six
processor sites. The following subsections discuss these results, variations
in the data, and conclusions that can be made of processed wood as a whole.
7.5.2.7.1 Ultimatc/Proxlaiat* Analysis
A total of 21 composite samples from six processors were analyzed for
ultimate/proximate properties. Reviewing the data as a whole, four of these
results vary the most, tha weight percent analyses of moisture, sulfur, ash,
and chlorine found in the wood. The other results do not vary significantly.
The overall heating value for this wood averaged 8260 Btu/lb dry wood which is
somewhat lower than typical values available in the literature and nay be
7-47
-------
Table 7-31. Processor Site 1 Toxic Characteristic Leachate Procedure (TCLP) in
laboratory ash {heavy metals), mg/1.
Metal
Average
value®
Maximum
Detection
limit
U.S. EPA
limit
Number of
samples
Arsenic
TO
ND
0.5
5
2
Barium
ND
ND
1
100
2
Cadmium
ND
ND
0.2
1
2
Chromium
9.1
12
0.2
5
2
Lead
ND
ND
2
5
2
Selenium
ND
ND
0.5
1
2
Silver
ND
ND
0.1
5
2
Mercury
ND
ND
0.1
0.2
2
a Analyses below detection limit iters assumed to be % the detection limit for
calculation purposes.
attributed to the higher ash content in processed waste wood compared to
"clean" wood.
Moisture and ash concentrations varied the most in this program. Moisture is
not normally an environmental concern but is important for maintaining stable
operating conditions in a boiler. Moisture content varies too much even in
pure wood products tc be used as anything but a general indicator as to the
source and -quality of the fuel. In general, high moisture contents indicate
larger siIvicultural portions in waste fuel, while low moisture may indicate
larger portions of construction and processed woods.
High ash contents indicate contamination of the wood from two sources. Tha
primary source of ash seems to be the inclusion of dirt in the wood
characterized by high levels of silicon in the ash. Ash of this sort is not
too environmentally important except for the possibility of over-taxing
particulate control devices and increasing particulate emissions. Screening
the waste wood product during various processing stages significantly limits
dirt from the final product. Another source of ash is the inclusion of
nonwood materials such as asphalt, tarpaper, insulation, and metals as well as
a variety of paints and coatings. This source of ash is the most important
environmentally. Ferrous metals in the form of nails, staples, or fixtures
are fairly easy to remove with magnetic separators and constitute a valuable
by-product of scrap metal. Metals, tar paper, insulation and plastics can be
removed from wood quite easily using float tanks. As observed during the site
visits, when float tanks and metals removal systems were properly functioning
there was very little solid contamination in the waste wood product.
However, the removal of "treated" woods is more difficult and is best
accomplished by limiting the type of wood a facility will accept. Otherwise,
if a facility accepts all types of wood, the wood product quality is
controlled by the types of "treated" woods hand picked from the fuel stream.
This requires a high level of attention and control in inspecting and
enforcing the manual picking operations.
Asphalt and tarpaper or shingles contamination can be inferred somewhat from
sulfur concentrations in the fuel. Unfortunately certain wood types such as
7-48
-------
Table 7-32, Combination of six processors.
Wood ultimate analysis
Average
Standard
deviation
Minimum
Maximum
Number of
samples
As received
% moisture
17.08
8.02
5.06
35.21
21
Btu/lb
6858
839
5346
8333
21
Dry basis
% carbon
49.52
2.86
42.04
52.9
21
% hydrogen
5.76
0.44
4.17
6.2
21
% nitrogen
0,57
0.12
0.36
0.83
21
% sulfur
0.094
0.049
0.02
0.24
21
% ash
7.82
7.45
0.24
31.26
21
% oxygen (difference)
36.24
4.69
21.64
40.54
21
% chlorine
0.054
0.033
0.02
0.16
21
% volatile
76.95
5.S8
59.47
82.51
21
% fixed carbon
15.23
4.49
1.03
22.29
21
Btu/lb
8261
453.7
7031
8795
21
Phenols in wood
Average
Standard
Minimum "
Maximum
Number of
ug/g
deviation
ug/g
ug/g
samples
Phenol.®
0.87
0.34
0.33
1.60
22
Pentachlorophenol
8. §3
11. €9
0.85
43.00
22
2-chlorophenol
<1.47
_
<0-33
<2.64
22
2-nitropher.ol
<1.47
-
<0.33
<2.64
22
2;4-dimethylphenol
<1.47
_
<0.33
<2.64
22
2,4-dichlorophenol
<1.47
<0.33
<2.64
22
4-chloro-3-methylphenol
<1.47
_
<0.33
<2.64
22
2,4,6-trichlorophenol
<1.47
_
<0.33
<2.64
22
2,4-dinitrophenol
<7.572
-
<1.7
<13 .6
22
4-nitrophenol
<7.572
<1.7
<13.6
22
2-methyl-4,6-dinitrophenol
<7.572
-
<1.7
<13.6
22
Mineral analysis of laboratory ash.
Average
Standard
Minimum
Maximum
Number of
% by wt.
deviation
% by wt.
% by wt.
samples
Silicon dioxide
48.33
14.22
26.54
65.47
12
Aluminum oxide
8.55
2.48
4.32
11.2
12
Titanium, dioxide
1.19
0.45
0.6
1.86
12
Iron oxide
6.44
1.66
3.68
9.83
12
Calcium oxide
15.32
9.79
6.4
35.2
12
Magnesium oxide
3.53
1.74
1.24
6.6
12
Potassium oxide
3.61
0.93
2.6
5.6
12
Sodium oxide
2.94
0.75
2.27
4.62
12
Sulfur trioxide
5.76
3.14
0.6
9.96
12
Phosphorus pentoxide
0,84
0.46
0.35
2.04
12
Lead oxide
0.51
0.47
0.21
1.71
9
Zinc oxide
0.68
0.18
0.52
0 . 88
3
Manganese oxide
0.28
-
0.28
0.28
2
a. Analyses below detection limit were assumed to be % the detection limit
for calculation purposes.
7-49
-------
Table 7-33. Summary data from six wood processors.
Total metals analysis, ppm in dry wood.
Metal
Nwber
Arithmetic
Stanndard
Minimum
90,K
85"
Maximum
Kodian
Upper
Geometric
LognorMl
of
average
deviation
detected'1
percen-
pereen-
detected
confidence
no ait
KVU Man'
samples
tile
til®
median"
Arsenic
41
33.13
5 3.66
0.46
105.00
142.40
262.50
7.30
17.96
11.36
35.43
Chromium
41
38.46
50.91
2.5S
91.25
106.00
233.00
17.60
29.49
21.76
36.15
Lead
41
218.93
238.88
22.91
486.50
575.50
1300.00
127.00
186.00
140.91
215.54
Titanium11
41
93.61
129.00
8.10
320.CO
332.80
460,R0
32.60
61. 28
43.20
94.42
Ti tanlam"
12
444.92
249.96
132.00
663.00
1066.00
1066.00
391.50
S2b.63
386.81
446.83
Zinc
41
155.94
130.76
2.50
260.00
340.00
ROO.OO
134.00
152.15
117.23
170.60
Barium
41
151.79
162.16
15.00
450.00
55G.00
630.00
K7 .00
128.36
97.39
148.28
Cadmium
41
0.86
0. 56
0.25
1.60
1.60
2.00
0.70
0.84
0 . 67
44.26
Copper
41
109.14
511.40
4.00
65.50
84.67
3300.00
22.00
33 .99
24.48
Id)
Mercury
41
0.10
0.C4
0.03
0.13
0.13
0 . 13
0.13
-------
Table 7-34, Combination of six processors Toxic Characteristic Leachate Procedure
(TCLP) in laboratory ash {heavy metals), mg/1.
Metal
Average
value®
Maximum
Detection
limit
U.S. EPA
limit
Number of
samples
Arsenic
0.532
0.5
0.5
5
12
Barium
0.55
1.1
1
100
12
Cadmium
0.1
0.1
0.2
1
12
Chromium
"12.5?
46
0.2
5
12
Lead
2.083
14
2
5
12
Selenium
0.25
0.25
0.5
1
12
Silver
0.0625
0.2
0.1
5
12
Mercury
0.05
0.05
0.1
0.2
12
a Analyses below detection limit were assumed to be % the detection limit for
calculation purposes.
telephone poles and railroad ties contain high levels of sulfur as well.
Visually those sites using float tanks showed no sign of asphalt or tarpaper
in the product. Many of these sites also process telephone poles which
increase the sulfur content of the waste wood. Of all the sites the lowest
levels of sulfur were found at site 4. This sit® refuses any shipments
containing either asphalt or creosote- treated woods.
High chlorine values in wood fuel have been thought to be the result of PVC
plastics in the wood waste. However, from the analysis of pure woods,
telephone poles and woods using resins as binding agents also contain higher
levels of chlorine. These waste wood types in addition to PVC would be a
major source of chlorine contaminants. Chlorine values ranged from 0,02
percent to 0.16 percent dry weight but averaged, only 0.054 percent.
Figures 7-5 through 7-8 represent histograms of the data from all the
facilities for moisture, ash, sulfur, and chlorine. Moisture content did not
follow a distribution curve. Ash and chlorine levels both follow a distinctly
lognormal curve. Sulfur values almost conform to a normal distribution except
for one outlying value of 0.24 percent dry weight.
7.5.2.7.2 Phenols Analysis
In this project the only phenol compounds detected were phenol and
pentachlorophenol. The detected values were at very low levels, the maximums
being 1.6 ppm phenol and 43 ppm pentachlorophenol, The phenols tests were
included in the study to determine;
• if any of the wood types which have phenols derivatives such as
plywoods, or pentantachloroph«nol treated wood have leachable
organics; and
• as an indicator of pesticides, herbicides or other chlorinated
organics which could be present with waste woods.
Since the sampling of plywoods and pentachlorophenol-treated woods did not
7-51
-------
V«r I ab I • MOISTURE) dI•trI but Iont NotmI
Kolmoeorov-Smirnov d • .154419B, p ¦ n.«.
Chi-Square: 4.95B679, df = p • .0036985
weight percent
Figure 7-5, Histogram of moisture content for € processors.
-------
Variabt• ftStt j distribution: Lognorma!
KoIMosorov-S»Imov d ¦ .0782272, p » n.s.
Chl-Squ*r«: 1.283269, df « 2. p - .5264380
dry weight percent
Figure 7-6. Histogram of ash content for G processors
-------
Variable CHLORINE) distribution: Leonora*t
Ko1mosorov-S*Irnov d " .1388418, p « n.«.
Chi-Square: 3.142382, df « 2, p - .2070135
i ¦ r —r —j ——i r ¦ r —r——i———i—¦—~j t——r —r
dry weight percent
Figure
7-7.
Histogram of chlorine content for 6 processors.
-------
V«rI*bia SULFER \ distribution: Nor«i«t
KoIwoaorov-S«lrnov d • .1038372, p - n. ».
Chi-Squarc: 2.681082, df « 2, p « .2368174
' - i ¦ ! f —j :" [ —f— r~ *i " r~ ' > 1 ~ r~ ~~t~ ~i ~ 1 i 1 1—r
'dry weight percent
Figure 7-8. Histogram of sulfur content for 6 processors.
-------
exhibit leachable phenol derivatives and phenols were detected only at very
low levels in the waste wood Stream, it can be concluded that waste wood in
general has very little if any leachable phenol-based organic chemical
contaminants. Therefore, as previously suspected, organic contamination
should net be a major concern.
7.5.2.7.3 Minerals Analysis
The principle components of waste wood ash are silicon dioxide and calcium
oxide. Relatively large amounts of calcium are normally found in wood ash as
seen in the homogeneous woods analyses and prior experience with "clean" wood.
In waste wood ash calcium levels are diluted significantly by the amount of
silicon dioxide present. Silicon dioxide ash concentrations from wood boilers
are not normally as high as those seen in the ash from waste wood processors.
This processing requires removing wood from a mixed waste stream, and the high
levels of silicon dioxide are the results of sand, dirt and rock mixed in with
the wood. Samples showing high concentrations of silicon dioxide in the ash
also tended to have high ash concentrations in the wood. Some of the highest
values for ash in wood and silicon dioxide in ash were found at site 4. site
4 is a facility mainly producing mulch for landscaping which purposely does
not try to remove dirt from its product. At sites 1, 3 and 7 both ash and
silicon levels are lower than the other sites. These facilities use screening
techniques to limit dirt in the fuel and it is apparent that they are quite
capable of reducing soil contamination. Any processor wishing to control the
ash content of its product can do so by the proper application of shaking and
screening techniques.
Front end removal of noncombustibles from the fuel would result in less boiler
ash; however, the removal of soil may affect the quality of the remaining ash.
Using silicon dioxide as an indicator of the presence of dirt, some strong
correlations were discovered. As silicon levels decreased so did aluminum
levels. Iron levels also dropped somewhat with silicon but not consistently.
Titanium levels increased somewhat with decreases in silicon but not in such a
way to provide a strong correlation. Decreases in silicon and aluminum in
wood ash strongly increase calcium and magnesium levels while marginally
increasing potassium, sodium, sulfur, zinc and phosphorus. These elements are
from wood not soil.
Generally, the minerals analyses at each site were nearly identical which
strongly suggests that bulk ash characteristics are a function of processing
techniques.
Prom a boiler fuel standpoint it is desirable to limit the quantity of dirt
within the fuel, and in turn limit the quantity of boiler ash that must be
disposed of. The data indicates that a number of facilities, through
appropriate fuel processing techniques, are able to accomplish lower fuel ash
levels. However, facilities with reduced fuel ash levels may have higher
concentration levels of toxic metals in the ash. If a facility is handling a
large amount of painted wood, or CCA-treated wood or other wood types with
metal contaminants, the concentration of the contaminant metal will be higher
at reduced ash levels.
7.5.2.7.4 Metals Analyale
The purpose of the metals analysis for this project was twofold:
• to show variation in the processed wood fro® site to site as
well as within the sites; and
7-56
-------
• to determine accurate estimates of levels of these metals found,
in waste wood as fuel for use in predicting the environmental
properties of this material.
All the available metals data from the six processors has undergone a series
of statistical manipulations. Table 7-33, previously discussed, presents a
summary of the most relevant points. Figures 7-9 through 7-18 present
histograms of the concentration distributions of each metal. Appendix G
contains all the output tables from Statsoft * s CSS/3 statistical program.
The histograms indicate that all the data conforms to lognormal distributions
with most of the analysis showing low levels of each element (as predicted).
Each case has a few outlying values that are much higher than the rest. These
values raise the arithmetic averages significantly above the median levels.
Thus the standard deviation of the data becomes very large and misleading.
These histograms also quite clearly demonstrate the effectiveness of
compositing the samples. Compare the histograms of composite samples vs.
incremental samples. The comparative number of outlying values and how far
afield these values are is definitely lessened in the composite samples.
While the composite distributions do not conform to normal distributions, they
do begin to approach them.
Comparing the summary data of the "total metals" data versus the "five metals"
data listed in fable 7-33 also demonstrates the value of composite sampling of
bulk fuels. The composite samples generally have lower average and 95th
percentile values than the incremental analyses. Conversely, median,
geometric mean, and upper confidence levels for the median are lower for the
incremental "five metals" analysis.
Despite compositing, the variations in the data are still quite large. Care
should be taken in how these numbers are used when characterizing possible
plant emissions. As demonstrated by the distributions of the incremental
analyses, most of the samples have much lower concentrations of metals than
the arithmetic average of all the data. Compositing of samples normalizes the
distribution of data, more closely representing a large population of wood
fuel. Theoretically, compositing of a greater number of samples for analysis
will generate a normal curve when median and mean values are equal.
For permitting and engineering analysis calculations, extremely conservative
metals emissions rates can be calculated using 95th percentile values with and
without additional safety factors. Considering the nature of the data
presented above this practice seems far too stringent. These analyses suggest
that the geometric means within a reasonable confidence interval may better
characterize large populations of waste wood fuel because each of these
samples represents a small glimpse of the wood fuels from a particular
facility. Even collecting a number of samples at a single site is an
indication of only several hours of full scale feed to a facility. Therefore,
the geometric mean probably is most representative of long terra operation
conditions and the geometric mean plus one or two standard deviations is
probably more representative of short- term variations.
7.5,2.7,5 TCLP
Of the twelve TCLP tests performed on laboratory ash for this project six
samples failed the TCLP test for chromium. One of those failed for lead. All
the other samples had some detectable .amount of chromium in the leachate, two
of which are more than SO percent of the regulatory limit. Arsenic was
detected once in the leachate at a level 75 percent of the regulatory limit.
7-57
-------
UviaftJa MSSNZC : dlitf-ibut loni Lognor-Ml
XglaowrarSaimM d • .S*Z7f73« p * ru«.
Oii-S«ur«i 1.4»4T77. if • i# d • .tUMSI
i i -ft
i i
« * « * I § I I I ! ! 1 1 1 1 I
ppm. in dry wood
Figure 7-9A. Composite samples frequency histogram.
Varl«ftl« MKXXC l distributions Lamarmi
kdinaparwteir-nav d ¦ .MCZTSS. m • ft.*.
0\i-%+ur*i T. 5*7*17. df • •» P • .mwff
m
.,...,i f * < 11< 11 jt »tf I im f rtf f m ij
ffitm
, t, gp ...I... fgt. i.... i„ m,
• 2 8 5 S f 8 S S 5 | * K 1 | 1 | g | | || | | | f
in dry wood
Figure 7-91. Incremental samples frequency histogram.
Exp«c*ad
Ew«f»d
7-58
-------
OAOKZUHj dl»»ributlo«: Low»orm»l
¦U*ao«or«vSairnav d * .:1M173> » « ».».
*.MS2U, a# « * ¦ .»«7W3
ExMetad
* 8 « S I ! 1 1 I I I I I
ppm.ii dry wood
Figure 7-10A. Chromium composite samples frequency histogram.
Varltfela CWJfiKIun; dl*tnbutiw
Itelaeaerw-Saimow d « .IZ71I33, p • n.«.
OU»Snu*r»t« 1.19137V, df ¦ t, p •
"J" "" I ' "T1
1 j—1~
&9«et«d
" « « « 5 ? « 5 ! S J S M 5 I I J ! : I 5
pptn, ill Ay wood
Figure 7-10B. Chromium incremental samples frequency histogram.
7-59
*
-------
Varlafcla LEAD I (Hstritvt l«ni Ueerwmel
Keleogorev-Seirrwr d • . P * ft'.*.
8«i-Mu«rvs Z.ZTZSg*. M * I. » • .£UtM3
22 1 1 i ' ^ i ¦ * r™^"" 1 * 4 '
Zt
ppm. in dry wood
Figure 7-11A. Lead composite samples frequency histogram.
V»ri«toi« LEflO i SI*tri6«tion» LmmtmI
Kolao«or«v-a»irn0w d • .2238514, » ¦ n.s.
Oii-S«Mr«t l.ima, d* • 3, l» ¦ .7417974
ppm, in dry wood
Figure 7-113. Lead incremental samples frequency histogram.
7-60
-------
Variafela TITJMUU JI»rrl»utloni UwnarMi
Kelaeeom^ieirnev 4 • .I379t#8. » • «.».
x«.*ti7x. .»U
I t l I I l
t i j—
" * s « S 3 ! S I £ I 8 I I I ! I 3 S S I I
ppm, in dry wu«i
Figure 7-123. Titanium incremental sauries frequency histogram.
7-61
-------
VariMla ZDC l di*tr>butiant Loaner**)
Keleoecrwleirnev d • .t?3M7t, p > n. i.
OU-6»ur«i 3.915517, tff « 4, » • .2K374S
! 5 5 ? 2 S * I 3 I 8 ! S I 2 ! I I I
ppm. in dry woa
-------
Variant* MtCUN I dl»»rlbu»loni LoflnorMl
Kclaotorov-Sairnov d • „Wt9m, p • tut.
Olhswtt I.HSU, df - 3, P « .isssm
ppm,in6y wood
Figure 7-14, Barium composite samples frequency histogram.
VirittH SHOKEJH l d)«trlbutlon Uaanor-Ml
Kolaowarov-Sairnov d ¦ .lSfT23S. p » n.«.
Chi-Scuwdt Z«.K3M. d« • «. p » ,0008838
|4 r 1 'I' i i j "1 ™"[ 111 f "" f 1 1 "i " 1 I1 t J -: "V -ul T
13 —
«•><••>»»<•••*«
ppin, iadry wood
Figure 7-15. Cadmium composite samples frequency histogram
7-63
-------
VariAtila COPPEJt i distrtbutioni LospotmI
Xoiao«arov-Salrnov 4 ¦ . 1994471, p « «,».
chi-si»u*r«i z.rmns, ' ! • ! ! I I I ! ! ! * !i I X X ! S
ppm, in dry wood
Figure 7-16. Copper composite samples frequency histogram,
Vforitbl* HO®, J dl»trlbuttow LoanorMt
ICtlioiorw-birM* 4 • ,1M7K, » < .«
e»i-s«i*p«i • u » » ,i
E*P*et»
-------
Variable SIU*X 1 dl»trlbutioni Loanorul
Xslaoflorov-Sairnov d ¦ .1499*47, p » n.».
Chl-S*i*r*i I.19tt77, d# » 2. p ¦ .9168972
Ejmmtmt
mmmmm-i-irn-immm
ppm, io dry wood
Figure 7-18. Silver composite samples frequency histogram.
Barium and silver leachate were both detected in small amounts in separate
samples.
If the results of the laboratory-generated-ash were representative of boiler
ash, it would have to be disposed of at a facility permitted to accept
hazardous waste or be treated in some way to make the ash non-hazardous.
Sites 4 and 6 were the only sites to pass the TCLP. Comparing the median
values for chromium for each site, sites 4 and 6 had the lowest chromium
levels in wood of 13 ppm and 10.8 ppm. The next lowest facilities however
were not very far off in chromium levels. Site 3 has a median chromium level
of 13 ppm and site 7 has a level of 14,? ppm.
No correlation of elemental metal concentration with TCLP test failure could
be ascertained from this data.
Unfortunately these numbers still do not indicate any concentration above
which the sample will fail the TCLP test. If such a concentration exists, it
will have to be the concentration of chromium in ash compared to wood since
ash contents vary so much. However, it is important to again note that these
ash samples are laboratory generated and probably don't have the same matrix
as real ash generated in a high temperature furnace. As discussed in Section
7.3, real combustor ash may reach a fusion temperature that binds the chromium
to the ash, preventing leaching.
7.6 Wood Fired Combustors
7-65
-------
Two separate facilities burning wood as fuel were visited as part of this
project. Site 5 is a combustor that is permitted to burn
construction/demolition waste wood but at the time of the visit was burning
only clean untreated wood chips. Site i is a corabustor burning all sorts of
waste wood including construction/demolition, landciearing, and manufacturing
waste. In the following tables "clean" refers to material from site 5 and
"waste" refers to material from site 8.
7.6.1 Minerals Analysis on Ash
Table 35 presents the results of the minerals analysis performed on samples
from site 5 and 8. It is interesting to note that the bulk of the "clean"
fuel bottom ash is silicon dioxide. A large portion of the soil contamination
included in this fuel stream is a result of outdoor processing and storage..
The "clean" fuel fly ash breaks down more evenly into principal components of
oxides of silicon, aluminum., and calcium. The fly ash appears to also
contain some of the entrained soil but seems mostly to be the bulk of the wood
combustion by-products. Both sulfur and potassium oxides have fairly high
concentrations compared to the products of "waste" wood combustion and the
suaanary of the processor data. Since fly ash could not be collected at site
8, we cannot confirm if sulfur generally becomes part of the fly ash stream
and not the bottom ash.
With the exception of some noncorabustibles, the two types of bottom ash from
site 8 seem to have little variation in the principal components. Physically,
the sittings ash is generally a dark grey powder with some pebbles while the
hopper ash contains rocks, nails, and a somewhat darker color ash. Bulk
materials such as nails and rocks could not be processed and were therefore
removed using a 4mm sieve.
Calcium oxide levels found in both types of "waste" bottom ash more closely
resemble the "clean" fuel fly ash. This is more than likely a function of the
combustor-burning technologies involved. Site 5 utilizes a large portion of
undergrate air and has a turbulent bed while site 8 has no forced undergrate
air and a feed ram operating at seven-minute intervals pushing burning fuel
down the combustion ramp.
7.6.2 TCLP
Table 36 presents the results of the metals portion of the TCLP tests
performed on ash from sites 5-and 8, Full TCLPs were run. on each of the
samples except for the "clean'1 fuel bottom ash which was mostly rock. Of the
components tested for in the full TCLP test no organic® were found in the
leachate. As described earlier in the chapter, two of the ash samples were
split then treated with distilled water to initiate a pozzolanic process. It
was hoped that this process would bind the material and prevent leaching.
Quite unexpectedly, the result of this ash preparation on the "clean" fuel fly
ash seems to liberate many of the metals. Arsenic, cadmium, lead, and silver,
all below detection limits in the untreated fly ash leachate, increased to
above detection levels in the treated ash with cadmium approaching the
regulatory limit. Leachate values for chromium and selenium also increased
with selenium reaching a level of 0.98 mg/L. The regulatory level is 1.0 mg/L
for selenium. The results of the treating of the "waste" fuel grate siftings
ash leachate were mixed. Chromium levels increased in the treated ash
leachate while barium and lead levels decreased,
7.6.3 Elemental Metals Analysis
7-66
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Table 7-35, Mineral analysis on ash from two wood fired combustors, percent by weight of oxide of element.
Sample type
Nuunbe r
of
samples
si
Ai
Ti
Pe
Ca
m
K
m
5
P
Mri
Pb
Zq
sr
Ba
Unde-
ter-
mined
•CUuifi* tuel fly aah
1
11.28
0.62
r».9J
21.43
4. S6
0
7 89
2.4
n.dl
_
-
0.14
0. IS
1,03
tuy". bctt-nfl v*3h
I
76.95
8.72
0.47
4.09
3.95
1.72
1. 14
l.b8
0 u3
0.39
0.1 rf
».
-
0.03
0
-
*w »5te" Cu-t sittings a«h
1
30.43
8*6 ?
2.66
a. ?i
29.16
S. 03
?,26
3.5s*
0. 54
0.07
0
0
0.12
0.47
0
"Wtisfu" hun—r a.i.'i
l
J9.2i
10.29
2.9S
10.76
2h.
4.33
1.9B
j . 4S
0 Id
0.5
0.2b
0
0
0.13
0.7ft
0
fable 7-36. Toxicity characteristic Leaching Procedure (TCL.P) on ash from two wood fired combustors, rng/1.
Negative values represent detection, limits.
-a
i
a. Sample was wetted with distilled water and allowed to harden before it was sent to the laboratory for
analysis.
Mumber
Arsenic
Barium
Cadmium
Chromium
Lead
Selenium
Silver
Mercury
of
As
Ba
Cd
Cr
Pb
Se
Ag
Hg
samples
"Clean" fuel fly ash
1
-0,005
1.75
-0.001
0 . 009
-0.005
0.015
-0.001
-0.0005
"Clean" fuel fly ash®
1
0.124
0.94
0.7
0 . 047
1.41
0.98
0.002
-0.0005
"Clean fuel bottom ash
1
-0.5
1.1
-0.2
-0.2
-2
-0.5
-0.1
-0.1
"Waste" fuel grate siftings
1
-0.005
2.4
-0.001
0.42
0.42
-0.005
-0.001
-0.0005
"Waste" fuel grate sittings"
1
-0.005
1.5
-0.001
0.006
0.006
-0.005
-0.001
-0.0005
"Waste" fuel hopper ash
1
-0.005
1.42
-0.001
0.017
0.017
-0,005
-0.001
-0.0005
US EPA Regulatory limits (as
5
100
1
5
5
1
5
0.2
of mid-1992)
-------
Table 7-37, Metals in wood combuator fuel or ash, ppm.
"Clean* wood combustor
wood fuel
Element
Number of
Average
Minimum
Maximum
Standard
samples
deviation
Arsenic
6
0.26
0.125
0.44
0.15
Chromium
6
2.50
2.5
2.5
0.00
Lead
6
4.33
2.5
9
2.91
Titanium*
6
45.47
27.4
58 .1
11.03
Zinc
6
13.50
11
14.5
1.45
Barium
2
72.75
67
78.5
8.13
Cadmium
2
0.05
0.05
0.05
0.00
Copper
2
4.75
4
5.5
1.06
Mercury
2
0.13
0.125
0.125
0.00
Nickel
2
4.25
2.5
6
2.47
Silver
2
0.03
0.025
0.025
0.00
"Clean' wood combustor fly ash
Element
Number of
Predicted6
Average
Minimum
Maximum
Standard
samples
deviation
Arsenic
6
8.82
27.67
16
38.2
9.42
Chromium
6
86.21
61.17 .
42
76
12.94
Lead
6
149.43
72.17
31
111
31.44
Titanium®
6
1567.82
164.17
133
209
28.18
Zinc
6
465.52
491.25
147.5
800
246.49
Barium
2
2508.62
1055
915
1195
197.99
Cadmium
2
1.72
4.065
0.63
7.5
4.66
Copper
2
163.79
107.75
61
154.5
66.11
Mercury
2
4.31
0.3875
0.125
0.65
0.37
Nickel
2
146.55
48.75
42
56.5
9.55
Silver
2
0.86
1.075
0.35
1.8
1.03
"Waste* wood combustor bottom ash
Element
Number of
Predicted0
Average
Minimum
Maximum
Standard
samples
deviation
Arsenic
12
74.22
48.3
28.5
78.8
14.34
Chromium
12
240.63
133.5
82
209
32.43
Lead
12
785.94
191.08
86
438
93.12
Titanium"
12
5350
1765.25
250
4790
1539.23
Zinc
12
934.36
469.17
280
850
190.57
Barium
4
785.94
1236.25
875
1465
278.22
Cadmium
4
14.06
0.07
0.21
0.025
0.09
Copper
4
351.56
614.5
258
1050
327.17
Mercury
4
1.14
0.125
0.125
0.125
0.00
Nickel
4
65. 63
54.125
45.5
61.5
6.57
Silver
4
1.77
0.875
0.31
2.35
0.99
a Titanium values are suspect. See text.
b. Calculated from "Clean* wood analysis using 2-9% ash in wood.
c. Predicted from Site 7 summary total metals analysis, titanium values from
site ? appear valid.
7-68
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Table 37 presents the results of the elemental metals analysis on wood and ash
samples from the clean wood combustor (site 5) and the waste wood combustor
{site 8}.
Metals concentrations in the "clean" wood fuel are, in most cases, much lower
than median concentrations from the construction/demolition wood processors.
Only barium, and nickel levels approach C/D levels, 84 percent and 85 percent
respectively of median C/D values. Mercury values were below detection and
nickel, values were at or about detection throughout the program. Barium is an
element found naturally in virgin wood.
From the ultimate/proximate analysis performed on the clean wood {see
appendices) the fuel is 2.9 percent ash. Assuming 1.00 percent of the metals
go to ash, predicted values of metals concentrations in the ash were
calculated. Comparing these values with the average of the actual fly ash
analysis shows higher concentrations of arsenic, cadmium, zinc and silver in
the actual fly ash which suggests that these metals became enriched in the fly
ash. The other metals which have actual fly ash metals concentrations lower
than predicted indicate that these metals either tended to enrich the bottom
ash or escape collection. Without bottom ash analyses which would allow mass
balance calculations, no definitive conclusion can be drawn.
7.7 Sample Accuracy and Reproducibility
7.7.1 Laboratory Variability
The results of any test plan can only be as accurate as the analysis reports
provided by the laboratories doing the analysis. Therefore, several split or
duplicate samples were sent to the laboratories to verify results. Split
samples were always taken after the material "had been size reduced. These
samples were also labeled so that the laboratories did not know these were
split samples. However, it is not always necessary to analyze split samples
to see variation in laboratory results. Minimum detection limits {MDLs)
varied significantly from sample to sample for the sarae analysis. Two
laboratories following the same protocol {EPA Method 1311, TCLP, November,
1990) showed drastically different detection limits. In an effort to explain
these variations, a review of available protocols and methods was made and
discussed at length with laboratory personnel. The following subsections
detail our findings.
7.7.2 Split or Duplicate Analysis
Of the tests performed on wood samples, the elemental metals, phenols and
minerals in ash analyses were verified using split samples. The TCLP test
required too much wood to generate ash and was too expensive to run
repeatedly. The ultimate/proximate test was not expected to vary
significantly. Four "five metals" analysis, four "total metals", one phenols,
and one minerals analysis were split.
The results of the duplicate metals analysis showed that the sampling
procedures provided reasonably representative results. Some interesting
trends were also noted. Analysis of split samples demonstrated relatively
good repeatability for the metals; arsenic, chromium, and copper. These
metals, as discussed throughout this report, are commonly found in CCA
pressure-treated lumber. The distribution of the metals in impregnated wood
should be fairly even. Since all the split samples were first ground and
mixed thoroughly before splitting, CCA treated wood particles in the samples
would be evenly distributed as well. Metals commonly found in surface
treatments of wood, such as lead, titanium, and zinc, fluctuated more widely,
but in most cases varied by a factor of three or less. Only a small fraction
7-69
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of the overall wood volume is ever touched by surface treatment. While sample
preparation methods attempted to create as homogenous a mixture as possible,
the analysis and averaging of multiple samples, as performed for this project,
seems necessary to characterize these metals in wood.
Many of the other metals sampled for were rarely above detection limits. In
the cases of cadmium and silver, when detected, the repeatability of the data
was very good {example: cadmium 1.00 ppm and 1,05 ppm). Mercury was never
det ected.
Only one duplicate phenol test sample was run. These analyses are expensive
and for the most part showed no detection. In this one case phenol was
detected in one analysis but not. in the split. All the other compounds
remained undetected but the minimum detection limits differed by a factor of
two. The concentration of phenol was measured at 1,10 ug/g while the
detection limit of the split was 0.66 ug/g. The phenols test requires a
relatively large sample {300 to 400 grams} which, coupled with the
heterogeneous nature of the wood and the proximity to the detection limits
should account for this discrepancy.
The minerals analysis of the first pressure-treated wood-sample was repeated
since it seemed highly unlikely that there would be 63.85 percent manganese in
the ash. The duplicate, however, showed a level of 62.83 percent manganese.
In fact the values of all twelve compounds sampled for were within ±2 percent
of each other. This demonstrates that the ash from wood combustion is by far
a much more homogeneous mixture than the wood fuel.
7.7.3 Minimum Detection Limits {MDL)
A minimum detection limit (MDL) is the value below which a laboratory cannot
accurately evaluate the concentration present in the sample. Thus a
laboratory may state something similar to no detection above MDL. This does
not mean that the compound tested for is not present but that the equipment
used cannot quantify how much, if any, is present. For.conservative purposes,
values equal to one half the detection limits were used for unbiased
statistical calculations [Gilbert, 1981).
Since detection limits were varying from test to test, it was of concern. The
testing laboratories were contacted to determine why this was occurring.
Each test is subject to influences of the matrix of the analyte, i.e., the
chemical and physical makeup of the analyte. In some cases, compounds found
in the matrix, other than those being tested for, will react with chemical
reagents or test equipment. The effects of these interferences vary. In the
case of metals analysis by acid digestion, the extraction fluid at times would
bubble out of the container when processed. In these cases samples would be
diluted with some non-reactive solution until they could be processed. The
greater the dilution, the higher the MDL rises. Another case of matrix
interference occurs when the matrix prevents further concentrating of
extraction solutions. As part of some analyses, a certain weight of analyte
is mixed with an extraction solution. The extraction solution is then
siphoned off and evaporated to concentrate the solution. While the extraction
solution is normally evaporated down to a standard volume, this is not always
possible. Compounds available in the matrix of the analyte {such as salt in
the water) may prevent or significantly slow evaporation.
7,8 Suggestions for Future Analysis
In reviewing the results of the laboratory testing for this project, certain
tests have proven to be adequate while others have been less than sufficient
7-70
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for characterizing wood and ash. The following methods for characterizing
wood and ash are suggested for future work:
• The us9 o£ ultimate/proximate analyses of wood fuel is a
consistent and reliable method for determining the basic fuel
properties. Since variations among samples analyzed are low, the
testing of composite samples is justified.
• Testing of phenol compounds yielded little in determining the
amount of phenol and phenol-formaldehyde compounds in the waste
wood stream. Future testing should evaluate the possibility of
testing for formaldehyde since this is a compound found in both
phenol-formaldehyde and urea-formaldehyde resins. Mao, the lack
of phenol compounds did indicate that certain types of organic
contamination were not occurring and should no longer concern
future investigations.
• The use of graphite furnace atomic adsorption appears to be a
reliable and repeatable method for determining arsenic, chromium,
and copper in waste wood. However, future testing for metals
contamination should be performed on ash samples when available.
The analysis of ash is an extension of the compositing performed
in this project. As suggested earlier in this report, composite
samples demonstrate a more uniform distribution of the data more
closely approximating a median value and representative of the
long-term combustion of wood fuel. By combusting wood into ash,
this not only composites a large quantity of wood but also
concentrates it so that metals such as cadmium, nickel and silver
might be more easily detected. The construction/demolition fuel
tested during this project had an average ash content of 7,8
percent dry weight. A sample of ash, therefore, should have
approximately 12 times higher concentrations of metals than the
wood it came from. Also the use of ash samples would alleviate
the size reduction and sample dissolving problems associated with
wood sample analysis.
• The use of the Toxic Characteristic Leachate Procedure (TCLP)
should be limited to actual facility ash instead of ash generated
in the laboratory. Under actual high temperature combustion
conditions, the ash reaches fusion temperature and potentially
laachable materials may become bonded within the ash.
Insufficient data is available at this time to prove or disprove
this theory. However, in other pilot and full scale studies,
similar types of waste wood fuels did not exhibit the same type of
metals leaching that occurred with the laboratory-generated ashes
in this project.
• For the next project phase it is recommended that testing of
various types of waste wood (both "treated" and "clean") be
conducted on fullecale boilers. This testing should take place on
boilers ranging in size from 50 to 300 million BTU/hr. The
combust ion systems should have appropriate particulate controls.
The testing should include a number of days of continuous
operation where numerous fuel, bottom ash, fly ash and
uncontrolled particulate emissions samples are collected at least
every hour. A material balance should be performed about the
system to determine how the metals are distributed in the various
ash fractions.
7.9 Bibliography - Chapter 7
7-71
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Bendel, Robert (UCONN) for ARS Group, July, 1990 Single ..Sample & Mean
Exceedance Probabilities.
Bicking, C.A. (1967), "The Sampling of Bulk Materials," Materials Research &
Standards. 7125:95-116,
Burr, Irving W., Statistical Quality Control Methods Marcel Dekker, Inc., New
York, NY, (1976).
CRC Handbook of Chemistry and Physics, 6_5fcfa Edition CRC Press, Boca Raton, FL
1985.
CSS: Statistica™ Manuals, Copyright Statsoft, Tulsa, OK, 1991.
Devone, Jay L., Probability & Statistics for Engineers. ft Scientist
Brooks/Cole, Monterey, CA, (1982).
Duncan, A.J., Bulk Sampling, Quality-Control Handbook < J.M. Juran, ed.), 3rd
«d., Sec. 2 5A, McGraw Hill, New York, p. 25A1-14.
Gilbert, Richard 0., Statistical Methods for Environmental Pollution
Monitoring, Van Nostrand Reinhold, New York, 1987.
Methods for Chemical Analysis of Water and Wastes. EPA-600/4-79-020, March
1979.
Proceedings From Eighty-Fourth Annual Meeting of. the American_Wood-Preservers'
Association. Vol. 84 American Wood-Preservers' Association, Stevensville, MD
May, 1988.
Shilling, G. Edward, AcceptanceSampling inQuality Control Marcel Dekker,
Inc., New York, NY, 1982. Chap. 9 : Bulk Sampling.
Test Methods for Evaluating Solid Waste Physical/Chemical Methods, SW846.
Third Edition, November, 1986.
7-72
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8.0 HIVIECWMlWai. IMPACTS OF WASH WOOD COMMJCTXCW - AIR
8.1 Introduction
Emissions of trace metals, sulfur and chloride from the combustion of waste
wood in boilers can be approximated using wood and ash concentration data such
as these presented in Chapter 7.0, These data, in conjunction with
conservative assumptions about the partitioning of these compounds between
bottom and fly ash or the reaction with components of the ash {in the case of
sulfur and chloride), can be used to estimate air emissions. Worst-case
assumptions about the partitioning (e.g. 100 percent of metals are contained
in the fly ash) can be used to obtain overestimates of emission rates;
however, emissions of organic compounds can not be estimated from wood and ash
composition data. Therefore, actual emissions data from the testing of
existing wood boilers have been compiled to supplement the wood and ash
concentration data obtained for this project. Although emissions data for
criteria pollutants (i.e. particulate matter, nitrogen oxides, carbon
monoxide, sulfur dioxide and total hydrocarbons! were obtained in the course
of compiling these data, the focus of this study was on non-criteria
pollutants such as metals and various organic compounds that are regulated as
hazardous air pollutants (K&Ps) by most state agencies.
In the absence of HAP emissions data for wood boilers, regulators have used
test data from residential wood combustion appliances to quantify emissions.
Although these data may be useful in identifying the types of pollutants that
may be formed from wood combustion, the emission rates from industrial wood-
fired boilers, as will be seen in this chapter, are significantly lower due to
the differences in combustcr design, combustion efficiencies and operating
conditions. The overall objective of compiling emissions data for this
project, therefore, was to summarize available HAP emissions data that are
more applicable to commercial or industrial wood boiler facilities. The
specific objectives of this task were;
• To identify pollutants that could be emitted from combustion of
various waste woods;
• To compile available test data on emissions from different wood
boiler designs firing different types of waste wood fuels;
• To summarize the test data in consistent units of measure and
reference;
• To identify and evaluate operating variables that affect the
levels of pollutants formed and emitted;
• To compare emission factors from commercial/industrial wood
boilers to those from residential wood combustion appliances; and
• To evaluate the capability of different boiler designs and waste
wood fuels to meet regulatory standards,
8,1.1 ley Findings
• Criteria and non-criteria pollutant emissions data from over 100
wood combustors have been located and summarized into consistent
units for convenient evaluation. Overall, the data should be
useful in characterizing emissions from wood combustors. However,
the statistical summaries should be used with caution due to the
8-1
-------
wide variation in boiler designs, sizes, fuel sources and
combustion controls represented by the many data sources,
• Relatively few sources of emissions data were found on combustion
of C/D, railroad ties, telephone poles or other "treated" wood.
Comparison of these data with those from "clean" wood combustion
at the same sources indicates that organic emissions are generally
not increased from combustion of "treated" wood. While metals
emission data from these sources were very limited, the data
indicate only slightly higher levels for "treated" wood
combustion,
• Organic compounds regulated as hazardous air pollutants that have
been measured in detectable amounts in wood combustor flue gas
include aldehydes, benzene, phenol, and polynuclear aromatic
hydrocarbons (PAH). These compounds are formed as products of
incomplete combustion and do not appear to be a function of wood
composition or source. Instead, they appear to be correlated to
emissions of carbon monoxide and total hydrocarbons, which are
also indicative of combustion inefficiency. "Good" combustion
conditions appear to minimize organic emissions.
• Metals usually found in wood combustor particulate include
arsenic, chromium, copper, lead, zinc, aluminum, titanium, iron,
and manganese. Emissions estimated from wood and ash composition
data summarized in Chapter 7 indicate that C/D wood samples
obtained for this research probably contained higher
concentrations of metals than wood fuel usually combusted at
existing facilities for which emissions data were found.
• Particulate emissions vary according to the type of particulate
control device (electrostatic precipitators and baghouses perform
the best, followed by wet scrubbers and mechanical cyclones).
• Metals control efficiency appears to be roughly equivalent to
total particulate control efficiency with the exception of
mercury.
• Chlorinated oi-ganic compounds, such as dioxins, furans,
pojychlorinated biphenyls, chlorinated phenols and chlor-benzenes
are usually measured at extremely low concentrations or were
reported to be less than minimum detection limits.
• Combustion of wood fuel with high levels of C/D or "treated" wood,
particularly CCA wood, may result in exceedance of state guideline
concentrations. Predicted exceedances of arsenic and chromium
guidelines imply that the amount of CCA-treated wood in a fuel
stream may need to be reduced by good processing practices to
insure compliance with state air toxics guidelines.
Section 3.2 provides an overview of the types of pollutants that may be
emitted from combustion of various waste wood fuels. Section 8.3 summarizes
the sources of test data used to compile the data. The major sources of test
data are described in some detail; all other sources are summarized in tabular
form indicating the types of boilers, fuels and pollutants tested. Section
8.4 describes the methods and assumptions used to compile the data. A summary
and evaluation of the test data are presented in Sections 8.5 and 8.6.
Finally, an evaluation of the compliance potential of various facility
configurations, controls, and fuel types to meet regulatory criteria is
discussed in Section 8.7.
8-2
-------
8.2
Identification of Pollutants from Waste Wood Combustion
As with any combustion process, all the criteria pollutants will be formed
from wood combust ion. Carbon monoxide (CO) and total gaseous nonmethar.e
hydrocarbons (TGNMHC) will be formed due to combustion inefficiencies. Even
the most efficient boilers could have up to several hundred parts per million
Cppm) of CO and a few ppm of TGNMHC. Nitrogen oxides {N0X) emissions are
inversely proportional to CO and TNMHC emissions; e.g., the higher combustion
temperatures needed to achieve low CO and TGNMHC emissions usually result in
higher levels of nitrogen in the combustion air being oxidized to N0X. In
addition, a component of total N0X emissions is directly proportional to the
nitrogen content of the fuel. Emissions of particulate matter (PM) are a
function of boiler design, fuel ash content, and effectiveness of particulate
control systems. Sulfur dioxide {SO,) is formed via oxidation of sulfur in
the fuel and appears to be also a function of the alkalinity of the fuel and
ash. More than 90 percent of the sulfur in the fuel reacts with alkalinity in
the wood and remains in the ash from the boiler {Oglesby and Blosser, 1980S.
Non-criteria air pollutants that may be emitted from wood-fired boilers and
are typically regulated as HAPs consist primarily of metals and various
organic compounds, Metals may be emitted as a result of their natural
presence in wood and from the non-wood portion of various waste wood fuels.
For example, as seen in Chapter 1, relatively small concentrations of arsenic,
barium, cadmium, chromium, copper, lead and zinc are found in clean wood fuel
obtained from silvicultural .activities. The source of metals may also be soil
that is brought into the boiler as a contaminant. Significantly higher levels
of arsenic, copper, chromium, lead and mercury are associated with waste wood
containing various treated or coated products. For example, combustion of
arsenic, copper and chromium contained in pressure-treated wood products would
result in emissions of these metals. Pigments in paint, which could also
result in emissions of metals when burning waste wood from building
demolition, include relatively high concentrations of lead, titanium, mercury
and aluminum.
Organics are usually emitted from any combustion process as products of
incomplete combustion (PICs). Organic HAPs of potential concern from wood
combustion include formaldehyde and other aldehydes, benzene, phenol, and
polynuclear aromatic hydrocarbons {PAH). Some of these compounds,
particularly formaldehyde and benzene, both carcinogens, have been measured at
relatively high levels from residential wood combustion appliances. As a
result, the general public and some regulators have assumed that these
compounds are also emitted from commercial and industrial wood boilers even
though the combustion design and efficiency of the latter would be expected to
result in significantly lower PIC emissions. Other PICs of regulatory and
health concern associated with combustion of solid wastes include halogenated
compounds such as dioxins and furans, chlorophenols and chlorobenzenes.
Presumably, these compounds could only be formed if there were sufficient
chlorine in the combustion air or chlorinated compounds in the fuel and
inefficient combustion conditions. As will be seen later in this chapter,
limited stack testing of wood boilers has indicated non-detectable or
insignificant levels of these compounds are emitted.
8.3 Sources of Emissions Data
Most of the emissions test data on HAPs located for this research were found
in reports and papers that have been written in the 1991-92 time period and
were available only in draft form. The bulk of the data were found in a
relatively small number of reports on rather comprehensive test programs. A
data base of wood-fired boiler emissions compiled in 1990 by Concord
8-3
-------
Scientific Corporation for Environment Canada included relatively few entries
on HAPs using the normal literature search procedures (CSC, 1990). Most of
the data collected in that effort were on criteria pollutant emissions. The
process used to obtain data for the current research primarily involved
contacting state and federal agencies and associations involved in regulating
or operating wood fired boilers. The majority of data were obtained from
states in which a large number of wood boilers are currently operating. The
sources which contained the most comprehensive and useful data on HAPs are
summarized in this section. Each summary contains a brief description of the
type of combustor(s) , fuel type(s), test program objectives and pollutants
tasted. Table 8-1 summarizes all emission sources used to compile data for
this study, including those from which only criteria pollutant data were
obtained. {Editors note: Since publication of the original report in 1992,
most of the draft references have been published. The following text and the
Bibliography have been updated to reflect these changes.)
• Sassenrath. 1991 - "Air Toxic Emissions From Wood Fired Boilers" -
for the Timber Association of California (21) - Under sponsorship
of the Timber Association of California, operators of wood boilers
formed a pooled test program to consolidate emissions testing
efforts required to comply with California's Air Toxic "Hot Spots"
law (AB 258 88) . The reference summarizes the results of the
program. In addition, data summaries from all test runs at all
eleven facilities were obtained directly from the Timber
Association of California. Eleven different source tests were
conducted representing approximately 85 wood-fired boilers
operating in northern California. The eleven boilers included two
fuel cells, two dutch ovens, five spreader stokers, one air
injection and one fluidized bed. Emission control systems
included mechanical cyclones, wet scrubbers and electrostatic
precipitators (ESPs). The HAPs evaluated in the testing program
included toxic metals, benzene, aldehydes, phenolics, PAHs,
dioxins and dibenzofurans. The primary conclusions from the test
program were as follows;
Toxic metals are significantly reduced by high- efficiency
particulate collection devices required on new facilities.
Aldehydes and benzene were measured as high as one part per
million. Concentrations vary widely depending on the type of
boiler. Emissions are slightly lower for fuel cells and
dutch ovens than for spreader stokers, probably due to the
large area of hot refractive surface relative to the furnace
combustion zone.
Volatile organic concentrations in the stack rise with an
increase in carbon monoxide concentrations in some boilers,
but no similar combustion efficiency relationship could be
established between boiler types.
PAH emissions from properly operated wood-fired boilers are
very low.
• California Air Resources Board (CARB). 1990 - "Evaluation Test on
a Wood Waste Fired Incinerator at Pacific Oroville Power Inc.*
{5} - CARB conducted an evaluation test of the Pacific Oroville
2 Refers to reference number in Table 8-1 and in Bibliography.
8-4
-------
Table 8-1. Plant information for emissions data sources.
ID
Plant name
State
Boiler
MKBtu/hr
Fuel
Partic-
ulate
controls
Other
•mission
controls
Re£.
No.
Pollutants tested for
001
Aft on Generating station
wy
MR
168
MC WS
cc
1
Permits, criteria
002
Collins Pine Co.
CA
NR
56
MC ESP
CC
1
Permits
003
Co-Gen, Inc.
ID
NR
63
ESP
CC
1
Perjni ts
004
Hay Fork Co-Gen
CA
NR
236
MC ESP
cc
1
Permits, criteria
005
McNeil Generating Station
vt
SS
666
SILV CLRE
MC ESP
1,32
Permits, criteria
006
Texas Electric Co-Op
TX
NR
35
HC
1
Permits
00"?
I
sierra Pacific Industries
CA
SS
245
MC ESP
CC
1,2
Permits, criteria, metals,
PAH, aromatico, halogenateel
HC, aldehydes, phenol.'.!
008
Redding Power Plants A fc B
CA
SS
229
cuts
MC ESP
CC
14
Permits, criteria
009
Hudson Lumber
CA
NR
70
MC WS
CC
1
Permits
§10
Sierra Forest FroductB
CA
NK
140
MC ESP
CC
1
Permits
Oil
Yankee Energy Company
CA
FB
1*je
MC ESP
SUCK CC
1,2
Permits, criteria, metals,
PAH, aromatic*, aldehydes
012
Cal Ag Power
CA
NR
92
WW
CC SI
1
Permits
013
Gabriel Power
CA
MR
147
1
Permits 1
014A
Pacific Oroville Power, Inc.
CA
SS
321
SILV
MC ESP
CC
1,5
Permits, criteria, metals,
aromatics, halogentaed HC,
dioxins, furans
014B
Pacific Oroville Power, Inc.
- Urban waste
CA
SS
3 SO
SILV CURB CD
MC ESP
CC
5
Criteria, metals, PAH,
aromatics, halogenated HC,
dioxins, furans, chloro-
benzenes. chlorophenols, PCB 1
ois
Washington Water t Power
WA
NNR
560
1
Permits |
016
Evergreen Forest Products
ID
MR
1
Permits 1
017
Gold Kist:. Inc.
CA
NR
1
Permits |
018
ABITIBI
NC
NR
1
Permits 1
019
Carolina Forest Products
sc
NR
1
Permits I
020
Viking En e r gy
PA
NR
1
Permits 1
021
West Vaco Corp.
PA
NR
Permits 1
022
Louisiana Pacific
HE
SS
1
Permits 1
023
Port St. Jo®
PL
NR
1
Permits 1
024
Panorama Energy Corp.
NNR
1
Permits !!
025
Alabama Kraft
AL
NR
1
Permits 8
026
Stratton Power
MB
SS
1,26
1
Permits, criteria I
02?
Willamette Industries
rr
NR
Permits
028
Mart-ell Power
CA
NR
1
Permits
029
Ultrapower XX
CA
BR
148
MC ESP
CC
1
Permits
030
Ultrapower I
CA
NR
148
MC ESP
CC
1
Permits
031
Auberry Forest. Products
CA
NR
165
MC ESP
SNCR CC SI
1
Permits
032
Energy Factors Feather River
CA
PB
247
MC ESP FF
CC
Permits, criteria
033
Burney Forest Products
CA
SS
167
MC WS
SNCR CC
1
Permits
034A
Pacific Ultrapower Chinese
Station
CA
PB
370
CURE
MC ESP
SNCR CC
Permits, criteria, netals,
PAH, halogentaed HC, dioxins,
furans, rhlcrobenzenes, 1
chlorophenols. PCB |
(Continued)
-------
Table 8-1. Plant Information for emissions data sources (continued),
ID
Plant nam.#
State
Boiler
KMBtu/hr
Fuel
Partic-
ulate
controls
Other
emission
controls
Ref.
No.
Pollutants tested for
034B
Pacific Ultrapower Chinese
CA
NR
CLRE
Criteria, metals
Station (unc)
035
Fairhaven Power I
CA
MR
309
MC ESP
CC
1
Permits
036
Monterey Bay - BSP
CA
Mfi
230
MC ESP
SNCR CC SI
1
Permits
037
Monterey Bay - FF
CA
HR
216
MC FF
SNCR CC SI
1
Permits
038
Erath Veneer
VA
MR
32
MC
CC
1
Permits
039
Burlington. Industries
6A
HR
290
MC WS
1
Permits
040
Butte
CA
HR
127
MC ESP
CC
1
Permits
041
North Coast
CA
HR
309
MC ESP
CC
1
Permits
042
Placer
CA
NR
357
ESP
££
1
Permits
043
Fairhven Power II
CA
NR
226
1
Perm!t s
044
Co-Generation, Inc.
MI
HR
293
MC FF
CC
1
Permi t s
045
Louisiana Pacific Hardboard
CC
1
Permi t s
Plant
CA.
CB
127
SILV CLRE
MC BSP
1,3
Permits, criteria, metals,
PAH, aromatics, halogenated
He, dioxins,furans, phenols,
chlorlbenzennes,
046
chlorophenols, PCB
Wood. Pre»erver«, inc.
CA
NR
48
BM
MC
CC
1
Permi t s
04?
chowchilla II
CA
FB
191
£STT IF Sill
ollfv all
MC PF
SNCR CC SI
1
Permits
048
El Nido
CA
FB
152
BM
MC FF
SNCR CC
I
Permits
1 049
Five Points
CA
NR
240
BM
CC
1
Permi t s
1 050
Madera Capco
CA.
FB
400
SILV BM
MC FF
SNCR CC SI
1
Permits
051
Delano Ennergy Company
CA
FB
SILV BM
MC FF
SNCR CC SI
1,31
Permits, criteria
052
Mendota Biomacs Power, Ltd.
CA
FB
418
SILV BM
HC FF
SNCR CC SI
1,31
Permits, criteria, other
053
inorganics
Sanger
CA
NR
175
BM
CC
1
Permits
054
Superior Fans
CA
NR
100
SILV BM
MC PF
CC SI
1
Permits
055
TEDCO
CA
NR
259
CLR8 BS CD
1C ESP
SNCR CC SI
1
Permits
056
Ultrapower Fresno
CA
FB
402
SNCR CC
31
Permits, criteria
057
Miller Redwood Company
CA
CB
13.9
MC
2
Criteria, metals, PAH,
058
Big Valley Lumber Company
aromatics, aidehydes
CA
CB
105
MC
2
Criteria, metals, PAH,
aromatics, halogentated HC,
Roseburg Forest Products Co.I
aldehydes, phenols
059
CA
DO
79
MC
2
Criteria, metals, PAH,
aromatics, aldehydes
060
Roseburg Forest Products
Co. 11
CA
DO
85
WS
2
Criteria, metals, PAH,
aromatics, halogentated HC,
1
Catalyst Hudson company
aldehydes, phenols
I 061
CA
SS
142
WS
2
Criteria, metals, PAH,
aromatics, halogentated HC,
Georgia Pacific Corp.. - ca
aldehydes, phenols
062
CA
ss
215
WS
2
Criteria, metals, PAH,
Pacific Lumber Company
aromatics, aldehydes
063
CA
SS
214
ESP
2
Criteria, metals, PAH,
aromat ics,aldehydes
(Continued)
-------
fable 8-1, Plant information for emissions data sources (continued).
¦ '"f.'g,", 1 ""I '111 -IIM jl -II I ¦ 1'lrt ¦ ¦ !" '!¦ .I.BHI1J. I I — irae!|ii.n, III- 1,11. I .iiMp— 1 mrmiMlllililliiiM1. .I»w Ii.yjnj'n IT .11.1 mmmmrn-mmm i
ID
Plant name
Stat#
Boiler
MKBtu/hr
Fuel
Partic-
ulate
controls
Other
•mission
controls
Re£.
Mo,
Pollutants tested for
064
Wheelabrator Shasta Energy
CA
SS
339
CliRE
MC ESP
SI
1,2
Permits, criteria, metals,
Company
PAH, aromat ics, halogenatad
Bohemia incorporated
HC, aldehydes, PCB
065
CA
AS
61
MC
2
Criteria, metals, PAH,
066
Site 5 IRR)
SS
aromat ics,aldehydes
CLRB RR
MC ESP
SHCR CC
28
Criteria, metals, PAH,
aromatics, halogenated HC,
Confidential
aldehydes, PCS
06SA
CA
FB
332
SILV BM
HC ESP
SNCR SI
4
Criteria, metals, PAH,
aromatics, halogenated HC,
dioxins, furans,
chlorobenzenes,
Confidential - unconrolled
chlorophennols, PCB
068B
CA
KB
324
SILV BH
4
Criteria, metals, PAH,
aromatics, haloganated HC,
dioxins, furans,
chlorobenzenes,
e h1orophenna1s, PCB
070
pride Manufactut ir.g
m
SS
6.3
«
criteria, metala, aldehyd«s
071
Webster Industries
WI
re
34
6
Criteria, aldehydes
072
Kretz Lumber Company
WI
NR
8.1
6
Criteria, aldehydes
073
U.S. Stick Corporation
WI
DO
12
6
Criteria, metals, aldehydes
074
SNE Industries
MI
MR
13
6
Criteria, aldehydes
075
Zurn - University of Idaho
ID
SS
60
MC
7
Criteria, aldehydes
076
Xupp»rs Company
CA
CB
100
MC
8
Criteria, metals, aromatics.
halogenated HC, dioxins,
furans
078
Unknown 1
SS
450
10
Ctiteria, aldehydes
079
Unknown 2
SS
1200
HC GBF
10
CritBtla, aldehydes
080
Unknown 3
SS
640
ESP
10
Criteria, aldehydes
081
Unknown 3 - uncontrolled
SS
840
10
Criteria, aldehydes
082
Unknown 4
CB
4.7
CC
10'
Criteria, aldehydes
083
Drexel Heritage Furnishings,
HC
SS
16.€
MC
11
Permits, criteria
084
Thomasville Furniture Ind.
HC
SS
IS. 9
MC
11
Permits, criteria
Plant C
085
Craven Counnty Wood Energy LP
NC
SS
674
li
Permits, criteria
086
Ethan Allen Company
NC
SS
§.3
BC
ii
Permits, criteria
087
Thomasville Furniture
NC
SS
18.3
MC
ii
Permits, criteria
Industry
088
Georgia Pacific Corp, - NC
HC
MR
40
MC
n
Permits, criteria
089
Bay Front Bonerat ing Station.
WI
SS
202
RF
BC
13
Permits, criteria, PAH,
boiler #.2*
29
aromat ics, aldehydes
090
Wood Tech, Inc.
VA
NR
CLRB
HC
12
Permits
091
Energy Systeals KHW - wood
CT
CB
12.1
SILV
MC
21
Criteria, PAH, aromatics.
092
chips'
CT
aldehydes, other organics
Energy Systems KMW " hog
CB
9.5
CLUB
MC
21
Criteria, PAH, aromatics.
1
f««l*
aldehydes, other organics
I 093
ORTBCH - tree chips*
CT
S3
0.8
SIIiV
21
Criteria, PAH, aromatics,
aldehydes, other orqanies
(Continued)
-------
fable 8-1. Plant information for emissions data sources (continued).
ID
Plant name
Stat#
Boiler
MHBtu/hr
Fuel
Partic-
ulate
controls
Other
emission.
controls
Ref.
Mo,
Pollutants tested for
694
ortech - hog fuel*
CN
SS
0,7
21
criteria, PAH, arcmatics.
095
Site 1
aldehydes, other organic®
CM
MR
417
MC BSP
2 2
Criteria, PAH
09?
NC Study site K
NC
SS
S.3
S1LV
20
Criteria, PAH
098
NC Study cite EA (dry)
NC
SS
16.6
CLRE
HC
20
Criteria, PAH
019
NC Study site EA (wet)
ue
SS
28
SILV
MC
20
Criteria, PAH
100
NC Study site BP
NC
SS
27
CLRE
m
20
Criteria, PAH
101
NC Study site HH
NC
SS
5.5
CLRE
MC
20'
Cliteria, PAH
102
NC Study sits SF
NC
SS
12.6
CLRE
20
Criteria, PAH
103
NC Study site EL
NC
SS
13.2
SILV
20
Criteria, PAH
104
NC Study site WW
NC
PB
17.8
SILV
HC
20
Criteria, PAH
105
B&G Port Ivory Coaplex
NY
SS
320
SILV CD LAM
MC WS
25
Permits, criteria
106
Long Beach
CA
SS
200
CD LAM
HC WS
SNCR
25
Permits, criteria
1107
Blandin Paper Co, #5 boiler
MN
SS
180
RR
15
Criteria, metals, other
inorganics, PAH, aromatics,
halogenated HC,aldehydes,
other organics
108
¥ICQ8 Recovery Associates
m
SS
84
CLRE
11
Criteria, other Inorganics,
PAH, halogenated HC,
dioxins, furans,
chlorobenzen.es.
Northuood Pulp Hill -
basel trie
chlorophenols, PCB
109
CR
SS
422
CLRE
MC
18
Criteria, other inorganics,
ha1ogenat ed HC
1 110
Northwood Pulp Bill - treated
CN
SS
435
CURE OT
MC
18
Criteria, other inorganics,
halogenated HC
I 111
Unknown site 6
SS
ESP
10
Criteria, aldehydes
112
Unknown Site 1
cc
as>
BSP
10
Criteria, aldehydes
113
Bio Energy corporation
NH
SS
290
SILV
GBP'
CC
29
Permits, criteria
114
Prennch island Unit 2*
FB
205
CLRB
MC GBP
23
Criteria, aromatics,
Bi rchwood Lunber $ Ven««r
aldehydes
115
WI
SS
5.6
24
Criteria, aldehydes
Plant, (old)
116
Birchwood Lumber & Veneer
Plant
WI
BO
13.1
CLUB
MC
19
Criteria, metals, PAH,
aromatics, halogenated HC,
aldehydes, chlorcbenzenes,
chlorophenols
117
Alexandria Power Associates
LP
NH
SS
SS
218
25
Permits, criteria
lis
Whltefield Power fc Light
NH
SS
212
MC MSP
29
Permits, criteria
119
Treebrook 1
NH
SS
250
MC GBP
cc
29
Permits, criteria
1.20
Timea, Inc.
NH
SS
S3
29
Permits, criteria
121
Pineti ee Power - Tamworth
SB
SS
409
MC ESP
29
Permits, criteria
122
Pinetree Power - Bethlehem
m
SS
289
ESP GBF
29
Permits, criteria
123
Hemphill Power & Light
tm
SS
230
MC ESP
29
Permits, criteria
124
Ryegate Wood Energy Co.
VT
SS
300
MC ESP
SNCR CC
p»mit
Permits
(Continued)
-------
fable 8-1. Plant information for emissions data sources {concluded}.
Notes;
* Data from these references not used in statistical evaluations for reasons
noted in text.
Permits; permit limits only
Boiler Types:
SS = Spreader Stocker
DO = Dutch Oven
FB = Pluidized Bed
CB = Cell Burner
AS = Air Suspension
NR = Not Reported
Fuel Types:
S1LV = Silviculture
CLRE = Clean Recycled
BM ¦> Biamass
CO = Construct io/D«nK>l it ion Waste
RR = Railroad Ties
LAM = Laminated
OT « Other Treated
Particulate Controls:
MC = Mechanical Collector
ESP = Electrostatic Precipitator
WESP - Wet Electrostatic Precipitator
WS = Wet Scrubber
FF = Fabric Filter
GBP = Gravel Bed Filter
Emission Controls:
SNCE = Selective Non-Catalytic Reduction
CC = Commbustion Controls
SC = Staged Combustion
SI » Sorb&nt/1imestove Injection
Power Inc. (POP!) facility in June of 1988. The test results were
obtained from CARB in preliminary draft form in 1989 and ia a
final report in May 1990. The POP1 facility operates two spreader
stoker boilers in parallel, each controlled by three-field ESPs.
Emissions were sampled in the common stack that exhausts both
boilers. The test program was conducted to evaluate HAPs under
two separate scenarios, one when the boilers were fired with
"permitted" fuel and the second when the boilers were fired with
"urban wood waste" in the ratio of 70% "permitted" fuel to 30%
"urban waste wood". The HAPs evaluated included dioxins and
furans, metals, halogenated and aromatic volatile organics,
chlorobenzenes, chlorophenols, and PCBs. The facility was also
tested for all criteria pollutants. This study also evaluated
dioxin and furan concentrations in the ESP ash.
• CARB, 1990 - "Evaluation Test on a Wood Waste Fired Incinerator at
Louisiana Pacific Hardboard Plant, Orovllle Power California" (3}
- A similar test program to that conducted at POPI was conducted
at the Louisiana Pacific Hardboard Plant in September of If88.
This facility consists of a WeiIons four-celled wood-fired steam
8-9
-------
generator firing nonindustrial wood chips and bark permitted by
the Butte County Air Pollution Control District, Mr pollution
controls consist of a raulticyclone and ESP, This facility was
also tested for dioxins, furana, halogenated and aromatic volatile
organics, PAHs, chlorobenzenes, chlorophenols and PCBs in addition
to criteria pollutants. This study also evaluated dioxin and
furan concentrations in the ESP ash.
• CARS. 1990 - "Evaluation Teat on a Wood Fired Incinerator at
Koppers Company. Oroville California" (8) - A similar test program
to those conducted at POP! and Louisiana Pacific Hardboard was
conducted at the Koppers Co. in September cf 1988. This facility
consists of a WeiIons four celled wood-fired steam generator
firing nonindustrial wood chips and bark permitted by the Butte
County Air Pollution Control District. A raulticyclone is the only
air pollution control device. This facility was also tested for
dioxins, furans, halogenated and aromatic volatile organics, PAHs,
chlorobenzenes, chlorophenols and PCBs in addition to criteria
poilutants. This study also evaluated dioxin and furan
concentrations in the multiclone ash,
• CARS, 1990 - "Evaluation Test on a Fluidlzed Bed Wood Waste Fueled
Combustor Located in Central California" [4) - CARB conducted a
similar program in China Station during May 1988 to the other
three test programs conducted in Oroville. The tested facility
consisted of a fluidized bed boiler operated for electricity
generation and equipped with a multiclone and ESP for particulate
control and a selective non-catalytic reduction (SNCR) system for
NO, control. The test program was more extensive than the other
three CARB programs, collecting samples before and after the ESP,
The ash analyses were also more extensive. Dioxins, furans, PAHs,
chlorobenzenes, chlorophenols and PCBs were evaluated in the
composite of the bottom, multiclone and SSP ash, Metals were
¦ also analyzed in the fuel and in the composite ash.
• National Council.of the Paper Industry for Air and Stream
Improvement (NCASI). 1992 {10) - This report is NCASI's summary of
its effort to develop emission factors for formaldehyde from
wood-residue fired boilers representative of current design and
operating practices. NCASI tested formaldehyde emissions at seven
different sites, five of which were spreader stoker boilers with
ESPs or wet scrubbers. One site was a suspension-fired fuel cell
fired with a wood dust known to contain formaldehyde-based resin.
Data from a seventh site did not pass the program's quality
assurance criteria. Although the actual locations of the test
sit es were not disclosed in the report, the effort was conducted
out of NCASI's West Coast Regional Center.
Because there was no recognized standard or reference method for
formaldehyde sampling and analysis at the time of the test
program, NCASI collected three concurrent samples for three
different analytical procedures for each test run to compare the
resuit.s. The three test methods evaluated were (1) the
chronotropic acid procedure, (2) the acetylacetone procedure, and
(3) the pararosaniline procedure, each using colorimetric
analysis. In addition, the CARB's method 43 0, using the 2,4
din11rophenylhydrazine (DNPH) procedure with chromatographic
analysis was conducted at two test sites for comparison with the
8-10
-------
other NCASl sampling and analytical procedures3, A total of 37
data points were obtained from this program, the main conclusions
of the study were:
The emission potential for formaldehyde from wood-residue
fired boilers was considerably {more than one to two orders
of magnitude) less than from residential wood stoves. When
operated at CO concentrations of 500 ppir. or less, wood
boilers would be expected to erait formaldehyde on the order
of 0.001 Ib/MMBTU heat input; and
The information developed in the course of the test program
indicated that collection of samples from a filtered gas
stream in two midget impinges placed in series in an ice
bath, storage of the samples under refrigeration, and
analysis with the chronotropic acid and/or acetylacetcne
procedures was appropriate. Use of the pararosaniline
measurement procedure for this application satisfied quality
assurance criteria for only a small percentage of the time.
Comparison of the DNPH method with the colorimetric methods
at two of the sites indicated comparable values when low
concentrations were measured ( < lppm!.
• Wisconsin Department of Natural Resources. letter to CTD re:
Request for Stack. Test Data on Waste-wood Combustion (£). This
letter is a source of formaldehyde and manganese emission data
from six different wood-fired boilers in Wisconsin. Each of the
sources is a relatively small boiler ranging in size from 6 to 34
MMBTU/hr. Average formaldehyde emissions ranged from 0.00008 to
0.0062 lb/MMBTU.
• Interpol 1 Laboratories, Inc., "Results of the April 2.-4. 1991
Wood ..Combustion Emission Study At the Birchwood Lumber and Veneer
Plant In Birchwood,.... WI*. (new boiler) and "Results of the April 3 -
B-. 1991 .Wood Combustion Emission Study At the Birchwood Lumber and
Veneer Plant In Birchwood. WI" (19) and (24)• These two reports
are a summary of emission tests conducted at two of Birchwood
Lumber and Veneer Plant's wood fired boilers, an old six MMBTU/hr
spreader stoker boiler manufactured in 1918 and a recently
installed 20 MKBTU/hr dutch oven type boiler. The tests were
conducted in support of a wood combustion study of small
industrial wood fired boilers in Wisconsin. The tests included
determinations of particulate, trace metals, aldehydes, PAH,
benzene, and criteria pollutants. During the course of the
testing, boiler operating parameters in the new boiler were
intentionally varied to simulate "poor combustion" conditions.
The boiler was operated under normal conditions for the remainder
of the test runs in order to compare emission factors
representative of "good combustion" with "poor combustion".
Benzene emissions from the "poor combustion" runs were increased
by as much as eight times over the average of test runs
representing "'good combustion". Formaldehyde increased by as much
as five tines over the average of the "good combustion1' runs. PAH
emissions from the worst "poor combustion" run were approximately
four times higher than the average of the "good combustion" runs.
(Editor's note: This method has since been certified be EPA as
Method 0011)
8-11
-------
• Interpol1. Inc. - Results of the August 12 and 13, 1986Air
Emission ComplianceTests Forthe Railroad Tie Teat Burn On The
No, 2 Boiler At The NSP Bay Front Plant In Ashland. WI" (1.3..) ,
This report summarizes compliance tests performed at Northern
States Power Company Bay Front Plant in Ashland, WI during a
railroad tie test burn. Three test runs each were run for 100%
railroad ties and a 50:50 mixture of railroad ties and wood chips.
The boiler, a 200 MMBTU/hr B & W spreader stoker boiler built in
1953, was tested for particulates, carbon monoxide, benzene,
aldehydes, phenol and PAH. In general, the results show lower
aldehyde, phenol and PAH emissions for the 50% railroad tie runs.
• NYSERDA - "Results of the Combustion and ..Emissions Research
Project at the Mean Incineration Facility in Pittsfield.
Massachusetts" f171. Under contract to the Energy Authority, the
Midwest Research Institute conducted a series of tests at the
Vicon MSW incineration facility to investigate the relationships
between combustion and operating conditions and organic emissions.
The emissions tested for were polychlorinated dibenzo dioxins and
furans (PCDDs/PCDFs), polychlorinated biphenyls {PCBs},
chlorobenzenes, chlorophenols and PAH. Although the test program
primarily involved combustion of MSW, a PVC-free fuel consisting
mainly of wood and cardboard was combusted in four of the nineteen
test runs. The waste was segregated from the normal MSW fuel and
was not totally free of plastic {chlorinated} material, although
the chlorine content was .much less than that found in normal MSW.
The data from the test program, including runs where MSW was
combusted, indicates relatively low levels of PCDDs/PCDFs, about
the same as the lowest levels measured at other incinerators.
There was no evidence from the testing that the level of PVC in
the waste affects the levels of PCDDs/PCDFs emissions.
Concentrations of PCBs and PAHs were not significantly above the
levels in field blanks. Concentrations of chlorobenzenes and
chlorophenols were about 10 times higher than PCDDs/PCDFs, but
were still quite low, on the order of 0.001 ppro.
• North Carolina. Department of.natural Resources¦ "A POM Emissions
Study For Industrial Wood-Fired Boilers" (20.) . This study was
undertaken to establish pciycyclic organic material, or PAH
emissions from industrial wood fired boilers in North Carolina.
The seven boilers tested in the study were chosen to be
representative of the majority of the 400 or mors industrial wood
boilers in North Carolina when operating with good operating
practices. Four horizontal return tube boilers, one water tube,
one fluidized bed and one underfed unit were selected for testing.
The boilers were relatively small units, rated capacities ranging
from 5 to 70 MMBTU/hr, The results of this study indicated that
properly fired wood boilers can achieve PAH emissions at least as
low, and possibly lower than commercial boilers fired with
bituminous coal.
• Energy,...Mines and Resources Canada, "Combustion and. Emission
Research On Wood-Refuse Boilers. Vol. III. Part 2. Tabulated
Results For Site 1" (22)- This report summarises PAH and criteria
pollutant emissions from an approximate 400 MMBTU/hr Combustion
Engineering boiler fired with wood refuse. The wood refuse
sources include dry bark and chip-screening fines from the paper
mill's wood room, pressed sludge from the mill's effluent
treatment system and purchased mixed wastes (sawdust, shavings and
bark) from local sawmills. Although measured CO and hydrocarbon
8-12
-------
emissions from the test runs did not indicate good operating and
combustion conditions, measured PAH emissions were very low,
roughly equivalent to background concentrations in the blanks.
• State of Minnesota Pollution Control Agency, Office Memorandum of
October 23, 1987 re: Test Report. Review - Blandin Railroad Tie
Test Burn (15). This memorandum summarizes the results of the
railroad tie test burn conducted by Interpoll, Inc. at the Blandin
Paper Co. in Grand Rapids. The boiler is a spreader-stoker design
with a capacity of approximately 200 MMBTU/hr. The fuel fired
during the test program consisted of a mixture of approximately
24% railroad ties, 65% untreated wood chips and 11% coal on a BTU
¦basis. Compounds tested for included criteria pollutants, metals
(Cd, Cr, As, Pb, Hg), PAHs, phenols, cresols, pentachlorophenol,
hexachlorobenzene, benzene, aldehydes, HC1 and IIP,
• Electric Power Research Institute."Alternative Fuel Firing in an
Atmospheric Fluidized Bed Combustion Boiler1' (23) . This report
details the results of test burns of alternative fuels, including
wood and railroad ties, in a shallow bed atmospheric fluidized bed
combust or (AFBC). The boiler tested in this study was a AFBC
retrofit of the Boiler No. 2 at the Northern State Power French
Island Plant in Minnesota. Test runs originally included in the
database ranged from 100% clean wood to a 45:55 mixture of
railroad ties and clean wood. Initial baseline tests with 100%
clean wood showed insufficient mixing of the overfire air, which
led to incomplete combustion. Extremely high levels of CO and
organics (PAH, aldehydes, phenols) were measured under this
condition. As a result, data from this report were not included
in overall statistical evaluation of the database since the boiler
was not operated under good combustion conditions.
• Energy. Mines and Resources Canada. "Emissions and Performance
Characterization of Industrial/Commercial Biomass ..Combustion
Systems - Draft Final. Report" (21) . This preliminary draft report
summarizes the testing of two small biomass boilers, one KMW 3750
XW and one Ortech 300 KW combustion cell. The primary fuels used
in the emissions tests were whole tree chips and residues from
mixed wood species. The boilers were tested for emissions of
criteria pollutants, PAH, aldehydes and aromatics, .including
benzene. Since the tests represented very small boilers and
extremely high measured CO levels were indicative of poor
combustion, the test data from this report were not included in
the overall statistical evaluation of the database.
• Environment Canada. "Summary Report for a Test Burn of
Chlorophenol Contaminated Wood Wastes at Northwood Pulp Mill,
Prince George. B.C." (18 i. Environment Canada and British
Columbia Ministry of Environment conducted a series of tests on an
industrial wood waste (hog) fuel fired boiler at Northwood Pulp
and Timber, Ltd. to determine the capability of this combustion
system to destroy low levels of chlorophenols, dioxins and furans
that sometimes contaminate hog fuel. The test burns involved hog
fuel with and without adding chlorophenol solution. Chlorophenol
solutions were added ir. concentrations ranging from 50 to 400
ug/g. The emissions testing indicated a minimum dioxin and furans
destruction efficiency of 99.9993% and a minimum chlorophenol
destruction efficiency of 99,9917.%.
8.4 Data Collection Methodology
8-13
-------
A thorough review of the test reports discussed in Section 8,3 was performed
to compile data on wood fired boiler emissions factors. This section briefly
summarizes the major assumptions and conventions that were used to present the
data in a form that could be most conveniently evaluated.
In order to maximize the number of data points for subsequent analyses, data
from each sampling run from a particular report, rather than the average of
multiple runs were studied. Due to the variety of formats used to report
units of measure in the different sources of data, the emission data required
seme preprocessing for standardization of units. With the exception of
criteria pollutants, all emissions were converted to units of either
micrograms or nanograms per dry standard cubic meter {ug/dscm or ng/dscm)
corrected to 12 percent carbon dioxide (12% CO,} . Standard conditions were
defined as 68°F (20°C) and 1 atm (760 mm Hg). The dry volumetric basis
standardizes the data so that pollutant concentrations are independent of the
varying moisture content of wood fuel and the 12% C0; correction serves as a
normalization for varying excess air requirements of different boiler designs.
Criteria pollutant emissions were converted to units of pounds per million BTU
(lb/MMBTU}, a common emission factor basis used by regulatory agencies.
In some cases, insufficient data on operating conditions at the time of the
test program were available to convert reported data to the desired units.
Reasonable assumptions were made in those cases in order to make the
conversions. For example, some reports did not include gas volume rates
and/or heat input rates in 'order to convert from mass rates to concentration
units. In these cases, the EPA F factor {from 40 CFR 60.45), based on the
approximate composition of wood fuel was used, which is in units of
dscf/million Btu. In other cases, concentration units in some reports were
given with no reference to dry conditions or percent C03. For purposes of
data evaluation, these concentrations were assumed to be on a dry basis and
corrected to 12% C02. A summary of conversions used to standardize the units
of measure is included in Appendix H.
In many cases, pollutants that are tested are not measured in the stack at
quantities above minimum detection levels. The convention used to handle
these data points was to indicate the detection limit with a negative sign.
In subsequent statistical or graphical evaluation of the data, half of the
absolute value was used.
Several computer software packages were used to facilitate collecting,
standardising and evaluation of the emissions data. The database manager
DBASE IV Version 1.1 was used on an IBM-compatible personal computer to
organize the collected data. A spreadsheet program, Lotus 1-2-3, Version 3.1
was used for further organization, graphing and presentation of the data.
Statsoft's CSS: Statistica™ was used for statistical evaluation that was
beyond the capabilities of Lotus 1-2-3.
8.5 Criteria Pollutant Permit Limits and Test Data
Although the focus of this part of the project was on hazardous air
pollutants, much data were collected on criteria pollutant emissions from the
various boiler types. Table 8-2 summarizes test data and permit limits for
more than a hundred different facilities. The values reported for test data
represent the averages of compliance test data. The data are also sorted by
boiler type,
8.6 Summary and Evaluation of Non-crit«ria Emissions Data
8-14
-------
Table 8-2. Criteria pollutant permit limits and test data.
(Ib/MMEtu)
Boiler:
Particulate Matter:
Nitrogen Oxides:
Cartoon Monoxldet
Sulfur Dioxide:
Hydrocarbons: (1)
Riant Name
Type MMBtu/hr
Permit
Tested
Permit
Tested
Permit
Tested
Permit
Tested
Permit
Tested
11?
Alexandria Power Associates LP
SS
218
0.100
0.004
0.270
0.200
0.270
0,396
0.270
113
Bio Energy Corporation
SS
230
0.100
0.074
0.119
0.165
0.790
0.165
0.210
0.002
115
Birchwood Lumber & Veneer Plant (old)
SS
5.6
0.426
107
Blandln Paper Co, #5 Boiler
SS
180
0.020
0.052
0.039
033
Burney Forest Products
SS
167
0,020'
0.120
0.400
0.046
0.100
061
Catalyst Hudson Company
SS
142
0.042
0.253
0.006
085
Craven County Wood Energy LP
SS
674
0.041
0.002
0.350
0.235
0.660
0.273
0.077
0.006
083
Drexel Heritage Furnishings. Inc.
SS
16.6
0.671
1.027
086
Ethan Allen Company
SS
9.3
0.534
0.384
062
Georgia Pacific Corp. - CA
SS
215
0.066
1.490
0.033
123
Hemphill Power & Light Co.
SS
230
0.100
§.oot
0.270
0.210
0.270
0.220
. 0.270
106
Long Beach
SS
200
0.050
0.064
0.290
0.270
0.120
0.082
0.008
0.002
0.030
0.011
022
Louisiana Pacific
SS
0.150
MS
McNeil Generating Station
SS
666
0.007
0.001
0.157
100
NC Study Site BP
SS
27
0.206
OSS
NC Study Site EA (dry)
SS
16.6
0.128
OSS
NC Study Site EA (wet)
SS
28
0317
103
NC Study Slie EL
SS
13.2
0-279
101
NC Siudy Site HH
SS
5.5
0.183
09?
NC Study Site K
SS
5.3
0.152
102
NC Study Site SF
SS'
12.6
0.127
103
Nonhwood Pulp Mill - Baseline
S3
422
0.235
0.161
0.692
. 0.003
110
Northwood Pulp Milt - Treated
SS
*35
0.215
0,13§
0.866
0.008
063
Pacific Lumber Company
SS
214
0.002
1.240
0.020
o
£
>
Pacific Orovllle Power inc.
SS
321
0.036
0.011
0.140
0.124
2.300
1.567
LD
0.150
0.026
014Q Pacific Orovllle Power Inc.
SS
360
0.005
0.127
1.635
LD
0.020
122
Pinetree Power - Bethlehem
SS
289
0.030
0.042
0.191
0.192
0.191
0,158
121
Pinetree Power - Tamworth
SS
409
0.025
0.009
0.265
0.205
0.500
¦- 0.230
0.0004
0.096
0.0004
105
P&Q Port Ivory Complex
SS
320
0.100
0.107
0.300
0.219
0.220
- 0.155
0.008
0,005
0-060
OOfl
Redding Power Plants A&B
SS
229
0.110
0.010
0.115
0.29Q
0.343
0.010
0.001
0.100
0.017
124
Ryegate Wood Energy Co.
SS
300
0.007
0.250
0.300
0.093
0.030
007
Sierra Pacific Industries
SS
245
0.048
0.005
0.280
0.380
0.700
0.010
0.120
0.028
(Continued)
-------
fable 8-2. Criteria pollutant permit limits and test data (continued)
(Ib/MMBtu)
Boiler;
Particulate Matter
Nitrogen Oxides:
Carbon Monoxide:
Sulfur Dioxide:
Hydrocarbons: (1)
Plan! Nam®
Type MMBtu/hr
Permit
Tested
Permit
Tested
Permit
Tested
Permit
Tested
Permit
Tested
026
Stratton Power
SS
620
0.013
0.350
0.202
0.235
0.003
087
Thorn asville Furniture Industry
SS
18.3
0.785
004
Thomasvllle Fum. Ind. Plant C
SS
15.9
0.410
1.695
120
Tlmco, Inc.
SS
53
0.340
0,51 S
0.467
0.168
0.467
DJ17
119
Treebrook 1
SS
250
0.100
0.051
0.230
0-375
0,230
0.26®
078
Unknown I
SS
450
0.188
079
Unknown 2
SS
1200
2.780
0B0
Unknown 3
SS
MO
0837
081
Unknown 3 uncontrolled
SS
840
0.451
111
Unknown SMs 6
SS
371
0.668
112
Unknown Site 7
m
353
0.000
108
VICON Recovery Associates
SS
14
0.201
0.008
0.377
064
Wheelabrator Shasta Energy Company
SS
339
0.030
0.002
0.150
0.144
0.740
0.265
0,022
LO
0.083
0.004
118
Whltelleld Power & Light
SS
212
0.100
0.006
0.270
0.239
0.270
0.259
0.270
075
Zurn - U. ol Idaho
SS
60
0.252
0.270
0.343
0.066
089
* Bay Front Generating Station Boiler #2
SS
202
0.407
0.368
0.122
093
* ORTECH
SS
0,8
0.061
, 0.186
4.161
0,029
094
* OHTtTCH
SS
0.7
0.177
0.101
4,248
0,053
047
Chowchllta II
FB
iii
0.037
0.250
0.200
0.014
0.060
0§8A
Confidential
FB
332
0.015
0.187
0.054
LD
LO
0688
Confidential - Uncontrolled
Fi
324
0.193
0.050
LD
LD
051
Delano
FB
0.014
0.060
0,140
,0.033
0.080
048
El Nldo
FB
152
0.037
0.285
0.140
0.049
0.061
050
Madera Capco
FB
400
0.025
0.150
0.150
0.073
0.060
052
Mendola Biomass Power Ltd,
FB
418
0.020
0.014
0.068
0.059
0,021
0.016
0.003
0.002
0.003
LD
104
NC Study Site WW
FB
17.8
0.156
034
Ultrapower Chinese Station
FB '
370
0.070
0.150
0.022
0.098
056
Ultrapower Fresno
FB
402
0.016
0,010
0.080
0.030
0.028
0.005
0.030
O.OQS
011
Yankee Energy Company
FB
178
0.030
0.009
0.240
0.470
0.298
0.046
0.090
114
* French Island Unit 2 ;;
FB
201
0.387
0.101
1,062
0.006
116
Bkchwood Lumber § Veneer Plan!
00
13.1
0.361
0.191
0.452
0.028
{Continued}
-------
Table 8-2, Criteria pollutant permit limits and test data Icontinued),
(Ib/MMBtu)
Plant Nama
Bolter:
Type MMBtu/hr
Paniculate Malar:
Permit Tested
Nitrogen Oxides:
Permit Tested
Cuban Monoxide:
Permit Tasted
Sulfur Dioxide:
Permit Tasted
Hydrocarbons: (1)
Permit Tested
059 Rosaburg forest Products Company 1
DO 79
0,776
0.250
0.008'
060 Roseburg Foresl Products Company II
DO 85
0.066
0.697
0.005
073 U.S. Stick Corp.
DO 11.8
0.567
058 Big Valley Lumber Company
CB 105
0,144
2.929
0.00?
076 Hoppers Company
CB 100
0.011
0.143
0.057
LD
LD
045 Louisiana PaeHic Hardboard Plant
CB 127
0.020 0.006
0,100 0.110
0,170 0 036
LD
0.130 LD
05? Millar Redwood Company
CB 13 J
2.414
0.036
0.047
0.013
082 Unknown 4
CB 4,?
0.943
0»2 * Energy Systems KMW - Hog fuel
CB 9,5
0.231
0.171
3.355
0.002
09i • Energy Systems KMW - Wood Chips
CB 12.1
0.194
0.182
4,11$
UD
0.004
065 Bohemia incorporated
AS 61
5,229'
2.078
0.023
018 ABITIBt
NR
0.100
001 Alton General In 0 Station
NR 165
0.100 0.085
0,240 0.202
0.440
0.005
0.090
025 Alabama Kraft
NR
0.100
0.300
031 Auberry Forest Products
NR 165
0.140
039 Burlington iods.
NR 290
0.100
040 iuttt :
NR 127
0,180
0.173
0.126
012 ¦ CaiAg Power • /
NR 92
0.056
0.500
0.170
0.240
0.078
019 CaroMna Forest Products
NR
0.250
1.190
002 Collins Pine Co.
NR 56
0.170
0.200
0.350
003 Co-Gan Inc.
NR 63
0.030
0.170
0.220
0.060
044 Co-Generation mc.
NR 293
0.030
0.300
0.300
038 Erath Veneer
NR * 32
0.270
0.890
0.017 ;v:/v
0.160
01 i Evergreen Forest Products
NR
0.240
0.200
035 Falrhaven Power t
NR 309
0.040
0.200
0.40Q
043 Falrhaven Power II
NR 226'
0.060
0,200
0.350
0.070
049 Five Points
NR 240
0.030
0.200
0.150
0.070
0.060
013' Q.aisf|s» Powar
NR 147
0.043
: 0.410
0.410
0.090
0.090
068 Georgia Paciiic Corp. - NC
NR 40
0.430 - 0.661
0t7 Gold Kist Inc.
NR •
0.100
0.700
004 Hay Fork Co-Gan
NR 236
0.040
0.150
0.350
0.070
009 Hudson Lumber
NR 70
0.G5?
0.130
0.780
0.010
0.060
072 Kretz Lumber Co.
NR 0.1
2.564
(Continued)
-------
Table 8-2. Criteria pollutant permit limits and test data (concluded).
(b/MMBtu)
Plant Nam#
loiter;
Type MMBtu/hf
Paniculate Matter:
Permit Tested
Nitrogen Oxides:
Permit Tested
Carbon Monoxide:
Permit Tested
Sulfur Dioxide:
Permit Tested
Hydrocarbons: (1)
Permit Tested
028 Mart ell Power
NR
0.024
0.170
0.580
0.067
03® Monterey Bay - ESP
NR 230
0.018
0.094
0.150
0.027
0.027
03? Monterey Bay - FF
NR 216
0.029
0.063
0.038
0.027
0.027
041 North Coast
NR 309
0.040
0.200
0.400
0f4 Panorama Energy Corp.
NR
0.170
042 Placer
NR 357
0.157
023 Port St. Joe
NR
0.100
0.300
053 Sanger
NR 175
0.022
0.073
0.091
0.052
0.042
010 Sierra Forest Products
NR 140
0.070
0.140
0.640
0.110
0.120
095 Slt«1
NR 417
0.023
1.132
0,007
0.013
054 Superior Farms
NR 100
0.022
0.165
0.229
0.062
0.066
055 TEDCO
NR 259
0.034
0.105
0.210
0,061
0.049
006 Texas Electric Co-Op
MR 35
0.300
0.080
1.100
0.200
0.200
030 Ultrapower 1
NR 145
029 Uttrapower i
NR 145
020 Viking Energy
NR
0.100
0.250
015 Washington Watar & Power
NR ' 560
0.044
0.180
021 West Vaco Corp.
NR '
0.100
0,700
027 Willamette Ms.
NR
0.700
046 Wood Preservers, Inc.
NR 48
0.200
0.080
0.450
0.160
090 Wood Tech, Inc.
NR 29
0.200
0.938
0.553
0.021
0.194
{1) Totat gasaous non-methane hydrocarbons
LD - toss than detection limit
-------
This section summarizes the non-criteria emissions data and evaluations
results. As there are a significant number of entries representing different
boiler types, operating conditions and emissions controls in the data summary,
one of the objectives of this study was to evaluate the effects of these
parameters on emissions. Therefore, statistical calculations were performed
on different subsets of the data., organized by boiler type, emission controls
and operating parameters representative of different combustion efficiencies,
primarily to develop emission factors that are representative of efficient
versus poorly operated and/or controlled boilers.
The descriptive statistical calculations that were performed on some subsets
of the data included means, medians and standard deviations as well as the
25:h and 75th percentiles from frequency distributions. For metals, emissions
were also sorted by particulate control device before additional statistical
calculations were performed. For organic emissions, the data were sorted by
boiler type and by different ranges of CO, corresponding to different levels
of combustion efficiency. Correlations between emissions and CO were also
evaluated graphically and histograms were plotted for some pollutants.
It became apparent early in the process of evaluating the data that the
emissions were not normally distributed, neither the data as a whole nor
within the sorted subgroups. As with many cases involving environmental or
pollution data sets, the data appeared to be skewed (asymmetrical) to the
right and more appropriately modeled as a lognormal rather than a standard
normal distribution. With "right-skewed data distributions, the existence of a
few data points at very high levels results in a positive bias to the mean or
arithmetic average. Large differences between the calculated medians and
means indicate skewed data distributions as do coefficients of skewness and
kurtosis that differ from zero. As a better summary of the data, the median
and geometric mean can be used instead of the arithmetic average.
Several cautions for use of the data summaries are appropriate. It is most
important to understand that the data do not represent a set of controlled
experiments performed on individual boilers to evaluate the effects of
operating variables on emissions. Instead, data from a large number of test
programs were compiled, representing many different boiler designs, sizes,
fuel sources, and combustion controls. The conditions achieved during some of
the test programs (in particular, compliance or performance tests) generally
are not representative of the range of "normal" conditions but of
"near-steady-state" conditions that are achieved by careful monitoring and
control of the facility. In addition, a large number of different testing
firms are represented, sometimes using different test methods and limits of
detection to measure the same types of emissions.
The minimum detection levels (MDLs} used in emissions tests can also
positively bias statistical summaries. For example, some compounds, like
dioxins or PCBs are tested for because of their potentially significant health
or environmental impacts, even though they may not be formed in quantifiable
amounts from wood combustion. To deal with values below MDLs, one-half of the
value was entered in the database for use in statistical calculations.
However, if MDLs are relatively high for a given test program, data treated
with this method could result in a significant Mas to the sustnary.
toother source of bias is the variation in the number of tests performed at
each plant. Since it was desired, to evaluate the largest number of individual
data points rather than the averages of a given test program, a relatively
high number of data points verifying a given operating condition at one site
may more than offset a small number of data points obtained from another test
report,
8-19
-------
Relatively few sources of emissions data were found on boilers combusting C/D,
railroad ties, telephone poles or other treated wood. These data were
summarized separately and compared with emissions from "clean" wood combustion
sources in order to evaluate the effects of contaminants on emissions. This
discussion is presented in Section 8.6.4.
Overall, the data summary should be very useful in characterizing emissions
from wood-fired boilers. The overall caution, however, is that the
statistical summaries should not be used exclusively without reviewing the raw
data used to calculate them,
8.6.1 Statistical Analysis of Different Boiler Designs
This section contains summaries of descriptive statistical analyses performed
on the emissions data from the different boiler designs burning clean or
recycled wood fuel. This summary does not include emissions from those
facilities burning "treated wood", such as railroad ties. A summary of those
data is presented in Section 3.6.4. It is important to emphasize that the
data summaries contained in this section are also not sorted by operating
parameters that have an effect on emissions, such as particulate controls and
combustion efficiency. These evaluations, which are presented in Sections
8.6.2 through 8.6,3, provide more useful information for predicting emissions
that are functions of these variables.
Table 8-3 contains a summary of descriptive statistics for spreader stoker
boilers, the boiler category for which the largest number of data points were
obtained. The compounds listed in Table 8-3 are grouped by emissions of
metals, organics and criteria pollutants. Based on the large differences seen
between the arithmetic means and the medians, as well as the relatively high
coefficients of skewness and kurtosis, it is'evident that the data are not
normally distributed. For these distributions, therefore, the median or
geometric mean are better indicators of the "average" of the data.
There are fewer data points representative of emissions from other boiler
types,- an abbreviated statistical analysis of these data has been summarized
in Tables 8-4 through 8-7 for dutch ovens, fluid beds, cell burner and air
suspension boilers, respectively. The minimum, maximum, average and standard
deviation of amissions data are presented in these tables.
8.6.2 Particulate and Metals Emissions
Total particulate and metals emissions data are discussed together in this
section because of the relationship between particulate and metals control
efficiency. Evaluation of the data clearly demonstrates the effectiveness of
high efficiency particulate controls on trace metals emissions.
Figure 8-1 is a histogram showing the distribution of total particulate
emissions according to type of control device. This figure shows that most of
the wood boilers equipped with ESPs achieved controlled particulate emissions
of less than 0.01 grains/dscf corrected to 12% CO, (all ESPs achieved less
than 0.05 gr/dscf), Boilers equipped with wet scrubbers achieved particulate
emissions in the range of 0.01 and 0.1 gr/dscf and most boilers equipped only
with mechanical cyclones had controlled particulate emissions of greater than
0,05 gr/dscf.
This information on total particulate emissions of the major particulate
control devices was used to structure the evaluations performed on the metals
emissions data. Metals emissions data were sorted into four ranges of total
particulate emissions that correspond to the different control devices. Two
sort ranges were created for ESPs; one representative of the best ESPs (<0.005
8-20
-------
Table 8-3, Summary statistics for spreader stokers Call values corrected to 12% C02) .
#of
25lh
geometric
75lh
standard
pollutant
units
points
minimum
percentile
mean
median
mean
pare wllle
maximum
deviation
Particulate Matter
gr/dsct
10®
0.0004
0.0030
0.0169
0.0181
0 0690
0.1196
0.6700
0.1064
Nitrogen Oxides
ppm
55
28
71
84
85
90
106
208
34
Carbon Monoxide
ppm
152
3
193
359
333
615
865
5000
671
Sullur Dioxide
ppm
26
NO
0.50
0.31
0.60
21.40
1.00
190.69
52.18
Hydrocarbons (1)
ppm
95
0,42
7.00
18.07
23.00
39.01
44.00
525.20
71.18
Arsenic
ug/dscm
te
0.100
0.163
0,750
0.204
5.428
6.630
36.200
10.576
Berllllum
ug/dscm
15
0.1500
0.1630
0.1817
0.1730
0.1840
0.2080
0.2485
0.0308
Cadmium
ug/dscm
17
0.1500
0.2000
0.3953
0.2SQ0
0.6283
0.7880
2.4200
0.6933
Chromium
ug/dscm
30
0.247
0.683
2.297
1 890
5 534
6 500
21.000
6.983
Hexavaient Chromium
ug/dscm
11
2.25
2.47
3.13
2.61
3.27
' 4.43
4.90
1.01
Copper
ug/dscm
14
1.00
2.66
5.88
383
10.78
16.90
31.30
10.70
Iron
ug/dscm
3
79
79
97
103
98
113
113
18
Lead
ug/dscm
18
1.00
1.66
5.20
4.13
11.43
11.40
51.00
14.88
Manganese
ug/dscm
16
i.o
3S.8
60.1
52.7
254,2
70.6
3136.0
769.9
Mercury
ug/dscm
15
0.18
0.25
0.40
0.33
0.48
0.95
1.01
0.32
Nickel
ug/dscm
18
1.50
1,66
2.55
2.36
2.82
4.16
4.86
1.28
Selenium
ug/dscm
15
1.500
1.630
1.999
1.905
2.076
2.485
3.490
0,633
Zinc
ug/dscm
15
2.0
20.3
68.9
106.8
161.1
277.0
471.8
158.2
Formaldehyde
ug/dscm
54
36
325
701
624
1660
1730
14615
2896
Acetaldehyde
ug/dscm
14
66
74
13®
115
173
224
414
125
Benzakfehyde
ug/dscm
0
Acrolein
ug/dscm
0
Benzene
ug/dscm
15
222
347
996
1120
." 1668
2403
6016
1788
Phenot
ng/dscm
. 6
16
32
867
7387
12120
21700
36200
14940
Chlorinated Phenols
ng/dscm
10
0.1
0.1
30.9
148.0
438.1
350.8
1807.8
649.2
N on-chlorinated Phenols
ng/dscm
6
16
33
887
7638
12429
22113
37138
15313
Total Phenols
ng/dscm
10
16
74
828
S09
7896
15337
37272
12922
Naphthalene
ng/dscm
33
6
19482
26447
108582
= 166198
303000
666000
188246
Carcinogenic PAH (2)
ng/dscm
¦ 36
5
21
269
484
v 2094
2020
17355
3650
Total PAH
ug/dscm
¦v 06
0,04
12.17
29.37
71.23
. 170.43
267.55
667.10
192.15
Dloxlns
ng/dscm
4
0.87
0.90
1.49
1.56
1.70
1.56
2.82
0.97
Furans
ng/dscm
4
2.668
3.352
5.540
4.613
7.189
4.613
16.860
6.530
PCBs
ng/dscm
0
Chlorobenzenes
ng/dscm
"if1™"
0
(1) Includes benzo|a|anthracene, benzo{a|pyrene, benzo|b|lluoranthene, benzo[kJtluoranlhene, chrysene.
dlbenzofa.h|anthracene. IndenoJl^.Slpyrene, and benzo{ghl|perylene.
(2) Total gaseous non-methane hydrocarbons as methane.
-------
Table 8-4- Summary statistics for dutch ovens Call values corrected to 12%
COj) .
Pollutant
Units
Count
Average
Maximum
Minimum
SUJ-Dw.
Arsenic
ug/dscm
14
6.646
36.10
NO
9.456
Beryllium
ug/dscm
6
0.3257
0.4920
0.2520
0.084618096
Cadmium
ug/dscm
6
3.665
6.890
1.140
2,139
Chromium
ug/dscm
11
16.05
51.20
0.5550
18.S7
Hexavaiant Chromium
ug/dscm
$
§.383
' 12.90
1.690
3.571
Copper
ug/dscm
14.
102.5967
164.3
30.60
42.26
Iron
ug/dscm
o
Lead
ug/dscm
13
5U1
91.50
4511
28.50
Manganese
ug/dscm
14
2572
CmI# r £•
9140
55.53
2712
Mercury
ug/dscm
7
¦ '54,41
372.2
0.4030
129.7
Nickal
ug/dscm
13
V 16.18
82,50
: 2.170
21.28
Selenium
ug/dscm
14
2.882
6.940
0.5760
1.586
Silica
ug/dscm
1
1,322
1.322
1.322
0
Zinc
ug/dscm
14
1670
2988
509.0
787.1
Formaldenyde(HCHO)
ug/dscm
16
394,8
1412
71.00
392.4
Acetaidenyde
ug/dscm
15
67.13
401.0
0.0600
109.8
ieraaWettyde
ug/dscm
9
0.8138
3.002
0.0980
0.8450
CrotonaJdehydi
ug/dscm
§
Hexanaldehyde
ug/dscm
6
¦Acrolein
ug/dscm
9
0,2439
0.9002
0.0306
0.2S32
i Benzene
ug/dscm
14
537.1
1118
16.00
584.4
Phenol
ng/dscm
12
2S15
11605
10.90
3045
Chlorinated Phenols
ng/dscm
12
7482
19929
0.4400
6106
Nor,-chlorinated Phenols
ng/dscm
12
5206
17854
13.41
4589
'Total Phenols
ng/dscm
12
12609
34005
13.85
10157
I Naphthalene
ng/dscm
15
86693
153000
17855
46606
!Carcinogenic PAHS (1)
ng/dscm
15
209B
5005
wV'UW
1757
[Total PAHs
ng/dscm
15
120.8
306.6
35.47
69.96
jOioxins
ng/dscm
0
jFurans
ng/dscm-
0
iPCBs
ng/dscm
0
jChloroCenzanas
ng/dscm
0
Particulate Matter
gr/dscf
20
0.1780
0.4300
0.0260
0.1276
'Nitrogen Oxtdas
ppm
§
100.9
130.6
70.30
17.57
j Carbon Monoxida
ppm
40
418.8
1100
§8.00
217.4
[Sulfur Dioxide
ppm
0
Hydrocarbons (2)
ppm
23
19.01
161.4
0,9600
33.3?
(1) includes benzofajanthracene, benzefafpymna. tNmzo[b]»luoranttiene,
benzo[kjf!uofanthene, crifystne, dib«nzo(a,hjanthracent, indenoji ,2,31pyr«ne,
ana benzo{gfii3peryiane.
(2) Total gaseous non-mathane hydrocarOons as methane.
8-22
-------
Table 8-5. Summary statistics for fiuidized beds (all values corrected to
12% C02> .
Pollutant
Units
Count
Average
Maximum
Minimum
Sid. Dev.
Arsenic
ug/dscm
15
11.35
' 32.60
0.1830
13.91
Beryllium
ug/decm
3
0.1945
0.2120
0.1830
0.0126
Cadmium.
ug/dscm
IS
1.591
5.000
0.1885
1.808
Oiremlum
ug/dscm
t7
19.31
70.40
a 2960
25.46
Haxavaient Chromium
ug/dscm
3
2,320
. 2,835
1.490
' " 0.532®
Copper
uQ/dsem
3
4.280
6,500
1.030
2.349
Iron
ug/dscm
12
5493
18793
47.10
7003
lead
ug/dscm
15
98.46
315.7
1.090
120.5
Manganese
ug/dscm
14
567.9
1799
atoo
688.8
Mercury
ug/dscm
3
0.2588
0.2730
0,2380
0.0150
Nick#
ug/dscm
IS
28.53
101.0
1.700
35.40
Selenium ,
ug/dscm
3
3.210
5.680
1.830
. 1.75V
Silica
ug/dscm
0
Zinc
ug/dscm
3
28.87
42,80
17.40
10.52
FormataehydeCHCHO)
ug/dscm
4
399.0
1517
12.00
645.7
AcetakJeftyde
ug/dscm
3
24.50
¦ 51.00
¦ 5.500
19.32
Benzaldehyde
ug/dscm
0
Crotonaidehyde
ug/dscm
0
Haxanaidehyde
ug/dscm
0
Acrolein
ug/dscm
0
Benzene
ug/dscm
12
13.60
64.00
3.000
15.34
Phenol
ng/dscm
0
Chlorinated Phenols.
ng/dscm
8'
1717
1989
1419
215.0
Non-chlorinated Phenols
ng/dscm
0
Total Phenols
ng/dscm
8
1717
1989
1419
215.0
Naphthalene
ng/dscm
14
79537
485000
3758
156868
Carcinogenic PAHs(1)
ng/dscm
14
1659
4619
26.50
1175
Total PAHa
ng/dscm
14
» 92.28
485.7
9.475
¦ 153.1
Olemins
ng/dscm
8
27.87
2Q2.S
0.*510
66.05
Furans
¦ ng/dscm
8
12.59
34.29
2.009
11.40
PCSs
ng/dscm
8
57.43
133.0
0.1190
48.97
Chlorobenzenes
ng/dscm
8
1518
3760
2.551
1367
Paniculate Matter
gr/dsc<
31
0.0762
0.8893
0.0011
0.1817
Nitrogen Oxidas
Ppm
44
92.59
134.0
29.37
. mm
Cartwn Monoxide
PPffl
58
116.1
380.0
1.270
109.0
Sulfur Dioxide
ppm
41
0.6364
4.840
NO
0.8076
Hydrocaroons (2)
ppm
36
0.9564
S.Q0G
NO
1.249
(1) includes benzofajartftraeen#, benzefajpyrant, benzofbffitjoranthene,
eer.2ofk]f!uoranthan«, chrysene,dibenzo{a,hlanthrac»ne, indsno{i,2(3Jpyreo«,
and b9nzo(gN)perylene.
(Z5 Total gaseous non-methana hydrocarbons as methane.
8-23
-------
Table 8-6, Summary statistics for cell burners(all values corrected to 12%
CO,) .
Pollutant
Units
Count
Average
Maximum
Minimum
Sd.Dev.
Arsenic
ug/dscm
12
3.859
18.10
NO
5.816
Beryllium
ug/dscm
S
1.779
4.150
0.1350
1.880
Cadmium
ug/dscm
12
2.070
9.200
0.4750
2.306
Chromium
ug/dscm
18
25.19
53.60
2.900
20.42
Hexavaient Chromium
ug/dscm
ft
98.05
'227,0
2.235
96.76
Copper • •
ug/dscm
§
83.57
185.0
' 35.10
54.17
Iron
ug/dscm
6
405.0
730.0
180.0
205.7
Lead
ug/dscm
12
108.2
444.0
1.780
133.3
Manganese
ug/dscm
12
1029
2060
1.450
869.7
Mercury
ug/dscm
6
0.8683
1.800
. . 0.2050
0.6837
Nickel
ug/dscm
It
9.026
23.10
1,415
€.892
Setenlum
ug/dscm
§
11.54
, 24.45
1.710
9.850
Silica
ug/dscm
§
Zinc
ug/dscm
6
305.3
410.6
162.0
92.67
Formaldehyde(HCHO)
ug/dscm
11
1020
1749
540.0
409-4
AcetakJeftyde
ug/dscm
§
478.2
964.0
180.0
275.6
BenzaUeftydt
! ug/dscm
0
CrotonakJehyde
ug/dscm
0
Haxamaldebyde
ug/dscm
0
Acrolein
ug/dscm
0
Benzene
ug/dscm
13
27.57
44.00
12.50
8.50S
Phenol
ng/dscm
3
323.3
670.0
10.00
. 270.5
Chlorinated Phenols
ng/dscm
7
122.5
240.3
3.480
75.68
Non-chJodnated Phenols
ng/dscm
3
656,7
1045
330.0
295.1
Total Phenols
ng/dscm
7
403.9
1135
3.480
358.7
Naphthalene
ng/dscm
t
208791
853000
750.0
307720
Carcinogenic PAHs (1)
ng/dscm
9
86.22
269.0
19.05
73.80
Total PAHs
ng/dscm
9
211.7
860.9
1.311
310. f
Dioxins
if if «lJti ilfll 1 M
ngjascm
8
2.902
8.486
0.1520
3.301
Furans
npQSCfp
8
5.017
14.15
0.4840
4.662
PCBs
ng/dscm
3
22781
64920
297.3
29819
Chtorobenxenes
ng/dscm
3
509.1
793.7
337.3
202.7
Paniculate Matter
gr/osci
11
0.4498
2.050
0.0040
0.6389
Nitrogen Oxides
ppm
17
94.88
mo
73.00
16.24
Carbon Monoxide.
ppm
56
931.5
3550
13.00
1201
Sulfur Dioxide
ppm
22
5.295
25.00
0.5000
8.963
Hydrocarbons (2)
pom
39
9.577
43.00
0.5000
10.901
Ct) includes b«nzo(a)anthracene. benzcKaJpyrene, 6tnzofbJflyortnth«nt,
twzofkjfluoranmene, chrysene. diberuo{a.h|anthracene> indeno{i,2.3lpyrene.
and b«nzo(ghi]peryiene.
(2) Total gastous non-methane hydrocarbons as m«thans.
8-24
-------
Table 8-7. Summary statistics for air suspension (all values corrected to
12% COj} .
Poduta-r
Units
Count
Average
Maximum
Minimum
SM.Oev.
Arsenic
ug/dscm
3
0,8620
0.9980
0.7550
0.1013
Beryllium
ug/dscm
3
0.4310
0.4990
0.3775
0.0507
Cadmium
ug/dscm
3
1.993
2.520
t.460
0.4328
Chromium
uoWscm
5
10.17
15.80
5.090
3.886
Hexavaient Chromium
ug/dscm
2
6.825
7,400
6.250
0L575O
Copper
ygWsero
3
31.33
32.40
29.60
1.236
Iron
ug/dscm
0
Lead
ug/dscm
3
15.10
18,60
11.50
2.899
Manganese
ug/dscm
3
1547
1674
1403
111.2
Mercury
ug/dscm
3
0.3545
0,3775
0.3120
0.0301
Nick#
ug/dscm
3
8.983
9.480
8.310
0.4937
S«fa«lum
ug/dscm
3
4,215
4.740
3.750
0.4064
Silica
ug/dscm
0
ZirtC
ug/dscm
3
281.3
266.3
269.3
8.250
Formaldehyde(HCHO)
ug/dscm
3
175.3
260.0
71. .00
78.40
Acetaldeftyde
ug/dscm
3
8-333
10.00
¦ 5.000
Z357
BenzakJehyde
ug/dscm
0
Crotonaldehydi
ug/dscm
0
Haxanaidehyde
ug/dscm
0
] Acrolein
ug/dscm
0
!Benzene
ug/dscm
3
3073
7000
474.0
2825
O
c
d?
£
' ng/dscm
0
Chlorinated Phenols
ng/dscm
§
Non-chlorinated Phenols
ft 9nzo[a]antfirac8tt#» benzofalpyana, berzo[b|flu0ranthif»e,
benzojxjfluoranthane, cnryseoe, diben2o(a,h]anthrac8rte, indenofl ,2,3}pyrene.
and benzofgNlDeryiene.
(2) Total gaseous non-methane hydrocart>ons as methane.
8-25
-------
Table 8-8. Trace metals emission rates versus total particulate control level8 (yg/dscm, corrected to
12% CO,) .
Particular Mailer 0-0 005 gr/dscl (0-11 ,*40 ugttscmj 1
Particulate Matter 0.005-0.01 gr/dscl {11.400-22.880 ug/dscm)
Pollutant
Coiinl
Avoraga
Maximum
Minimum
Sid. Dev.
Count
Average
Maximum
Minimum
Std.Dev.
Arsonic
vf
_ _ _ _
0 64
LD
0.14
13
0.75
2.80
LD
0.74
Beryllium
11
0 IB
0.22
0.15
0.02
1
0.21
0.21
0.21
—
Cadmium
12
046
1.80
0.15
0.47
13
0.37
0.61
0.20
0.13
Chromium
21
1.40
5.50
0.25
1.34
13
9.92
49.00
0.84'
15.43
Hexavalent Chromium
i
2.73
4.03
1.49
0.67
0
Copper
10
3.19
6.50
1.00
1.66
1
1.03
1.03
1.03
—
Iron
2
161.50
220.00
103.00
58.50
12
213.30
730.00
47.10
Lead
13
3.38
18.00
1.00
439
13
23.24
110.00
1.26
31.03
Manganese
10
43.79
107.80
1.80
51.10
13
104.98
400.00
1.45
140-56
Mercury
11
0.29
0.50
0.18
0.08
1
0.27
0.27
0.27
—
Nickel
13
3.13
5.50
1.50
1.46
13
4.02
9.10
1.65
2.59
Selenium
11
2,10
5.68
1.50
1.15
1
2.12
2.12
2.12
—
Silica
0
0
Zinc
11
63.57
369.00
2.00
100.83
1
26.40
26.40
26.40
—
Particulate Matter 0.01-0.05 gr/dscl (22.800-114,400 ug/dscm)
Particulate Matter 0.05» gr/dscl (114,400* ug/dscm)
Pollutant
Count
Average
Maximum
Minimum
Std.Dev.
Count
Average
Maximum
Minimum
Std.Dev.
Arsenic
10
11.33
36.20
LD
11.26
23
8.75
36.10
LD
11.39
Beryllium
9
0.22
0.27
0.17
0.04
12
1.10
4.15
0.14
1.37
Cadmium
10
1.32
2.42
0.23
0.71
15
3.55
9.20
1.34
2.24
Chromium
18
8.42
21.00
0.56
7.50
26
27.27
70.40
3.14
20.70
Hexavalent Chromium
8
4.25
6.10
2.25
1.26
11
56.24
227.00
1.69
84.93
Copper
9
25.01
32.70
, 15.60
6.62
20
96.87
185.00
29.60
47.00
Iron
1
240.00
240.00
240.00
--
3
10819.90
18792.50
3181.90
6377.39
Lead
10
39.85
88.80
11.40
22.33
22
102.00
444.00
1.78
123.92
Manganese
8
141.01
489.00
3.15
145.43
23
2133.17
9140.00
55.53
1961.75
Mercury
9
0.74
1.01
0.21
0.29
13
29.62
372.20
0.21
98.90
Nickel
10
11,76
a§ ca
OC.9V
1.99
23.68
22
18.91
101.00
• 1.42
22.85
Selenium
9
2.64
3.49
1.72
0.53
20
5.70
24.45
0.58
6.76
Silica
0
1
1.32
1.32
1.32
--
Zinc
9
399.50
665.00
188.50
171.63
20
1211.75
2988.12
162,00
950.76
Notsst
a Outliers removed from database for statistical analyses for reasons rioted in text.
-------
4#
1
I
I
&
I
O.OOQJ
®,0M
0.005 0 01 0.05 0.1 02 0.5
Total Particulate Matter, grains/dscf @ 12% C02
ESP Wet Scrubbed
Cyclone
Figure 8-1. Distribution of particulate emissions by control device.
-------
gr/dscf) and the other for those achieving between 0.005 and 0.01 gr/dscf.
The third sort range was structured to represent wet scrubbers (0.01 to 0.05
gr/dscf) and the fourth range represents mechanical cyclones {> 0.05 gr/dscf).
Table 8-8 presents the average, maximum, minimum and standard deviation for
each of the sort ranges. As expected from the plots of metals versus
particulate emissions, the average metal concentrations increase significantly
as the particulate emission range is increased.
Only one source of metals emissions was found in this study to contain actual
test data measured both at the inlet and the outlet of the particulate
control device tin this case, an ESP). These data, obtained from one of
CARB's test reports (4), was used to directly calculate metals control
efficiency across the ESP. The efficiencies for seven metals (As, Cr, Cd, Fe(
Pb, Mn and Ni) are summarized in Table 8-9. In general, all metals were
controlled by more than 97 percent, with the exception of Ni and Cd. However,
it is likely that actual control efficiencies for Ni, Cd, Cr and Pb were
higher, since most of the outlet concentrations for these metals were
determined to be below minimum detection levels. Control efficiencies in
these cases were calculated by using half of the detection level for the
outlet concentration. Unfortunately, the CARB test report for these data did
not contain uncontrolled total particulate emissions. Therefore, total
particulate control efficiency could not directly be compared to the metals
control efficiency.
However, controlled particulate emissions were less than 0.01 gr/dscf for each
of three tests, indicating very high overall particulate control. The data
summarized in Table 8-8 can also be used to provide another estimate of metals
control efficiency. These data infer that for most metals the control
efficiency is at least as good as total particulate control efficiency. This
judgment is made by comparing the averages of each metal concentration in the
fourth sort range (> 0.05 gr/dscf particulate) to those in the first sort
range !
-------
a
o
u
CM
THl
<§>
I?*
S
3
C ~ 4
a *~
5 , ~
~i. *&<*>
# 01 fotal" f>M ,°gi7d scf h%° toi
. ESP^ WS „ MC
Figure 8-2. Arsenic versus total PM.
ci
o
o
c>
rH
m
Bid.
O 10*
m
%
D
b »
a.
8.
*¦
»•
* »
~
* -
* »
*¦
~
#(L_j_—1_—_i——i . .¦. <¦—-j.
# #4
'tola I , *gr/d scf @*l2%*bol*
„ ESP # WS » MC
Figure 8-4. Copper versus total PM.
~
•>
« * * ,,,,¦. . : * „¦. , , .
^ 6 Total PM, gr/dscf @ 11% C02 1 "
. ESP# WS * MC
Figure 8-3, Total chromium versus total PM.
# " rfrota|0^M,'gr/ds°cf @°l2%#bo2' " '
. ESP# WS » MC
Figure 8-5, Lead versus total I'M {High Range).
-------
'total Pi, gr/dscf @ |2CC02
. \iSP. ws
Figure 8-6, Lead versus total PM (Low RangeJ,
"total P^gr/d^@12CCG2 **
„ ESP* WS
Figure 8-8. Zinc versus total PM (Low Range),
im
O
O
»~
0,me
-
-------
4
o
U 3
cs
s,
a2
•o
•5b
3
w%
s?
3
a i
97
(All 3 w/ ESP lass than MDL)(1)
ca
>91
(All 3 w/ ESP lass than MDL)
Fe
99
Pb
>97
(All 3 w/ ESP lass than MDL)
Mn
99
Hi
92
(2 of 3 w/ ESP lass than MDL5
(1) MDL = Minimum Detection Limit, taken as 0,5 of average MDL for w/ ESP
8-31
-------
Table 8-10, Metals control efficiency estimated from database.
Metal
% Control
Arsenic
97
Beryllium
84
Cadmium
87
Chromium
94
Hexavalent Chromium
95
Copper
97
Lead
96
Manganese
98
Mercury
99
Nickel
73
Selenium
63
I Zinc
95
8.6.2.1 Metals Emissions Estimated From Wood and Ash Composition
Although the metals emissions data collected for this study demonstrate the
relationship between particulate and metals control, the actual emission rates
as summarized in Table 8-8 may only be representative of "clean" wood. The
majority of facilities represented by the emissions data reportedly combust
"clean" or recycled wood. [However, based on site visits and wood analyses
data from this and prior projects, some of these facilities may also be
combusting some treated or C/D-derived wood), As discussed in Chapter 7,
although trace amounts of metals are present in "clean" wood, higher
concentrations are found in "treated* wood. Since "treated* or coated wood
can make up a portion of wood separated from construction/demolition debris,
metal concentrations in wood from such sources are also higher than from
"clean" wood sources.
In an attempt to estimate metals emissions that may be more representative of
C/D wood combustion, the wood composition data presented in Chapter 7 were
used with conservative assumptions about metals partitioning. First, the
metals were conservatively assumed to partition 100 percent to the fly ash
{i.e. no partitioning of metals to bottom ash) when the wood is combusted.
For example, the metals concentrations in the individual wood samples were
divided by the respective total ash content of the sample to calculate the
concentration of the metal in the ash. The distribution of metals in the ash
calculated by this method was then multiplied by the total PM emission rate
•representative of BACT {0.01 grains/dscf) in order to estimate metals ©mission
rates. The only exception to this method was Kg, for which emissions were
estimated by assuming that two-thirds of the Hg in the ash would be
volatilized and uncontrolled by the ESP or baghouse. Table 8-11 summarizes
the metals emissions developed with this methodology.
Comparison of metals emissions estimated from the C/D wood composition with
actual metals test data generally shows higher emissions estimated from the
8-32
-------
C/D wood analyses. For this comparison, metals emissions estimated from the
95th percentile of the wood composition data were compared with the maximum of
the stack test data for "good" ESPs (i.e. total particulate emissions less
than 0.01 gr/dscf). Arsenic, chromium, copper, lead, mercury and zinc
emissions from the wood analyses were approximately 3 to 2.2 times higher than
actual stack emissions. This comparison indicates that the C/D wood samples
obtained for this study probably contained higher concentrations of metals
than wood fuel typically combusted at existing facilities. Combustion of wood
fuel obtained from these sources, therefore, would be expected to result ill
higher emissions of some metals. It should be noted, however, that some of
the assumptions that were used in estimating emissions from the wood analyses
may be overly conservative. Nevertheless, these conservative assumptions
would probably not account for the order of magnitude discrepancy seen, for
copper and arsenic. Elevated levels of these metals in particular are
probably indicative of the presence of CCA-treated wood.
8.€.3 Organic Products ef Incoaplat* Combustion
In theory, emissions of organic compounds from combustion of any fuel are
produced only as a result of incomplete combustion. If all of the carbon and
hydrogen in a fuel are completely oxidized to carbon dioxide (CO,) and water
vapor there would be no carbon monoxide (CO) or unburned hydrocarbons (HC)
formed. Therefore, both unburned HC and CO are indicators of incomplete
Table 8-11. Estimated metals emission based on wood analysis data from six
processors.
Wood
Ash
Emissions
Median
95%tileb
Median
95%tile
Median
95ttiie
ppm*
yvy\»>v
ppsf
ppm
pg/dscm'1
ug/dscm
Arsenic
7,3
142.4
158.4
2933.0
3.31
61.36
Barium
87.0
550.0
1067.5
10658.9
22.33
222.99
Cadmium
0.7
1.6
9.7
43.9
0.20
0.92
Chromium
17.6
106.0
340.0
5760.9
7.11
120.52
Copper
22.0
84.67
329.8
2536.6
6.90
53.07
Lead
127.0
575.5
2281.6
21413.3
47.73
44.7.97
Mercury
0.13
0.13
1.2
e.i
G.08
0.38
Nickel
5,0
22.0
96.9
390.2
2.03
8.16
Silver
0.1
2.5
1.9
69.8
0.04
1.46 [
Titanium
391.5
1066.0
6413.6
11148.8
134.17
233.24 1
Zinc
134.0
340.0
1864.8
8843 .5
39.01
185.011
Notes:(a) Parts per million dry wood
(b) 95 percentile
(c) Parts per million in ash
(d) Micrograms per dry standard cubic meter, corrected to 12% C02
Example calculation; arsenic {median) in ash z emissions
158.4 * 10 < ppm * {0.02 lb aah/MMBtu) * (35.31 ft3/m3> * (453.6 * 10s pg/lb)
* {1/9280 * 1.65} {MMBtu/dscm « 12 % CO,} =3.31 pg/dscm
Calculation based on. assumed controlled PM rate of 0.01 gr/dscf {0.02
lb/MMBtu) except for mercury. Two-thirds of mercury in wood is assumed to
volatilize and be emitted from stack. Conversions from concentrations in
wood to concentrations in ash. based on ash contents of individual samples.
8-33
-------
combustion. The lower the emission rates of CO and HC measured in actual flue
gas from a particular boiler, the closer the combustion process approaches
perfect, complete combustion.
The organic emissions data collected for this project were evaluated using
these basic principles of combustion. Figure 8-11 is a graph of total HC
emissions versus CO for all boiler types. Figure 8-12 is the same graph, but
only including data for spreader stoker boilers. Both figures illustrate the
trend of increasing total HC emissions with increasing CO.
Table 8-12 is a summary of specific organic compounds for all boiler types
sorted according to different ranges of CO emissions that represent different
levels of combustion efficiency. The first two ranges, 0 to 200 ppmv and 200
to 500 ppmv CO are representative of "good combustion" conditions.
Most recently installed wood fired boilers with good combustion designs and/or
control systems achieve CO levels within these ranges. Well designed and
operated spreader stoker and fluid bed boilers usually operate within these
ranges. Older, less efficient or poorly designed wood boilers achieve CO
emissions in the third range, 500 to 1500 ppmv. Boilers operating under very
poor combustion conditions fall into the fourth range, greater than 1500 ppmv
CO. The data summarized in Table 8-12 demonstrate the trend of increasing
organic compounds with increasing CO emissions. For nearly all the compounds
listed, the averages of the compounds increase as the CO range is increased.
The same trends are alsodemonstrated in fables 8-13 and 8-14 for spreader
stoker and fluid bed boilers, respectively.
The specific compounds that are summarized in Tables 8-12 through 8-14 were
selected either because they have been identified as components of wood smoke
or because of their relative potential for adverse health impacts. Aldehydes,
such as formaldehyde, acetaldehyde and acrolein have been identified by health
professionals as pollutants of concern far persons suffering from asthma,
chronic bronchitis, and emphysema. Formaldehyde and acetaldehyde have also
been classified by EPA as probable human carcinogens. Benzene, polynuclear
aromatic hydrocarbons (PAH) arid phenol have also been identified as present in
wood smoke as well as most other combustion sources. Benzene and several of
the fifty or more compounds that make up the category of PAH are also
classified as potential carcinogens.
The other pollutants of interest that are listed in Tables 8-12 through 8-14
are chlorinated hydrocarbons, such as dioxins, furans, polychlorinated
biphenyls (PCB), chlorinated phenols and benzenes. All these compounds are
scrutinized by environmental regulatory agencies because of their suspected
carcinogenic potential. These compounds would theoretically only be formed if
chlorine was present in the fuel or combustion air. Although chlorine is
negligible in clean wood fuel, it has been measured in appreciable
concentrations in C/D wood fuel. Because the data summarized in these tables
represent the combustion of "clean" wood fuel, chlorinated organic compounds
were, in general, measured at extremely low concentrations. Furthermore, by
examination of the raw data, most of these compounds were reported at less
than minimum detection limits.
Limited data are available for comparison of emissions from C/D and other
"treated" wood fuel to "clean" wood combustion. The results from several test
programs {discussed in more detail in Section 8.6,4} generally demonstrate
that organic emissions are not increased due to burning of C/D and treated
wood. Metals emissions are also comparable to clean wood or marginally
higher.
In an attempt to further evaluate the relationship between combustion
efficiency and organic products of incomplete combustion, graphs of
8-34
-------
a Unknown
x Dutch Oven
2 Tbouwad* '
CO, ppmvd
# Air Suspension A Cell Burner
+ Fluid Bed A Spreader Stoker
Figure 8-11. Total hydrocarbons versus CO.
CO, ppmvd
ISM
2000
_ Best Fit Linear Regression +/— Std. Error of HC Estimate
Figure 8-12. Total hydrocarbons versus CO for spreader stokers.
8-35
-------
Table 8-12. Organic emission, rates versus CO stack concentration, all boilers.
fall values corrected to 12% CQ2)
Pollutant
Units
Carbon Monoxide 0-200 ppm
Carton Monoxide 200 500 ppm
Count
Avarage
Maximum
Minimum
Std.Dev.
Count
Average
Maximum
Minimum
Std.Dev-
FormaldehycJa
ug/dscm
46
660.8
5436.0
12.0
904.8
14
1081.4
10/3.0
71.0
9/4.7
Aceialdahyile
ug/dscm
20
212.80
954.00
3.87
245.46
7
89.64
340.00
10.00
104.59
BenzaldaMyde
ug/dscm
3
1.191
3.002
0.280
1.280
0
Croionaldahyde
ug/dscm
0
0
HuxanakJehyda
ug/dscm
0
0
Acrolein
ugftlscm
a
03579
0,9002
0.0851
0.3895
0
BWIZMft
ug/dscm
30
72.6
347 0
3.0
102.0
~
724.7
1343.0
133.0
448.1
Phenol
mj/tlscm
4
43
74
16
22
5
14528
36200
11
13727
Chlorinated Phenols
na/d&cm
17
770.8
1989 0
0.1
788.5
5
86.2
160.5
0.4
70.6
Non-chlorinated Phenols
«g/dscm
4
4*
74
1©
n
S
14900
37138
13
14066
Total Phenols
ng/dscm
17
781
1069
. 3
77®
5
14986
37272
14
14125
Naphthalene
ng/dscm
28
172860
at! 3000
6
226870
S
216389
666000
6500
213403
Carcinogenic PAHs (1)
ng/dscm
28
361.8
1989.0
5.2
642.3
ft
1640.8
11900.0
21.0
3666.6
Total PAHs
UflftlSCm
28
157.59
860.87
0.04
221.84
»
247.44
667.10
25.81
213.16
Oioxins
ng/dscm
13
11,405
202.480
0.152
53.225
0
Furaiw
ng/dscm
13
9316
34.292
0404
10.194
0
pea*
ng/dscm
1
8600
64920
60
21310
0
Chlorobenzenas
ng/dscm
0
1707.4
37600
' 397.3
1169,7
0
Pollutant
Units
Carbon Monoxlda 500-1500 ppm
Carbon Monoxlda 1500* ppm
Count
Average
Maximum
Minimum
Sid.Dev.
Count
Average
Maximum
Minimum
Sid. Daw.
Formaldehyde
ug/dscm
20
2125.1
12616.0
05.8
3211.6
1
14615.0
14615.0
14615.0
0.0
Acet aldehyde
ug/dscm
8
187.38
414.00
5.00
149.17
0
Benzaldehyde
ug/dscm
0
0
Crot on aldehyde
ug/deem
: 0
, ¦¦¦/".fa
H ex *n aldehyde
ug/d«cm
• Q
Q
Acrolein
ug/dscm
0
v-.>;0
Benzene
ug/dscm
14
21100
7000,0
12.5
2248 1
0
Phenol
ng/dscm
3
323.33
670.00
10 00
270.47
0
Chlorinated Phenols
ng/dscm
3
86,7
90.0
80.0
4 7
0
Non-chiorfnaied Phenols
ng/dscm
3
657
1045
330
295
0
Total Phenols
ng/dscm
3
743
¦ 1135
420
296
0
Naphthalene
ng/dscm
9
213367
530000
250
202030
0
Carcinogenic PAHs (1)
ng/dscm
9
11.5
269.0
0.7
92.1
0
Toial PAHS
u&fdscm
9
226 05
547.98
033
210.70
0
Oioxins
ng/dscrn
4
1.705
2.819
0.871
0.638
0
Furans
ng/dscm
4
7.189
16060
2-660
$.655
0
PCBs
ng/dscm
0
0
Chlorotoeruenes
nu/dscm
0
»
' 0
(1) Includes bwwolajanihracan®, benzo{a|pyrena. benzo{b|fluoranthen«, benzo{li|ttuoranlhene,
chrys«n0, dlbenzo|a,h|anihracena. Ind®no0.2.3)pyiena, and beniotgMlperylene,
-------
Table 8-13. Organic emission rates versus CQ stick concentrations, spreader stokers.
_____ (alt values corrected to 12% CQ2) ________
Pollutant
Un*s
Carbon Monoxide 0-200 ppm
Carbon MonoxfcJe 200-500 ppm
Counl
Avwayu
Maximum
Minimum
Std.Dov.
Count
Average
Maximum
Minimum
Sid Dev
r twnukJohytJa
ug/dscm
31
7?0.9
5496 0
36 2
1049.9
10
1426.1
2623 0
380.0
944.6
Aculaldehycio
ug/dscm
1
165 40
390.00
74 16
102.19
4
136.50
340.00
66.00
117.50
Bwualdohyda
ug/dscm
0
0
Crotonaldahyde
ug/dscm
0
0
HexanakJehyde
ug/dscm
0
0
Acrolein
ug/dscm
0
0
0.0
Benzana
ug/dscm
4
275.4
347.0
222.0
45.6
1
524.0
524.0
524.0
Phenol
ng/dscm
3
40
74
16
24
3
24200
36200
14700
8954
Chlorinated Phenols
ng/dscm
7
564,4
1807.8
0.1
699.0
3
143,3
160.5
134.0
12.2
Non-chlotlnaled Phenols
ng/dscm
3
41
74
16
24
3
24817
37138
15202
9157
Total Phenols
ng/dscm
?
582
1808
16
«8S
3
24961
37272
15337
9154
Naphthalene
ng/dscm
7
133790
321000
6
154554
7
245571
666000
®5G0
233697
Carcinogenic PAHs (t)
fig/dscm
10
32.7
132.0
5.2
36.7
7
2102.7
11900 0
21.0
4044.4
Total PAHs
ug/dscm
10
94.04
322.05
0.04
143.44
7
283.00
667.10
25.81
229.36
Dtoxms
ng/dscm
0
0
furaos
Ug/dscm
0'
0
PCOs
ng/dscm
0
0
Chlorobenzenes
ng/dscm
0
0
PoHutani
Units
Carbon Monoxide 500-1500 ppm
Cartoon Monoxide 1500» ppm
Count
Average
Maximum
Minimum
StdLDov.
Counl
Average
Maximum
Minimum
Sid.Dev.
Formaldehyde
ug/dscm
11
3157.0
12616.0
209,0
401O71
1
14615.0
14615.0
14615.0
0.0
Acetaldehyde
ug/dscm
3
241.33
414.00
86.00
134.47
0
Benzaldehyde
ug/dscm
0
0
CrotonaUlehydo
ug/dscm
0
0
Hexanaidehydo
ug/dscm
0
0
Acrolein
ug/dscm
0
0
Bon/one
ug/dscm
7
2664.4
601SJ
411.0
2022.2
0
Phenol
ng/dscm
0
0
Chlorinated Phenols
ng/dscm
0
0
Non-chlorinated Phenols
ng/dscm
0
0
Total Phenols
ng/dscm
0
0
Naphthalene
ng/dscm
2
501750
530000
473500
28250
§
Carcinogenic PAHs (t)
ng/dscm
2
19.5
21.0
18.0
1.5
0
Tout PAHS
ug/dscm
2
519.58
547.98
491.18
28 40
0
Dioxins
ng/dscm
4
1.705
2.819
0.871
0.838
0
Furans
ng/dscm
4
7.189
16.860
2.668
5.655
0
PCBs
ng/dscm
0
0
Chlorobenzenes
ng/dscm
0
0
(1) Inclutfos baruo(a)afi!hracen9, ben*o{a|pyrena, beruo{bltluoranthene. benioIM'luoranlhene,
chrysene, dibaruo|a,hlanihiacene. tndeno[1,2,3]py0H2Q(flhl|pafylene.
-------
Table 8-14. Organic emission rates versus CO stack concentration, fluidized beds.
tail values corrected to 12% CQ2)
PolManl
Unta
Cartxm Monoxide 0-200 ppm
Carbon Mwioxtde 200-500 ppm
Count
Average
Maximum
Minimum
Std.Dev.
Count
Averse®
Maximum
Minimum
Std.Dov.
FormaEdahyde
ug/dscm
3
26.3
540
12.0
19.6
0
Ac«taW@hyti«
u^dscm
3
24.50
51.00
5.50
19.32
0
Banzaldatiyda
Ǥttscm
0
0
CfotonakJaftyda
ugMacm
0
o
Hexanaidehyda
uOMocm
§
: 0
AcfoWn
ugMtcm
0
0
Benzene
wo/dscm
12
13.6
64.0
3.0
15.3
0
Phenol
noMsem
0
0
Chlorinated Phenols
ng/dscm
s
1711.2
1969.0
1419.0
227.0
o
Non-chMlna»ed Phenols
Hg/dscm
0
¦ ' 0
Total Phaooia
n^dscm
6
1711
: 1989
Kit
22?
0
Naphthalan®
n^Wtcm
8
129311
.: 486000
6320
192631
0
Carclnooenlc PAHs (1)
ftgUscfn
6
1080.9
1969.0
26.5
631.9
0
Total PAHs
ug/dscm
S
132.32
485.72
9.46
191.52
0
Dtoxlns
ng/sscnn
5
43.210
202.460
0.451
79.677
0
Fu«an«
noMacm
5
1*19$
. 34.292
f.fO»
,"12.591
' 0
PC8a
npMscm
S
92
133
60
m
0
Chlotobenzenea
«aM#cm
s
2426.3
3760.0
1276.5
mm
0
Pollutant
Units
CaitKm MontttUe S00-1500 Mm
Cartoon Monocle}* 1500* ppm
Count
Averaga
Maximum
Minimum
SMLDev.
Count
Average
Maximum
Minimum
Std.Dw,
Fotmaldahyde
ug/dscm
0
0
Acelaidehyde
«®Mscnt
0
0
Benzaldehyde
ug/dscm
0
0
Cfotonatdahyde
ug/dscm
0
0
Haxanaktohyda
waWacm
¦ 0
;j 9
Acrolein
MQftfecm
0
0
Benzene
ug/dscm
0
0
Phenol
n§Mscim
0
0
Chlorinated Phenola
ngMsmi
0
0
Non-chJortnataa Phtngte
ngMsem
0
¦;£=" o
Total Phanoia
ogfldaoai
0
0
Naphthalene
oQMscm
: 0
Q
Carcinogenic PAHa (t)
ng/dscm
0
0
Total PAHa
ua/dscm
0
0
Dtalns
ngfdscm
0
0
Furana
noWscm
0
:V0
,
PCB» .
fiflfdacffl
0
0
CWcwNfwanea
ngfttsem
0
¦ 0
(1) Iftcludas bamoiagpyfeM, bems|bjtiueraftihene, banzoik|fluor«Ritwi*,
chcyaana, dibanza{a,h|anUwacana. lndeno(1.2.3]pyrene, and t>a
-------
formaldehyde, benzene, phenol and PAH versus CO were constructed, A clear
relationship was not observed from all these plots due to considerable scatter
•of the data, in particular, for formaldehyde and phenol. Examples of these
plots are presented in Figures 8-13 and S-14 for formaldehyde and benzene.
Since the majority of PAH compounds are either particulates or adsorbed onto
particulates, the relationship between particulate and PAH concentrations was
also evaluated. A clear relationship was also not observed from these plots.
The scatter of the data or its inability to clearly fit expected relationships
is likely due to the nature of the database, i.e. the fact that there are so
many different sources of data rather than a few controlled experiments.
8.6.4 Emissions From C/D, Railroad Tiea and Other Treated Wood Fuel
There were relatively few plants that were found from the data search to be
combusting C/D, railroad ties or other treated wood as part of the fuel
supply. Emissions data were found from a total of three facilities that burn,
or have burned C/D wood waste, four facilities that burn or have performed
test burns with railroad ties and one plant that ran a test program with
chlorophenol-contaminated wood. These facilities are identified in Table 8-15.
Table 8-16 summarizes the average of the emissions data, from each of these
facilities. Where available, averages of test data from combustion of each
facility's normal or clean fuel are also presented for comparison.
The most meaningful use of these data is for comparison of the clean to the
C/D or treated wood test runs within the same boiler rather than comparison,
with different boilers burning clean wood fuel. The most extensive data for
this comparison are available from the CARB test program at the Pacific
Oroville Power plant which burns a mixture of 30% urban waste wood (C/D), from
the Site #5 facility, which conducted test burns of creosote-treated railroad
tie mixtures (50% of fuel makeup with chipped railroad ties by heat input),
and from the Northwood Pulp Mill in Canada which ran the test program with
chlorophenol-contaminated wood. Less extensive emissions data are available
from the Northern States Power facility (Bay Front Generating Station) for
comparison of two different mixtures of railroad ties (100% and 50% with clean
wood). Data only from the burning of railroad ties are available from the
Blandin Paper Co. facility,* therefore, no internal comparison was possible.
The data are summarized in Table 8-16. In general, comparison of data from
the different wood fuels within the same boiler demonstrate that emissions are
not significantly affected by burning C/D or treated wood. In fact, in both
data sets that allow a direct comparison of different wood fuels, emissions
are about the same for the C/D wood {Pacific Orcvilie) and railroad ties (Site
#5) test burns in comparison with the clean wood runs. In the CARS Pacific
Oroville test, arsenic was the only metal that was measured at a higher stack
concentration in the C/D nest burn. The other metals tested: chromium, lead,
iron and manganese were lower in the C/D test burn. All organics in the C/D
test burn, with the exception of benzene, were measured at lower
concentrations than in the permitted fuel test burn. It should be noted that
the Pacific Oroville facility tested by CARB represented very poor combustion
conditions during the test program. CO emissions averaged close to 1500 ppm
during the tests. Organic emissions during both series of test runs were
extremely high relative to other facilities operating under better combustion
conditions.
The data from Site #5 railroad tie test burn also generally indicated lower or
comparable emissions to the clean wood fuel tests. As expected, SO-, emissions
were higher than the normal wood fuel blend due to the higher sulfur content
of railroad ties. However, S02 emissions were still in compliance with the
AQMD permit limit when burning railroad ties. While some of the metals (As,
Cd, Cu and Kg) were marginally higher in the railroad tie tests, aldehydes and
8-39
-------
3000
2300
2000
1500
1000
soo
1000 1300
CO, ppmvd
~ Not Reported 0 Air Suspension
x Dutch Oven + Fluid Bed
Figure 8-13- -Formaldehyde versus CO, all data.
WM
2500
& Cell Burner
X Spreider Stoker
3000
Tkottaa^ *
CO, ppmvd
Best Fit Linear Regression Line +/- Std. Error (R squared = 032)
Figure 8-14. Benzene versus CO, all data.
8-40
-------
Table 8-15, Plants burning C/D, railroad ties, and other treated wood.
ID
Plant Name
Town
State
Boiler 1 Type of Wood
Type 1
Particulate
Controls
CO & NOx
Controls
Plants Burning Construction/Demolition Wood
106
014B
105
Long Beach
Pacific Oroville Power Inc.
P&G Port Ivory Complex
Long Beach
Staten Island
zoo
wtf *is» Tb*
SS
SS
SS
CD LAM
SILV CLRE CD
SILV CD LAM
MC WS
MC ESP
MC WS
SNCR
CC
Plants Burning Railroad Ties
089
107
056
066
Bay Front Generating Station Boiler #2
Blandin Paper Co. #5 Boiler
Uitrapower Fresno
Site 5 (RR)
Ashland
Grand Rapids
Malaga, Fresno
Wl
MN
CA
SS
ce
O w
w»***
FB
SS
DO
nn
RR
CLRE BM RR
SILV RR
IIO
Mv
MC ESP
SNCR CC
SNCR CC
Plants Burning Chlorophenol Contaminatec
Wood
110
Northwood Pulpmil!
Prince George
CN
SS
CLRE OT
MC
Boiler Types: SS « Spreader Stoker, FB - Fluidized Bed
Fuel Types; SILV ¦ Silvicultural, CLRE - Clean Recycled, BM ¦ Biomass, CD ¦ Construction/Demolition Waste,
RR - Railroad Ties, LAM « Laminated, OT « Other Treated
Particulate Controls: MC « Mechanical Collector, ESP » Electrostatic Precipitator, WS - Wet Scrubber
Emission Controls: SNCR - Selective Non-Catalytic Reduction, CC « Combustion Controls, SI - Sorbant/limestone Injection
-------
Table 8-16. Average of test data for C/D, RR tie, and other treated wood
combustors.
(all values corrected to 12%
Con«njcOorvD»mol)ttor> Wood
ftajfcoad T)m
PCP rraalad
PlMSlSfi
Long
Foit
Say
StaiMftl
Utatnwar
sn»s
ftactti
!WOOCj
Militant
Units
Orowila
Baach
Mny
RonJ
Fraano
Pulp Ml
(bMmA)
mm
(daan)
{RR}
{daan>
{PCP)
Paiticultt* M attar
gr/dtef
0.00600
0.00250
0.02840
0.04077
0.19079
0.00007
0.00495
0.00077
0.00090
0.10724
0.09901
Nitrogan 0»d««
PPm
00.57
09.28
149.14
119.02
209,09
79.00
07,00
•7.78
75.12
Carton Menaxid*
pp»
1427.1
1447.0
7X7
139.3
111.4
49.S
231,0
«sa.o
021.9
784.8
Suttur Otodd*
pprn
NO
NO
2.123
2:100
¦ NO
IS.000
Hydroca/t>ona(l)
ppnt
42.143
31.250
17.303
59.045
• 7.400
8.000
9.000
4-247
11.019
Araanie
ugMwfit
o.ias7
0.3600
: 0.1215
NO
0.0333
Sawil.. ,»*.
J tit
ugMacm
NO
NO
Cadmium
ug/daem
NO
NO
2.311
NO
0.000
Chromium
gg/dacm
5,100
4.100
93.102
NO
NO
Hwurariant ^rsnwini
ugMaent
Coeef
"Vf*1
uo/dKtn
1,897
¦ 3.097
iron
Laad
tig/dacut
ug/d«cm
mm
7.207
5««5
aw
2.111
1.087
1.197
Mmganaaa
ug/dacm
4a,w
18.300
31.500
1.500
Mafcury
ilUb'ai
rvv^KW
ug/dacm
ug/daem
NO
NO
1.091
9.333
NO
0 450
NO
Saiantum
ugMaew
NO
ND
Zne
uQAf«c»
tM07
4.500
Fofmaidahyda
ug/dacm
2944.1
NO
292.4
130.0
Acsfaldaltyda
ug/dacm
12SS.2
NO
71.2
28.8
Baiuildaftyda
ug/dtcm
38.156
NO
Acrolaio
ug/dtcm
20141*
NO
SanXM*
ug/dacm
zm
•443
•894
129
' 2S7
' 1«
Phanet
ng/dtcm
. s»
NO
Chlorinatad Phaiwt
fc 1 -n lull f ¦ ¦ ^
Naprnraiane
ng/d»cm
ng/dacm
082,2
171500
NO
NO
Tola) Oioxina
og/d«cm
1,7W
0.560
0.193
T«al Fufana
ng/daem
7.189
1,314
0.484
PCS*
BgWacw
31.60
ChtarolMflMftM
ng/dacm
400.7
Banzfa janthracaiw
ng/d«cm
142.07
29.30
NO
NO
.Ban;(«}pyrana
(iQMaem
NO
NO
20.077
NO
NO
Chrytana
ng/d«em
232.5
2S5.3
¦ NO
NO
iChlofOlOOTI
ng/dacm
NO
NO
NO
NO
j2.3.7.0-TCOO
ng/dacm
MO
NO
IttnaiTCOO
ng/dacm
NO
0.00217
:ioiu«na
ug/d tern
202.10
196.50
NO
23.49
| Hydrogan Chlofida
ppm
NO
10390
7.331
NO: Not Oatactad (i a.. baton* dat action limit)
PGP: Pantacfiloropftanol
Stank* indicaw no data
{1} Total gMKKia nonmanlan* hydroca/Oona w math ana
benzene were lower than in the clean wood tests. PAH, PCBs and chloroform
emissions were below detection limits for both series of tests- Toluene
emissions were measured in the railroad tie tests, but were below detection
in the clean runs. The Northwood Pulpmill and the Blandin Paper Co.
facilities contained the only data found in this study on hydrogen chloride
(HCi) emissions, with the exception of one test program conducted at the
Vicon Pittsfield incinerator (1?). Although the Vicon test summarized in
8-42
-------
this study reportedly was conducted with "PVC-free" wood, chips (from
pallets) and cardboard, the HC1 emissions were almost ten times higher than
the highest of all the other HCl emissions data. The fact that PVC-spiked
MSW was fired in other tests during the same program makes the results of
the "PVC-£r®e" test run suspect. HCl emissions from the Blandin Paper Co.
boiler firing railroad ties were below the level of detection {<0,1 ppm) .
At the Northwood Pulpmill chlorophenol-contaminated test program, HCl
emissions ranged from 3 to 18 ppm.
i.? Environmental Impacts
Environmental impacts due to waste wood combustion emissions were evaluated
fox this study using the following method;
1. Emissions from a hypothetical spreader stoker boiler burning C/D waste wood
and controlled with a high efficiency ESP were developed from the
emissions, wood and ash data compiled for this project.
2. Ambient impacts were estimated with dispersion modeling for two
hypothetical cases: (1) an approximate 15 MW facility with non-GEP stack
height located in relatively flat, rural terrain and {2) a 15 MW facility
with GEP stack located in a valley with some terrain higher than stack
height.
3. Ambient impacts of hazardous air pollutants were compared with short term
iacute) and long term I chronic) exposure levels as established by state
regulations in the project study area.
The spreader stoker with ISP was chosen over other boiler types for this
analysis because of the prevalent use of this combination for moderate to
large size wood power plants. In addition, based on the data, even the best
operated spreader stokers would likely have slightly lower combustion
efficiencies than fluid bed boilers for biomass and wood applications.
Therefore, organic emissions from spreader stokers are conservatively high for
this analysis.
To develop worst-case organic emissions, the emissions database was
partitioned so that data from only the spreader stokers operating under "good"
combustion conditions {i.e., less than 500 ppm carbon monoxide} were used.
The maximum values were used as the maximum short-term emissions, and the
average values as the average annual emissions. For dioxin emissions, all
available data regardless of boiler type and the associated CO concentration
were used to obtain maximum and average values because none of the dioxin data
were obtained from boilers operating under "good" combustion conditions.
Metals emissions were developed by the method discussed in Section 8.6.2 {see
Table 8-11} using conservative assumptions about ash partitioning. The wood
composition data were used for this analysis so that the metals emissions
would be representative of C/D wood combustion. Specifically, the metals when
combusted in wood were conservatively assumed to remain in the fly ash too
metals partitioning to bottom ash) and the metals control efficiency of the
ESP was assumed to be equivalent to the total particulate control efficiency
except for mercury, for which a 30% removal efficiency was assumed. The 95th
percentile wood metals concentrations was used as the basis for the maximum
stack emission rates, and the median values as the basis for average annual
emission rates.
As discussed in Section 8.6.4, the highest HCl data found from this study are
not representative {relatively high HCl levels were measured in a reportedly
"pvc-free" test run at an MSW incinerator). The only other HCl data sources
8-43
-------
were a railroad tie test burn and a chlor©phenol-contaminated wood test burn.
HC1 emissions from the railroad tie test burn. were not detected {<0.1 ppm) and
wood waste spiked with chlorophenol solution is not deemed to be
representative of the burning of C/D wood. Therefore, HC1 emissions were not
evaluated in the ambient impact analysis.
Maximum ambient impacts caused by emissions from the hypothetical facilities
were conservatively estimated using dispersion modeling procedures usually
required by EPA and the states in the study area when permitting new sources.
The two cases were chosen to represent a range of terrain versus stack height
conditions that will have a significant effect on ambient impacts. The
various steps of the modeling procedures are designed to over predict maximum
impacts, accounting for uncertainties in emission rates, stack parameters, and
meteorological conditions through use of conservative modeling assumptions.
Using these modeling procedures, maximum normalized one-hour average and
annual average impacts were determined at .any location surrounding the
hypothetical plants. These normalized values represent the maximum predicted
impact corresponding to an emission rate of one gram per second of any
pollutant. Maximum impacts for each individual pollutant are then calculated
by multiplying the pollutant's emission rate by the normalized impact of
interest.
The one-hour and annual average impacts were compared to regulatory guidelines
obtained from the air quality regulations from several states in the study
area. The state regulations selected for this analysis represent the range of
guideline concentrations in the study area. In general, New York and Vermont
typically have the most stringent guideline concentrations, and the annual
guidelines are more difficult to meet than the short-term guidelines.
The assumptions and calculations used to perform the air impact analysis are
summarized in Table 8-17, The results of the analysis are presented in fables
8-18 and 8-19 for the short-term and annual average impacts, respectively.
As expected, the dispersion modeling case that results in the higher ambient
impact is the one involving the facility situated in a valley (Case II}.
Short-term (one-hour) impacts are seventeen times higher for Case II than for
Case I, the flat terrain situation. Annual average impacts for Case II are
almost three times higher than Case I.
As a result, an exceedance of one state's (New York's} short-term guideline is
predicted for arsenic for the Case II analysis, while no exceedances are
predicted for Case I. Similarly, annual-average impacts from the Case II
scenario are slightly above the guideline concentrations for Ass and Cr, while
no exceedances of annual average guideline concentrations are predicted for
Case I. It should be noted that the total Cr guideline in VT is more than a
thousand times more stringent than other states and of the same order of
magnitude as the hexavalent chromium guideline for other states. Vermont is
most likely applying a health-derived standard for hexavalent chromium to
total chromium emissions.
No exceedances of short-term or annual guideline concentrations are predicted
for any of the organic compounds, even with the conservativeness of the
methods used to develop some of the emission rates and impacts. For example,
it should be noted that the TCDD and HxCDD emissions used for this analysis
are based on a few data points that are one to two orders of magnitude higher
than the bulk of the data. Furthermore, these data are not representative of
boilers operating under good combustion conditions (See Section 8.6.45. It
is, therefore, expected that dioxins emissions would be even further below
guideline concentrations.
8-44
-------
Table 8-17, Assumptions for ambient impact analyses.
Slack Emissions:
Metals: Calculated from construction/demolition wood metals analyses,
(Sea Table 8-11 lor calculations.)
Chromium VI calculated as 5% of Chromium III value.
Manganese & Selenium (not tested for in c/d wood) from database for pm < 0.01 gr/dscf.
Short-term (table 8-18) values are based on the 95thpercentiies.
Annual (table 8-19) values based on the medians.
Organics: Taken from database, spreader stokers with good combustion (CO < 500 ppm), with exception of
dioxins. Alt dioxins data from all bolter types used for analyses.
Short-term values from maximums.
Annual values from averages.
Ambient Impacts:
Case i: Dispersion modeling analyses on 15 MW, non-GEP stack in flat terrain
Stack height; 180 feet
Gas vol. rate: 2068.83 dscf/mtn
Temp; 310 deg. F
Normalized impacts: 1-hour: 11.31 (ug/m3y(g/s)
Annual: 1.131 (ug/m3)/(g/s)
Case II: Dispersion modeling analyses on IS MW, GEP stack in valley with some terrain higher than slack
Stack height: 180 feet „
Gas vol. rate: 53440 dscf/mln
Temp: 300 dog. F
Normalized impacts: 1-hour: 189.8 (ug/m3)/(g/s)
Annual: 3,25 (ug/m3)/(g/s)
Example conversions: {for Arsenic, Case 1,1-hour)
{ug/dscm) In stack —> (g/s) emission rate
61.36 ug/dscm * (1 cu.m/35.31 cu.ft) * (1 g/10*6 ug) * (2068.83 dscf/mln) • (1 min/60 sec) - 0,0000589 g/sec
(g/s) omission rate — > (ug/m3) normalized impact
0,0000599 g/8 * 11.31 (ug/m3)/(g/s) - 0.00068 ug/m3
-------
Table 8-18. Air quality analyses of short-terra (1 hour) ambient impacts.
Maximum
Short-Term
State 1-Hour Gold
elines
Stack
Ambient Impacts
North
New York
Wisconsin
Pollutants
Emissions
Case I
Case 11
Carolina
ug/dscm(l)
ug/m3
ug/m3
ug/m3
ug/m3
ug/m3
Metals:
Aluminum
1000
Arsenic
61,36
0.00068
0.29
0.2
20
Barium
222.99
0.0025
1.1
120
SO
Cadmium
0.92
0.000010
0.0044
0.2
¦'5
Chromium fll
120.52
0.0013
0.58
120
50
Chromium VI
0.1
5
Copper
53.07
0.00059
0.25
240
100
Iron
100
Lead
447.97
0.0049
2.1
15
Manganese
240
Mercury
0.38
4.23E-06
0.0018
' 12
5
Nickel
8.16
0.000090
0.039
1.5
100
Selenium
48
20
Silver
1.46
0.000016
0.0070
10
Titanium
233.24
0.0026
1.1
Zinc
185.01
0.0020
0.89
150
Organics:
Acetaldehyde
390
0.0043
1.9
43000
18000
Benzene
347
0.0038
1.7
30
3200
Formaldehyde
5496
0.061
26
30
120
Phenol
0.0735
8.12E-07
0.00035
950
' 4500
1900
Toluene
15.51
0.00017
0.074
89000
37700
Naphthalene '
321
0.0035
1.5
12000
5000
TCDD
0.002
2.2E-08
9.58E-06
HxCDD
0.0036
4.QE-08
1.72E-05
Benzo[a]pyrene
0.00435
4.8E-08
2.08E-05
Case I: 15 MW, non-GEP stack height, flat terrain •
Case il: 15 MW, GEP stack, height, valley with some terrain higher
than stack
Guidelines: Wisconsin All Wood Ambient Impact Limit 1 hr basis
North Carolina i -Hour Acute Systemic Toxicants
New York Short-term Guideline Concentrations (1-hour)
(i): Corrected to 12% C02.
8-46
-------
Table 8-19, Air quality analyses of annual ambient impacts.
Average
Annual
State Annual Guidelines
Stack
Ambient Impacts
North
New York
Vermont
Pollutants
Emissions
Case 1
Case II
Carolina
ugMscm{1}
ug/m3
ug/m3
ug/m3
ug/m3
ug/rn3
Metals:
Aluminum
Arsentc
3.31
3.66E-06
0.00027
0.00023
0.00023
0.00023
Barium
22.33
0.000025
0.0018
11.9
Cadmium
0.20
2.24E-07
0.000017
0.0055
0.0005
0.00057
Chromium III (2)
7.11
7.86E-06
0.00058
0.1
0.000085
Chromium VI
0.000083
0.00002
Copper
6.90
7.62E-06
" 0.00057
2.4
100
Iron
Lead
47.73
0.000053
0.0039
1.5
1.5
Manganese
31
0.3
Mercury
0.08
8.32E-08
6.17E-06
0.06
0.3
0.144
Nickel
2.03
2.24E-06
; 0.00017
6
0.02
0.0033
Selenium
4.8
4.8
Silver
0.04
4.39E-08
3.26E-06
0.24
Titanium
134.17
0.0001 i
0.011
Zinc
39.01
0.000043
0.0032
50
12
Organics:
Acetaidehyde
165.48
0.00018
0.014
430
1800
Benzene
275.38
0.00030
0.023
0,12
0,12
0.12
Formaldehyde
720.87
0.00080
0.059
0.06
0.08
Phenol
0.0404
4.46E-08
3.31 E-06
9.6
1900
Toluene
15.51
0.000017
0.0013
2000
8930
Naphthalene
133.79
0.0001 s
0.011
120
120
TCDD
0.0003
3.31E-10
2.46 E-08
3.0E-06
3.0E-08
HxCDD
0.00078
8.61 E-10
6.39E-08
7.6E-05
Benzofajpyrene
0.00246
2.72E-09
2.02E-07
3.30E-02
2.00E-03
3.00E-C4
Case I: 15 MW, non-G EP stack height, flat terrain
Case II: 18 MW, GEP stack height, valley with some terrain higher
than stack
Guidelines: North Carolina Annual Carcinogens
New York Annual Guideline Concentrations
Vermont HIV Annual Average
(1): Corrected to 12% C02.
(2): Vermont standard Is for total chromium.
8-47
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The following conclusions can be drawn from this ambient impact analysis;
1. By using conservative assumptions to estimate metal emissions, the
combustion of C/D waste wood may result in exceedances of state guideline
concentrations for As and Or. Reduction in the amount of CCA-treated wood
may be necessary for facilities to meet State guidelines.
2. The combustion of "clean"" wood is not likely to result in guideline
exceedances. As and Cr emissions from "clean" wood combustion are
estimated to be at least one order of magnitude lower than emissions
estimated from C/D wood metals analysis.
3. Emissions of organic compounds, which do not appear to be affected by fuel
composition (see Section 8.6.4), are expected to result in ambient impacts
that meet state guidelines.
4. The topography (e.g., high terrain) of the area surrounding a facility can
significantly affect ambient impacts and the ability of plant emissions
¦ impacts to meet stringent guidelines.
8.8 Bibliography - Chapter 8
Reference No.
in Table 8-1
Booth, R.B., Current BACT and... Achievable Bmiss i on Limi tat i ons 1
Applicable to Wood .Fired Boilers. Energy Systems Association, 1989.
Sassenrath, C. P., P.E., "Air Toxic Emissions from Wood Fired Boilers*, 2
Eureka, CA, in TAPPI Proceedings 1991 Envirorinmental Conference.
Technical Association of the Pulp and Paper Industry, 1991,
Evaluation Test on a Wood Waste Fired Incinerator at Louisiana 3
Pacific Hardboard Plant, Oroville, CA, May 1990, CARB Report C-88-066.
Evaluation Test on a Fluidized Bed Wood Waste Fueled Combustor 4
Located in Central California, February 7, 1990, CARB Report C-87-042.
Evaluation Test on a Wood Waste Fired Incinerator at Pacific Oroville 5
Power, Inc., May 29, 1990, CARB Report C-88-050.
Dunn, Steven, letter from Wisconsin DIE (7/8/91) Engineer 608-267-0566. 6
Santos, Robert, Zurn Industries Letter to Aaron Samson (12/22/89), 7
Energy Division.
Evaluation Test on a Wood Waste Fired Incinerator at Koppers Company, 8
Oroville, CA, 5/29/90, CARB Report C-88-065.
CSC 1990, 1 at o rv Options Draft 9
Final Report, Prepared for Environment Canada, CSC Files 1872
{September, 1990).
NCASI, Potential,, for.,..the.. Emission of Formaldehyde... from. Wood-Residue 10
Pired. Boilers, Technical Bulletin No. 622, January, 1992.
Bryan, Joelle, Letter Sent to CT Donovan Kay 29, 1991, SIT of North 11
Carolina, Department of Environmental Health and Natural Resources.
Wood Tech Permit, May 23, 1991, Commonwealth of Virginia, Department 12
of Air Pollution Control.
8-48
-------
Reference No.
in TabU g-1
Results of the August 12 and 13, 1986, Air Emission Compliance Tests 13
for the Railroad Tie Test Burn on the No, 2 Boiler at the NSP Bay
Front Plant in Ashland, WI.
Emission Test Report GE, Redding Power Plant Received September 29, 14
1989.
Data from 1987, Railroad Tie Test burn, at the Blandin Paper Company, 15
Grand Rapids, MM.
Molloy, Tom, Energy Coordinator, Procter & Gamble Soap Division, 16
The Proctor & Gamble Wood Burning Boiler Project at Port
Ivorv, Staten Island, MY, 1995..,
NYSERDA, Results of the Combustion and Emissions Research Project at 17
the VICON Incinerator Facility in Pittsfield, Massachusetts.
Detailed Report for Test Burn of Chlorophenol Contaminated Wood 18
Wastes at Northwood Pulp Mill, Prince George, B.C., April, 1989.
Results of the April 2-4, 1991 Wood Combustion Emission Study at 19
The Birchwood Lumber and Veneer Plant in Birchwood, WI,
Interpol1 Labs.
Wainwright, Phyllis B. And Michael Y. Aldridg*, A POM Emissions 20
Study for Industrial,. Wood Fired Boilers. N.C. Department of National
Resources and Community Development.
Emissions and Performance Characterization of Industrial/Commercial 21
Blomass Combustion Systems. Draft Final Report, Environmental
Assessment Technologies and Energy Technologies, ORTECH International,
March 29, 1991 for Energy, Mines and Resources Canada.
Combustion and Emission Research on Wood-Refuse Boilers Volume III 22
Part 2 Tabulated Results for Site 1, Canadian Boiler Society,
February, 1985.
Alternative Fuel Firing in an Atmospheric Fluidized-Bed Combustion 23
Boiler, Pinal Report, Electric Power Research Institute, June, 1985.
Results of the April 3-5, 1991 Stat# Air Emission Compliance Tests 24
on the Wood-Fired Boilers at the Birchwood Lumber and Veneer Plant in
Birchwood, Wisconsin, Report Bo. 1-3267C, Intesrpoll Laboratories, Inc.,
July 10, 1991.
Berry, L.E., et al., Investigation of Emissions from Combustion of 25
Urban Waste Wood in Industrial Boilers, the Proctor & Gamble Company,
for Presentation at the 78th Annual Meeting of the Air Pollution
Control Association, June 1985.
Alliance Technologies, Performance Test Report, Stratton Energy 26"
Project, Stratton, ME. CESS Job No. J-1002, Oct. 20, 1989.
Waldron, T., Trimont Engineering Co. letter to Peter Bos, ARS, 27
dated 9/18/91 summarizing compliance test results at Stratton Energy
Project and Craven County Wood Energy Project.
Confidential 28
8-43
-------
Reference No.
in Table 8-1
Permits and Selected Emissions Data for Hew Hampshire Wood. Burning 29
Power Plants, sent by Craig Wright, Ml DES, 1931.
Oglesby, H.S. and. R.0 Blosser, Information on the Sulfur Content of 30
Bark and Its Contribution to SO, Emissions When Burned as a Fuel,
JAPCA, July 1980.
Permits and Test Data from Three Fluidized Bed Boilers in CA: 31
Mendota, U1trapower-Presno, and Thermo Electron- Delano.
Letter from. Clayton Tewksbury of Burlington Electric McNeil Generating 32
Station to ERL, dated Dec. 17, 1987, containing stack test results.
8-50
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JT6CHN,CAL Report data
(Please read inurucitons on the reverie. before completing)
3. RECIPIENT'S ACCESSION-NO.
B. REPORT DATE
October 1996
6. PERFORMING ORGANIZATION CODE
8, PERFORMING ORGANIZATION REPORT NO
10. PROGRAM ELEMENT NO,
11 CONTRACT/GRANT NO.
GR815271 (NYSERDA)
13. TYPE of REPORT and PERIOD COVERED
Final; 3/91-7/92
14. SPONSORING AGENCY CODE
I' REPORT NO "
EPA-600/R-96-119 a
|4. TITI.E AND SUBTITLE
Wood Products in the Waste Stream—Characterization
and Combustion Emissions, Volume 1. Technical
Report
17. ALfTHOR(S) " ~
1 Richard S. Atkins (ERL) and Christine T. Donovan
(CTD Assoc.)
FORMING ORGANIZATION NAME AND ADDRESS
Environmental Risk Limited, 120 Mountain Ave..
I Bloomfield, Connecticut 06002
%J\.Do°ova?r Associates. p-°- Box 5665*
Burlington, Vermont 05402
112. SPONSORING AG6NCV NAME AND ADDRESS
EPA, Office of Research and Development
MSgtefeyg Laboratory
C" McCrillis. Mall Drop 61. 919/
lie. AB^TRA^T—T
tory xaSue?ftatS'et0frh„SrSUl'3 ,°' " "T** °f techni^- Publio policy, and reguU-
bs s±i£? pro1
UofrceIIT OD fe U8e 0f wa3le-"ood materials as a combustion™-
fcaMSaSSrS^r?55^-
—— wrrrsxRsssi-
b»33=SS3H££»
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Pollution
(Wood Wastes
[Processing
Combustion
Emission
(18. DISTRIBUTION statement
Release to Public
EPA Form 2120-1 (S-73)
b-IDENTIFIERS/OPEN ENDED TERMS
Pollution Control
Stationary Sources
c. COSATI Field/Group
19. SECURITY CLASS (T>its Report)
Unclassified
13 B
11L
13 H
2 IB
14G
21. NO. OF PAGES
308
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