United States
                    Environmental Protection
                    Agency	
National Risk Management
Research Laboratory
Research Triangle Park, NC 27711
                   Research and Development
EPA/600/SR-96/119
November 1996
^» EPA      Project Summary
                   Wood  Products  in the  Waste
                   Stream-Characterization  and
                   Combustion  Emissions
                    Richard S. Atkins and Christine T. Donovan
                     Waste wood is wood separated from
                   a solid-waste stream  and  processed
                   into a uniform-sized product that is re-
                   used for other purposes such as fuel.
                   As an alternative to the combustion of
                   fossil fuels, it has raised concerns that,
                   if it is "contaminated" with paints, res-
                   ins, preservatives,  etc., unacceptable
                   environmental impacts may be gener-
                   ated during combustion. Given the  dif-
                   ficulty of separating contaminated ma-
                   terial from waste wood and the large
                   energy potential existing  in  the  re-
                   source, it is important to identify pos-
                   sible problems associated with con-
                   taminated waste-wood combustion.
                   This project:
                     • Identifies the quantity and quality
                      of waste wood;
                     • Summarizes regulatory issues af-
                      fecting the processing and com-
                      bustion of waste wood for energy;
                     • Characterizes waste-wood process-
                      ing and combustion facilities;
                     • Characterizes representative waste-
                      wood samples; and
                     • Collects  and analyzes emissions
                      data from operating combustion fa-
                      cilities.
                     Types of waste wood described in-
                   clude pallets; construction and demoli-
                   tion waste; wood treated with paints or
                   stains; wood containing glues, binders,
                   or resins; wood containing plastics or
                   vinyl wood treated  with preservatives
                   such as creosote, chloropentaphenol,
                   and chromium copper arsenate;  and
                   wood treated with pesticides or fungi-
                   cides.
                     This study,  completed  in mid-1992,
                   describes research of technical, public
                   policy,  and regulatory issues that af-
 fect the processing and combustion of
 waste wood for fuel.
  The  report provides environmental
 regulators, project developers, and oth-
 ers with data to make informed deci-
 sions on the use of waste-wood mate-
 rials as a combustion resource. Poten-
 tial environmental problems and solu-
 tions were identified.
  One project result was the identifica-
 tion  of combustion-system operating
 parameters and air pollution control
 technologies that can minimize emis-
 sions of identified air and solid-waste
 contaminants from the combustion of
 waste wood.
  This Project Summary was developed
 by  EPA's  National Risk Management
 Research  Laboratory's, Air Pollution
 Prevention  and Control Division,  Re-
 search Triangle Park, NC, to announce
 key  findings of the research project
 that is fully documented in a separate
 report of the same title (see Project
 Report ordering information at back).

 Introduction
  This  report 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, indus-
 trial,  agricultural,  construction, and demo-
 lition activities. Treated wood is commonly
 referred to as "urban," "recycled," "treated,"
 "dirty," and/or "demolition" wood. "Clean"
 wood is a by-product of harvesting activi-
 ties 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 affect

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the environmental  permitting of facilities.
Each state or province has developed defi-
nitions for different wood fuels, or classi-
fies combustion facilities according to the
type of wood fuel burned. For this report,
wood-fuel types are divided into "clean" or
"treated" wood. "Clean" wood is untreated
and uncontaminated natural wood.
  In this report, wood is referred  to  as
"waste wood"  when  it  is  in  its prepro-
cessed form and  as "processed wood"
when  it has been prepared for fuel.

Federal, State, and Provincial
Regulations
  The project  (1)  reviewed existing fed-
eral, state, and provincial air, solid waste
and energy policies,  and regulations that
relate to waste-wood processing and com-
bustion facilities; (2) identified major trends
in  policies that affect the processing and
use of waste wood  for energy;  and (3)
investigated ash disposal from waste-wood
combustion facilities.
  Major air quality regulatory  issues that
affect waste-wood combustion facilities in-
clude:
  • Regulatory implications for permitting
    a "treated" or a  "clean" wood com-
    bustion 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  exist-
    ing wood-combustion facilities.

Types and Amounts of Waste
Wood A vailable for Fuel
  This study compiled  data on the types
and amounts of waste wood currently gen-
erated 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 harvest-
ing, municipal, commercial, industrial, ag-
ricultural, construction, and demolition ac-
tivities. 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,  for-
estry  and wood  use  experts, solid-waste
managers, forest products industries, and
published research on forestry and waste-
wood  resources is  included.

Composition of Waste Wood
  The study  identified specific  types of
treated waste-wood materials that are com-
monly  found in  solid-waste streams  in-
cluding:
  • Wood  products manufactured with
    glues, binders, or resins, such as struc-
    tural 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 pre-
    servatives such as creosote, pentachlo-
    rophenol, or chromium copper  arsen-
    ate (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  scien-
tists, and others. A  summary of common
wood  products and  the levels  and types
of non-wood contaminants is provided.
  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.

Waste-Wood Processing
Facilities
  The study investigated facilities that col-
lect, sort, and  process  waste wood  for
fuel. Six processing  facilities in the U.S.
and Canada were visited.  In addition, pro-
cessing equipment  manufacturers, solid-
waste regulators, and facility owners and
operators that were  not visited were inter-
viewed.
  Research focused on investigating regu-
latory 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 ma-
jor  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 contin-
gent on many factors including the eco-
nomic and  regulatory climate that affects
the types of waste wood available to pro-
cessing facilities; ways in which recycling
and solid-waste  management  authorities
permit  a processing facility;  and the size
and specifications of markets that use pro-
cessed 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 in-
spection  and  enforcement of unaccept-
able materials prior to  processing is  an
important step in achieving and maintain-
ing the quality and specifications required
for fuel and other end-use products.

Waste-Wood Combustion
Facilities
   Combustion facilities  that  burn,  or  in-
tend 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,
pollution control equipment used, and stack
emissions and ash characteristics were
collected.  Research techniques included
surveying commercial and industrial wood
energy facilities; visiting two  combustion
facilities in the  U.S. and Canada; complet-
ing telephone  interviews with plant engi-
neers, equipment manufacturers,  and air-
quality regulators; and reviewing published
research  about the performance of vari-
ous wood-combustion systems.
   The  study  identified  key  issues  con-
cerning  fuel specifications and procure-
ment, fuel delivery and feeding equipment,
and  furnace and boiler  designs for com-
bustion facilities that use processed wood
for all or part of their feedstock. The study
focused on utility-scale power plants that
burn processed wood exclusively for elec-
trical generation,  and industrial facilities
that burn processed wood to produce ther-
mal and/or electrical energy.  In particular,
the project team investigated the issues
that 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 famil-
iarity of state,  provincial, or local  regula-
tory authorities with waste-wood combus-
tion technologies and facilities.

Chemical and Physical
Properties of Waste Wood and
Its Ashes
   The chemical and physical  properties of
waste woods and the ashes produced from
their combustion were evaluated. There is
limited  information available in the techni-
cal 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

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increased interest in using waste wood to
produce energy,  it is important to under-
stand its properties to predict the environ-
mental impact from its burning.
  The type  of  information  gathered  for
this study is needed to evaluate the emis-
sion 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 develop-
ers, regulators, and others.
  This study used random sampling tech-
niques to  obtain waste wood and  ash
samples from six waste-wood processing
and  two  combustion  facilities that  em-
ployed various  processing and combus-
tion 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 also by laboratory ashing the
collected waste-wood samples.
  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  in-
stances, ash samples were also collected
and studied. The following types of homo-
geneous waste woods were collected and
analyzed:
  • plywood
  • CCA pressure-treated wood
  • particle board
  • creosote-treated wood
  • furniture scraps
  • laminated wood

Environmental Impacts of
Waste-wood Combustion - Air
  Emissions of  heavy metals, sulfur, and
chloride from the  combustion of waste
wood in boilers  can be  approximated us-
ing wood and ash concentration  data de-
veloped for this study.  These data, and
conservative observations about partition-
ing these compounds  between bottom and
fly ash, can be used to estimate air emis-
sions. Worst case assumptions about the
partitioning (e.g., 100% of metals are con-
tained  in  the fly  ash)  can be used  for
overestimates of emission rates; however,
emissions  of organic compounds cannot
be estimated from wood and  ash  compo-
sition data.
  Actual  emissions data from testing ex-
isting wood boilers have been compiled to
supplement the wood and ash concentra-
tion data gathered for  this study. While
emissions data for criteria pollutants such
as particulate matter, nitrogen oxides, car-
bon 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 pollut-
ants (HAPs) by most state  agencies.
  In the absence of HAP emissions data
for wood  boilers, regulators  have  used
test data from residential wood combus-
tion appliances to quantify emissions. Al-
though these data may be useful in identi-
fying the  types of pollutants that may be
products  of wood combustion, the emis-
sion rates from industrial wood-fired boil-
ers are significantly lower due to  the dif-
ferences  in  combustor design, combus-
tion efficiencies, and operating conditions.
The overall  objective of compiling emis-
sions data for this project,  therefore,  was
to summarize  available HAP emissions
data that are more applicable to commer-
cial or  industrial wood boiler facilities.

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Richard S. Atkins is with Environmental Risk Limited, Bloomfield, CT 06002 and Christine
  T.  Donovan is with C.  T. Donovan Associates, Inc.,  Burlington,  VT 05402.
Robert C. McCrillis is the EPA Project Officer (see below).
The complete report consists of two volumes, entitled "Wood Products in the Waste Stream-
  Characterization and Combustion Emissions."
  Volume 1. "Technical Report," (Order No. PB93-198950; Cost:  $49.00, subject to
  change).
  Volume 2.  "Appendices," (Order No. PB93-198968; Cost: $28.00, subject to change).
The above reports will be available only from:
        National Technical Information Service
        5285 Port Royal Road
        Springfield, VA22161
        Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
        Air Pollution Prevention and Control Division
        National Risk Management Research Laboratory
        U.S. Environmental Protection Agency
        Research Triangle Park, NC 27711
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268

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