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 ------- 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 ------- 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. ------- 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 Official Business Penalty for Private Use $300 BULK RATE POSTAGE & FEES PAID EPA PERMIT NO. G-35 EPA/600/SR-96/119 ------- |