The Impact of Municipal Solid Waste Management On

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<ul><li><p>Weitz et al.</p><p>1000 Journal of the Air &amp; Waste Management Association Volume 52 September 2002</p><p>ISSN 1047-3289 J. Air &amp; Waste Manage. Assoc. 52:1000-1011</p><p>Copyright 2002 Air &amp; Waste Management Association</p><p>TECHNICAL PAPER</p><p>ABSTRACTTechnological advancements, environmental regulations,and emphasis on resource conservation and recovery havegreatly reduced the environmental impacts of municipalsolid waste (MSW) management, including emissions ofgreenhouse gases (GHGs). This study was conducted usinga life-cycle methodology to track changes in GHG emis-sions during the past 25 years from the management ofMSW in the United States. For the baseline year of 1974,MSW management consisted of limited recycling, combus-tion without energy recovery, and landfilling without gascollection or control. This was compared with data for 1980,1990, and 1997, accounting for changes in MSW quantity,composition, management practices, and technology. Overtime, the United States has moved toward increased recy-cling, composting, combustion (with energy recovery) andlandfilling with gas recovery, control, and utilization. Thesechanges were accounted for with historical data on MSWcomposition, quantities, management practices, and tech-nological changes. Included in the analysis were the ben-efits of materials recycling and energy recovery to the extent</p><p>that these displace virgin raw materials and fossil fuel elec-tricity production, respectively. Carbon sinks associatedwith MSW management also were addressed. The resultsindicate that the MSW management actions taken by U.S.communities have significantly reduced potential GHGemissions despite an almost 2-fold increase in waste gen-eration. GHG emissions from MSW management were es-timated to be 36 million metric tons carbon equivalents(MMTCE) in 1974 and 8 MMTCE in 1997. If MSW werebeing managed today as it was in 1974, GHG emissionswould be ~60 MMTCE.</p><p>INTRODUCTIONSolid waste management deals with the way resourcesare used as well as with end-of-life deposition of materi-als in the waste stream.1 Often complex decisions aremade regarding ways to collect, recycle, transport, anddispose of municipal solid waste (MSW) that affect costand environmental releases. Prior to 1970, sanitary land-fills were very rare. Wastes were dumped and organicmaterials in the dumps were burned to reduce volume.Waste incinerators with no pollution controls were com-mon.1 Today, solid waste management involves technolo-gies that are more energy efficient and protective ofhuman health and the environment. These technologi-cal changes and improvements are the result of decisionsmade by local communities and can impact residentsdirectly. Selection of collection, transportation, recycling,treatment, and disposal systems can determine the num-ber of recycling bins needed, the day people must placetheir garbage at the curb, the truck routes through resi-dential streets, and the cost of waste services to house-holds. Thus, MSW management can be a significant issuefor municipalities.</p><p>The Impact of Municipal Solid Waste Management onGreenhouse Gas Emissions in the United States</p><p>Keith A. WeitzCenter for Environmental Analysis, RTI, Research Triangle Park, North CarolinaSusan A. ThorneloeAir Pollution Prevention and Control Division, Office of Research and Development, U.S. EnvironmentalProtection Agency, Research Triangle Park, North CarolinaSubba R. Nishtala, and Sherry YarkoskyCenter for Environmental Analysis, RTI, Research Triangle Park, North CarolinaMaria ZannesIntegrated Waste Services Association, Washington, DC</p><p>IMPLICATIONSTechnology advancements and the movement toward in-tegrated strategies for MSW management have resultedin reduced GHG emissions. GHG emissions from MSWmanagement would be 52 MMTCE higher today if oldstrategies and technologies were still in use. Integratedstrategies involving recycling, composting, waste-to-en-ergy combustion, and landfills with gas collection andenergy recovery play a significant role in reducing GHGemissions by recovering materials and energy from theMSW stream.</p></li><li><p>Weitz et al.</p><p>Volume 52 September 2002 Journal of the Air &amp; Waste Management Association 1001</p><p>MSW management is also an issue of global signifi-cance. The MSW management decisions made by may-ors, county executives, and city and county councils andboards can impact the release of greenhouse gas (GHG)emissions that contribute to global climate change. GHGemissions can trap heat in the atmosphere and lead towarming the planet and changing its weather. Accordingto the latest U.S. Environmental Protection Agency (EPA)inventory of GHG emissions, the waste management sec-tor represents ~4% of total U.S. anthropogenic GHG emis-sions (i.e., 260 out of 6750 teragrams of CO2 equivalents).</p><p>2</p><p>Landfills are the largest anthropogenic source of CH4 inthe United States and represented ~90% of GHGs fromthe waste sector in 1999.2 Emissions of CH4 result fromthe decomposition of biodegradable components in thewaste stream such as paper, food scraps, and yard trim-mings. The potential for global climate change caused bythe release of GHGs is being debated both nationally andinternationally. Options for reducing GHG emissions arebeing evaluated. MSW management presents potentialoptions for GHG reductions and has links to other sec-tors (e.g., energy, industrial processes, forestry, and trans-portation) with further GHG reduction opportunities.</p><p>This study was conducted for the U.S. Conference ofMayors through funding provided by the Integrated WasteServices Association. It examined the effect of local MSWmanagement decisions on GHG emissions during the past25 years. The scope of the study included all activities thatplay a role in MSW management, from the point at whichthe waste is collected to its ultimate disposition. Theseactivities include MSW collection, transport, recycling,composting, combustion (with and without energy recov-ery), and landfilling (with and without gas collection andenergy recovery). The life-cycle environmental aspects offuel and electricity consumption were also included, as wellas the displacement of virgin raw materials through recy-cling and the displacement of fossil fuel-based electricalenergy through energy recovery from MSW. The GHGemissions studied in this analysis were CO2 and CH4. OtherGHG emissions such as perfluorocarbons (PFCs) and N2Owere not included, primarily because of limitations in avail-able data. Carbon sinks associated with MSW managementwere evaluated, and results were presented with and with-out carbon sinks included.</p><p>The life cycle of waste is often referred to as a journeyfrom cradle to grave (i.e., from when an item is put on thecurb or placed in a dumpster to when value is restored bycreating usable material or energy, or the waste is trans-formed into emissions to water or air or into inert materialplaced in a landfill).3 Methodologies that provide for a moreholistic approach toward evaluating the operations withinwaste management systems that are interconnected beganto be introduced in 1995.4 The methodology used in this</p><p>study tracks the material and energy flows from cradle tograve. Figure 1 provides an overview of the life-cycle flowdiagram of materials in MSW from cradle to grave that wereincluded in this study.5</p><p>The boundaries for this study include unit processesassociated with waste management, including productionand consumption of energy, extraction of raw materials,transport, collection, recycling/composting, combustion,and landfilling. The waste to be managed is dictated bythe quantity and composition generated in the UnitedStates in the years studied. The net energy consumptionand environmental releases associated with managing MSWare calculated, including offsets for (1) energy producedfrom waste combustion and landfill gas utilization and (2)energy and virgin resources that are conserved as a resultof recycling programs. The offsets and environmental re-leases are specific to the different types of materials withinthe waste stream, which includes the different types of alu-minum, glass, paper, plastics, and steel in MSW.6</p><p>The technical analysis for this study was conductedby RTI International under the direction of EPAs Officeof Research and Development (ORD) using data and acomputer-based decision support tool (referred to hereaf-ter as the MSW DST) developed through a cooperativeagreement between EPA/ORD and RTI.7,8 Representativesfrom EPA, RTI, Integrated Waste Services Association, U.S.Conference of Mayors, Solid Waste Association of NorthAmerica, Environmental Industry Associations, WasteManagement Inc., and ICF Consulting worked coopera-tively to review this analysis.</p><p>METHODOLOGYTo calculate GHG emissions from MSW management,data were collected on the breakdown of MSW by ma-terial for 1974, 1980, 1990, and 1997. The most recentyear for which comprehensive information is availableis 1997.9 The oldest available data for MSW manage-ment practices were from 1974.10 A review of techno-logical changes and management practices wasconducted. Since 1974, MSW management in theUnited States is much more complex than simply haul-ing the waste to a dump. Advances in technology, inaddition to federal and state regulations, have resultedin substantial investments in residential and nonresi-dential infrastructure for collecting, transporting, andprocessing of recycling and composting, and for dis-posal techniques.1 In a 1995 study of U.S. communi-ties, substantial diversity in system complexity wasfound, reflecting differences in geographical locations,types and quantities of solid waste managed, operationaland ownership structures, energy use, and environmen-tal safety regulations and guidelines.11 This is quite dif-ferent from how waste was being managed in the 1970s.</p></li><li><p>Weitz et al.</p><p>1002 Journal of the Air &amp; Waste Management Association Volume 52 September 2002</p><p>The following is a description of four U.S. communitiesusing information from the report published in 1995 toillustrate the diversity and complexity that exists.11</p><p>Complexity of MSW ManagementSystems in the United States</p><p>The Minnesota Waste Management Act was passed in 1980.Since then, substantial changes have occurred throughoutthe United States. In Minnesota during the study, systemcomponents included collection and transport of curbside/alley residential and commercial waste, recyclables, yardwaste collection services, drop-off sites, and transfer sta-tions. There is also a mass-burn MSW combustion facility(with energy recovery), three refuse-derived fuel (RDF) wasteprocessing facilities, and a private processing facility forrecyclables. Of the MSW being processed, 15% is recycledand 11% (i.e., yard waste) is composted. Regional and out-of-state landfills are used for the disposal of residues, non-processible waste, and ash.12</p><p>In Palm Beach County, FL, system components includecollection and transport of curbside MSW, recyclables, andyard waste. There are also drop-off sites and transfer stations.The system also includes four transfer stations, MSW com-bustion (with energy recovery), an RDF processingfacility, a ferrous processing facility that produces a market-able product from recovered ferrous, a materials recovery</p><p>facility (MRF) that processes recyclables, and a co-composting facility that processes sewage sludge mixed withsource-separated yard waste. About 19% of the MSW is re-covered for recycling programs. Compost is processed inan enclosed building using an aerated, agitated bay tech-nology. Only residual waste and ash are sent to landfills.13</p><p>In 1992, Scottsdale, AZ, system components includedcollection and transport of curbside MSW and on-call col-lection of corrugated moving boxes. There were also drop-off sites for MSW and recyclables. Less than 1% of theMSW was recovered for recycling. More than 92% of theMSW was transported to three unlined landfills.14</p><p>In Seattle, WA, the system components included col-lection and transport of curbside MSW, yard waste, andrecyclables. There were also two transfer stations, twoMRFs, and a source-separated yard waste compost facil-ity. The compost facility is in a rural area and is an open-air facility. It uses large windrow piles that are turned andaerated by a windrow turner to process the compost. Re-sidual waste is hauled by rail to a lined landfill. At thetime of the study, 13% of yard waste was composted, and15% of MSW was recycled.15 Because of the closing of twocity-operated landfills in the late 1980s, the city decidedto pursue an aggressive waste reduction program and seta recycling goal of 60% of the waste stream by 1998. In1996, Seattle was approaching this goal, diverting 49% of</p><p>Figure 1. Diagram of material and energy life-cycle flows and the associated GHG sources and sinks.5</p></li><li><p>Weitz et al.</p><p>Volume 52 September 2002 Journal of the Air &amp; Waste Management Association 1003</p><p>its residential waste stream, 48% of its commercial wastestream, and 18% of materials delivered to drop-off sites.The recyclable materials were collected and processed attwo private facilities using conveyors, trommel and discscreens, magnetic separation, air classification, balers, andhand-sorting to separate materials.16</p><p>Across the United States, technological advancementsin collection, transport, recycling/composting, combustion,and landfilling are helping to minimize potential impactsto human health and the environment. For example, fed-eral and state requirements are in place under the ResourceConservation and Recovery Act of 1976 and the Clean AirAct. For the baseline year of this study, waste was typicallyhauled to dumps with nuisances associated with odor, air-born litter, occurrence of disease vectors such as rats, mice,and flies, as well the generation of landfill gas emissionsand leachate resulting from the decomposition of biode-gradable waste and rainwater filtering through the landfilledwaste.17,18 Todays landfills are modern sanitary landfillsin response to state and federal requirements for liners,leachate collection and treatment, and prevention of land-fill gas explosions.19,20 In 1996, New Source PerformanceStandards and Emission Guidelines were promulgated re-quiring that landfill gas be collected and controlled atlarge landfills (&gt;2.5 million tons of waste).21 The first land-fill gas-to-energy recovery project began operating in1981.22 Now there are 300 landfill gas-to-energy projectsproducing electricity or steam.23</p><p>MSW combustion has also gone through substantialchanges. In the 1970s, MSW was directly combusted with-out energy recovery and with little or no pollution con-trol. Currently, there are 102 facilities in the United Statesthat combust waste to generate steam or electricity. In thesecommunities, the average recycling rate is 33%, which is5% greater than the national average.24 These facilities alsohave heat recovery, electricity production, and the highestlevels of pollution control. Results from a recent EPA in-ventory of these facilities has shown that emissi...</p></li></ul>


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