This report describes individual waste management methods, such as sanitary land filling, composting, recycling, or combustion. Those methods are referred to here as "options" or as "technologies." A data base has been constructed to make the data on individual technologies accessible. To determine the effects of combining individual technologies, this report also presents analyses of selected combinations of waste management technologies, together with choices concerning collection and transport of waste. Those combinations are referred to here as "integrated strategies." In addition, the data base allows users to estimate the energy and emissions for strategies consisting of any combination of individual technologies.

Objectives

The overall objective of the study summarized in this report was to gather data on waste management technologies and to provide a basis for comparison of various alternatives for managing MSW. The specific objectives of the study were to:

1. 1. Compile detailed data for existing waste management technologies on costs, environmental releases, energy requirements and production, and coproducts such as recycled materials and compost.
2. 2. Identify missing information necessary to make energy, economics, and environmental comparisons of various MSW management technologies, and define needed research that could enhance the usefulness of the technology.
3. 3. Develop a data base that can be used to identify the technology that best meets specific criteria defined by a user of the data base.

The first step in attaining the study objectives was to compile publicly available information on MSW management technologies. The following major MSW technologies were selected for consideration:

• Landfill with gas recovery and use(3)
  
• Mass burning, including steam and/or electricity production
  
• Refuse-derived fuel (RDF) production, with subsequent utilization of the fuel for direct combustion to produce heat for steam or electricity
  
• Materials collection, separation, and recycling, which includes curbside collection of reusable materials as well as separation at material recovery facilities(MRFs)
  
• Composting

• Anaerobic digestion(4)
  
• Cofiring of RDF with coal
  
• Gasification/pyrolysis(4)

• Technical features
  
• Energy requirements and production
  
• Environmental releases
  
• Capital and operating costs.

Methodology

Life-Cycle Analysis

In compiling data about energy requirements and environmental releases, a life-cycle assessment framework was used. That approach generally followed life-cycle assessment practice as described, for example, by the Society of Environmental Toxicology and Chemistry (SETAC, 1991).

The MSW life cycle was defined as extending from the waste's origin-the point at which the waste is placed by the generator (a household, commercial establishment, or institution) for collection by a municipality (e.g., at the curb for household waste), through any and all transportation and processing operations, to its final disposition, such as through recycling, combustion, and landfilling operations. The MSW technologies that were investigated can be combined or integrated in several ways, as illustrated in Figure 1.1. For each operation(5), data describing net energy balances and environmental releases were compiled and converted to a common basis of one ton of MSW placed for collection. These data can be combined to determine the overall net energy balances and environmental releases for a given integrated MSW management strategy.

Data Consistency

Data on energy requirements and recovery and on emissions to air, water, and land are reported on a consistent basis in pounds per ton of MSW processed. That format was chosen to simplify comparisons between the various approaches to MSW disposal.

Conversion of emissions data to that uniform basis is complicated because emissions are usually reported in terms of concentrations. For example, sources may provide data in nano-grams of dioxin per cubic meter of stack gas without mentioning the quantity of MSW fuel fed to the facility, the stack gas flow rates, or even indirect measures of those quantities. Thus, in some cases it was necessary to make assumptions about average MSW consumption and heating value to convert emissions data. The assumptions have undoubtedly introduced systematic errors leading to uncertainties of perhaps +30% in the emissions estimates given here. The range of those uncertainties, however, is far smaller than the range of emissions estimates reported in the literature. In actual process tests, individual measurements for the same equipment sometimes differ from each other by factors of up to 10.

Table 1.1
MORE COMMONLY USED STRATEGIES PRESENTED IN THE DATA BASE

    1     Collection and transportation of MSW in a packer truck

          Landfilling the MSW


    2     Collection and transportation of MSW in a packer truck

          Mass burning the MSW

          Ferrous metal recovery

          Landfilling ash in a monofill


    3     Collection and transportation of MSW in a packer truck

          On-site separation of recyclables (in a mixed-waste MRF)
   
          Mass burning the remaining MSW

          Landfilling ash in a monofill


    4     Collection and transportation of MSW in a packer truck

          RDF preparation and metal recovery

          Combustion of RDF

          Landfilling of RDF discards

          Landfilling ash in a monofill


    5     Collection and transportation of MSW in a packer truck

          Collection and transportation of curbside-separated yard waste
 
          Composting the collected yard waste in windrows

          Landfilling the MSW


    6     Collection and transportation of MSW in a packer truck

          Collection and transportation of curbside-separated recyclables in a multi-compartment truck
  	
          MRF operations

          Landfilling the remaining MSW and MRF rejects


    7     Collection and transportation of MSW in a packer truck

          Collection and transportation of curbside-separated recyclables
          in a multi-compartment truck

          MRF operations and remanufacturing the collected materials

          Mass burning the remaining MSW

          Combustion or landfilling MRF rejects

          Landfilling ash in a monofill


    8     Collection and transportation of MSW in a packer truck

          Collection and transportation of curbside-separated recyclables
          in a multi-compartment truck

          MRF operations

          RDF preparation and metal recovery

          Combustion of the RDF

          Landfilling RDF and MRF rejects

          Landfilling ash in a monofill


    9     Collection and transportation of MSW in a packer truck

          Collection and transportation of curbside-separated recyclables
          in a multi-compartment truck

          MRF operations and remanufacturing the collected materials

          RDF preparation and metal recovery

          Composting of RDF

          Landfilling RDF, MRF, and compost rejects


    10    Collection and transportation of MSW in a packer truck

          Collection and transportation of curbside-separated recyclables
          in a multi-compartment truck

          Collection and transportation of curbside-separated yard
          waste in a packer truck

          MRF operations

          Yard waste composting

          Landfilling the remaining MSW


    11    Collection and transportation of MSW in a packer truck

          Collection and transportation of curb-side recyclables
          in a multi-compartment truck

          Collection and transportation of curb-side separated yard
          waste in a packer truck

          MRF operations

          Yard waste composting

          Mass burning the remaining MSW

          Combustion or landfilling the MRF rejects

          Landfilling the ash in a monofill

Figure 1.1
COMMONLY USED TECHNOLOGY OPTIONS FOR MUNICIPAL SOLID WASTE MANAGEMENT

Click here to expand figure.

Data Quality

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