Integrated waste management (IWM) can be defined as the selection and application of suitable techniques, technologies, and management programs to achieve specific waste management objectives and goals. Because numerous state and federal laws have been adopted, IWM is also evolving in response to the regulations developed to implement the various laws. The EPA has identified four basic management options (strategies) for IWM: (1) source reduction, (2) recycling and composting, (3) combustion (waste-to-energy facilities), and (4) landfills. As proposed by the EPA, these strategies are meant to be interactive, as illustrated in Figure 3.1a. It should be noted that some states have chosen to consider the management options in a hierarchical order, as depicted in Figure 3.1b. For example, recycling can only be considered after all that can be done to reduce the quantity of waste at the source has been done. Similarly, waste transformation is only considered after the maximum amount of recycling has been achieved. Further, the combustion (waste-to-energy) option has been replaced with waste transformation in California and other states. Interpretation of the IWM hierarchy will, most likely, continue to vary by state. The management options that comprise the IWM are considered in the following discussion. The implementation of IWM options is considered in the remaining sections of this chapter.2
The focus of source reduction is on reducing the volume and/or toxicity of generated waste. Source reduction includes the switch to reusable products and packaging, the most familiar example being returnable bottles. However, legislated
bottle bills only result in source reduction if bottles are reused once they are returned. Other good examples of source reduction are grass clippings that are left on the lawn and never picked up and modified yard plantings that do not result in leaf and yard waste. The time to consider source reduction is at the product/process design phase.
Source reduction can be practiced by everybody. Consumers can participate by buying less or using products more efficiently. The public sector (government entities at all levels: local, state, and federal) and the private sector can also be more efficient consumers. They can reevaluate procedures that needlessly distribute paper (multiple copies of documents can be cut back), require the purchase of products with longer life spans, and cut down on the purchase of disposable products. The private sector can redesign its manufacturing processes to reduce the amount of waste generated in the manufacturing process. Reducing the amount of waste may require closed-loop manufacturing processes and the use of different raw materials and/or different production processes. Finally, the private sector can redesign products by increasing their durability, substituting less toxic materials, or increasing product effectiveness. However, while everybody can participate in source reduction, it affects how people go about their business, something that is difficult to mandate through regulation without getting mired in the tremendous complexity of commerce.
Source reduction is best encouraged by making sure that the cost of waste management is fully internalized. Cost internalization means pricing the service so that all of the costs are reflected. For waste management, the costs that need to be internalized include pickup and transport, site and construction, administrative and salary, and environmental controls and monitoring. It is important to note that these costs must be considered, whether the product is ultimately managed in a landfill, combustion, recycling facility, or composting facility. Regulation can aid cost internalization by requiring product manufacturers to provide public disclosure of the costs associated with these aspects of product use and development.2
Recycling is perhaps the most positively perceived and doable of all the waste management practices. Recycling will return raw materials to market by separating reusable products from the rest of the municipal waste stream. The benefits of recycling are many. Recycling saves precious finite resources, lessens the need for mining of virgin materials—which lowers the environmental impact for mining and processing—and reduces the amount of energy consumed and the process carbon footprint. Moreover, recycling can help stretch landfill capacity. Recycling can also improve the efficiency and ash quality of incinerators and composting facilities by removing noncombustible materials, such as metals and glass.
Recycling can also cause problems if it is not done in an environmentally responsible manner. Many Superfund sites are what is left of poorly managed recycling operations. Examples include deinking operations for newsprint, waste oil recycling, solvent recycling, and metal recycling. In all of these processes, toxic contaminants that need to be properly managed are removed. Composting is another area of recycling that can cause problems without adequate location controls. For example, groundwater can be contaminated if grass clippings, leaves, or other yard wastes that contain pesticide or fertilizer residues are composted on sandy or other permeable soils. Air contamination by volatile substances can also result.
Recycling will flourish where economic conditions support it, not just because it is mandated. For this to happen, the cost of landfilling or resource recovery must reflect its true cost and must be at least $40 to $50 per ton or higher (2008 dollars). Successful recycling programs also require stable markets for recycled materials. Examples of problems in this area are not hard to come by; a glut of paper occurred in Germany in the 1984 to 1986 time frame due to a mismatch between the grades of paper collected and the grades required by the German papermills. Government had not worked with enough private industries to find out whether the mills had the capacity and equipment needed to deal with low-grade household newspaper. In the United States, a similar loss of markets has occurred for paper, especially during the period from 1994 through 1997. Prices have dropped to the point where it actually costs money to dispose of collected newspapers in some parts of the country.
Stable markets also require that stable supplies are generated. This supply-side problem has been problematic in certain areas of recycling, including metals and plastics. Government and industry must work together to address the market situation. It is critical to make sure that mandated recycling programs do not get too far ahead of the markets.
Even with a good market situation, recycling, and composting will flourish only if they are made convenient. Examples include curbside pickup for residences on a frequent schedule and easy drop-off centers with convenient hours for rural communities and for more specialized products. Product mail-back programs have also worked for certain appliances and electronic components.
Even with stable markets and convenient programs, public education is a critical component for increasing the amount of recycling. At this point, the United States must develop a conservation, rather than a throwaway, ethic, especially in light of the current energy crisis (2008). Recycling presents the next opportunity for cultural change. It will require us to move beyond a mere willingness to collect our discards for recycling. That cultural change will require consumers to purchase recyclable products and products made with recycled content. It will require businesses to utilize secondary materials in product manufacturing and to design new products for easy disassembly and separation of component materials.2
The third of the IWM options (see Figure 3.1) is combustion (waste-to-energy). Combustion facilities are attractive because they do one thing very well; they reduce the volume of waste noticeably, up to ninefold. Combustion facilities can also be used to recover useful energy, either in the form of steam or in the form of electricity. Volume reduction alone can make the high capital cost of incinerators attractive when landfill space is at a premium or when the landfill is distant from the point of generation. For many major metropolitan areas, new landfills must be located increasingly far away from the center of the population. Moreover, incinerator bottom ash has a promise for reuse as a building material. Those who make products from cement or concrete may be able to utilize incinerator ash.
The major constraints of incinerators are their cost, the relatively high degree of sophistication needed to operate them safely and economically, and the fact that the public is very skeptical concerning their safety. The public is concerned about both stack emissions from incinerators and the toxicity of ash produced by incinerators. The EPA has addressed both of these concerns through the development of new regulations for solid waste combustion (waste-to-energy) plants and improved landfill requirements for ash. These regulations will ensure that well-designed, well-built, and well-operated facilities will be fully protective from the health and environmental standpoints.2
Landfills are the one form of waste management that nobody wants but everybody needs. There are simply no combinations of waste management techniques that do not require landfilling to make them work. Of the four basic management options, landfills are the only management technique that is both necessary and sufficient. Some wastes are simply not recyclable, because they eventually reach a point where their intrinsic value is dissipated completely so they no longer can be recovered, and recycling itself produces residuals, and is no longer cost-effective and or energy efficient.
The technology and operation of a modem landfill can assure protection of human health and the environment. The challenge is to ensure that all operating landfills are designed properly and are monitored once they are closed. It is critical to recognize that today's modern landfills do not look like the old landfills that are on the current Superfund list. Today's operating landfills do not continue to take hazardous waste. In addition, they do not receive bulk liquids. They have gas control systems, liners, leachate collection systems, and extensive groundwater monitoring systems. Perhaps most importantly, they are better sited and located in the first place to take advantage of natural geological conditions.
Landfills can also turn into a resource. Methane gas recovery is occurring at many landfills today, and CO2 recovery is being considered. After closure, landfills can be used for recreation areas such as parks, golf courses, or ski areas. Some agencies and entrepreneurs are looking at landfills as repositories of resources for the future; in other words, today's landfills might be able to be mined at some time in the future when economic conditions warrant. This situation could be particularly true of monofills, which focus on one kind of waste material like combustion ash or shredded tires.2
The implementation of IWM for residential solid waste, as illustrated in Figure 3.2, typically involves the use of a several technologies and all of the
management options already discussed. At present, most communities use two or more of the municipal solid waste (MSW) management options to dispose of their waste, but there are only a few instances where a truly integrated and optimized waste management plan has been developed. To achieve an integrated strategy for handling municipal waste, an optimization analysis combining all of the available options should be conducted. However, at present, there is no proven methodology for performing such an optimization analysis.2
SOURCES, CHARACTERISTICS, AND QUANTITIES OF SOLID WASTE
In developing solid waste management programs, it is important to identify the sources, characteristics, and quantities of solid waste. Information on these subjects, as discussed in this section, is of fundamental importance in determining the types of collection service, the types of collection vehicles to be used, the type of processing facilities, and the disposal method to be used. Construction and demolition debris and special wastes that must be collected and processed separately are also considered.
Sources of solid wastes in a community are, in general, related to land use and zoning. Although any number of source classifications can be developed, the following categories have been found useful: (1) residential, (2) commercial, (3) institutional, (4) construction and demolition, (5) municipal services, (6) treatment plant sites, (7) industrial, and (8) agricultural. Typical waste generation facilities, activities, or locations associated with each of these sources are reported in Table 3.1. As noted in Table 3.1, municipal solid waste is normally assumed to include all community wastes with the exception of wastes generated from municipal services, water and wastewater treatment plants, industrial processes, and agricultural operations. It is important to be aware that the definitions of solid waste terms and the classifications of solid waste vary greatly in the literature and in the profession. Consequently, the use of published data requires considerable care, judgment, and common sense.2
Characteristics of Solid Waste
Important characteristics of solid waste include the composition, quantities, and specific weight.
Composition Typical data on the percentage distribution for the wastes from the sources identified in Table 3.1 are reported in Table 3.2. As shown in Table 3.2, residential and commercial waste make up about 60 percent of the total municipal waste generated per person in the United States, excluding industrial and agricultural wastes. It is important to recognize that most surveys of solid
Typical Facilities, Activities, or
Types of Solid Wastes
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