13 Sources, Types, and Composition of Municipal Solid Wastes Solid wastes include all solid or semisolid materials that the possessor no longer considers of sufficient value to retain. The management of these waste materials is the fundamental concern of all the activities encompassed in solid waste management-whether the planning level is local, regional or subregional, or state and federal. For this reason, it is important to know as much about municipa solid waste (MS W) as possible. The purpose of this chapter is to identify the sources, types, and composition of solid wastes 13-1 Sources of solid wastes Knowledge of the sources and types of solid wastes, along with data on the composition and rates of generation, is basic to the design and operation of the functional elements associated with the management of solid wastes. To avoid confusion, the term refuse, often used interchangeably with the term solid wastes. is not used in this text 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 are useful: (1) residential. 2)commercial. (3) institutional (4) construction and demolition.(5)municipal services. (6)treatment lant sites. 7) industrial and (8 13.2 Types of Solid Wastes As a basis for subsequent discussions, it will be helpful to define the various types of solid wastes that are generated. It is important to be aware that the definitions of solid waste terms and the classifications vary greatly in the literature and in the profession. Consequently, the use of published data requires considerable care, judgment, and common sense. The following definitions are intended to serve as a guide and are not meant to be precise in a scientific sense Residential and commercial Residential and commercial solid wastes, excluding special and hazardous wastes discussed below consist of the organic(combustible) and inorganic (noncombustible) solid wastes from residential areas and commercial establishments. Typically, the organic fraction of residential and commercial solid waste consists of materials such as food waste (also called garbage), paper of all types corrugated cardboard (also known as paperboard and corrugated paper), plastics of all types, textiles, ubber, leather, wood, and yard wastes. The inorganic fraction consists of items such as glass, crocker tin cans, aluminum, ferrous metals, and dirt. If the waste components are not separated when discarded. then the mixture of these wastes is also known as commingled residential and commercial MSW Wastes that will decompose rapidly, especially in warm weather, are also known as putrescible waste The principal source of putrescible wastes is the handling, preparation, cooking, and eating of foods Often, decomposition will lead to the development of offensive odors and the breeding of flies. In many locations, the putrescible nature of these wastes will influence the design and operation of the solid waste collection system Although there are more than 50 classifications for paper, the waste paper found in msw is typically composed of newspaper, books and zines, commercial printing, office paper, other paperboard, paper packaging, other nonpackaging paper, tissue paper and towels, and corrugated cardboard The plastic materials found in MSw fall into the following seven categories: Polyethylene terephthalate(PeTE/l High-density polyethylene(HDPE/2) Polyvinyl chloride(Pvc/3) Low-density polyethylene (LDPE/4) Polypropylene(PP/5 Polystyrene(PS/6 Other multilayered plastic materials(7) PETE HDPE LDPE PS OTHER Fig13-1. Code designation used for vavious types of plastics 13-1
13-1 13 Sources, Types, and Composition of Municipal Solid Wastes Solid wastes include all solid or semisolid materials that the possessor no longer considers of sufficient value to retain. The management of these waste materials is the fundamental concern of all the activities encompassed in solid waste management—whether the planning level is local, regional or subregional, or state and federal. For this reason, it is important to know as much about municipal solid waste (MSW) as possible. The purpose of this chapter is to identify the sources, types, and composition of solid wastes. 13-1 Sources of Solid Wastes Knowledge of the sources and types of solid wastes, along with data on the composition and rates of generation, is basic to the design and operation of the functional elements associated with the management of solid wastes. To avoid confusion, the term refuse, often used interchangeably with the term solid wastes, is not used in this text. 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 are useful: (1) residential, (2) commercial, (3) institutional, (4) construction and demolition, (5) municipal services, (6) treatment plant sites, (7) industrial, and (8) agricultural. 13-2 Types of Solid Wastes As a basis for subsequent discussions, it will be helpful to define the various types of solid wastes that are generated. It is important to be aware that the definitions of solid waste terms and the classifications vary greatly in the literature and in the profession. Consequently, the use of published data requires considerable care, judgment, and common sense. The following definitions are intended to serve as a guide and are not meant to be precise in a scientific sense. Residential and Commercial Residential and commercial solid wastes, excluding special and hazardous wastes discussed below, consist of the organic (combustible) and inorganic (noncombustible) solid wastes from residential areas and commercial establishments. Typically, the organic fraction of residential and commercial solid waste consists of materials such as food waste (also called garbage), paper of all types, corrugated cardboard (also known as paperboard and corrugated paper), plastics of all types, textiles, rubber, leather, wood, and yard wastes. The inorganic fraction consists of items such as glass, crockery, tin cans, aluminum, ferrous metals, and dirt. If the waste components are not separated when discarded, then the mixture of these wastes is also known as commingled residential and commercial MSW. Wastes that will decompose rapidly, especially in warm weather, are also known as putrescible waste. The principal source of putrescible wastes is the handling, preparation, cooking, and eating of foods. Often, decomposition will lead to the development of offensive odors and the breeding of flies. In many locations, the putrescible nature of these wastes will influence the design and operation of the solid waste collection system . Although there are more than 50 classifications for paper, the waste paper found in MSW is typically composed of newspaper, books and magazines, commercial printing, office paper, other paperboard, paper packaging, other nonpackaging paper, tissue paper and towels, and corrugated cardboard. The plastic materials found in MSW fall into the following seven categories: • Polyethylene terephthalate (PETE/I) • High-density polyethylene (HDPE/2) • Polyvinyl chloride (PVC/3) • Low-density polyethylene (LDPE/4) • Polypropylene (PP/5) • Polystyrene (PS/6) • Other multilayered plastic materials (7) Fig13-1. Code designation used for vavious types of plastics
ot t he container (see taints a nmis ed plastic is the term used for the mixture of the ndto ide l types of plastic found in mS w Special Wastes. Special wastes from residential and commercial sources include bulky items. consumer electronics, white goods, vard wastes that are collected separately. batteries, ol, and tre nd industrial items such as furniture. lamps, bookcases, filing cabinets, and other similar items. Consumer electronics includes worn-out, broken, and other no-longerwanted items such as radios, stereos, and television sets. white goods are large worn-out or broken household, commercial, and industrial appliances such as stoves dryers. Collected separately, white goods are usually dismantled for the recovery of specific materials(e. g, copper, aluminum, etc. The principal sources of batteries are from households and automobile and other vehicle servicing facilities. Household batteries come in a variety of tvpes, including alkaline, mercurv. silver zinc. nickel and cadmium. The metals found in household batteries can cause groundwater contamination by their presence in leachate, they can also contaminate air emissions and ash from waste combustion facilities. Many states now prohibit the landfilling of household batteries. Automobiles use lead-acid each of which contains approximately 18 pounds of lead and a gallon of sulfuric acid, both hazardous materials the: principal source of used oil is from the servicing of automobiles and other moving vehicles by owners. Waste oil, not collected for recycling, is often poured onto the ground, down sanitary, combined, and storm water sewers, or into trash containers. Waste oil discharged onto the ground or into municipal sewers often contaminates surface water and groundwater as well as the soil. Waste oil placed in the same container as other solid waste components tends to contaminate the waste components and thus reduces their value as recycled materials Somewhere between 230 and 240 million rubber tires are disposed of annually in landfills or in tire stockpiles. Because tires do not compact well, their disposal in landfills is expensive and wasteful of space. Stockpiling of tires also poses serious aesthetic as well as environmental problems. Large difficult-to-extinguish fires have occurred in a number of stockpiles. In addition, stockpiled tires form an ideal breeding place for mosquitos Hazardous Wastes. Wastes or combinations of wastes that pose a substantial present hazard to human health or living organisms have been defined as hazardous wastes. the U.S. epa has defined RCRa hazardous wastes in three general categories: (1)listed wastes, (2)characteristic hazardous wastes, and (3)other hazardous wastes Institutional Institutional sources of solid waste include government centers, schools, prisons, and hospitals Excluding manufacturing wastes from prisons and medical wastes from hospitals, the solid wastes generated at these facilities are quite similar commingled Msw. In most hospitals medical wastes are handled and process separately from other solid wastes Construction and demolition Wastes from the construction, remodeling, and repairing of individual residences, commercial buildings, and other structures are classified as construction wastes. The quantities produced are difficult to estimate. The composition is variable but may include dirt: stones; concrete: bricks; plaster: streets, sidewalks, bridges, and other structures are classified as demolition wastes. The composition of demolition wastes is similar to construction wastes, but may include broken glass, plastics, and einforcing steel. Municipal Services Other community wastes, resulting from the operation and maintenance of municipal facilities and the provision of other municipal services, include street sweepings, road side litter. wastes from municipal litter containers, landscape and tree trimmings, catch-basin debris. dead animals, and abandoned vehicles. Because it is impossible to predict where dead animals and abandoned automobiles will be found, these wastes are often identified as originating from nonspecific diffuse sources. Wastes from nonspecific diffuse sources can be contrasted to that of the residential sources, which are also diffuse but specific in that the generation of the wastes is a recurring event Treatment Plant Wastes and other residues The solid and semisolid wastes from water. wastewater. and industrial waste treatment facilities termed treatment plant wastes. The specific characteristics of these materials vary, depending on
13-2 The type of plastic container can be identified by number code (1 through 7) molded into the bottom of the container (see Fig. 13-1). Mixed plastic is the term used for the mixture of the individual types of plastic found in MSW. Special Wastes. Special wastes from residential and commercial sources include bulky items, consumer electronics, white goods, yard wastes that are collected separately, batteries, oil, and tires. These wastes are usually handled separately from other residential and commercial wastes. Bulky items are large worn-out or broken household, commercial, and industrial items such as furniture, lamps, bookcases, filing cabinets, and other similar items. Consumer electronics includes worn-out, broken, and other no-longerwanted items such as radios, stereos, and television sets. White goods are large worn-out or broken household, commercial, and industrial appliances such as stoves, refrigerators, dishwashers, and clothes washers and dryers. Collected separately, white goods are usually dismantled for the recovery of specific materials (e.g., copper, aluminum, etc.). The principal sources of batteries are from households and automobile and other vehicle servicing facilities. Household batteries come in a variety of types, including alkaline, mercury, silver, zinc, nickel, and cadmium. The metals found in household batteries can cause groundwater contamination by their presence in leachate; they can also contaminate air emissions and ash from waste combustion facilities. Many states now prohibit the landfilling of household batteries. Automobiles use lead-acid batteries, each of which contains approximately 18 pounds of lead and a gallon of sulfuric acid, both hazardous materials. The principal source of used oil is from the servicing of automobiles and other moving vehicles by their owners. Waste oil, not collected for recycling, is often poured onto the ground; down sanitary, combined, and storm water sewers; or into trash containers. Waste oil discharged onto the ground or into municipal sewers often contaminates surface water and groundwater as well as the soil. Waste oil placed in the same container as other solid waste components tends to contaminate the waste components and thus reduces their value as recycled materials. Somewhere between 230 and 240 million rubber tires are disposed of annually in landfills or in tire stockpiles. Because tires do not compact well, their disposal in landfills is expensive and wasteful of space. Stockpiling of tires also poses serious aesthetic as well as environmental problems. Large, difficult-to-extinguish fires have occurred in a number of stockpiles. In addition, stockpiled tires form an ideal breeding place for mosquitos. Hazardous Wastes. Wastes or combinations of wastes that pose a substantial present or potential hazard to human health or living organisms have been defined as hazardous wastes. The U.S. EPA has defined RCRA hazardous wastes in three general categories: (1) listed wastes, (2) characteristic hazardous wastes, and (3) other hazardous wastes. Institutional Institutional sources of solid waste include government centers, schools, prisons, and hospitals. Excluding manufacturing wastes from prisons and medical wastes from hospitals, the solid wastes generated at these facilities are quite similar commingled MSW. In most hospitals medical wastes are handled and process separately from other solid wastes. Construction and Demolition Wastes from the construction, remodeling, and repairing of individual residences, commercial buildings, and other structures are classified as construction wastes. The quantities produced are difficult to estimate. The composition is variable but may include dirt; stones; concrete; bricks; plaster; lumber; shingles; and plumbing, heating, and electrical parts. Wastes from razed buildings, broken-out streets, sidewalks, bridges, and other structures are classified as demolition wastes. The composition of demolition wastes is similar to construction wastes, but may include broken glass, plastics, and reinforcing steel. Municipal Services Other community wastes, resulting from the operation and maintenance of municipal facilities and the provision of other municipal services, include street sweepings, road side litter, wastes from municipal litter containers, landscape and tree trimmings, catch-basin debris, dead animals, and abandoned vehicles. Because it is impossible to predict where dead animals and abandoned automobiles will be found, these wastes are often identified as originating from nonspecific diffuse sources. Wastes from nonspecific diffuse sources can be contrasted to that of the residential sources, which are also diffuse but specific in that the generation of the wastes is a recurring event. Treatment Plant Wastes and Other Residues The solid and semisolid wastes from water, wastewater, and industrial waste treatment facilities are termed treatment plant wastes. The specific characteristics of these materials vary, depending on the
nature of the treatment process. At present their collection is not the charge of most municipal agencies responsible for solid waste management. However, wastewater treatment plant sludges are commonly co-disposed with MSw in municipal landfills. In the future, the disposal of treatment plant sludges will likely become a major factor in any solid waste management plan Materials remaining from the combustion of wood coal, coke, and other combustible wastes are categorized as ashes and residues.( Residues from power plants normally are not included in this category because they are handled am processed separately. These residues are normally composed of fine, powder materials, cinders, clinkers, and small amounts of burned and partially burned materials Glass, crockery, and various metals are also found in the residues from municipal incinerators Industrial Solid waste excluding Sources and types of solid waste generated at industrial sites, grouped according to their Standard Industrial Classification(SIC), are reported in Table 13-1. This list excludes industrial process wastes 最量 邕 8 -月 邕 &8部a品 手8 当 o居g 冒量 多 雪238 学 8苏 13-3
13-3 nature of the treatment process. At present their collection is not the charge of most municipal agencies responsible for solid waste management. However, wastewater treatment plant sludges are commonly co-disposed with MSW in municipal landfills. In the future, the disposal of treatment plant sludges will likely become a major factor in any solid waste management plan. Materials remaining from the combustion of wood, coal, coke, and other combustible wastes are categorized as ashes and residues. (Residues from power plants normally are not included in this category because they are handled am processed separately.) These residues are normally composed of fine, powder materials, cinders, clinkers, and small amounts of burned and partially burned materials. Glass, crockery, and various metals are also found in the residues from municipal incinerators. Industrial Solid Waste Excluding Process Wastes Sources and types of solid waste generated at industrial sites, grouped according to their Standard Industrial Classification (SIC), are reported in Table 13-1 . This list excludes industrial process wastes and any hazardous wastes that may be generated. Tab 13-1 Sources and types of industrial wastes
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Agricultural wastes Wastes and residues resulting from diverse agricultural activities-such as the planting and harvesting of row, field, tree and vine crops, the production of milk; the production of animals for slaughter; and the operation of feedlots-are collectively called agricultural wastes. At present, the disposal of these wastes is not the responsibility of most municipal and county solid waste management agencies However. in many areas the disposal of animal manure has become a critical problem. especially from feedlots and dairies 13.3 Composition of Solid Wastes Composition is the term used to describe the individual components that make up a solid waste stream and their relative distribution usually based on percent by weight. Information on the composition of t in evaluati plans. For example, if the solid wastes generated at a commercial facility consist of only paper products, the use of special processing equipment, such as shredders and balers, may be appropriate Separate collection may also be considered if the city or collection agency is involved in a paper-products recycling program. The potential for significant changes in composition in the future is considered at the end of this chapter Composition of Msw The total solid wastes from a community are composed of the waste materials identified in Table 13-1 Typical data on the distribution of MSw are presented in Table 13-2. As noted in Table 13-2, the residential and commercial portion makes up about 50 to 75 percent of the total MSw generated in a community. The actual percentage distribution will depend on(1)the extent of the construction and demolition activities, (2) the extent of the municipal services provided, and(3)the types of water and wastewater treatment processes that are used. The wide variation in the special wastes category (3 to 12 percent)is due to the fact that in many communities yard wastes are collected separately. The percentage of construction and demolition wastes varies widely depending on the part of the country and the general health of the local, state, and national economy. The percentage of treatment, plant sludges will also vary widely depending on the extent and type of water and wastewater treatment Distribution of Individual waste Components Information and data on the physical composition of solid wastes are important in the selection and operation of equipment and facilities, in assessing the feasibility of resource and energy recovery and in the analysis and design of landfill disposal facilities). Published distribution data should be used cautiously because the effects of recycling activities and the use of kitchen food waste grinders are often not reflected in earlier data 13-5
13-5 Agricultural Wastes Wastes and residues resulting from diverse agricultural activities—such as the planting and harvesting of row, field, tree and vine crops; the production of milk; the production of animals for slaughter; and the operation of feedlots—are collectively called agricultural wastes. At present, the disposal of these wastes is not the responsibility of most municipal and county solid waste management agencies. However, in many areas the disposal of animal manure has become a critical problem, especially from feedlots and dairies. 13.3 Composition of Solid Wastes Composition is the term used to describe the individual components that make up a solid waste stream and their relative distribution, usually based on percent by weight. Information on the composition of solid wastes is important in evaluating equipment needs, systems, and management programs and plans. For example, if the solid wastes generated at a commercial facility consist of only paper products, the use of special processing equipment, such as shredders and balers, may be appropriate. Separate collection may also be considered if the city or collection agency is involved in a paper-products recycling program. The potential for significant changes in composition in the future is considered at the end of this chapter. Composition of MSW The total solid wastes from a community are composed of the waste materials identified in Table 13-1. Typical data on the distribution of MSW are presented in Table 13-2. As noted in Table 13-2, the residential and commercial portion makes up about 50 to 75 percent of the total MSW generated in a community. The actual percentage distribution will depend on (1) the extent of the construction and demolition activities, (2) the extent of the municipal services provided, and (3) the types of water and wastewater treatment processes that are used. The wide variation in the special wastes category (3 to 12 percent) is due to the fact that in many communities yard wastes are collected separately. The percentage of construction and demolition wastes varies widely depending on the part of the country and the general health of the local, state, and national economy. The percentage of treatment, plant sludges will also vary widely depending on the extent and type of water and wastewater treatment provided. Distribution of Individual Waste Components Information and data on the physical composition of solid wastes are important in the selection and operation of equipment and facilities , in assessing the feasibility of resource and energy recovery , and in the analysis and design of landfill disposal facilities). Published distribution data should be used cautiously because the effects of recycling activities and the use of kitchen food waste grinders are often not reflected in earlier data