Nicholas P. Cheremisinoff. Handbook of Solid Waste Management and Waste Minimization Technologies

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materials use. Opportunities for source reduction are often not realized because

of existing regulations, and the industrial resources required for compliance,

focus on treatment and disposal. Source reduction is fundamentally different and

more desirable than waste management or pollution control. Pollution prevention

also includes other practices that increase efficiency in the use of energy, water,

or other natural resources and protect our resource base through conservation.

Practices include recycling, source reduction, and sustainable agriculture.

SAFE DRINKING WATER ACT

The Safe Drinking Water Act (42 U.S.C. s/s 30Of et seq. (1974)) was established

to protect the quality of drinking water in the United States. This law focuses on

all waters actually or potentially designed for drinking use, whether from

aboveground or underground sources. The act authorized EPA to establish safe

standards of purity and required all owners or operators of public water systems

to comply with primary (health-related) standards. State governments, which

assume this power from EPA, also encourage attainment of secondary standards

(nuisance-related).

TOXIC SUBSTANCES CONTROL ACT

The Toxic Substances Control Act (TSCA, 15 U.S.C. s/s 2601 et seq. (1976)) of

1976 was enacted by Congress to give EPA the ability to track the 75,000

industrial chemicals currently produced or imported into the United States. EPA

repeatedly screens these chemicals and can require reporting or testing of those

that may pose an environmental or human-health hazard. EPA can ban the

manufacture and import of those chemicals that pose an unreasonable risk. Also,

EPA has mechanisms in place to track the thousands of new chemicals that

industry develops each year with either unknown or dangerous characteristics.

EPA then can control these chemicals as necessary to protect human health and

the environment. TSCA supplements other federal statutes, including the Clean

Air Act and the Toxic Release Inventory under EPCRA.

A SHORT REVIEW

When dealing with solid wastes and pollution, there is no one single law that

applies. Environmental compliance requires a keen understanding of all the

environmental laws that may impact on an operation. The way companies address

this most effectively is through the application of an initial environmental review

or IER.

An IER examines the environmental aspects associated with an operation and

determines which regulations require compliance. Compliance is best handled by

means of an environmental management system or EMS, of which the most well-

known one is ISO 14001.

Chapter 3

MUNICIPAL SOLID

WASTE

INTRODUCTION

The disposal of municipal solid waste (MSW) is one of the more serious and

controversial urban issues facing local governments in the United States, and

indeed most technologically developed nations. Despite innovative technologies,

production decisions and marketing strategies that have helped in better managing

solid waste, per capita generation of garbage continues to surge. Local

governments dispose of solid waste through three main strategies: composting,

incineration and landfilling. Composting, a process involving bacteria as an agent

to decompose waste materials into soil additives, removes leaves and yard waste

from the waste stream, thereby lessening volume. Incineration involves the

burning of solid waste and not only effects significant volume reduction but also

produces energy in the form of steam or electricity. Because other disposal

alternatives leave some portion of the waste untreated or produce some type of

residue, landfills serve as the terminal approach to waste management.

Although using the same methodologies, solid waste management practices still

differ widely throughout the world. As examples, Japan burns more than 70% of

its solid waste, while more than 84% of American waste goes into landfills.

Unfortunately, both methods contribute to increased pollution. With its heavy

reliance on incineration, Japan must deal with dangerous air emissions and ash

disposal. Incinerator smoke contains such toxic substances as dioxins, sulfur

dioxide, and oxides of nitrogen. The concentration of dioxins in Japan's

atmosphere is three times that of the United States.

But landfills are also environmentally challenging. They contain significant

contaminants that can pollute underground aquifers and surface water. Further,

they harbor large amounts of carbon dioxide, methane, and other toxic gases that

contribute to the greenhouse effect. Eventually, landfills reach capacity and many

are being capped at great expense.

Although technology exists to remove toxic chemicals from incinerator smoke,

and to prevent landfills from leaking, it is generally expensive and subject to

strict federal and state regulation. U.S. laws authorize local governments to

participate in preparing and implementing local plans that embody sound

principles of solid waste management, natural resource conservation, and energy

production. When LCC tools are applied, more cost-effective management

practices that serve communities for many decades can be chosen. These

investments must be supplemented and focus heavily on reducing waste at the

source and recycling. Reducing garbage output is becoming a major

environmental priority in the United States. Many local governments now require

recycling and waste reduction by residents and businesses as the cornerstone of

an effective solid waste program. In this chapter we examine the problem of

MSW along with the alternative strategies and technologies that are displacing

landfilling and incineration.

THE COMPOSITION OF MUNICIPAL WASTE

Municipal solid waste (MSW) is commonly known as trash or garbage. It

comprises everyday items, such as product packaging, grass clippings, furniture,

clothing, bottles, food scraps, newspapers, appliances, paint, batteries, and other

consumer-related product forms. The composition of MSW depends on a number

of factors such as the lifestyles of the population, their relative standards of

living, general consumer patterns, and the level of technological advancement of

a particular country. In the United States the average composition (before

recycling) is widely reported to be as shown in Table 1:

A portion of household wastes are hazardous. Households often discard common

items such as paint, solvent-based cleaners, oils, batteries, and pesticides. These

items contain hazardous chemicals. Such discarded items are referred to as

household hazardous waste (HHW).

Municipal waste management systems that rely exclusively on landfills have little

need to characterize the types and quantities of material disposed, unless the

waste streams comprise significant quantities of hazardous wastes. As

communities rely more on source reduction, recycling, composting, and waste-

Table 1. Typical Composition of MSW Reported in the United States.

Waste component

Paper

Yard waste

Food waste

Plastics

Metals

Rubber, leather, textiles

Glass

Wood

Miscellaneous inorganic waste

Weight %

38.1

12.1

10.9

10.5

7.8

6.6

5.5

5.3

3.2

to-energy (WTE) technologies, the need for reliable data about what is in the

waste stream becomes paramount to the waste management program's success.

Each of these technologies addresses discrete segments of the waste stream.

These data assist municipalities in:

• Determining the best management methods for different materials

• Planning recycling and composting programs by identifying the amounts

of recyclables and organic materials generated by residential,

commercial, and possibly industrial sectors

• Sizing of WTE facilities based on the amount of wastes remaining in the

waste stream after recycling and composting

• Estimating waste transportation and separation costs using local

estimates of total municipal waste volume and weight

Waste characterization studies provide baseline data for municipalities to measure

their progress toward specific waste management goals. In addition, projections

of the size and composition of the future MSW stream helps communities plan

MSW management facilities that often have operating lifetimes of several

decades.

The use of literature reported data for local planning is likely to lead to

inaccurate estimates of local MSW quantities and composition and could result in

costly mistakes in purchasing equipment and sizing facilities. Local waste

characterizations, on the other hand, are based on actual waste stream studies

conducted at landfills, WTE facilities, materials recovery facilities (MRFs), or

transfer stations. Properly conducted studies can provide information about the

amount of specific products and materials generated by each sector (i.e.,

residential, commercial, or industrial), the amount of waste recycled, seasonal

variations in the waste stream, and differences between urban, suburban, and

rural areas. Waste characterization studies often include the following elements:

• An approach to sample collection that ensures representative sampling

• Four-season sorts of at least one week each

• Multiple waste categories (e.g., about 25), with added detail on

recyclables

• Waste quantities by generation source

• An estimation of the heat value of waste if WTE is being considered

• A survey of businesses, haulers, and brokers to quantify commercial

recycling activities and disposal practices

A waste characterization can also include sample sorts of restaurant, hotel,

office, and manufacturer waste to determine waste generation and

characterization by sector, and curbside sorts to establish baseline data for

tracking source reduction programs, household hazardous wastes, and program

effectiveness.

Identifying generation rates and management methods for commercial waste is

particularly important. On average, commercial waste accounts for 40% of the

municipal waste stream in North America, but percentages vary by community.

As an example, there are some rural areas that generate almost no commercial

waste. Construction and demolition debris is sometimes a major portion of the

waste stream and a good source of recyclable materials. Construction and

demolition debris can be included in commercial waste estimates or broken out

separately. The composition of commercial and industrial waste is significantly

different from that of residential waste. Residential waste includes high volumes

of paper, glass, food, and yard waste, whereas commercial and industrial waste

includes high volumes of paper, metals, and wood. The primary waste generators

in the commercial sector tend to be hotels, restaurants, shopping centers, and

hospitals.

Waste characterization studies need to be updated periodically to account for

changes in population density, industrial concentration, and community affluence.

To anticipate changes in the size and composition of the MSW stream and to

make decisions concerning its management, local officials generally make

projections of the future MSW stream based on the impact of at least two factors:

(a) demographics; and (b) recycling, composting, and source reduction programs.

Although consumer behavior and product composition also are important factors

affecting MSW generation and composition, the impact of these factors is

difficult to predict and can have an ambiguous overall affect. Some general

trends are, however, evident. The percentage of paper and plastics in the waste

stream is expected to continue increasing. Also, glass and steel containers are

likely to continue to be replaced by lighter materials, such as aluminum and

plastic. Changes in local industry and commerce will also affect the size and

composition of the commercial and industrial waste streams.

WASTE VOLUME GROWTH TRENDS

The volumes generated per capita also depend on similar if not the same factors

that influence composition. In the United States the combined MSW from

residents, businesses, and institutions exceeded 230 million tons (1999 data

reported by the EPA Web site: www.epa.gov). This figure represents about 4.6

lbs (2.09 kg) of waste per person per day. In contrast, in 1960, the U.S.

estimated MSW generation figure per capita was 2.7 lbs (1.22 kg). Trends in

MSW generation for the United States are shown in Fig. 1.

Figure 1. Trends in municipal waste generation growth in the United

States.

Total Waste Generation (mil tons)

250 mil tons

200 mil tons

150 mil tons

100 mil tons

50 mil tons

Per Capita Generation (lbs/person/day)

The trends shown in Fig. 1 indicate an alarming rate of increase in less than a

generation. This raises concerns for the overconsumption of nonrenewable

resources, and the ability to effectively manage these waste volumes.

Changes in MSW generation can be attributed to demographics and can be

broken down into two basic factors:

• Changes in population

• Changes in per-capita generation

Population growth or decline due to changes in the birth rate, death rate, or

migration significantly affect the generation of residential, commercial, and

industrial MSW. Although national average populations in technologically

advanced countries are expected to continue to increase, regions and localities

can expect to see much more dynamic changes due to migration and other

factors. Note also that industrial solid waste patterns are also dynamic and change

as demographic shifts in society take place. This also leads to the need for more

complex and well-thought-out waste management strategies.

Per-capita generation depends on at least three major factors: socioeconomic

status,

the degree, of urbanization, and household size. The effect of

socioeconomic status on MSW generation is uncertain. As societies become more

affluent on average, they have purchased more of all goods, which has increased

waste generation. Rural areas often have lower per-capita generation rates than

urban areas for at least some components of the waste stream (e.g., fewer

newspapers because they are printed weekly rather than daily and are more often

burned as fuel).

In the chapters to follow we will examine alternative strategies for waste

management at both the municipal and industrial levels. Bear in mind that

consumer patterns also need to change as resources become more scarce.

Recycling, composting, and source reduction initiatives have altered the MSW

stream that is sent to WTE facilities and landfills. Since these programs reduce

the portion of certain materials in the waste stream, the proportion of the

remaining, untargeted components must necessarily increase.

WASTE TO ENERGY

Incineration is the combustion of waste in a controlled manner in order to destroy

it or transform it into less hazardous, less bulky, or more controllable

constituents. Incineration may be used to dispose of a wide range of waste

streams including MSW, commercial, clinical, and certain types of industrial

waste. Incineration is generally the second most frequently selected method of

waste management after landfill for MSW.

MSW comprises residential and commercial refuse and makes up the largest

source of waste in industrialized countries. Disposal is a major concern in many

parts of the world simply because landfill space is becoming scarce. Although

there are significant environmental trade-offs, incineration of MSW with energy

recovery can be viewed as an attractive alternative to landfilling in many

situations.

The construction of energy from waste facilities is very controversial and has

evoked a great deal of public criticism and objections, largely because of air

pollution. Since there is a greater prevalence for toxic and hazardous materials in

industrial waste streams, the successful application to managing industry solid

waste problems has been at a lower level, but still substantial.

There are three basic methods relied upon to convert solid waste into useful

energy such as electricity and heat. In the case of MSW, all three methods

produce energy from the organic portion of the waste. The organic matter would

eventually be converted to methane and carbon dioxide by natural processes.

Methane is the main constituent of natural gas, and hence these technology

options simply capitalize on what would happen naturally. Since methane

formation from the decomposition of the organic waste components of MSW

occurs naturally, energy from waste can be viewed in part as not contributing to

greenhouse gases. Determining the specific technology that is most appropriate

for a given region depends on a number of factors, including the local methods of

collecting, processing, and disposing of MSW, and local environmental

regulations.

LIFE-CYCLE CONSIDERATIONS

The benefits associated with incineration technologies include:

• A reduction in the volume and weight of waste, especially of bulky

solids with a high combustible content. The reduction can be up to 90%

of the volume and 75% of the weight of materials that would otherwise

go to landfill.

• Destruction of some wastes and detoxification of others to render them

more suitable for final disposal, e.g. combustible carcinogens,

pathologically contaminated materials, toxic organic compounds, or

biologically active materials that could affect sewage treatment works.

• Destruction of the organic component of biodegradable waste that, when

landfilled, directly generates landfill gas (LFG).

• Recovery of energy from organic wastes with sufficient organic value.

• Replacement of fossil fuel for energy generation with beneficial

consequences in the greenhouse effect.

The disadvantages of incineration technologies largely lie with environmental

trade-offs from transforming solid waste to air pollution. There is genuine

concern over the environmental and public health implications of incineration,

particularly due to heavy metals and dioxins in incinerator emissions to the

atmosphere. This concern led to the adoption of legislation controlling the

incineration process in most industrialized countries. The ongoing costs for

controls increase the life cycle costs significantly. Although modern incinerators

comply with existing air emissions legislation, there is still public concern that

the levels emitted pose long-term health risks. The emissions of most

environmental concern from mass burn incinerators for MSW are:

• Particulate matter

• Heavy metals such as mercury, cadmium, lead, arsenic, zinc,

chromium, copper, nickel, etc.

• Acidic and corrosive gases such as hydrogen chloride, hydrogen

fluoride, sulfur dioxide, and nitrogen oxides

• Products of incomplete combustion such as carbon monoxide, dioxins,

furans, and polycyclic aromatic hydrocarbons

• Contaminated wastewater

• Contaminated ash

Strong advocates of this technology argue that air emission standards are strict

and that these technologies are inherently safe. However, we must always bear in

mind that there are still many unknowns about the long-term health risks of

numerous air emissions.

Other issues and concerns regarding the use of incineration as a waste treatment

method are as follows:

• Because of the high capital investment requirements, incineration

generally entails much higher costs and longer payback periods than

final disposal to landfill.

• There is a lack of flexibility in the choice of waste disposal options once

incineration is chosen. Because of the high capital cost, the incinerator

must be tied to long-term waste disposal contracts.

• The incinerator is designed on the basis of a certain calorific value for

the waste. Removal of materials such as paper and plastics for recycling

and resource recovery reduce the overall calorific value of the waste and

consequently affect incinerator performance.

• The incineration process still produces a solid waste residue that requires

management and final disposal.