Read this chapter. From your readings thus far, can you link any changes in environmental management with major events which have shaped our attitudes towards the environment?
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The chapter, The Evolution of Environmental Policy in the United States, presents and discusses how our current environmental policy evolved. Although the National Environmental Policy Act (NEPA) provided lofty goals for environmental policy, and a legal basis for action, human actions produce large quantities of waste which are harmful to people and our ecosystem health if not managed properly.
This chapter is about how we manage these wastes (Systems of Waste Management), the laws and regulations that define our system of waste management (Government and Laws on the Environment), and how we determine the consequences, i.e. risks, associated with chemicals released into the environment (Risk Assessment Methodology for Conventional and Alternative Sustainability Options). Of course, environmental policies continue to evolve, and although we may not know the exact pathway or form they will take, future environmental policy will most certainly build upon the laws and regulations we use to manage human interaction with the environment. Consequently, it is important to understand our current system, its legal and philosophical underpinnings, and the quantitative basis for setting risk-based priorities.
In April 2007, the case Massachusetts vs. the Environmental Protection Agency exemplified how we have adapted our system of environmental management to meet modern global challenges. The U.S. Supreme Court ruled the U.S. Environmental Protection Agency (EPA) had misinterpreted the Clean Air Act by not classifying and regulating carbon dioxide as a pollutant (the plaintiffs involved 12 states and several cities).
Until that time, several administrations claimed the Act did not give the EPA legal authority to regulate carbon dioxide and other greenhouse gases. At the time the Clean Air Act was passed, "clean air" was believed to mean visibly clean air that is free of pollutants that could harm humans. Although there was concern about global climate change due to greenhouse gas emissions, the gases themselves were not considered "pollutants."
This ruling set the stage for the EPA to regulate greenhouse gases through a series of findings, hearings, rulings, and regulations, in accordance with terms set out in the Clean Air Act.
In addition to helping mitigate global climate change, this case illustrates how we can adapt the environmental management systems we have put in place to address future challenges. Laws that are forward-thinking, not overly proscriptive, and administratively flexible, may accommodate unforeseen problems and needs. Of course, this does not preclude the passage of new laws or amendments or imply we can adapt our environmental laws to future problems.
by Krishna Reddy
In this module, we cover the following topics: 1. environmental regulations governing the management of solid and hazardous wastes, radioactive waste, and medical waste, 2. environmental concerns with growing quantities and improper management of waste, and 3. integrated waste management strategies.
After reading this module, students should be able to:
Waste is an inevitable by-product of human life. Virtually every human activity generates some type of material side effect or by-product. When the materials that constitute these by-products are not useful, or have been degraded so they no longer fulfill their original or other useful purpose, they are classified as a waste material.
Practically speaking, wastes are generated from a wide range of sources and are usually classified by their respective sources. Common generative activities include those associated with residences, commercial businesses and enterprises, institutions, construction and demolition activities, municipal services, and water/wastewater and air treatment plants, and municipal incinerator facilities. Further, wastes are generated from many industrial processes, including industrial construction and demolition, fabrication, manufacturing, refineries, chemical synthesis, and nuclear power/nuclear defense sources (often generating low- to high-level radioactive wastes).
Population growth and urbanization (with increased industrial, commercial and institutional establishments) contribute to increased waste production, as do the rapid economic growth and industrialization throughout the developing world.
These social and economic changes have led to an ever-expanding consumption of raw materials, processed goods, and services. While these trends have, in many ways, improved the quality of life for millions of people, they come with drastic costs to the environment. Proper management of a range of wastes is necessary to protect public health and the environment and ensure sustained economic growth.
Many believe incineration and landfill disposal are preferred options for dealing with waste products; however, we can recycle or re-use many wastes. We can reclaim or re-generate waste materials to use them again for their original or similar purpose, or we can physically or chemically change them for alternative uses.
As natural resources continue to be depleted, and as incineration and landfill disposal options become more costly and unsustainable, government agencies have promoted many economic and social incentives to prevent or reduce waste generation and develop new methods and technologies for recycling and reusing wastes. These efforts can have broader implications for energy conservation and the reduction of greenhouse gas emissions that contribute to global climate change, and foster sustainable waste management practices.
This section provides an overview of the existing regulatory framework mandating waste management, environmental concerns associated with waste generation and management, and alternatives for the proper waste management. It also highlights recent developments in sustainable waste management systems. Although the content reflects the regulatory framework and practices in the United States, similar developments and actions have occurred in other developed countries and are increasingly being initiated in developing countries.
During the 20th century, especially following World War II, the United States experienced unprecedented economic growth. Much of the growth was fueled by rapid and increasingly complex industrialization. With advances in manufacturing and chemical applications also came increases in the volume, and in many cases the toxicity, of generated wastes.
Few if any controls or regulations were in place to handle toxic materials or waste disposal. Continued industrial activity led to several high-profile examples of detrimental consequences to the environment. Finally, several forms of intervention, in the form of government regulation and citizen action, occurred in the early 1970s.
Ultimately, state and federal governments promulgated several regulations to ensure the public health safety and the environment (Government and Laws on the Environment). With respect to waste materials, the United States Congress enacted the Resource Conservation and Recovery Act (RCRA), in 1976 and amended in 1984, a comprehensive framework to manage hazardous and non-hazardous solid wastes in the United States.
RCRA stipulates broad and general legal objectives and mandates the United States Environmental Protection Agency (EPA) to develop specific regulations to implement and enforce the law. The RCRA regulations are contained in Title 40 of the Code of Federal Regulations (CFR), Parts 239 to 299. States and local governments can adopt the federal regulations, or develop and enforce more stringent regulations than those specified in RCRA. Similar regulations were developed worldwide to manage waste in other countries.
The broad goals of RCRA include: (1) to protect public health and the environment from the hazards of waste disposal; (2) to conserve energy and natural resources; (3) to reduce or eliminate waste; and (4) to make sure that wastes are managed in an environmentally-sound manner (e.g. the remediation of waste which may have spilled, leaked, or been improperly disposed). The RCRA only focuses on active and future facilities and does not address abandoned or historical sites, which are managed under a different regulatory framework, known as the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), or more commonly known as "Superfund."
RCRA defines solid waste as any garbage or refuse, sludge from a wastewater treatment plant, water supply treatment plant, or air pollution control facility and other discarded material, including solid, liquid, semi-solid, or contained gaseous material resulting from industrial, commercial, mining, and agricultural operations, and from community activities. In general, we categorize solid waste as non-hazardous or hazardous waste.
Non-hazardous solid waste can be trash or garbage households, offices, and other sources generate. Generally, these materials are classified as municipal solid waste (MSW). Alternatively, non-hazardous materials, that result from the production of goods and products by various industries (e.g. coal combustion residues, mining wastes, cement kiln dust), are collectively known as industrial solid waste.
The regulations pertaining to non-hazardous solid waste are contained in 40 CFR Parts 239 to 259 (known as RCRA Subtitle D regulations). These regulations prohibit the open dumping of solid waste, mandates the development of comprehensive plans to manage municipal solid waste (MSW) and non-hazardous industrial waste, and establishes criteria for MSW landfills and other solid waste disposal facilities. Because they are classified as non-hazardous material, many components of MSW and industrial waste have potential for recycling and re-use. Significant efforts are underway by both government agencies and industry to advance these objectives.
Hazardous waste, generated by industries and businesses (e.g. dry cleaners and auto repair shops), is constituted of materials that are dangerous or potentially harmful to human health and the environment. The regulatory framework with respect to hazardous waste, specifically hazardous waste identification, classification, generation, management, and disposal, is described in 40 CFR Parts 260 through 279 (collectively known as RCRA Subtitle C regulations). These regulations control hazardous waste from the time they are generated until their ultimate disposal (a timeline often referred to as "cradle to grave").
According to the RCRA Subtitle C regulations, solid waste is defined as hazardous if it appears in one of the four hazardous waste classifications:
Additionally, a waste is classified as hazardous if it exhibits at least one of these four characteristics:
Although non-hazardous waste (municipal solid waste and industrial non-hazardous waste) and hazardous waste are regulated by RCRA, nuclear or radioactive waste is regulated in accordance with the Atomic Energy Act of 1954 by the Nuclear Regulatory Commission (NRC) in the United States.
Radioactive wastes are characterized according to four categories: (1) High-level waste (HLW), (2) Transuranic waste (TRU), (3) Low-level waste (LLW), and (4) Mill tailings. Various radioactive wastes decay at different rates, but health and environmental dangers due to radiation may persist for hundreds or thousands of years.
High-level waste (HLW) is typically liquid or solid waste that results from government defense related activities or from nuclear power plants and spent fuel assemblies. These wastes are extremely dangerous due to their heavy concentrations of radionuclides, and humans must not come into contact with them.
Transuranic waste (TRU) mainly results from the reprocessing of spent nuclear fuels and from the fabrication of nuclear weapons for defense projects. They are characterized by moderately penetrating radiation and a decay time of approximately twenty years until safe radionuclide levels are achieved. Following the passage of a reprocessing ban in 1977, most of this waste generation ended. Even though the ban was lifted in 1981, TRU continues to be rare because reprocessing of nuclear fuel is expensive. Further, because the extracted plutonium may be used to manufacture nuclear weapons, political and social pressures minimize these activities.
Low-level wastes (LLW) include much of the remainder of radioactive waste materials. They constitute over 80 percent of the volume of all nuclear wastes, but only about two percent of total radioactivity. Sources of LLW include all of the previously cited sources of HLW and TRU, plus wastes generated by hospitals, industrial plants, universities, and commercial laboratories. LLW is much less dangerous than HLW, and NRC regulations allow some low-level wastes to be released to the environment. LLW may also be stored or buried until the isotopes decay to levels low enough such that it may be disposed of as non-hazardous waste. LLW disposal is managed at the state level, but requirements for operation and disposal are established by the EPA and NRC.
The Occupational Health and Safety Administration (OSHA) is the agency in charge of setting the standards for workers that are exposed to radioactive materials.
Mill tailings generally consist of residues from the mining and extraction of uranium from its ore. There are more than 200 million tons of radioactive mill-tailings in the United States, and all of it is stored in sparsely populated areas within the western states, such as Arizona, New Mexico, Utah, and Wyoming. These wastes emit low-level radiation, and much of it is buried to reduce dangerous emissions.
Another type of waste that is of environmental concern is medical waste. Medical waste is regulated by several federal agencies, including the USEPA, OSHA, the Center for Disease Control and Prevention (CDC) of the U.S. Department of Health and Human Services, and the Agency for Toxic Substances and Disease Registry (ATSDR) of the Public Health Service, U.S. Department of Health and Human Services. During 1987-88, medical wastes and raw garbage washed up on beaches along the New Jersey Shore of the United States on several occasions (called, "Syringe Tide") which required closure of beaches. The U.S. Congress subsequently enacted the Medical Waste Tracking Act (MWTA) to evaluate management issues and potential risks related to medical waste disposal.
The seven types of wastes listed under the Medical Waste Tracking Act include:
Low-level nuclear wastes are produced in hospitals by pharmaceutical laboratories and in performing nuclear medicine procedures (e.g. medical imaging to detect cancers and heart disease); however, the danger posed by these wastes is relatively low. A variety of hazardous substances have also been identified in medical wastes, including metals such as lead, cadmium, chromium, and mercury; and toxic organics such as dioxins and furans. All medical wastes represent a small fraction of total waste stream, estimated to constitute a maximum of approximately two percent.
Medical wastes are commonly disposed of through incineration: as with most wastes, the resulting volume is greatly reduced, and it assures the destruction and sterilization of infectious pathogens. Disadvantages include the potential of air pollution risks from dioxins and furans as well as the necessary disposal of potentially hazardous ash wastes. New options for disposal of medical wastes (including infectious wastes) are still being explored. Some other technologies include irradiation, microwaving, autoclaving, mechanical alternatives, and chemical disinfection, among others.
An enormous quantity of wastes are generated and disposed of annually. Alarmingly, this quantity continues to increase on an annual basis. Industries generate and dispose over 7.6 billion tons of industrial solid wastes each year, and it is estimated that more than 40 million tons of this waste is hazardous. Nuclear wastes and medical wastes are also increasing in quantity every year.
Generally speaking, developed nations generate more waste than developing nations due to higher rates of consumption. Not surprisingly, the United States generates more waste per capita than any other country. High waste per capita rates are also very common throughout Europe and developed nations in Asia and Oceania.
In the United States, about 243 million tons (243 trillion kg) of municipal solid waste (MSW) is generated per year, which is equal to about 4.3 pounds (1.95 kg) of waste per person per day. Nearly 34 percent of MSW is recovered and recycled or composted, approximately 12 percent is burned a combustion facilities, and the remaining 54 percent is disposed of in landfills. Waste stream percentages also vary widely by region. As an example, San Francisco, California captures and recycles nearly 75 percent of its waste material, whereas Houston, Texas recycles less than three percent.
With respect to waste mitigation options, landfilling is quickly evolving into a less desirable or feasible option. Landfill capacity in the United States has been declining primarily due to (a) older existing landfills that are increasingly reaching their authorized capacity, (b) the promulgation of stricter environmental regulations has made the permitting and siting of new landfills increasingly difficult, (c) public opposition (a sentiment described as "not In my backyard" or NIMBYism) delays or, in many cases, prevents the approval of new landfills or expansion of existing facilities. Ironically, much of this public opposition arises from misconceptions about landfilling and waste disposal practices that are derived from environmentally detrimental historic activities and practices that are no longer in existence. Regardless of the degree or extent of justification, NIMBYism is a potent opposition phenomenon, whether it is associated with landfills or other land use activities, such as airports, prisons, and wastewater treatment facilities.
Prior to the passage of environmental regulations, wastes were disposed improperly without due consideration of potential effects on the public health and the environment. This practice has led to many contaminated sites where soils and groundwater have been contaminated and pose risk to the public safety. Of more than 36,000 environmentally impacted candidate sites, there are more than 1,400 sites listed under the Superfund program National Priority List (NPL) which require immediate cleanup resulting from acute, imminent threats to environmental and human health.
The USEPA identified about 2,500 additional contaminated sites that eventually require remediation. The United States Department of Defense maintains 19,000 sites, many of which have been extensively contaminated from a variety of uses and disposal practices. Further, approximately 400,000 underground storage tanks have been confirmed or are suspected to be leaking, contaminating underlying soils and groundwater.
More than $10 billion (more than $25 billion in current dollars) were specifically allocated by CERCLA and subsequent amendments to mitigate impacted sites. However, the USEPA has estimated that the value of environmental remediation exceeds $100 billion. Alarmingly, if past expenditures on NPL sites are extrapolated across remaining and proposed NPL sites, this total may be significantly higher – well into the trillions of dollars.
It is estimated that more than 4,700 facilities in the United States currently treat, store or dispose of hazardous wastes. Of these, about 3,700 facilities that house approximately 64,000 solid waste management units (SWMUs) may require corrective action. Accidental spillage of hazardous wastes and nuclear materials due to anthropogenic operations or natural disasters has also caused enormous environmental damage as evidenced by the events such as the facility failure in Chernobyl, Ukraine (formerly USSR) in 1986, the effects of Hurricane Katrina that devastated New Orleans, Louisiana in 2005, and the 2011 Tōhoku earthquake and tsunami in Fukushima, Japan.
A wide variety of chemicals are present within waste materials, many of which pose a significant environmental concern. Though the leachate generated from the wastes may contain toxic chemicals, the concentrations and variety of toxic chemicals are quite small compared to hazardous waste sites.
For example, explosives and radioactive wastes are primarily located at Department of Energy (DOE) sites because many of these facilities have been historically used for weapons research, fabrication, testing, and training. Organic contaminants are largely found at oil refineries, or petroleum storage sites, and inorganic and pesticide contamination usually is the result of a variety of industrial activities as well as agricultural activities. Yet, soil and groundwater contamination are not the only direct adverse effects of improper waste management activities – recent studies have also shown that greenhouse gas emissions from the wastes are significant, exacerbating global climate change.
A wide range of toxic chemicals, with an equally wide distribution of respective concentrations, is found in waste streams. These compounds may be present in concentrations that alone may pose a threat to human health or may have a synergistic/cumulative effect due to the presence of other compounds. Exposure to hazardous wastes has been linked to many types of cancer, chronic illnesses, and abnormal reproductive outcomes such as birth defects, low birth weights, and spontaneous abortions. Many studies have been performed on major toxic chemicals found at hazardous waste sites incorporating epidemiological or animal tests to determine their toxic effects.
As an example, the effects of radioactive materials are classified as somatic or genetic. The somatic effects may be immediate or occur over a long period of time. Immediate effects from large radiation doses often produce nausea and vomiting, and may be followed by severe blood changes, hemorrhage, infection, and death. Delayed effects include leukemia, and many types of cancer including bone, lung, and breast cancer.
Genetic effects have been observed in which gene mutations or chromosome abnormalities result in measurable harmful effects, such as decreases in life expectancy, increased susceptibility to sickness or disease, infertility, or even death during embryonic stages of life. Because of these studies, occupational dosage limits have been recommended by the National Council on Radiation Protection.
Similar studies have been completed for a wide range of potentially hazardous materials. These studies have, in turn, been used to determine safe exposure levels for several exposure scenarios, including those that consider occupational safety and remediation standards for a variety of land use scenarios, including residential, commercial, and industrial land uses.
The chemicals found in wastes not only pose a threat to human health, but they also have profound effects on entire eco-systems. Contaminants may change the chemistry of waters and destroy aquatic life and underwater eco-systems that are depended upon by more complex species. Contaminants may also enter the food chain through plants or microbiological organisms, and higher, more evolved organisms bioaccumulate the wastes through subsequent ingestion.
As the contaminants move farther up the food chain, the continued bioaccumulation results in increased contaminant mass and concentration. In many cases, toxic concentrations are reached, resulting in increased mortality of one or more species. As the populations of these species decrease, the natural inter-species balance is affected. With decreased numbers of predators or food sources, other species may be drastically affected, leading to a chain reaction that can affect a wide range of flora and fauna within a specific eco-system. As the eco-system continues to deviate from equilibrium, disastrous consequences may occur. Examples include the near extinction of the bald eagle due to persistent ingestion of DDT-impacted fish, and the depletion of oysters, crabs, and fish in Chesapeake Bay due to excessive quantities of fertilizers, toxic chemicals, farm manure wastes, and power plant emissions.
The long-recognized hierarchy of management of wastes, in order of preference consists of prevention, minimization, recycling and reuse, biological treatment, incineration, and landfill disposal (see Figure Hierarchy of Waste Management).
The ideal waste management alternative is to prevent waste generation in the first place. Hence, waste prevention is a basic goal of all the waste management strategies. We can employ many technologies throughout the manufacturing, use, and post-use portions of product life cycles to eliminate waste and reduce or prevent pollution. Some representative strategies include environmentally-conscious manufacturing methods that incorporate less hazardous or harmful materials, modern leakage detection systems for material storage, innovative chemical neutralization techniques to reduce reactivity, and water saving technologies that reduce the need for fresh water inputs.
In many cases, we cannot eliminate wastes from our processes. However, we can implement strategies to reduce or minimize waste generation. Waste minimization, or source reduction, refers to the collective strategies to design and make products and services that minimize the amount of generated waste and reduce the toxicity of the resultant waste.
Often these efforts come from identifying trends and specific products that may cause problems in the waste stream and taking steps to halt these problems. In industry, we can reduce waste by reusing materials, using less hazardous substitute materials, and by modifying components of design and processing. We can realize many benefits from minimizing waste and reducing our use of sources, such as natural resources and waste toxicity.
Waste minimization strategies are common in manufacturing applications; saving material use preserves resources and saves significant manufacturing-related costs. Advancements in streamlined packaging reduces material use, increased distribution efficiency reduces fuel consumption and air emissions. Furthermore, we can engineer building materials with specific favorable properties that, when accounted for in the structural design, can reduce the overall mass and weight of material needed. This reduces the need for excess material and reduces waste associated with component fabrication.
The dry cleaning industry offers an excellent example of product substitution to reduce toxic waste generation. For decades, dry cleaners used tetrachloroethylene, or "perc" as a dry cleaning solvent. Although effective, tetrachloroethylene is a relatively toxic compound. Additionally, it is easily introduced into the environment, where it is highly recalcitrant due to its physical properties. Furthermore, when its degradation occurs, the intermediate daughter products generated are more toxic to human health and the environment.
Because of its toxicity and impact on the environment, the dry cleaning industry has adopted new practices and increasingly utilizes less toxic replacement products, including petroleum-based compounds. Further, new emerging technologies are incorporating carbon dioxide and other relatively harmless compounds. While these substitute products have in many cases been mandated by government regulation, they have also been adopted in response to consumer demands and other market-based forces.
Recycling refers to recovering useful materials, such as glass, paper, plastics, wood, and metals from the waste stream so we can use them to make new products. By incorporating recycled materials, we reduce the amount of raw materials needed. Recycling reduces the need to exploit natural resources for raw materials, and allows us to recover and use waste materials as valuable resource materials.
Recycling wastes conserves natural resources, reduces energy consumption, reduces emissions generated from extracting virgin materials and their subsequent manufacture into finished products, reduces energy consumption and greenhouse gas emissions that contribute to global climate change, and reduces the incineration or landfilling of the materials that have been recycled. Moreover, recycling creates several economic benefits, including the potential to create job markets and drive growth.
Common recycled materials include paper, plastics, glass, aluminum, steel, and wood. We can also reuse many construction materials, such as concrete, asphalt materials, masonry, and reinforced steel. We can recover and reuuse "green" plant-based wastes mulch and fertilizer applications. Many industries also recover various by-products and/or refine and "re-generate" solvents for reuse.
Examples include copper and nickel recovery from metal finishing processes; the recovery of oils, fats, and plasticizers by solvent extraction from filter media such as activated carbon and clays; and acid recovery by spray roasting, ion exchange, or crystallization. Furthermore, we can recover a range of used food-based oils to use in "biodiesel" applications.
We encounter many examples of successful recycling and reuse efforts every day. In some cases, the recycled materials are used as input materials and are heavily processed into end products. Common examples include the use of scrap paper for new paper manufacturing, or the processing of old aluminum cans into new aluminum products.
In other cases, reclaimed materials undergo little or no processing prior to their re-use. Some common examples include the use of tree waste as wood chips, or the use of brick and other fixtures into new structural construction. In any case, the success of recycling depends on effective collection and processing of recyclables, markets for reuse (e.g. manufacturing and/or applications that utilize recycled materials), and public acceptance and promotion of recycled products and applications utilizing recycled materials.
Landfill disposal of wastes containing significant organic fractions is increasingly discouraged in many countries, including the United States. Such disposal practices are even prohibited in several European countries. Since landfilling does not provide an attractive management option, other techniques have been identified. One option is to treat waste so that biodegradable materials are degraded and the remaining inorganic waste fraction (known as residuals) can be subsequently disposed or used for a beneficial purpose.
Biodegradation of wastes can be accomplished by using aerobic composting, anaerobicdigestion, or mechanical biological treatment (MBT) methods. If the organic fraction can be separated from inorganic material, aerobic composting or anaerobic digestion can be used to degrade the waste and convert it into usable compost. For example, organic wastes such as food waste, yard waste, and animal manure that consist of naturally degrading bacteria can be converted under controlled conditions into compost, which can then be utilized as natural fertilizer.
Aerobic composting is accomplished by placing selected proportions of organic waste into piles, rows or vessels, either in open conditions or within closed buildings fitted with gas collection and treatment systems. During the process, bulking agents such as wood chips are added to the waste material to enhance the aerobic degradation of organic materials. Finally, the material is allowed to stabilize and mature during a curing process where pathogens are concurrently destroyed. The end-products of the composting process include carbon dioxide, water, and the usable compost material.
We can use compost material in a variety of applications, such as adding it to soil for plant cultivation, and remediating soils, groundwater, and stormwater. Composting can be labor-intensive, and the quality of the compost is heavily dependent on proper control of the composting process. Inadequate control of the operating conditions can result in compost that is unsuitable for beneficial applications.
Nevertheless, composting is increasingly popular; composting diverted 82 million tons of waste material away the landfill waste stream in 2009, increased from 15 million tons in 1980. This diversion also prevented the release of approximately 178 million metric tons of carbon dioxide in 2009 – an amount equivalent to the yearly carbon dioxide emissions of 33 million automobiles.
In some cases, aerobic processes are not feasible. As an alternative, anaerobic processes may be utilized. Anaerobic digestion consists of degrading mixed or sorted organic wastes in vessels under anaerobic conditions. The anaerobic degradation process produces a combination of methane and carbon dioxide (biogas) and residuals (biosolids).
Biogas can be used for heating and electricity production, while residuals can be used as fertilizers and soil amendments. Anaerobic digestion is a preferred degradation for wet wastes as compared to the preference of composting for dry wastes. The advantage of anaerobic digestion is biogas collection; this collection and subsequent beneficial utilization makes it a preferred alternative to landfill disposal of wastes. Also, waste is degraded faster through anaerobic digestion as compared to landfill disposal.
Another waste treatment alternative, mechanical biological treatment (MBT), is not common in the United States. However, this alternative is widely used in Europe. During implementation of this method, waste material is subjected to a combination of mechanical and biological operations that reduce volume through the degradation of organic fractions in the waste. Mechanical operations such as sorting, shredding, and crushing prepare the waste for subsequent biological treatment, consisting of either aerobic composting or anaerobic digestion. Following the biological processes, the reduced waste mass may be subjected to incineration.
Waste degradation not only produces useful solid end-products (such as compost), degradation by-products can also be used as a beneficial energy source. As discussed above, anaerobic digestion of waste can generate biogas, which can be captured and incorporated into electricity generation. Alternatively, waste can be directly incinerated to produce energy. Incineration consists of waste combustion at very high temperatures to produce electrical energy. The byproduct of incineration is ash, which requires proper characterization prior to disposal, or in some cases, beneficial re-use.
While public perception of incineration can be negative, this is often based reactions to older, less efficient technologies. New incinerators are cleaner, more flexible and efficient, and are an excellent means to convert waste to energy while reducing the volume of waste. Incineration can also offset fossil fuel use and reduce greenhouse gas (GHG) emissions (Bogner et al., 2007). It is widely used in developed countries due to landfill space limitations. It is estimated that about 130 million tons of waste are annually combusted in more than 600 plants in 35 countries. Further, incineration is often used to effectively mitigate hazardous wastes such as chlorinated hydrocarbons, oils, solvents, medical wastes, and pesticides.
Despite all these advantages, incineration is often viewed negatively because of the resulting air emissions, the creation of daughter chemical compounds, and production of ash, which is commonly toxic. Currently, many 'next generation" systems are being researched and developed, and the USEPA is developing new regulations to carefully monitor incinerator air emissions under the Clean Air Act.
Despite advances in reuse and recycling, landfill disposal remains the primary waste disposal method in the United States. As previously mentioned, the rate of municipal solid waste (MSW) generation continues to increase, but overall landfill capacity is decreasing. New regulations concerning proper waste disposal and the use of innovative liner systems to minimize the potential of groundwater contamination from leachate infiltration and migration have resulted in a substantial increase in the costs of landfill disposal.
Also, public opposition to landfills continues to grow, partially inspired by memories of historic uncontrolled dumping practices the resulting undesirable side effects of uncontrolled vectors, contaminated groundwater, unmitigated odors, and subsequent diminished property values.
Landfills can be designed and permitted to accept hazardous wastes in accordance with RCRA Subtitle C regulations, or they may be designed and permitted to accept municipal solid waste in accordance with RCRA Subtitle D regulations. Regardless of their waste designation, landfills are engineered structures consisting of bottom and side liner systems, leachate collection and removal systems, final cover systems, gas collection and removal systems, and groundwater monitoring systems ( Sharma and Reddy, 2004).
An extensive permitting process is required for siting, designing and operating landfills. Post-closure monitoring of landfills is also typically required for at least 30 years. Because of their design, wastes within landfills are degraded anaerobically. During degradation, biogas is produced and collected. The collection systems prevent uncontrolled subsurface gas migration and reduce the potential for an explosive condition. The captured gas is often used in cogeneration facilities for heating or electricity generation. Further, upon closure, many landfills undergo "land recycling" and redeveloped as golf courses, recreational parks, and other beneficial uses.
Wastes commonly exist in a dry condition within landfills, and as a result, the rate of waste degradation is commonly very slow. These slow degradation rates are coupled with slow rates of degradation-induced settlement, which can in turn complicate or reduce the potential for beneficial land re-use at the surface. Recently, the concept of bioreactor landfills has emerged, which involves recirculation of leachate and/or injection of selected liquids to increase the moisture in the waste, which in turn induces rapid degradation. The increased rates of degradation increase the rate of biogas production, which increases the potential of beneficial energy production from biogas capture and utilization.
Many wastes, such as high-level radioactive wastes, will remain dangerous for thousands of years, and even municipal solid waste (MSW) can produce dangerous leachate that could devastate an entire eco-system if allowed infiltrate into and migrate within groundwater. In order to protect human health and the environment, environmental professionals must deal with problems associated with increased generation of waste materials. The solution must focus on both reducing the sources of wastes as well as the safe disposal of wastes. It is, therefore, extremely important to know the sources, classifications, chemical compositions, and physical characteristics of wastes, and to understand the strategies for managing them.
Waste management practices vary not only from country to country, but they also vary based on the type and composition of waste. Regardless of the geographical setting of the type of waste that needs to be managed, the governing principle in the development of any waste management plan is resource conservation. Natural resource and energy conservation is achieved by managing materials more efficiently.
Reduction, reuse, and recycling are primary strategies for effective reduction of waste quantities. Further, proper waste management decisions have increasing importance, as the consequences of these decisions have broader implications with respect to greenhouse gas emissions and global climate change. As a result, several public and private partnership programs are under development with the goal of waste reduction through the adoption of new and innovative waste management technologies. Because waste is an inevitable by-product of civilization, the successful implementation of these initiatives will have a direct effect on the enhanced quality of life for societies worldwide.
How is hazardous waste defined according to the Resource Conservation and Recovery Act (RCRA)? In your opinion, is this definition appropriate? Explain.
Explain specific characteristics of radioactive and medical wastes that make their management more problematic than municipal solid waste (MSW).
Compare and contrast environmental concerns with wastes in a rural versus urban setting.
What are the pros and cons of various waste management strategies? Do you agree or disagree with the general waste management hierarchy?
Explain the advantages and disadvantages of biological treatment and incineration of wastes.
Bogner, J., Ahmed, M.A., Diaz, C. Faaij, A., Gao, Q., Hashimoto,S., et al. (2007). Waste Management, In B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (Eds.), Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (pp. 585-618). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Retrieved August 19, 2010 from http://www.ipcc.ch/pdf/assessment-report/ar4/wg3/ar4-wg3-chapter10.pdf
Sharma, H.D. & Reddy, K.R. (2004). Geoenvironmental Engineering: Site Remediation, Waste Containment, and Emerging Waste Management Technologies. Hoboken, NJ: John Wiley.
In this module, a case study about electronic waste and extended producer responsibility is presented.
Electronic waste, commonly known as e-waste, refers to discarded electronic products such as televisions, computers and computer peripherals (e.g. monitors, keyboards, disk drives, and printers), telephones and cellular phones, audio and video equipment, video cameras, fax and copy machines, video game consoles, and others (see Figure Electronic Waste).
In the United States, it is estimated that about 3 million tons of e-waste are generated each year. This waste quantity includes approximately 27 million units of televisions, 205 million units of computer products, and 140 million units of cell phones. Less than 15 to 20 percent of the e-waste is recycled or refurbished; the remaining percentage is commonly disposed of in landfills and/or incinerated. It should be noted that e-waste constitutes less than 4 percent of total solid waste generated in the United States. However, with tremendous growth in technological advancements in the electronics industry, many electronic products are becoming obsolete quickly, thus increasing the production of e-waste at a very rapid rate. The quantities of e-waste generated are also increasing rapidly in other countries such as India and China due to high demand for computers and cell phones.
In addition to the growing quantity of e-waste, the hazardous content of e-waste is a major environmental concern and poses risks to the environment if these wastes are improperly managed once they have reached the end of their useful life.
Many e-waste components consist of toxic substances, including heavy metals such as lead, copper, zinc, cadmium, and mercury as well as organic contaminants, such as flame retardants (polybrominated biphenyls and polybrominated diphenylethers). The release of these substances into the environment and subsequent human exposure can lead to serious health and pollution issues. Concerns have also been raised with regards to the release of toxic constituents of e-waste into the environment if landfilling and/or incineration options are used to manage the e-waste.
Various regulatory and voluntary programs have been instituted to promote reuse, recycling and safe disposal of bulk e-waste. Reuse and refurbishing has been promoted to reduce raw material use energy consumption, and water consumption associated with the manufacture of new products.
Recycling and recovery of elements such as lead, copper, gold, silver and platinum can yield valuable resources which otherwise may cause pollution if improperly released into the environment. The recycling and recovery operations have to be conducted with extreme care, as the exposure of e-waste components can result in adverse health impacts to the workers performing these operations. For economic reasons, recycled e-waste is often exported to other countries for recovery operations. However, lax regulatory environments in many of these countries can lead to unsafe practices or improper disposal of bulk residual e-waste, which in turn can adversely affect vulnerable populations.
In the United States, there are no specific federal laws dealing with e-waste, but many states have recently developed e-waste regulations that promote environmentally sound management.
For example, the State of California passed the Electronic Waste Recycling Act in 2003 to foster recycling, reuse, and environmentally sound disposal of residual bulk e-waste. Yet, in spite of recent regulations and advances in reuse, recycling and proper disposal practices, additional sustainable strategies to manage e-waste are urgently needed.
One sustainable strategy used to manage e-waste is extended producer responsibility (EPR), also known as product stewardship. This concept holds manufacturers liable for the entire life-cycle costs associated with the electronic products, including disposal costs, and encourages the use of environmental-friendly manufacturing processes and products. Manufacturers can pursue EPR in multiple ways, including reuse/refurbishing, buy-back, recycling, and energy production or beneficial reuse applications.
Life-cycle assessment and life-cycle cost methodologies may be used to compare the environmental impacts of these different waste management options. Incentives or financial support is also provided by some government and/or regulatory agencies to promote EPR. The use of non-toxic and easily recyclable materials in product fabrication is a major component of any EPR strategy. A growing number of companies (e.g. Dell, Sony, HP) are embracing EPR with various initiatives towards achieving sustainable e-waste management.
EPR is a preferred strategy because the manufacturer bears a financial and legal responsibility for their products; hence, they have an incentive to incorporate green design and manufacturing practices that incorporate easily recyclable and less toxic material components while producing electronics with longer product lives. One obvious disadvantage of EPR is the higher manufacturing cost, which leads to increased cost of electronics to consumers.
There is no specific federal law requiring EPR for electronics, but the United States Environmental Protection Agency (USEPA) undertook several initiatives to promote EPR to achieve the following goals: (1) foster environmentally conscious design and manufacturing, (2) increase purchasing and use of more environmentally sustainable electronics, and (3) increase safe, environmentally sound reuse and recycling of used electronics.
To achieve these goals, USEPA has been engaged in various activities, including the promotion of environmental considerations in product design, the development of evaluation tools for environmental attributes of electronic products, the encouragement of recycling (or e-cycling), and the support of programs to reduce e-waste, among others.
More than 20 states in the United States and various organizations worldwide have already developed laws and/or policies requiring EPR in some form when dealing with electronic products. For instance, the New York State Wireless Recycling Act emphasizes that authorized retailers and service providers should be compelled to participate in take-back programs, thus allowing increased recycling and reuse of e-waste. Similarly, Maine is the first U.S. state to adopt a household e-waste law with EPR.
In Illinois, Electronic Products Recycling & Reuse Act requires the electronic manufacturers to participate in the management of discarded and unwanted electronic products from residences. The Illinois EPA has also compiled e-waste collection site locations where the residents can give away their discarded electronic products at no charge. Furthermore, USEPA compiled a list of local programs and manufacturers/retailers that can help consumers to properly donate or recycle e-waste.
Overall, the growing quantities and environmental hazards associated with electronic waste are of major concern to waste management professionals worldwide. Current management strategies, including recycling and refurbishing, have not been successful. As a result, EPR regulations are rapidly evolving throughout the world to promote sustainable management of e-waste. However, neither a consistent framework nor assessment tools to evaluate EPR have been fully developed.