Waste management

BACKGROUND

Waste management involves collecting, transporting, processing, and monitoring waste materials that are typically produced by human activities. It may involve recycling, destroying, or relocating waste. Waste management may help maintain sanitary conditions, protect the environment through proper waste-removal practices, and uphold aesthetic standards in a community. Waste management may involve solid, liquid, gaseous, or radioactive substances. Examples of liquid waste include wastewater (water contaminated by domestic residences, commercial properties, industry, and/or agriculture) and sewage (typically includes feces and urine as well as domestic, municipal, and industrial liquids). Examples of gaseous wastes include carbon monoxide and radiation; they may be produced by human biological processes, manufacturing, material processing, consumption of goods, or other human activities.

Waste management practices differ among areas, communities, and countries. For example, different disposal practices are used in developed and developing nations, urban and rural areas, and residential and industrial communities. Waste management may fall under the responsibility of the local government, particularly in the case of residential waste, or it may fall under the responsibility of private individuals and organizations, such as is the case with commercial and industrial waste.

Worldwide figures for municipal wastes vary considerably due to inconsistent statistics and definitions. Municipal solid wastes (MSW) are discarded materials resulting from residential and non-industrial operations and activities. In general, MSWs constitute about 14-20% of all wastes generated worldwide. Other common waste types include: construction and demolition wastes (30%), manufacturing (20%), and mining and quarrying (23%). Per capita generation of waste varies; changing lifestyles, ineffective policies, and lack of awareness may cause this rate to increase exponentially over the next decade. However, increased recycling programs and awareness may cause these rates to steady or decline.

Waste management may involve both hazardous and non-hazardous materials. Non-hazardous materials most often become hazardous when contaminated with chemicals. Contamination may occur during production, storage, transportation, use, or disposal of chemicals. Hazardous materials in various forms may cause death, serious injury, long-lasting health effects, and damage to buildings, homes, and other property.

Many products containing hazardous chemicals are used and stored in homes routinely and are also shipped daily on the nation's highways, railroads, waterways, and pipelines. Sources of hazardous materials include chemical manufacturers, service stations, hospitals, and hazardous materials storage sites. Hazardous materials may include: explosives, flammable and combustible substances, poisons, pharmaceuticals, and radioactive materials; they are most often contained but may be released as a result of transportation accidents or because of chemical accidents in plants.

Waste management is also necessary for biohazardous waste, which is also called infectious waste or biomedical waste. Biohazardous waste is classified as any waste containing infectious materials or potentially infectious substances. Types of biohazardous waste include human blood and blood products, human body fluids, biological laboratory wastes, pathological (human tissues, organs and body parts) waste, and animal waste. Of special concern is sharps waste, such as needles, blades, and glass pipettes.

Negative consequences of poor waste management may include oil spills, improper disposal of toxic waste, and waste disposal incidents. Such incidents may cause contamination of surface and ground waters, including drinking water, high cleaning and containment costs, acute poisoning, the release of cancer-causing agents, and an increased occurrence of miscarriages and birth defects.

Landfills are the most common form of organized waste management. About 57- 85% of the wastes generated worldwide are disposed in open and engineered landfills. Negative effects of landfills may include: fatal accidents, infrastructure damage, pollution of the local environment (such as contamination of groundwater and the destruction of local wildlife habitats), offgassing (the release of gases into the air) of methane generated by decaying organic wastes, harboring of disease-carrying agents such as rats and flies, dust, odor, and noise pollution. Positive aspects of landfills include: they are inexpensive, they create local jobs, they may host a variety of wastes, the gases emitted from the landfill may be used to create energy, reduced transportation fees for the waste, and the problem of waste is dealt with locally instead of being outsourced.

There are government-enforced laws and regulations in the United States for waste management. Currently, there are numerous laws to protect human health and the environment. These laws give the U.S. Environmental Protection Agency (EPA) most of its authority to write regulations and to serve as the foundation for achieving the nation's environmental and public health protection goals. The EPA is considered a regulatory agency because Congress authorizes it to write regulations that explain the critical technical, operational, and legal details necessary to implement laws.

Each year, the EPA issues about 130 substantive regulations that apply nationwide. Of these regulations, only about 5-10 are considered major, meaning they have the potential to impose cumulative costs of more than $100 million a year. In addition, the EPA publishes about 900 proposed regulations, technical corrections to existing regulations, State Implementation Plans (SIPs), and other information-related to the enforcement and implementation of existing regulations.

Although the EPA believes that regulations play an irreplaceable role in environmental and public health protection, there are some circumstances where alternatives may be used. Some of these alternatives are voluntary partnership programs, economic incentives, and technical assistance.

TECHNIQUE

General: Waste management may include disposal and/or recycling methods. Disposal methods include use of landfills and incineration. Recycling processes include biological reprocessing, energy recovery, and avoidance and reduction methods.

Landfills: Waste is most often buried in landfills, which are often established in abandoned or unused quarries, mining voids, or borrow pits (excavated areas). Properly-designed and well-managed landfills are a hygienic and relatively inexpensive method of disposal of waste materials. Older, poorly designed or poorly managed landfills may create a number of adverse environmental problems.

Wind-blown litter, attraction of vermin, and generation of liquid leachate are some consequences of improper landfills. Leachate is the liquid that drains or 'leaches' from a landfill.

Another common byproduct of landfills is gas, which is mostly composed of methane and carbon dioxide. Gas is produced as organic waste breaks down anaerobically. This problem is called "offgassing," and it may create odor problems, kill surface vegetation, and contribute to the greenhouse effect.

Well-designed modern landfills include methods to contain leachate, such as using clay or plastic-lining material. Additionally, deposited waste may be compacted to increase its density and stability and then covered to prevent attracting vermin, such as mice or rats. Many landfills have landfill gas extraction systems installed to pump the gas out of the landfill using perforated pipes; the gas can then be flared off or burnt in a gas engine to generate electricity.

In certain areas of the United States, space for landfills is becoming scarce, particularly as rural areas become more densely populated. Many communities oppose construction of new landfills near homes.

Incineration: During the process of incineration (also called thermal treatment), waste material is burnt and may be reduced by about 70-90%. Waste-to-energy (WtE) and energy-from-waste (EfW) are both broad terms for facilities that burn waste in a furnace or boiler to generate heat, steam, and/or electricity. Well-designed incinerators that include material separation can successfully eliminate hazardous waste and generate electricity with minimal damage to the environment. Incineration is common in countries where land is more limited because incineration facilities generally do not require as much area as landfills.

Incinerators convert waste materials into heat, gas, steam, and ash. The heat, gas, and steam are often released into the environment or used to generate electricity. The leftover ash, which is also called incinerator bottom ash, may be processed (to standardize the material and remove contaminants) and used in bulk fill, asphalt, cement-bound materials, lightweight blocks, pavement, and fertilizer. If there are no local markets for the ash, it is typically disposed of in a landfill or it may be monofilled (monofills are single-use landfills used for homogeneous material storage) or treated as hazardous waste.

Incineration may be carried out on a small scale by individuals or on a large scale by industry to dispose of solid, liquid, and gaseous waste. It may be a practical method of disposing of certain hazardous waste materials, such as biological medical waste. However, incineration is a controversial method of waste disposal because the emission of gaseous pollutants may contribute to global warming. Concern has been focused on some very persistent organics, such as dioxins, that may be created within the incinerator and may have serious environmental consequences in the area immediately surrounding the incinerator. Dioxins are known to be harmful to humans and may cause cancer and hormonal problems.

Biological reprocessing: Biological composting and digestion processes, also called biological reprocessing, may be used to decompose organic matter, such as plant material, food scraps, and paper products. The resulting organic material may then be recycled as mulch or compost and used for agricultural or landscaping purposes. Additionally, waste gas from the process, such as methane, may be used to generate electricity.

Biological processing aims to control and accelerate the natural process of the decomposition of organic matter. Composting and digestion methods and technologies vary in complexity from simple home compost heaps to industrial-scale enclosed-vessel digestion of mixed domestic waste. Methods of biological decomposition may be classified as aerobic (dependent upon oxygen) or anaerobic (lacking oxygen) methods; hybrids of the two methods also exist. As interest in environmental responsibility grows, more households are employing this method of waste removal. Evidence on negative environmental impact is lacking.

Energy recovery: Proper waste management may result in energy recovery processes. The energy content of waste products may be harnessed directly as a combustion fuel or indirectly by processing into another type of fuel. For example the waste from an incinerator may be used as a fuel source for cooking or heating or may fuel boilers to generate steam to turn a turbine. In the latter case, the heat generated from the burning waste produces electricity.

Avoidance and reduction: Waste is best managed through waste prevention, education, and practice. Waste reduction or avoidance processes may include: reusing products, repairing broken items instead of buying new ones, designing new products to be refillable or reusable (such as reusable shopping bags), encouraging consumers to avoid using disposable products (such as plastic silverware and paper cups), and designing products that use less material to achieve the same purpose.

The U.S. Environmental Protection Agency (EPA) is constantly analyzing and developing new ways to best manage waste to have a minimal impact on the environment. Education continues to play a central role in making waste management more safe and effective. Consumers who want to improve the waste management methods in their communities may contact their local government, work with the EPA, and/or consult local and federal guidelines.

Biodiesel: Converting food waste into energy is a process that has recently gained interest in efforts to reduce nation's carbon footprints. Biodiesel is used to power automobiles, trains, airplanes, and home-heating systems by capturing energy released from the breakdown of lipids in foods. By blending these products with hydrocarbon-based diesel, they can be safely used in conventional diesel engines.

Recent green efforts have helped make biodiesel more efficient and easier to obtain for consumers. Following the Energy Policy Act of 2005, an act that provided provisions to corporations addressing environmental concerns, car manufacturers have introduced models that are specifically designed for biodiesel. Biodiesel research continues to advance to provide alternative options in the collaborative effort to minimize harmful effects on the environment.

THEORY/EVIDENCE

Extended producer responsibility (EPR): EPR is a strategy designed to promote the integration of all costs associated with products throughout their life cycle, such as the end-of-life disposal costs, into the market price of the product. This is meant to impose accountability over the entire lifecycle of products. Firms that manufacture, import, and/or sell products are held responsible for the products after their useful life.

Integrated solid waste management: Integrated solid waste management is an approach that includes a combination of waste prevention, waste reduction, and disposal techniques to effectively manage the problem of municipal solid waste. Consumers are encouraged to reduce, reuse, recycle, and compost waste materials so that fewer materials will appear in the waste stream destined for landfills or incinerators.

Polluter pays principle: The Polluter Pays Principle requires the polluting party to pay for the impact caused to the environment. Typically, a waste generator is required to pay for the appropriate disposal of the waste. This is difficult to prove and, therefore, difficult to enforce. However, the U.S. Environmental Protection Agency (EPA) and other organizations are working to make regulations and guidelines more strict and consequential.

Waste hierarchy: The waste hierarchy refers to the "three Rs:" reduce, reuse, and recycle. The waste hierarchy is the best strategy for waste avoidance and reduction.

HEALTH IMPACT/SAFETY

General: The indiscriminate and improper dumping of waste raises several serious environmental issues, including loss of renewable resources such as metals, plastic, glass, and the loss of potential resources such as compost from organic waste, and energy from burnable waste. Other concerns include: the contamination of land and water bodies from the discharge of leachate and other hazardous materials, air pollution caused by the emissions from burning, and air pollution caused by the release of methane from anaerobic decompositions. Risks to human health include respiratory problems, skin problems, and the spread of diseases by vermin near landfill sites.

Landfills: Methane gas, leachate, and loose waste are the three main causes of negative health/safety effects. Methane gas is produced in landfills by anaerobic decomposition. To prevent health hazards, it can be collected and used to generate electricity or it can be purified and used as a fuel. Methane is not toxic; however, it is highly flammable and may form explosive mixtures with air if not managed properly.

Leachate is a thick liquid that forms when garbage decomposes. It may carry hazardous materials with it, such as toxic metals and organics that were dissolved from the waste. The leachate may get into nearby water sources, such as rivers, and contaminate them, severely diminishing biodiversity and greatly reducing populations of sensitive species. To solve this problem, newer landfills have synthetic liners above a clay-like soil that help to prevent the leachate from leaking into the groundwater and causing contamination.

Loose waste attracts disease-carrying vermin. It may also become airborne and cause land pollution. Covers may be installed over landfills to minimize these problems. Once the landfill stops accepting waste, a final multi-layer cover must be applied to keep liquids away from the waste, and vegetation is planted to reduce the effects of erosion.

Medical/biohazardous waste: Healthcare institutions often generate hazardous and infectious waste. Improper disposal of dangerous microorganisms pose a serious health risk for patients and personnel. Healthcare institutions must go through strict processes of collection, documentation, storage, transport, and neutralization of waste to avoid potential health risks. These processes vary among organizations and institutions.

Biohazardous waste, which is also called infectious waste or biomedical waste, is classified as any waste containing infectious materials or potentially infectious substances. Types of biohazardous waste include: human blood and blood products, human body fluids, biological laboratory wastes, pathological (all human tissues, organs, and body parts) waste, and animal waste. Of special concern is sharps waste such as needles, blades, glass pipettes, and other wastes that can cause injury during handling.

Pharmaceutical wastes (such as unused pills) pose a hazard because they contain highly concentrated chemicals that may contaminate local water supplies if disposed of improperly. The U.S. Environmental Protection Agency (EPA) has proposed to add hazardous pharmaceutical wastes to the Universal Waste Rule in order to provide a system for disposing hazardous pharmaceutical wastes that is protective of public health and the environment. The EPA believes that this proposed addition will make it easier for generators to collect and properly dispose of these items as hazardous wastes, resulting in a simpler and more streamlined waste management system.

FUTURE RESEARCH OR APPLICATIONS

General: Education and awareness in the area of waste and waste management are crucial to improving future waste management.

Education: The Talloires Declaration is a declaration for sustainability concerned about the unprecedented scale and speed of environmental pollution and degradation and the depletion of natural resources. Composed in 1990 at an international conference in Talloires, France, this is the first official statement made by university administrators of a commitment to environmental sustainability in higher education. The Talloires Declaration is a 10-point action plan for incorporating sustainability and environmental literacy in teaching, research, operations, and outreach at colleges and universities. It has been signed by more than 350 university presidents and chancellors in more than 40 countries. Samples of the points include: (1) to increase awareness of environmentally sustainable development, (2) to create an institutional culture of sustainability, and (3) to educate for environmentally responsible citizenship.

Waste reduction: The best way to manage waste in the future is to reduce waste production now. Activities that can be done to reduce the amount of waste generated include: following the community's recycling program, composting yard and organic wastes, mulching leaves and grass clippings, buying recycled products and products with less packaging, buying durable products rather than disposable ones, reusing products, and repairing broken/worn items instead of buying new ones. There are both federal and state laws in the United States to regulate waste management. The federal laws include: CERCLA/SARA - Superfund, RCRA-D (SW Subchapter IV), RCRA-C (HW Subchapter III), and RCRA (UST Subchapter IX).

Accelerating decomposition: The principle organisms involved in decomposition are bacteria and fungi. These organisms are collectively called "decomposers" for their role in breaking down dead organic material from plants and animals and their waste products. This process is vital for maintaining conditions suitable to sustain life on Earth; carbon dioxide is returned to the atmosphere from decaying plant matter and sewage is undergoing constant recycling, which prevents septic waste from accumulating.

The rate of decomposition is dependent on a number of factors. First, microbiological organisms must be present in order for the decomposition process to occur. Adding a handful of finished compost or garden soil is enough to introduce many of these organisms. Most microorganisms responsible for decomposition are aerobes, meaning that they require oxygen to survive. Aerating the pile to allow for larger numbers of bacterial growth can encourage a faster decomposition process. Moisture can also facilitate colonization of bacteria, and for rapid decomposition to occur, water can be added to the pile.

AUTHOR INFORMATION

This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

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