A bag of trash here. A bag there. What you set out curbside each week for the waste hauler to tote away may not seem like a lot, but multiply that by every household in America and your manageable pile literally grows into a mountain. Indeed, each American (over 300 million strong) tosses approximately 4.6 pounds of garbage every day; more than the residents of any other country.
In 2006, Americans generated over 251 million tons of municipal solid waste (MSW), up from about 246 million tons the year before. Of that, 32.5 percent is recycled or composted, 12.5 percent is burned at combustion facilities, and the 55 percent leftover is tossed into landfills.
Paper represents the largest portion of solid waste generated in the US by far—over one-third of the solid waste generated in the US in 2006 was paper products. Yard trimmings represent the next largest portion (12.9 percent in 2006), followed by food waste (12.4 percent in 2006), plastic waste (11.7 percent in 2006), metal waste (7.6 percent in 2006), and rubber, leather, and textile waste (7.3 percent). Glass and wood each represented less than 6 percent of the municipal solid waste generated in 2006.
Methods of garbage disposal: Eco-best to worst
Reducing waste at the source is the the most environmentally sustainable approach to solid waste management. Reducing the amount of waste produced is also known as waste minimization, source reduction, or waste prevention. Waste reduction requires the disposal of less waste, which provides a host of direct environmental benefits. Fewer resources are used and less energy is consumed collecting, transporting, sorting, processing, storing, and disposing of the waste. Indirect benefits exist as well, since fewer resources and less energy is consumed.
There are a variety of approaches to reducing waste, ranging from creating products with less packaging to building more durable products with longer useful lives. Reducing the overall amount of waste produced is the most environmentally friendly approach to managing our solid waste.
Reusing objects to prevent them from becoming garbage is the next most sustainable approach to solid waste management. Reusing items is more sustainable than recycling them or otherwise disposing of them, since the items do not require energy or other resources to collect, transport, sort, and either process into their constituent recyclable components, incinerate, or sequester in a landfill. Reusing items has the added indirect environmental benefit of conserving the energy and other resources necessary to manufacture a new product.
Like waste reduction, reuse can be approached in different ways. The ability to reuse items often requires an upfront purchasing decision, such as purchasing a reusable coffee mug rather than using disposable coffee cups. Many objects like used clothing that would otherwise become garbage can be reused by others through donation and redistribution programs.
Recycling turns an object that would otherwise need to be disposed of into a usable resource. Different than reuse, recycling typically involves breaking down and processing the waste objects into new materials.
Recycling is a more sustainable way of dealing with solid waste than incineration or putting it in a landfill, but it has drawbacks when compared with waste reduction and reuse strategies. For example, recycling still requires the energy and other resources necessary to collect, transport, sort, and process the recyclable waste.
Recycling does, however, save energy and resources required to create new materials, and helps to minimize harmful practices like strip mining and clear cutting. For example, recycling aluminum instead of mining and processing virgin ore results in energy savings of up to 95 percent; recycling plastics can reduce energy consumption by 70 percent, and recycling steel reduces energy consumption by 60 percent. Recycling paper and glass saves less energy, resulting in energy savings of 40 and 30 percent respectively. And, recycling keeps waste out of landfills. In 2006, recycling, including composting, resulted in diverting 82 million tons of material away from landfills and incinerators, up from 34 million tons in 1990.
Since some materials, like aluminum, can be recycled locally over and over indefinitely, the costs of transporting raw materials long distances for manufacturing can be reduced or eliminated as well. Recycling even plays a role in reducing emissions of climate-changing greenhouse gases. Recycling programs are estimated to have kept the equivalent of 39 million car's worth of carbon out of the atmosphere in 2006, saving the equivalent of 10 billion gallons of gasoline.
A key factor in the viability of recycling programs is demand for recycled products. When consumers purchase products made from recycled materials, they are not only saving valuable natural resources and energy, but are also supporting necessary markets for recycled materials.
Composting is the breakdown or controlled decomposition of some types of organic waste through naturally-occurring biological processes. Composting is considered a form of recycling but can be done at home, which prevents the waste from ever entering a municipal solid waste program, saving energy and resources. One-quarter of the municipal solid waste stream in the US is food and yard waste, which could be turned into compost and kept out of landfills and incinerators. In 2006, 21 million tons of waste (62 percent of yard trimmings and 2.2 percent of food waste) were composted by municipalities, representing about 8 percent of the MSW generated in the US. In 2006, 3,470 community composting programs were operational, up from 3,227 in 2002.
Compost, like other recycled materials, can be a valuable commodity—high-quality compost prices can reach as high as $100 per ton, which helps support the expansion of composting programs. Compost use is a critical part of the success of organic farming techniques, as compost reduces the need for chemical fertilizers, pesticides, and herbicides. Composting can also be a valuable tool in cleaning up contaminated soil and removing toxins from the environment. Composting can treat volatile organic compounds (VOCs), polyaromatic hydrocarbons (PAHs), and can degrade or eliminate pesticides, wood preservatives, and chlorinated and non-chlorinated hydrocarbons in contaminated soils.
Incineration, or combustion of solid waste in municipal incinerators, is another way that many localities handle solid waste. While incineration is not as environmentally-sustainable as the waste management techniques listed above, it helps to substantially reduce the volume, weight, and toxicity of municipal solid waste. In fact, incineration can reduce the volume of solid waste by up to 90 percent, and can reduce the weight by 75 percent. The extremely high temperatures achieved in incineration can also kill dangerous pathogens and destroy toxic chemicals in the solid waste. However, incinerating MSW produces dangerous air pollution in the form of nitrogen oxide, sulfur dioxide, mercury, and dioxins, as well as releasing large amounts of carbon dioxide.
Incinerating MSW also leaves behind waste ash, and disposing of this ash is another environmental challenge. The main constituents of ash are silicon dioxide, calcium dioxide, iron oxide, and aluminum oxide. However, ash from MSW combustion can also contain the hazardous elements that were present in the original solid waste. Because of this, the ash must be tested regularly to determine if it contains hazardous materials. If it does, it must be disposed of in special facilities to prevent ground-water contamination. Ash deemed non-hazardous may be recycled and used in pavement for parking lots and roads, but is usually disposed of in landfills.
Waste-to-energy incineration facilities
Solid waste can also be incinerated in waste-to-energy (WTE) facilities that generate electricity. Since only waste materials are used in these facilities, they are sometimes considered a renewable energy resource—so long as we continue to produce waste that cannot be recycled or composted, there will be fuel for these facilities. In 2006, about 31.4 million tons of waste materials, or 12.5 percent of the total MSW, were burned for energy recovery. There are 87 WTE plants operating in the US, which handle more than 90,000 tons of trash daily and supply electricity to about 2.3 million homes across the country. Newer technologies like plasma-arc gasification, which vaporize waste at temperatures of over 10,000 degrees Fahrenheit, promise to cleanly dispose of waste while generating electricity with fewer emissions than even natural gas generators. These facilities have not yet proven to be as environmentally-friendly as their proponents have argued, however.
Like fossil fuel-powered plants, WTE plants require fresh water for operations, which is taken from local rivers or lakes and in the process disrupts or kills aquatic wildlife. They also generate waste water, which may contain pollutants and therefore typically require monitoring. Because the waste water is much warmer upon discharge than uptake, it can disrupt or kill local aquatic wildlife as it is reintroduced after usage, causing further harm.
Solid waste landfills are the final destinations for the MSW that has not been recycled, composted, or incinerated. Over 138 million tons of solid waste were interred in landfills in 2006, down from nearly 143 million tons in 1990. There are numerous types of landfills, but they can basically be broken down into two varieties: containment landfills and attenuation and dispersal landfills. Containment landfills are also sometimes referred to as sanitary landfills, and are designed to keep wastes, waste leachates, and gases out of the surrounding environment. Attenuation and dispersal landfills are usually older facilities that are basically "dumps," and have little or no features engineered into them to prevent local environmental pollution. These types of facilities are becoming uncommon today and are being phased out in the US and Europe.
Bioreactor landfills are a type of containment landfill designed to more rapidly decompose organic waste in garbage, but do not attempt to create compost. By injecting additional air, moisture, or both, bioreactor facilities use aerobic and/or anaerobic decomposition to hasten the normal waste degradation processes. This approach is different than that used in entombment or dry tomb landfills that are effectively long-term storage facilities for garbage and do not encourage decomposition. Natural gas or methane, a greenhouse gas produced in the decomposition process, can be captured from both bioreactor and dry tomb landfills and used to generate electricity.
Household hazardous waste
Household hazardous waste, or HHW, consists of products like pesticides, batteries, cleaners and solvents, paint, and oils. Each year, 1.6 million tons of HHW is generated in the US. The US Environmental Protection Agency (EPA) maintains a list of common HHW products that warrant special disposal practices to prevent injuries to sanitation workers and contamination of soil, groundwater, or wastewater facilities. Federal law allows for the disposal of HHW in the trash, but some states like California prohibit disposal of HHW with normal garbage.
Many local municipalities operate a dedicated collection facility where these products can be exchanged or deposited for disposal, or offer special collection days for curbside pick-up or drop-off at a central location. If your local government doesn't offer HHW disposal or collection programs, local businesses may be able to accept certain materials—garages are required by law in some states to accept used motor oil, for example, and some retailers will recycle used batteries.
Never dispose of household hazardous waste inappropriately, such as burying it, pouring it down drains, or burning it. You may be breaking the law and the environmental consequences can be severe.
Viability of recycling programs
The controversies surrounding solid waste creation, management, and disposal are as diverse as the constituents of garbage itself. Recycling, for example, has been a highly controversial subject. Recycling opponents argue that recycling costs more than incineration or dumping trash in landfills, and that much of the supposedly "recycled" waste is incinerated or dumped anyway. Recycling proponents argue that recycling does not usually cost more (a view the EPA) endorses), and that it would be worth an extra cost to keep more materials out of landfills and incinerators.
In perhaps the most famous example of this controversy, New York City Mayor Michael Bloomberg suspended plastic and glass recycling in 2002, claiming that it would save the city $40 million dollars in waste management and disposal costs in 2003. However, those savings did not materialize, as new markets for recycled materials drove up demand and lowered (or eliminated) the costs for collection, and landfills closed and raised the costs of dumping recyclables. New York City began recycling plastic and glass again in 2004 and today saves money due to its comprehensive recycling programs.
While the controversy continues over whether there are tangible environmental benefits associated with recycling, there is substantial evidence that, in most cases, it is preferable to incineration or disposal of garbage in landfills. The British firm Waste & Resources Action Programme (WRAP) worked with the Danish Topic Centre on Waste and the Technical University of Denmark to analyze the life-cycle of waste and the possible outcomes associated with various disposal methods. After studying more than 200 different possible scenarios that contrasted recycling with incineration or burying, they concluded that in 83 percent of the cases that included recycling, it was positive for the environment.
Another controversy that has arisen associated with recycling is the practice of shipping recyclables to China. While there is little doubt that these materials are indeed being recycled, there are health and environmental issues surrounding how many waste objects are handled. For example, electronics and plastic products can release toxins into the environment if not handled properly. While the Chinese government has restricted how these materials are to be handled, enforcement is lax.
- dioxins: Among the most toxic known chemicals with no safe exposure level, dioxins are typically formed in waste incineration processes, backyard waste burning, chemical manufacturing, and paper pulp bleaching.
- mercury: A heavy metal that can accumulate in tissue and may cause brain and kidney damage, especially in children.
- methane: A naturally occurring flammable gas that is a potent greenhouse gas, over 20 times more effective at trapping heat in the atmosphere than CO2.
- nitrogen oxides: Gases that contain nitrogen and oxygen produced during fuel combustion, such as in motor vehicles and electric utilities, these compounds can react to form smog, acid rain, and particulate matter when released and exposed to sunlight and other gaseous compounds in the atmosphere.
- sulfur dioxide: A chemical compound created by combustion processes, sulfur dioxide can create acid rain and acidify waterways as it dissolves.
- volatile organic compounds (VOCs): Organic solvents that easily evaporate into the air, VOCs are considered a possible carcinogen and can create ground-level ozone, the main component of smog.
- Learner.org - Garbage
- US Environmental Protection Agency - Municipal Solid Waste
- The Rotten Truth About Garbage - A selection of online resources
- US Environmental Protection Agency - Municipal Solid Waste Basic Facts
- US Environmental Protection Agency - Municipal Solid Waste Generation, Recycling, and Disposal in the United States: Facts and Figures for 2006
- The Economist - The Truth About Recycling
- US Environmental Protection Agency - Reduce, Reuse, and Recycle
- US Environmental Protection Agency - Composting
- Integrated Waste Services Association - Waste-to-Energy
- US Environmental Protection Agency - Solid Waste