Municipal Solid Waste
Municipal Solid Waste (MSW), often called simply trash, is made up of the things we commonly use at home and throw away, as: food scraps, packaging, old furniture, clothes, refrigerators, or grass trimmings.
The OECD definition: "Municipal waste is collected and treated by, or for municipalities. It covers waste from households, including bulky waste, similar waste from commerce and trade, office buildings, institutions and small businesses, yard and garden, street sweepings, contents of litter containers, and market cleansing. Waste from municipal sewage networks and treatment, as well as municipal construction and demolition is excluded."
For over 30 years, the U.S Environmental Protection Agency has collected information on waste generation and disposal. Every two years the Agency publishes a report on municipal waste figures – its generation, recovery achievements and disposal.
The total generation of municipal solid waste in 2015 was 262.4 million tons of MSW in 2015 61 million tons of trash were recycled while 22.1 million tons were composted, giving the total recycling rate of 33.2%. 32 million tons of garbage were combusted for energy production.
Among recovered materials, auto batteries are on the top place with the recycling rate of 99.2%. Office-type paper was recycled in 70.9%, and yard trimmings - in 64.7%. Americans managed to recycle 7 million tons of metals, which is an equivalent of removing 4.5 million cars from the road for one year.
135 million tons of trash was disposed to landfills. That is 54% of the total MSW in 2008. Significant improvement has been made comparing to the results from 1980 (89%).
Analysis of Environmental Protection Agency data reveals, that solid waste generation increased over decades from 3.66 pounds per person per day in 1980 to 4.5 in 2008. On the other hand, the recycling rate has also increased from less than 10 to more than 33%.
Sources of MSW
55-65% of the total MSW is residential waste, from houses and apartment buildings. The remaining 35-45% of the trash is produced by commercial and institutional facilities such as hospitals, schools and businesses.
The largest component of MSW are organic materials. Paper and cardboard account for 31%, yard trimmings and food scraps for 26%, and plastic for 12% of the bulk. Metals make up 8%, as does rubber, leather and textiles. Wood forms around 7%, and glass – 5 %, while other miscellaneous wastes account for 3% of the MSW.
Significants quanities of MSW were recycled and composted, with the highest recovery rates achieved in yard trimmings (64.7%), paper and cardboard (55.5%) and metals (34.6%).
About 32 million tons of materials (12.7%) were combusted for energy recovery. The combustion for energy recovery rate remains fairly constant since 1990.
Interesting fact is, that recovery for recycling did not exceed 15% until 1990. An increase in infrastructure and market demand for recovery over the last decades resulted in the growth in the recovery rate to 33.2% in 2008.
Benefits of recycling
Recycling has several environmental benefits, such as: reducing GHG emissions, which contribute to global warming, or - reducing air and water pollution associated with making new products from raw materials.
Environmental Protection Agency estimated that recycling and composting of 83 million tons of MSW saved 1.3 quadrillion Btu of energy, which is an equivalent of 10.2 billion gallons of gasoline. It reduced 183 million metric tons of CO2. This achievement is comparable to removing the emissions from 33 million passenger cars over a year.
Recycling only 1 ton of aluminum cans saves up more than 207 million Btu – the equivalent of 1665 gallons of gasoline, or 36 barrels of oil.
Other essential, but more difficult to calculate benefits of the MSW recycling are: better health of the population and more sustainable economy.
Disposing of MSW
Since 1990, the total amount of trash going to landfills dropped from 142,3 million to 135.1 million tons in 2008.
The discard rate per person per day (after recycling, composting and combustion for energy recovery) decreased from 2.51 in 1960 - when practically no recycling occurred - to 2.43 contemporary.
Municipal Solid Waste Source Reduction Initiatives
Municipal waste source reduction (or waste prevention) programs aim to change people behavior and help them to find and implement less waste-producing practices and incorporate them into an everyday routine as well as to find alternative uses for waste materials without having to dispose of or recycle them.
Since the late 1980 many states have launched initiatives aimed to reduce municipal solid waste generation. Most states are active in MSW source reduction, however the efforts vary across the country.
Ten states, including California, Colorado, Minnesota, New York and Texas have demonstrated significant commitment to MSW reduction by implementing a comprehensive municipal waste reduction action plans.
The MSW Source Reduction Program covers the 5 main areas:
- Source Reduction Planning: encouraging waste reduction through goal setting and research;
- State In-house Programs: implemented within state governments;
- Residential Programs: actions applied within the homes of residents;
- Commercial Programs: addressed to business and industrial workplaces; and
- Support for Local Governments: waste reduction through financial and
39 of the states focus primarily on commercial programs educating the business community on finding ways to reduce waste generation and reuse products.
23 of the states support residential programs. The most popular efforts includes backyard composting and consumer purchasing education campaigns.
27 states have adopted In-House programs. They focus primarily on procurement
and developing office policies on source reductions.
Successful examples of SMW source reduction initiatives include:
- Minnesota sponsored workshops on environmentally responsible purchasing for public sector employees, focusing on reduction common waste streams through responsible purchasing decisions.
- Massachusetts provided technical assistance to business through the WasteCap partnership program, which offer free consulting on source reduction to all businesses in the state.
The benefits of source reduction programs are: prevention of waste generation,
increased efficiency and enhanced conservation of natural resources.
Management and disposal of solid waste, especially unrecyclable wastes, is a critical problem in most urban communities. Landfills are one of the effective solutions to address the problem. Landfills require a good management, state of the art engineering design, and careful maintenance even after the end of their operation lifetime. The EPA reports that there are 1,269 active landfills in the US (as of 2017). This doesn't include closed landfills that no longer receive waste. About half of MSW goes to landfills. The rest is mostly recycles, composted, or incinerated.
Putting untreated waste into uncontrolled, non-engineered landfill does hurts the environment even though it is done in many places around the world. In the second half of the 20th Century “sanitary landfills” were developed to isolate waste. These are engineered to protect aquifers and have layers of soil between waste. While active, waste is regularly compacted at the landfill.
Sanitary landfills have a set features.
- Hydrogeological isolation
- A waste disposal plan and final restoration plan for when the landfill stops accepting waste
- Employees on site during the work week/ Trained operators of earth-moving equipment
- Regular compacting of newly-arived waste Covering layers of waste with soil
The American Society of Civil Engineers calls sanitary landfills "a method of disposing of refuse on land without creating nuisances or hazards to public health or safety, by utilizing the principles of engineering to confine the refuse to the smallest practical area, to reduce it to the smallest practical volume, and to cover it with a layer of earth at the conclusion of each day's operation, or at such more frequent intervals as may be necessary."
The US Department of Agriculture names three methods of sanitary landfills. The area method is where wastes are spread, followed by compaction, and then followed by soil covering. A mound builds up over the natural land contour which started as relatively flat. The trench method involves digging a trench in the existing land and burying the waste. There is also the slope method where waste is deposited on a natural slope, essentially evening out the surface contour.
When compacted, the waste in landfills can reach a density of 600 kg per cubic meter. By contrast water weighs 1000 kg per cubic meter and soil is typically 1800 kg per cubic meter.
At the bottom of the landfill is a liner, designed to retard leakage of liquid to the groundwater. These geomembranes are made from plastic. In some engineered facilities, a layer of clay is also used to line the bottom. Combinations of multiple plastic lines and clay lawyers may be employed.
Costs for businesses to dispose of waste in landfills varies widely by area of country. The US EPA says the average cost in 2019 was $55.36 per ton.
New York Department
of Environmental Conservation
Zero Waste Skepticiam
India's Ministry of Environment and Forests Central Pollution Control Board
Germany on a Recovery Mission
Facts about Municipal Solid Waste
Solid Waste Association of North America
Meghalaya State Pollution Control Board
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