1. ENVIRONMENTAL SCIENCE
14th Edition
A Study of Interrelationships

2. Outline 18.1 Kinds of Solid Waste 18.2 Municipal Solid Waste
18.3 Methods of Waste Disposal

3. 18.1 Kinds of Solid Waste
Solid waste is generally made of objects or particles that accumulate on the site where they are produced.
They are typically categorized by the sector of the economy responsible for producing them.

4. 18.1 Kinds of Solid Waste Mining wastes are generated in three ways:
Waste material is left on the surface
Milling tailings are dumped on the land or stored in ponds.
Waste or tailings drainage often contains hazardous materials.
Agricultural waste
Includes waste from raising animals as well as crop and tree harvesting.
90% is used as fertilizer or other forms of soil enhancement.

5. 18.1 Kinds of Solid Waste
Industrial solid waste consists of solid waste other than mining.
Estimated to be between million metric tons annually.
Demolition waste
Sludge
Combustion ash
Municipal solid waste consists of all the materials people in a region no longer want.
210 million metric tons annually.

6. 18.2 Municipal Solid Waste
Some items are discarded when they are broken or worn out.
Other products like magazines, catalogs, newspapers, packaging, bottles, and cans are temporarily useful and then are discarded.
Those that have only temporary uses make up the majority of the solid waste stream.

7. 18.2 Municipal Solid Waste
The Unites States produces nearly 230 million metric tons of municipal solid waste annually.
This equates to 2 kg (4.4 lbs) of trash per person per day.
Per capita waste has increased 70% since 1960.

8. Municipal Solid Waste Generation Rates

9. 18.2 Municipal Solid Waste
Nations with a higher standard of living tend to produce more municipal solid waste per person than less-developed countries.
Large metropolitan areas have the greatest difficulty dealing with solid waste.

10. Waste Generation and Lifestyle

11. The Changing Nature of Trash

12. Composition of Trash in the United States 2011

13. 18.3 Methods of Waste Disposal
In the past, the favored means of waste disposal was to dump solid wastes outside of city or village limits.
To minimize the volume of waste, the dump was often burned.
This practice is still employed in remote or sparsely populated areas in the world.

14. Burning Landfills

15. 18.3 Methods of Waste Disposal
Five techniques are now used in waste disposal:
Landfills
Incineration
Source reduction
Composting
Recycling

16. Changes in Waste Disposal Methods

17. Landfills
A municipal solid waste landfill is typically constructed above an impermeable clay layer, lined with an impermeable membrane.
It includes mechanisms for dealing with liquid and gas materials generated by the contents of the landfill.
Traditionally this has been the primary method of waste disposal.
Cheap and convenient
Problems associated with poorly designed landfills have been recognized, and substantial efforts are made to reduce the amount of waste entering landfills.

18. Landfills
New landfills have an impermeable liner and complex bottom layers to trap contaminant-laden leachate.
Monitoring systems are necessary to detect methane gas production and groundwater contamination.
In some cases, methane is collected and used to generate electricity.
New landfills currently cost up to $1 million per hectare ($400,000 per acre) to prepare.

19. A Well-Designed Modern Landfill

20. 18.3 Methods of Waste Disposal
The number of landfills is declining.
Many small landfills that were not meeting regulations have been closed.
Capacity has been reached.
New landfills often resisted due to public concerns over groundwater contamination, odors, rodents, and truck traffic.

21. Reducing the Number of Landfills

22. Incineration
Incineration is the process of burning refuse in a controlled manner.
Currently, about 12% of U.S. municipal solid waste is incinerated.
Most incinerators are designed to capture heat, which is then used to make steam to produce electricity.
The production of electricity partially offsets disposal costs.
Most incinerators burn unprocessed municipal solid waste. This process is referred to as mass burn technology.

23. Incineration
Incinerators drastically reduce the amount of municipal solid waste.
Up to 90% by volume and 75% by weight.
Primary risks of incineration involve air quality problems and toxicity and disposal of ash.
Toxic substances are more concentrated in ash.

24. Incineration
Even with modern pollution controls, small amounts of pollutants are still released into environment.
The cost of land and construction for new incinerators are also major concerns facing many communities.
Construction costs in North America in 2010 ranged from $50-$400 million.

25. Incineration
U.S. EPA has not looked favorably on construction of new waste-to-energy facilities.
It has encouraged recycling and source reduction as more effective solutions to deal with solid waste.

26. Disposal Methods Used in Various Countries

27. Composting
Composting uses natural processes of decomposition to transform discarded organic materials—grass clippings, leaves, food waste, or soiled paper—into compost, a humus-like material.
With proper management of air and water, composting can transform large quantities of organic material into compost over a short period of time.
Small-scale composting can be accomplished in the backyard, mixing green materials (grass clippings, vegetable scraps, etc.) and brown materials (dry leaves, twigs, soiled paper towels).

28. Diverting Yard Waste Through Composting

29. Composting
About 3,800 composting facilities are currently in use in the United States.
Most municipal programs involve one of three composting methods:
Windrow systems
Aerated piles
Enclosed vessels

30. Source Reduction
The simplest way to reduce waste is to prevent it from ever becoming waste in the first place.
Source reduction is the practice of designing, manufacturing, purchasing, using and reusing materials so that the amount of waste or its toxicity is reduced.

31. Source Reduction Design changes
Since the 2-liter soft drink bottle was introduced in 1977, weight has been reduced by 25%.
As a result, 250 million pounds of plastic have been kept out of the waste stream.
Manufacturing processes reduce waste and increase efficiency.
Purchasing decisions
Choose reduced packaging and plan quantities accordingly.

32. Source Reduction Using materials to avoid waste generation
Reduce use of hazardous materials.
Follow label directions carefully and use the smallest amount necessary.
Reusing items
Delay or prevent entry of items into waste collection stream.

33. Source Reduction
Most businesses and manufacturers have a strong economic incentive to ensure they get the most from all materials they use.
Any activities that reduce the amount of waste produced, reduce the:
Cost of waste disposal
Amount of raw materials needed
Amount of pollution generated

34. Recycling
Recycling is one of the best environmental success stories of the late 20th century.
In the United States, recycling (including composting) diverted about 35% of solid waste stream from landfills and incinerators in 2011.

35. Recycling
Beverage Container Deposit-Refund programs provide an economic incentive to recycle.
Disposable containers are an increasing problem.
In 1990 the average US citizen disposed of 550 drink containers.
In 2010 this had risen to 784, about a 43 percent increase.
Beverage containers currently constitute 25 percent of household trash.
In a deposit-refund program a cash value in the form of a deposit is placed on the glass, aluminum, or plastic beverage container.
Thus, consumers have an incentive to return their containers for the redemption value.

36. Recycling
All provinces and most territories in Canada and at least 12 countries in Europe have bottle bills.
In the United States, 10 states currently have beverage container deposit laws.
They have recycling rates of 70 percent or more on containers covered by their laws.
The average for the United States is about 35 percent.

37. Recycling
Mandatory recycling laws provide a statutory incentive to recycle.
Many states and cities have passed mandatory recycling laws.
Some of these laws simply require that residents separate their recyclables from other trash.
Some are aimed at businesses and require them to recycle certain kinds of materials such as cardboard or batteries.
Some forbid the disposal of certain kinds of materials in landfills.
Those states and cities with mandatory recycling laws understandably have high recycling rates.

38. Recycling Rates

39. Recycling
Curbside recycling provides a convenient way for people to recycle.
In 1990, 1,000 U.S. cities had curbside recycling programs.
In 2011, 9,800 programs served 70 percent of the U.S. population. .
Cities with curbside recycling tend to have much higher recycling rates than cities that lack such programs.

40. Recycling
In the U.S., curbside pick-up of recyclables is increasingly the norm, but rates remain low.
Recycle Bank was founded in 2004.
Families on a garbage route are issued a container with a computer chip. Recyclables are weighed and the family earns points redeemable at merchants like CVS pharmacy.
Recycle Bank launched in Philadelphia in 2006.
Recycle rates rose from 7% to 90%.
In 2008 Recycle Bank started a pilot program in N.Y at Columbia University.
Students recycle and claim their points.

41. Recycling Challenges
There are many technical and economic problems associated with recycling.
Plastics are recyclable, but technology differs from plastic to plastic.
Milk containers tend to be high-density polyethylene (HDPE), while egg containers are polystyrene (PS), and soft-drink bottles are polyethylene terephthalate (PET).

42. Increasing Amounts of Plastics in Trash

43. Recycling Challenges
Plastic bags are a convenience, a nuisance, and an environmental hazard. They are handy to carry items from the store.
Many marine organisms such as turtles, whales, birds, or seals eat or become entangled in plastic bags.
Sea turtles feed on jellyfish and often mistakenly eat plastic bags.

44. Summary
Municipal solid waste is managed by landfills, incineration, composting, waste reduction, and recycling.
The most fundamental way to reduce waste is to prevent it from ever becoming waste in the first place.
About 35% of the waste generated in North America is handled through recycling.
Future management of municipal solid waste will be an integrated approach involving landfills, incineration, composting, source reduction, and recycling.
The degree to which any option will be used depends on economics, changes in technology, and citizen awareness and involvement.