1 Environmental Science A Study of Interrelationships Tenth Edition Enger Smith Chapter 18 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2 Solid Waste Management and Disposal Chapter 18

3 Outline Kinds of Solid Waste Municipal Solid Waste Waste Disposal Methods – Landfills – Incineration – Producing Mulch and Compost – Source Reduction – Recycling

4 Kinds of Solid Waste Solid Waste is generally made of objects or particles that accumulate on the site where they are produced. – Typically categorized by the sector of the economy responsible for producing them.

5 Kinds of Solid Waste Mining Wastes – Waste Material Left on Surface – Milling Tailings – Waste or Tailings Drainage 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.

6 Kinds of Solid Waste Industrial Solid Waste - Solid waste other than mining. – Estimated million tons annually.  Demolition Waste  Sludge  Combustion Ash Municipal Solid Waste – All the materials people in a region no longer want.  230 million tons annually.

7 Municipal Solid Waste In modern society, many products are discarded when they are broken or worn out, while others only have a temporary use. – Those that have only temporary uses make up the majority of solid waste.

8 Municipal Solid Waste Unites States produces about 230 million tons of municipal solid waste annually. – Equates to 2 kg of trash person / day.  Per capita waste has increased 70% since 1960.

9 Municipal Solid Waste Generation Rates

10 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.  Traditional Methods (dumping and burning) are no longer accepted.

11 Waste Generation and Lifestyle

12 Methods of Waste Disposal Landfills – Municipal solid waste landfill typically a depression in impermeable clay layer, lined with impermeable membrane.  Each day’s deposit of fresh garbage is covered with a layer of soil to prevent it from blowing around and to discourage animal scavengers.  Traditionally been primary method of waste disposal.  Cheap and Convenient

13 Landfills New landfills have complex bottom layers to trap contaminant-laden leachate. – Monitoring systems are necessary to detect methane gas production and groundwater contamination.  In some cases, methane collected and used to generate electricity. Currently cost up to $1 million per hectare to prepare.

14 Modern Landfill

15 Landfills Number of landfills is declining. – Many small landfills not meeting regulations. – Capacity has been reached. New landfills often resisted due to public concerns over groundwater contamination, odors, and truck traffic. – Politicians are often unwilling to take strong positions that might alienate constituents.

16 Reducing the Number of Landfills

17 Incineration Currently, about 15% of U.S. municipal solid waste is incinerated. – Production of electricity partially offsets disposal costs.  Most incinerators burn unprocessed municipal solid waste.  Mass Burn

18 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.

19 Incineration Even with modern pollution controls, small amounts of pollutants still released into environment. – Cost of land and construction for new incinerators are also major concerns facing many communities.  Construction costs in North America in 2000 ranged from $45 - $350 million.

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

21 Producing Mulch and Compost Mulch is organic material used to protect areas where the soil is disturbed, or to control growth of unwanted vegetation. – Organic material chopped or shredded into smaller pieces.

22 Producing Mulch and Compost Composting is using natural decomposition to transform organic material into compost (humus-like product). – With proper management of air and water, composting can transform large quantities over a short period of time. About 3,800 composting facilities currently in use in the United States.

23 Diverting Waste Through Composting

24 Producing Mulch and Compost Most municipal programs involve one of three composting methods: – Windrow Systems – Aerated Piles – Enclosed Vessels

25 Source Reduction 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.

26 Source Reduction Design Changes – Since 2-liter soft drink bottle introduced in 1977, weight has been reduced by 25%. Manufacturing Processes – Reduce waste, increase efficiency. Purchasing Decisions – Choose reduced packaging and plan quantities accordingly.

27 Source Reduction Using Materials to Avoid Waste Generation – Reduce use of hazardous materials. Reusing Items – Delay or prevent entry of items into waste collection stream.

28 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, reduces the:  Cost of waste disposal.  Amount of raw materials needed.  Amount of pollution generated.

29 Recycling In the United States, recycling (including composting) diverted about 30% of solid waste stream from landfills and incinerators in – Benefits  Resource Conservation  Pollution Reduction  Energy Savings  Job Creation  Less Need for Landfills and Incinerators

30 Recycling

31 Recycling Programs Container Laws – Required deposit on all reusable beverage containers.  National bottle bill would reduce litter, save energy and money, create jobs, and help conserve natural resources. Mandatory Recycling Laws – Provide statutory incentive to recycle.

32 Recycling Programs Curbside Recycling – ,000 U.S. cities had curbside recycling programs.  Grown to 9,000 cities by  Cities with curbside recycling tend to have higher recycling rates than cities that lack such programs.

33 Recycling Concerns Plastics are recyclable, but technology differs from plastic to plastic. – Milk Container  High-Density Polyethylene (HDPE) – Egg Container  Polystyrene (PS) – Soft-Drink Bottle  Poly-Ethylene Terephthalate (PET)

34 Increasing Amounts of Plastic in Trash

35 Recycling Concerns Plastics industry is researching new technologies. Economics are of concern. – Unless demand for products keeps pace with growing supply, recycling programs will face an uncertain future.

36 Recycling Concerns Long-term success of recycling programs is tied to other economic incentives such as taxing issues, development of and demand for products manufactured from recycled materials. – Government subsidies artificially lowers cost of virgin materials compared to recycled materials.  Demand for recycled products must grow if recycling is to succeed on a large scale.

37 Recycling Composite Prices

38 Review Kinds of Solid Waste Municipal Solid Waste Waste Disposal Methods – Landfills – Incineration – Producing Mulch and Compost – Source Reduction – Recycling

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