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Section 5 Section 6 Section 7 Section 8

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1 Section 5 Section 6 Section 7 Section 8
Ch 22 Waste Management Section 5 Section 6 Section 7 Section 8

Globally, MSW is burned in over 1,000 large waste-to-energy incinerators, which boil water to make steam for heating water, or space, or for production of electricity. Japan and a few European countries incinerate most of their MSW.

3 Burning Solid Waste PLAY VIDEO Waste-to-energy incinerator with pollution controls that burns mixed solid waste. Figure 22-10

4 Trade-Offs Incineration Advantages Disadvantages Expensive to build
Reduces trash volume Expensive to build Costs more than short-distance hauling to landfills Less need for landfills Low water pollution Difficult to site because of citizen opposition Concentrates hazardous substances into ash for burial or use as landfill cover Some air pollution Older or poorly managed facilities can release large amounts of air pollution Figure 22.11 Trade-offs: advantages and disadvantages of waste-to-energy incineration of solid waste. These trade-offs also apply to the incineration of hazardous waste. QUESTION: Which single advantage and which single disadvantage do you think are the most important? Output approach that encourages waste production Sale of energy reduces cost Modern controls reduce air pollution Can compete with recycling for burnable materials such as newspaper Some facilities recover and sell metals Fig , p. 531

5 Burying Solid Waste Most of the world’s MSW is buried in landfills that eventually are expected to leak toxic liquids into the soil and underlying aquifers. Open dumps: are fields or holes in the ground where garbage is deposited and sometimes covered with soil. Mostly used in developing countries. Sanitary landfills: solid wastes are spread out in thin layers, compacted and covered daily with a fresh layer of clay or plastic foam.

6 Pipes collect explosive methane as used as fuel
When landfill is full, layers of soil and clay seal in trash Topsoil Electricity generator building Sand Clay Methane storage and compressor building Leachate treatment system Garbage Probes to detect methane leaks Pipes collect explosive methane as used as fuel to generate electricity Methane gas recovery well Leachate storage tank Compacted solid waste Figure 22.12 Solutions: state-of-the-art sanitary landfill, which is designed to eliminate or minimize environmental problems that plague older landfills. Even these landfills are expected to leak eventually, passing both the effects of contamination and cleanup costs on to future generations. Since 1997, only modern sanitary landfills are allowed in the United States. As a result, many older and small landfills have been closed and replaced with larger local and regional modern landfills. Garbage Groundwater monitoring well Leachate pipes Leachate pumped up to storage tank for safe disposal Sand Synthetic liner Leachate monitoring well Sand Clay and plastic lining to prevent leaks; pipes collect leachate from bottom of landfill Groundwater Clay Subsoil Fig , p. 532

7 Trade-Offs Sanitary Landfills Advantages Disadvantages
Noise and traffic No open burning Dust Little odor Air pollution from toxic gases and volatile organic compounds Low groundwater pollution if sited properly Releases greenhouse gases (methane and CO2) unless they are collected Can be built quickly Low operating costs Groundwater contamination Figure 22.13 Trade-offs: advantages and disadvantages of using sanitary landfills to dispose of solid waste. QUESTION: Which single advantage and which single disadvantage do you think are the most important? Can handle large amounts of waste Slow decomposition of wastes Filled land can be used for other purposes Discourages recycling, reuse, and waste reduction No shortage of landfill space in many areas Eventually leaks and can contaminate groundwater Fig , p. 533

8 Case Study: What Should We Do with Used Tires?
We face a dilemma in deciding what to do with hundreds of millions of discarded tires. Figure 22-14

9 HAZARDOUS WASTE Hazardous waste: is any discarded solid or liquid material that is toxic, ignitable, corrosive, or reactive enough to explode or release toxic fumes. The two largest classes of hazardous wastes are organic compounds (e.g. pesticides, PCBs, dioxins) and toxic heavy metals (e.g. lead, mercury, arsenic).

10 What Harmful Chemicals Are in Your Home?
Cleaning Gardening • Disinfectants • Pesticides • Drain, toilet, and window cleaners • Weed killers • Ant and rodent killers • Spot removers • Septic tank cleaners • Flea powders Paint • Latex and oil-based paints • Paint thinners, solvents, and strippers Automotive • Stains, varnishes, and lacquers Figure 22.15 Science: harmful chemicals found in many U.S. homes. The U.S. Congress has exempted disposal of these materials from government regulation. QUESTION: Which of these chemicals are in your home? • Gasoline • Wood preservatives • Used motor oil • Antifreeze • Artist paints and inks • Battery acid General • Solvents • Dry-cell batteries (mercury and cadmium) • Brake and transmission fluid • Glues and cements • Rust inhibitor and rust remover Fig , p. 534

11 Hazardous Waste Regulations in the United States
Two major federal laws regulate the management and disposal of hazardous waste in the U.S.: Resource Conservation and Recovery Act (RCRA) Cradle-to-the-grave system to keep track waste. Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Commonly known as Superfund program.

12 Hazardous Waste Regulations in the United States
The Superfund law was designed to have polluters pay for cleaning up abandoned hazardous waste sites. Only 70% of the cleanup costs have come from the polluters, the rest comes from a trust fund financed until 1995 by taxes on chemical raw materials and oil.

13 How Would You Vote? To conduct an instant in-class survey using a classroom response system, access “JoinIn Clicker Content” from the PowerLecture main menu for Living in the Environment. Should the U.S. Congress reinstate the polluter-pays principle by using taxes from chemical, oil, mining, and smelting companies to reestablish a fund for cleaning up existing and new Superfund sites? a. No. All taxpayers, not certain industries, should pay for cleaning up sites polluted in the past. b. Yes. Funding for Superfund is needed and waste-generating industries rather than ordinary citizens should fund it.

We can produce less hazardous waste and recycle, reuse, detoxify, burn, and bury what we continue to produce. Figure 22-16

15 Convert to Less Hazardous or Nonhazardous Substances
Produce Less Waste Manipulate processes to eliminate or reduce production Recycle and reuse Convert to Less Hazardous or Nonhazardous Substances Chemical, physical, and biological treatment Ocean and atmospheric assimilation Land treatment Thermal treatment Incineration Figure 22.16 Integrated hazardous waste management: priorities suggested by prominent scientists for dealing with hazardous waste. To date, these priorities have not been followed in the United States and in most other countries. (Data from U.S. National Academy of Sciences) Put in Perpetual Storage Arid region unsaturated zone Waste piles Surface impoundments Salt formations Underground injection Landfill Fig , p. 536

16 Conversion to Less Hazardous Substances
Physical Methods: using charcoal or resins to separate out harmful chemicals. Chemical Methods: using chemical reactions that can convert hazardous chemicals to less harmful or harmless chemicals.

17 Conversion to Less Hazardous Substances
Biological Methods: Bioremediation: bacteria or enzymes help destroy toxic and hazardous waste or convert them to more benign substances. Phytoremediation: involves using natural or genetically engineered plants to absorb, filter and remove contaminants from polluted soil and water.

18 Radioactive contaminants Organic contaminants Inorganic
metal contaminants Poplar tree Brake fern Sunflower Willow tree Indian mustard Landfill Polluted groundwater in Oil spill Figure 22.17 Solutions: phytoremediation. Various types of plants can be used as pollution sponges to clean up soil and water and radioactive substances (left), organic compounds (center), and toxic metals (right). (Data from American Society of Plant Physiologists, U.S. Environmental Protection Agency, and Edenspace) Polluted leachate Decontaminated water out Soil Soil Groundwater Groundwater Rhizofiltration Roots of plants such as sunflowers with dangling roots on ponds or in green- houses can absorb pollutants such as radioactive strontium-90 and cesium-137 and various organic chemicals. Phytostabilization Plants such as willow trees and poplars can absorb chemicals and keep them from reaching groundwater or nearby surface water. Phytodegradation Plants such as poplars can absorb toxic organic chemicals and break them down into less harmful compounds which they store or release slowly into the air. Phytoextraction Roots of plants such as Indian mustard and brake ferns can absorb toxic metals such as lead, arsenic, and others and store them in their leaves. Plants can then be recycled or harvested and incinerated.

19 Can reduce material dumped into landfills
Trade-Offs Phytoremediation Advantages Disadvantages Easy to establish Slow (can take several growing seasons) Inexpensive Effective only at depth plant roots can reach Can reduce material dumped into landfills Some toxic organic chemicals may evaporate from plant leaves Figure 22.18 Trade-offs: advantages and disadvantages of using phytoremediation to remove or detoxify hazardous waste. QUESTION: Which single advantage and which single disadvantage do you think are the most important? Produces little air pollution compared to incineration Some plants can become toxic to animals Low energy use Fig , p. 538

20 Conversion to Less Hazardous Substances
Incineration: heating many types of hazardous waste to high temperatures – up to 2000 °C – in an incinerator can break them down and convert them to less harmful or harmless chemicals.

21 Conversion to Less Hazardous Substances
Plasma Torch: passing electrical current through gas to generate an electric arc and very high temperatures can create plasma. The plasma process can be carried out in a torch which can decompose liquid or solid hazardous organic material.

22 Mobile. Easy to move to different sites
Trade-Offs Plasma Arc Advantages Disadvantages Small High cost Produces CO2 and CO Mobile. Easy to move to different sites Can release particulates and chlorine gas Figure 22.19 Trade-offs: advantages and disadvantages of using a plasma arc torch to detoxify hazardous wastes. QUESTION: Which single advantage and which single disadvantage do you think are the most important? Can vaporize and release toxic metals and radioactive elements Produces no toxic ash Fig , p. 538

23 Long-Term Storage of Hazardous Waste
Hazardous waste can be disposed of on or underneath the earth’s surface, but without proper design and care this can pollute the air and water. Deep-well disposal: liquid hazardous wastes are pumped under pressure into dry porous rock far beneath aquifers. Surface impoundments: excavated depressions such as ponds, pits, or lagoons into which liners are placed and liquid hazardous wastes are stored.

24 Deep Underground Wells
Trade-Offs Deep Underground Wells Advantages Disadvantages Safe method if sites are chosen carefully Leaks or spills at surface Leaks from corrosion of well casing Wastes can be retrieved if problems develop Existing fractures or earthquakes can allow wastes to escape into groundwater Figure 22.20 Trade-offs: advantages and disadvantages of injecting liquid hazardous wastes into deep underground wells. QUESTION: Which single advantage and which single disadvantage do you think are the most important? Easy to do Encourages waste production Low cost Fig , p. 539

25 Low construction costs
Trade-Offs Surface Impoundments Advantages Disadvantages Groundwater contamination from leaking liners (or no lining) Low construction costs Low operating costs Air pollution from volatile organic compounds Can be built quickly Overflow from flooding Figure 22.21 Trade-offs: advantages and disadvantages of storing liquid hazardous wastes in surface impoundments. QUESTION: Which single advantage and which single disadvantage do you think are the most important? Wastes can be retrieved if necessary Disruption and leakage from earthquakes Can store wastes indefinitely with secure double liners Promotes waste production Fig , p. 539

26 Long-Term Storage of Hazardous Waste
Long-Term Retrievable Storage: Some highly toxic materials cannot be detoxified or destroyed. Metal drums are used to stored them in areas that can be inspected and retrieved. Secure Landfills: Sometimes hazardous waste are put into drums and buried in carefully designed and monitored sites.

27 Secure Hazardous Waste Landfill
In the U.S. there are only 23 commercial hazardous waste landfills. Figure 22-22

28 Bulk waste Gas vent Topsoil Plastic cover Earth Impervious clay cap
Sand Clay cap Impervious clay Water table Figure 22.22 Solutions: secure hazardous waste landfill. Earth Leak detection system Groundwater Plastic double liner Double leachate collection system Reactive wastes in drums Groundwater monitoring well Fig , p. 540

29 • Use pesticides in the smallest amount possible.
What Can You Do? Hazardous Waste • Use pesticides in the smallest amount possible. • Use less harmful substances instead of commercial chemicals for most household cleaners. For example use liquid ammonia to clean appliances and windows; vinegar to polish metals, clean surfaces, and remove stains and mildew; baking soda to clean household utensils, deodorize, and remove stains; borax to remove stains and mildew. Figure 22.23 Individuals matter: ways to reduce your input of hazardous waste into the environment. QUESTION: Which two things in this list do you do or plan to do? • Do not dispose of pesticides, paints, solvents, oil, antifreeze, or other products containing hazardous chemicals by flushing them down the toilet, pouring them down the drain, burying them, throwing them into the garbage, or dumping them down storm drains. Fig , p. 540

30 Case Study: Lead Lead is especially harmful to children and is still used in leaded gasoline and household paints in about 100 countries. Figure 22-24

31 Solutions Lead Poisoning Prevention Control
Phase out leaded gasoline worldwide Sharply reduce lead emissions from old and new incinerators Phase out waste incineration Replace lead pipes and plumbing fixtures containing lead solder Test blood for lead by age 1 Remove leaded paint and lead dust from older houses and apartments Ban use of lead solder Remove lead from TV sets and computer monitors before incineration or land disposal Ban use of lead in computer and TV monitors Figure 22.24 Solutions: ways to help protect children from lead poisoning. QUESTION: Which two of these solutions do you think are the most important? Test for lead in existing ceramicware used to serve food Ban lead glazing for ceramicware used to serve food Test existing candles for lead Ban candles with lead cores Wash fresh fruits and vegetables Fig , p. 541

32 Case Study: Mercury Mercury is released into the environment mostly by burning coal and incinerating wastes and can build to high levels in some types of fish. Figure 22-26

33 Solutions Mercury Pollution Prevention Control  
Phase out waste incineration Sharply reduce mercury emissions from coal-burning plants and incinerators Remove mercury from coal before it is burned Convert coal to liquid or gaseous fuel Tax each unit of mercury emitted by coal-burning plants and incinerators Switch from coal to natural gas and renewable energy resources such as wind, solar cells, and hydrogen Collect and recycle mercury-containing electric switches, relays, and dry-cell batteries Figure 22.26 Solutions: ways to prevent or control inputs of mercury into the environment from human activities—mostly through coal-burning plants and incinerators. QUESTION: Which four of these solutions do you believe are the most important? Phase out use of mercury in all products unless they are recycled Require labels on all products containing mercury Fig , p. 543

Hg and SO2 Hg2+ and acids Hg2+ and acids Photo- chemical Human sources Elemental mercury vapor (Hg) Inorganic mercury and acids (Hg2+) Inorganic mercury and acids (Hg2+) Coal- burning plant Incinerator Deposition Runoff of Hg2+ and acids Deposition WATER Large fish Vaporization Deposition Small fish BIOMAGNIFICATION IN FOOD CHAIN Deposition Figure 22.25 Science: cycling of mercury in aquatic environments, in which mercury is converted from one form to another. The most toxic form to humans is methylmercury (CH3Hg+), which can be biologically magnified in aquatic food chains. Some mercury is also released back into the atmosphere as mercury vapor. QUESTION: What is your most likely exposure to mercury? Phytoplankton Zooplankton Bacteria and acids Oxidation Elemental mercury liquid (Hg) Inorganic mercury (Hg2+) Organic mercury (CH3Hg+) Bacteria Settles out Settles out Settles out SEDIMENT Fig , p. 542

In the U.S., citizens have kept large numbers of incinerators, landfills, and hazardous waste treatment plants from being built in their local areas. Environmental justice means that everyone is entitled to protection from environmental hazards without discrimination.

36 Global Outlook: International Action to Reduce Hazardous Waste
An international treaty calls for phasing out the use of harmful persistent organic pollutants (POPs). POPs are insoluble in water and soluble in fat. Nearly every person on earth has detectable levels of POPs in their blood. The U.S has not ratified this treaty.

37 Making the Transition to a Low-Waste Society: A New Vision
Everything is connected. There is no “away” for the wastes we produce. Dilution is not always the solution to pollution. The best and cheapest way to deal with wastes are reduction and pollution prevention.

38 Animation: Economic Types

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