Ch. 21 Solid and Hazardous Waste

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Ch. 21 Solid and Hazardous Waste. APES Mrs. Soja. I.THE SOLID WASTE PROBLEM . A.Solid Waste - any unwanted material that is solid 1.The U.S. produces 11,000,000,000 tons per year (4.3 pounds per day) about 33% of the world’s total - PowerPoint PPT Presentation

Text of Ch. 21 Solid and Hazardous Waste

Ch. 21 Solid and Hazardous Waste

Ch. 21 Solid and Hazardous WasteAPES Mrs. Soja

I.THE SOLID WASTE PROBLEM

A.Solid Waste - any unwanted material that is solid1.The U.S. produces 11,000,000,000 tons per year (4.3 pounds per day) about 33% of the worlds total2.Waste Stream: the steady flow of wastes that humans produce from all sources

SOURCES OF SOLID WASTE

A.Mining waste 1.Makes up 75% of all waste, but much of that is used soil or spoil2. Mining wastes are left in large piles called slag heaps that can contaminate air and water.

Fig. 21.2, p. 519

Municipal1.5%Sewage sludge1%Mining and oiland gasproduction75%Industry9.5%Agriculture13%Fig. 21.3, p. 519

Burned in incinerators (16%)Dumped inlandfills (54%)Recycled orcomposted(30%)B. Industrial Solid Waste:

1. Scrap metal, plastics, paper, fly ash and sludge2. Most is burned or buried on-site

C. Municipal Solid Waste (MSW)1. From homes and businesses2. 700kg per person per year3. 60% dumped, 24% recycled, 16% burned

III.DISPOSAL OF SOLID WASTE

A.Open Dumps - Most common method in developing countries1.Manila: 10 huge dumpsThousands of people live and work on dumps scavenging for food & materials: Very unsafe 2.Cairo: Traditional garbage collectors live with their trash3.Outlawed in most developed countries, but still happensa.Dumping of materials like oil and paints: one liter can make 1,000,000 liters undrinkable

B.Sanitary Landfills

1.Stops problems with insects, rodents, cheap, low odor2.Litter is compacted and covered 6 every day3.Problems Associated with Sanitary Landfills a.New landfills (15%) are lined with plastic and clay to prevent leachate from getting into groundwater. Liners are only required in new landfills and only last for 30 years before they leak. Leachate is rainwater that gets contaminated as it moves through the landfill.b.60% of solid waste ends up in landfills, 50% of U.S. cities have used landfill spacec.Methane gas produced by decomposing microbes d. Cause traffic, noise and dust and deprive us of resources.

http://videos.howstuffworks.com/hsw/16921-the-garbage-story-an-introduction-video.htmFig. 21.12, p. 537

TopsoilSandClayGarbageGarbageSandSynthetic linerSandClaySubsoilWhen landfill is full,layers of soil and clayseal in trashMethane storageand compressorbuildingElectricitygeneratorbuildingLeachatetreatment systemMethane gasrecoveryPipe collect explosivemethane gas used as fuelto generate electricityCompactedsolid wasteLeachatestorage tanksLeachatemonitoringwellLeachatemonitoringwellGroundwaterGroundwaterGroundwatermonitoringwellGroundwatermonitoringwellLeachate pipesLeachate pipesLeachate pumped upto storage tanks forsafe disposalLeachate pumped upto storage tanks forsafe disposalClay and plastic liningto prevent leaks; pipescollect leachate frombottom of landfillFig. 21.13, p. 538

AdvantagesNo open burningLittle odorLow groundwaterpollution if sitedproperlyCan be builtquicklyLow operatingcostsCan handle largeamounts of waste

Filled land canbe used for otherpurposes

No shortage oflandfill space inmany areasDisadvantagesNoise and trafficDustAir pollution fromtoxic gases andvolatile organiccompoundsreleasegreenhousegases (methaneand CO2)

Groundwatercontamination

Slowdecompositionof wastes

Encourages waste production

Eventually leaksand cancontaminategroundwaterFig. 21.14, p. 538

AdvantagesSafe method ifsites are chosencarefully

Wastes can beretrieved ifproblemsdevelop

Low costDisadvantagesLeaks or spills atsurface

Leaks fromcorrosion of wellcasing

Existing fracturesor earth quakescan allow wastesto escape intogroundwater

Encourageswaste production

4. Energy from Landfills

a. Methane gas is produced by anaerobic microbes within the fill; can be harnessed for energyb. Still adds to global warming; risk of explosion from gases

The Special Problem of Tires in Landfillsa.Tires are made of vulcanized rubber that cannot be melted or reused

C.Incineration- also called energy recovery or Waste-to-Energy1.Trash is burned, and the heat is used to generate electricity2.1000 plants word-wide (110 in U.S.)3.Types of Incinerators

Fig. 21.11, p. 536

AdvantagesReduced trashvolume

Less need forlandfills

Low waterpollutionDisadvantagesHigh cost

Air pollution(especiallytoxic dioxins)

Produces ahighly toxic ash

Encourageswaste productionFig. 21.10, p. 536

Power plantSteamTurbineGeneratorElectricityCraneFurnaceBoilerWetscrubberElectrostaticprecipitatorConveyorWaterBottomashConven-tionallandfillWastetreatmentHazardousWastelandfillDirtywaterWaste pitSmokestackFlyasha.Mass Burn1)All trash burned2)More air pollution: 10-20% of original mass is ash: disposed of as toxic waste3) In the US- there are few regulations, regulations are not enforced and workers are untrained. b.Refuse-Derived 1)Trash is sorted before burning2)Less air pollution, higher quality fuel

4.Problems Associated with Incineration A. Carbon Monoxide, particulates, heavy metals and toxic chemicals releasedB. Expensive pollution control devices must be installed; scrubbers, electrostatic precipitatorsC. Electrostatic precipitators spray gases from incinerator giving them a positive charge and gases stick to negatively charged platesD.Ash produced must be disposed of in hazardous landfills

D. Composting

1.Organic Wastes a. Grass clipping, leaves and other organic wastes can be used as fertilizers

E. Ocean Dumping

1. 55,000,000 lbs of trash are dumped in the sea every year2. 300,000 lbs of fishing gear (causes 50,000 Northern Fur Seals to die every year)3. Ocean dumping prohibited in U.S. between 1988-1992Boats dump raw sewage overboard worldwide, and much of our solid waste ends up in the Ocean

F.Exporting Waste

1.Wastes get exported from developed to developing countriesa. Little control by receiving countries about what is in trash2.1994: ban on transporting toxic wastes3.Also happens within countries - trash goes to poor neighborhoods (Native American reservations)4.N.I.MB.Y. philosophy everywhere

WASTE PREVENTION (Reduce, Reuse & Recycle)

A. Integrated Waste Management1.Variety of methods to minimize waste (3 Rs= Reduce, Reuse, Recycle) 2. Saves money, decreases pollution control, reduces extraction of resources.