Ch. 21 Solid and Hazardous Waste

1. Ch. 21 Solid and Hazardous Waste APES – Mrs. Soja – Part 1

2. 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 • 2. Waste Stream: the steady flow of wastes that humans produce from all sources

3. SOURCES OF SOLID WASTE A. Mining waste 1. Makes up 75% of all waste, but much of that is used soil or spoil 2. Mining wastes are left in large piles called slag heaps that can contaminate air and water.

4. Sewage sludge 1% Mining and oil and gas production 75% Municipal 1.5% Industry 9.5% Agriculture 13% Fig. 21.2, p. 519

5. Dumped in landfills (54%) Burned in incinerators (16%) Recycled or composted (30%) Fig. 21.3, p. 519

6. B. Industrial Solid Waste: 1. Scrap metal, plastics, paper, fly ash and sludge 2. Most is burned or buried on-site

7. C. Municipal Solid Waste (MSW) 1. From homes and businesses 2. 700kg per person per year 3. 60% dumped, 24% recycled, 16% burned

8. III. DISPOSAL OF SOLID WASTE • A. Open Dumps - Most common method in • developing countries • 1. Manila: 10 huge dumps • Thousands of people live and work on dumps • scavenging for food & materials: Very unsafe • 2. Cairo: Traditional garbage collectors live with • their trash • 3. Outlawed in most developed countries, but still • happens • a. Dumping of materials like oil and paints: one liter can make 1,000,000 liters undrinkable

9. B. Sanitary Landfills 1. Stops problems with insects, rodents, cheap, low odor 2. Litter is compacted and covered 6” every day 3. 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 space • c. 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.htm

10. Leachate monitoring well Leachate monitoring well Leachate pumped up to storage tanks for safe disposal Leachate pumped up to storage tanks for safe disposal Groundwater monitoring well Groundwater monitoring well Groundwater Leachate pipes Groundwater Leachate pipes When landfill is full, layers of soil and clay seal in trash Electricity generator building Methane storage and compressor building Topsoil Leachate treatment system Sand Clay Garbage Pipe collect explosive methane gas used as fuel to generate electricity Methane gas recovery Leachate storage tanks Compacted solid waste Garbage Sand Synthetic liner Clay and plastic lining to prevent leaks; pipes collect leachate from bottom of landfill Sand Clay Fig. 21.12, p. 537 Subsoil

11. Advantages Disadvantages Noise and traffic Dust Air pollution from toxic gases and volatile organic compounds release greenhouse gases (methane and CO2) Groundwater contamination Slow decomposition of wastes Encourages waste production Eventually leaks and can contaminate groundwater No open burning Little odor Low groundwater pollution if sited properly Can be built quickly Low operating costs Can handle large amounts of waste Filled land can be used for other purposes No shortage of landfill space in many areas Fig. 21.13, p. 538

12. Advantages Disadvantages Safe method if sites are chosen carefully Wastes can be retrieved if problems develop Low cost Leaks or spills at surface Leaks from corrosion of well casing Existing fractures or earth quakes can allow wastes to escape into groundwater Encourages waste production Fig. 21.14, p. 538

13. 4. Energy from Landfills a. Methane gas is produced by anaerobic microbes within the fill; can be harnessed for energy b. Still adds to global warming; risk of explosion from gases

14. The Special Problem of Tires in Landfills • a. Tires are made of vulcanized rubber that cannot be melted or reused

15. C. Incineration • - also called “energy recovery” or “Waste-to-Energy” • 1. Trash is burned, and the heat is used to generate electricity • 2. 1000 plants word-wide (110 in U.S.) • 3. Types of Incinerators

17. Advantages Disadvantages Reduced trash volume Less need for landfills Low water pollution High cost Air pollution (especially toxic dioxins) Produces a highly toxic ash Encourages waste production Fig. 21.11, p. 536

18. Power plant Steam Smokestack Electricity Turbine Generator Crane Wet scrubber Boiler Electrostatic precipitator Furnace Conveyor Dirty water Fly ash Water Bottom ash Waste pit Conven- tional landfill Hazardous Waste landfill Waste treatment Fig. 21.10, p. 536

19. a. Mass Burn • 1) All trash burned • 2) More air pollution: 10-20% of original mass is ash: disposed of as toxic waste • 3) In the US- there are few regulations, regulations are not enforced and workers are untrained. b. Refuse-Derived • 1) Trash is sorted before burning • 2) Less air pollution, higher quality fuel