Waste Disposal Chapter 15

Solid Wastes Major source of solid waste in U.S. are: Major source of solid waste in U.S. are: –Agriculture (crops and animals): more than 50% –Mineral industry (spoils, tailings, slag, and other rock and mineral wastes) –Municipalities (small amount of municipal waste) –Industry (highly toxic)

Figure 15.1

Figure 15.2

Municipal Waste Disposal Open Dumps – unsightly, unsanitary, and smelly Open Dumps – unsightly, unsanitary, and smelly Sanitary Landfills – alternate layers of compacted trash and a covering material Sanitary Landfills – alternate layers of compacted trash and a covering material –In U.S. open dumps no longer tolerated –Landfill design is important –Barriers need to lock in toxins and chemicals; must reduce leakage into the environment –Important to control the migration of leachate out of the landfill Sites for sanitary landfills often controversial Sites for sanitary landfills often controversial –NIMBY, NIMFY, NIMEY, and NOPE laws apply

Figure 15.3

Fig Sanitary landfills

Fig landfill and Leachate

Fig “bathtub effect”

Figure 15.7 Remaining landfill capacity

Incineration Partial solution to space problems faced by landfills Partial solution to space problems faced by landfills Burning waste produces abundant carbon dioxide plus other toxic substances Burning waste produces abundant carbon dioxide plus other toxic substances Recent technology have improved incinerators to burn hotter that breakdown complex toxic substances to less dangerous ones Recent technology have improved incinerators to burn hotter that breakdown complex toxic substances to less dangerous ones Expensive to operate and still produce a residual waste; often toxic and require proper storage Expensive to operate and still produce a residual waste; often toxic and require proper storage The considerable heat generated by an incinerator can be recovered and used The considerable heat generated by an incinerator can be recovered and used

Figure 15.8 Proportions of municipal waste

Figure 15.9 Waste-to-energy incineration facility

Ocean Dumping Ship board incineration, over the open ocean, and dumping residual waste into the ocean Ship board incineration, over the open ocean, and dumping residual waste into the ocean –Similar to land-based incineration but at sea –Incineration not 100% effective, residual toxic materials and chemicals dumped into the ocean will still pollute the ocean Ocean dumping without incineration still popular in many places around the world Ocean dumping without incineration still popular in many places around the world –Very disastrous to local oceans where practiced A dumping site for one very high-volume waste product: dredge spoils A dumping site for one very high-volume waste product: dredge spoils

Figure Dumping sediments with pollutants

Reduce Waste Volume Less volume means less landfill space and slower filling of available sites Less volume means less landfill space and slower filling of available sites Handling (Nontoxic) Organic Matter Handling (Nontoxic) Organic Matter –Treated nontoxic organic waste can be fed to swine or composted Recycling – any reuse of waste reduces volume at landfills Recycling – any reuse of waste reduces volume at landfills –Recover recyclable waste by source separation; separate waste into useful categories (wood, paper, plastics, various metals, …) at the user’s site –Deposits on reusable material (glass, cans, containers, …) often attractive incentive –Many applications to this idea yet unexplored

Figures Solid wastes and paper recycle

Figure Recycling Symbols

Figures Recycling

Reduce Waste Volume Another options Another options Recycle crushed pavement as new roadbed materialRecycle crushed pavement as new roadbed material Recycle steel into other useful objectsRecycle steel into other useful objects Re-use bricks as footpathsRe-use bricks as footpaths Innovation has no limit hereInnovation has no limit here

Figure Municipal waste disposal

Figure Main generators of hazardous wastes

Liquid-Waste Disposal Sewage and by-products of industrial processes Sewage and by-products of industrial processes Strategies: Strategies: –Dilute and disperse –Concentrate and contain Neither strategy is safe in long term Neither strategy is safe in long term Secure Landfills – is it possible? Secure Landfills – is it possible? –Placing liquid-waste into sealed drums, and covering with impermeable lining material; idea is to assure that the leachate will not migrate Deep wells – inject deep into the crust Deep wells – inject deep into the crust –Leachate not contained –May act to lubricate faults –Expensive and unsafe

Fig Careless toxic-waste disposal leads to pollution

Figure A secure landfill design for toxic-waste disposal

Fig Deep-well disposal for liquid wastes

Other Strategies Incineration – produces carbon dioxide Incineration – produces carbon dioxide Treatment by chemicals to breakdown or neutralized liquid waste is a possibility Treatment by chemicals to breakdown or neutralized liquid waste is a possibility –Generate a less toxic liquid or residue –Would still require proper storage

Sewage Treatment Septic Systems: individual user-level treatment Septic Systems: individual user-level treatment –Settling tank: solids separated and bacterial breakdown begins –Leach field or absorption field: liquid with remaining dissolved organic matter seeps out of porous pipes –Soil microorganisms and oxygen complete the breakdown of the organic matter –Soil permeability and field size are controlling factors

Figure Septic tank system

Sewage Treatment Municipal Sewage Treatment Municipal Sewage Treatment –Primary treatment: removal of solids from organic liquid waste –Secondary treatment: bacteria and fungi act to dissolve and breakdown the organic matter –Tertiary or advanced treatment: filtration, chlorination, and other chemical treatment may occur

Figure Primary, secondary, and tertiary stages of municipal treatment

Ghosts of Toxins Past: Superfund Disposal of identifiable toxic wastes in U.S. is currently controlled Disposal of identifiable toxic wastes in U.S. is currently controlled Congress has mandated and provided billions of dollars to control and clean-up toxic spills from the past Congress has mandated and provided billions of dollars to control and clean-up toxic spills from the past –Expensive –Political dynamite

Figure The first 951 toxic-waste dump sites Figure Completed removals of Superfund,

Radioactive Wastes Radioactive Decay – unstable nuclei decay and produce energy Radioactive Decay – unstable nuclei decay and produce energy Radioisotopes each have their own rate of decay measured in a half-life Radioisotopes each have their own rate of decay measured in a half-life Half-lives of different radioisotopes vary from microseconds to billions of years Half-lives of different radioisotopes vary from microseconds to billions of years The decay of a radioisotope can not be accelerated or delayed The decay of a radioisotope can not be accelerated or delayed Energetic radioisotopes must be contained out of the environment for ‘ever’ Energetic radioisotopes must be contained out of the environment for ‘ever’

Figure 15.27

Figure 15.25

Table 15.2

Figure 15.26

Effects of Radiation Alpha, beta, and gamma rays are types of ionized radiation given off by the decay of various radioisotopes Alpha, beta, and gamma rays are types of ionized radiation given off by the decay of various radioisotopes Cancer, tumors, tissue burns, and genetic mutation can result due to exposure of high doses of radiation Cancer, tumors, tissue burns, and genetic mutation can result due to exposure of high doses of radiation Large doses result in death Large doses result in death Accidents have occurred: Accidents have occurred: –Chernobyl and Three Mile Island

Nature of Radioactive Wastes Radioisotopes with half-lives of a few years to hundreds of years present the most risk Radioisotopes with half-lives of a few years to hundreds of years present the most risk –Radioactive enough to cause harm –Persistent in the environment long enough to require management –Some are toxic chemical poisons Levels of radioactive waste: Levels of radioactive waste: –Low-level: do not require extraordinary disposal precautions –High-level: require extraordinary precautions; must be isolated from the biosphere with confidence for a long time

Historical Suggestions for Storage Space Space Antarctic Ice Antarctic Ice Plate Tectonic Subduction Zones Plate Tectonic Subduction Zones Seabed Disposal Seabed Disposal Bedrock Caverns for Liquid Waste Bedrock Caverns for Liquid Waste Bedrock Disposal of Solid High-Level Wastes Bedrock Disposal of Solid High-Level Wastes –Multiple barrier concept

Figure 15.28

Waste Isolation Pilot Plant (WIPP) Southeast New Mexico site for storage of transuranic wastes Southeast New Mexico site for storage of transuranic wastes –Opened March 26, 1999 WIPP is located in bedded salt underlain by evaporites and overlain by mudstone WIPP is located in bedded salt underlain by evaporites and overlain by mudstone –Located 2150 feet below the surface in a dry and stable tectonic region –Tectonic stable for over 200 million years

Figure a

Figure b

Figure 15.30

Yucca Mountain Established by Nuclear Waste Policy Act of 1982 – establish a high-level disposal site in the west Established by Nuclear Waste Policy Act of 1982 – establish a high-level disposal site in the west Yucca Mountain Attractive Characteristics: Yucca Mountain Attractive Characteristics: –Tuff host rock –Arid climate –Low population density –Low regional water table –Apparent geologic stability Geological studies were detailed and revealing Geological studies were detailed and revealing

Figure a

Figure b

Figure 15.32