1 / 41

Chapter 18: Hazardous Substances and Wastes

Chapter 18: Hazardous Substances and Wastes. 18.1 Hazardous and Toxic Materials in Our Environment 18.2 Characterizing Hazardous and Toxic Materials 18.3 Controlling Hazardous Materials and Waste 18.4 How Hazardous Wastes Enter the Environment 18.5 Hazardous-Waste Dumps —A Legacy of Abuse

damian
Télécharger la présentation

Chapter 18: Hazardous Substances and Wastes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 18: Hazardous Substances and Wastes • 18.1 Hazardous and Toxic Materials in Our Environment • 18.2 Characterizing Hazardous and Toxic Materials • 18.3 Controlling Hazardous Materials and Waste • 18.4 How Hazardous Wastes Enter the Environment • 18.5 Hazardous-Waste Dumps—A Legacy of Abuse • 18.6 Toxic Chemical Releases • 18.7 Hazardous-Waste Management Choices • 18.8 International Trade in Hazardous Wastes • 18.9 Nuclear Waste Disposal

  2. 18.1 Hazardous and Toxic Materials in Our Environment • Our modern technological society makes use of a large number of substances that are hazardous or toxic. • The benefits gained from using these materials must be weighted against the risks associated with their use. • At sites around the world, accidental or purposeful releases of hazardous and toxic chemicals are contaminating the land, air, and water. • Increasingly, governments and international agencies are attempting to control the growing problem.

  3. The life cycle of toxic substances

  4. 18.2 Characterizing Hazardous and Toxic Materials • Terms are incorrectly used interchangeably. • Toxic commonly refers to a narrow group of substances that are poisonous and cause human injury or death. • Hazardous is a broader term; it refers to all dangerous materials (including toxic ones) that create a human health or environmental problem. • Many hazardous and toxic materials are raw materials or finished products used by industry or the public (i.e. gasoline, pesticides, industrial chemicals, medicine). • Hazardous wastes are by-products of industrial, business, or household activities for which there is no immediate use. • They must be disposed of in an appropriate manner. • There are stringent regulations pertaining to production, storage, and disposal.

  5. Figure 18_02

  6. Identifying hazardous materials • Hazardous substances or hazardous materials are those that can cause harm to humans or the environment. • The EPA defines hazardous materials as having one or more of the following characteristics: • Ignitability (Fire hazard).. Gasoline, paint thinner, alcohol… • Corrosiveness (Corrodes material)… strong acids and bases… • Reactivity (Explosiveness)… gunpowder, metal sodium… • Toxicity (May release toxins)… mercury, lead… • Some hazardous materials, such as gasoline, fall into several categories.

  7. http://www.youtube.com/watch?v=-gdXIEW-WdE • http://www.youtube.com/watch?v=JYqH-cxX-ug • http://www.youtube.com/watch?v=GlEtQ2qlxEU

  8. 18.3 Controlling Hazardous Materials and Waste • To regulate the use of toxic and hazardous substances and the generation of toxic and hazardous wastes, most countries draw up a list of specific substances that have been scientifically linked to adverse human health or environmental effects. • The U.S. has attempted to deal with hazardous substances and wastes by using “command and control” methods of governmental regulations, beginning with the development of the EPA and OSHA in 1970. • Many states, as well as some countries, have tried to mirror these regulations by codifying their own statues specific to their needs. • State regulations can be equal or more stringent than federal regulations.

  9. Controlling Hazardous Materials and Waste • Most lists of toxic and hazardous substances include only known offenders, since many potentially harmful chemical compounds have yet to be tested adequately. • Governments and regulatory agencies must attempt to determine how to fairly enforce measures to successfully control exposures to humans and the environment. • Governments must assess who will pay for cleanup of hazardous substances or wastes that enter the environment.

  10. Managing health risks • Acute vs. Chronic Toxicity • Effects of massive doses at once (acute toxicity) and small doses over time (chronic toxicity) differ. • Chronic toxicity is much harder to detect as effects may not surface for long periods of time (lead in paints might affect nervous system). • Acute toxicity… consuming extremely high amounts of alcohol can result in death. • Synergism • Assessing the effects of chemical mixtures is also problematic. • Most toxicity studies focus on a single compound. • Synergism is the potential of relatively harmless individual compounds to become highly toxic and do great damage when combined (i.e. radioactive gases and tobacco smoke).

  11. Managing health risks • Persistent pollutants remain in the environment, essentially unchanged, for long periods. • Most are human-made. • Synthetic chemicals are part of our food, transportation, clothing, building materials, home appliances, medicine, recreational equipment, and many other items. • DDT is a persistent pollutant. • Nonpersistent pollutants do not remain for a long period and are often biodegradable. • Many toxic organic materials can be destroyed by decomposer organisms. • Organophosphates decompose in several weeks. • They do not accumulate in food chain.

  12. Managing health risks • Setting Exposure Limits • Nearly all substances are toxic in sufficiently high doses. • At what dose a chemical become a hazard? • Several government agencies test and set exposure limits in a variety of units: PEL (Permissible Exposure Limits), STEL (Short Term Exposure Limits), TWA (Time Weighted Average), CL (Ceiling Limit). • People can be exposed in three ways: • Inhalation, Consumption, Absorption • Typically the regulatory agency will determine the level of exposure at which none of the test animals is affected (threshold level) and then set the exposure level lower to allow for a safety margin. • Even when concentrations are set, they may vary considerably from country to country.

  13. 18.4 How Hazardous Wastes Enter the Environment • There are numerous types of hazardous wastes, taking many forms: • Heavy metals (mercury, cadmium, lead) • Organic wastes • Liquid, sludge, incinerator ash Industry and mining are the main sources of hazardous wastes, as well as hospitals, military establishments, transport services, and small workshops. • Improper handling and disposal can affect human health and the environment through contamination. • Effects of exposure can be immediate or long-term concerns.

  14. How Hazardous Wastes Enter the Environment • Hazardous wastes enter the environment in many ways: • Evaporation (solvents used in paints) • Fugitive emissions (escape from faulty piping and valves) • Improper disposal (leaking from landfills) • Improper labeling and record-keeping

  15. 18.5 Hazardous-Waste Dumps—A Legacy of Abuse • Prior to RCRA in 1976, hazardous waste was essentially unregulated. • Hazardous wastes were simply buried or dumped. • Sites were typically located convenient to the industry and were often in environmentally sensitive areas. • In North America alone, there are over 25,000 abandoned or uncontrolled sites. • U.S. Resource Conservation and Recovery Act of 1976 (RCRA): • This act created the “cradle-to-grave” concept of hazardous waste management by regulating generators, transporters, and Treatment Storage and Disposal Facilities (TSDF) as well as underground storage tanks (USTs) and petroleum products. • This act also defined toxic and/or hazardous waste by using the terms listed and characteristic waste.

  16. Hazardous-Waste Dumps—A Legacy of Abuse • Under RCRA, substances are considered toxic or hazardous if they: • Cause or significantly contribute to an increase in mortality or an increase in serious irreversible, or incapacitating reversible, illness; or pose a substantial present or potential hazard to human health or the environment when improperly treated, stored, transported, disposed of, or otherwise managed.

  17. Hazardous-Waste Dumps—A Legacy of Abuse • In the U.S., the federal government has become the principal participant in the cleanup of hazardous-waste sites. • The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) was enacted in 1980. • This program deals with financing the cleanup of large, uncontrolled hazardous-waste sites and has become known as Superfund.

  18. Hazardous-Waste Dumps—A Legacy of Abuse • CERCLA had several key objectives: • Develop a comprehensive program to set priorities for cleaning up the worst existing sites. • Make responsible parties pay for cleanup when possible. • Set up a $1.6 billion Hazardous Waste Trust Fund (Superfund) to support the identification and cleanup of abandoned hazardous-waste sites. • Advance scientific and technological capabilities in hazardous waste management, treatment, and disposal.

  19. Hazardous-Waste Dumps—A Legacy of Abuse • A National Priorities List was drawn up for Superfund action. • Under CERCLA, over 44,000 sites were evaluated, and about 11,000 were considered serious enough to warrant further investigation. • The number of sites on the National Priorities List fluctuates as new sites are added and old sites are deleted as they are cleaned up. • Currently there are about 1,200 sites on the National Priorities List.

  20. Hazardous-Waste Dumps—A Legacy of Abuse • Because any contributor to the site could be held responsible for entire cleanup costs, regardless of the degree to which they contributed to the problem, many companies found it cost-effective to hire lawyers to fight their inclusion in cleanup efforts. • About 1100 sites have been cleaned up. • Most of the remaining sites are in the process of being cleaned up or are under study about the best way to proceed. • $27 billion in total expenditures

  21. 18.6 Toxic Chemical Releases • After the Emergency Planning and Community Right-to-Know Act (EPCRA) was passed in 1986, any industrial plant that released at least 23,000 kg of toxic pollutants into the environment was required to file a report. • These were primarily manufacturing industries. • The information collected allowed EPA to target specific industries for enforcement action. • About 1.5 billion kg of toxic chemicals were reported released into the environment by industry in 2009. • Primary industries involved are mining, power generation, chemical, and metal manufacturing.

  22. 18.6 Toxic Chemical Releases Sources of toxic releases

  23. 18.7 Hazardous-Waste Management Choices • The EPA promotes a pollution prevention hierarchy (P2): • Reduce the amount of pollution at the source. • Recycle wastes whenever possible. • Treat wastes to reduce hazard and / or volume. • Dispose of wastes on land or incinerate them as last resort.

  24. Choices Pollution-prevention hierarchy

  25. Hazardous-Waste Management Choices • Pollution prevention (P2) encourages changes that prevent hazardous wastes from being produced. • Many of the actions are simple and cost little. • U.S. army phasing out lead bullets. • Waste minimization involves manufacturing changes that can reduce waste. • Replace hazardous solvents (use water instead).

  26. Hazardous-Waste Management Choices • Recycling wastes involves using wastes for another purpose, thus eliminating them as “waste.” • Burn waste oils and solvents as fuel. • Incorporate ash or other solid wastes into concrete or other building materials.

  27. Hazardous-Waste Management Choices • Wastes can be treated in a way that their amount is reduced or their hazardous nature is modified. • Neutralization of dangerous acids and bases by reacting them with one another. • Biodegradation of organic materials by the actions of microorganisms. • Air stripping to remove volatile chemicals from water. • Carbon absorption tanks contain specifically activated particles of carbon to treat hazardous chemicals in waste. • Precipitation involves adding special materials to a liquid waste to allow them to bind to hazardous chemicals and cause them to precipitate out of the liquid.

  28. Hazardous-Waste Management Choices • Despite recycling and treatment activities, some wastes still need to be disposed. • Currently, the two most common methods for disposing of hazardous wastes are incineration and land disposal. • Incineration (thermal treatment) burns wastes at high temperatures. A well-designed, well-run incinerator can destroy 99.9999% of hazardous materials. • High costs and concerns about emissions have kept incineration from becoming a major method in North America.

  29. Hazardous-Waste Management Choices • Land disposal is the primary method used when all other options have been exhausted. • Deep-well injection into porous geological formations. • Discharge of treated or untreated liquids into water sources • Placement of liquid wastes into surface holding areas (lagoons) • Storage of solid wastes in hazardous waste landfills. • Immobilizing a waste puts it into a solid form that is easier to handle, and is less likely to enter the surrounding area. • Fixation • Solidification

  30. 18.9 Nuclear Waste Disposal • Radioactive wastes are hazardous and toxic by the definition of the RCRA but are regulated in a different manner than other hazardous materials. • The U.S. Nuclear Regulatory Commission (NRC) and the Department of Energy (DOE) have responsibility for dealing with nuclear waste.

  31. Nuclear Waste Disposal • The DOE is responsible for nuclear research for both weapons and peaceful uses. • Historically, research and production dealt with hazardous chemicals and minor radioactive wastes by burying them, storing them in ponds, or releasing them into rivers. • The DOE has become steward of a large number of sites that are contaminated with hazardous chemicals and radioactive materials. • There were thousands of contaminated sites containing hundreds of underground storage tanks, millions of 55 gallon drums of waste, and thousands of sites with contaminated soils. • Several major sites have been cleaned up. • Each year there are fewer sites, and those remaining are smaller.

  32. Nuclear Waste Disposal • There are four general categories of nuclear wastes: • Transuranic wastes are highly radioactive waste that contain large numbers of atoms that are larger than uranium with half-lives greater than 20 years. • Uranium mining and milling wastes have low levels of radioactivity but are above background levels. • High-level radioactive wastes are spent fuel rods and highly radioactive materials from the reprocessing of fuel rods. • Low-level radioactive wastes have low levels of radioactivity and are not classified into one of the other categories.

  33. Nuclear Waste Disposal • Transuranic waste from former nuclear weapons sites is transported to the Waste Isolation Pilot Plant (WIPP) near Carlsbad, NM, which began accepting waste in March, 1999. • Waste management activities of mining and milling waste include: • Building fences. • Putting up warning signs. • Establishing land use restrictions. • Covering the wastes with a thick layer of soil and rock to prevent erosion, windblown particles, and groundwater contamination.

  34. DOE high-level radioactive transuranic waste sites

  35. Nuclear Waste Disposal • Disposal of high-level radioactive waste is a major problem for the nuclear power industry. • In the U.S., about 30,000 metric tons of highly radioactive spent fuel rods are stored in special storage ponds at nuclear reactor sites. • There is no permanent storage facility, and many plants are running out of temporary storage. • Most experts feel the best solution is to bury waste in a stable geologic formation.

  36. Nuclear Waste Disposal • The history of U.S. efforts to establish a repository for high-level radioactive waste is long and complicated. • 1982--U.S. Congress passed legislation for a high-level nuclear waste disposal site to be completed by 1998. • 1987--Several sites were considered and Yucca Mountain was selected for further study. • 1994-1997--A 5-mile U-shaped tunnel was constructed to study the suitability of the site. • 2002--Yucca Mountain was designated the nuclear repository. • 2008--Department of Energy filed a license application with the Nuclear Regulatory Commission to construct a repository for spent nuclear fuel and high level radioactive waste at Yucca Mountain. • 2010--President Obama withdraws funding for Yucca Mountain and the Department of Energy withdraws its request to the Nuclear Regulatory Commission to operate the facility.

  37. Aboveground storage of spent fuel rods

  38. Nuclear Waste Disposal • Currently, the U.S. produces about 57,000 cubic metersof low-level radioactive waste annually. • It is presently buried in disposal sites in South Carolina, Washington, and Utah. • 1986 was the deadline for each state providing it’s own storage sites. • Later states formed regional compacts where one state provided a disposal site. • Today many states do not have a permanent disposal site for low-level radioactive waste.

  39. Low-level radioactive waste sites

More Related