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Solid and Hazardous Waste
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Core Case Study: Love Canal — There Is No “Away”
Between , Hooker Chemical sealed multiple chemical wastes into steel drums and dumped them into an old canal excavation (Love Canal). In 1953, the canal was filled and sold to Niagara Falls school board for $1. The company inserted a disclaimer denying liability for the wastes. In 1957, Hooker Chemical warned the school not to disturb the site because of the toxic waste. In 1959 an elementary school, playing fields and homes were built disrupting the clay cap covering the wastes. In 1976, residents complained of chemical smells and chemical burns from the site.
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Love Canal — There Is No “Away”
President Jimmy Carter declared Love Canal a federal disaster area. The area was abandoned in 1980 (left) Love Canal sparked creation of the Superfund law, which forced polluters to pay for cleaning up abandoned toxic waste dumps.
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Types of Solid Waste Municipal Hazardous Industrial E-waste
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WASTING RESOURCES Solid waste: any unwanted or discarded material we produce that is not a liquid or gas. Municipal solid waste (MSW): produce directly from homes. Industrial solid waste: produced indirectly by industries that supply people with goods and services. Hazardous (toxic) waste: threatens human health or the environment because it is toxic, chemically active, corrosive or flammable.
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LUST – Not what you think!
Leaking Underground Storage Tanks Hundreds of thousands of underground storage tanks have been installed in industrial nations They are used to store many potentially toxic substances Over time, steel tanks corrode and begin to leak, contaminating groundwater used for cooking, drinking, and bathing
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WASTING RESOURCES The United States produces about a third of the world’s solid waste and buries more than half of it in landfills. About 98.5% is industrial solid waste. The remaining 1.5% is MSW. About 55% of U.S. MSW is dumped into landfills, 30% is recycled or composted, and 15% is burned in incinerators.
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Electronic Waste: A Growing Problem
E-waste consists of toxic and hazardous waste such as PVC, lead, mercury, and cadmium. The U.S. produces almost half of the world's e-waste but only recycles about 10% of it.
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Problems with E-Waste
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Integrated Waste Management
Reuse Source reduction Recycling Composting Landfill Incineration
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Reducing Solid Waste Consume less
Redesign manufacturing processes and products to use less material and energy Redesign manufacturing processes and products to produce less waste and pollution Develop products that are easy to repair, reuse, remanufacture, compost, or recycle
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Reducing Solid Waste Continued
Shift from selling goods to selling or leasing the services they provide Eliminate or reduce unnecessary packaging Fee-per-bag waste collection system Cradle-to-grave responsibility laws
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REUSE Reusing products is an important way to reduce resource use, waste, and pollution in developed countries. Reusing can be hazardous in developing countries for poor who scavenge in open dumps. They can be exposed to toxins or infectious diseases.
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RECYCLING Composting biodegradable organic waste mimics nature by recycling plant nutrients to the soil. Recycling paper has a number of environmental (reduction in pollution and deforestation, less energy expenditure) and economic benefits and is easy to do.
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RECYCLING Reuse and recycling are hindered by prices of goods that do not reflect their harmful environmental impacts, too few government subsidies and tax breaks, and price fluctuations.
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BURNING AND BURYING SOLID WASTE
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.
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Burning Solid Waste
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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.
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How Pollutants Can Enter the Environment From Sanitary Landfills
Atmosphere – methane, ammonia, hydrogen sulfide, and natural gas Retention in soil – heavy metals – lead, chromium, and iron Groundwater – soluble materials (chloride, nitrates, and sulfates) pass through waste Surface runoff – pick up leachate and transport it
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How Pollutants Can Enter the Environment From Sanitary Landfills
Removal in plants – some plants growing in the dispersal area can selectively take up heavy metals and other toxins and pass it through the food chain Plant residue – plants left in the field contain toxic substances Stream flow – groundwater or surface runoff Wind – toxic materials transported to other areas
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Modern Sanitary Landfills Contain Multiple Barriers
Clay and plastic liners to limit movement of leachate Surface and subsurface drainage to collect leachate Systems to collect methane gas Groundwater monitoring
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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
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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).
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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 • Gasoline 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? • 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
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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.
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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.
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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.
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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.
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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.
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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
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Case Study: Lead Lead is especially harmful to children and is still used in leaded gasoline and household paints in about 100 countries.
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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
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AIR WINDS PRECIPITATION WINDS PRECIPITATION 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 Deposition Small fish BIOMAGNIFICATION IN FOOD CHAIN 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
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Making the Transition to a Low-Waste Society
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.
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