Solid Waste Objective: I will define solid waste and explain how most municipal solid waste is disposed of.
WASTING RESOURCES Ø Solid waste: any unwanted or discarded material we produce that is not a liquid or gas. l l Municipal solid waste (MSW): produce directly from homes. Industrial solid waste: produced indirectly by industries that supply people with goods and services. Ø Hazardous (toxic) waste: threatens human health or the environment because it is toxic, chemically active, corrosive or flammable.
WASTING RESOURCES Ø The United States produces about a third of the world’s solid waste and buries more than half of it in landfills. l l 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. • The average American produces about 4 lbs of trash every day.
Electronic Waste: A Growing Problem Ø E-waste consists of toxic and hazardous waste such as PVC, lead, mercury, and cadmium. Ø The U. S. produces almost half of the world's e-waste but only recycles about 10% of it. Figure 22 -4
Integrated Waste Management Ø We can manage the solid wastes we produce and reduce or prevent their production. l l l First Priority: reduce harmful chemical use, use less packaging, make products last longer Second Priority: reuse, repair, recycle, compost Third Priority: incinerate waste, bury waste, release waste into environment
Solutions: The 5 R’s Ø Refuse: to buy items that we really don’t need. Ø Reduce: consume less and live a simpler and less stressful life by practicing simplicity. Ø Reuse: rely more on items that can be used over and over. Ø Repurpose: use something for another purpose instead of throwing it away. Ø Recycle: paper, glass, cans, plastics…and buy items made from recycled materials.
Solutions: What can YOU do? Ø Ø Ø Ask yourself whether you really need a particular item. Rent or borrow goods and services. Do not use throwaway paper and plastic plates, etc. when reusable or refillable versions are available. Refill and reuse a bottled water container with tap water. Use e-mail in place of conventional paper mail. Read newspapers and magazines online.
REUSE Ø 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.
Case Study: Using Refillable Containers Ø Refilling and reusing containers uses fewer resources and less energy, produces less waste, saves money, and creates jobs. l l In Denmark and Canada’s Price Edward’s Island there is a ban on all beverage containers that cannot be reused. In Finland 95% of soft drink and alcoholic beverages are refillable (Germany 75%).
Solutions: Other Ways to Reuse Things Ø We can use reusable shopping bags, food containers, and shipping pallets, and borrow tools from tool libraries. l Many countries in Europe and Asia charge shoppers for plastic bags.
Think Box Ø Should consumers have to pay for plastic or paper bags at grocery and other stores? l l a. No. Instead, give discounts to people who bring their own bags. b. Yes. Making consumers buy their bags will reduce waste.
Solutions: What can YOU do? Ø Use reusable lunch bags or boxes Ø Use rechargable batteries Ø Store food in reusable containers instead of plastic bags or foil Ø Buy used furniture, cars, computers, etc. Ø Give or sell items you no longer use
RECYCLING Ø Primary (closed loop) recycling: materials are turned into new products of the same type. Ø Secondary recycling: materials are converted into different products. l l Used tires shredded and converted into rubberized road surface. Newspapers transformed into cellulose insulation.
RECYCLING Ø There is a disagreement over whether to mix urban wastes and send them to centralized resource recovery plants or to sort recyclables for collection and sale to manufacturers as raw materials. l To promote separation of wastes, 4, 000 communities in the U. S. have implemented payas-you-throw or fee-per-bag waste collection systems.
RECYCLING Ø Composting biodegradable organic waste mimics nature by recycling plant nutrients to the soil. Ø Recycling paper has a number of environmental (reduction in pollution and deforestation, less energy expenditure) and economic benefits and is easy to do.
RECYCLING Ø Recycling many plastics is chemically and economically difficult. l l Many plastics are hard to isolate from other wastes. Recovering individual plastic resins does not yield much material. The cost of virgin plastic resins in low than recycled resins due to low fossil fuel costs. There are new technologies that are making plastics biodegradable.
RECYCLING Ø 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.
Trade-Offs Recycling Advantages Disadvantages Reduces air and water pollution Does not save landfill space in areas with ample land Saves energy Reduces mineral demand Reduces greenhouse gas emissions Reduces solid waste production and disposal May lose money for items such as glass and most plastic Helps protect biodiversity Reduces profits from landfills and incinerators Can save money for items such as paper, metals, and some plastics Source separation is inconvenient for some people Important part of economy Fig. 22 -9, p. 529
BURNING AND BURYING SOLID WASTE Ø 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. l Japan and a few European countries incinerate most of their MSW.
Burning Solid Waste Ø Waste-to-energy incinerator with pollution controls that burns mixed solid waste. Figure 22 -10
Trade-Offs Incineration Advantages Reduces trash volume Less need for landfills Disadvantages Expensive to build Costs more than short-distance hauling to landfills Low water pollution Difficult to site because of citizen opposition Concentrates hazardous substances into ash for burial or use as landfill cover Some air pollution Older or poorly managed facilities can release large amounts of air pollution Sale of energy reduces cost Output approach that encourages waste production Modern controls reduce air pollution Can compete with recycling for burnable materials such as newspaper Some facilities recover and sell metals Fig. 22 -11, p. 531
Case Study: What Should We Do with Used Tires? Ø We face a dilemma in deciding what to so with hundreds of millions of discarded tires. Figure 22 -14
Think Box Ø Do the advantages of incinerating solid waste outweigh the disadvantages? l l a. Yes. Incineration is a sanitary and effective method for eliminating infectious and organic wastes. b. No. Incineration can generate toxic air pollution and ashes.
Burying Solid Waste Ø Most of the world’s MSW is buried in landfills that eventually are expected to leak toxic liquids into the soil and underlying aquifers. l l 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.
Topsoil Sand Clay Garbage Probes to detect methane leaks When landfill is full, layers of soil and clay seal in trash Electricity Methane storage and compressor building Methane gas recovery well Synthetic liner Sand Clay Subsoil Leachate treatment system Pipes collect explosive methane as used as fuel to generate electricity Leachate storage tank Compacted solid waste Garbage Sand generator building Leachate pipes Leachate pumped up to storage tank for safe disposal Clay and plastic lining to prevent leaks; pipes collect leachate from bottom of landfill Groundwater monitoring well Leachate monitoring well Fig. 22 -12, p. 532
Trade-Offs Sanitary Landfills Advantages No open burning Little odor Low groundwater pollution if sited properly Can be built quickly Low operating costs Disadvantages Noise and traffic Dust Air pollution from toxic gases and volatile organic compounds Releases greenhouse gases (methane and CO 2) unless they are collected Groundwater contamination Can handle large amounts of waste Slow decomposition of wastes Filled land can be used for other purposes Discourages recycling, reuse, and waste reduction No shortage of landfill space in many areas Eventually leaks and can contaminate groundwater Fig. 22 -13, p. 533
Think Box Ø Do the advantages of burying solid waste in sanitary landfills outweigh the disadvantages? l l a. No. Ultimately, landfills leak and pollute the environment. b. Yes. They have relatively low operating costs, can store large amounts of waste, and are designed to prevent pollution.