Chapter 16: Waste Generation and Disposal

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Karteikarten am Chapter 16: Waste Generation and Disposal, erstellt von sabrinapar22 am 19/02/2015.
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Zusammenfassung der Ressource

Frage Antworten
waste -outputs not useful or consumed, non useful products generated within the system
What are examples of inputs in human systems? raw materials, energy
What are examples of outputs in human systems? -waste energy, material that can be recycled or disposed of
What caused consumption patterns in the United States to change? -rapid population growth after WW II -increased industrialization -wealth -cultural changes
planned obsolescence the design of a product so that it will need to be replaced within a few years
municipal solid waste MSW refuse collected by municipalities from households, small businesses, institutions (schools, prisons), municipal buildings, and hospitals -60% MSW from residences -40% MSW from commercial and institutional facilities
What factors vary waste generation? -season of the year -socioeconomic status of the individual -geographic location
waste stream -flow of solid waste that is recycled, incinerated, placed in a solid landfill, or disposed of in another way
paper in solid waste stream -newsprint, office paper, cardboard, boxboard -31% of waste stream -231 million metric tons (254 million US tons) -decreased from 40%
organic materials in the solid waste stream -yard waste and food scraps 26% of MSW -wood 7% of MSW
plastic in solid waste stream -12% MSW
compostable goods -largely made up of organic material that can decompose under proper conditions
containers and packaging in solid waste stream 31% of MSW -intended for one use
food and yard waste in the solid waste stream -26% of MSW
non durable goods in the solid waste stream 25% MSW -newspapers, white paper, printed products, plastic items
durable goods in the solid waste stream -18% of MSW -appliances, tires, other manufactured products
E-waste in the waste stream -2% -televisions, computers, cell phones
How is e-waste dangerous to the environment? -contains heavy metals such as mercury, cadium -little infrastructure to recycle
reduce -optimal way to reduce solid waste generation -waste minimization or prevention -reduced input = reduced output
source reduction -reduction of wast by reducing the use of materials in the early stages of design and manufacture -increase energy efficiency -economic benefits -implemented on both individual or corporate levels
reuse -allows a material to cycle within a system longer before becoming an output
recycling -process by which are collected and converted into raw materials that are then used to produce new objects -rates increased in US since 1975 -US recycles 1/3 of MSW -requires more energy than reducing or reusing
closed loop recycling -recycling of a product into the same product -eg aluminum cans made into new aluminum cans
open loop recycling -one product is recycled into another product -eg plastic soda bottle is recycled into polar fleece jackets -does not reduce demand for raw material
What are the two problems of organic materials in landfills? -take up space -absence of oxygen causes material to decompose anaerobically and produce methane gas
compost organic matter that has decomposed under controlled conditions to produce an organic-rich material that enhances soil structure, cation exchange capacity, and fertility
What materials are compostable? vegetables, vegetable by-products such as cornstalks, grass, animal manure, yard wastes, and paper fiber
What is the process of composting? 1. detritivores break down dead tissues and waste products into smaller particles 2. decomposers complete the breakdown process by recycling nutrients from dead tissues and wastes back into the ecosystem 3. frequent turning for aerobic decomposition
What carbon to nitrogen ration best supports rapid decomposition? 30:1 -layers of brown material and green material
How do large scale composting facilities operate? 1. waste us dumped in a tipping area 2. compostable and noncompostable materials are separated 3. noncompostable material is removed to landfill 4. compostable material is aerated and turned one or more times for a period of 30 days to a year 5. composted material is allowed to cure 6. finished compost is transported for use
leachate -water that leaches through the solid waste and removes various chemical compounds which it comes into contact
sanitary landfills engineered ground facilities designed to hold MSW with as little contamination of the surrounding environment as possible
What are the layers of sanitary landfills? -clay/plastic lining at bottom -pipes constructed below to collect leachate -cover of soil and clay (cap) at top when landfill reaches capacity
Why is rainfall and other water inputs minimized in sanitary landfills? -cause greater rate of anaerobic decomposition and methane release -greater likelihood of leachate
What types of waste should not go in a landfill? aluminum and other metals, toxic materials, organic materials -anything that contains substantial quantities of metals
Process of a landfill 1. solid waste transported to the landfill 2. waste is compacted by a specialized machine 3. leachate collection system removes water and contaminants and carries them to a wastewater treatment plant 5. methane produced in closed cells is extracted and either burned off or collected for use as fuel
How are landfill construction fees recovered? -tipping fees: fee charged for disposing of material in a landfill or incinerator
Where should a sanitary landfill be located? -soil rich in clay -away from rivers, streams, and other water bodies -far from population centers, but not to far
What problems are caused by landfills? -locating landfills near populations who do not have the resources to object -possibility of leachate contaminating water -anaerobic decomposition produces greenhouse gases and explosion hazards
incineration process of burning waste materials to reduce the volume and mass and sometimes to generate electricity or heat -efficient incinerators may reduce the volume of solid waste by 90% and weight by 75%
Process of mass burn MSW incinerator 1. MSW sorted, recyclables diverted 2. remaining material is tipped into refuse bunker and certain materials are removed 3. crane transfers waste from bunker to hopper 4. waste burned in incineration chamber and combustion releases water and CO2 5. ash is collected and removed from plant 6. baghouse filter cleans air before it is released through chimney 7. heat energy can be used to create steam and generate electricity
ash residual nonorganic material that does not combust during incineration
bottom ash residue collected underneath the furnace
fly ash residue collected beyond the furnacr
waste to energy -heat generated by incineration is used rather than released to the atmosphere
What are the problems with incineration? -higher tipping fees ($70 per ton) -NIMBY and environmental justice issues -air pollutants -concentrated and toxic ash -large and expensive to build -require large daily MSW amounts to be efficient and profitable=less likely to encourage recycling -,ay not completely burn all waste
hazardous waste -liquid, solid, gaseous, or sludge waste that is harmful to humans or ecosystems
What are some sources of hazardous waste? industrial processes, dry cleaners, automobile service stations, small farms, households
Resource Conservation and Recovery Act RCRA -1970s -protect human health and environment by reducing or eliminating generation of hazardous waste -EPA maintains lists of hazardous wastes and works with businesses and state/local authorities to minimize and track hazardous waste -modified in 1984 to Hazardous Solid Waste Amendments HSWA to encourage waste minimization and phase out disposal of hazardous wastes on land, increase punishment of violators
Comprehensive Environmental Response, Compensation, and Liability Act CERCLA (Superfund Act) -passed 1980 amended 1986 -tax on chemical and petroleum industries -revenue from tax used to fund cleanup of abandoned and nonoperating hazardous waste sites -fed gov can respond directly to release or threat of release of toxic substances -National Priorities List NPL of contaminated sites eligible for funds
Brownfields Program -assists state and local gov in cleaning up contaminated land that did not achieve conditions necessary to be in Superfund category -brownfields: contaminated industrial or commercial sites that may require environmental cleanup before they can be redeveloped or expanded -management varied from region to region since it is run by state and local govs
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