waste generation & waste disposal ch 16. what is solid waste? outputs in human systems that...
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Waste Generation & Waste Disposal
Ch 16
What is Solid Waste?• Outputs in human systems that include
anything not useful or consumed, and non-useful products generated within the system.
Throw-Away Society• In 1900, all metal, wood, and glass materials
were recycled.• After WWII, consumption patterns changed:
– Cultural & wealth changes– Industrialization– Bought “labor saving” appliances that were
disposed of when new model was available.– Planned obsolescence –design of a product that
will have to be replaced within a few years.– Ex: TV dinners, disposable napkins, disposable
diapers
Municipal Solid Waste (MSW)
• Refuse collected by cities from households, businesses & institutions
• EPA estimates 60% from residence & 40% from commercial & institutional facilities
• Estimated in US avg. waste generation per person is 4.5 lbs./day
• US generated approx. 200 million metric tons (506 billion pounds) per year!!!!
• Fastest growing waste in US• 2% of waste
– Environmental effect is far greater than the number imples
• 1 CRT computer monitor contains 2-2.5 pounds of lead, mercury and cadmium
• Expensive to recycle (often shipped to China)– 18% of TV and Computer
products are sent to recycling facilities
E-Waste
3R’s??
• Reduce and Refuse– Consume less, do not buy items you don’t need,
use less single time use products• Reuse and Repurpose
– Rely on items that can be used over and over or used for something else
• Recycle – Conversion of products from one substance into
another
Reduce
• 1st choice because reducing inputs is the optimal way to achieve a reduction in MSW.– Input is reduced, therefore output is reduced.– Source reduction – reducing the early stages of
design & manufacture, the use of materials.– Less waste, fewer resources used, increase energy
efficiency– Ex: reduce packaging & material substitution
Reuse• Allows material to cycle within a system longer
before becoming an output• No additional energy or resources is needed• May require repairing the object costing time,
money, labor & energy• Energy may be required to prepare for reuse
– Ex: Reuse of beverage containers (Coke, milk bottles) – clean, sterilize & transport; tires; newspapers
– Flea markets, swap meets, eBay, Craigslist, thrift stores
How People Reuse Materials• Children looking for
materials to sell in an open dump near Manila in the Philippines.
• 2 liter bottles are being installed to provide light to houses during the day
REUSE• ENERGY
CONSUMPTION• Reusing:
– Extends resource supply
– Reduces energy use
– Maintains high quality matter
Figure 22-7Figure 22-7
Solutions: Other Ways to Reuse Things
• Shopping bags– Many countries in Europe and Asia charge shoppers
for plastic bags.
• Food containers• Drink containers• Shipping pallets• Borrow tools from tool libraries.• Buy clothes at thrift shop or consignment stores
Recycling
• Closed-loop recycling –– Recycling a product into the same product
indefinitely– Ex: Aluminum
• Open-loop recycling –– Recycling a product into another product– Ex: Plastic bottles into polar fleece jackets– It does not reduce the demand for the raw
material
Reusing Plastic ?• 1 – PET – Water Bottles, Single and multiuse, little evidence of
leeching
• 2 – HDPE – Milk Containers, 1 use, does not leech chemicals
• 3 – V – PVC, not for consumption (dioxins/pthalates)
• 4 – LDPE –5 – PP• 6 – PS – styrofoam (don’t microwave, consume
fatty foods or alcoholic beverages) styrene• 7 – Other – Hard plastic containers, multiple uses, can have BPA
Recycling Plastic• Chemically and Economically
Difficult– 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.
Yucatan Trash
Recycling Plastic• Why do it?
– It is 1/10th cheaper to make plastic products out of recycled plastic• Removes waste from landfills• Less plastics in ocean• Keeps toxic chemicals from entering the environment
– #3 PVC – phthalates and dioxins– #7 Other – BPA, phthalates
• BUT, it is not a closed loop recycling• OR – REDUCE plastic consumption
Composting• Equal, if not more important than the three
R’s• Organics in landfills cause two problems:
– Take up space– Decompose anaerobically (no O2) & produce
methane gas
• Composting – organic matter that is decomposed under controlled conditions to produce organic-rich material for gardens/crops
Composting• What can be composted?
– Vegetables & vegetable by-products– Yard waste, animal manure
• What cannot:– Meat & dairy because takes long to decompose
and has foul odor.
• Rapid decomp needs C:N ratio of 30:1• To make sure process is aerobic, agitation and
moisture are needed
What do we do with MSW?
• 1930’s public opposition to open trash dumps.• Sanitary landfills:
– Engineered ground facilities designed to hold MSW with little contamination.
– Leachate – water that leaches (passes through) the solid waste & removes various chemical compounds
• Harmful• Can be transported outside of the dump/landfill
Fate of MSW in US. Majority is disposed in landfills
Sanitary Landfills• Lined at bottom with plastic or clay
(impermeable-impedes water flow)• System of pipes below landfill to collect
leachate• Cover of soil & clay called a cap to cover
landfill when it reaches capacity• Material destined for landfills are those least
likely to cause environmental damage.– Ex: Plastic, paper, inter materials = yes;
chemicals, electronics, organics, metal = no!
Sanitary Landfills
• Once filled to capacity, it is closed & capped.• Water is minimized to reduce odor & slow
decomp.• Closed landfills can be reclaimed:
– Parks, playgrounds & golf courses built on them
• Costly –– Paid for by a tipping fee (trucks are weighed and
tipped into landfill; $35/ton
Problems with Landfills
• Possibility of leachate contamination of soil & groundwater.
• Once covered anaerobic decomposition occurs producing methane (CH4) & CO2 – Greenhouse gases & methane is explosive– Methane must be collected; can be used as fuel
• Decomp. Rates – very slow (40+) years; need correct mixes of air, moisture & organic material.
Sanitary Landfill
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Advantages
No open burning
Little odor
Low groundwaterpollution if sitedproperly
Can be builtquickly
Low operatingcosts
Can handle largeamounts of waste
Filled land canbe used for otherpurposes
No shortage oflandfill space inmany areas
Disadvantages
Noise and traffic
Dust
Air pollution fromtoxic gases andvolatile organiccompoundsreleasegreenhousegases (methaneand CO2)
Groundwatercontamination
Slowdecompositionof wastes
Encourages waste production
Eventually leaksand cancontaminategroundwater
Figure 21-13Page 545
Incineration• Process of burning waste material to reduce
volume & mass & produce energy.– Reduce volume by 90% & mass by 75%
• Sorted MSW is tipped into incinerator– CO2 & water are released into atmosphere
• Particulates are end products of combustion– Ash is residual nonorganic material; bottom
furnace ash is called bottom ash & residue beyond furnace is fly ash
Problems with Incineration
• Tipping fees are higher ($70/ton)• NIMBY issues:
– Releases pollutants– Produce ash that is more toxic than waste– Odor– Discourages recycling– Inconsistent burn (different materials)– Releases greenhouse gases (CO2)
Fig. 22-11, p. 531
Reduces trash volume
Can compete with recycling for burnable materials such as newspaper
Output approach that encourages waste production
Older or poorly managed facilities can release large amounts of air pollution
Some air pollution
Difficult to site because of citizen opposition
Costs more than short-distance hauling to landfills
Expensive to build
Some facilities recover and sell metals
Modern controls reduce air pollution
Sale of energy reduces cost
Concentrates hazardous substances into ash for burial or use as landfill cover
Low water pollution
Less need for landfills
Trade-Offs
Incineration
Advantages Disadvantages
Hazardous Waste• Solid or Liquid• Contains 1 or more of 39 mutagenic, carcinogenic or
teratogenic compounds above established limits.– ORGANIC: Pesticides, PCB’s, Dioxins and INORGANIC: Heavy
Metals• Catches fire easily
– Gasoline, paints, solvents• Reactive or explosive or releases toxic fumes
– Acids, bases, ammonia and bleach• Corrosive
– industrial cleaners oven and drain cleaners
• US creates 75% of Hazardous Waste• RCRA – Resource Conservation and Recovery Act 1976
Distribution of NPL (Superfund) sites in US
Not Hazardous Wastes Radioactive wastes Radioactive wastes Household wastes Household wastes Mining wastes Mining wastes Oil and gas drilling wastes Oil and gas drilling wastes Liquids containing organic hydrocarbons Liquids containing organic hydrocarbons Cement kiln dust Cement kiln dust
See Table 21-1 p. 527See Table 21-1 p. 527
<100 kg (220 lb) per month <100 kg (220 lb) per month Therefore hazardous waste laws do not
regulate 95% of the country’s hazardous waste
Therefore hazardous waste laws do not regulate 95% of the country’s hazardous waste
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:• natural or genetically engineered plants absorb, filter and
remove contaminants from polluted soil and water.
Hazardous Waste• Land Disposal
– In ground– Above ground
• Exporting– Canada– Shipping to developing countries, Basel convention
• Khian Sea, Philadelphia to Haiti
Deep-well Disposal of Liquid Hazardous Waste
Fig. 21-14p. 546
Above Ground Hazardous Waste Disposal
Fig. 21-17p. 547
Regulations• RCRA
– control hazardous waste from the "cradle-to-grave." This includes the generation, transportation, treatment, storage, and disposal of hazardous waste. RCRA also set forth a framework for the management of non-hazardous solid wastes. The 1986 amendments to RCRA enabled EPA to address environmental problems that could result from underground tanks storing petroleum and other hazardous substances.
• CERCLA, Superfund– provides a Federal "Superfund" to clean up uncontrolled or abandoned hazardous-
waste sites as well as accidents, spills, and other emergency releases of pollutants and contaminants into the environment. Through CERCLA, EPA was given power to seek out those parties responsible for any release and assure their cooperation in the cleanup.
• Toxic Substance Control Act– reporting, record-keeping and testing requirements, and restrictions relating to
chemical substances and/or mixtures. Certain substances are generally excluded from TSCA, including, among others, food, drugs, cosmetics and pesticides.
• Stockholm Convention– 12 POP’s (DDT, PCBs, Dioxins, many pesticides/fungicides)
What do we do with Brownfields?
• Redevelopment of land complicated by presence of hazardous chemicals– Clean-up and Reinvest
• Brownfield Revitalization - amendment to CERCLA• Gives funds to clean-up and use underutilized areas• Reduces blight
– creates parks, neighborhoods, shopping areas etc. . .