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. . .