Solid and Hazardous Waste Notes

Reusing and Recycling Old Automobiles

  • In the U.S., 35 million vehicles leave service each year, with 11 million discarded.
  • Reuse and recycling minimize waste; steel is easily recycled, but many plastics are not.
  • Many major components from old automobiles can be reused in new ones.
  • Some automakers design vehicle parts for easy separation and recycling.
  • Since 2015, in Japan and the European Union, 95% of each car must be recyclable/recoverable.
  • A more sustainable strategy is to avoid reliance on automobiles.

Solid Waste

  • U.S. generates more solid waste per capita than any other country; in 2012, it was 1.99 kg per day. Canada is a close second.
  • Highly developed countries produce much more waste than less prosperous countries.
  • Materials thrown away would be repaired, reused, or recycled in less affluent nations.

Types of Solid Waste

  • Municipal solid waste:
    • Combined residential and commercial waste, less than 2% of total waste.
    • Discarded materials from homes, offices, stores, restaurants, schools, hospitals, prisons, libraries, and other commercial/institutional facilities.
    • Includes paper, paperboard, yard waste, plastics, food waste, metals, rubber, leather, textiles, wood, and glass.
  • Nonmunicipal solid waste:
    • Generated by industry, agriculture, and mining.

Solid Waste Trends

  • Until recently, total municipal solid waste production in the U.S. increased every five years.
  • Individual waste production increased, reaching a plateau around 1990.
  • The decrease in total and per-capita production from 2008 to 2012 is probably attributable to the economic downturn.

Disposal of Solid Waste

  • Solid waste is material no longer useful and should be disposed of.
  • Four disposal methods:
    • Dump it
    • Bury it
    • Burn it
    • Recover it

Open Dumps

  • Old, now illegal method.
  • Unsanitary, malodorous, host to rats, flies, etc.
  • Released methane gas, and hazardous materials leached to soil and groundwater.
  • Fires common, releasing acrid smoke.

U.S. Disposal of Municipal Solid Waste

  • Sanitary landfills:
    • Waste compacted and buried under a shallow soil layer.
  • Incineration:
    • Burning waste reduces volume by 90%.
  • Recovery:
    • Yard and food waste converted into compost; metals, paper, and plastic are recycled.

Sanitary Landfills

  • Replaced open dumps.
  • Receive 54% of municipal waste.
  • Designed not to pollute surface or groundwater.
  • Double-liner system:
    • Plastic, clay, plastic, clay layers.
    • Collects leachate and gases.
  • Strict guidelines and management, but still problems:
    • Methane production (can be collected for energy).
    • Leachate seepage from unlined landfills can contaminate water supplies.
    • Landfills fill up over time, and new ones are unwelcome.

Contemporary Sanitary Landfill

  • Require protective liners of compacted clay and high-density plastic.
  • Leachate collection systems minimize environmental problems.
  • Solid waste spread in a thin layer, compacted into cells, and covered with soil.

Special Problem of Plastic

  • Amount of plastic in solid waste is growing.
  • Packaging generates more than half the plastic in solid waste.
  • Chemically stable, doesn’t decompose.
  • Some areas banned certain plastics (PVC).
  • Alternatives:
    • Photodegradable: Degrade when exposed to light—doesn’t work if buried.
    • Biodegradable: Decomposed by microorganisms, but preliminary studies show it doesn’t work in landfills.

Incineration

  • Benefits:
    • Volume reduced by 90%.
    • Produces heat for warming buildings or generating electricity.
    • Best materials: paper, plastic, rubber.
    • 87 waste-to-energy incinerators in use in U.S. in 2012.
  • Problems:
    • Air pollution (CO, particulates, heavy metals, toxic materials).
    • Glass, food waste, and mercury-containing items must be removed.
    • Large quantities of ash require hazardous waste disposal.
    • Expensive due to costly pollution control devices.

Types of Incinerators

  • Mass burn incinerators:
    • Large furnaces burning all solid waste except unburnable items.
  • Modular incinerators:
    • Less expensive, pre-fabricated smaller incinerators.
  • Refuse-derived fuel incinerators:
    • Burn combustible portion of solid waste after removing non-combustibles.

Composting

  • Yard waste is a substantial portion of municipal solid waste.
  • Best recovery method is converting it into soil conditioners for nutrients.
  • Compost and Mulch.
  • Other compostables:
    • Food scraps, sewage sludge, agricultural manure.
  • Uses:
    • Landscaping in public parks and playgrounds.
    • Sold to gardeners.
    • Popular in Europe; now part of integrated waste management in U.S.

Reducing Solid Waste

  • Goals of waste prevention:
    • Reduce waste amount as much as possible.
    • Purchase products with less packaging, that last longer, or are repairable.
    • Decrease consumption— “Do I REALLY need it?”
    • Reuse products as much as possible.
    • Recycle materials as much as possible.

Source Reduction

  • Products designed and manufactured to decrease solid and hazardous waste.
  • Aluminum cans now 35% lighter than in the 1970s.
  • Dematerialization—making smaller, more durable products.
  • Reusing products:
    • Refillable glass beverage bottles.

Recycling Materials

  • Materials collected and processed into new products.
    • Conserves resources, more environmentally benign.
    • Every ton of recycled paper saves 17 trees, 7000 gallons of water, 4100 kwh of energy and 3 cubic yards of landfill space.
  • Generates jobs and revenues, but requires a market for recycled goods.
  • U.S. recycles about 34% of municipal solid waste.

Recycling Specific Materials

  • Recycling paper:
    • U.S. recycles 72% of paper and paperboard (Denmark—97%).
  • Recycling glass:
    • 33% of glass waste is recycled in U.S.
    • Recycled glass costs less than glass made from virgin materials.
    • Colors are separated before crushing to make cullet more valuable.

Recycling Metals

  • Aluminum:
    • 49% of aluminum beverage cans are recycled.
    • Requires less energy than making new cans from raw materials.
  • Other recyclable metals: lead, gold, iron, steel, silver, and zinc.
    • New steel products contain an average of 56% recycled scrap steel.

Recycling Plastic

  • 13% of plastic containers and packaging in the U.S. are recycled.
  • 37% of recycled soft drink bottles are used to make carpet, auto parts, tennis ball felt, polyester cloth.
  • Cheaper to make plastic from raw materials depending on petroleum prices.
  • 46 different plastic types are common; many are mixtures.
  • All must be separated before recycling.

Recycling Tires

  • Used for retread tires, playground equipment, trash cans, garden hoses, rubberized asphalt.
  • Also used in carpets, roofing materials, molded products.
  • Ongoing research in product development.
  • Can be burned in waste-to-energy incinerators to produce electricity.

Integrated Waste Management

  • Combines the best waste management techniques into a consolidated program.
    • Waste minimization, waste prevention (source reduction, reduce, reuse, recycle).

Hazardous Waste

  • Also called toxic waste.
    • 1% of solid waste stream in U.S.
  • Discarded chemicals that threaten human health or the environment.
    • Dangerously reactive, corrosive, ignitable, or toxic chemicals.
    • Solids, liquids, gases.
    • 700,000 different chemicals exist, most of unknown toxicity.

Love Canal Disaster

  • Hooker Chemical Company covered toxic dump, donated to school board in Niagara Falls, NY.
  • Toxic waste leaked into neighborhood, contaminated homes and people.
  • 700+ families evacuated.
  • Led to Superfund Act (CERCLA) in 1980.
    • Holds polluters accountable for cleanup costs.

Types of Hazardous Waste

  • Hazardous chemicals include a variety of acids, dioxins, explosives, heavy metals, infectious wastes, nerve gas, organic solvents, polychlorinated biphenyls (PCBs), pesticides, and radioactive substances.

Dioxins

  • Group of 75 similar chemicals produced from combustion of chlorine compounds.
  • Released primarily from incineration of medical and municipal wastes, and some industrial processes.
  • Incorporated in food web; humans ingest dioxins from contaminated meat, dairy, and fish.
  • Bioaccumulate in body fat.
  • Cause several kinds of cancer in lab animals.
  • Likely affect human reproductive, immune, and nervous systems; passed in human milk to infants.
  • Dioxin emission reduction measures show some success.

Polychlorinated Biphenyls (PCBs)

  • Group of 209 industrial chemicals.
  • Produced in U.S. from 1929–1979, had many uses.
  • Prior to 1970s ban by EPA, PCBs were dumped into landfills, sewers, fields. PCBs do not degrade rapidly; these are still dangerous today.
  • Serious health problems, liver/kidney damage, eyes, skin, reproduction.
  • Endocrine disrupters of thyroid gland, may be carcinogenic.
  • Several bacteria that degrade PCBs discovered; research continuing.

Handling Nanotechnology Safely

  • Nanomaterials—unique materials and devices at the ultrasmall scale of atoms and molecules.
  • Potential uses in medical treatment for cancer, solar panels to make electricity, heat-resistant glass.
  • Might pose health and safety risks.
  • EPA has adopted precautionary approach.
  • Burden of safety proof will be on companies that sell nanotechnology.

Managing Hazardous Waste

  • Hazardous wastes are extremely difficult to remove once released.
  • Costs of managing toxic wastes are high.
  • No country has an effective hazardous waste management program.
  • Eliminating production or using fewer hazardous substances are the most strategic methods.

Chemical Accidents

  • National Response Center (NRC) is notified.
  • On-scene coordinator determines the size and chemical nature of the incident.
  • Chemical safety programs stressed accident mitigation and adding safety systems.
  • More recently, focus is on accident prevention.
  • Principle of inherent safety—redesigning processes to make dangerous accidents less likely; a component of source reduction.

Public Policy and Toxic Waste Cleanup

  • Two federal laws cover hazardous waste management:
    • Resource Conservation and Recovery Act
    • Passed in 1976, amended in 1984.
    • Instructs EPA to identify hazardous wastes, provide guidelines/standards.
    • Requires waste to be treated to reduce toxicity before land disposal.
    • RCRA reformed in 1992 to encourage hazardous waste recycling.
    • Superfund Act—CERCLA
    • Comprehensive Environmental Response, Compensation, and Liability Act, established in 1980.
    • Deals only with waste produced in the past, not currently.
    • Provides for cleanup of abandoned and inactive hazardous waste sites.
    • Hazardous wastes have migrated deep into the soil and have polluted groundwater at many sites.
    • Over 10,000 sites in the CERCLA inventory.
    • Sites with greatest public health threat are placed on the Superfund National Priorities List.

Managing Toxic Waste Production

  • Most effective approach: source reduction.
    • Green chemistry: Redesigning chemical processes to reduce environmental harm.
    • Using less hazardous or nonhazardous materials.
  • Second best approach: reduce toxicity.
    • By chemical, biological, or physical means.
    • Incineration is an example, but ash is hazardous.
  • Third option: long-term storage (toxic waste landfills).

Toxic Waste Landfills

  • Subject to strict environmental criteria and design features.
    • Layers of compacted clay and plastic liners.
    • Leachate is collected and detoxified.
  • Deep-well injection:
    • For toxic liquid waste, such as explosives and pesticides.
    • Injected deep underground, between two impermeable layers.

High-Tech Waste

  • Average computer is replaced every 18–24 months due to rapid technological change.
  • Old computers work but have no resale value, often thrown away with regular garbage.
  • Large percentage of electronic devices go to landfills, wasting plastics and metals, including toxic compounds.
  • Recent tech (LCD monitors) reduced lead content, but cadmium, mercury, copper, tin, palladium, etc., are still present.
  • About 40% of electronics are e-cycled, but only 10% of mobile devices.
  • Many are shipped overseas for recycling, often in hazardous working conditions.