Solid, Toxic, and Hazardous WasteChapter 21 Notes

Solid Waste

Municipal Waste- a combination of household and commercial refuse- amounts to more than 200 million metric tons per year in the US

Newspapers, magazines, catalogs, and office refuse make paper one of our major wastes

Waste stream- steady flow of varied wastes that we all produce, from domestic garbage and yard wastes to industrial, commercial, and construction refuse

Why is it important to separate hazardous materials from the main waste stream?

Waste Disposal Methods (improper)

Open dumps (unregulated) release hazardous materials into air and water. How?

Ocean dumping is nearly uncontrollable. Why?

(20 million tons of plastic debris ends up in the ocean each year)

We often export waste to countries ill-equipped to handle it (toxic colonialism)

Since 1989 it has been illegal to export electronic waste or e-waste, but about 80% of our e-waste is shipped overseas, mostly to China and other developing countries in Asia and Africa.

Outdated electronic devices are one of the greatest sources of toxic material currently going to developing countries.

Waste Disposal Methods (Better)

Sanitary landfills- where solid waste in contained more effectively by lining the landfill, compacting the refuse, and covering it each day with a layer of dirt

Landfills are being built away from rivers, lakes, floodplains, and aquifer recharge zones rather than near them.

(landfilling is still the disposal method for the majority of municipal waste is the US)

Incineration produces energy but causes pollution; high levels of dioxins, furans, lead, and cadmium are found in incinerator ash.

Energy recovery, or waste to energy, is used in incinerators to derive heat as a useful resource.

Shrinking the Waste Stream

Recycling captures resources from garbage

Recycling plastic though is especially difficult

Contamination from PVC (polyvinyl chloride) can contaminate a truckload of plastics made from PET (polyethylene terephthalate) that is more easily recycled

(reason for numbers on the bottom of plastic containers)

Recycling saves money, materials, and energy

Curbside pickup of recyclables costs around $35 per ton, as opposed to the $80 paid to dispose of them at an average metropolitan landfill

Cuts our waste volume so we can reduce the number of landfills and incinerators and the energy to run them

Shrinking the Waste Stream

Composting- the most common large-scale recycling of municipal yard waste and tree trimmings.

Demolition and construction debris is another major source of waste, but recycling facilities are beginning to collect, sort, and resell increasing portions of this debris.

Demanufacturing- is the disassembly and recycling of obsolete products, such as TV sets, computers, refrigerators, and air conditioners

Demanufacturing is key to reducing the environmental costs of e-waste and appliances.

Shrinking the Waste Stream

Reuse is even more efficient than recycling because it saves the cost and energy of remaking them into something else

But national companies favor recycling rather than refilling, why?

Reducing waste is often the cheapest option

Excess packaging of food and consumer products is one of our greatest sources of unnecessary waste (it makes up 50% of our domestic trash by volume)

Using photodegradable or biodegradable plastics helps to reduce the waste volume

Hazardous and Toxic Wastes

Hazardous waste is any discarded material, liquid, or solid, that contains substances known to be

1. fatal to humans or laboratory animals in low doses

2. toxic, carcinogenic, mutagenic, or teratogenic to humans or other life forms

3. ignitable with a flash point less than 60 degrees Celcius

4. corrosive

5. explosive or highly reactive (undergoes violent chemical reactions either by itself or when mixed with other materials)

Hazardous and Toxic Wastes

Two important federal laws regulate hazardous waste management and disposal in the US

The Resource Conservation and Recovery Act of 1976 (RCRA)

Requires rigorous testing and management of toxic and hazardous substances

The Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA or Superfund Act)

Aimed at rapid containment, cleanup, or remediation of abandoned toxic waste sites

Toxic Release Inventory- more than 20,000 manufacturing facilities are required to report annually on the use, release, or transfer of toxic substances

Brownfields- large areas of contaminated properties

Up to 1/3 of all commercial and industrial sites in the urban core of many big cities fall in this category

Hazardous Waste Storage must be safe

1. Produce less waste

2. Store Permanently

Retrievable storage- placing waste storage containers in a secure building, salt mine, or bedrock cavern where they can be inspected periodically and/or retrieved

Secure landfills

3. convert substances to less hazardous forms

Physical treatments- tie up or isolate substances (filters, distillation, precipitation)

Incineration

Chemical processing- neutralization and oxidation

Bioremediation- use of microorganisms to absorb, accumulate, and detoxify a variety of toxic compounds