8.9 - Solid Waste Disposal Flashcards
Solid Waste Types and Sources
MSW (Municipal Solid Waste)
- Solid waste from cities (households, businesses, schools, etc.
- Waste “stream” refers to flow of solid waste to recycling centers, landfills, or trash incineration (burning) facilities
- Aka - trash, litter, garbage, refuse
E-Waste
- Old computers, TVs, phones, tablets
- Only ~2% of MSW; considered hazardous waste due to metals like cadmium, lead, mercury, and PBDEs (fireproof chemicals)
- Can leach endocrine disrupting chemicals out of landfills if thrown away with regular MSW (should be disposed of at special facilities that recycle parts)
Sanitary Landfills
- APES lingo for “landfills” or where developed nations dispose of trash; different than “dumps” which are just areas where trash is dumped, without the features below
- Clay/plastic bottom liner: layer of clay/plastic on the bottom of a hole in the ground; prevents* pollutants from leaking out into soil/groundwater
- Leachate Collection System: System of tubes/pipes at bottom to collect leachate (water draining through waste & carrying pollutants) for treatment & disposal
- Methane Recovery System: System of tubes/pipes to collect that methane produced by anaerobic decomposition in the landfill
- Methane can be used to generate electricity or heat buildings - Clay Cap: Clay-soil mixture used to cover the landfill once it’s full; keeps out animals, keeps in smell, and allows vegetation to regrow
Landfills Contents and Decomposition
- Landfills generally have very low rates of decomposition due to low O2, moisture, and organic material combination
- Since these 3 factors are rarely present together in landfills, little decomp. occurs and landfills typically remain about the same size as when they were filled
Things that should not be landfilled:
- Hazardous waste (antifreeze, motor oil, cleaners, electronics, car batteries)
- Metals like copper & aluminum (should be recycled)
- Old tires; often left in large piles that hold standing water ideal for mosquito breeding
Things that should be landfilled:
- Cardboard/food wrappers that have too much food residue & can’t be recycled
- Rubber, plastic films/wraps
- Styrofoam
- Food, yard waste, and paper can and do go in landfills, but should be recycled or composted
Landfill Issues
- Landfills have environmental impacts like groundwater contamination and release of GHGs
- Groundwater can be contaminated with heavy metals (lead, mercury), acids, medications, and bacteria if leachate leaks through lining into soil/groundwater beneath
- Greenhouse gases (CO2 and CH4 - methane) are released from landfills due to decomposition; both contribute to global warming & climate change
- NIMBY (Not In My Back Yard) = idea that communities don’t want landfills near them for a number of reasons
- Smell & sight
- Landfills can attract animals (rats, crows)
- Groundwater contamination concerns
- Landfills should be located far from river & streams and neighborhoods to avoid H2O cont. - Landfills are often placed near low-income or minority communities that don’t have the resources or political power to fight against these decisions
Waste Incineration and Ocean Dumping
Waste can be incinerated (burned) to reduce the volume that needs to be landfilled; since most waste (paper, plastic, food) = hydrogen, carbon, and oxygen, it easily combusts at high temp.
- Can reduce volume by 90%, but also releases CO2 and air pollutants (PM, SOx, NOx)
- Bottom ash may contain toxic metals (lead, mercury, cadmium) & is stored in ash ponds, then taken to special landfills
- Toxic metals can leach out of storage ponds or be released into atmosphere
Can be burned to generate electricity
Illegal ocean dumping occurs in some countries with few environmental regulations or lack of enforcement
- Plastic especially collects into large floating garbage patches in the ocean
- Can suffocate animals if they ingest (eat) it or entangle them so they can’t fly or swim and may starve
