Environmental Science / Unit 9: Waste and Sustainability
9.1 Municipal Solid Waste
Notes
Municipal solid waste (MSW) is the trash from homes, schools, and businesses.
- In the US, each person generates about 4.5 to 5 pounds of MSW per day. The largest categories by weight are paper and paperboard, food waste, plastics, and yard trimmings.
- Common disposal methods: landfills (most US waste), incineration (burning, sometimes with energy recovery), recycling, and composting.
- A sanitary landfill has a liner, a leachate collection system, daily soil cover, and methane monitoring. Leachate is liquid that drains through waste and can contaminate groundwater. Landfills release methane, which can be captured as fuel.
- Incineration reduces waste volume by about 90% but produces ash and air pollutants, and uses scrubbers and filters.
- The waste hierarchy: reduce, reuse, recycle, recover energy, dispose.
- Example: a town with 30,000 people producing 5 lb each per day generates $30{,}000 \times 5 = 150{,}000$ lb per day.
Practice
What is leachate?
Liners and collection systems are designed to keep leachate out of groundwater.
In the waste hierarchy, which option is the most preferred?
Not creating waste prevents all later impacts.
A city of 100,000 people produces 4.5 pounds of waste per person per day. How much does it produce per day?
$100{,}000 \times 4.5 = 450{,}000$ lb.
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