8.8 Solid Waste Disposal

Where solid waste goes

Solid waste includes municipal, industrial, and construction waste. Most is buried in sanitary landfills, which use clay/plastic liners and caps to prevent leachate from contaminating groundwater. Older open dumps lack these protections. Landfills also produce methane as waste decomposes anaerobically, which can be captured for energy or contribute to greenhouse gas emissions if released.

Incineration and its trade-offs

Incineration burns waste, reducing volume by up to 90% and can generate electricity (waste-to-energy). However, it releases air pollutants like dioxins, particulates, and CO2, and produces toxic ash that requires disposal. It's often chosen where land for landfills is scarce.

Reducing waste: the 3 R's and composting

The waste management hierarchy prioritizes reduce, reuse, recycle (in that order) to minimize the amount sent to landfills or incinerators. Composting breaks down organic waste (food scraps, yard waste) aerobically into nutrient-rich material, diverting biodegradable waste and reducing methane production from landfills.

Key terms

Sanitary landfill

Waste disposal site with liners and caps designed to prevent leachate contamination of groundwater.

Leachate

Toxic liquid produced as waste decomposes; can contaminate soil and groundwater if not contained.

Incineration

Burning solid waste to reduce volume (up to 90%); can generate electricity but releases air pollutants and toxic ash.

Composting

Aerobic decomposition of organic waste into nutrient-rich material, reducing landfill methane production.

3 R's (waste hierarchy)

Reduce, reuse, recycle — prioritized in that order to minimize waste sent to landfills/incinerators.

Try an AP-style question

Why do sanitary landfills have clay and plastic liners?

1. To speed up decomposition
2. To keep leachate out of groundwater
3. To increase methane production
4. To lower the cost of hauling