Solid Waste Disposal and Waste Reduction

Vocabulary practice flashcards covering AP Environmental Science concepts from Topic 8.9 (Solid Waste Disposal) and Topic 8.10 (Waste Reduction), including municipal solid waste characteristics, sanitary landfill engineering, environmental impacts, the Three Rs, composting dynamics, and relevant environmental legislation.

Municipal Solid Waste (MSW)

Solid waste generated exclusively by humans from urban areas such as households, businesses, and schools; commonly referred to as trash, litter, garbage, or refuse.

Throw Away Society

A human society characterized by consumer behavior oriented toward single-use or replacement products rather than reusing and repairing existing items.

Waste Stream

The total flow of solid waste from its initial point of generation to destination facilities such as recycling centers, sanitary landfills, or incineration plants; approximately $\frac{1}{3}$ consists of paper and approximately $\frac{2}{3}$ consists of organics (compostable material).

E-Waste

Discarded electronic devices (such as computers, televisions, mobile phones, and tablets) that constitute roughly $2\%$ of MSW and are classified as hazardous waste due to toxic metals like cadmium, lead, and mercury, as well as flame retardants like PBDEs.

Sanitary Landfill

An engineered waste disposal site utilized by developed nations that isolates solid waste from the surrounding environment using protective features such as bottom liners, leachate recovery, methane collection, and a top cap.

Clay/Plastic Bottom Liner

A protective barrier made of a dense layer of clay or thick plastic lining the floor of a landfill designed to prevent toxic pollutants from leaking into underlying soil and groundwater.

Leachate

A contaminated, toxic liquid generated when surface water or precipitation drains downward through solid waste, leaching dissolved and suspended pollutants out of the landfill.

Leachate Collection System

A drainage network of tubes or pipes located along the bottom of a sanitary landfill that collects leachate and transports it to a specialized treatment facility for safe disposal.

Methane Recovery System

A network of collector pipes engineered to capture methane ($CH_4$) gas produced by anaerobic microbial decomposition within a landfill so it can be burned to heat buildings or generate electricity.

Clay Cap

A sealed top layer composed of a clay-soil mixture installed over a landfill once it reaches capacity to contain foul odors, exclude scavenging wildlife, and allow vegetation to grow.

Landfill Decomposition Limitation

The extremely slow rate at which trash breaks down inside a sanitary landfill because the three necessary conditions—oxygen ($O_2$), sufficient moisture, and organic matter—are rarely present together.

NIMBY (Not In My Back Yard)

A sociological phenomenon in which local community residents oppose the siting of undesirable facilities—such as landfills—in their vicinity due to repulsive smells, unsightly views, attraction of pests (like rats and crows), and groundwater contamination risks.

Environmental Injustice in Landfill Siting

The disproportionate placement of sanitary landfills and waste facilities adjacent to low-income or minority communities that lack the financial resources or political influence to contest municipal decisions.

Waste Incineration

The combustion of solid waste at high operating temperatures that reduces total waste volume by approximately $90\%$, while releasing carbon dioxide ($CO_2$) and air pollutants like particulate matter (PM), $SO_x$, and $NO_x$.

Bottom Ash

The residual, non-combustible material remaining after waste incineration that often contains concentrated toxic heavy metals (such as lead, mercury, and cadmium) and must be placed in ash storage ponds or lined hazardous waste landfills.

Illegal Ocean Dumping

The unlawful disposal of municipal and industrial waste directly into the sea, which forms vast floating oceanic garbage patches and causes marine animal mortality through ingestion, suffocation, and entanglement.

Source Reduction (Reducing)

The practice of decreasing personal and industrial consumption of manufactured goods; recognized as the most sustainable of the Three Rs because it prevents the raw resource harvesting, manufacturing, packaging, and shipping stages entirely.

Reusing

The process of repeatedly using an item in its original form without reprocessing it (such as secondhand clothing or refilled containers), representing the second most sustainable option among the Three Rs because no extra manufacturing energy is consumed.

Recycling

The mechanical and chemical reprocessing of collected waste materials to manufacture brand-new goods; considered the least sustainable of the Three Rs due to significant energy inputs required for collection, sorting, and reprocessing.

Closed-Loop Recycling

A recycling process in which a discarded product is converted back into the identical original product type, such as melting discarded glass bottles to manufacture new glass bottles.

Open-Loop Recycling

A recycling process in which a post-consumer material is converted into a completely different product type, such as reprocessing polyethylene plastic water bottles into polyester fleece fibers for jackets.

Composting

The controlled aerobic biological breakdown of organic materials (including food scraps, yard waste, and paper) into a dark, nutrient-rich soil amendment that improves the water-holding capacity and fertility of garden or agricultural soils.

Carbon-to-Nitrogen Ratio (Browns to Greens)

The optimal ratio of approximately $30:1$ of carbon-rich 'brown' materials (such as dried leaves and paper) to nitrogen-rich 'green' materials (such as fresh food scraps) required to maintain balanced microbial decomposition in compost piles.

Waste-to-Energy (WTE)

A facility or system that harnesses heat released from incinerating municipal solid waste or burning recovered landfill methane to boil water into steam, driving a turbine and generator to produce electricity.

Resource Conservation and Recovery Act (RCRA)

Federal legislation granting the Environmental Protection Agency (EPA) regulatory authority to manage hazardous waste across all stages—generation, transportation, treatment, storage, and disposal—while a facility is actively operating.

Comprehensive Environmental Responsibility Compensation and Liability Act (CERCLA)

A federal law that specifically authorizes and funds the identification, assessment, and remedial cleanup of abandoned or closed hazardous waste sites.