APES Unit 8

Definition of Solid Waste

• Municipal Solid Waste (MSW): Refers to household, commercial, and institutional waste (not specific to environmental studies).

• Synonyms: Trash, litter, refuse (important for exams).

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Sources of MSW

• Households

• Businesses

• Schools

Waste Stream

• The waste stream encompasses all solid waste produced.

• Common fates of waste include:

  • Recycling centers

  • Landfills

  • Incineration

Composition of MSW

• Approximately 33% paper (recyclable)

• Two-thirds organic (opportunity for composting)

E-Waste

• E-waste: Discarded electronics, e.g., computers and phones.

• Represents only 2% of MSW but contains hazardous materials (lead, mercury, etc.) that can act as endocrine disruptors.

• Proper disposal through specialized recycling is essential to prevent leaching.

Sanitary Landfills

• Sanitary Landfills: Controlled environments for solid waste disposal in developed nations. Different from a dump, which lacks safety measures.

• Key Features:

  • Clay/Plastic Liner: Protects groundwater by preventing pollutants from leaking out. Residual leakage often occurs.

  • Leachate Collection System: Manages leachate (contaminated water) to reduce pollution.

  • Methane Recovery System: Collects methane produced from anaerobic decomposition. Can be used for heating or electricity.

  • Clay Cap: Applied once landfill is filled to restore vegetation and limit interactions with wildlife.

Decomposition Rates in Landfills

• Decomposition is minimal in landfills due to low oxygen, moisture, and organic content.

• Examples of long-lasting materials in landfills:

  • Newspaper can remain legible for 40 years.

  • Fishing line decomposes over 600 years.

Items Not to Include in Landfills

• Hazardous Waste: Must not be disposed of in landfills (e.g., antifreeze, electronics) due to toxicity.

• Recyclables: Metals, plastics, and old tires are examples of items that should be recycled.

• Cardboard and food waste comprise a significant part of landfill content but can be diverted through recycling and composting.

Issues Related to Landfills

• Groundwater Contamination: Leachate may carry heavy metals and pollutants affecting nearby water sources.

• Greenhouse Gas Emissions: Landfills release CO2 and methane, contributing to climate change.

• NIMBY (Not In My Backyard): Communities resist landfill placement due to associated factors (sight, smell, vermin).

• Social Justice Issues: Landfills are often located in low-income communities or communities of color due to their limited resources to resist.

Waste Incineration and Ocean Dumping

• Waste can be incinerated to reduce waste volume by up to 90%.

• Concerns with Incineration:

  • Releases air pollutants and leaves behind bottom ash containing toxic materials (lead, mercury).

  • Bottom ash requires careful storage in monitored landfills.

• Ocean Dumping: Illegal dumping occurs where regulations are weak, contributing to pollution and health hazards for marine life (e.g., the Pacific garbage patch).

Waste Reduction Practices

1. Reduce

   • Most sustainable response to waste.

   • Minimizes energy input needed to create and distribute new goods.

   • Examples:

     • Using a reusable metal water bottle to cut down on plastic usage.

     • Riding a bike instead of driving to reduce gasoline consumption.

2. Reuse

   • Second most sustainable option.

   • Involves using a product without requiring energy for new materials.

   • Examples:

     • Washing and reusing plastic takeout containers.

     • Repurposing old wood pallets for furniture.

     • Purchasing secondhand clothing directly reused.

3. Recycle

   • Least sustainable of the three R's.

   • Involves processing waste into new materials, requiring energy input.

   • Types of Recycling:

     • Closed loop: Original material becomes the same product again (e.g., glass recycling).

     • Open loop: Material is transformed into different products (e.g., plastic bottles into jackets).

Pros and Cons of Recycling

• Advantages:

  • Reduces demand for new raw materials.

  • Conserves landfill space by decreasing waste disposal.

  • Especially effective when recycling metals and woods to prevent habitat destruction.

  • Reduces energy consumption in extraction, manufacturing, and distribution of raw materials.

• Disadvantages:

  • Recycling can be costly and energy-intensive.

  • Need for municipalities to process, package, and find buyers for recycled materials can be challenging.

  • Contamination issues with food residues can spoil batches of recycled materials.

Composting as a Waste Reduction Method

• Composting uses organic matter such as food scraps and yard waste.

• Nearly two-thirds of waste is compostable.

• Benefits of Composting:

  • Reduces landfill volume.

  • Produces nutrient-rich compost for soil enrichment.

  • Minimizes methane emissions from landfills through aerobic decomposition.

• Process of Composting:

  • Decomposing organic waste under controlled conditions (aerobic conditions with oxygen).

  • Mixing browns (carbon sources) and greens (nitrogen sources) enhances decomposition.

E-Waste: Importance and Management

• E-waste consists of hazardous materials found in electronics (e.g., lead, mercury).

• Improper management can lead to environmental contamination and health issues.

• Developed nations often export e-waste to developing countries, raising ethical concerns.

• Proper dismantling and recycling can reclaim valuable metals but often lacks safety and environmental regulations in poorer nations.

Waste-to-Energy Systems

• Waste incineration reduces volume and generates electricity.

• Combustible materials (paper, plastic, food) release energy when burned.

• Process of Energy Production:

  • Similar to thermal power plants: burning waste to produce heat, converting water to steam, and activating turbines for electricity generation.

  • Methane collection via landfill systems also captures gas for energy, although this method is less efficient than burning trash directly.

Summary of Waste Reduction Practices

• Effective waste reduction involves reducing, reusing, recycling, composting, and managing e-waste properly.

• Each method's efficiency varies, with reducing waste being the most sustainable choice.

• Understanding waste-to-energy opportunities provides an alternative for reducing landfill use while generating energy.