Solid waste is a growing challenge in our modern world. From packaging to food scraps, we generate tons of trash daily. This section explores how we handle all that waste, from what goes in our garbage to where it ends up.

Landfills and incinerators are common disposal methods, but they come with drawbacks. We'll look at how these facilities work and their environmental impacts. We'll also explore alternatives like composting that can turn waste into a resource.

Waste Types and Characterization

Municipal Solid Waste Composition

• Municipal solid waste encompasses discarded materials from residential, commercial, and institutional sources
• Consists of everyday items like packaging, food scraps, yard trimmings, and durable goods (furniture, appliances)
• Composition varies by region and socioeconomic factors
• Typical breakdown includes:
  • Paper and cardboard: ~25-30%
  • Food waste: ~15-20%
  • Plastics: ~10-15%
  • Yard trimmings: ~10-15%
  • Metals: ~5-10%
  • Glass: ~5%
  • Other materials: ~10-15% (textiles, rubber, leather, electronics)

Waste Characterization Techniques

• Waste characterization involves analyzing the composition and quantity of waste generated
• Methods for waste characterization include:
  • Waste sorting studies separate and weigh different waste components
  • Surveys and questionnaires gather information on waste generation habits
  • Material flow analysis tracks the movement of materials through the economy
• Provides crucial data for waste management planning and policy development
• Helps identify opportunities for waste reduction, recycling, and resource recovery
• Enables monitoring of waste generation trends over time

Waste Stream Analysis

• Waste stream refers to the total flow of waste from its source to final disposal
• Analyzing the waste stream involves:
  • Identifying waste sources (households, businesses, industries)
  • Quantifying waste generation rates
  • Tracking waste movement through collection, transfer, and disposal systems
• Helps in designing efficient waste management systems
• Allows for targeted interventions to reduce waste at specific points in the stream
• Supports the development of circular economy initiatives by identifying potential resource recovery opportunities

Landfills

Landfill Design and Operation

• Landfill serves as an engineered facility for the disposal of solid waste
• Modern landfills incorporate multiple protective layers:
  • Bottom liner system prevents leachate from contaminating groundwater
  • Daily cover material reduces odors and prevents waste from blowing away
  • Final cap system seals the landfill after it reaches capacity
• Waste placement involves:
  • Compacting waste to maximize space utilization
  • Covering waste with soil or alternative materials daily
• Monitoring systems track environmental impacts (groundwater quality, gas emissions)
• Closure and post-closure care ensure long-term environmental protection

Sanitary Landfill Features

• Sanitary landfill improves upon traditional dump sites with engineered controls
• Key features include:
  • Careful site selection to minimize environmental impact
  • Impermeable liners (clay or synthetic materials) to prevent groundwater contamination
  • Leachate collection and treatment systems
  • Gas collection systems for methane capture
  • Systematic filling and compaction of waste
  • Regular monitoring of environmental parameters
• Designed to meet strict regulatory requirements and environmental standards
• Reduces public health risks associated with waste disposal

Leachate and Gas Management

• Leachate forms when water percolates through waste, picking up contaminants
• Leachate management involves:
  • Collection systems with perforated pipes and drainage layers
  • On-site treatment facilities or transport to wastewater treatment plants
  • Monitoring of leachate quantity and quality
• Landfill gas primarily consists of methane and carbon dioxide
• Methane capture systems include:
  • Vertical wells or horizontal pipes to collect gas
  • Blowers to create negative pressure and extract gas
  • Flaring systems to burn excess gas
  • Potential energy recovery through electricity generation or direct use

Alternative Disposal Methods

Incineration Technology and Benefits

• Incineration involves controlled burning of waste at high temperatures (800-1000°C)
• Modern incinerators include:
  • Combustion chamber for waste burning
  • Air pollution control systems (scrubbers, filters) to reduce emissions
  • Energy recovery systems to generate electricity or heat
• Benefits of incineration:
  • Significant volume reduction (up to 90%) of waste
  • Destruction of pathogens and hazardous organic compounds
  • Energy recovery potential (waste-to-energy facilities)
  • Reduced need for landfill space
• Challenges include high initial costs and public concerns about emissions

Composting Processes and Applications

• Composting biodegrades organic waste into nutrient-rich soil amendment
• Composting methods include:
  • Windrow composting for large-scale operations
  • In-vessel composting for controlled environments
  • Vermicomposting using worms to break down organic matter
• Process involves:
  • Mixing of organic materials (food scraps, yard waste)
  • Controlling moisture, temperature, and oxygen levels
  • Microbial decomposition over several weeks or months
• Applications of compost:
  • Soil improvement in agriculture and gardening
  • Erosion control in landscaping
  • Remediation of contaminated soils
• Diverts organic waste from landfills, reducing methane emissions
• Produces valuable product for soil enhancement and carbon sequestration