unit 3

• Liquid waste


  Waste containing human excreta and sewage
• Excreta


  Waste containing human feces and urine
• Proper disposal of human excreta in a sanitary manner improves community health and prevents diseases
• Components of sewage


  • Liquid waste
  • Feces
  • Urine
  • Other waste
• Proper disposal of excreta

  Breaks the chain of disease transmission
• Human excreta can cause about 50 common diseases
• Classification of excreta-borne diseases


  • Helminthic
  • Protozoal
  • Bacterial
  • Viral
• Proper excreta disposal


  Reduces disease incidence and improves health
• Economic benefits of proper excreta disposal


  Increased life span and productivity
• Common methods of excreta disposal

  • Non-water carriage systems
  • Water carriage systems
• Bucket latrine


  One of the oldest and generally least hygienic latrine where excreta is deposited in a movable bucket or box
• Water carriage disposal system

  A system where excreta is deposited into sanitary appliances and immediately carried away by water through sewer lines to a final disposal site
• Factors for selecting water carriage disposal system

  • Quality of sewage
  • Degree of treatment needed
  • Nature of soil
  • Presence of reliable water source
  • Water table level
  • Proximity to surface water
  • Relative cost
• Cesspool


  A covered pit for collecting excreta and liquid waste, functioning either as a leaching type or water-tight type
• Seepage pit or soak away

  A hole filled with stone for waste water to seep into the surrounding soil from places like laundries, bathrooms, and kitchens
• Septic tank


  A construction where waste water takes days to pass through, allowing solids to settle forming sludge, requiring cleaning every 1-4 years
• Objectives of sewage treatment

  • Control excreta-borne diseases
  • Maintain water sources
  • Maintain ecological balance
  • Maintain aquatic ecosystems
  • Convert waste water into a useful resource
• Principle of sewage treatment


  1. Separating solid components

  2. Stabilizing sewage through bacterial or chemical processes

  3. Converting sewage to an inert state

  4. Destroying pathogenic organisms
• Types of sewage treatment

  • Primary (grit chamber, settling, etc.)
  • Secondary or biological (tricking filter, activated sludge)
  • Advanced (carbon filter, chemical treatment)
• Ways to reuse or recycle human excreta

  • Agriculture as compost or soil conditioner
  • Biogas production
  • Aquaculture to enrich water bodies for aquatic life
• Solid waste management


  Managing all wastes generated by human activities, specifically referring to wastes arising in solid form
• Solid waste (according to WHO)


  Useless, unwanted or discarded material arising from man's activities that are not free floating
• Adverse impacts of solid waste on the environment

  • Contamination of soil
  • Water pollution
  • Air pollution
  • Spread of disease by vectors living on waste
• Objectives of solid waste management

  • Vector control
  • Nuisance reduction
  • Aesthetic improvement
  • Fire protection
  • Pollution prevention
• Phases of solid waste management

  • Solid waste storage
  • Collection and segregation
  • Disposal
• Neglecting one phase of refuse management leads to the overall effectiveness of waste management failing
• Phases of solid waste collection

  • Generation portion
  • Transportation portion
• Methods of solid waste disposal

  • Composting
  • Open dumping
  • Sanitary landfill
  • Incineration