Composting

• What is composting?

  A biological transformation of biodegradable waste
• What does composting help to reduce?

  The volume of waste for landfill or incineration
• What valuable product does composting yield?

  A product for soil amendment and mulch
• How does properly processed compost improve soil?

  Improves soil nutrients and reduces erosion
• What are examples of compostable materials?

  Yard waste, food waste, manure
• What is the organic fraction of MSW?

  Food waste, thin plastics, papers, etc.
• What is required for the composting process to take place?

  Organic matter, suitable microorganisms, nutrients
• What are the two types of conditions for composting?

  Aerobic and anaerobic conditions
• What does aerobic decomposition produce?

  New cells, CO2, H2O, NH3, SO4-, heat
• What is produced during anaerobic decomposition?

  New cells, CO2, CH4, NH3, H2S, heat
• What is the ideal particle size for composting?

  1. 25 – 7.5 cm
• Why is moisture content important in composting?

  Required for microorganisms to assimilate nutrients
• What is the ideal moisture content range for composting?

  40 – 65%
• How does temperature affect composting?

  Different microorganisms require different temperature ranges
• What nutrient ratio dominates microbial activity in composting?

  C : N ratio
• What happens if the C : N ratio is too high?

  Slows rate of aerobic decomposition
• What is the acceptable range for C : N ratio?

  20 – 25
• What pH level is ideal for microbial activity in composting?

  1. 5 – 7.5
• How long does the composting process typically take?

  6 months to 4 years
• What factors affect the time required for composting?

  Waste composition and curing process
• What are the steps in the pre-processing stage of composting?

  1. Separate compostable materials
  2. Size reduction of the waste
  3. Sorting can be manual or mechanical
  4. Ensure waste size allows for aeration
• What are the methods of composting?

  1. Windrow composting
  2. Aerated Static Pile Composting
  3. In-vessel composting systems
• What are the issues and benefits of composting?

  Issues:

  • Pathogens
  • Bad odour
  • Cost economics
  • Heavy metal toxicity

  
  

  Benefits:

  • Savings on soil amendments
  • Revenues from selling compost
  • Job creation
  • Knowledge generation