decay

• decomposition can produce compost
• compost is decomposed organic matter
• What is rate of decay affected by?

  temperature

  oxygen availability

  water availability

  number of decay organisms
• Biogas is made by anaerobic decay of waste material
• biogas is mainly made up of methane which can be burned as fuel
• decaying anaerobically produces methane gas
• biogas is made in a simple fermenter called a digester or generator
• biogas generators need to be kept at a constant temperature to keep microorganisms from respiring away
• batch generators make biogas in small batches
• continous generators make biogas all the time