decay

• what is compost?

  • decomposed organic matter used as natural fertiliser for crops and garden plants
• what is responsible for decay?

  • microorganisms like bacteria and fungi as well as detritus feeders
• how does temperature affect decay?

  • warmer temperatures make things decay quicker
  • increase the rate that the enzymes work at
  • really cold temperatures slow down the rate of decay too
• how does oxygen affect decay?

  • microorganisms involved in decay process need oxygen to respire, so they can survive
• how does water affect decay?

  • microorganisms involved need water to carry out biological processes
• how does the amount of microorganisms affect decay?

  • the more microorganisms there are the faster decay happens
• what is meant by decay?

  • the breakdown of dead materials into simple organic matter
• how does decay work?

  • the microorganisms involved in decay release enzymes which catalyse the breakdown of dead material into smaller molecules
• how many types of decay are there?

  • there are two types:
  • aerobic
  • anaerobic
• why can decay still occur in the absence of oxygen?

  • some microorganisms can anaerobically respire
  • but the rate of decay is slower as anaerobic respiration releases less energy
• how is biogas produced?

  • microorganisms anaerobically decay plant and animal waste which produces methane gas
  • methane gas mostly makes up biogas
• what is biogas made in?

  • biogas is made in a simple fermenter called a digester or generator
• why do biogas generators need to be kept at a constant temperature?

  • to keep the microorganisms from respiring away
• why can't biogas be stored as a liquid?

  • it needs too high of pressure
• what are the two types of biogas generators

  • batch generators
  • continuous generators
• what a batch generators?

  • they make biogas in small batches
  • they're manually loaded with waste
  • that are left to digest
  • by products are cleared away at the end
• what are continuous generators?

  • they make biogas all the time
  • waste is continuously fed in
  • so biogas is produced at a steady rate
  • they are more suited to large-scale biogas projects
• what do biogas generators need regardless of the type?

  • an inlet for waste material to be put in
  • an outlet for the digested material
  • an outlet so the biogas can be piped