This deep dive covers Composting and Biogas within Decomposition for GCSE Biology. Topic 4: Decomposition It is section 5 of 12 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
♻️ Composting and Biogas
Compost heaps use the same decomposition process to recycle garden and kitchen waste into nutrient-rich compost. To maximise decomposition rate in a compost heap, gardeners:
- Turn the heap regularly — introduces oxygen, maintaining aerobic conditions for faster decomposition
- Add water if dry — maintains moisture for enzyme activity
- Shred large items — increases surface area for enzyme contact
- Insulate the heap — retains heat generated by decomposer metabolism, keeping temperatures near the enzyme optimum
Biogas generators use anaerobic decomposition to produce a mixture of gases (mainly methane, CH₄, and carbon dioxide, CO₂) from organic waste material. The biogas can be burned as fuel for heating or electricity generation. Biogas generators are maintained under strictly anaerobic conditions because the methane-producing bacteria (methanogens) are obligate anaerobes — they only function in the absence of oxygen.
Practice questions for Decomposition
Which organisms are the main decomposers?
Explain how temperature affects the rate of decomposition.