This demonstration introduces students to the concept of biodegradation and the conditions that promote composting.
Biodegradation is the process by which organic substances are broken down by enzymes produced by living organisms. Biodegradation can be thought of as waste decaying or rotting.
Biodegradable matter is generally plant and animal matter and other substances originating from living organisms. Biodegradable human-made products ranging from paper bags to egg cartons.
In normal environmental conditions, rotting is affected by:
- Availability of air: Many bacteria and fungi need oxygen from the air in order to live and begin the decomposition process.
- Temperature: Decomposers need a certain temperature to live. Many biological reactions will speed up in warm temperatures and slow down in cold temperatures.
- Availability of water: Decomposers need water to survive and reproduce.
- Chemical composition of food: the higher the nitrogen to carbon ratio the quicker organic matter will rot because decomposers can get more energy from nitrogen. It’s important to note that both carbon and nitrogen are important for growth, however.
Landfills do not offer these conditions and therefore they cannot enable proper rotting. In fact, studies have found readable newspapers from the 1950’s in landfills, along with 25 year old grapes!
Average Time to Decompose:
|Vegetables||5 days - 1 month|
|Paper||2 - 5 months|
|Cotton T-shirt||6 months|
|Orange Peels||6 months|
|Tree leaves||1 year|
|Wool socks||1 - 5 years|
|Leather shoes||25 - 40 years|