The definition of Biodegradable according to the Dictionary is: ‘(a substance or object that is) Capable of decaying through the action of living organisms.
So it basically means that the item will eventually, through time and a natural process (involving microorganisms, sunlight, water and oxygen) be broken down into natural components that do not cause any harm to the environment. For instance, a leaf that has fallen off a tree will biodegrade naturally without causing any harm to its natural environment. Mostly everything in nature is biodegradable. There are items that we use and consume every day that are biodegradable. For instance, fruit and vegetables and other food items. Also, natural paper, wood, cotton and other items mostly made from natural raw materials can be biodegradable.
Time.
Time is important for biodegradability, as it takes time for an item to fully biodegrade. The time it takes for an item to biodegrade depends on the item. Scientists use a respiromity test to determine the time it takes for items to biodegrade. The test involves inserting a tiny piece of the item into a container along with microorganisms (Bacteria) and soil, then expose it to oxygen and sunlight. They then measure the time it takes for the microorganisms to digest the item as well as the amount of Carbon Dioxide produced. This gives the scientists a measure of degradation.
The Science Learning Hub gives us an indication how long some common items will take to break down if left in the environment:
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
Plastic-coated paper milk cartons: 5 years
Leather shoes: 25–40 years
Nylon fabric: 30–40 years
Tin cans: 50–100 years
Aluminium cans: 80–100 years
Glass bottles: 1 million years
Styrofoam cup: 500 years to forever
Plastic bags: 500 years to forever
Landfills.
The above list gives an indication of the biodegrading time. This time frame assumes that the items are left to degrade in the natural environment. Which means the item had full access to soil, sunlight, air and the bacteria needed to biodegrade. However, things work very differently in landfills. The Garbage Project by William Rathje, professor of anthropology, and fellow archaeologists at the University of Arizona. They wished to study the effects of landfills on biodegrading items and what they found was very disturbing. “Perfectly preserved heads of lettuce, 40 year old hot dogs, and completely ledgible 50 year old newspapers.” What they concluded was that very little biodegration happens at landfills due to the lack of soil, sunlight, oxygen and microorganisms.
Plastic and non-biodegradables.
The problems with plastics, Styrofoam and other non-biodegrabable items are the fact that they take a very long time to break down. In the case with plastics, it usually first breaks down into microplastics which are worse for us and the environment. Which means that the plastic we use once then throw out today will be around long after we have gone. Are we as humans making good decisions by producing and using these plastics when most are only needed for a single use. For example, you buy a bottle of water from the store, drink the water and throw the bottle in the garbage. Does it make sense that the bottle will be around for 500 or more years when it was only the water that you really needed?
This is where reduce, reuse and recycle habits become very important. What can you do to help? Firstly, reduce the amount of plastic that you buy or stop buying plastic. Secondly reuse the plastic that you have bought. And thirdly recycle the plastic that has been used instead of throwing it into the garbage. Hopefully together we can decrease the demand for plastic and in time we will stop producing plastic altogether and find a more biodegradable options.
Little changes today. Big impact tomorrow.
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