Degradable, Biodegradable and Compostable, what does it all mean?

green | November 9th, 2009 - 11:38 AM

degrad

Do you sometimes wonder what on earth the terms degradable, biodegradable and compostable mean? Or what the actual difference between them is? It is easy to be confused when they are bandied about without accompanying explanation. Here we explain the difference between the three, giving people a greater understanding so they can take an informed purchasing decision.

Degradable is a broad term given to natural and human made substances that can be broken down by natural processes into smaller parts. Things can be photodegradable (broken down by ultraviolet light), oxidative (broken down by thermal exposure) or biodegradable (broken down by the action of microorganisms).

The term “degradable” in itself does not specify any time frame in which something will break down – for instance, a large tree trunk will biodegrade over the space of many years. A tin can is degradable too; it will break down over a long period of time through oxidation, and weathering. An EPI plastic bag (regular plastic that has been treated to make it degradable), will begin to degrade after about 12-18 months, and the time it takes will depend on how much light and stress (movement) it experiences.

Biodegradable is a term given to material that, as a result the of biological activity of microorganisms (bacteria, fungi and algi), breaks down completely into the raw materials of nature (CO2 , H2O, inorganic compounds and biomass) from which it was made, and disappears into the environment.

Compostable is a term given to biodegradable materials that biodegrade within in a certain time frame under typical composting conditions (which require heat and moisture; and are consistent with the composting conditions required for other known compostable materials like cellulose).

So when you are choosing what to buy, where ever possible, choose “compostable”, which is therefore also biodegradable; this should be your first choice. Second choice is biodegradable, although this does not necessarily mean it will be “compostable”.

And remember that everything is degradable (will fall apart into smaller pieces) eventually, even if it takes a century: this term does not actually tell us much about how long the material will linger in our environment or the effect the resultant “smaller pieces” might have.

thanks to Green Times: Is “degradable” biodegradable? by Lucinda Flynn


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One Response to “Degradable, Biodegradable and Compostable, what does it all mean?”

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