What actually does Biodegradable and Compostable mean?

What is the difference between the terms Biodegradable, Compostable and Degradable?

The world of green, like any other industry, has its own language - for the person trying to make some environmentally changes to their life, it can get awfully confusing - take for instance the terms biodegradable, compostable and degradable when used in relation to plastics. There is a difference between the terms and it may play a role in your purchase decisions.

Biodegradable Plastics - BioPlastics

Biodegradable products break down through the action of a naturally occurring microorganism, such as bacteria, fungi etc. over a period of time. These products are usually made from plant or animal sources. Examples of biodegradable include paper, vegetable scraps and some forms of plastics made from ingredients such as corn starch.

Compostable

This is pretty close to biodegradable bioplastic but "greener". According to the American Society for Testing & Materials, for plastic to be considered as compostable, it must be able to break down into carbon dioxide, water and biomass at the same rate as paper. It also needs to look like compost, should not produce any toxic material and should be able to support plant life.

Compostable items are made from plant materials such as corn, potato, cellulose, soy and sugar. International standards of recognition for compostability can be certified with European Standard EN 13432 or the American Standard ASTM D6400.

Degradable Plastics – Photodegradable, Oxodegradable

Degradable plastics are petroleum based and break down through chemical reactions rather than the activity of micro-organisms, so they can degrade in an anaerobic environment/ light/ oxygen into water, CO2, biomass and trace elements. As degradable plastics are made from petroleum, they cannot be certified as green products as they cannot be broken down by microbes nor be composted.

So, a green packaging material should have the following certificates to verify its eco-friendly claims:

1) ISO 14001 – Environmental Management Standard

2) ISO 14855 – Determination of Aerobic Biodegradability

3) EN 13432 or ASTM D6400 – Standard Specification for Compostability