What does ‘biodegradable’ mean?

What does ‘biodegradable’ mean?

Posted on December 11, 2011 by DrRossH in Plastic Waste News

Picture of man made vs nature madeAs usual nothing in life is that simple.  Biodegradable does not mean compostable.   Many materials will biodegrade in a compost facility but many will not.   This should be well understood.  Most compostable material will NOT biodegrade in a landfill.  It persists there like a conventional plastic.

In a compost facility, when matter biodegrades it is converted to CO2.  Any energy that was contained in the matter is therefore lost.

In a landfill, when matter biodegrades, it produces methane.   This allows us to harness the energy out of the methane as we combust it and convert it to CO2.  A problem here is we can’t capture all the methane.  So some escapes to the atmosphere to do more damage than the CO2.  However methane is a very clean fuel and when it is burned for energy it is replacing other energy sources, perhaps coal which releases a lot of C02 to the atmosphere, so the net effect on the atmosphere has to look at both factors.

On just the environmental side, when a plastic item is disposed it will last many 100’s of years.  Is that the legacy we want to leave to the future generations?   We should not be leaving our problems for them.  So from that point of view, we should do all we can to eliminate plastic waste.   So reduce, then reuse then recycle, but then rejuvenate.   This is a phrase we coined earlier.   The rejuvenate is to make products biodegradable so that after reduce, reuse and recycle have been exhausted, then discard to a landfill or compost facility (if there is one around) and let the product biodegrade away.

Hence considering these arguments, making items having the ability to biodegrade is preferable.  Call it a backstop feature.  Build it into plastic products at the time of manufacture.  Consider the Reduce, Reuse and Recycle first, then if those don’t work let the product biodegrade away and return to the earth.   A complication on this is there compostable plastics are not recyclable, nor are oxo degradable plastics.  Many of these manufacturers will lead you to think they are but they are producing non recyclable products.  They have to go to compost piles or landfills.  Compostable plastic will not biodegrade in a landfill.  Oxodegradable plastics will not biodegrade at all.  Related Link