Summer Stories Series: Biodegradable DebatablePosted on September 29, 2012 by DrRossH in Plastic Waste News
The author sort of go this right but got confused on the technicalities. Biodegradable does not refer to a rate at which a product biodegrades. It just tells you if it can be broken down by biological organisms or not. There is no time factor involved.
In the same sentence he got biodegradable and degradable confused. He was correct about the non recyclability of degradable products due to the possible compromise of the next product. Degradable is a chemical reaction and is on going all the time, whether the item is sitting on a shelf, on the ground. It needs oxygen to occur so if a degradable item is sent to a landfill the chemical reaction essentially stops and the item no longer breaks down. So you have to question the point of adding the degradable additive in it in the first place.
What he did not distinguish between was compostable-biodegradable and landfill-biodegradable. His reference to the plastic cups with the green stripe belonging in the trash for now is correct. That is because these would have been made from a compostable plastic which can only biodegrade if the cup is disposed to a commercial compost facility where higher temperatures, moisture and a good oxygen flow are ensured. If the compostable plastic does not get those conditions, then it will not biodegrade either. Not in your backyard compost bin nor in a landfill. Since there are few to none commercial compost facilities around, the advertising of compostable biodegradation is really green washing at the moment as the author inferred. And yes compostable plastics cannot be recycled. So at the current time with no infra structure to support the collection of compostable plastics and transport to a commercial compost facility, they have to go to a landfill where they will not biodegrade.
Landfill biodegradable plastics was what the author did not address. These are conventional plastics but with an organic additive in them that attracts microorganisms to digest the additive and the plastic molecules away. These additives are relatively new, only a few years old. A landfill biodegradable plastic will behave like a normal plastic till it is disposed to a landfill. It is not a chemical reaction, but a biological process that only starts once the plastic is in a landfill. A landfill biodegradable plastic has an indefinite shelf just like a conventional plastic. It can be recycled in mainstream plastics too as they do not affect the downstream product until they were to be disposed to a landfill. This is where we should be headed after we have done as much as we can to eliminate the manufacture of disposable plastic items. Those that are still necessary ought to be made with a landfill biodegradable additive in them. The 6% of plastic that gets recycled can still be safely done so, but the 94% of plastic that goes to a landfill will then biodegrade away.