Anthony Andrady says plastics in ocean biodegrade slowly

Anthony Andrady: Plastics have been around for less than 100 years. So in the short time span, there has not been a group of microorganisms who have evolved who are capable of biodegrading plastics.

Anthony Andrady is a plastics researcher at RTI International, which offers research and technical expertise to governments and businesses. Dr. Andrady pointed out that traditional plastics, such as those in food containers and water bottles, are a new material in the ecosystem of the whole Earth.

Anthony Andrady: This is my concern, we are placing all these plastics in the ocean, and eventually they will reach the deep ocean environment.

His special interest is the increasing quantity of plastic now known to be in the oceans. He said plastic lasts a long time there, because cold sea water slows down the chemical reactions that cause a plastic bottle lying on a beach to break down.

Anthony Andrady: If you define biodegradation as the complete conversion of plastics into carbon dioxide and water, all the plastics that we ever put into the ocean – which is over the past 50 to 60 years – would still be there in the ocean. And we keep adding more and more to it. And we do not know what the ecological consequences of this are. They might be very serious.

Andrady said government incentives are needed if plastic recycling is to become more sustainable. Meanwhile, plastics in landfills also biodegrade only slowly.

Anthony Andrady: It does not see much oxygen because the depth of the landfill is a very anoxic environment, so it does not biodegrade – it’s like a large tomb where we save all these plastics for posterity.

Andrady said there’s another type of recycling that should be encouraged:

Anthony Andrady: And that is use of plastics to generate the raw material that went into making it. This is called pyrolysis. We take the plastics and heat it at very high temperatures in the absence of oxygen and you chemically break it down to valuable raw materials. Some of it can be used directly as fuel: gasoline. This has a lot of potential but not been promoted as well as it should be, I think.

January 11, 2010

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