Oxo-biodegradables come under fire again

By Paul Gander

- Last updated on GMT

Auras: 'No enhanced biodegradation'
Auras: 'No enhanced biodegradation'

Related tags: Anaerobic digestion, Polymer

New research from Michigan State University (MSU) has reignited the heated debate between advocates of compostable and oxo-biodegradable plastics.

The debate concluded that the additives designed to trigger polymer breakdown are “not recommended”​ for use where those materials are destined for anaerobic or aerobic biodegradation.

The peer-reviewed paper from the US university was published in Environmental Science and Technology. It tested polyethylene (PE) and polyethylene terephthalate (PET) films with three different oxo-biodegradation additives, including d2w from UK firm Symphony Environmental. Five polymer/additive combinations were each tested in compost, anaerobic digestion (AD) and soil burial.

No evidence

Rafael Auras is associate professor at MSU’s School of Packaging, and one of two lead authors of the paper, titled ‘Evaluation of biodegradation-promoting additives for plastics’.

He said: “There was no evidence that the tested additives promote or enhance biodegradation of PE and PET polymers. Anaerobic and aerobic biodegradation are not recommended as feasible disposal routes for non-biodegradable plastics containing any of the tested additives.”

In a statement, the Oxo-biodegradable Plastics Association (OPA) said it was “amazed”​ by the research. Technical director at Symphony Michael Stephens argued that the types of test carried out by MSU were inappropriate for the additive. “We don’t claim it will work in AD or in composting,” ​he said. “The main virtue of our material is in the percentage of plastics waste that is not put into AD, for example.”

Waste problems

Asked whether oxo-biodegradables excluded themselves, as a consequence, from a strengthening compostable waste stream in Europe, he stated: “We shouldn’t judge a technology based on the Netherlands or Germany, for instance, where they have good waste segregation.”​ Developing economies could not solve their waste problems that way, he argued.

Symphony was particularly critical of MSU because the company claimed early on to have offered advice on the types of tests it said were appropriate.

Related topics: Packaging materials

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