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Blog: Understanding the different biodegradable plastics

Date: 28/10/2013 | Author: Michael Laurier

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Symphony Environmental Technologies chief executive Michael Laurier explains why certain biodegradable plastics can be used in conventional recycling processes 

When considering the recycling of biodegradable plastic it is essential to distinguish between two very different technologies – bio-based and oxo-biodegradable.

Bio-based plastics or “bioplastics” cannot be recycled with oil-based plastics, because they contain an incompatible vegetable-based material, which would compromise a recycling scheme.  The same is true of plastics containing “enzymatic” additives.

There are other problems associated with bio-based plastics.  Although marketed as “compostable” they cannot be made into compost because the international standards (EN13432, ASTM D6400 etc) require them to convert to CO2 gas within 180 days, they can also generate methane in anaerobic conditions, they are much too expensive for everyday use, and the European Parliament has resolved on 11 September 2013 to discourage the use of land and water resources to produce bio-fuels.  The same reasoning applies to bio-plastics.

By contrast, oxo-biodegradable plastics do not suffer from any of these problems. They are 99.9 per cent ordinary plastic, together with a special masterbatch such as d2w, which turns it into a biodegradable material at the end of its useful life.  It does not just fragment, but ceases to be a plastic. However, before the end of its useful life it can be recycled with ordinary plastic without any need for separate collection.

It is sometimes asked whether the oxo-biodegradable formulation affects the quality of the recyclate, and this is a concern often expressed in relation to PET bottles.  It should therefore be understood at the outset that oxo-biodegradable masterbatches are not suitable for PET bottles and are not marketed for that application.

Some recyclers have published their concerns in the press, but they have never approached the Oxo-biodegradable Plastics Association for advice. In fact, there is an abundance of independent evidence that oxo-bio plastic can be successfully recycled in the conventional plastic waste stream, most recently the research carried out by Roediger laboratories at Stellenbosch, whose conclusion was: “We are able to confirm that plastic products made with d2w oxo-biodegradable technology may be recycled without any significant detriment to the newly formed recycled product.”

There is a detailed position paper on recycling, and another on “Enzymatic” additives, on the OPA website (www.biodeg.org).

All the oxo-biodegradable carrier bags collected for recycling by the Co-op and Tesco in the UK, were seamlessly incorporated into the conventional plastic waste stream, with causing any problems. Symphony Environmental, a founder member of the OPA, has offered to conduct trials with recyclers to confirm that they can safely include oxo-biodegradable plastics into their existing recycling stream. Symphony has also shown its confidence by offering the UK Government a guarantee that it will accept for recycling all the conventional and oxo-bio shopping bags collected in England if the Government exempts oxo-bio from its proposed levy on shopping bags.

Symphony has distributors for d2w oxo-biodegradable masterbatch in 92 countries around the world, and nine countries (with a combined population of 195 million people) have made it mandatory to use oxo-biodegradable technology in plastic products (not just bags).  They have done this because they know that some of the plastic waste will always get into the open environment where it would otherwise lie or float around for decades.

 

 

 

 


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