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for crops is high. There are many factors to be considered when calculating the total environmental cost of supplying this ‘renewable resource’.
No second life Is renewable the right description for this type of product? Surely this is a oncethrough system? Crops are grown as a feedstock, harvested as a chemical resource, put through an industrial process and at the end of their life are degraded to greenhouse gas (carbon dioxide) and water. There is no re-use, no second life for these products, certainly no recovery of the energy used to make them. Who amongst us feels this type of process is the way forward? Can we afford to waste this or, for that matter, any other resource? The term renewable resource should be replaced by the term repeatable resource as crops can be re-sown.
The case against biodegradation?
A
ccording to Petcore – PET containers recycling Europe – writing in PETplanet magazine, ‘biodegradation’, as a word is very confusing to non-experts. The dictionary defines biodegradation as the process of being broken down by bacteria. Members of the public will tell you that plastics don’t biodegrade and they will tell you plastics stay in the environment for years, as though this were a bad thing. It is acknowledged that plastics need to be fit for purpose and have a required service lifetime. In the view of many however, if plastics biodegrade, break down or ‘disappear’ they would be more environmentally friendly materials. Do they expect them to degrade as soon as they hit the ground?
What is the full environmental cost of ‘true’ biodegradable plastics? These are the plastics that are based on food crops such as corn. In this process industrialists extract the organic carbon from plants grown using modern agricultural techniques. It is this long and convoluted process that many claim to be environmentally friendly. The biopolymer industry uses phenomenal amounts of energy. The energy drain starts with the manufacture of tractors, seed drills, fertiliser spreaders, harvesting and drying equipment. It uses energy from fossil fuels and electricity. In addition, the water footprint
Perhaps an even more confusing use of the word biodegradation is the peculiar case of forced biological action. Here specific chemicals (additives) are mixed with conventional polymers in such a way that microbes can break down the additive in the plastic, weakening the polymer matrix and resulting in very, very fine but pure polymer particles. This is another waste of materials. Whilst we need technological understanding and technical expertise, all conventional polymers can be recycled over and over again - they are a truly renewable resource. However, the use of ‘eco friendly’, biodegradable additives produces many noneco-friendly problems. It takes a truly renewable resource, a conventional polymer, and renders it completely nonrenewable by breaking it down into a form that cannot be recovered, even using the very high level of development skills
demonstrated by the plastics recycling industry. Biodegradable additives in plastics packaging, especially PET, have been recognised as a major concern for the recycling industry. Claims from manufacturers that their additives have no effect on PET recycling are not backed by publication of any scientific evidence that this is so. In particular there has been no approach to the EPBP (the European PET Bottle Platform) or APR (Association of Postconsumer Plastics Recycling) so that these types of additives can be fully evaluated and approved by those with an interest in
rPET can be used for all virgin PET applications including many that stress durability and physical performance the recycling of PET. Indeed, APR has published its serious concern about this type of technology and the impact of such additives on the recycling process. As well as other outlets, rPET can be used for all virgin PET applications including many that stress durability and physical performance. Buyers of rPET want not only the sustainability features of recycled material, but assurance of performance. Degradable additives that weaken products or shorten the useful life of PET will have a negative impact on post-consumer PET recycling. As we have reported before, in 2008 46% of all PET containers were collected for recycle in Europe, a great track record we feel sure will continue. This sustainability must not be sacrificed on the altar of biodegradation.
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www.foodbev.com/water Issue 64 - January · February 2011
SPECIAL REPORT 33