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Terminology Introduction
 
The terms biodegradable, degradable and compostable are used interchangeably, particularly when the media discusses packaging and carrier bags. Often you are led you to believe their meaning is the same but this is far from the truth. Each term has a distinct meaning and when it comes to waste management, particularly biowaste management, these meanings become essential as it will determine what the most appropriate method of recovery is. What exactly do these terms mean and how do you know which materials are suitable for your systems and processes?

Biodegradable
On its own the term biodegradable means very little as given time, almost everything is biodegradable. Unlike compostables (see below) there are no defined time limits or criteria as to what is acceptable for 'biodegradables' which makes it a very loose and potentially dangerous term. Depending on what they are made of and the thickness of the material, some products will biodegrade quickly whilst others might take many years to fully biodegrade. So when discussing whether or not a product is biodegradable it is imperative to identify the specific environment where biodegradation is intended to take place i.e. composting, anaerobic digestion, soil, marine or freshwater environments. The relevant international and European Union standards are geared to specific biodegradation environments (e.g. composting and anaerobic digestion), and set maximum timescales during which the material must sufficiently biodegrade. Additionally, requirements differ from one standard to the next. If a packaging or plastic material is described or labelled as simply 'biodegradable', this does not convey sufficient meaning about suitable ways to recover it after it has become waste.
 
Compostable

These are materials which biodegrade through the action of naturally occurring micro-organisms and do so to a high extent within a specified timeframe. These materials can be safely composted together with the organic fraction of municipal solid waste to produce compost. Compostable plastics do not hamper the composting process because they are biodegradable, disintegrable and do not affect the quality of the final compost. Compliance with the EU standard EN 13432 indicates that all these requirements are satisfied.

Further information about 'biopolymers'

http://www.wrap.org.uk/retail/materials/biopolymers.html

http://www.european-bioplastics.org/index.php?id=155

 

[Oxo-, Oxy-, OxoBio-] Degradable

These are materials which are based on polyethylene or polypropylene with a metal based additive and will, in an undefined timeframe, fragment to smaller particles when exposed to heat or ultra-violet light but are slow to biodegrade relative to 'compostable' plastics based on other renewable materials such as starch and cellulose. Degradable plastic is hydrophobic (has little or no affinity for water) and may attract other hydrophobic particles - including pesticides and heavy metals - which can lead to bioaccumulation of toxic substances. 'Fragmentable' is a less misleading way to describe these materials.

Up to now, no degradable plastic has managed to get certified as 'compostable' according to EU harmonized standards on biodegradability and compostability [link to next page] and thus are not suitable for composting processes, particularly those working to produce quality composts that meet the British Standards Institution's Publicly Available Specification for Composted Materials (PAS 100). This plastic is also unsuitable for recycling as the additive will remain in the recyclate making it unstable. WRAP have said that due to issues over recyclability and not meeting the European Standards for biodegradability and compostability, degradable plastic is not suitable for retail primary packaging. See WRAP's 'Biopolymer packaging in UK grocery market' briefing for further information andEuropean Bioplastics's position paper on "Degradable" PE Productsand anti-littering position.

The Green Claims Code

When making a specific claim regarding packaging in the UK,Defra's Green Claims Code's recommendations should be followed.

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Jul 22
 2017
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