UCL’s Big Compost Experiment

University College London has published findings from their Big Compost Experiment – Using citizen science to assess the impact and effectiveness of biodegradable and compostable plastics in UK home composting.

You can read UCL’s research report here and their policy briefing here.

The Biobased and Biodegradable Industries Association (BBIA) has responded to the study, their press release including the following:

‘BBIA represents UK producers of compostable plastics, an industry that is a relative newcomer to the world of packaging materials. Whilst we have mature businesses operating here, we are also still on a steep technological learning curve and always welcome the opportunity of improving our materials and infrastructure to maximise ecological benefits.

Further background analysis on the UCL study, which BBIA members participated in, is below:

(a)    Home composting is by its very nature a variable process. There are various types of home composting unit; the mix of garden and any kitchen-source organic waste added will differ, as will local geography, weather and moisture content as well as the level of experience of the gardeners themselves.

(b)    The report itself confirmed that only 40% of the packaging items added by householders actually carried a claim of home-compostability and indeed 46% of the items added did not make any claim to any relevant standard whatsoever. As such, ‘perfect’ levels of compostability could never have been achieved.

(c)    Independently certified home-compostable materials do compost: Given the varied source of the packaging items added into the home-compost units, it is actually quite impressive that 45% of all items tried out had either completely disintegrated or broken down to less than 2mm and a further 31% showed significant levels of degradation. Only 24% of items failed to show any notable break-down, most likely those which made no claim to be compostable in the first place!

(d)    The report itself states that compostable materials play an important role; they facilitate the reduction of conventional plastic waste that leaks through food waste treatment systems to soil. According to the Environment Agency a variety of sources are inadvertently spreading some 100KT of conventional persistent plastics to soil in the UK annually.  Using compostables in applications that on disposal are likely to be co-treated with food waste will dramatically reduce that pollution.

(e)    Consumers are not professional waste management experts. The BBIA both fully supports and indeed is actively engaged in delivering better and more consistent labelling of compostable products. We also call for an end to any unclear or unsubstantiated on-pack terminology such as ‘degradable’ or ‘biodegradable’ that may confuse them. The BBIA is clear, however, that appropriate independently certified and marketed compostable packaging is not greenwashing.

(f)     Home composting is welcome, and we encourage it, but we also recognise that only a small part of the public can take part. In order to treat food and garden waste professionally we need collection systems and industrial composting along with anaerobic digestion to producer bio-fertilisers, soil-improvers and biogas and ensure treatment is carried out according to the highest environmental standards. Already in the UK 24 large scale composting facilities actively collect and process compostable packaging materials.

(g)    Compostable materials (bags, caddy liners and so on…)  play a crucial role in maximising the collection of such waste ensuring less contamination from plastics and pollution to soil. Such systems are growing across the globe from Korea to California, Italy to Denmark, Austria to Spain.  Here in the UK we need further investments in and technological development of organic waste treatment plants to ensure maximum recovery both of the food and garden waste we all produce, and the compostable packaging we receive, to produce the most beneficial outcomes for our society and national economy.’


REA’s further comments

An important part of UCL’s Big Compost Experiment results shows that participants have tried home composting independently certified home compostable items but also other items whose suitability is questionable as well as others that are clearly unsuitable.  For example, they have tried to home compost items just labelled ‘compostable’ (which might only be industrially compostable), ‘biodegradable’ (which might not be home and/or industrially compostable) and ‘degradable’ (not compostable at home or at industrial scale).

Clear labelling of items designed to be home composted and/or industrially composted is essential, not just for people who home compost these items but also for everyone’s understanding of which bin to place them in and for operators of industrial composting facilities who receive them.

Any organisation that has placed industrially compostable and/or home compostable items on the market but just labelled them ‘biodegradable’, ‘degradable’ or used a similar vague term must review their labelling, ensure it complies with the Green Claims code and meet the UK organics recycling industry’s item labelling needs.

Further, for any item disposed into a food waste bin for kerbside collection, REAL’s Compost Certification Scheme requires that such items are independently certified compliant with at least one of the following standards for packaging and non-packaging items’ suitability for organic recycling at industrial scale: BS EN 13432, BS EN 14995 or ASTM D6400.  This also applies to kitchen caddy liners, food bin liners, any bags repurposed for these uses and any bags or sacks used for containing garden wastes.

In addition, waste permit rules together with Environment Agency guidance on permit compliance require that any packaging or non-packaging item fed into an AD or composting facility in England must be independently certified compliant with at least one of the following standards or TÜV Austria’s named scheme below:

– BS EN 13432, BS EN 14995, ASTM D6400 (suitability for industrial scale organic recycling)

– EN 17427, AS 5810-2010, NF T51-800 (suitability for home composting), or

– TÜV Austria’s ‘OK compost HOME’ certification scheme criteria (suitability for home composting).

Considering other items on the market that are SOLELY designed to disintegrate and biodegrade in an open/natural environment – i.e. not a home composter, an industrial composting process or an industrial anaerobic digestion process – their labelling must comply with Green Claims Code requirements.   The UK’s organics recycling industry does not want them and they are not appropriate for home composting.