Michael Stephen Column

Disposal in the Right Way and Defra Consultation Responses (FREE)

Michael Stephen, an international expert on bioplastics, shares his thoughts and opinion on important issues impacting the bioplastics industry. Today, Michael writes about disposal in the right way and the Defra Consultation Responses. This is a FREE article.

Reading through the responses to the DEFRA consultation, there is one point which arises time and time again – it is that biodegradable plastic must be disposed of “in the right way.”

This is true for plastics marketed as “compostable” because they are tested according to EN13432 and ASTM D6400 to biodegrade in the special conditions found in a composting facility, where they are required by those standards to convert into CO2 gas within 180 days. Compostability is therefore a waste-management option, but not a very useful one, because these plastics do not convert into compost, and cannot be recycled. This process cannot therefore be regarded as recycling or recovery, and is not circular.  In any event, the composters and AD operators do not want plastic of any kind in their facility. See Composting  

By contrast oxo-biodegradable plastic is designed to biodegrade if it is NOT disposed of in the right way, and escapes into the open environment.  It needs only oxygen and bacteria – which are found almost everywhere.  It can be re-used, recycled, landfilled, or incinerated for energy-recovery just like ordinary plastic if it gets collected, but if it does not get collected it will safely biodegrade and be removed from the environment by the bacteria, much more quickly than ordinary plastic.

Defra Consultation Responses

I have continued reading through the 134 documents which DEFRA (the UK Environment ministry) refused to disclose to me until they were ordered to do so by the Information Commissioner. These are responses which DEFRA received to their “Call for Evidence on Standards for Bio-based, Biodegradable and Compostable Plastics.”  DEFRA have still failed to disclose five of these responses and I have appealed to the Information Commissioner in respect of them.  It is essential to know whether the government is being misled. 

Readers of this column will recall that DEFRA said in their response to the consultation that “There was a clear consensus in relation to plastics containing prodegradant agents aimed at aiding the biodegradation process, which was that such technologies are unproven and likely to be a source of microplastic pollution.”  (Readers will also recall that the European Chemicals Agency were NOT convinced that microplastics were formed).

I have still not found any such consensus.  In fact, most of the submissions give no evidence at all in response to Question 11 on “plastics containing prodegradant agents” but there is much more of a consensus for banning bio-based plastics – especially of the type marketed as “compostable.”  Perhaps this is why DEFRA did not want me to see them.  Further reasons given in the submissions (in addition to the ones published in my 6th December column) include the following:

“Regarding biodegradable bio-based plastics, composting does not pose a more suitable end of life compared to recycling or waste to energy treatment because the value of the product is lost.”

Q. What unintended consequences could arise as a result of a growth in use of bio-based plastics?  “There are many. Reduction in arable land usable for crops. Decrease in properties of plastics and thus increase in food waste. Decrease in food safety standards. Requirement to use GMO resources to efficiently produce plastic from bio-sourced products. Environmental cost of functionalising plastics to meet consumer /industry needs.”

There is also huge uncertainty on how demand for bio-based plastic feedstocks might affect food prices and land-use change and consequently GHG emissions and other environmental impacts.

Although there are considerable evidence gaps on bio-based plastics, based on the available evidence, producing bio-based plastics from crops does not result in significant environmental benefits and could lead to more environmental harm due to land-use change.

“There is also the issue that bio-based plastics can cause contamination in the dry mixed recyclable stream as it could be confused with fossil-based plastic.” [Leeds]

“Bio-based plastics damage recycling – the classic example of this is PET and PLA, where both of these contain an ester group within the plastic. These specific chemical bonds vibrate in a unique way, but their signatures are similar so they get sorted together. As the two materials do not blend well together, when they are mechanically processed and thermally reformed, this creates defects in the material and the recycled plastic is no longer fit for purpose. They become pollutants.”

“There is robust evidence of the footprint of conventional petroleum-derived plastics: these are some of the most efficient chemical processes on earth, and indeed help circularise the fuel industry by taking wastes from these processes to build useful products that retain value. Indeed, the efficiency of these processes and their low environmental footprint is why these materials are so inexpensive and have thus proliferated across the globe.” 

“Scale-up of bio-based processes is challenging because of the yield of these systems – they are inherently inefficient processes due to the discarding of the cellular matrix supporting the production of the target material. Waste must then be energetically transformed or incinerated, further contributing to emissions. Unless you are dealing with a large-scale feedstock (cellulose, lignin), the specialised supply is not available to meet the demand even of a small sector of the plastics market. But the biggest issue is the fact that we do not consider arable land to be a finite resource: It is. We do not have the land needed to grow our food, let alone our plastic.”

Aside from the risk of contamination for the conventional recycling stream, other unintended consequences might arise such as potential increase in greenhouse gas emissions from land use change as a result of growing feedstock from crops and other potential environmental impacts related to agricultural input (deforestation, loss of biodiversity, soil carbon depletion).

Landfill: “As the plastics are buried, this requires anaerobic degradation – and will be significantly more damaging that using petroleum derived plastics. The anaerobic degradation will favour methane generation, a much more powerful greenhouse gas, and further damage our environment.”

“Industrial composting is ……. an inefficient method of recovering value. If the effort is being made to capture biodegradable plastic waste, then this material should be depolymerised/catalytically recycled to create value instead of being transformed into greenhouse gases.”

“Home composting needs to be carefully managed, with a high quantity of wet food waste required to ensure complete degradation and avoid microplastic formation. As this is difficult to monitor at home, it is my view that this composting solution creates dangers.”

“When products are marked as ‘compostable’ residents often think that these can go in the home compost bin or garden waste recycling collection at kerbside, when in fact these are only suitable for industrial processing.”

“We have tested claims made by commercial organisations of their degradability and we have found none that degrade significantly outside of a curated environment of an industrial composter.”

“the Council have had quite a few residents contact us asking for help in disposing of items marked or certified as being ‘compostable. They are often confused and disappointed to learn that these items can’t be home composted, can’t be placed in garden waste collections, and can’t be recycled.”

“the Council’s garden waste recycling contractor has to screen the loads of waste that come in before treatment and remove all contamination, including any biodegradable plastics.”

“it may seem plausible to put items labelled biodegradable into food waste or into recycling. However, most are rejected because anaerobic digesters are not optimised for them. Instead they are burnt, or put into landfill. If they are put into recycling, they contaminate it and reduce the value of the recycled plastics produced.”

“PLA (biodegradable plastic) lined cups were more damaging to the machines than PE lined paper cups. The paper mill machines can tolerate only a small amount of plastic contamination.”

“bio-based polymers do not necessarily outperform fossil-fuel polymers – because of potential negative impacts from land and other agricultural input use. For example, an increase in greenhouse gas (GHG) emissions is associated with a hypothetical target of 5% bio-based polymer consumption at global scale (relative to current plastic consumption).”

“There are potential detrimental effects on food packaging safety.”

“If bio-based plastic were encouraged to be processed through composting, … you would definitely see an increase of fossil-based plastics causing more overall contamination and more going to landfill and a greater risk of plastics / toxins causing potential risk to the environment.”

“Bio-based products will still be released into the environment, for example through littering, and they will not degrade for a long time. In order to degrade, bio-based plastics must go through industrial processes.”

“It is not clear how bioplastics would help reduce avoidable plastic waste or the impact on both the existing infrastructure that deals with this material and also in terms of confusing the public about how materials can and should be disposed of.”

“The main potential consequences of bio-based biodegradable plastics are impacts on the quality of recyclate and the generation of pollution if they are put in the wrong waste stream. Growth of bio-based biodegradable plastics could increase littering and generation of microplastics.”

“The potential impacts of the growth of biodegradable plastics would be the increases of contaminates. Compost biodegrading process creates a sticky oversize, if fragments of biodegradable plastics are still present you would be reluctant to reuse the oversize and put it back through with another batch formation. This means the contaminated oversize would then most likely only be fit for landfill. The oversize would therefore become a waste product rather than a product you can use.”

Michael Stephen

Michael Stephen is a lawyer and was a member of the United Kingdom Parliament, where he served on the Environment Select Committee. When he left Parliament Symphony Environmental Technologies Plc. attracted his attention because of his interest in the environment. He is now Deputy Chairman of Symphony, which is listed on the AIM market of the London Stock Exchange, and is the founder and Chairman of the Oxo-biodegradable Plastics Association.

Earlier Postings in this Column

Interview with Michael Stephen


The opinions expressed here by Michael Stephen and other columnists are their own, not those of Bioplasticsnews.com.

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