Why ‘everyone is blaming everyone else’ for plastic-contaminated soils

In England 600 tonnes of plastic fragments are spread to soils through digestate certified to PAS110 standards every year. Some 150 plastic bags’ worth are also permitted for every tonne of compost certified to PAS100.

Plastics make their way into soils. Photograph: Getty Images Plastics make their way into soils. Photograph: Getty Images

What this means for the environment (and where the plastic ends up) is poorly understood but the regulator has had enough. The Environment Agency wants to shrink the plastic coming from food and garden waste streams to almost nothing within five years. 

“We will require stricter wastes acceptance and assessment, and have placed limits in our standard rules permits that will require operators to tell us how well their technology is working,” a spokesperson tells ENDS. “We are also working to tighten the plastic limits on ‘end of waste’ [PAS] certified material, compost and digestate to land.”

Final guidance is expected “in the autumn”. An outcome report on revisions to the regulation of biowaste published in February noted that operators – including those with bespoke permits – will have to remove all plastic contamination to “as low as reasonably practicable” prior to treatment. There will also be year-on-year reductions above the current PAS100 and 110 limits, which the EA deems “unacceptable”.

In its document, the agency noted “a great deal of support” for the premise of the proposals on plastic, which generated more discussion than any other element of the consultation. The practicalities remain a concern however, with some experts claiming the organic recycling chain is “broken” and subject to a blame game.

Take the suggested 0.5% weight per weight (w/w) contamination limit on non-biodegradable plastic in the incoming waste, which was poo-pooed by 16 of the 25 respondents. Local authority contracts tend to allow for 5%, which is “absolutely appalling,” says David Tompkins, head of knowledge and innovation at consultancy Aqua Enviro. “There's no chance of getting that out and generating a quality output if local authorities think that’s acceptable.”

How much plastic is actually arriving in loads is moot. Research for the Scottish Environment Protection Agency (SEPA), published in April 2019, showed contamination of food waste across eight samples arriving at compost sites ranging from less than 0.1% to more than 1.3%. Achieving the new plastic limits – 50% of the PAS100 limit – the regulator had set for December 2019 would be “extremely difficult”, the authors noted.

The EA is keen to follow SEPA’s lead on those limits. By 2022 all operators taking contaminated feedstock “will be required to demonstrate adequate and efficient plastic removal prior to and during processing”. There will be site checks to ensure this is happening, the EA confirmed. 

Some anaerobic digestion (AD) plant operators in Scotland have put in place additional screening equipment. Others have tweaked their operations. Some composters have found it “difficult to comply with” admits Jenny Grant, head of organics and natural capital at The Association for Renewable Energy and Clean Technology (REA). “Hopefully the result is better quality outputs with less risk of contamination.” 

While this might be the case, there are suggestions that considerable amounts of organic matter are also being lost during the additional cleaning stages. Some 20% of the wet waste can be dragged out with the plastics. Each tonne of plastic or packaging with food waste stuck to it also costs £156 to manage, according to REA, which is supporting mandatory use of compostable bags.

A policy paper just published on the association’s website details how compostable liners certified to EN13432 can enhance food waste collections and “lead to lower plastic contamination”. More compostables mean less plastics, the argument goes, so expect the costs of providing the bags versus the savings made during treatment to be fiercely debated as the government’s 2023 target for mandatory food waste collections nears.

Plastic contamination is certainly a drain on profits. Based on surveys with its members, REA reckons contamination of biodegradable wastes is 1% w/w. If that’s the case, the UK organics recycling sector could be removing 78,080 tonnes of plastic, at a cost of £7.26m. Those estimates are based on 2014 figures. The tonnages of organic waste being recycled have increased, and will surge in 2023 – which is why the agency is so keen to address the issues “now”. 

The EA is working closely with recyclers, trade bodies, local authorities and DEFRA on this but the pace of progress is slow. Confidence in the output is on the wane, according to the NFU. The limits imposed by current waste input contracts (around 5%) are not sustainable, claims the union’s environment policy advisor Philippa Arnold. “Contamination should be reduced at every stage, wherever possible and not just passed on throughout the chain to the end user – the food producer,” she said.

Collaboration can be hard to find in this sector. “Everybody blames everybody else [for the problems],” Tompkins says, and that’s been the situation for the past decade. “The entire supply and recycling chain is kind of broken.”

The EA and DEFRA certainly have their work cut out. This is an industry that has grown on the back of contaminated material. The EA wants operators to turn away heavily contaminated loads (easier said than done) but has yet to explain how it expects sites to assess levels of contamination in feedstock. The 5% limit set out in many collection contracts is seen as the starting point but whether new contracts will include lower limits remains to be seen.

Indeed, preventing plastic contamination has long been seen as too complicated, not least because it starts with education. Councils argue they are hamstrung by ever-diminishing budgets. Splashing cash on a communications campaigns to help householders put the right things in their kitchen caddies has become a pipe dream. “Once contamination is introduced to waste streams, it is much more difficult to remove at later stages,” says Stuart Hayward-Higham, technical director at Suez.

Though the focus on the EA’s proposed changes focus on the material coming in, it has been critical about the standards for the output. A review of the limits set out in PAS100 and PAS110 (which cover 2m of the 2.7m tonnes of compost produced in the UK every year) is underway. The plan is to bring these in line with those in Scotland: 50% of the PAS100 limit for composts and 8% of the PAS110 limit for digestates. “We will also be assessing the amount of material spread to land,” EA’s spokesperson explains. 

But what constitutes an acceptable level of plastic to be spreading in these materials? The EA noted in its 2019 ‘The state of the environment: soil’ report that the impacts of plastic accumulating in the soil “are not well understood”. A study led by Anglia Ruskin University showed that earthworms lost weight when certain microplastics were present in the soil but the reasons for this “need unravelling”.

More research is needed on everything from contamination levels in collections to the impacts of these plastics on ecosystems but this doesn’t appear to be a priority for government-backed funding channels. The precautionary principle should therefore be applied, say experts. The industry needs to get behind a clear message, Tompkins explains, which is “zero plastic on land”. That would certainly be a simple message. Achieving it is likely to prove anything but.


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