8 November 2017 by Elizabeth Slow

Plastic liners backed for food waste caddies

Research carried out by the Food Waste Recycling Action Plan (FWRAP) Steering Group into food waste liners has suggested that polythene plastic liners are favoured by AD operators at “the current time”.

FWRAP is an industry-led plan, designed to improve the capture, supply and quality of household and commercial food waste. Its first annual report, published this week, looks at the progress made over the last year.

One of the achievements highlighted in the report is the publication of a linked ‘crucial’ report on ‘Industry Guidance: Dealing with Household Food Waste at AD facilities – Management of Liners’.


According to WRAP, this guidance will help AD operators to limit the amount of plastic, including bioplastics, which ends up in digestate as a result of food waste caddy liners.

In the guidance, WRAP suggests that polythene (polyethylene/PE) liners are favoured by operators of anaerobic digestion (AD) plants.

Anaerobic digestion

Anaerobic digestion: study finds PE liners are favoured at present (picture: Agrivert)

WRAP said that when householders use liners this is known to increase participation in food waste recycling, and local authorities are increasingly allowing householders to use plastic (PE) liners as opposed to more costly compostable liners. This poses a ‘challenge’ to AD operators who process that food waste, because liners in AD systems can causes operational and quality issues.


However, according to WRAP, research undertaken with AD operators has suggested that PE liners are the most favoured option at the current time, primarily due to the fact that they are easily removed at both the front end, and where required, from the back end of the processing system.

The organisation reports that several kinds of commercial biodegradable plastics are marketed as being able to degrade under anaerobic conditions, although in reality “most do not degrade quickly under these conditions.”

WRAP said unless bioplastics are rapidly soluble or dispersible, a form of pre-treatment such as shredding is required to make them suitable for processing by wet anaerobic digestion. The charity noted: “Otherwise, they may self-segregate by flotation or sedimentation then require removal and will not actually be digested, even if anaerobically digestible.”


In its report, WRAP said: “Huge progress has been made in creating evidence-based, practical industry guidance on dealing with contamination and the potential for accepting non-compostable liners at AD facilities.

“In the past year real progress has been made”

Ray Georgeson, chair
FWRAP Steering Group

“These two focus areas will help decrease contamination whilst at the same time improving participation rates by reducing costs and barrier to recycling for the householder.”

Over the last year FWRAP has also completed seven pilot studies assessing the business case for implementing separate food waste collections in seven partnership areas involving a total of 49 local authorities.

In his introduction to the report, Ray Georgeson, chair of the FWRAP Steering Group, said: “In the past year real progress has been made. Two particularly useful highlights have been the completion of the work on a Cost Benefit Analysis Tool and the new industry guidance designed to support AD operators in meeting the challenges of handling collected household waste.

“Both of these documents are free to download and they will serve as an enabler for local authorities and food waste operators to work through scenarios for identifying costs, savings and benefits from collecting more food waste. For me, they serve to illustrate the tenor of the work completed this year.”

Related links
FWRAP report


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