WRAP report on plastics in composts and digestates

WRAP have published a report that looked at:

  • Evidence for the level of plastic contamination in UK (source-segregated) composts and digestates, and does any of this differentiate between compostable and non-compostable plastics.
  • How can plastics be measured in composts, digestates and soils, and how can compostable and non-compostable plastics be differentiated.
  • What process interventions are available to reduce the level of plastics in composts and digestates, how do they perform and what do they cost.
  • How are other countries tackling this issue. How do UK limits for plastics in compost and digestate compare. Is there any evidence that the levels of plastic found in UK (source-segregated) composts and digestates cause harm when applied to farmland.

You can access the report on the WRAP website here.

Key findings included:

  1. Data on compost and digestate contamination with plastics are rarely reported in published literature.
  2. Evidence indicates that certified compostable plastics will break down during composting processes, providing the process conditions align with those specified within the standard against which plastics are certified. Non-compostable plastics can be removed before or after composting to achieve PAS100 limits. Stakeholder feedback suggests that compliance with the lower Scottish limits is challenging, requiring a focus on litter-picking from feedstocks prior to composting.
  3. There are no data on the presence of compostable plastics in digestates.
  4. Screening of whole (liquid) digestates is used where necessary to ensure compliance with PAS110 limits. Stakeholder feedback suggests that compliance with the lower Scottish limits is achievable, albeit that this creates a greater quantity of plastic-contaminated screenings for onward processing / disposal.
  5. Although a number of harms have been demonstrated from plastics in soils, reliance on acute dosing of environmentally unrepresentative concentrations of plastics with short exposure times, combined with inconsistencies in reported impacts and complexities resulting from responses to different polymers, particle sizes and particle shapes means that it is not currently possible to suggest evidence-based limits for plastics in composts, digestates or soils.
  6. This project has highlighted an absence of strategic data to inform current and future policy relating to biowaste recycling and the need to reduce or eliminate environmental contamination with plastics. Addressing this deficit will require collaboration across policy, industry, regulatory and research communities.

The report also sets out a number of proposed actions, some of which REA will be involved in. For further info please contact [email protected].