Compostable food waste collection bags deliver biggest benefits, study finds
The Bio-based and Biodegradable Industries Association (BBIA) and associated member companies commissioned Sancroft International to undergo a detailed cost analysis of the implications of different food waste caddy liners.
The research was commissioned because of the mandate for all councils to offer separate domestic and businesses food waste collections in England post-2023 to help policymakers at a national and local level to understand which system is the most environmentally and economically beneficial.
Sancroft undertook a range of interviews with UK operators and stakeholders over the summer. The research looked at:
- The comparison in costs between using PE bags, compostable plastic bags, paper bags, and no bags
- The existing cost of extraction and disposal of non-compostable contamination from food waste treatment before digestion or composting
- Potential cost savings through sending separated bags and food waste to compost rather than burning separated plastic
- Benefits in terms of soil quality and contamination of food systems
- Benefits in yields and resource efficiency through encouraging households to segregate waste and reducing contaminated waste streams
Sancroft modelled the systems in a graphic which shows existing and future collections indicating how resources would flow differently in the two scenarios.
The model looked at what could vary within the policy preferred anaerobic digestion (AD) stream – assuming that the food waste sent to IVC with compostable bags already will continue to do so, this is not of concern in the study. The main concern is whether AD plants will face higher costs from moving away from plastics in food waste collections to compostables and whether those costs are justifiable in a resource-efficient future.
According to BBIA, the conclusions are clear: “The evidence shows that the most cost-effective option that delivers the biggest benefits for the nation is the use of compostable bags as a liner, as the most effective balance of reasonable costs, minimisation of plastic contaminants in the biodegradable waste stream, the maximisation of total food waste collected and processed.
“Based on that logic, the priority is first compostable bags, then paper bags, then lastly, no bags and PE bags, since both have significant downsides whether in plastics contamination or poor yields and high greenhouse gas emissions.”