Upcycling: Cranfield team recreates value in landfill plastics via thermal process

21 Sep 2018 --- Cranfield University is mining landfill sites in the UK for previously discarded plastics and applying an advanced thermal treatment process in order to produce base chemicals for use in manufacturing or as liquid fuels. There are over 20,000 landfill sites across the UK and enhanced landfill mining is an emerging area that aims to recover value from such excavated solid waste, a process known as “upcycling.”

Plastics within closed household waste landfill sites account for around 15-20 percent of the total waste, according to the Cranfield tream. However, the value and viability of reclaimed plastics is not clear as it is typically low-grade and difficult to recycle economically.

Previous work at Cranfield highlighted that plastic recovered from landfill is not typically suitable for conventional recycling routes. Work is now underway to apply pyrolysis, an advanced thermal treatment process, to produce base chemicals for use in manufacturing or as liquid fuels.

The concept of enhanced landfill mining is promoted through the European Enhanced Landfill Mining Consortium, (EURELCO), of which Cranfield is a founding member. Maximum value is sought through excavating the waste, recovering value from materials (e.g. rare earth elements, secondary raw materials) and energy-rich commodities (plastic, textiles, paper and card) and by being able to use the resulting land space for further development.

Understanding the potential for secondary raw material recovery was explored in a recent project funded by the European Union under the Horizon 2020 programme (Smart Ground). The use of plastics for direct energy conversion is one option, however, work at Cranfield is seeking to develop more valuable products which would have a greater impact by substituting the use of fuels and chemicals derived from crude oil.

Dr Stuart Wagland, Senior Lecturer in Energy & Environmental Chemistry at Cranfield tells PackagingInsights: [Through the pyrolysis process] we can create base chemicals which could be used as raw materials in manufacturing processes. Packaging could be one of the end products.”

“We already see energy being produced from wastes containing plastics through incineration. Production of chemicals and transport fuels from waste is an emerging topic. Some pyrolysis and gasification processes currently have end-of-waste certification for the gases produced, thus these gases are considered to be a ‘product’ rather than a waste.”

“Estimating a timescale for wider commercialization is difficult, but I would anticipate further progress in this space within the next five years,” he says.

Wagland identifies cost as the biggest barrier the industry would need to overcome in order to adopt the pyrolysis process widescale.

“In this project, we are looking at upcycling plastics into base compounds for manufacturing, or for liquid fuels to substitute fuels produced directly from crude oil.”

“There are a number of potential advantages in recovering materials from closed landfill sites. These sites are a long-term environmental burden, requiring careful monitoring and management, with evidence showing that nearby groundwater can be affected. Enhanced landfill mining will effectively reduce this burden, recover valuable materials and enable the use of land for redevelopment,” he concludes.

By Joshua Poole