Plastics? Get ready to mix it up with a PRF
The PRF - plastic reclamation facility - is set to become a cornerstone of our future recycling landscape as demand and value for used mixed plastics rises. Maxine Perella finds out more
As the momentum around mixed plastics recycling gains ground, it is now “giving food waste a run for its money in terms of interest” according to London Remade chief executive Daniel Silverstone. For this reason, his organisation decided to focus on the issue at its recent local authority network meeting held in London.
According to estimates from the British Plastics Federation, over 5M tonnes of plastics is produced in the UK every year, but only 19% is currently being recovered or recycled. However this is set to change as its value increases, and WRAP’s special advisor on plastics Paul Davidson told delegates that work was being undertaken to set up large-scale reprocessing trials, to see how mixed plastics can fit into the current MRF landscape.
The rise of the PRF
One way is to build dedicated plastics reclamation facilities (known as PRFs). PRFs will take in a mixed stream of plastics and separate them out into the different polymer types, before they are sent onto a reprocessor. If materials are co-mingled, the MRF can act as a pre-sort stage, but if plastics are kerbside-segregated they can effectively skip the MRF.
“Because the PRFs are doing the separation, the MRFs don’t have to so it lessens the burden on existing infrastructure,” explained Davidson, adding that bring banks and retail take-back routes can also segregate out mixed plastics and deliver them straight to a PRF.
He added that confidence needed to be increased in mixed plastics technology to demonstrate that PRFs would be a robust and sound investment option. “We need to do more work on the film fraction of mixed plastics to extract better value from it. We want to tighten up the economic modelling around the processes as well.”
The first pilot PRF could come on board in the capital as early as 2010, with Veolia expressing a strong interest in working with WRAP and other key stakeholders such as Defra to fund such a facility.
According to Veolia’s UK managing director Paul Levett, the first one “will be a relatively risky investment”, but he sees PRFs as being a key element of the future recycling landscape.
“It’s something we are very positive about developing in the not-too-distant future. We already get some mixed plastics through that aren’t meant to be there. They are contaminants and end up in the residue stream coming out of our MRFs. In the short term we will probably look at some form of solid recovered fuel to deal with those and use them as energy production,” he told delegates.
WRAP is also due shortly to start working with the packaging industry on R&D around pack design to increase the recyclability of more challenging materials, such as where dissimilar polymers are used together to create better barrier and heat sealing properties for packaging. “There must be better technologies and better ways of getting this functionality, but retaining the recyclability of the pack,” asserted Davidson.
A closer look at the capability of different technologies to deal with mixed plastics was offered by Rob Dvorak, project manager at Nextek – the company who developed and supplied PET and HDPE plant to Closed Loop Recycling’s food grade plastic bottle recycling pant in Dagenham, Essex, which opened earlier this year.
Dvorak firstly outlined demand for the different polymer types. “The polymers best for recycling are single polymers like PET, polypropylene or polyethylene. But there are very few markets for recycled polypropylene. Polystyrene and PVC are also being increasingly viewed as non-environmentally friendly materials, not in demand by major retailers,” he said.
In the domestic waste stream, 53.3% of plastics packaging is rigid, such as tubs; 30% is flexible such as film and chip packets; and 16.5% is non-packaging plastics and residual waste. In separating films from the rigids, Dvorak said there were systems out there that could address this with typical removal efficiencies of between 90-95%.
“Films are very light, most MRFs don’t want them flying around everywhere … you can bale the films and there are a number of film recycling plants in Europe which can reprocess them,” he told delegates. He added that dry cleaning systems were also available for cleaning up food-contaminated plastics, as well as glues and labels.
Demand varies according to polymer
Dvorak also advocated the use of pyrolysis for converting polyolefins into liquid fuel. While incinerating plastics is considered by some to be an inefficient way of generating electricity as it has a heavy carbon impact, pyrolysis is an alternative thermal treatment option which is done under a nitrogen blanket, with no oxygen or combustion aspect.
Maxine Perella is editor of LAWR