Recycling: Sorting the plastics problem

The problem with getting consumers to recycle plastic is there’s no such thing as plastic. Or rather plastic is more than one thing. The large range of materials to suit individual requirements is, of course, one of the great strengths of polymers, as is the fact they can be sandwiched together for even more applications, but it’s a difficult message to convey to the consumer who has to separate them for the recycling bin.

More than a million tonnes of non-bottle plastic packaging enters the UK waste stream each year. Wrap has been at the forefront of developing plastics recycling in the UK and understands ‘mixed plastics’ as all non-bottle plastics packaging in the domestic waste stream. “We recognise the term ‘mixed plastics’ means different things to different people in the recycling and packaging industries, so we needed a consistent definition for our research,” says Paul Davidson, the Waste and Resources Action Programme’s (Wrap) plastics advisor. In part thanks to Wrap’s efforts, 80 local authorities, of the more than 450 in the UK, now collect yoghurt pots, ice-cream tubs and films of a range of colours and polymer types.

One problem, however, is the the remnants of food that can get stuck to the inside of the container to consider. Contamination, both from food and other polymers, is one of the reasons that energy-from-waste (EfW) facilities could be a good destination for some plastics waste. This process is widely considered as preferable to landfill and seems to be garnering support in the corridors of power. Philip Law, public and industrial affairs director at the British Plastics Federation (BPF), says the number of planning applications for EfW facilities is increasing. “The UK has been slow to recognise the value of energy from waste compared to other European countries. As a net importer of energy, EfW certainly has its attractions as a means of helping the deficit,” he says.

The value of recycling
EfW might be a good route for some plastic waste. But, as the BPF says, the best way to recover the value of the materials is through recycling. Environmental benefits aside, recycled plastics can be some 40% cheaper than virgin polymers, and research by Wrap has shown it is commercially feasible to collect and recycle mixed plastics, providing a factory is built to process at least 80,000 tonnes of material each year.

Improving plastics recycling rates is at the heart of the Plastics 2020 Challenge, launched by the BPF, together with Plastics Europe and the Packaging and Films Association, in July. “Not only are landfill sites filling up, but used plastics are too valuable a resource to be landfilled,” says Law. No one in the supply chain would dispute the scheme’s goals, but plastics charity Recoup has highlighted the importance of getting all stakeholders involved. “It will be interesting to see whether the Plastics 2020 Challenge can succeed in gaining enough multi-sector support to turn debates and discussions into tangible actions that deliver real results,” says Recoup’s business development director Stuart Foster.

The consumer is a key link in the chain and differences between local authority collections remain a hurdle to getting them to put different materials in the correct containers. On-pack information needs to reflect the recycling taking place on the consumer’s street, and having 450 different labels is clearly impossible. Recoup suggests that using polymer number codes (see box, right) would confuse rather than encourage recycling and says more work needs to be done in this field. “Ultimately, the information should be based solely on what the plastics reprocessors can accept, rather than what local authorities collect,” says Foster.

Chris Dow, managing director of Dagenham-based Closed Loop Recycling, which recycles PET and HDPE bottles, echoes this view. “It’s going to be a tough job to have complete consistency to collections, but having a lot of different systems doesn’t help anybody,” he says.

New frontier
Dow is keen to expand the range of materials he can process, but admits that each material presents a different challenge. “There’s no doubt the next exciting frontier will be other non-bottle plastics, like polypropylene (PP). But each polymer requires a different sorting and recycling process,” he says. PET, for example, melts at 260°C while HDPE melts at 120°C.

Another of the leading lights in plastics recycling is Greenstar WES. The Redcar-based firm has been involved in recycling HDPE and heavily contaminated films. Managing director James Donaldson says the key to good recycling is cleaning the product. Films can be more contaminated than bottles, but it is still possible to recycle them, although businesses and consumers would need to think differently. “Carrier bags are mostly LDPE, but lots of films could be used. A supermarket could say the consumer can have a recycled grey one for free, but pay if they want a brightly-coloured one,” says Donaldson.

Donaldson agrees the next big thing in recycling will be PP. As a popular packaging material, for example for ready-meal trays, PP has a solid end market, which is clearly important for a successful recycling business. “To make recycling work you’ve got to be good at manufacturing, find the high market value and you get a quality product,” he says.

Despite targeting particular materials, recyclers are likely to need to continue to handle all plastic types because of the range of plastics in packaging. Indeed, some welcome it if it helps boost recycling across the board. “Recycling has to become the easiest thing to do,” says Donaldson. “If it is easier to just throw it in the bin, then that’s what people
will do.”

RECOVERY’S POSITION
Recycling plastics is far from straightforward as the different polymer types and uses, not to mention food contamination and other packaging materials, make sorting individual polymers a difficult task. That said, a lot of work has gone into recovering these valuable materials, and as a consequence, the UK plastics recycling rate is on the up.

Polyethylene terephthalate (PET)
PET is among the best-recycled polymers in the UK. Its barrier properties make it material of choice for mineral waters and fizzy drinks and it can be recycled a number of times. A high proportion of mixed bottles, typically with HDPE or of a range of colours, are exported and when it is separated there is recycling capacity in Europe. The material is used to make food trays, and is commonly found as a laminate in films, again for its barrier properties.

High-density polyethylene (HDPE)
HDPE is most commonly used for milk. As such, investment in recycling seems assured to help meet the government road map target of 50% recycled material in milk bottles by 2020. It is also used for bleach and cleaning products. As with PET, price is dictated by quality and there are markets that offer a range of prices according to the level of contamination. A versatile polymer that can be manipulated, for example, to control transparency, HDPE is also found in films and some thin-gauge carrier and fresh produce bags. Film and carrier bag recycling is possible, but usually for low-value applications, so collections are limited.

Polyvinyl chloride (PVC)
PVC is a popular polymer for a range of applications, including packaging, where it is found in some thermoformed trays and also used in household wrapping films. However, part of the problem with PVC is that it can contaminate some PET collections. Through the introduction of reclamation facilities, that only focus on plastics, more colour and polymer separation is possible, which would help develop end markets.

Low-density polyethylene (LDPE)
LDPE is used in trays, but more commonly in films and bags. Recoup currently advises against the collection of films, although it is working with Wrap to develop collection facilities. It is a particular challenge given the relatively low value of the end product, although domestic film collection has been shown to be possible in trials. Another issue is the increased use of bioplastics and other materials in carrier bags that can contaminate the source.

Polypropylene (PP)
PP is probably the next big thing in plastics recycling, given that PP comprises a large proportion of mixed plastics collections, when bottles are taken out. PP is widely used in packaging in pots and trays, screw tops and as a film. It works as well in the freezer as it does in the microwave. It can be recovered and turned into a range of applications. However, black trays, whether PP or another material, are a problem as they are difficult to recover using existing sorting technology.

Polystyrene (PS)
PS is found in yoghurt pots and trays, and in its expanded form as protective packaging and hot drinks cups. Research has shown it to be quite a small part of the waste stream, but as with other rigid packaging it is likely to form part of future mixed plastics recycling trials.

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