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Closing the Chinese Loop

Although leeds-based Cromwell Polythene’s focus has always been on the recovery and recycling of polyethylene film for reprocessing into products such as sacks and bags for the storage and collection of waste and recyclables, higher levels of contamination sometimes means it is not always viable to reprocess to a film grade. As a result, some material inevitably ends up being downgraded - and thereby devalued - with its use limited to less challenging manufacturing application such as injection-moulded buckets or bins.

While promoting the principals of closed loop recycling and working with our manufacturing partners to keep as much material in the UK as possible, the global market for plastic waste is now so significant that it cannot be ignored. Neither can we disregard the contribution that it makes to support the recovery and reprocessing of recyclable plastic waste that might otherwise be landfilled in the UK. Such plastics generally require a degree of sorting and cleaning to the extent that they cannot be viably recycled in the UK, leaving us to work with overseas reprocessors, notably in the Far East that, in turn, feed reprocessed material to the manufacturers of second life products.

“This particular application is a more genuine export market since the demand for the finished product comes from the domestic market in China”

Through one of these reprocessors came a request to supply ‘other’ types of plastic packaging waste to feed the growing demand for a downstream manufacturing application in China. So Cromwell has recently been trialling the purchase of mixed plastic containers from Cumbria Waste Recycling to be reprocessed in China and used in the manufacture of horticultural and agricultural irrigation systems.

The trial marks a significant expansion of the range of post-industrial plastics and cardboard that Cromwell already recovers. It also builds on the company’s existing closed loop relationship with Cumbria Waste Recycling, from which we purchase plastic collected both at the kerbside and from commercial customers.

Historically, virgin medium-density polyethylene (MDPE) has been widely used for pipe extrusion, although it is not unheard of for some recycled material to be used. In the past this would typically have included cleaner production waste. By contrast, the China process uses both low-density polyethylene (LDPE) and high-density polyethylene (HDPE) from post-industrial and post-consumer packaging waste to produce a mixed density HD/LDPE product with properties comparable to MDPE. Typical feedstock includes commercial/industrial waste such as used LDPE packaging films, pallet covers, stretch films and local authority kerbside collections of household recyclable waste, typically HDPE milk bottles.

The recovered plastic from Cumbria Waste Recycling is sorted, graded and baled, either on-site at its own facility in Carlisle or at Cromwell’s dedicated recycling centre near Leeds, before being shipped as 20-tonne loads in 40ft sea containers to China. On arrival at the reprocessor it is sorted by material type – HD, LD, PET - although PET is separated and sold for another process. Then it is shredded, washed and re-extruded into pipe-grade recycled pellet. The process for film-grade plastics from post-industrial packaging for bag production is similar, although the material is handled separately. If the level of contamination means that it cannot be remade into bags, it can be blended into the pipe-grade material.

Although some ‘export’ markets for plastic waste see the material reprocessed in China and re-exported as bags or other finished products, this particular application is a more genuine export market since the demand for the finished product comes from the domestic market in China. The end product is, of course, 100% recyclable itself, thus fully closing the loop. What goes around
comes around, as they say.

James Lee is managing director of Cromwell Polythene

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