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Could sensor sorting see off RDF

Refuse derived fuel was initially welcomed by the industry as an apparently cheap and easy solution to deal with processing waste and avoiding increasing landfill costs. But many C&I MRFs are finding that the devil is in the detail, explains Stephen Almond, Tomra Sorting UK Sales Engineer

Every so often, an idea comes along which seems too good to be true. The concept of RDF presented C&I MRFs with the perfect opportunity to bypass expensive landfill costs by simply preparing, packing and exporting their waste.

The reality of this ‘solution’ has in fact been quite the opposite, with C&I MRFs paying through the nose for what has become an uneconomical, unstable and unsustainable process.

There’s no getting away from the fact that RDF is an expensive solution for dealing with complex C&I waste. The initial financial outlay for RDF processing requirements is significant, with a shredder, a large baler and a wrapping machine required as a minimum.  However, the real financial killer lies in the running costs – not only are operating costs high, labour and maintenance overheads can also be eye-wateringly high and often underestimated. And, if on-site costs weren’t high enough, C&I MRFs are then obligated to pay shipping charges based on material delivery to the end customer. It’s no wonder that many C&I MRFs who have adopted RDF processes now say their predicted savings per tonne on landfill are dwindling away, and that they would in some cases be cheaper to dispose of the material directly to landfill.

Costs aside, the end market for RDF is precarious to say the least. As with the industry as a whole, there is long-term uncertainty concerning the future restrictions on the export of material, not to mention increasing calls for a tax on RDF material.

This, in turn, has led to a lack of guaranteed long-term contracts and the risk that the RDF market could collapse with little warning, potentially leaving tonnes of expensively-produced material with no end destination. The worst-case scenario is that C&I MRFs could end up paying for the RDF process, only to have to pay again to landfill the material anyway. With the latest Environment Agency figures showing that 892,900 tonnes of RDF was exported in 2012, compared to just 272,000 tonnes during 2011, it’s clear that a sudden market collapse could be catastrophic for C&I MRFs.

The environmental credibility of RDF is dubious to say the least, with the ugly issue of the sustainability of waste export again rearing its head.  There’s also no escaping the fact that a significant proportion of material currently exported as RDF is being needlessly removed from the recovery/reuse cycle in the UK. Serious concerns have also emerged regarding the illegal dumping and inappropriate storage of RDF material, with the Environment Agency reporting an increase in incidents.  These problems only serve to position the RDF process as a potential reputational risk for even the most diligent of C&I MRFs.

Taking all of this into consideration, it’s clear to see that RDF is certainly not the ‘quick fix’ solution many in the industry had anticipated it to be. A strong and proven alternative available to C&I MRFs is materials recovery via sensor-based sorting technology.  Great strides have been made in sensor-based sorting technology, enabling C&I MRFs to recover much higher volumes of valuable end material than ever before. Tomra’s TiTech technology, for example, can achieve typical material purity rates of around 95%, with recovery rates of up to 70%.  As a comparison, manual or semi-automated techniques typically recover only 10-20%.

By utilising technology with a range of detection techniques to achieve the best results – including near infrared, X-ray transmission, visual spectrometer, colour line cameras and metal sensors – we can extract a wider variety of material than ever before. Plastics and fibre, films, rigid plastics, paper and cardboard and textiles and wood can all be recovered to an exceptional standard.

Aside from quality control, sensor-based sorting means no manual picking is required, leading to a reduction in labour costs.  Tomra Sorting’s equipment can process and maintain higher throughputs with consistent quantity and quality achievable 24/7.  The equipment also requires less physical space than traditional machinery.

Crucially, adopting this latest technology won’t break the bank for C&I MRFs.  Any initial outlay is an investment that is recouped quickly, with a typical payback period of just 12-24 months.

There is arguably no future for RDF as a stand-alone solution for C&I waste. MRFs must act now to adopt a stable, long-term approach and maximise the potential of materials and end markets.  There will always be a place for RDF or similar processes, but this place should be reserved only for small amounts of residue once all valuable materials have been recovered.

We’re already working with a number of C&I customers including Mid UK Recycling, Blakeley’s Waste Management, Devon Contract Waste, Gaskells Waste Services, Weir Waste and Spotmix – all of whom recognise that the days of high volume RDF production are numbered.  Our latest contracts with UK C&I MRFs will see huge volumes of material recovery from some 750,000 tonnes of C&I waste these plants will process over the next 12 months.  This is impressive, but other C&I MRF owners need to be encouraged to adopt commercially viable alternatives to RDF.

Case study: Devon contract waste

One of the UK’s first true C&I MRFs in mainland UK, Devon Contract Waste’s Exeter-based plant, processes an estimated 75,000 tonnes of waste per year. The waste stream, including metals, rigid plastics, wood, plastic film, paper and card, is processed on a 14 tonnes per hour single line.  After material is shredded at 300mm the fines are screened with a trommel and the 2D ‘lights’ are separated from 3D ‘heavies’ with a ballistic separator. Using near infrared Tomra Sorting technology, films are recovered along with paper and cardboard, rigid plastics and wood. Trevor O’Malley, Operations Director says: “We were spending over £1m on landfill each year, so we decided to invest around £2m to install a fully automated C&I waste processing plant. Three people operate the plant and we are achieving a 70% recovery rate of high quality materials. The plant has gone a long way towards achieving our zero waste to landfill target.”

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