Melbourne’s Knox Transfer Station is pioneering refuse-derived fuel using an Australian-first technology to achieve a small particle size.
Over the years, Melbourne’s Knox Transfer Station has grown from being more than just a transfer station to a hard waste processor for a number of councils.
Operated by KTS Recycling and located in Wantirna South, the company also runs transfer stations in Coldstream, Skye and Wesburn.
Craig Davis, Process Manager at KTS, joined the company 14 months ago to support the company’s entrance into the refuse-derived fuel (RDF) market. RDF is used as a renewable substitute for fossil fuels in cement kilns and specialised energy-from-waste plants.
The motivation for KTS to get involved with RDF was inspired by its collection of hard waste and mattresses through parent company WM Waste Management Services. To maximise resource recovery and find a home for residual plastics, textiles, wood and other materials, the company started looking at RDF around five years ago.
“We were shredding and extracting metals from hard waste and mattresses and hand sorting cardboard and timber with the remaining material going to landfill,” Craig explains.
KTS’ expansion into recycling mattresses initially saw it shred and recycle metal with the remainder sent to landfill, but it believed it could be doing more.
“We didn’t just want to be seen as a wheel’s business and a processor, we wanted to do something different and stay ahead of the curve,” he says.
PROCESS ENGINEERING
In late 2017, KTS Recycling began to establish an interim RDF manufacturing facility at its Knox Transfer Station with support from Sustainability Victoria’s Resource Recovery Infrastructure Fund.
Extensive trial and error was required to ensure the material could meet specification, in particular the particle size for the fuel’s end user.
Craig’s background working with various shredders and grinders at SUEZ and Veolia helped fast track the process, experimenting with a number of different shredders, trommels and screens on-site.
However, despite extensive experimentation, no processes could consistently achieve its less than 50-millimetre output particle requirements. This led KTS to look outside of its existing resources and investigate a new and innovative resolution.
Owner Mark Jeffs flew to Europe last year to check out the UNTHA XR3000 mobil-e in action. As a specialist in machinery and manufacturing technology, Craig also went overseas earlier this year to inspect and test the XR3000.
Mark and Craig were both impressed by the single-pass shredding and lower rotation speed capabilities of the technology. As lower speeds generally have lower wearing costs and a reduced fire risk, the machine was seen as highly advantageous for KTS.
The XR3000’s ability to handle up to 30 tonnes of commercial, industrial and wood waste per hour was also a big plus.
Having previously engaged with FOCUS enviro on a number of other waste processing and technology choices, KTS turned to the company to provide an RDF solution.
FOCUS enviro then called on the product knowledge and experience of its technology partner UNTHA.
After discussing KTS’ requirements, the 37-tonne mobile machine was shipped to their Knox headquarters in July 2019, becoming the first ever Australian company to use the technology. The UNTHA XR3000 mobile-e has been applied successfully in more than 9000 successful installations worldwide.
A diesel mechanic by trade, Mark has achieved a long line of innovations through KTS and parent company WM Waste Management, including becoming one of the first organisations to trial and purchase electric refuse vehicles.
Mark says that alternative fuel is becoming more and more important in Australia and as a progressive environmental company KTS wanted to stay ahead of the curve.
“We acknowledged that by investing in world class RDF production technology, we could produce a high-quality resource, efficiently, and hopefully really drive the market for this crucial energy source,” Mark says.
Rod Tanner, Business Support Manager at KTS Recycling, says one of the most important criterions of the company’s operations is to ensure a reliable small particle size.
“The challenging aspect to our operations is that we make our product today, but we don’t really get feedback from the markets until weeks later so we have to do a lot of our testing locally to ensure we get our products right.”
Michael Strickland, KTS Project Manager, says that there would be big ramifications if deleterious materials ended up in the fuel.
COUNCIL COLLABORATIONS
Rod says the majority of customers in hard rubbish are local government and are accountable for landfill diversion targets, making the business case even more attractive.
“We service customers all over Melbourne and even some regional councils as far as mattresses go,” Rod says.
“We’ve actually got a contract with the North East Regional Waste Management Group so we service all the way up to Albury-Wodonga.”
He says that with more than a dozen customers working with KTS Recycling, the company is looking at opening up conversations with more commercial and industrial operators.
KTS’ process will involve taking RDF-compliant material from its other sites and processing it in Wantirna South.
Rod says that at this stage the main material going through the UNTHA is typical kerbside hard waste collected items, including mattresses and foam. Depending on calorific value results over the coming months, the company will also look at increasing its commercial and industrial waste processing.
Rod says that KTS is committed to doubling its initial output of RDF over the next four years.
While RDF remains relatively niche in Australia, the markets in Europe have grown exponentially.
According to data compiled by the UK association RDF Industry Group, the proportion of refuse-derived and solid recovered fuel has been steadily increasing each year since it began in 2010 to 2017. The sector is worth around £0.5 billion ($0.89B AUD) annually and RDF production supports more than 6800 jobs in the UK.
Gary Moore, UNTHA Director for Global Business Development, says the company is continuing to work with itscustomers to maximise throughputs, minimise impurities andmaximise margins.
“Australia is one of the world’s most exciting countries when it comes to waste-to-energy potential, and it’s great to now be a part of it,” Gary says.
A CHANGE IN DIRECTION
At the August Council of Australian Government’s meeting, federal and state and territory environment ministers agreed to work towards banning recyclable waste being exported overseas.
While a timeline has yet to be established, Robbie McKernan, FOCUS enviro Director welcomes the move and sees it as an opportunity for surplus non-recyclable material to be manufactured into RDF.
“The prime minister’s announcement will only fuel the need for alternative pathways for material that would otherwise be sent overseas,” Robbie says.
“RDF is a high quality resource and its success is well documented in markets around the world.”
Robbie says RDF is a first class alternative to landfill and can be supplied to many different types of energy facilities using fossil fuels.
Calorific value is another challenge and KTS is working on bringing its moisture content down. To rectify this, KTS is continually trialling a combination of different waste compositions with one of them including mattresses.
To support the shredding process, KTS has also acquired an EDGE density separator from FOCUS enviro to remove inert materials such as glass, ceramics and concrete prior to feeding material into the UNTHA.
KTS’ RDF process sees waste come in and be sorted and shredded into various piles before removing inerts through the EDGE density separator. The shredded materials are baled and wrapped into their finished product.
The new XR3000 mobil-e takes advantage of an electromechanical drive without having to forgo the advantages of a mobile machine.
Consistent 30-millimetre to 400-millimetre particle sizes are achievable.
Three different cutting concepts are available depending on the material and fraction size – a ripper, cutter or knife system. The system comprises an internal pusher that allows the material to be pressed against the shredding shaft to maximise production.
Robbie says FOCUS enviro now offers the complete alternative fuel production industry pre-shredders, density separators, industrial baling and bale wrappers and all technology components requirements to manufacture RDF.
“This means our clients can source a complete RDF production line from a single supplier in Australia which is unmatched in the industry,” Robbie says.
Robbie says the UNTHA X3000 mobil-e is unlike anything FOCUS enviro has previously seen in the marketplace.
“We had the chance to see it in the factory and some customer sites in the UK but it’s only when you see the machine in action that you understand it is in another league entirely,” he says.
“We’ve supplied shredders for decades so we were completely taken aback by the jump in machine capabilities and process diagnostics, from the drive system to pusher arm and the knife changeover features.”
Robbie says the ability to produce a homogenous and defined output fraction in a single pass has opened up more opportunities in difficult-to-shred applications.
“UNTHA are now dominating the plastic granulation, tyre-derived fuel, mattress, biomass, pulper ropes and e-waste resource recovery market with their ability to reduce materials efficiently with consistent size and minimal fines,” he says.
He adds that post-consumer and production waste plastics is another example where the machine is working with little to no competition in performance on an industrial level.
The range of shaft and cutter configurations means the shredders are suitable for thermoplastics, duroplastics and elastomers.
In the burgeoning waste-to-energy market, the shredder is also ideal for gasification or biomass markets.
“At the end of the day we’re making a product that substitutes black coal and cement kilns have to burn products regardless so if you can use a renewable fuel that’s best practice from a greenhouse gas perspective,” Michael says.
Craig says that the early results are highly positive and KTS has been able to trial new materials such as car and truck tyres, which has already reduced disposal and transport costs, allowing KTS to send pre-shredded tyres to an end user.
The testing forms part of KTS’ broader vision to be a geographical hub for PEF in Melbourne.
“Understanding where our waste stream is sitting will allow us to explore options for new residuals. We’re learning as we’re going, but we’ve already come a long way,” Craig says.
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