Once fully operational, the ball mill will process around 100,000 tonnes a year of residual waste from households in Leicester, left after dry recyclables have been collected from the kerbside. The nearly fully-automated process grinds the material to below 80mm before recovering materials for recycling, composting or energy from waste.
Mick Davis, Biffa Leicester’s general manager, said that the ball mill is currently undergoing small scale trials, with performance guarantee trials due in June before the official launch later this year.
He added: “All the waste in the wheelie bins is bought to the site and put through the ball mill which will separate out recyclables in all sorts of ways.”
Biffa has a 25-year integrated waste contract with Leicester city council worth £300 million. DEFRA has pledged £30 million in Private Finance Initiative credits to support the contract, which has set targets to recycle and compost 40% of households waste with an additional 20% recovery by 2005.
Biffa Leicester, the partnership between the council and the waste company, believes a combination of kerbside recycling and community recycling centres as well as the ball mill and anaerobic digester will deliver the 60% diversion from landfill the contract requires.
Steve Weston, head of waste management at Leicester city council said he is pleased with the progress the 25 year PFI contract has made so far. “You can tell by the investment Biffa has put into this place, it gives us an opportunity to put in some real long term infrastructure,” he said.
Recovery
At the ball mill, metals are removed for recycling, plastics and paper are recovered for use as a fuel in cement kilns and the organic fraction is separated by size and sent to the anaerobic digester.
Mr Davis said: “Only about 25% of material going through the ball mill will go to landfill.”
The anaerobic digester, based on Severn Trent’s Wanlip site, is also due to come on line later this year. It has a potential capacity of 40,000 tonnes a year to process organic waste using aerobic and anaerobic processes and using the methane produced in the anaerobic stage to produce electricity.
The organic material produced by the anaerobic digester will be used on agriculture using routes developed by Biffa’s parent company Severn Trent’s sewage sludge treatment operations.
Mr Davis said that Biffa is on track to deliver its business case under the PFI agreement. “The first PFI contract was the Isle of Wight and it has delivered its full business case. The next PFI contract to deliver its full business case will be Biffa in Leicester.”
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