A high-tech solution to the landfill problem

The Times
March 20, 2009

Mark Hunter

In a giant green shed on the site of a former steelworks in South Yorkshire, two rocket-shaped cylinders twist and steam like colossal pressure cookers as they churn through hopper-loads of household rubbish. Council lorries arrive, loaded with stinking black bin liners. Others leave with gleaming piles of recyclable tins and plastics.
But this is not a conventional recycling plant; all the waste here is the unsorted black-bag variety. Nor is it a mass burn incinerator, the fashionable alternative to landfill.
The shed is owned by Sterecycle, a company that uses steam heat from autoclaves to turn unsorted waste into a mixture of organic biomass and non-organic recyclable materials. The plant has permission to double its capacity to 200,000 tonnes of waste a year. About 50 per cent will be turned into biomass, 20 per cent will be recycled and the remainder will be sent to landfill. The company plans to build more plants elsewhere in the UK.
It is an approach to waste disposal that may help local authorities out of a hole. Of the 28.5 million tonnes of municipal waste collected in England last year, 54.4 per cent ended up rotting in landfill, leaching toxins into the groundwater and releasing greenhouse gases. There are about 500 landfill sites and the Department for Environment, Food and Rural Affairs estimates that all will be full by 2020.

Meanwhile, local authorities face increasingly punitive taxes and fines for landfill use. They are fined more than £150 per tonne for exceeding their landfill allowances. Hence their scramble to divert domestic rubbish anywhere but landfill. They have several options. We recycle or compost about 34 per cent of our waste.
This is, however, still short of the EU target of recycling 50 per cent of waste by 2020. The most popular alternative to landfill is mass burn incineration (MBI), which takes about 11 per cent of municipal waste. Its advantage is that it can recover energy from the burning rubbish. However, incinerators have an image problem with the public and are slow and costly to build.
This is where cheaper, more flexible technologies come in. Alternatives to MBI include gasification, biotreatment and, now, the autoclave process pioneered by Sterecycle.
Duncan Grierson, the chief executive of Sterecycle, said: “The autoclave process takes place in an enclosed building, so we don't have the Nimby problem that incinerators have. We got planning permission for this place in just four months and it took ten weeks to get permission to double capacity. Some incinerators have been trying for ten years and still haven't got planning permission.”
The Sterecycle plant is a fascinating mix of new technology and old. The two autoclaves form the centrepiece, using steam heat and pressure to turn the organic waste into a fibrous biomass material. This is shaken out through a cylindrical sieve known as a trommel. The company sells this biomass as a soil conditioner for land remediation projects and there are plans to use it as a green energy fuel.
With the biomass removed, the steam-cleaned, non-organic fraction of the waste travels through a series of mega-magnets, reverse magnets and blowers that sort the plastics from the metals. Wood and masonry are picked out by hand. At the far end of the plant there is a skip containing huge lumps of rock and concrete.
Sterecycle takes waste from Rotherham, Doncaster and Barnsley councils. Adrian Gabriel, waste strategy manager for Rotherham Borough Council, said: “We have looked at a number of options. Of those, Sterecycle seemed to be the most favourable and so far we are very happy with it.
“It's still a new technology, so we have begun with 75,000 tonnes a year and then plan to ramp that up to 150,000 tonnes from 2010. Farther down the line, it's likely that we will be using a number of different options including Sterecycle, the Sheffield energy recovery facility [an MBI] and with landfill still part of the equation.”
Mr Grierson agrees that there is a place for a range of technologies in Britain's drive away from landfill. He said: “This wouldn't have been possible ten years ago, because we would have been competing with landfill and back then nothing was cheaper than burying rubbish. But landfill isn't the cheap option any more, so that allows us to set prices that are attractive to local councils.”