"This new contract will be more environmentally friendly and cheaper than continuing to landfill and will see Cambridgeshire once again leading the way in waste management"
Cllr John Reynolds Cabinet member for environment and community services
The Cambridge County Council Executive has given provisional approval for the 28-year Private Finance Initiative contract with Donarbon to deal with the Council’s residual wastes using the MBT process.
Donarbon are proposing to build a new Mechanical Biological Treatment (MBT) facility at their existing Waterbeach landfill and recycling site on the A10 north of Cambridge. The facility will also include the provision of an Education Centre to raise waste awareness and help the local authorities promote waste minimisation.
The new facility will treat mixed household waste by mechanically removing some materials and biologically treating others. The process will recover some materials for recycling and produce a stabilised compost-like material which can be used in certain land restoration activities or can be landfilled as treated waste.
The £750m contract under the PFI scheme will be subject to full council approval at a meeting on 15 May. Central government is also supporting the project to the tune of £35m.
In 2005/6, 300,000 tonnes of household waste was produced in Cambridgeshire of which a substantial 43.5% was recycled and composted. The balance, approximately 170,000 tonnes, was landfilled. However current estimates of waste arisings range from 143,000 to 188,000 per year over the next 28 years. The recycling rate was expected to exceed 50% in 2006-07.
Some of the residual waste to be accepted by the Donarbon facility will be delivered from transfer stations at Alconbury and Wisbech in Huntingdonshire and Fenland respectively.
The Government has given the county council Beacon Status for their high performance in recycling and waste procurement, effectively a guide to other local authorities on best practice.
The waterbeach site
The Waterbeach site has has dealt with construction, demolition, commercial and industrial wastes for some time and since 2001 has accepted green waste for composting. From 2002, mixed household waste for disposal, from the districts of Cambridge City, South Cambridgeshire, East Cambridgeshire and Fenland have also been accepted at the site.
An integrated waste management facility received planning consent in 2001 which included the construction of a new roundabout, facilities for the recycling of wastes and aggregates, a new building for the treatment of household waste, extraction of clay, sand and gravel, landfill of remaining waste and remediation of an old landfill together with restoration proposals.
Much of the 2001 development work has been undertaken including the provision of an in-vessel composting plant which will be a useful supplement to the MBT facility.
The MBT plant
The new MBT facility will be split into two main halls dealing with mechanical separation and biological treatment:
Initial mechanical separation of the residual wastes arriving at the plant results in 4 main waste streams:
- A rolling fraction consisting of metals and plastic bottles for recycling
- A flat fraction of paper and plastic film and textiles for recycling or refuse derived fuel production
- A fine fraction of mainly organic wastes for input into the biological treatment system
- A residue for landfilling
The Biological treatment process will producer a stabilised compost like material suitable for soil improvement or for deposit in landfill as a treated waste with a lesser environmental effect.
Change in philosophy
An earlier planning permission had been obtained for an MBT plant with the fine fraction, which contains the organics, to be transferred by vehicle to the organic treatment centre where it would be treated through anaerobic digestion and composting.
However the process was changed to some extent and the biological element now only includes composting and does not include anaerobic digestion.
Donarbon considered anaerobic digestion to be “more appropriate for dealing with liquid and food wastes rather than mixed household waste”. The outcome of this change was a requirement for a larger building being to provide a fully enclosed compost facility.
The company says that a small anaerobic digestion pilot plant is currently operational on site for research and development which is processing liquid/food wastes.
The intended site covers around 3 hectares at the front of the existing Cambridgeshire Waste Management Park. There are 3 main buildings to be developed, planning permission already being in place. The waste reception building will be 50m long by 40m wide, the preparation building, which also includes the Education Centre, will be 54m long by 45m wide and the composting building will be around 180m long by 74m wide.
Energy and resources
In terms of sustainable energy, consideration is being given to the use of solar panels on the roof of the buildings for power generation. Consideration is also being given to utilisation of electricity produced from landfill gas which is produced in the adjacent landfill operations, with the balance of energy being exported into the national grid.
The new facility is to be designed to make best use of natural light and will also have energy efficient light and power systems.
In the design and construction of the MBT facility, use of recycled materials will be included and wastes from the construction process will be recycled through the existing site facilities.
Comments
Cabinet member for environment and community services councillor John Reynolds said:
“Cambridgeshire has record breaking recycling rates but we can do better. We cannot carry on dumping rubbish that can’t be recycled in landfill.
“This new contract will be more environmentally friendly and cheaper than continuing to landfill and will see Cambridgeshire once again leading the way in waste management.”