Buckinghamshire County Council is to roll out new food and garden waste collection services, and has awarded an interim biowaste treatment contract to waste management and recycling company Countrystyle Group.

Under the contract, Countrystyle will be responsible for the receipt and treatment of approximately 30,000 tonnes of green waste and mixed food and green waste from three of the four district councils in Buckinghamshire. They will also provide bulking services and haulage of all materials to treatment facilities using their own fleet of vehicles.

Buckinghamshire currently has a recycling rate of 45 per cent and pays around £11.6 million a year to dispose of waste to landfill. The council aims to increase its recycling rate to 60 per cent, a rate that it believes could be achieved by 2015/16 with the roll out of new district council recycling services. However, the increase in landfill tax means that even after this, if alternative ways to manage the waste are not found, the council will be paying £13 million a year to dispose of waste at landfill.

As part of the contract, the biowaste materials will be treated at Countrystyle’s Ridham in-vessel composting facility in Kent or at the Laverstoke Park Farm open windrow composting facility in Hampshire.

New services will help deliver ‘sustainable and value for money solutions’

Lesley Clarke, Buckinghamshire County Council’s Cabinet Member for Environment, said: “We are very pleased to be working with Countrystyle to support our district councils with the roll out of their new food and green waste collection services.

“The services provided by Countrystyle will help us deliver sustainable and value for money solutions, which will drive up the County’s composting and recycling performance.”

The in-vessel composting process

In-vessel composting processes organic waste, including meat and fish; garden waste; fruit & vegetables; and liquid food waste. This is shredded and prepared to an appropriate homogenised mix before being loaded into fully enclosed in-vessel bunkers complete with ventilated floors and wireless data logging probes.

Each bunker is equipped to send a constant stream of data back to the central control computer. The air from each bunker is extracted and piped into a natural bio-filter, cleansing the air before releasing it into the atmosphere.

Over a period of approximately one week, temperatures of 70oc are achieved and sustained for one hour. This procedure ensures the destruction of weed-seeds, pathogens and decomposition.

The product is then moved from the in-vessel composting bunkers to nearby bays where the material is left to mature. During this phase of around 6 – 8 weeks of negative aeration, the product is temperature and moisture monitored via a high specification aeration system to produce a stabilised, rich in nutrient, peat-free product. The product is then screened and certified as a PAS 100 certified compost fertilizer for agriculture and landscaping.

Open windrow composting

Windrow composting processes garden waste, such as grass cuttings, pruning and leaves in either an open-air environment or within large covered areas where the material can break down in the presence of oxygen.

The feedstock is shredded, mixed and placed into windrows along a non-permeable surface. The windrows are turned on a regular basis to improve oxygen content, distribute heat to regulate temperature and to distribute moisture, which takes around sixteen weeks to mature.

The compost is screened to remove contaminants such as plastics and metals, and to grade the compost for various end uses. Oversized materials are also removed and can be put back through the whole process until they have composted down sufficiently.