A £10 million biogas facility that uses anaerobic digestion (AD) to treat 45,000 tonnes per year of source separated municipal food waste has been officially opened in Wallingford, UK.
The plant has been developed by Oxfordshire based organic waste treatment specialist, Agrivert under a 20 year contract to provide a complete organic waste treatment solution for Oxfordshire County Council. The plant will also process waste for The Royal Borough of Windsor and Maidenhead (RBWM) under a 25 year contract.
The company said that the other plant is one of six organic waste recycling facilities that it is developing to meet the terms of its contract with Oxfordshire County Council, and that the others comprise four composting sites and a further AD facility at Cassington.
According to Agrivert in addition to treating food waste which has been separated at source under municipal waste contracts, the plant will recycle local food waste for restaurants, pubs, retailers and food manufacturing outlets. Much of this food waste is currently being sent to landfill.
The organic waste specialist explained that once delivered to the site, the waste is decontaminated and processed into a 'thick soup', and is then pumped into the digesters where bacteria break it down in the absence of oxygen, producing methane.
The methane is captured, cleaned fed into a gas engined generator, which produces the 2.3 MW of electricity that is fed into the National Grid - enough energy for 4000 household.
The company added that the plant also generates renewable heat, some of which is used to heat the pasteurisers and the digesters. There are also plans to use additional heat to dry woodchips for fuel at a later date.
The digestate material that leaves the plant at the end of the 100 day process is pasteurised and used as a bio-fertiliser which the company said can displace chemical fertiliser produced in a carbon intensive process.
According to Agrivert applying digestate to arable land also returns much needed organic matter to the soil. The Wallingford plant will produce enough digestate each year for over approximately 2500 acres of local farm land.
Win-win for local authorities
The company said that that Wallingford facility is the second AD plant that it has delivered within Oxfordshire, and that tecycling food waste enables Oxfordshire and RBWM to deliver high levels of recycling, and dramatically reduce the financial and environmental cost of sending food waste to landfill.
According to Agrivert, as a result of their partnership with it, three of Oxfordshire’s Districts are in the top 10 of local authorities for recycling in England, and Oxfordshire was the top performing Waste Disposal authority in 2011/12.
The company added that the Royal Borough of Windsor & Maidenhead has recently extended its food waste collection service to all local households and this means residents who recycle food can benefit from the council’s rewards for recycling scheme.
The borough was also the first local authority in the UK to actively promote Recyclebank rewards for household recycling and the food waste stream is now recycled by Agrivert’s.
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