Pressure cooking green power for the future
26/06/2007
Sludge remaining after sewage treatment is to be converted into green energy to power Northumbrian Water’s biggest works, in a major move to environmental sustainability.
The process change at the 52-acre treatment works at Bran Sands on Teesside will, in total, cost £32 million with work scheduled to start this autumn and the plant planned to be fully operational by spring 2009.
It will be the biggest single plant of its kind in the UK using the emerging new technology of ‘thermal hydrolysis advanced digestion’ and will put Northumbrian Water at the forefront of the industry.
Sludge will be squeezed to further reduce water content before being loaded into giant steam pressure cookers (at 165 degrees centigrade) and then cooled before being fed into tanks for bacteria to digest.
The methane given off by the bugs eating the waste will then be collected in 11-metre diameter biogas storage bags (similar to hot air balloons) before being used to fuel engines to create enough renewable electricity to power about half of the entire treatment works site at Bran Sands.
Heat and steam generated will also be captured and utilised efficiently elsewhere in the process.
The digested sludge cake remaining after the process will be a Class A biosolid - a safe and low odour product containing no detectable levels of pathogens, such as E-coli, and will be used as a valuable agricultural fertiliser.
The new process will improve efficiency and reduce the company’s carbon footprint. It will reduce more than 500,000 tonnes of sludge - from the treatment of domestic sewage and industrial effluent from a population equivalent of 1,900,000 people - to about 60,000 tonnes and will generate five mega watts of green electricity.
Northumbrian Water’s Operations Director, Graham Neave, said: “This is another leading development at our Bran Sands works which has already won international awards for innovation.
“Development of this sustainable process to re-use and recover valuable resources from sludge and create renewable energy puts Bran Sands once again in the national spotlight as a centre of environmental excellence.”
The new process at Bran Sands will treat sludge from Northumbrian Water sewage treatment works south of the river Tyne and in the Tees Valley.
Sludge from sewage treatment on Tyneside and north of the river Tyne will continue to be treated by the traditional methods at Northumbrian Water’s Howdon works.
Current sludge ‘tumble drying’ facilities will be retained at Bran Sands as a strategic contingency backup.
The £28 million contract to design, construct, install and commission the new facility has been awarded to Aker Kvaerner Engineering Services Ltd from Stockton in the Tees Valley.
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For further information contact Alistair Baker 0191-301-6851.