In June 2007 Northumbrian Water awarded a design and construct contract to Aker Solutions for a new advanced digestion (AD) plant at their Bran Sands site on Teesside.
Following laboratory trials, advanced digestion via thermal hydrolysis was identified as the preferred treatment process for the upgrade of Bran Sands Regional Sludge Treatment Centre (RSTC). The plant will treat indigenous sludges generated on-site and imported sludge from around the Northumbrian Water region.
The plant has been designed for a maximum throughput of 40,000 tds/annum and will generate up to 4.7 MW of electrical power for use on site at Bran Sands whilst at the same time producing a Class A biosolid product. Overall, this will reduce the whole Bran Sands site electricity usage by up to 50 percent.
The modification to the drying plant at Bran Sands RSTC utilises existing liquid sludge storage facilities and dewatering facilities for raw indigenous sludges and for the final digested sludge product.
The new AD plant consists of a twin cake reception facility and associated cake blending system, a two stream Thermal Hydrolysis Process (THP), three new anaerobic digesters, two gas storage units, four gas engines and waste heat recovery units plus two package boilers and associated water treatment facilities.
A new cake storage facility will also allow seven days storage of digested cake on site.
The project is nearing completion with all functional testing complete. Full process commissioning commenced in August 2009. It is anticipated that the plant will be fully operational by December 2009.
The paper will describe the outline design approach used by Aker Solutions, lessons learnt by all parties through the design and construction process and an update on current progress of the commissioning of the new AD plant.