The new sludge treatment facility at Yorkshire Waters Knostrop site in Leeds provides sustainable and efficient processing of up to 48,000 tonnes per year of dry sludge, which is a product of the waste water treatment process. This £72M scheme was promoted to allow the existing sludge incinerator built in 1993 to be decommissioned and to provide a sludge product suitable for use in agriculture whilst generating renewable electricity using biogas which is a product of the new digestion process. Previously most of the waste was incinerated or sent to landfill.
Paul Brown (Arup technical consultant) and Daniel Stevenson (Black and Veatch design and construction) gave a short presentation and then a tour of the new sludge treatment facility.
The facility receives sludge waste from the Knostrop site and from the areas surrounding Leeds, which is passed through thickeners and fed into the four large digester tanks, the largest in the Yorkshire Water region. The sludge is held in the tanks for 12 days to digest the waste and also produce methane biogas. The biogas is used to power boilers to heat the digesters and also powers two combined heat and power (CHP) engines to generate up to 4MW of electricity. After 12 days the sludge is treated with lime after which the sludge is suitable for use in agriculture. The CHPs will generate up to 23.4GWh/year of electricity which is equivalent to 55% of the power demand at the whole Knostrop site.
Mark Lees who attended the site visit said “The Knostrop site is very impressive. A major capital investment which I'm sure will benefit Yorkshire Water customers for many years to come, even if they don't know it! On a personal level it was great to see the enthusiasm of our two tour guides who had both dedicated a lot of time and effort during the project's development. Their pride in this achievement was plain for all to see. Well done!”