“The original equipment was installed in the late 1990s as it was ideal for the size and shape of the tanks,” explained Anglian Water project manager Sean Rennie. “After nearly 16 years’ service, we decided that a complete overhaul of the system was needed to avoid unnecessary plant downtime.”
The bottom scraper mechanisms, wear plates and screw drives in all of the tanks were replaced and strengthened. The top scum scrapers in the final settled sludge tanks did not require replacement.
“In planning for the upgrade, we were happy to continue with the Zickert technology from Hydro. In addition, we have taken the opportunity to upgrade the failing electric vertical drive mechanisms by replacing them with hydraulically driven horizontal drives,” added Rennie.
The five month project involved four intermediate sludge tanks 45m long by 11m wide and six final settled sludge tanks 55m by 11m. As only one intermediate and one final settled tank could be drained at any one time, work had to proceed in sequence, rather than being able to upgrade several tanks at a time.
Intake to the Pyewipe WRC includes both domestic and trade effluent, which is screened and degritted prior to introduction to primary settlement. The separated water is treated in activated sludge tanks before going to final settlement tanks before it is discharged fully treated to the river. The settled sludge is then treated by further screening, thickening, blending and then mesophillic digestion. The methane captured from this process is then used to produce heat and power for the site through two CHP units.
