Bellozanne STW Replacement of Sludge Thickeners

Tender description

The Bellozanne Sewage Treatment Works (STW) is located at Bellozanne Valley Road, St Helier, Jersey JE2 3JX. The Site lies within the Bellozanne Valley, approximately 4km from St Helier. Access to the site (Gate 4) is gained off the Bellozanne Valley Road running approximately north to south along the valley’s western side. The existing Sludge Thickening and Dewatering (STAD) facility was constructed in 2011-2012, incorporating the reuse of two existing centrifuges (one originally commissioned in 2005, and a spare procured in 2009). The STAD Facility was fully commissioned in 2012. The centrifuges are programmed for replacement in 2026. The STAD facility thickens and dewaters the sludge created from solids settlement during the treatment process. The main items of plant consist of Duty/ Standby Drum Thickeners which thicken Surplus Activate Sludge (SAS) from the Activated Sludge Plant (ASP); and Duty/ Standby Centrifuges which dewater the digested sludge from the Anaerobic Digesters on the adjacent Sludge Treatment Platform. The overall process produces Biosolids Cake as a byproduct, which can then be applied to land for recycling, stored on site or processed through the Energy Recovery Facility (ERF). The Sludge Thickeners are a crucial component of the STAD facility and the STW. A loss or substantial reduction in the Sludge Thickener’s ability to manage and process the SAS would have significant impact upon the department's ability to dispose of digested sludge. The existing Sludge Thickeners are nearing the end of their useful design life and obtaining replacement parts has become difficult and prolonged resulting in an unacceptable level of risk for the Infrastructure and Environment Department. The Infrastructure and Environment Department are replacing the Centrifuges in 2025/6 and they plan to replace the Sludge Thickeners in 2026. Keywords: Drum Thickener