Bellozanne Sewage Treatment Works (STW) in Jersey, originally built in 1959, was struggling to meet the needs of a growing population of over 105,000 people and increasingly stringent environmental standards.

The aging plant faced numerous issues, including unreliable equipment that caused frequent maintenance downtime and high costs. Foam clogging compressors in the gas mixing system and persistent ragging and grit buildup further disrupted operations.

Additionally, the use of lime to treat sludge generated a strong odour and cost £80,000 annually. Operating on an island presented additional logistical challenges, as delays in transporting equipment and parts meant the plant needed to be robust, reliable, and self-sufficient.

In collaboration with main contractor Doosan Enpure, Jersey’s Department for Infrastructure (DfI) took the opportunity to design a plant that addressed these challenges for the long term.

Key to this solution was the installation of Landia’s GasMix digester mixing system, which ensured consistent and efficient mixing of sludge while maximizing biogas production. By placing all moving parts outside the tanks, maintenance was simplified, eliminating the need for work at height or confined space entry.

Doosan Enpure’s pasteurisation technology replaced lime treatment, significantly improving sludge quality, eliminating odour, and enhancing the efficiency of the anaerobic digesters. Landia Chopper Pumps were also installed to handle thick, grit-laden sludge with minimal wear, reducing downtime and maintenance.

To further optimize operations, the plant addressed recurring issues with heat exchangers, which initially required weekly cleaning. The introduction of an air-line resolved this, while hardened impellers were added to the pasteuriser pumps to withstand aerated sludge, ensuring long-term performance.

The new plant at Bellozanne Sewage Treatment Works has achieved significant improvements in efficiency, reliability, and operational performance.

Gas production now generates up to 500 kW of electricity daily, with heat recovery further enhancing the sludge treatment process. Lime treatment has been eliminated, reducing costs and removing odour issues.

The robust Landia GasMix system and Chopper Pumps have delivered consistent mixing, reduced grit and rag buildup, and minimized maintenance downtime. The plant now operates more reliably, with improved sludge quality that is easier to distribute to farmers. Overall, the investment in high-quality equipment has ensured long-term performance and operational savings.