Sligo Wastewater Treatment Works
Operations and Maintenance
Co. Sligo, Ireland
Since 2009, CAW has operated and maintained the Works, located in a Special Area of Conservation (SAC), on behalf of Uisce Éireann, consistently delivering exceptional standards that prioritise biodiversity and environmental protection.
The Works is situated in a bunded area of reclaimed marshlands at the mouth of Sligo Harbour that supports vital habitats for migratory waterfowl and seal colonies. The outfall directs recycled water adjacent to the Cummeen Strand to Drumcliff Bay Irish Natura 2000 site.
Sligo WwTW is one of four sites managed by CAW on behalf of Uisce Éireann, including the Ringsend WwTW in Dublin, one of Europe’s largest wastewater treatment plants. The Sligo Works provides comprehensive wastewater treatment processes, including primary settlement, biological secondary treatment, final settlement, and UV disinfection for recycled water. It is designed to manage wastewater up to a population equivalent of 50,000 from Sligo and the surrounding county.
In addition to its treatment capabilities, the facility features a Sludge Reception and Advanced Treatment Hub to produce Class A Biosolids that are recycled to fertilise agricultural land. This hub receives and processes sludge generated throughout the local area, as well as its own.
Site Highlights
Site Highlights
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Goals
CAW remains focused on achieving Uisce Éireann’s goals for water quality, environmental stewardship, and sustainability through continuous optimisation activity, providing expert consulting support, and delivering improvement projects and upgrades. Our commitments include:
- Ongoing continuous optimisation activity to maximise plant performance and efficiency.
- Assuring compliance with Environmental Protection Agency (EPA) regulations and Uisce Éireann’s strict standards.
- Maintaining the highest standards of process and operational safety.
- Optimising biogas production to power on-site boilers for the sludge pasteurisation process.
- Production of Class A Biosolids, used as fertiliser on agricultural land to support the circular economy.
Operations and Maintenance Service Provision
CAW oversees the complete operation and maintenance of the Sligo wastewater treatment facility, managing a range of complex processes and technologies to ensure high-quality treated effluent while maximising energy recovery for long-term sustainability. These processes include:
- Inlet Screening;
- Grit and FOG removal;
- Odour control;
- Primary settlement;
- Biological secondary treatment;
- Activated Sludge secondary treatment;
- Advanced sludge treatment including pasteurisation, Anaerobic Digestion and dewatering;
- UV disinfection for bacterial reduction to protect shellfish in the Sligo Bay area.
By effectively managing advanced sludge treatment processes, we ensure that the resulting biosolids consistently meet stringent 'Class A' standards, making them safe for recycling as fertiliser on agricultural land.
CAW Provides:
- Round-the-clock operational maintenance and emergency repairs;
- Proactive asset management to maximise performance and increase asset lifespan;
- Compliance with the Irish and EU Drinking Water Regulations;
- Rigorous standards of on-site health and safety, and process safety, following CAW and Uisce Éireann policies;
- Comprehensive environmental and compliance plans to safeguard the local community and environment;
- Management of the Capital Replacement Fund in collaboration with Uisce Éireann;
- Monthly reporting through the Performance Management System of the Water Services National Training Group (WSNTG);
- Active contribution to social and environmental improvements to benefit the local area;
- Advisory services incorporating innovative approaches to enhance performance and reduce whole lifecycle carbon emissions.
Sligo WwTW Highlights
Protecting Marine and Aquatic Life
Given its proximity to a Natura 2000 site and the rich bird and aquatic life in the area, the Sligo Wastewater Treatment Works ensures thorough treatment, including an advanced UV disinfection stage that further reduces bacterial content. This final step adds extra protection for the shellfish and aquatic ecosystems in Sligo Bay, with wastewater treated to the highest standards to safeguard both the shell fisheries and the natural environment.
A Hub Centre for Resource Recovery
The Sligo Works serves as a Regional Sludge Hub receiving and treating wastewater sludge from smaller plants within Sligo and neighbouring counties. The facility’s Advanced Sludge Treatment process includes thickening, blending, pasteurisation, digestion, and dewatering, producing Class A biosolids. These are then recycled as nutrient-rich organic fertiliser for agricultural land, contributing to sustainable waste management and providing value to the wider community.
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