Ringsend Wastwater Treatment Works
Operations and Maintenance
Dublin, Ireland
Ringsend Wastewater Treatment Plant (WwTP), one of the largest wastewater treatment plants in Europe, serves the growing population of the Greater Dublin Area treating both domestic and industrial wastewater and was originally designed to treat a full flow (FFT) of 11.3m³/sec serving a PE of 1.64m. Currently, the WwTP receives and treats wastewater equivalent to 2.1m PE and with the ongoing major upgrades will be capable of treating flows and loads equivalent to 2.4m PE.
The treatment process includes a combination of preliminary, primary, high-rate secondary, and tertiary stages, facilitating the on-site reuse of energy, heat, and water before safely discharging the treated water into Dublin Bay.
CAW (Celtic Anglian Water) has been the provider of operations and maintenance services on the site on behalf of Uisce Éireann since 1999. During this time CAW has delivered over €100m of capital works whilst consistently maintaining the operational integrity of the treatment works. CAW also operates and maintains water and wastewater treatment plants for Uisce Éireann in Waterford and Sligo.
The Ringsend WwTW has been, and is, the home to some of the most innovative wastewater treatment technologies, fundamental to protecting Dublin Bay’s beaches and progressing towards sustainability goals to protect and restore the environment. Previously the world's largest double-decker Sequence Batch Reactor (SBR) plant was located at the Ringsend Site, which has since been replaced with the more advanced Nereda® Activated Granular Sludge technology. In addition, the Ringsend WwTP also includes a cutting-edge sludge treatment facility which includes the advanced treatment technologies of Thermal Hydrolysis followed by Ephyra® Anaerobic Digestion.
Site Highlights
Site Highlights
CAW focuses on delivering Uisce Éireann’s water quality, environmental and sustainability objectives through ongoing optimisation, consultancy, and the design and implementation of improvement projects and upgrades. We are committed to:
- Maximising the performance and efficiency of the plant through continuous optimisation.
- Ensuring compliant discharge with EPA and Uisce Éireann’s standards.
- Ensuring the highest levels of on-site Process and Operational safety.
- Maximising biogas quality and yield to power on-site operations.
- Production of Class A Biosolids to use as fertiliser on agricultural land.
As part of a major upgrade programme, Uisce Éireann is investing heavily to increase the plant’s treatment capacity to 2.4m PE and enhance the level of secondary treatment. In addition to being the provider of operations and maintenance services at the site, CAW has delivered multiple capital works projects and, as part of the FaCT3 Consortium, has completed two major projects in the current upgrade programme, with two more underway.
CAW took over the operations and maintenance of the Ringsend Wastewater Treatment Works (WwTW) in 1999 under a design, build, and operate contract, which included replacing the original works with a new plant to provide preliminary, primary, secondary, and tertiary (disinfection) treatment for the Greater Dublin area. The original treatment works stayed operational throughout the construction period. The new works began operation in 2003 upon completion of the construction phase.
Since then CAW has been responsible for the full operation and maintenance of the complex, and growing Ringsend WwTW. CAW manages several complex processes and technologies to ensure high-quality treated effluent and maximise resource recovery to provide sustainable services fit for the future.
These processes include:
- Preliminary Treatment via fine screens and aerated tanks;
- Primary Lamella Settlement;
- Secondary SBR Treatment;
- Tertiary UV Treatment;
- Advanced Sludge Treatment, via CAMBI hydrolysis, Ephyra® digestion and thermal drying;
- Biosolids Recycling.
To cope with the growing needs of the Ringsend WwTW and ensure the highest standard of wastewater treatment, CAW has implemented key capital works projects.
CAW provides
- 24-hour operational maintenance services, including emergency repair, to ensure effective treatment up to the Full Flow to Treatment (FFT) design capacity;
- Long-term asset management, focused on proactive refurbishment and maintenance, which includes both minor and major works to maximise performance and lifespan;
- Ensuring that the quality of the final effluent being discharged into receiving waters meets with both the EPA licence consent standards and Uisce Éireann’s KPIs;
- Management and maintenance of the Anaerobic Digestion and CHP Technologies and processes to maximise biogas output used to generate both heat and electrical power;
- Full management of production and recycling of the Class A Biosolids to agricultural lands, including implementation of the required Nutrient Management Protocols and Reporting in collaboration with the Local Authorities;
- Ensuring compliance with the site environmental plan to protect the local environment and community from harm or nuisance;
- Management of the Capital Replacement Fund in cooperation with Uisce Éireann;
- Ensuring high standards of health and safety for all on-site operations to comply with legislation and the individual policies of both CAW and Uisce Éireann;
- Monthly reporting under the Performance Management System (PMS) of Water Services National Training Group (WSNTG);
- Consultancy services on innovation strategies to improve performance, reduce emissions and achieve net zero goals through plant major upgrades.
Milestones and Highlights
Throughout our tenure, we have delivered critical upgrades and introduced advanced treatment systems that have enhanced the plant's capacity, all while maintaining performance and regulatory compliance.
Here we highlight selected key milestones that demonstrate our commitment to providing reliable and sustainable services to Uisce Éireann and the Greater Dublin population.
Two major infrastructure upgrades to the SBR plant
CAW was an integral part of the project team delivering two major infrastructure upgrade projects to increase treatment capacity and operational efficiency by retrofitting the SBR plant with cutting-edge Nereda® advanced granular sludge technology. Read more on our case studies for the SBR Retrofit Hybrid 1 Contract and the SBR Retrofit Block 2 Contract.
Ultrafiltration and Reverse Osmosis Plant
CAW installed cutting-edge ultrafiltration and reverse osmosis systems to enable water reuse on-site. We are now implementing a further ultrafiltration membrane bank upgrade project to double the output from 33m3 per hour to 66m3 per hour, to further reduce the plant's dependency on mains water.
Electrical Upgrade to increase renewable energy generation
We are currently leading a project to deliver a 5th CHP engine to maximise the use of Biogas generated on-site. When complete, the additional engine will generate an additional 3,500 MWh of electrical and 5,000 MWh of thermal renewable energy to power site operations.
UV Disinfection Upgrade
We are in the process of managing the upgrade of the UV disinfection system, to increase treatment capacity by nearly 20% and improve energy efficiency at the works. This is due to be completed by the start of the bathing season in 2025.
Innovative solutions to maintain performance
During many projects, we have had to come up with innovative solutions to ensure continuity of operations. Two examples include:
- The implementation of the largest over-pumping exercise in Ireland, where the team collaborated to divert flows of up to 2.5 million cubic metres per second for an extended period during essential works.
- The design and implementation of a custom hoisting mechanism using marine buoyancy aids to raise pipework, and the design and deployment of a floating pontoon to enable the installation of new pipework at the SBR plant to enable uninterrupted operation of the SBR cells during the works.
Taking over the operation of a new facility after a significant capacity upgrade
Following a capacity upgrade at the works, we successfully took over the new 400,000 PE Nereda® AGS plant at Ringsend in January 2023, which serves the equivalent population to a mid-sized city. Since then, we have maintained compliance while continuously optimising performance and efficiency. This included on-site lab services to further optimise plant processes and improve operational efficiency.
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