P-Fixation at Ringsend, Dublin

Irish Water works in partnership with 31 Local Authorities to deliver public water and wastewater services throughout the Republic of Ireland. Ringsend WwTP, the national utility’s largest wastewater treatment plant, treating over 40 percent of the country’s wastewater, is undergoing a major upgrade to support future population growth and comply with the European Union Urban Wastewater Treatment Directive (91/271/EC) to protect nearby waterbodies.

The Ringsend Wastewater Treatment Plant is being upgraded to include a new Phosphorous Recovery Facility within the confines of the existing WwTP and will operate in tandem with the Aerobic Granular Sludge technology to provide Enhanced Biological Nutrient Removal (BNR/EBPR) and to comply with the UWWTD final effluent standards applying to the discharge at the existing outfall to the Lower Liffey Estuary. These final effluent standards include limits on the concentrations of both phosphorus and nitrogen in the treated wastewater leaving the works. By applying the Aerobic Granular Sludge (Nereda®) technology at the Ringsend works, the quantity of phosphorus removed from the wastewater will be significantly increased while simultaneously safeguarding the environment of Dublin Bay and ensuring the plant operates in compliance with the Urban Wastewater Treatment Directive Standards.

The project will provide for the recovery of phosphorus from liquors generated from the dewatering of sludges arising at the plant, following the commissioning of the EBPR process. The project will specifically provide for recovery of phosphorus from these liquors in the form of a magnesium ammonium phosphate (Struvite) precipitate, with specified minimum levels of removal and recovery. The existing liquid stream of the Ringsend plant is based on preliminary treatment followed by primary settlement and secondary/tertiary treatment using the activated sludge process, which is currently being upgraded using the Aerobic Granular Sludge (Nereda®) process. The sludge stream is noted as providing thickening of Surplus Activated Sludge (SAS), Thermal Hydrolysis of mixed primary and SAS, Mesophilic Anaerobic Digestion and thermal drying. Dewatering stages provided upstream of the thermal hydrolysis units and upstream of the thermal dryers and the treatment of these liquors will provide the basis of the works to be executed as part of the Phosphorus Fixation & Recovery contract.

To learn more about the Ringsend Wastewater Treatment Plant, visit our Ringsend WWTP Upgrade Project Page.