Facts & Figures

 ClientIrish Water
 LicenseeEPS Group
 LocationCarrigtwohill, Ireland
 Operation Start2016
 Project TypeGreenfield, Brownfield, Retrofit
 Process ConfigurationPre-treatment + Nereda
 Nereda Design Capacity:
  • Dry Weather Flow7 MLD
  • Peak Flow844 m3/h
  • PE30,000 PE (PE = 60 gBOD/d)

About the Carrigtwohill Nereda® WWTP

The town of Carrigtwohill is located in County Cork, Ireland, about 12km east of Cork city.


The wastewater treatment plant (WWTP) at Carrigtwohill in County Cork was identified in the Cork Development Plan and the Cork Area Strategic Plan as an area of potential high growth. A substantial increase in the capacity of the foul and surface water networks – as well as the treatment plant – was required to cater for the increased hydraulic and biological loads. This, in combination with more stringent discharge standards, necessitated the construction of new wastewater treatment facilities at Carrigtwohill. The construction of the wastewater treatment facilities at Carrigtwohill was procured under a design/build/operate (DBO) form of contract.


The contract for the construction of the treatment plant, which involved a circa €12 million investment by Irish Water, was awarded to an EPS-Sorensen Joint Venture partnership in June 2014. This contract included the design, construction, operation and maintenance of the WWTP and associated works, including pumping stations, intake works, pipelines and ancillary works. The design capacity of phase one of the new WWTP is 30,000 p.e. (biological), with provision for a future extension to 45,000 and 60,000 p.e. in phases two and three (inlet and sludge). The main contractor, EPS, elected to use Nereda reactors as the main process treatment tool at this new plant. The construction phase took place over a 14-month period.


Commissioning began in December 2015 and the start-up in early 2016. According to Process Design Engineer Robin Kraan of Royal HaskoningDHV the commissioning and start-up went very well. “We are ahead of schedule and now can treat more wastewater than previously planned. This is partly due to a well thought out design, in cooperation with Nereda licensee for Ireland EPS. The lessons learned from previous projects have led to a beautiful, robust plant, with a well-oiled commissioning.” Upon completion, this plant is now a key learning centre for Irish and international clients.

In 2016, EPS won the Green Technology Award for introducing the revolutionary Nereda technology to the Irish wastewater treatment market.

The local benefits of the project

Nereda logo small Greater treatment capacity
Nereda logo small Environmental benefits
Nereda logo small Future proof compliance
Nereda logo small Small carbon footprint
Nereda logo small  Cleaner water