Irish Water was created by the Irish Government in 2013 and supplies drinking water to the whole of the Republic of Ireland. The company is investing over €65 million as part of their National Disinfection Programme involving the upgrade and standardisation of disinfection systems currently installed in over 800 sites including water treatment plants, pumping stations and reservoirs. Their design and build contractor in Limerick and Tipperary is Glan Agua, whose task is to upgrade existing disinfection systems to improve drinking water quality and ensure compliance with the current Drinking Water Quality Regulations.
Challenge
“One project we undertook was a comprehensive upgrade of Bruree Pumping Station in Co. Limerick”, says Robert Kearney Project Manager at Glan Agua. “This involved upgrading the existing sodium hypochlorite system to provide enhanced control for improved bacteriological compliance and installing a state-of-the-art duty/standby UV system to ensure protozoan compliance and improve drinking water quality.” Glan Agua decided to supply the self-contained hypochlorite dosing and UV system as a fully pre-fabricated unit from their off-site assembly facility in Cahir, Co. Tipperary. This would allow a high-quality product to be constructed in a controlled environment and tested prior to delivery and installation, reducing disruption to the operation of the existing works. It would also provide a standard solution for future projects in Limerick and Tipperary with the added advantage that operations and maintenance staff would see an identical plant at each works, reduce spares holding and minimise maintenance costs. For the UV system, they turned to Enva, one of Evoqua’s customers in Ireland.
Solution
Working closely with Enva and Glan Agua, Evoqua proposed the UVLX-1800-6 low flow system, which would become an integral part of the Glan Agua standard package for other water schemes. It comprises a 316L stainless steel IP66 reactor containing a single 800W low pressure amalgam lamp giving best-in-class efficiency and lamp life. The reactor is equipped with UV intensity and temperature monitoring and an automatic wiper system to ensure peak performance. A Spectra II local control panel controls the lamp output by varying the power in response to flow, UV transmittance and UV intensity. The system is designed for low flows of variable quality water, so provides the high degree of flexibility needed in a standard package.
Whilst the prime role of the UV system is to ensure that protozoans like Cryptosporidium are destroyed, it also acts as a primary disinfectant to reduce bacteria and viruses as well as improving the palatability of the water. By removing much of the bacterial load, UV reduces the hypochlorite dose required to maintain a free chlorine residual, making chlorination control simpler and reducing the potential for taste and odour and trihalo-methane formation.
Results
The Bruree project was completed in July 2019 and was so successful that Evoqua has now supplied twenty of the UVLX-1800-6 UV units to Glan Agua for projects for Irish Water schemes in the Limerick and Tipperary counties of the Republic of Ireland.