James Leigh, Regional Disinfection Lead at atg Evoqua explains how the company developed a product to meet a specific need.

Irish Water is carrying out a major disinfection programme at water treatment plants which will help to safeguard water supplies and improve the quality of drinking water for homes and businesses throughout the Republic of Ireland. The upgrading of disinfection systems under the National Disinfection Programme will minimise the risk of people having to boil their water. Irish Water is investing over €65 million as part of the 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, part of Mota-Engil Engenharia e Construção, Portugal’s leading EPC contractor. Their task was to upgrade existing disinfection systems to improve drinking water quality and ensure compliance with the current Drinking Water Quality Regulations.

“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.” It seemed to Robert’s team that the easiest way to complete the project in the shortest time would be to design a self-contained hypochlorite dosing and UV system that could be fully pre-fabricated in Glan Agua’s 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 would cause minimal 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 protozoan control, Glan Agua chose UV. This chemical-free process has a long track record in water disinfection and is particularly effective against protozoans like Cryptosporidium and Giardia and other chlorine resistant microorganisms. UV is a specialised technology and Robert’s team needed help with the design development. They found a willing collaborator in Enva, one of atg Evoqua’s business partners in Ireland. Working closely with Enva and Glan Agua, atg Evoqua designed a low flow UV system, the UVLX-1800-6, which would become an integral part of the Glan Agua standardised design and build for other water schemes. Like all atg Evoqua’s municipal water treatment UV systems, the product is designed to meet the validation protocols of the US EPA Ultraviolet Disinfection Guidance Manual. It also meets the latest UK and European potable drinking water regulations, including the WIMES 801.B specification guidance for closed vessel drinking water UV systems.

atg Evoqua’s UVLX-1800-6 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.

Jamie Barry of ENVA worked effectively as the collaborative engineering link between Glan Agua and atg Evoqua. “It was really enjoyable working with James Leigh at atg Evoqua and the team at Glan Agua to develop a product to service the potable water site at Bruree and others around Ireland.”

The Bruree project was completed in July 2019 and was so successful that atg 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. Whilst the product was developed primarily for municipal applications, it has numerous other applications in industrial water treatment.